PLATINUM METALS REVIEW · down to magnesium (atomic number 12). ... fusible eutectic of platinum and rhodium- platinum silicide. This accounted for the fusing of the rhodium-platinum

PLATINUM METALS REVIEW

A quurterly survey of reseurch o n the platinum metuls urrd of dwelopments in their applications in industry

V O L . 8 O C T O B E R 1 9 6 4 NO. 4

Contents

Platinum in the Glass Industry

Novel Isotope Technique in Nitric Acid Plants

High Temperature Strain Gauges for Turbo- Jet Components

Corrosion Resistance of Iridium and Ruthenium

Third International Congress on Catalysis

Effect of Rhodium on the Gold-Platinum System

The Vapour Pressures of the Platinum Metals

Co-precipitation of Alloy Powders

Activated Platinum Surfaces

The Platinum Metal Phthalocyanines

Calibrating Platinum Thermocouples

Platinum Films as Temperature Probes

Abstracts

New Patents

Index to Volume 8

Communications should be addressed to The Editor, Platinum Met& Review

Johnson, Mutthey & Co., Limited, Hatton Garden, London, E.C.1

Platinum in the Glass Industry INVESTIGATING CONTAMINATION WITH THE ELECTRON PROBE SCANNING MICROANALYSER

By R. C. Jewell, A.R.s.M., B.s~. Research Laboratories, Pilkington Brothers Limited, Lathom

The modern glass indusiry is a major user of the platinurn mezals. When corrrctly used, plutinum and its alloys are practically unaffected by continuous conlact gith molten glass but if reducing conditions are a l l o l d to arise it is possible for rewtions to occur which may lead to contnmination. This article dscribes how such failures have been investigated in the Research 3,aboratories of Pilkington Brothers Limited und draws attention to the importance of avoiding reducing con-

ditions in operution.

The platinum metals are used in large quantities by the glass industry, particularly in refining and processing optical glass for lenses and prisms. Optical glass to be used for instruments has to be of the highest quality in terms of freedom from colour and from ream or local regions of inhomogeneity. Many optical glasses are highly corrosive to refractories but platinum is practically unaffected and it is for this reason that it is used for the continuous melting and stirring of optical glass of the highest quality. Rhodium- platinum alloys are also used for special parts in the production of flat glass and for bushings in the manufacture of glass fibre.

In all these applications contamination of the platinum metals can occur in service, particularly if reducing conditions arise. This contamination drastically affects not only the life of the platinum unit but also leads to colouration of the glass, which is a serious

Platinum Metals Rev., 1964,8, (4), 122-127

defect in the case of optical glass. In the examination of such contaminated platinum units the identification of the contaminant is vital to tracing its source and so to the elimination of the cause of failure. For this purpose electron probe microanalysis has been found to be invaluable. It is a relatively new analytical method initiated in France in 1951 by Castaing (I) who built the first practical instrument. The instrument has been developed further in this country by Dr Cosslett, Duncomb, Melford and Mulvey. Several descriptions of the instrument, now known as the electron probe X-ray scanning microanalyser, have been given in the technical literature (2), and only a brief description of the principles of the instrument need be given here.

A beam of electrons emitted from a heated tungsten filament in vacuum is accelerated under high voltage and focused by electro- magnetic lenses into a spot less than one micron in diameter on the surface of a metallographically prepared specimen. When electrons strike the specimen, X-rays are excited, characteristic of each chemical element in the area being examincd, which may be as small as one micron, and the emitted X-rays are analysed in a vacuum spectrometer. Quantitative analysis is made by rotating the crystal of the spectrometer to

the Bragg angle appropriate to the characteristic radiation of the particular element, and the concentration is determined either from the peak plotted by a pen recorder or by reading the number of counts in a given time from a dekatron scaler. The peak or reading is

122

Fig. 1 Cracks in a n electrically heated bushing in 10 per cent rhodium- plat inum alloy. Metallographic examination revealed intercrystalline attack with signs of f u s i o n of a contaminating phase (Fig . 2). The results of examination by the electron probe microanalyser are shown in Fig. 3

compared with that produced from a sample of the pure element or a standard of known concentration, and then converted to weight

per cent of the element detected, which can range from uranium (atomic number 92) down to magnesium (atomic number 12).

The electron probe can be made static so that a particular point or particle in the specimen can be analysed, or it can be made to scan the whole specimen. With the scanning technique an X-ray image is seen on one cathode ray tube which shows the distribution of a given element. This can be correlated with the electron image displayed on a second cathode ray tube alongside, the electron image closely resembling the optical image. Thus the distribution of an element can be correlated with the phases seen in the field of

Fig. 2 Microstructure of the contaminated rhodium- plat inum bushing showing intercrystalline attack and signs of fusion. ( x 100)

Platinum Metals Rev., 1964, 8, (4) 123

a microscope, and this is the feature so valu- able to the metallurgist.

An example of this correlation is givenin the following case. Molten glass from a furnace flowed into an electrically heated bushing of 10 per cent rhodium-platinum alloy maintained at IZSO~C, and issued as a ribbon of glass from a rectangular slot at the base of the bushing. After a time a leak developed in the side of the bushing. The glass flow was stopped and the bushing removed for examination. Two cracks were seen as shown in Fig. I. The alloy was brittle near the crack and a metallographic examination of a transverse section revealed intercrystalline attack with signs of fusion of the contaminating phase, as shown in Fig. 2.

The etched microstructure, at high magnification, of the intercrystalline contaminating phase is shown at the top of Fig. 3. There appear to be two constitutent phases, one etching dark at points 2 and 4, and the other etching light at points I and 3. The photograph immediately below shows the electron image of the same area in the X-ray microanalyser. The similarity to the optical image is readily seen. The X-ray images show the distribution of arsenic, platinum and rhodium in the respective photographs towards the bottom of Fig. 3. No contaminant other than arsenic was detected, so what were the two phases seen in the optical and electron image 3 Quantitative analysis of the dark phase at points z and 4 gave thc result:

Arsenic . . .. . . . . 20 per cent Rhodium . . .. . . 20 per cent Platinum . . . . . . . . 50 per cent

and of the light phase at points I and 3 as: Arsenic . . . . .. . . 20 per cent Rhodium . . .. . . 45 per cent Platinum . . . . . . . . 35 per cent

Thus both regions were alloys of arsenic- rhodium-platinum, but the light etching region was considerably richer in rhodium than the darker, more readily etched alloy. Arsenic both embrittles and lowers the melting point of rhodium-platinum and this

Optical x 530

Electron

Pt Lx

As K a

Rh Lx

Fig. 3 Examination by X-ray microanalysis of the contaminant phase in the rhodium-platinum alloy hushing. Arsenic, redured from arsenic oxidc present in the glass, was shown to be the cause of

contamination

was the cause of the leak. When arsenic is present in a glass it is normally there in its oxide form. In this instance the arsenic oxide was reduced locally by molybdenum used as electrodes for the electrical melting of the glass and the free arsenic so formed alloyed with the platinum of the bushing.

Another case was interesting in that the contaminating constituent is rarely encountered in flat glass manufacture although it


Fig. 4 Failure of an elec- tricalZy heated 10 per cent rhodium-plated alloy bushing by puncture and cracking at heavily contaminated areas. Again, investigation by means of the electron probe microanalyser revealed the source of contamination - in this case silicon

occurs more often in bottle glass production. This involved an experimental melt of glass flowing into an electrically heated cone shaped bushing with a cylindrical spout made of 10 per cent rhodium-platinum alloy maintained at IZOO~C. Leaks developed resulting in molten glass dribbling down the side of the platinum alloy cone, and the bushing was removed for examination. Two leaks at the base of the cone were found and the tubular spout had cracked as shown in Fig. 4. Fused metal from the punctured areas had flowed down the outside of the tube, leaving a wake of alloy with a rippled surface terminating in a fused blob. Metallographic examination of

a transverse section showed heavy contamination of the rhodium-platinum by a grey dendritic phase as seen in Fig. 5. The specimen was put in the microanalyser and one arm of the dendrite was examined. The electron image at high magnification is shown in Fig. 6a. X-ray microanalysis revealed silicon as the contaminant, the X-ray image showing the distribution of silicon in the dendrite is given in Fig. 6b; The correlation with the electron image is readily seen.

It also appeared that the centre of the dendrite had a lower silicon content than the outside layers. Fig. 6c shows the relative concentration of silicon along the path of the scan, shown as a white line in Fig. 6a, through the section of the dendrite. There is little silicon in the matrix of uncontaminated rhodium-platinum alloy, but as soon as the dendrite is reached the silicon content rises sharply, falling a little in the middle then rising again for the outside edge and finally

Fig. 5 Microstructure of a rhodium-platinum bushing h e a d y contaminated by silicon. The grey areas are silicide of rhodium-platinum, the white areas unrontaminated rhodium-platinum. ( X 150)


Fig. 6a (top) Electron image o j dendrite showing line of scan ( x 800); 6b (middle) X-ray image of Si K x showing distribution of silicon (~800); 6c (bottom) Si Kx distribution of silicon along line

of scan of Fig. 6a ( X 800)

A third example illustrates the great value of the X-ray microanalyser to the metallurgist. The special need to ensure complete homogeneity in optical glass requires that the molten glass must be adequately stirred prior to casting. This stirring may take place at temperatures from 1000 to 1300T or even higher, depending on the viscosity of the glass which in turn is dependent on its composition. For this purpose a material with high hot strength at these high temperatures is necessary and at the same time it must be resistant to corrosion by molten glass. Molyb- denum is very suitable for hot strength and has a high melting point, but it can colour glass owing to slow solution under strongly oxidising conditions, and moreover it forms an oxide which volatilises rapidly in air at about 7ooOC.

The colouration of glass and the oxidation can be overcome by coating the molybdenum stirrer with platinum or with rhodium- platinum alloys. However, difficulties arise at high temperatures owing to diffusion of molybdenum into the platinum to form a brittle zone which eventually causes fracture

dying away in the matrix of the uncontaminated rhodium-platinum. Silicon readily alloys with rhodium-platinum to form a fusible eutectic of platinum and rhodium- platinum silicide. This accounted for the fusing of the rhodium-platinum alloy at the locally heavily contaminated areas, the fused alloy then running down the tube. The associated cracking is due to the brittleness of platinum silicide.

Fig. 7 Platinum contaminated 6.y arsenic as shown by the pale grey areas. The black areas are glass

inclusions ( x 200)


of the platinum cladding under stress. In one example of a platinum clad molybdenum stirrer, the cladding had burst and glass had run in. Metallographic examination of a transverse section cut from the platinum cladding showed a pale grey phase occurring as discrete particles and at the grain boundary, as shown in Fig. 7. Particles of glass were intimately mixed and embedded in the embrittled platinum so that it would have been impossible to eliminate all traces of glass from a sample for analysis by optical spectrograph. Since the glass contained arsenic oxide, arsenic would have been reported by this method of analysis. Arsenic certainly would embrittle platinum but a particle of glass containing arsenic (as oxide) by itself would not. The X-ray microanalyser was brought into action on the polished and etched section and by pin-point analysis the round metallic phase and grain boundary contaminant were identified in situ as arsenic. There was now no doubt that the arsenic revealed by this analysis was the contaminating phase in the platinum, and not the arsenic oxide present in the closely adjacent glass particles. Here again the local reduction of

the oxide of arsenic present in the glass to arsenic by the molybdenum of the stirrer led to contamination of the platinum cladding after it had burst and allowed molten glass to come into contact with the molybdenum.

There are many other applications to which the electron probe microanalyser has been put. Diffusion studies of metal into glass, as well as metal into metal; identification of metallic inclusions in glass; variation in homogeneity in glass, and the variation in composition of extremely thin weathering bands in ancient glass, have been revealed. The technique of X-ray microanalysis in the fields of mineralogy and biology are being developed, but its outstanding usefulness in being able to analyse minute areas of the microstructure of metals as seen under the microscope is of immense value to the metallurgist.

References R. Castaing, Thesis Paris University, ONERA

Publication No. 51, 1951 X-ray Microscopy and X-ray microanalysis:

Proceedings of Second International Sym- posium, Stockholm, 1960. Edited by A. Engstrsm, V. E. Coslett, and H. H. Pattee, Elsevier Publishing Co, 1960

I

2

Novel Isotope Technique in Nitric Acid Plants TRACING METAL LOSSES FROM PLATINUM ALLOY GAUZES

A significant factor in the economics of nitric acid production is the loss of rhodium- platinum from the gauzes employed in the ammonia oxidation converters. These losses are particularly important in high-pressure plants, where they may be more than ten times as high as in low or atmospheric pressure plants.

Karel Akerman and co-workers at the Institute of Nuclear Research, Warsaw, have described a series of experiments carried out in a nitric acid plant at Tarnow, Poland, aimed at tracing the whereabouts of the platinum alloy lost in operation (Przemysl Chemiczny, 1964, 43/6, 306). A platinum gauze containing z per cent iridium was neutron activated in a reactor untilit contained an activity of approximately 280 mC resulting

from the formation of IrIg2. This isotope has a half-life of 74.4 days and proved much more suitable for the experiments than the shorter lived isotopes Irlg4 and Ptl$’ that are also formed. The latter were eliminated from the irradiated gauze by storing it for two weeks before use.

The activated gauze was placed with other rhodium-platinum gauzes in the converter, and the plant operated for thirty-eight days. Activated platinum alloy that had been lost from the gauze was traced throughout the plant with a scintillation counter and the various dust deposits located. It was found that the rate of loss was highest shortly after start-up of the plant and that a good estimate of the dust filter efficiency could be obtained.

H.C.


High Temperature Strain Gauges for Turbo- Jet Components ADVANTAGES OF PLATIlyulM ALLOY RESISTANCE WIRES

By R. Bertodo Bristol Siddeley Engines Ltd, Edgware

Since 1953 an extensive research programme has been in hand at the Electro- Dynamics Laboratories of Bristol Siddeley Engines Limited on the basic properties of resistance strain gauges (I, 2) in order to develop elements capable of producing altcr- nating strain data within an accuracy of & 5 per cent at temperatures up to IOOO"C and steady strain data within a similar accuracy but in the temperature range -70 to -t65ooC, mainly from turbo-jet components operating in oxidising atmospheres. A total of fifty-four alloy systems have been examined so far and, more recently, greater emphasis has been given to alloys of the platinum metals (3). This change of emphasis has resulted from the greater amount of effort being devoted to the development of elements suitable for the measurement of steady strains.

When using resistance strain gauges to derect alternating stresses, temperatwe- and time-induced resistance changes may gencr- ally be reduced to secondary effects by suitable instrumentation. This is not possible when steady strain data are required, since these variations would provide either a shift or complete loss of the original reference zero, so invalidating the results. The maximum value of electrical resistance drift that can be tolerated will depcnd upon the degree of accuracy required and the general stress level normally encountered. For a steady stress level of 10 tons/sq. in. and a required accuracy of 5 per cent, the maximum acceptable drift from all causes cannot exceed IOO to 150

p ohm/ohm or must be compensated to better than this value. A high degree of resistance to corrosion and oxidation is therefore essen- tial if the gauge is required to remain stable at high temperatures for long periods of time, since a diametral change of only 0.001 per cent in the strain wire may result in a resistance change in excess of 200 p ohm/ohm. Some alloys will suffer preferential oxidation under these conditions, resulting in a permanent resistivity change due to depletion of one or more of their constituents. Where the resistivity changes owing to depletion are negative, they may compensate the positive resistance changes due to oxidation and corrosion when

D d c D 9 = _, 10-2

where dp/dc is the rate of change of resistivity with composition, p the alloy's resistivity, D its density and D' the density of the preferen- tially oxidised constituent. Theoretical cvn- siderations suggest that such compensation can be more readily achieved with alloys having an oxidation rate of 0.002 g/m2h or less.

Tests carried out on twenty-one binary and ternary noble metal alloys have clearly indicated that some platinum metal alloys are sufficiently stable : the number of alloys having a suitable dp/dc is much more limited and, consequently, very few wires are suitable for the measurement of steady strains at high temperatures. The best characteristics so far have been obtained with binary alloys of the face centred cubic platinum metals with one another or with metals of Group VIA. The

Platinum Metals Rev., 1964, 8, (4), 128-130 128

work has been hampered by the sluggishness of structural changes in many of these alloys and the large property changes associated with such modifications. For example, the strain sensitivity - that is the electrical resistance change per unit applied strain - of iridium-platinum alloys increases from 4.9 for pure annealed platinum, to 6.5 as the solid solution to duplex alloy transitional composition is approached, falling again, as greater quantities of iridium are added, to 4.2 at the 25 per cent by weight iridium alloy. Exposure of rhodium-platinum alloys to irradiation of the order of 5 x 1oZo nvt will modify the strain sensitivity and resistance characteristics by significant amounts, the changes being attributable to neutron capture and the consequent transmutation of rhodium to palladium. Some alloys of the chromium-palladium and tungsten-platinum systems exhibit outstanding long-term stability at high temperature

under oxidising conditions. In order that the temperature coefficient of resistance may be acceptably low, suitable alloys must contain at least 20 per cent by weight of chromium or, as shown in the graph on page 130, a t least 8 per cent by weight of tungsten. The strain sensitivity of high chromium-palladium alloys is modified by moderate straining and greater effort has therefore been devoted to the tungsten-platinum series of alloys containing between 8 and 10 per cent by weight tungsten.

Typically, an annealed alloy containing 9.5 per cent tungsten will have a room temperature tensile strength of 142,000 lb/ sq. in. falling to 83,000 lbjsq. in. at 6oo3C, an oxidation rate in still air at 600°C of 0.00085 g/m2h, a resistivity at zo"C of 74.2 11 ohm-cm, a temperature coefficient of resistance (o-IOOO'C) of 145 p ohm/ohm/"C and a coefficient of thermal expansion (O-IOOO'C) of 8.9 p in./in./"C.


> t L k m z W m

TUNGSTEN - WEIGHT PER CENT

Electrical and mechanical properties of tungsten- platinum alloys. All specimens were in the annealed condition except that represented by the broken line, which was in the hard drawn state.

Strain elements wound from 0.001 inch diamcter wire, annealed and stabilised by soaking at 600°C for IOO hours will have a strain sensitivity of 3.74 h0.008 (95 per cent confidence limits) with a standard deviation of 0.126. The sensitivity will fall at the rate of 0.042 per cent per "C with increasing temperatures. Exposure to oxidising atmos-

pheres at 63oCC for periods of up to zoo hour/ indicates a drift rate equivalent to 14 p ohms ohm/h; no significant changes in strain sensitivity or temperature coefficient of resistance will result. Successful tests have been carried out using elements of this type bonded to engine rotating parts operating at temperatures up to 6oo0C, as shown in the photograph. After a five-hour test, the elements were rccalibrated: there appeared to be no change in temperature coefficient of resistance, drift rate or strain sensitivity. The permanent resistance change was 70 p. ohm/ ohm (equivalent to 700 lb/sq. in. in steel).

It is evident that platinum metal alloys offer significant improvements in strain sensitivity, stability and resistance to adverse environmental conditions and there is little doubt that wider acceptance of such alloys will result in greatly improved techniques.

References I R. Bertodo, Development of High Tempera-

ture Strain Gauges, Proc. Inst. Mech. Eng.,

z R. Bertodo, Resistance Strain Gauges for the Measurement of Steady Strains at High Temperatures, Proc. Znst. Mech. Eng., 1964, Preprint P34/64

R. Bertodo, Kesistance Strain Gauge Research. Part 7: Precious Metal Alloy Wires. Bristol Siddeley Engines, Electro-Dynamics Report No. EDR 378, 1962 (Classified)

'9593 I73J 605

3

Corrosion Resistance of Iridium and Ruthenium ATTACK BY LIQUID METALS

Recent progress in methods of fabricating iridium and ruthenium has focused attention on their special properties of high melting points and resistance to chemical attack. D. W. Rhys and E. G. Price have now reported (Metal Ind., 1964 (August zoth), 243-245) the results of tests designed to show the amount of attack by nineteen liquid metals on sintered specimens of iridium and ruthenium contained in crucibles of the same material. Under the test conditions neither iridium nor ruthenium were attacked by lithium, sodium, potassium, silver, gold,

Platirium Metals Rev., 1964, 8, (4)

mercury, indium, or lead. Copper, cadmium, tellurium and tin did not attack ruthenium, and bismuth did not attack iridium. Calcium, gallium, and bismuth only slightly attacked ruthenium, and gallium also only slightly attacked iridium.

Some alloying and/or solution occurred with ruthenium for magnesium, zinc, aluminium, and antimony. Iridium was affected by these metals and also by copper, calcium, cadmium, tin and tellurium.

The most severe attack occured with zinc by rapid solution.

130

Third International Congress on Catalysis THE ROLE OF THE PLATINUM METALS IN HETEROGENEOUS CATALYTIC REACTIONS

The Third International Congress on Catalysis, organised most eficiently by the Royal Dutch Chemical Society, took place in Amsterdam from July 20 to 25. It was attended by 828 active members from 31 countries including 141 from the USA, 29 from the USSR, and 115 from Great Britain. Of the ninety-eight papers presented, twenty-seven refer to the use of the platinum group metals as catalysts, and these are reviewed here.

In order to restrict the scope of the meeting, two themes had been selected by the organi- sing committee: these were (i) Selectivity in Catalytic Reactions, and (ii) the Molecular Description of Catalytic Reactions. In addition to a full programme of discussion of the papers, there were six general lectures that covered some of those aspects of catalysis not included in the main themes. Two of these lectures of particular interest to those working with the platinum metals were those by Professor R. S. Nyholm on the structure and reactivity of transition metal complexes and by Professor J. Halpern on developments in homogeneous catalysis.

The proceedings of the Congress will be published by the North Holland Publishing Company, Amsterdam.

For the purpose of this short review, the papers of greatest interest have been classified under the headings : (i) Catalytic Reforming, (ii) Aromatic Ring Reduction, (iii) Reduction of Other Unsaturated Groups, and (iv) Miscellaneous Processes.

Catalytic Reforming Six papers were concerned with catalysts

for the reforming of hydrocarbons and the related mechanisms of reactions. J. A. Rabo, V. Schomaker and I?. E. Pickert, of Union Carbide, described a technique for ion-

Platinum Metals Rev., 1964, 8, (4), 131-133

exchanging a calcium Y zeolite with [Pt (NHJ4IZ1 to give after reduction a Pt content of 4 per cent. This catalyst was resistant to poisoning by thiophen. The same zeolite on impregnation with H,PtCI, to give after reduction the same Pt content was rapidly poisoned by thiophen. They concluded that the Pt in the former catalyst was atomically dispersed.

Another novel procedure was described by A. G. Goble and P. A. Lawrance of the British Petroleum Company Ltd. These authors showed that treatment of a Pt/A1,0, catalyst with carbon tetrachloride vapour at 300°C resulted in the chlorination of surface hydroxyl groups, and that the resulting catalyst could isomerise n-hexane even at room temperature with remarkably high selectivity.

H. J. Maat and L. Moscou (Ketjen N.V.) showed that increasing the platinum crystallite size by sintering led to a decrease in dehydrocyclisation activity, accompanied by an increase in isomerisation activity. V. Haensel, G. R. Donaldson and F. J. Riedl of Universal Oil Products, reported that methylcyclo- pentene was a primary intermediate product in the conversion of methylcyclopentane to benzene over Pt/A1,0,, and that cyclohexene could be detected in the dehydrogenation of cyclohexane to benzene at high space veloci- ties. Its yield was greatly increased on

131

partially poisoning the catalyst with tert- butyl mercaptan. Kh. M. Minachev and G. V. Isagulyants (U.S.S.R.) were however unable to detect cyclohexene in the dehydrogenation of cyclohexane over Pd/Al,O, at 480°C. S. Khoobiar, R. E. Peck and B. J. Reitzer, of the Illinois Institute of Tech- nology, studied the kinetics of cyclohexane dehydrogenation over Pt/A1,0, in an iso- thermal reactor, and they suggested that although reaction was initiated on the catalyst pellets it was probably propagated on the surface of the added ‘inert’ alumina.

Aromatic Ring Reduction Five papers were devoted to the problem

of the mechanisms of the hydrogenation and exchange of benzene and its methyl deriva- tions over the platinum group metals and emphasis here also was on the role of olefinic intermediates.

S. Siege1 and V. Ku (University of Arkansas) have detected them during the liquid-phase hydrogenation of the xylene isomers : concentrations varied between 0.02 and 0.7 mole per cent. They conclude that virtually every saturated molecule formed passes through the desorbed olefin stage, F. Hartog, J. H. Tebben and C. A. M. Weterings, of Dutch State Mines, studied the hydrogenation of benzene over platinum, palladium and ruthenium catalysts, using both hydrogen and deuterium, with full product analysis in the latter case. They concluded that C,X, and C,X, species (X=H or D) were common intermediates for both hydrogenation and exchange, and that cyclohexene was an intermediate, but even in the most favourable case, which is ruthenium, only about I per cent desorbs from the surface. The paper presented by R. J. Harper and C. Kemball (The Queen’s University, Belfast) dealt with the exchange and hydrogenation of p-xylene over films of platinum, palladium and tungsten. Exchange of the methyl groups was the most rapid process, followed by the slower ring exchange and hydrogenation processes. No olefinic intermediates were

detected in this work. H. A. Smith and W. E. Campbell, of the University of Tennessee, measured the rates of reduction of benzene and a series of rnethylbenzenes alone and in competition over Rh/A1,0,, and from their results were able to calculate the relative strengths of adsorption of the molecules.

K. Hirota and T. Ueda (Osaka University) observed that in the exchange of p-xylene with D,O, platinum and palladium catalyse the exchange of both ring and methyl hydrogens; iridium, ruthenium and rhodium do so less efficiently, while nickel and cobalt can only exchange the methyl hydrogens.

Reduction of Other Unsaturated Groups

Comparatively few papers were devoted to the hoary old problem of the mechanism of the hydrogenation of olefins catalysed by the platinum group metals. J. Turkevich, F. Nozaki and D. Stamires (Princeton Univer- sity), in what was widely agreed to be one of the most impressive papers of the Congress, examined the electron spin resonance of Pd/Al,O,, and on this basis proposed a donor- acceptor model for catalytic hydrogenation. J. L. Carter, I?. J. Lucchesi, J. H. Sinfelt and D. J. C. Yates (Esso Research and Engin- eering Co) studied the hydrogenation of ethylene over Pt/A1,0, and concluded that migration of active intermediates occurred between the Pt and Al,O, centres. G. V. Smith and J. A. Roth (Illinois Institute of Technology) investigated the addition of deuterium to dimethylitaconate and its isomers, and obtained evidence for an intra- molecular hydrogen transfer. G. C. Bond and J. S . Rank (Johnson Matthey and Co Ltd) showed that the rate of double-bond migration in I-pentene relative to its rate of hydrogenation was similar for palladium on a number of supports, and for Pd/C in a number of solvents. They also studied the liquid-phase hydrogenation of the pentynes and penta- dienes using platinum, palladium, ruthenium, rhodium and iridium catalysts, and obtained product distributions. J. J. Phillipson, P. €3.


Wells and D. W. Gray, of the University of Hull, studied the gas-phase hydrogenation of 2-butyne using platinum, rhodium and iridium supported on alumina, and discussed reaction mechanisms in detail.

Miscellaneous Processes Two interesting papers concerned the

mechanism of the hydrogen-oxygen reaction. V. Ponec, Z. Knor and S. tern? (Czechoslovak Academy of Science) followed the chemisorption of hydrogen and of oxygen, and their interaction, on films of rhodium, palladium, nickel and molybdenum by electrical conductivity changes. s. Z . Roginsky (Institute for Chemical Physics, Moscow) summarised a great deal of published work, chiefly con- cerning the isotope effect in this reaction.

J. R. Anderson and N. J. Clark, of the University of Melbourne, studied the reactions of hydrogen cyanide on evaporated films of platinum, palladium and a number of other metals. Kobozev, Krilova and Shashkov, of the Moscow State University, investigated

the exo-electron emission of platinum on several supports : this novel and simple technique merits further application.

Conclusions The limitations imposed by the organisers

of the Congress on its scope resulted in an overall impression of a strong ‘academic’ flavour: only the general lecture by Professor Boreskov on the theoretical bases of selection, preparation and use of industrial catalysts served partially to restore the balance. In the papers reviewed here, there were two re- current themes, first, the detection and description of reaction intermediates, using a variety of techniques and approaches, and secondly the role of the support, with particular reference to the possible activation of the support by the metal, for which concept there is now much indirect evidence. It remains to be seen to what extent these issues are clarified before the next Congress, which it is hoped will be held in the Soviet Union in 1968. G . C. B.

Effect of Rhodium on the Gold-Platinum System Those gold-platinum alloys used for the

manufacture of spinning jets in the production of viscose rayon have for many years been modified by small additions of rhodium, which appeared to broaden the miscibility gap and assist age-hardening. A recent X-ray study by Raub and Falkenburg ( I ) has shown that approximately 2 atomic per cent of rhodium completely eliminates the gold rich solid solution which normally contains 20 per cent or more of platinum. Although rhodium also reduces the solubility of gold in platinum, the effect is not so pronounced, and platinum rich solid solutions extend right across to the rhodium corner of the diagram.

Although Raub had earlier predicted the basic instability of the rhodium-platinum solid solutions it was found that heat treatments extending up to four years at 600°C failed to produce any evidence of separation. The binary gold-rhodium system was also examined. At the peritectic temperature of 1068°C saturation concentrations of the

Platinum Metals Rev., 1964, 8, (4)

terminal solid solutions were found to be 1.5 atomic per cent of rhodium and 0.3 atomic per cent of gold.

In 1951, Grube, Schneider and Esch (2) attributed some additional lines on the diffraction pattern of a gold rich gold-platinum solid solution to an ordering reaction based on the Au-Pt composition. No other workers have hitherto detected these lines. Raub and Falkenburg, however, developed similar “sideband” structures simply by annealing the alloys for 1,000 hours in the solid solution region. Thelattice parameter of this additional face-centred cubic phase increased rapidly with platinum content. This behaviour cannot easily be explained by an ordering reaction and will require further investigation.

A. S. D.

References I E. Raub and Giinter Falkenburg, Z.

2 G. Grube, A. Schneider and M. Esch, Metallkunde, 1964, 55, (71, 392-397

Heraeus Festschrift, i951,20

133

The Vapour Pressures of the Platinum Metals A REVIEW OF SOME RECENT DETERMINATIONS

By A. s. Darling, Ph.D., A.M.1.Mech.E. Research Laboratories, Johnson Matthey & Co Limited

The platinum metals occupy a strategic position in the transition element series and current interest in the bonding processes of this complex group of metals places particular emphasis on accurate vapour pressure determinations. Some of the platinum metals, are, of course, being used increasingly in vacuum deposition processes and the subject is not therefore without its practical implications. This article presents a critical survey of the most recent determinations of vapour pressures and heats of vaporisation.

The surface of a heated metal exposed to vacuum constitutes a phase boundary of remarkable interest. By simple application of the kinetic theory of gases the flux of atoms leaving the surface can be correlated with the equilibrium vapour pressure of the metal, and the slope of the temperature/vapour pressure curve provides a direct measure of the difference in energy level between the crystalline and gaseous states. The oppor- tunity to identify the molecular species of the vapour phase and to determine at the same time, in a quantitative fashion, how the atoms or molecules acquire sufficient energy to leave the crystalline lattice, derives from the unique and elegant simplicity of the experimental arrangements, and vapour pressure studies have had an irresistible fas- cination for many students of the metallic state. Undue enthusiasm has sometimes led to a rather uncritical acceptance of the heat of sublimation as a reliable index of the strength of the crystalline bond, although the errors implicit in this view are now more fully appreciated.

Platinum has been used at high temperatures ir, electrical technology for many years and

early determinations of its vapour pressure were undertaken for practical rather than for theoretical considerations. High temperature applications for the other mcmbers of the platinum group are, however, rather more limited, and recent cvaporation studies on these metals have undoubtedly been stimu- lated and encouraged by the current interest in the bonding processes of the transition metals. The results obtained show very plainly that the identity of the platinum metals “as an isolated group, inseparable and solidly constituted” (I) is supported by both the physical and chemical evidence.

Platinum Observations of the rate of evaporation

from heated platinum filaments were first made by Edison in 1879 (2) and it is significant that the incandescent lamp tradition at the General Electric Research Laboratories should have led directly, at a later date, to Langmuir’s classical vapour pressure studies. Langmuir’s data (3), corrected in 1927 (4) to conform with the International Tempera- ture Scale, agree remarkably well with recent determinations reported by workers at

Platinum Metals Rev., 1964, 8, (4.1, 134-140 134

Fig. 1 Experimental vapour pressure data on platinum and palladium

their specimens indirectly i8 - by radiation from a graphite susceptor. By using a -9

/ /

/ +

Walker avoided any possibility of carbon contamination, and this precaution probably accounted for their higher vapour pressure measurements.

In the Langmuir technique vapour pressures (P) are calculated from the rate of evaporation (m) in accordance with the expression :

where a is the accommodation coefficient, M is the molecular species and T the absolute temperature. The method has often been criticised because the accommodation coefficient is not necessarily unity. In most experiments, however, this uncertainty is a minor source of error. From the experimental results plotted in Fig. I it will be seen that a 7% temperature variation will completely mask any error caused by a 25 per cent change in accommodation coefficient. Temperatures must usually be optically determined, and as surface evaporation leads to a continuous change of emissivity, it will be appreciated that the main errors in Langmuir experiments originate in faulty temperature measurement.


Liquid metals sometimes have very low accommodation coefficients and this subject has been reviewed by several authors (7, 8). Most of the experimental evidence suggests, however, that erroneously low evaporation rates are unlikely to be consistently obtained from determinations on solid specimens. Systematic errors can usually be revealed by extrapolating the apparent vapour pressure curve backwards. If this yields a plausible heat of evaporation, the accommodation coefficient is unlikely to be much less than unity. Further confirmation can be obtained by drilling holes in the specimen to increase its total surface area. Reentrants of this type will only result in an increased evaporation rate if x is significantly less than unity.

Errors caused by an intermittent change in accommodation coefficient can often be avoided by varying the temperature in a random manner. Hampson and Walker’s work (5) provides a good illustration of this technique. Variations of surface conditions sometimes led to anomalously low evaporation rates that were so obviously inconsistent with

135

the United States Bureau of Standards (5). These exper- imenters, together with Dreger and Margrave (6), employed the Langmuir free evaporation technique and the results should therefore be directly com- p a r a b l e . D r e g e r a n d Margrave, however, heated

water cooIed flux concen- t r a t o r H a m p s o n a n d TEMPERATURE

-2 10

G3

(5 a - 4 p 10 2 2 Y -! g 10 a

B ' lo'

3

4

-

RHODIUM + KNUDSEN 12.13 0 LANGMUIR 16 - LANGMUIR 5

0 LANGMUIR 12, 13

~

10 1600 1800 2000 2200 2400 2600

TEMPERATURE K

the bulk of the data that they could be safely ignored. The conditions causing these stages of low evaporation were not fully understood, except that they tended to occur after fairly lengthy periods at high temperature. "Normal" sublimation rates were readily restored by a sudden rise in temperature. It appears reasonable to attribute the low vapour pressure determinations of Dreger and Margrave to a 50 per cent decreasc in accommodation coefficient caused by carbon contamination.

In view of the excellent agreement between Hampson and Walker's data and those of Jones, Langmuir and Mackay, the NBS vapour pressure equation :

27,575 Log P,,--9.642- __ T appears to be applicable from 1650°K to the melting point of platinum. All three sets of results yield concordant heats of sublimation, varying from H,(298) -134.6 kcal' mole for Jones et al. to 135.2 kcal/mole for Dreger and Margrave. After making allow- ances for experimental scatter, errors in temperature measurements and weight loss measurements, Hampson and Walker conclude that H,(298) -134.9 - 1.0 kcaI/mole, a value which embraces the other two sets of

Fig. 2 Experimental uapour pressure datu an rhodium and iridium

determinations and corresponds to a +- 25 per cent limit of error in vapour pressure measurement.

Palladium The general belief that palladium

had the highest vapour pressure of the platinum metal group was, until )O

comparatively recently, supported by very little reliable evidence. The

first serious determinations were those of Haefling and Daane (9) who used the Knudsen technique and lined their graphite effusion vessel with tungsten. Measurements were made at temperatures just below the melting point of palladium. Their results, shown in Fig. I, were approximately one order of magnitude higher than those of Dreger and Margrave (6) who used the Langmuir method and measured the rate of loss of weight of a palladium rod heated by radiation from a graphite susceptor.

Haefling and Daane's (9) heat of sublimation, calculated from the shape of the vapour pressure curve, was 80 kcal/mole at 298"K, and considerably below the mean value of 91.0 obtained by Drcger and Margrave. The pronounced temperature dependence of both sets of results indicates some type of systematic error. The graphite effusion vessel of Haefling and Daane was not degassed above 1500°C and might well have lost weight during the experiment, thus causing erroneouslq high vapour pressure determinations. The presence of carbon vapour could easily have influenced Dreger and Margrave's determination in the opposite sense, by reducing the accommodation coefficient.


Hampson and Walker (10) at the Bureau of Standards used a water cooled copper flux concentrator for heating their palladium specimens and avoided any possible uncertainty. Their results, shown in Fig. I, are intermediate between those of the previous investigators. A comparison of the platinum and palladium results shows that in both instances the vapour pressure determinations of Hampson and Walker are approximately 50 per cent higher than those of Dreger and Margrave. Since both groups of workers paid particular attention to the precision of their temperature measurements, the discrepancy is reasonably attributable to the presence of some unsuspected surface contamination emanating perhaps from the graphite susceptor.

The NBS determinations are very consistent and their vapour pressure equation (10)

18,655 Log P,,=8.749 - - T

appears to be applicable from 1200" to 1700°K. The mean heat of sublimation was estimated to be 89.2 kcal/mole at 298°K with an overall limit of error of 5 0.8 kcal/mole, corresponding to a possible uncertainty of f 33 per cent in the vapour pressure measurements.

Iridium Vapour pressure determinations on iridium

by both the Knudsen and Langmuir techniques have been recently reported by Panish and Reif (11, 12, 13) whose results link up remarkably well with the lower temperature values obtained at the NBS (5). The first published information ( I I) was obtained with

effusion cells having an orifice too large to ensure internal saturation. This led to improved Langmuir and Knudsen experiments which provided mutually confirmative results.

The high consistency of the experimental data plotted in Fig. 2 suggests that iridium under high vacuum conditions has an accommodation coefficient of unity and that no serious errors are involved in using the free evaporation method. Hampson and Walker (5) did, however, report one or two test runs in which the indium refused to evaporate. It seems reasonable to attribute this effect to carbon contamination, as the NBS apparatus, although protected with a liquid nitrogen trap, was evacuated by an oil diffusion pump. Panish and Reif used ionisation pumps, and as their vacuum was less likely to be contaminated by hydrocarbon vapours, it became possible to study the effect of carbon in an unambiguous manner. The presence of graphite within the effusion cell was shown (13) to reduce the vapour pressure of iridium by one or two orders of magnitude. Carbon apparently does more than merely reduce the accommodation coefficient of heated iridium although Panish and Reif were unable to observe any signs of surface reaction.

Under suitable conditions atomically clean surfaces of refractory metals can be produced by heating in high vacuum (14). This method is particularly applicable to iridium whose surface impurities are all likely to be more volatile than itself. The high catalytic activity of iridium, however, indicates that vacuum conditions are likely to be stringent.

Investigators Vapour Pressure Equation Temperature Heat of Range Vaporisation

H,,, kcal/mole

Panish et al. (13) Log,oPmm= 10.46 - 33y980 - 2100-2600~K T

Hampson and Walker ( 5 ) Log,$,,= 10.020- 331337 ___ 1986-2260~K Isg.9&2.0

T


- I 10

-2 10

- 3 a lo a 2 z -4

10 a w

3 ln ln

-5 I 1 0 a 3

2 -6 10

RUTHENIUM (I3 +l7)

0 EFFUSION ' l3 iORlFlCE + EFFUSION '/16'0RIFICE A LANGMUIR

A LANGMUIR (17) 1 /

-7 10

Fig. 3 Experimental vapour pressure data on osmium and ruthenium

At 2030'K this curve links up with that of Panish and Reif ( IZ), which is applicable between 2050 and 2200OK.

Log P,,= 10.28 - 28;m __ (12)

Third law analysis of the 2000 2100 2 2 0 0 2300 2400 2500 2600 2700 2aoorhodium evaporation data by

TEMPERATURE ' K

Roberts (15) has reported that iridium cracks ethylene at IOOOC to produce a tarry deposit and these reactions are likely to be greatly accelerated at higher temperatures.

Panish et al. (13) used a time of flight mass spectrograph to confirm the monatomic nature of iridium vapour. Their vapour pressure equation is almost identical with that of Hampson and Walker, both of which are tabulated at the foot of page 137.

Rhodium Three independent groups of investigators

have studied the vapour pressure of rhodium with results as indicated in Fig. 2. Their continued use of a graphite susceptor probably explains why Dreger and Margrave's data (16) are less consistent and tend to be lower than those of Panish and Reif (12, 13) or Hampson and Walker (5). In view of the excellent agreement between the results obtained by free evaporation and by effusion there appears to be little doubt that rhodium, when heated in a clean vacuum, has an accommodation coefficient approaching unity. The vapour is monatomic (13). Between 1700 and 2075°K the vapour pressure is best defined by the following equation:

271276 L0g10P,rn==9.775 - T ( 5 )

Panish and Reif yielded a heat of evaporation of AH,,, 7132.8 h0.3 kcal/ mole, which agrees well with Hampson and Walker's value of 132.5 f2.o kcal/mole.

Osmium Langmuir experiments by Panish and Reif (17) on sintered cylinders heated by an electron beam showed that the vapour pressure of osmium is less than IO-~ mm of Hg at 2100'C. The vapour is monatomic, and the best line through the experimental points on Fig. 3 is represented by:

Third law calculations using standard free energy functions yielded a heat of vaporisation at 298°K of 187.4h0.9 kcal/mole. This value is considerably higher than earlier estimations (18, 19).

Ruthenium Panish and Reif have studied the evapora-

tion of ruthenium in considerable detail (13~17). Due to a reaction between ruthenium and the effusion cell liner appreciable quantities of thoria were found on the targets and this made it impossible to use w-eight changes as an index of evaporation rates. The quantity of ruthenium emanating


Fig.. 4 Rates qf evaporation in vacuo of the six platinum metals

from the cell was determined, therefore, by the use of Ru as a tracer. The vapour pressure determinations made with & inch and & inch diameter orifices, although scattered, fell along the same line as those of the Langmuir experiments. Added confirmation that the accommodation coefficient of ruthenium was unity was obtained by grooving the specimens to double their total surface area. This had no effect upon the evaporation rate. The line drawn through the experimental points on Fig. 3 is represented by the equation:

33,480 (17) Log,,P,,= 10.81 - - T

The heat of vaporisation, calculated from the vapour pressure measurements with the aid of appropriate free energy functions, was found to be AH,,, =154.9 f 1.3 kcal/mole.

At the upper level, Panish and Reif heated their specimens, without melting, to 2318°C~

, 41 4 2 43 44 45 46 47 4a 73 14 15 76 71 70 79 80

ATOMIC NUMBER

-2 10

-3 10

i 104 . N I v - 5 . 10 I u I -6 3 10

s -7 f 2 - 8

f3 V

10

z c 10 Q d 0 P - 9 p 10

8 -10 w (0

W

k d - 1 1 10

-12 10 I 1 I

1200 1400 1600 I 800 2 0 0 0 2200 2400

TEMPERATURE O C

which falls just within the uncertainty range of the most reliable recent melting point determinations (20).

1-0

0.9

0.8 .---. N

5 0.7 y"

L

0

0 w x

> t- - =!

0 5 g

a U-J U-J W

0.4 5 0 U

0.3

0.2


Rates of Evaporation The curves in Fig. 4 show the

theoretical rates of evaporation from the surface of pure platinum metals in vacua The volatility of palladium is approximately 9 orders of magnitude higher than that of osmium. In spite of their higher melting points rhodium and ruthenium evaporate more rapidly than platinum and iridium respectively, and the curves provide an effective illustration of the higher thermal stability of the heavier triad.

Fig. 5 Heats of vaporisation and com- pressability data plotted as a function of atomic number. (Compressibiliries from Bridgman, 1949 (23) . Heats of vaporisu- tion for metals other than those in the platinum group from Honig (24))

The theory of the transition metals is still a matter of considerable controversy, and vapour pressure measurements have been used to cast light on the atomic bonding processes. Robins, in 1959 (21), postulated that the metals towards the centre of the second and third long periods tended towards higher stability as the number of bonding electrons approached half the effective co- ordination number. The high heats of vaporisation of tungsten and molybdenum were used as an illustration of this conception. Compressibility values, which according to other authorities (22) provide a more reliable indication of bond strength in the crystalline state, reach minimum values at ruthenium and iridium. The heats of evaporation and compressibilities of the elements most concerned in these hypotheses are plotted in Fig. 5.

References I C. E. Claus, J . Prakt. Chem., 1860, 80, 282

2 T. A. Edison, Chem. News, 1879,40, 152-154 3 I. Langmuir and G. M. J. Mackay, Phys. Rev.,

4 H. A. Jones, I. Langmuir and G. M. J.

5 R. F. Hampson and R. F. Walker, J. Res. Nut.

6 L. H. Dreger and J. L. Margrave, J. Phys.

7 0. Knacke and I. N. Stranski, Progress in

(ChemicalNews, 1861,3,194)

1914, 41 377

Mackay, Phys. Rev., 1927, 30, 201

Bur. Stand., 1961,65A, (4) 289

Chem., 1960,64, I323

MetalPhysics, 1956,6,181

8 A. N. Nesmeyanov, Vapour Pressure of the Chemical Elements, 1963, Amsterdam, Elsevier

9 J. F. Haefling and A. H. Dame, Trans. Met.

10 R. F. Hampson and R. F. Walker, J. Res. Nut. Bur. Stand., 1962, 66A, (2), 177

X I A. A. Hasapis, M. B. Panish and C . Rosen, The Vaporisation and Physical Properties of Certain Refractories, Part I, WADD-TR- 60-463, Oct. 1960

IZ M. B. Panish and L. Reif, J. Chem. Phys.,

13 A. A. Hasapis, A. J. Melveger, M. B. Panish, L. Reif and C. L. Rosen, The Vaporisation and Physical Properties of Certain Refrac- tories, Part 11. WADD-TR-60-463, Oct. 1962

14 R. W. Roberts, Brit. J. Appl. Phys., 1963, 14,

15 R. W. Roberts, Trans. Faraday Sot., 1962,

16 L. H. Dreger and J. L. Margrave, J . Phys.

r7 M. €3. Panish and L. Reif, J. Chem. Phys.,

18 D. R. Stull and G. C . Sinke, Thermodynamic Properties of the Elements, American Chemical Society, Washington, D.C., 1956

19 L. Brewer, Paper No. 3, Chemistry and Metallurgy of Miscellaneous Materials, edited by L. L. Quill, McGraw-Hill Book Co, New York, I950

20 E. Anderson and W. Hume-Rothery, J . Less Common Metals, 1960, 2, (6), 413-450

21 D. A. Robins, J. Less Common Metals, 1959,

22 W. Hume-Rothery and B. R. Coles, Advances

23 P. W. Bridgman, The Physics of High Pres-

24 R. E. Honig, R.C.A. Rev., 1962, 23, (4),

SOC. A.I.M.E., I9581212,115

1961,34,(6), 1915

(91,537

58, 11.59

Chem., 1961,65, (II), 2106-2107

1962,37, (I), 128

I, 396-410

in Physics, 1954,3, (10) 149-243

sures, 1949, G. Bell, London

567-586

Co-precipitation of Alloy Powders Co-precipitation or co-reduction of two or

more platinum metals from mixed solutions of their salts has been widely practised in the past but there are few records of any study of the structure of the resulting powders.

I n a letter to Nature (1964, 203, 857) Eugene L. Holt, of Esso Research & Engineer- ing Co, reports on the examination of some platinum-gold, platinum-iridium and palladium-gold powders made by reducing mixed o.gM chloride solutions with 1.8gM sodium borohydride solution at 50°C. The powders precipitated from platinum-gold solutions had compositions corresponding

closely to those of the solutions from which they were formed and X-ray analyses indicated them to have the structure of a uniform solid solution of the two metals. Solid solution powders containing 40, 60 and 80 per cent of gold were made in this manner.

Powders precipitated from platinum-iridium solutions, however, contained appreci- ably less iridium than the solutions from which they were precipitated and the powders from solutions containing 80 per cent of iridium, for example, showed two sets of X-ray patterns indicating the presence of a platinum-rich alloy and an iridium-rich alloy.

Platinum Metals Rev., 1964, 8, (4) I40

Activated Platinum Surfaces ELECTROCHEMICAL STUDIES OF TREATED ELECTRODES

Overvoltage efects at platinum electrodes may often be reduced by “activating” the surfaces by alternate oxidising and reducing treatments. The

activity” so produced soon deteriorates, and the phenomena are now ascribed to a thin unstable layer of disoriented platinum atoms which are formed on the surface and then rapidly reorient themselves.

C b

It is well recognised that the behaviour of a pure platinum electrode in many electro- lytes is influenced in a subtle and imperfectly understood manner by the character of the platinum surface. In particular, the over- potential that must be applied in an electrochemical process may be greater for a clean smooth reflecting platinum surface than for one that has been first oxidised (generally by the action of anodically liberated oxygen in an electrolytic cell) and subsequently reduced either electrochemically or chemically.

The oxidising treatment is simple and there is general agreement that it can be quickly achieved in a reproducible manner. The surface of a platinum electrode is readily oxidised by introducing the specimen as anode in a cell containing an electrolyte such as pure dilute sulphuric acid and passing a current of about 25 milliamperes for about 5 seconds. A covering of oxide is immediately formed and rapidly builds up to a remarkably steady maximum. A completely oxidised platinum electrode has been calculated to have 1.3 x I O - ~ micro equivalents of platinum oxide per square centimetre of surface area.

Among the earlier workers who have studied activated platinum surfaces J. J. Lingane ( I ) is particularly associated with the view that their special characteristics are due to the retention after reduction of a small quantity of oxide in the coating. Lingane assumed that the residual oxide was reduced with much more difficulty than the majority of the platinum oxide. Later F. C. Anson (2) presented evidence which indicated that the

small wave which they both noted at the foot of chronopotentiograms is due not to platinum oxide but to the presence of freshly formed finely divided platinum metal, the results of alternately oxidising and reducing a platinum electrode. Anson emphasised that a layer of finely divided platinum so produced must be extremely thin. If such a layer is present it must surely increase the true surface area, but he points out that the effect of this will be observable only if the depths of the hills and valleys are of the order of the diffusion layer in thickness. It is evident that their depths are not so great as this since no effect attributable to an increase in surface area has yet been noticed.

A Japanese investigator, S. Shibota (9, has independently suggested that when an electrode is oxidised and then reduced a thin layer of “unstable platinum atoms” may be formed. The novel feature of Shibota’s proposal is that he supposes that these unstable surface atoms, which account for the high activity of the treated platinum surface, quite rapidly aggregate and presumably start to recrystallise at ambient temperatures. This conception has been developed in order to explain the large drop in activity of an activated platinum surface if it is allowed to remain for a short time in a completely oxygen-free pure electrolyte.

Two investigators at the University of California, William G. French and Theodore Kuwana (4, have now studied more in- tensively some of the consequences of this view, which they have accepted to the stage

Platinum Metals Rev., 1964, 8, (41, 141-142 141

of introducing a new symbol, Pt*, which they use to designate an “activated” or “platinised” surface.

In order to establish whether the film formed by activation is metallic platinum (rather than a mixture of metal and oxide), the approach which they adopted was to measure in coulombs the energy consumed first in the oxidation of the platinum and then in the reduction of the platinum oxide. A special quartz cell was used for the chronopotentiometric measurements, and elaborate precautions were taken to degas the cell and its contents before each test and to guard against any leakage of air.

Cyclic Activation The platinum surfaces were activated by

cycling clean platinum foil or wire electrodes between o and 1.00 volt in IF H,SO, or between -0.50 and + 0.50 volt in IF Na,CO, solution that had previously been degassed. After ten to fifteen cycles a steady state was reached. The shape of the polarisation curves was on the whole reproducible, and was independent of speed of the scan rate between 0.13 and 0.195 volt per second.

It may be helpful to note that the nomen- clature “ I F H,SO,”, which appears to be increasingly favoured by many chemists in America, probably refers to a concentration of I formula gram weight of sulphuric acid in I kilogram of solution. There seems to be no general agreement here, however, and in some instances the expression is used to refer to a solution of I formula gram weight with I kilogram of water.

A freshly activated platinum surface, it was confirmed, behaves in a remarkable and characteristic manner when used as a cathode in either dilute sulphuric acid or dilute sodium carbonate solutions. As the potential is increased, there is a sudden surge of current which then falls away just before the voltage is reached at which hydrogen is evolved. This is the chronopotentiometric prewave rccognised by several previous workers.

By using a somewhat complex cycling technique, French and Kuwana have been successful in measuring the total energy involved both in oxidising and in reducing the oxide films and show that the average ratio is essentially unity - the average of a number of tests in both solutions being reported as o.g70+0.050. This seems to dispose of the view that the reduced surface layer contains residual oxide,

Deterioration of Activity Further tests were made to determine the

rate at which an activated platinum surface deteriorates when allowed to remain in a pure and thoroughly degassed solution. Here, again, a cycling technique was used, and it is shown by a number of careful tests that the return to a more stable thermodynamic state is very rapid. The average half-life of the activated surface state is recorded as of the order of 46 minutes only.

All these results lead the authors to the conclusion that on the surface of an activated platinum electrode there is a “truly dis- located” layer of metal, either atomic in form or consisting of very small crystals. On standing, these are thought to migrate by surface movements and by reorientation to fit into a larger crystalline lattice below.

In many respects this somewhat unso- phisticated view of the nature of the surface of an activated platinum electrode invites comparison with the conception of amorphous layers fashionable half a century ago. Shibota in Tokyo in 1963 may seem a far cry from Sir George Beilby in his garden workshop in Glasgow in 1903; but there are interesting parallels between the mental approach of each, working in their different fields, to the surface mobility of metal atoms.

J. C. C.

References 1 J. J. Lingane, J . Electroanal. Chem., 1961, 2,

2 F. C. Anson, Anal. Chem., 1961, 33, 934 3 S. Shibota, Bull. Chem. SOC. Japan, 1963, 36,

4 William G. French and Theodore Kuwana,

296

525

J . P h y . Chem., 1964, 68, 1279


The Platinum Metal Phthalocyanines THE PREPARATION AND CHARACTERISTICS OF THE PURE COMPOUNDS

By I. M. Keen, Ph.D. Research Laboratories, Johnson Matthey & Co Limited

The likelihood that the platinum metal phthalocyanines might prove to be of commercial importance as homogeneous catalysts as well as of academic interest prompted an investigation into the preparation of these compounds and their subsequent characterisation.

Phthalocyanine is a deep blue-green pigment in which it has long been known that it is possible to replace two hydrogen atoms by a metal to form compounds having a similar distinctive colour. Iron phthalocyanine was discovered in 1928 at the Grangemouth works of Scottish Dyes Ltd, where it had been formed accidentally during the preparation of phthalimide from phthalic anhydride and ammonia in an iron vessel. Its structure was elucidated by Professor R. P. Linstead and his co-workers (I) between 1929 and 1934, and they coined the name now accepted. Copper phthalocyanine, the first dye of this type to be made commercially, is better known as Monastral Fast Blue BS. Greener shades of this dye may be produced by chlorinating the phthalocyanine skeleton. Some of the metal phthalocyanines have been found to have interesting catalytic applications as well as semi- and photo-conducting properties. There is thus a possibility that the platinum metal phthalocyanines might be of significant commercial as well as academic interest and the Johnson Matthey Research Laboratories have been investigating the preparation of these compounds in a pure form.

Pt (11) phthalocyanine is readily made by the process described by Linstead and his co-workers by reacting platinous chloride PtCl, with o-dicyanobenzene, C,H,(CN) , at 280 to 300°C. The resulting compound can be recrystallised from hot I-chloronaph-

thalene and is readily soluble in and recover- able from concentrated sulphuric acid. In this way crystals of the pure compound can be grown and made available for study.

The structure (2) of this compound is shown in Fig. 2. This should be compared with Fig. I, which represents the structure of phthalocyanine, C,,H,,N, (or PcH, where Pc is equivalent to C,,H,,Ns). It will be seen that a platinum atom replaces the two imino- hydrogen atoms (*). The inner square (side 2.7 A, diameter 3.82 A) of nitrogen atoms can accommodate the largest of metal atoms, e.g. platinum (diameter 2.8 A) without undue strain.

When palladous chloride is reacted in a similar way, however, palladous mono- chlorophthalocyanine PdPcCl is formed. In this compound, the palladium atom (like the platinum atom considered above) replaces the two imino-hydrogen atoms in the molecule; but in addition a chlorine atom attaches itself to the phthalocyanine skeleton. PdPcCl can be recrystallised to yield a pure product.

The position with regard to the other platinum metals is more complex and the literature on their structure is confusing (3). Recent work in these laboratories has, however, thrown considerable light on the nature of the reactions.

When rhodium trichloride RhC1, is treated with o-cyanobenzamide at about 280°C the


Fig. 1 Metal free phthalocyanine

product is a chlor-rhodium phthalocyanine PcRhC1, the chlorine being directly bound to the metal in its normal valence state. This compound cannot be crystallised but can be purified by extracting impurities consecutively with alcohol, benzene and acetone.

The other three platinum metals, iridium, ruthenium and osmium, do not appear to form metal chlorphthalocyanines. When the chlorides of these metals are treated with either o-cyanobenzamide or o-dicyanobenzene at about z80"C the products after extraction with alcohol, benzene and acetone are of a "solvated" type and have the compositions PcIrClC,H,(CN),, PcRuCl C,H,(CN), and PcOsCl,C,H,(CN)2 respectively. The complex character of these compounds is confirmed by the fact that the dicyanobenzene can only be removed by strong heating below about 500°C and that it can be replaced with aniline by boiling in that solvent.

These solvated iridium, ruthenium and osmium phthalocyanines are sparingly soluble in such common solvents as acetone, alcohol, benzene and ether and yield intensely coloured solutions having characteris tic visible absorption maxima.

It has been reported by Russian workers that the osmium tetroxide-o-dicyanobenzene


Fig. 2 Platinum (11) phthalocyanine

reaction gives a dark blue pigment whose extraction with and reprecipitation from concentrated sulphuric acid yields a polymer

Re-examination of the main reaction product in our research laboratories has shown, however, that it is a derivative of osmyl phthalocyanine, PcOs(V1)O z. C&,( CN) Boiling aniline converts this to the ammine, PcOs0,.3C6H,NH,. Treatment of either derivative with concentrated sulphuric acid could give (PcOs(VI)O.SO,). Full details of all this work will shortly be published else- where.

Now that methods of making these organometallic compounds reproducibly have been worked out and their properties have been established, it is hoped that more investigators will be encouraged to make use of their peculiar characteristics in a wide field of chemical research.

(Pcos(Iv)o.so,o),.

References I P. A. Barrett, C. E. Dent and R. P. Linstead,

J . Chem. SOC., 1936, 1719 2 J. M. Robertson et a1,J. Chem. SOC., ~935 ,615;

3 B. D. Berezin, Dokl. Akud. Nauk SSSR, 1963,

W. Herr, 2. fiir Natiirforsch, 1964, ga, 180 B. D. Berezin and N. I. Sosnikova, Dokl. Akad.

1936, 1195; 1937, 219; 1940, 36

150, I939

Nauk SSSR, 1962, 146, 604

Calibrating Platinum Thermocouples A PRACTICAL METHOD BASED ON THE FREEZING POINTS OF BASE METALS

The use of platinum : 10 per cent rhodium- platinum and platinum : 13 per cent rhodium- platinum thermocouples is widespread throughout industry for the continuous measurement of temperatures up to 1400°C and for short periods up to 165oOC. Both rhodium and platinum can be refined to very high states of purity, which enables the accuracy and reproducibility of new thermocouples to be guaranteed. But when industrial processes require precise temperature control the thermocouples must be recalibrated periodically because, even in the absence of contaminants, there is some slight drift from calibration after prolonged use, caused by rhodium migration from the alloy to the pure limb of the thermocouple.

Three methods are in general use for the recalibration of thermocouples after use. These are: comparison with a thermocouple of known calibration; the wire bridge method, involving calibration at the gold point (1063"C), the palladium point (1552'C), or the platinum point (1769°C); or taking cooling curves of pure metals with known freezing points, for example, aluminium (660°C) and silver (960.8"C).

However, works laboratories do not always possess high temperature furnace facilities which would enable them to recalibrate accurately at the gold, palladium or platinum points, and to meet these conditions. W. Heyne (I, 2) of the Deutsche Amt fur Messwesen und Warenprufung, Berlin, has now reported the use of three relatively easily obtained fixed points in a modification of the freezing point method. In this method

the thermal e.m.f.-temperature relationship of the thermocouple under test is determined by reference to the freezing points of copper (1083"C), zinc (419.5%), and aluminium. The method is independent of any standard thermocouple and is therefore unaffected by the stability of another instrument.

Heyne claims that his apparatus permits the calibration of platinum : 10 per cent rhodium-platinum thermocouples from o to 1300°C. Values of the thermal e.m.f. E(t) obtained at the freezing points enable the constants to be determined in the equation :

E(t) = a t bt - I ctZ

which governs the thermal e.m.f.-temperature


relationship over this range. From this equation calculation gives the e.m.f.s at 50°C stages up to 13ooOC. Linear inter- polation between the points so derived is not more than I p.V in error, which represents an insignificant error in the temperature reading obtained from the thermal e.m.f.

I t will be noticed that Heyne's upper fixed point is only 1083"C, which is well below the 1300OC he claims as the upper limit of calibration by this method, but he shows that the maximum error obtained during extra- polation of results to cover this region is only f 2' C. Systematic error between 300" and 13ooOC is barely o.IOC which is well within the uncertainty limit of o.s0C.

Heyne's apparatus, developed for this work, consists of a graphite crucible to contain the molten metal specimens, which are copper, aluminium or zinc of a known high degree of purity. These metals are prevented from oxidising, which would affect their freezing points, by maintaining a reducing atmosphere in several graphite chambers above the crucible. The thermocouples to be tested are

protected by surrounding them with a gas- tight tube of pure sintered alumina before insertion in the apparatus. Three thermocouples can be tested simultaneously by using a graphite block as the crucible with three equaIly spaced holes for the molten specimens.

Heyne points out that his method, although similar in many respects to previous work, offers advantages over the Russian method using antimony in place of aluminium and is simpler than the NBS method using four fixed points (3).

This method of calibration for thermocouples appears to offer a convenient way of checking their accuracy after prolonged service at high temperatures when some drifting is suspected. The apparatus is simple and the freezing points of copper, aluminium and zinc are not difficult to obtain.

F. J. S.

References I W. Heyne, Feingerutetechnik, 1964, 13, (7),

2 W. Heyne, Experini. Techn. Physik, 1964, 12,

3 NBS Tech. News Bull., 1961, (March), 44-48

3 11-3 15

( 2 ) Y 90-99

Platinum Films as Temperature Probes FRENCH STUDIES ON AVIATION AND ROCKETRY APPLICATIONS

Increasing efforts by the French aviation industry to develop new aircraft and rockets have led to a considerable volume of research on all aspects of engine design.

Powder propellants present special probems of ignition and to monitor the ignition of powder composites by shock-waves a probe with fast temperature response is needed which also can resist the high temperatures and chemical conditions which may occur.

M. Scagnetti and J. Crabol have described such a probe in La Recherche Adrospatiale, 1963, (November-December), 23-30. It consists of a platinum fdm deposited on a silica support which then is incorporated in the wall of the shock-tube so that it is exposed to the same heat flux between powder and ignited gas as the rest of the tube. It is necessary to allow for the difference between the materials which make up tube and probe

and the article explains how this can be done.

The probes are part of a modified bridge circuit and register changes in heat flux as small changes in voltage. These can be converted easily to temperatures in degrees Centigrade and show how the temperature varies continuously over the first millisecond after ignition. A series of probes is used along the length of the shock-tube to study variations at different distances from the orifice.

C. Vautier and A. Colombani (Compt. rend., 1964, 258, (IS), 4706-4709) also report that platinum films act as fast and accurate resistance thermometers over the range from o to 500°C. Their films were different in that they were deposited on tungsten filaments but their work confirms that there is considerable scope for further developments in the use of platinum films for temperature measurement.


ABSTRACTS of current literature on the platinum metals and their alloys PROPERTIES The Properties of Platinum-Cobalt Magnets Produced by Powder Metallurgy H. c. ANGUS, Powder Metallurgy, 1964~7, (13)~ 1-12 Co-Pt alloy magnets prepared from Pt and Co powders are superior to those prepared by melting. Fabrication and testing are described. Careful heat treatment is vital. The equiatomic stoichio- metric alloy gives the best results. Energy products >IO: gauss-Oe and coercive forces up to 4900 Oe have been obtained.

The Magnetic Structure of Copt B. VAN LAAR, J. Physique, 1964, 25, (s), 600-603 X-ray diffraction showed that tetragonal Copt has a -2.677 A, c=3.685 8. Magnetic moments point along the c-axis. Co at (0, 0, 0) and Pt at (i, +, 4) are coupled ferromagnetically.

Ordering in Copt-CrPt and Copt-MnPt Alloys J. c. WOOLLEY, J. H. PHILLIPS and J. A. CLARK, J. Less-Commotz Metals, 1964, 6, (6), 461-471 Ordering effects in the Co-Cr-Pt system were studied by taking CoPt-CrPt alloys with equal increments of composition and determining lattice parameter values for ordered and disordered structures, and by X-ray methods estimating ordering temperatures and the type of ordering reaction. Similar studies on the Co-Mn-Pt system showed that alloys containing >20 at.:" Mn do not have the Copt-type ordering reaction.

Relations between the Structures of Phases in the System Platinum-Molybdenum H . P. ROOKSBY and B. LEWIS, J . Less-Common Metals, 1964, 6, (6), 451-460 Crystal structure changes occurred in Pt-coated Mo wire above 800°C as Mo diffused into Pt, forming successively the intermediate phases $-Pt,lMo, y-Pt,Mo, 8-Pt,Mo, and c-PtMo,.

The System Platinum- AIuminium R. HUGH and W. KLEMM, 2. anorg. al[gem. Chew.,

X-ray and thermal analyses revealed the inter- metallic phases 'PtA12, PtAI,, PtAl,, Pt,Al,, PtAl, Pt,Al,, Pt,Al,, Pt,A1 and Pt,,Al,. Pt,Al, has hexagonal Ni,Al,-type structure with a =

4.209, c=10.35 a. Pt,Al, has rhombic Th,Ge, structure with a=5.4rY b=10.70, ~'3.95 A. Pt,Al has cubic Cu,Au-type structure with a = 3.876 8. Molecular volumes are discussed. Pt-rich alloys contract strongly; Al-rich alloys dilate strongly.

1964,329, (I-@, 123-135

Lattice Constants and Thermodynamic Parameters of the Hydrogen-Platinum- Palladium and Deuterium-Platinum-Pallad- ium Systems A. MAELAND and T. B. FLANAGAN,J. Phys. Chem.,

Absorption isotherms at 25°C and thermodynamic parameters of D, absorption were measured for o,2.79, 5.73,8.80 and 12.03",/0 k - P d alloys. The effect of D, content on the relative resistance of the alloys was compared with data from the H-Pt-Pd system.

The Palladium-Uranium Phase Diagram up to 25 at.04 Uranium G. P. PELLS,J. Inst. Metals, 1964,92, (12), 416-418 X-ray diffraction and metallographic studies of U-Pd alloys with <25 at.0; U showed two eutectoidal transformations: at 13.5 at. U, 694°C givingPd,,U, andPd,,U,; at 15.5 at.;& U, 1015°C giving Pd,,U, and Pd,U. Pd,U formed peritectically at 18.8 at.o/, U, 1440°C. Pd,,U,, Pdl,U, and Pd,U, have non-cubic structure. They and Pd,U,formedperitecticallyat 21 at.:;; U, 1525OC with Cu,Au-type structure, all have small solubility ranges. Pd,U was detected above 20.8 at.%U. The variation of electrical resistivity with composition was determined up to 15.5 at.?<> U.

Melting Equilibrium in the Ternary System Cobalt-Manganese-Palladium G. ZWINGMANN, Metall, 1964, 18, (7), 708-710 Thermal analysis and metallographic examination of the Co-Mn-Pd system showed that the two Mn-Pd eutectics are joined by a continuous series of eutectics in the ternary region with temperature minima at 1140 and 1z1o"C on either side of a maximum at 1330°C. Less than 39/0 Co is soluble in p-phase alloys.

The Thermal Decomposition of Rhodium (111) Oxide and the Influence on Alloying with Platinum and Palladium N. G. SCHMAHL and E. MXZL, 2. phys. Chem. (Frankfwt), 1964, 41, (1-2L78-96 The decomposition of Rh,O, at 900-1100°C was studied. R h o and RheO were not detected but Rho, evaporated from Rh. The temperature dependence of the layer on Rh affected by 0, was studied. Pt powder additions to Rh,O, showed that the 0,-pressure from decomposition was a function of Rh-Pt alloy composition but was only slightly temperature-dependent. Results were discussed in relation to NH,-oxidation at Rh-Pt contacts and to thermocouple oxidation. The Rh-Pd-0, system was also tested.

19641 68, (61, 1419-1426


The Constitution Diagram Tantalum- Rhodium B. c. GIESSEN, H. IBACH and N. J. GRANT, Trans. Met. SOC. A.I.M.E., 1964, 230, (I), 113-122 The system was studied by X-ray and metallographic methods and by thermal analysis. Five intermediate phases were detected : 0, tetragonal FeCr-type; al , orthorhombic; a2, orthorhombic Co,Si-type; a,, structure unknown, a-TaRh,, cubic AuCu,-type. 4, al, a2 and r3 melt peritectically and a-TaRh, has a maximum melting point.

New Intermediate Phases in Systems of Nb or Ta with Rh, Ir, Pd or Pt B. c. GIESSEN and N. J. GRANT, Acta Cryst., 1964, 17, t5),615-616 The existence of 18 new phases in these systems is reported, together with data on their crystal structures.

The Osmium-Iridium Equilibrium Diagram R. D. REISWIG and J. M. DICKINSON, Trans. Met. SOC. A.I.M.E., 1964, 230, (3), 469-472 The Os-Ir equilibrium diagram exhibits a peritectic temperature of about 2660°C with a miscibility gap between 42 and 63 wt.@/, 0 s . Two- phase specimens near the boundaries of the miscibility gap led to the discovery of Widmans- taetten figures and accounted for a previously suspected transformation. (7 figs.)

The Ruthenium-Iridium Alloys E. RAUB, Z. Metallkunde, 1964, 55, (6) , 316-319 The high mutual solubility of Ru and I r was indicated by X-ray and metallographic studies, with the binary phase at 2o0o1'C extending from 46 to 52 at.:, Ir. Ir-rich solid solutions showed greater temperature dependence of the solubility curve. Completely homogeneous supersaturated alloys cannot be obtained by cooling from high temperatures. Secondary spectral bands for Ru- rich phase alloyed with 55 at.';,, Ir are due to spinodal decomposition to an extent depending on the treatment.

The Palladium-Iridium Alloys E. RAUB and E. ROSCHEL, Ibid., 320-321 X-ray and metallographic studies confirmed that Pd-Ir solid solutions do not form from the melt by a peritectic reaction. A continuous series of solid solutions exists from the miscibility gap to the liquid state.

The Structure of Solid Iron-Iridium Alloys

367-370 An h.c.p. phase in the Fe-Ir system was found by X-ray diffraction. Transformation occurred at about 470cC, 19 at.();, Ir. Maximum formation temperature was 625"C, 38 at.:: Ir. The phase showed a wide range of homogeneity.

E. RAUB, 0. LOEBICH and H. BEESKOW, Ibid., (7),

The Constitution Diagram Tungsten-Ruthen- ium E. J. RAPPERPORT and M. F. SMITH, Trans. Met. Soc. A.I.M.E., 1964, 230, (I), 6-11 The system was studied by X-ray and metallographic methods and by electron microprobe analysis. Terminal solid solutions have 23 at.% maximum solubility of Ru in W at 2300°C and 48 at.Oi, W i n Ru at 2205°C. Solubilities decrease at lower temperatures. a-phase W,Ru2 forms peritectically at 2300°C and decomposes eutectoid- ally at 1667T to a-W and p-Ru. An eutectic occurs at 45 at.".:, Ru, 2205°C and yields 0-phase and P-Ru.

Vapour Pressures of Ruthenium and Osmium N. J. CARRERA, R. F. WALKER and E. R. PLANTE, J . Res. Nut. Bur. Stds., Pt. A, 1964, 684 (3>, 325-330 A modified Langmuir method with a micro- balance technique measured the vapour pressures of Ru and 0 s and their heats of sublimation at 298'K. For Ru: log Patrn-7.5oo - 32,769/T at 1940-2377~K; AH",(298)=156.1+ 1.5 kcal/mole; the boiling point is 4150&1oo'K. For 0 s : log Pat, =7.484 -39,88o/T at 2157 - 2592'K; AHC, (298)-18g.o~1.4 kcal/mole; b.p. is 5300&1oo'K.

Some Experiments on the Osmium-Carbon and Ruthenium-Carbon Systems B. JEANTET and A. G. KNAPTON, Planseeber. Pulver- met., 1964, 12, (I), 12-18. Attempts to prepare carbides of 0 s and Ru were unsuccessful. Doubt is cast on the report of their preparation by Kempter and Nadler.

Mechanical Properties of Several Nickel- Platinum-Group Metal Alloys w. L. PHILLIPS, Trans. Met. SOC., A.I.M.E., 1964,

Tension tests at 25, 500, 800 and IOOO"C and stress-rupture tests at 650 and 800°C on 0.5, 2.0 and 6.0 at.'X Os-, I'd-, Ru-, and Rh-Ni alloys showed that room- and elevated-temperature tensile strengths, as well as stress-rupture life, increase at the same Pt-metal content in the order Pd, Rh, Ru, 0 s . Ductility decreases with increasing Pt-metal content or with temperature at a given concentration of Pt-metal. These results are discussed in relation to solid-solution theory.

Specific Heats and Magnetic Susceptibility of Superconducting Binary Complex Phases of Transition Metals E. BUCHER, F. HEINIGER and J. MULLER, Pkys. kondens. Materie, 1964, 2, (3), 210-240 Measurements are described and results presented for 15 phases with a- and X-structures both in the normal and in the superconducting states. Among the alloys are phases from the systems Nb-Os, Nb-Rh, Nb-Ir, Nb-Pd, Nb-Pt, Mo-Ru, Mo-0s and W-Ir.

230, (311 526-529


ELECTROCHEMISTRY A Simple Method for Determining the Cleanliness of a Platinum Anode s. SCHULDINER and T. D. W A R N E R , ~ . Phys. Chem.,

The linearity of the voltage-time curve in the atomic 0 adsorption region can serve as a reliable index of electrode cleanliness. Oscilloscope traces illustrate this for a Pt bead electrode in I MH,SO,. The true area of the clean Pt electrode can be derived also.

The Relative Electrocatalytic Activity of Noble Metals in the Oxidation of Ethylene H. DAHMS and J. O'M. BOCKRIS, J . Electrochem. soc.,

Complete anodic oxidation of C,H4 to CO, occurred at Pt, Ir, and Rh electrodes but on Au and Pd the main products were aldehydes and acetone with hardly any CO,. The electrolyte was I M H,SO, a t 8o'C and the cell is described. The orders of reactivity for the two groups of electro- catalysts were Pt,>Rh: Ir and Pd>Au.

The Mechanism of the Electro-Oxidation of Acetylene on Platinum J. w. JOHNSON, H. WROBLOWA and J. O'M. BOCKRIS, Ibid., (7), 863-870 Parameters for C,H, oxidation on platinised Pt gauze electrodes were determined at 80°C in solutions of H,SO,-I Na,SO, and NaOH of constant ionic strength. Reaction rates depended on potential, pH, and p c , ~ , . Coulombic efficiency, measured as CO, production in acidic solutions and C,H2 production in alkaline solutions, was roo3 I"(> in acid, 95 t 5 " J o in alkali. Heats of activation and passivation effects were also measured.

Hydrogenation of Ethylene at Palladised Palladium and Platinised Platinum Elec- trodes L. D. BURKE, c. KEMBALL and F. A. LEWIS, Trans. Faraday SOC., 1964, 60, (5), 913-918 Hydrogenation of Acetylene at Palladised Palladium and Platinised Platinum Elec- trodes L. D. BURKE, F. A. LEWIS and c . KEMBALL, Ibid., 919-929 Electrocatalytic hydrogenation of C2H4 and of C,H, dissolved in aqueous solutions of HCI and NaOH was measured at 25 and 5oOC and results compared, using H, preadsorbed on Pd as well as electrolytic H,. C,H, was produced from C,H, and CzHs and C2H4 were produced from C,H,, as shown by gas chromatography. Electrolytic H, was most efficient with C,H, at palladised Pd electrodes in alkaline solution. C,H, was reduced to C,H, at a rate dependent on olefin diffusion through the Brunner-Nernst boundary layer on the electrode surface.

1964, 68, (5h 1223-1224

1964, 1113 (6)3 728-736

ELECTRODEPOSITION AND SURFACE COATINGS Vapour Deposition of Pure Ruthenium Metal from Ruthenocene D. E. TRENT, B. PARIS and H. H. KRAUSE, InOrg. Chem-, 1964,3, (7), 1057-1058 99.999; pure Ru film was deposited from bis- (cyclopentadienyl) ruthenium at 595°C in a stream of Hz on the inside of a Vycor tube in which the reaction took place. Ruthenocene, which has an appreciable vapour pressure at relatively low temperatures, was carried by the gas stream to the point of deposition. A non-uniform deposit formed on the graphite susceptor used for heating.

LABORATORY APPARATUS AND TECHNIQUE

The Weight Constancy of Rhodium and Iridium \ressels during Analytical Operations G . REINACHER, Werkstoffe u. Korrosion, 1964, 15, (613451-457 Rh and I r crucibles plated with Pt and unplated were tested in various analytical operations. Unplated vessels were tarnished after heating at 800-IOOO'C. Rh had gained some weight at IOOO-C but Ir tended to lose it by 903-C. Both resisted attack by HNO, and HC1 better than Pt. KHSO, fusion at 400°C had no effect but, at 600"C, Rh was attacked. Rh resisted attack during NaHCO, fusion better than Ir. Vessels covered with Pt had the usual good resistance of Pt.

CATALYSIS Chemisorption and Surface Chemistry of Ethylene on Supported Platinum Catalysts P. J. LUCCHESI, J. L. CARTER and J. H. SINFELT,

J. Am. Chem. SOC., 1964, 86, @), 1494-1497 Comparisons of CzHa chemisorption and surface chemistryonAI,O, and0.6 and 1.0 wt.?; Pt/A1,0, catalysts showed that identical species formed on them with different reactivities. H2 treatment removed adsorbed species more easily from Pt/A1,0, than from A1,0,, suggesting that migration of reactive species between Pt and Al,O, centres may be an important mechanism. Desorp- tion products of this treatment were mainly C,H, and n-C,H,, at IOO-I~O'C, with more CH, and C,H, at higher temperatures.

Reactions of Some C, Aromatics on Platinum-Alumina Catalysts P. E. SHEI'HAKD and J. J. ROONEY,?. Catalysis, 1964, 3, (2), 129-144 When n-propylbenzene, w-methylstyrene, and o-ethyltoluene reacted with excess H, over Pt/r-Al,O, in the range 337 to 490°C and when indane reacted at 337,392, and 434 C, equilibrium


between olefins and corresponding paraffins by hydrogenation and dehydrogenation occurred rapidly. Dehydrocyclisation of the substituted benzenes gave indane, the C , ring of which was hydrogenolysed to give the isomeric alkylbenzene without reaching equilibrium. Product analyses and tests on catalysts with varying composition, sintering and thiophene poisoning showed that the reactions depended on the state of the supported Pt.

Hydrogenolysis of Cyclopentane Hydro- carbons in the Presence of Platinum on Alumina I. v. GOSTUNSKAYA, HO CHIN-FYN and B. A. KAZANSKII, Izv . Akad. Nauk. S.S.S.R., Sw. Khim., 1964, ( 5 ) , 832-836 The hydrogenolysis of cyclopentane, methylcyclopentane, and ethylcyclopentane was studied using 9.S0, Pt/AI,O, catalyst at 230 to 280°C. Apparent activation energies were determined; for the alkylcyclopentanes these were lower than for cyclopentane itself. The products were linear and branched alkanes.

Hydrogenolysis of Cyclopentane Hydro- carbons in the Presence of Platinum Sup- ported on Silica Gel Ibid., (6), 1073-1077 The apparent activation energies of hydrogenolysis of methyl- and ethylcyclopentanes on Pt/SiO, at 21o-26o0C are less than that for cyclopentane. The deactivating effect of alkyl groups on 5- membered rings was clearly apparent.

Catalytic Conversion of Cyclopentane and its Homologues in the Presence of Platinum Supported on Aluminosilicate Ibid., 1078-1082 Conversions over PtjSi0,-Al,O, were studied at atmospheric pressure in the 200-270°C range. At 200-235"c hydrogenolysis of cyclopentane and methylcyclopentane was selective and the apparent activation energy of the reaction could be calculated. Ethylcyclopentane was not selectively hydrogenolysed but most of it was isomerised to methylcyclohexane. The temperature coefficient of isomerisation was less than that of dehydrogenation of methylcyclohexane. At 23O-27O0c, there was less hydrogenolysis of ethylcyclopentane as the temperature rose.

Desorption of Hydrogen from Platinum Catalysts

J . Phys. Chem., 1964, 68, (5), 1244-124s 1.15 wt.Ob Pt/AI,O,, Pt/SiO,, and Pt black catalysts all have nearly the same minimum and maximum heats of adsorption and exhibit two types of adsorption of Ha. The activation energy of desorption E for 1.15 wt.% Pt/AI,O, was almost constant at 10 kcal/mole below room temperature and rose to 23 kcal/mole at about 300°C. H z was

Y. KUBOKAWA, S . TAKASHIMA and 0. TOYAMA,

chemisorbed on the catalyst at 300"C, the catalyst was cooled in H, to -52°C and then heated in stages. At - 5 2 T the H:Pt ratio was nearly I, indicating high Pt dispersion.

On the Hydrogenation of Dimethylene- cyclobutane YA. M. SLOBODIN and A. P. KHITROV, Zh. Obshch. Khim., 1964, 34, (6), 1727-1728 During the hydrogenation over PtO, of I,Z- dimethylenecyclobutane, cis- and trans-r,z-dimethylcyclobutane were formed. Similar hydrogenation of 1,3-dimethylenecyclobutane caused some breaking of the +membered ring and the formation of 2-methylpentane.

Catalytic Reduction of Aromatic Nitrocom- pounds. XIV. Reduction of Nitrobenxene on Platinum Black v. P. SHMONINA, Ibid., 2020-2026 Nitrobenzene was reduced over Pt black in tests in the range o-so'C, 40-80';(, C,H,OH solution. Addition of 0.1 N KOH or 0.1 N HCl to the solution retarded the reaction.

Tritium-labelling of Natural Products R. MAURER, M. WENZEL and P. KARLSON, Nature, 1964,202, (4939, 896-898 Tritiation of pure digitogenin by the charcoal adsorption method combined with Pt catalysis was almost IOO times faster than by the Wilzbach technique at room temperature and gave specific activities three times better than with charcoal adsorption alone. Digitogenin in CeH,/C2H,0H was shaken with I O : ~ Pt/C, exposed to 2c T, for 7.5h, separated and tested.

Shifts of Double Bonds in Hexenes in the Presence of Platinum Catalysts

LEONOVA, I. v. GOSTUNSKAYA and B. A. KAZANSKII, Neftekhimiya, 1964, 4, (2), 215-218 Catalytic isomerisation under partial hydrogenation conditions by Pt black and Pt/C was studied on hexenes with double bonds in the a-position (hexene-r ; 2-, 3- and 4-methylpentene-I; 2,3- dimethylbutene-I). Different forms of H, are believed to cause double-bond transfer and hydrogenation. Isomerisation increases when more H, dissolves in the catalyst metal; hence Pd is more active than Pt.

Catalytic Conversions of Spiro-(5, 6)-dodecane on a Platinum Catalyst

N. B. DOBROSERDOVA, G. S . BAKHMET'EVA, A. I.

N. V. ELAGINA, A. K. MIRZAEVA, KH. E. STERIN, A. V. BOBROV and B. A. KAZANSKII, Ibid., 241-245 660,; of spiro-(S, 6)-dodecane was converted over Pt/C at 320°C. C-C bond rupture occurred at the quaternary C atom, followed by isomerisation and dehydrogenation. Principal product was diphenyl, produced by dehydrogenation via dicyclohexyl. Minor products were n-hexylbenzenc, benz- cycloheptane and I, 2-benzbicyclo-(o,3,3)-octane.


On a Series of Hydrogen Additions to Double Bonds of 4-Vinylcyclohexane-1 on Pt- and Ni Catalysts

B. A. BELINKOVA, Ibid., (3), 382-385 When 4-vinylcyclohexene- I was hydrogenated over Pt /C and Raney Ni the first double bond affected was that outside the ring. Product ratios of 4-ethylcyclohexene- I and ethylcyclohexane were -3:r on Pt/C and -9:r on Raney Ni.

Catalytic Conversion of 1,l-Dimethyl-cyclohexane on Platinum Catalyst at Elevated Temperature and Hydrogen Pressure S. I. KHROMOV, D. CHULTEM and E. s. BALENKOVA, Ibid., 413-416 Toluene was the principal product of conversion of I, I-dimethylcyclohexane over roc, Pt/C at 320 and 460"C, and 20 atm H,. Meta- and ortho- xylene were the chief products over I": PtfA1,0, at 400-460"C, and 20 atm H2.

Catalytic Conversion of n-Amylbenzene on Platinum Catalyst

A. v. BOBROV and B. A. KAZANSKII, Ibid., 417-420 n-Amylbenzene was dehydrogenated over 15 ":I P t /C at 32oCC and converted into E-ethylindane, a-methylnaphthalene, 8-methylnaphthalene and naphthalene, which were determined by chromatography.

Olefin Isomerisation with Noble Metal Catalysts J. FALBE and F. KORTE, BrennstofJ-Chem., 1964,45, (4)3 103-105 Pd/C and PtlC were shown to be good catalysts for the isomerisation of butene-2 and pentene-2 to mixtures of the corresponding olefin isomers. The amount of isomerisation of pentene-2 using RhCl, and IrC1, as catalysts during the formation of CO-compounds of Rh and I r was also studied.

Stereoisomeric Conversion of Individual cis- and trans-3-Methylpentene-2 in Liqnid Phase Catalytic Hydrogenation Conditions I. v. GOSTUNSKAYA, A. I. LEONOVA and B. A. KAZANSKII, Neftekhimiya, 1964, 4, (3), 379-38 I Isomerisation of each of cis- and t~uns-3-methylpentene-2 in alcoholic solution increased with catalysts in the order Pt<Ni<Pd. Low boiling- point isomers reacted faster than those of higher boiling-point. Minor products included 3- methylpentane and 2-ethylbutene-I.

Homogeneous Catalysis. I. Double Bond Migration in n-OIehs, Catalysed by Group VIII Metal Complexes J. F. HARROD and A. J. CHALK, J . Am. Chem SOC.,

Catalysis of double bond migration in linear olefins by Pt metal complexes yielded equilibrium

L. KH. FREIDLIN, A. F. PLATE, I. F. ZHUKOVA and

A. K. MIRZAEVA, N. V. ELAGINA, KH. E. STERIN,

1964,86, (91, 1776-1779

distribution of isomers. The effects on reaction rates, cocatalysts, and isomer distribution of the metal ions, their oxidation state, and their ligand attachments were studied. When suitable cocatalysts were present, I-hexene was isomerised by dichlorobis(ethylene)dichlorodiplatinum(II), RhC1,.3H20 isomerised 1-hexene, cis- and trans- a-heptene, Pd(I1) complexes catalysed similar reactions until reduced to Pd, and IrC1, behaved like Pt(I1).

On the Mechanism of Hydrogenation of Dienes with Linked Double Bonds on Palladium Catalyst L. KH. FREIDLIN and E. F. LITVIN, Neftekhimiya, 196434, (31, 374-378 The composition of olefins derived from hydrogenation over Pd black of isoprene, 2,j-dimethyl- butadiene, 3-methylbutene-I, and z~-dimethylbutene-r depended on the point of H2 addition or on the amount of isomerisation before desorption at the catalyst. Olefines produced were not isomerised in the presence of the diene.

Study of the Partial Catalytic Hydrogenation of Nitrocyclohexene P. GUYER and H. J. MERZ, Chimiu, 1964, 18, (4), 144-146 When nitrocyclohexene was hydrogenated in the presence of PdlC, the double bond was attacked 7.8 times more quickly than with Pt;C, but with PtlC the NO, was reduced 1.8 times more quickly than with PdiC. Hydrogenation of nitrocyclohexane with Pd:C therefore leads principally to cyclohexylhydroxylamine but with Pt'C the reaction can be selective for cyclo- hexanonoxime.

The Activation on Palladous Chloride by Metal Ions in the Homogeneous Hydrogena- tion of Ethyl Crotonate E. B. MAXTED and s. M. ISMAIL, J . Chem. SOC., 1964,

10-4'M aqueous solutions of acetates of Cu, Ni, Zn, Ag, Hg, Cd, Na and Ca, and of chlorides of Cu, Ni, Co, Al, Mg, Ce and Cr were tested as promoters of I'!/~ PdC1, solution as catalyst for the hydrogenation of ethyl crotonate. Activation was successful at as low as 30%, I atm. Na+ was most active, increasing the activity of PdCI, by up to seven times. Decrease in activity and the precipitation of Pd as the reaction proceeded indicated a homogeneous reaction in which individual Pd atoms in PdCl, are catalysts.

Investigations of the Hydrogenation Reac- tions of Olefins and Dienes in the Presence of Rhodium Black L. KH. FREIDLIN, E. F. LITVIN and L. M. KRYLOVA, Neftekhimiya, 1964, 4, (2), 185-189 Rh black catalysed liquid phase hydrogenations of diems, (cis-piperylene, isoprene and 2,3-dimethyl-

(May), 1750-1752


butadiene) and olefines (pentene-I, cis- and trans-pentene-2, 3-methylbutene-I and 2,3- dimethylbutene- I) with selectivity close to that of Pt black and isomerisation properties (double- bond transfer and cis-trans isomerisation) intermediate to those of Pd and Pt black.

Synthesis of High-Molecular-weight Paraf- fins from Carbon Monoxide in Aqueous Suspensions of Ruthenium

Makromol. Chem., 1964, 70, 1-1 I

Paraffin waxes with melting points up to 131°C and mol. wt. up to 7000 were synthesised by feed- ing CO into an aqueous suspension of finely divided, metallic Ru at 75-200 atm, 150-260°C. AH=57.2 kcal/mole wax. I O O " ~ CO-conversion was possible. CO,, CH, and H, were byproducts. H,O acted as reactant, suspension liquid, coolant and heat transfer medium.

H. KOLBEL, W. H. E. MULLER and H. HAMiMER,

Polymethylene from Carbon Monoxide and Hydrogen H. PICHLER, B. FIRNHABER, D. KIOUSSIS and A. DAwALLU, Ibid., 1964,70, 12-22

Polymethylene, similar to low-pressure poly- ethylene, with mol. wt. up to IOO,OOO+ was synthesised from CO and H, in the presence of RuO, at high pressures below 140°C.

Hydrogenation and Hydrogenolysis. VIII. The Ruthenium-catalysed Hydrogenation of Aromatic Compounds Containing C - 0 Link- age to be Easily Hydrogenolysed Y. TAKAGI, T. NAITO and s. NISHIMURA, Bull. Chem. Sot. Japan, 1964, 37, (4), 585-587 RuO, successfully catalysed hydrogenations of compounds in which it was desired to avoid hydrogenolysis of C-0 linkages. Reactions were rapid and gave good yields of the corresponding alcohols or ethers, although slightly more hydrogenolysis occurred than with Rh and (7:3) Rh- Pt oxides as catalysts, perhaps because the latter operated at lower temperatures. Solvents were not used, except for C,H,OH or H,O with benzyl alcohol, but CH,COOH additives were used to neutralise alkaline traces in RuO,. Reac- tions took place at 95-IOO0c, 80-xoo kg/cm2 H,.

Catalysts for Selective Hydrogenation of Soybean Oil. 11. Commercial Catalysts c. H. RIESZ and H. s. WEBER, J. Am. oil Chem. soc., 1964, 41, (41, 400-403 Linolenic components of soybean oil are hydrogenated with high selectivity by commercial Pt, Pd, and Rh catalysts. Many of the latter had selectivities SL of 2.4 to 2.7, but of the Ni catalysts tested only Raney Ni had S ~ > 2 . 0 . The Pt metal catalysts isomerised the linolenic components to the trans-form to the extent 7.8 - 15.4;~ but Ni caused only 5.2 - 7.4O; isomerisation.

FUEL CELLS Electrochemical Oxidation of Methanol in Fuel Cells M. PRIGENT, Rev. Inst. Fr. Pimole, 1964, 19, (6), 1-54 The complete oxidation of CH,OH is affected by the electrode potential, reactant concentration, and the state of the catalyst electrode. Studies of these parameters showed that Pt black electrodes gave the best results. Electrode properties depended on the weight of Pt deposit, on the deposition potential, and on additives. (83 references).

Structure and Activity of a Type of Sintered Electrode for Gas Cells R. COFFRE, G. PEUILLADE and B. MICHEL, Ann. Radiodect., 1964, 18, (74), 40-59 The theoretical basis of sintered fuel cell electrodes is expounded and the efficiency, activation processes, and passivation and ageing of oxygen and hydrogen electrodes are described. Au is used as catalyst on the Ni oxygen electrodes and Pd or Pt on the Ni alloy hydrogen electrodes. The latter age as Pd or Pt recrystallises.

The H,-Cl, Fuel Cell. A Study of the Pros- pects of Power Recovery in Plants for Electrolytic Manufacture of Chlorine and Soda G. BIANCHI and c. TRAINI, Chim. e Znd., 1964, 46, (4), 363-370 (English summary) The capillary-inhibition H, electrode and the flowing-electrolyte C12 electrode were porous graphite discs activated with Pt or Ir. The electrolyte was HCI solution. Ionisation occurred at room temperature and 1000 A/mZ was obtained with 0.5 V at the H, electrode. 1000 Aim2 was reached with 0.2 V at the C1, electrode. Pure H, and dilute Cl, from the Deacon process could yield 500 AimZ at 0.88 V working voltage at room temperature and pressure. This represents 25 %, power recovery from the electrolysis but actual power recovery is less because some is used in auxiliary process equipment.

Electrochemical Oxidation of Hydrocarbons

Ber. Bunsengesell. Phys. Chem., 1964, 68, (4), 400-404 Pt/Ta screens were used in fuel cell oxidation tests at 70'C with 30:/0 H,SO, electrolyte. Current densities of 35 mA/cm2 with CH,OH fuel and 80 mA/cmz with HCOOH were achieved, both at 0.3 V. Pt black mixed with a Teflon dispersion and spread over a Ta screen was used in similar tests on CH,, C,H,, C,H,, n-C,H,, and iso-C,H,,, with 0, as oxidant and 85';;, H,P04 electrolyte. Such cells generated 40 mA/cmL at 0.37 V, 150°C using C,H, or n-C4Hlo hels.

R. JASINSKI, J. HUFF, S. TOMTER and L. SWETTE,


TEMPERATURE MEASUREMENT A Microfurnace for High Temperature Microscopy and X-ray Analysis up to 2150°C w. GUTT, 7. sci. Instrum., 1964, 41, (6), 393-394 The design, calibration and testing of an Ir:600/,

N E W P A T E N T S Ruthenium Hydrogenation Catalyst

British Patent 956,630 A catalyst of 1-5 wt.:/,, Ru on an inert carrier is used for the hydrogenation of mono- and polyhydroxy and alkoxy aromatics using H, at 25- 150°C and 50-200 p.s.i.g.

Halogenated Platinum Metal Catalysts

British Patent 956,684 A hydrogenation catalyst of improved activity i s prepared by treating an alumina-supported catalyst containing o.or-5.0 wt.yi Pt or Pd with a F compound, e.g. CF,, t o give a product containing 1.0-5.0 wt.96 F.

Platinum Metal Isomerisation Catalyst

British Patent 956,685 A catalyst consisting of an alumina support with a surface area of at least 300 m2/g, 0.1-2.0 wt.yo of Pt or Pd, up to 1.0 wt.": C1, and 1.2 x 10-~ to 3.4 x I O - ~ g F,/mZ of A1,0, surface area is used for the isomerisation of 4C and higher paraffin hydrocarbons at 250-500°c and 250-roo0 p.s.i.g.

Ruthenium Hydrogenation Catalysts

British Patent 957,149 Ruthenium metal, oxide, salt or ruthenate may be used as hydrogenation catalyst in the conversion of pyridyl-(4)-ethers to piperidyl-(4)-ethers by reaction at 130-14o"C and roo-zoo atm. H,.

Semiconductor with Noble Metal Alloy Contact Element SIGMUND COHN CORP. British Patent 957,639 A silicon diode semiconductor has a spring contact element made of an alloy containing, by weight, I-IO% W, 1-z00/, Mo and/or 1-1z0/U Cr and balance of Rh or Pd and Pt with up to 50~/~ , Pt.

Activation of Platinum Metal Electrodes

British Patent 957,703 Particularly active electrodes for use in the electrolysis of brine are produced by exposing a T i electrode plated with Pt group metal or alloy, in particular Pt, Pt-Rh or Pd-Ag, to the action of Hg vapour or alkali metal amalgam vapour, the Hg

ENGELHARD INDUSTRIES INC.

THE BRITISH PETROLEUM CO. LTD.


C. F. BOEHRINGER & SOEHNE G.m.b.H.

JOHNSON, MATTHEY & CO. LTD.

Ir-Rh thermocouple used as a microfurnace for microscopy and X-ray analysis to 215ooC are described. The electrically heated thermocouple acted as specimen holder, heater and thermometer. Variation was+o"C at zo00"C over one hour and ~ I O T at 1900°C over 12 hours. The cold junction had to be maintained at 0°C. Corrosion by specimens was resisted.

coating being distilled off after it has been deposited to leave the surface in a highly active state.

Precious Metal Alloy Electric Switch

British Patent 957,872 Electric switches for clocks and watches and the like have one contact made of an alloy containing 65-80:/~ Au and 35-20':u Ag, with up to 30":) Ag being replaceable by Cu, and a second contact made of an alloy containing 4040% Pd and 60-405;, Ag, with up to zoyo Ag replaceable by c u . Platinum Metal Anodes

British Patent 958,413 Improved anode for the production of chlorine by brine electrolysis consists of a wire mesh supported on a pillar and strengthened by stiffeners, all parts made of T i or its alloys, and an operative anode surface produced from Pt, Rh, Ir or an alloy of two or more of these metals applied to the wire mesh.

Palladium Plating

British Patent 958,685 Pd is plated on to articles forming a cathode in a bath containing 4-100 g/1 Pd, 20-160 g/l ammonium sulphate, 4-100 g/1 ammonium nitrite, 0-1 g/l Ni sulphamate and NH, to give a p H of 6-8.

Electrolytic Cell Electrodes

NEW ZEALAND LTD. British Patent 959,498 Electrodes for brine electrolysis cells, etc., have T i electrodes whose anodic faces are coated with a Pt metal or its alloys.

Platinum Metal Hydrogenation Catalyst

Aminophenol is produced by passing a mixture of inert mineral acid, CH,COOH and HzO, containing IOU,', nitro-phenol, over a platinised or palladised charcoal catalyst.

Precious Metal Catalysts for Exhaust Puri- fiers OXY-CATALYST INC. British Patent 960,900 Pt, Pd, R u or Rh or their oxides are used in ex-

THE UNITED STATES TIME CORP.

IMPERIAL CHEMICAL INDUSTRIES LTD.

AUTOMATIC TELEPHONE 82 ELECTRIC CO. LTD.

IMPERIAL CHEMICAL INDUSTRIES OF AUSTRALIA &

ABBOTT LABORATORIES British Patent 959,507


haust gas purifiers supported on metal pellets. For example, 8-66 wt.':', of catalyst may operate at 5jo-7jo"F in a first chamber which is fre- quently replaced while the remainder of the catalyst operates at go0-135o"F in a second chamber which is rarely replaced.

Palladium-refractory Oxide-halogen Cata- lysts THE BRITISH PETROLEUM CO. LTD. British Patent 960,918 A catalyst suitable for the isomerisation of 4C and higher paraffins comprises a refractory oxide carrier, 0.01-5 wt.'!/, Pd and 1-15 wt.u(, C1, and is produced by impregnating the refractory oxide or its precursor with an ammoniacal solution of a Pd compound, precipitating the Pd, treating the composite product with hydrogen and contacting it with XYC12 where X and Y are the same or different H, halogen or SCl group and XY may be 0 or S .

Precious Metal Heat Detectors J. E. LINDBERG British Patent 961,143 Pd is used in a novel heat detector, suitable for detecting fire or indicating the prevailing temperature. See also No. 961,149.

New Platinum Complexes for Decorative Film Production

British Patent 961,315 Pt decorative coatings may be applied on refractory materials, leather, resins, laminates, paper, etc., by using chloroplatinous mercaptidethioether complexes and the usual fluxes and vehicles, For ceramic glazes the Pt complex may be combined with Au, Ag and Pd complexes.

Palladium-containing Catalysts for the Treatment of Exhaust Gases w. R. GRACE & co. British Patent 962,893 Catalysts suitable for the oxidation of exhaust gases of internal combustion engines consist of a high-surface area support, e.g. alumina, of 3-10 mesh carrying 2-20'3, CuO, 0.00254. I 04) Pd and I-IO?" Cr. They are prepared by impregnating the support with a solution of Pd salt and complex cuprous salt which is heated for 6-16 h at 100-15o"C, impregnated with a Cr solution and then calcined at 540-960°C for 2-5 h.

Improved Fuel Cells

British Patent 963,255 A fuel cell consists of Pt or Pd supported on Ni sintered C cathode and C supported Ag or Au anode prepared as described in British Patent No, 963,2 54 and separated by electrolyte. An aqueous H,O, solution is fed under slight pressure to the anode to act as oxidant and gaseous H, or N,H, or its salt solution is fed as fuel to the cathode.

ENGELHARD INDUSTRIES INC.

THE CHLORIDE ELECTRICAL STORAGE CO. LTD.

Palladous Chloride Catalyst for the Produc- tion of Unsaturated Esters

British Patent 964,001 Carboxylic acid esters of unsaturated alcohols are produced by contacting, at 50-180T, PdCle with an alpha-olefine under anhydrous conditions and in the presence of carboxylic acid carboxylate ions, 0, and a redox system comprising a salt of Cu and/or Fe.

Palladium Hydrogenation Catalyst METALLGESELLSCHAFT A. G. British Patent 964,152 Aromatic hydrocarbons are separated from hydrocarbon mixtures by hydrogenation over a zu/, Pd catalyst on a clay support followed by extraction with a mixture of pyrrolidine or its derivatives and H,O.

Platinum Hydrogenation Catalyst in the Preparation of Halogen Substituted Aroma- tic Amines E. I . DU PONT DE NEMOURS & CO. British Patent 964,166 Halogen substituted aromatic amines are produced by catalytic hydrogenation of halogen-substituted nitro-monocarbocyclic aromatic hydrocarbons at 30-15O0C, at least 7 atm. H, pressure and in the presence of I part Pt catalyst for every IO,OOO to IOO,OOO parts nitro compound and 0.01-1.0 mole cycloaliphatic nitrogen base per I mole nitro compound.

Precious Metals in the Separation and Purification of Hydrogen

British Patent 964,532 H, is separated or purified by contacting the gas mixture with a heated H,-permeable wall made from an alloy of 2-40 wt.% Ag or Au, 0.1-20 wt.3: Pt group metal and balance Pd.

Electrode for EIectrolytic Processes

British Patent 964,631 An electrode for electrolytic processes comprises Zr, Ta or Ti as the foundation metal and a surface layer of less than I p of a Pt group metal or metals, which surface layer also contains 0.1-0.7 wt.% C.

Use of Poisoned Palladium Catalysts in the Reduction of Gibberellic Acid and its Derivatives

British Patent 964,987 Gibberellin A and its derivatives are produced by the reduction with H, of gibberellic acid and its derivatives, this being done in ethyl acetate or tetrahydrofuran solvent containing 1-5 v01.q: tertiary organic base as catalyst poison, whilst 2-10~;; Pd supported on C, BaSO,, BaCO, or CaCO, is used as catalyst.


KABUSHIKI KAISHA YAMAMOTO KINZOKU KENKYUSHO

DEUTSCHE GOLD- UND SILBER-SCHEIDEANSTALT



Supported Palladium Hydrogenation Cata-

THE DOW CHEMICAL co. U.S. Patent 3,124,614 C-supported Pd catalysts containing 1-10 wt.:; metal are used to give 0.05-0.1 wt.?, of active metal in the hydrogenation of o-alkyl monohydric phenols with H,, at 100-300°C and 3 atm pressure, to the corresponding 2-alkyl cyclo- hexanones.

lyst

Desulphurisation Process for Hydrocarbons

U S . Patent 3,125,510 Hydrocarbon fractions with boiling points over 150°C are treated at 7oo-91o'F with Ha, and in the presence of 0.001-1.0 w t . O 0 halogen, over a catalyst comprising 0.01-5.0 wt."/o Pt or Pd on N,O, support to reduce their pour point by at least 5°F.

Ceramic Catalyst Flame Sprayed with a Platinum Group Metal

Inactive fired ceramic pellets containing at least So:/,> A1,0, are flame sprayed with a Pt metal to give a 0.0001 in. to 0.010 in. thick film. Such a catalyst remains active for a longer time and is less prone to poisoning.

Purification of Vinyl Chloride on a Platinum Metal Catalyst MONSANTO CHEMICAL co. US. Patent 3,125,608 Vinyl chloride is passed with H, over an inert support carrying 0.05-5.0 wt.?,, Pd or Pt at temperatures of 150-2oo0C which results in the removal of butadiene and formation of pure vinyl chioride.

Platinum Metal Butane Dehydrogenation Catalyst

Butane is dehydrogenated to butene by passing it at goo-1200°F over a calcined catalyst consisting of 75-99 wt."~,, A1,0, base, 0.01-5.0 wt.% Pt, Pd, Rh or I r or their mixtures and 1-20 wt.*/:) of an alkali metal having an atomic number of 3 to 5 5 .

Platinum Oxidation Catalyst

U.S. Patent 3,127,243 Potable water is recovered from human wastes by volatilising the volatile constituents, oxidising the contaminants present in the vapour by passing it over a Pt catalyst held at 400-1200°C together with air, and finally condensing the vapour.


NORTON CO. U.S. Patent 3,125,539

SINCLAIR RESEARCH INC. U.S. Patent 3,126,426

GENERAL ELECTRIC CO., NEW YORK

Platinum Metal Hydrogenation Catalysts

U.S. Patent 3,127,356 Hydrogenation catalysts of improved activity are obtained by depositing 0.5-2.0 wt.x Pt or Pd on

E. I. DU PONT DE NEMOURS & CO.

an inert support mixing it with 25 wt.%, based on dry weight of catalyst, of oleophilic C with at least 290 oil absorption factor, and subsequently reducing the deposited metal with H,.

Active Carbon-supported Palladium Catalyst

Alpha-methylstyrene is hydrogenated to cumene by passing it, together with elemental H, at 20-200°C and 1-10 atm. pressure through a catalyst bed consisting of 1-5 wt.'??; Pd/c.

SOCIETA ITALIANA RESINE U.S. Patent 3,127,452

Precious Metal Coated Anodes UNION CARBIDE CORP. U S . Patent 3,129,163 Anodes particularly suitable for electrolytic production of C1, are prepared by heat treating a T i alloy containing 4-30 wt.?, W at 1325-1950°F, shaping it, ageing at 1100-1300°F and subsequently plating it in a hot Pfanhauser bath with Ru, Rh, Pd, Os, Ir, Pt or Au to give a deposit of about 4 p in. thick.

Silver-Palladium Immersion Plating Com- position SEL-REX cow. U S . Patent 3,130,072 Ag is deposited chemically from aqueous solutions containing 0.5-30 g/1 alkali AgCN, up to 300 g/l alkali salt of a weak acid, up to 100 g/1 weak acid, 0.01-30 g/l palladous salt and sufficient NH, to give pH 8-10. The use of (NHa),Pd(NO,), and immersion temperatures of 50-100°C are preferred.

Dual-function Noble Metal Catalysts SOCONY MOBIL OIL co. U.S. Patent 3,130,147 An acidic catalytic composite based on Al-Zr-P, if combined with Pt or Pd, may be used for the desulphurization of hydrocarbon fractions under mild hydrogenating conditions.

Platinum Group Metal Catalyst in the Pro- duction of Aldehydes and Ketones CONSORTIUM FUR ELEKTROCHEMISCHE INDUSTRIE

Aldehydes and ketones may be produced from olefines by passing them and a mixture of 0, and water vapour at 0-300°C and 20 mrn Hg to 100 atm. over a catalyst comprising a Pt group metal salt and a transition metal salt in a I :I to I :20

ratio.

G.m.b.H. U.S. Patent 3,131,223

Platinum Group Metal Hydrocracking Cata- lysts UNION OIL COMPANY OF CALIFORNIA U.S. Patent 3,132,086 Hydrocracking of high boiling hydrocarbons is carried out in two stages; in the first, the feed- stock is conditioned to maximum catalyst efficiency and, in the second, subjected to hydrogenation at 400-72g"F and 500-3000 p.s.i.g. over a


0.05-1.50/b Pt, Pd, Rh or Ir catalyst. See also

Nickel and Rhodium Plating of Refractory Metals

U.S. Patent 3,132,928 Objects made of refractory metals are rendered resistant to corrosion and high temperatures by electroplating O.OOOI to 0.001 in. Ni followed by 0.0001 in. Rh and heat treatment at z500°F in a protective non-reactive environment.

Platinum Hydrogenation Catalysts HOFFMAN-LA ROCHE INC. U S . Patent 3,133,077 The reductive amination of an appropriate ketone using Hz and Pt group metal catalyst as the reducing agent produces 2-pyridyl-alkylamines which may be transformed to lower alkanoyl amides.

Platinum Hydrogenation Catalysts in the Production of Hydroxyl Ammonium Salts BADISCHE ANILIN-& SODA-FABRIK A.G. U.S. Patent 3,133,790 Hydroxyl ammonium salts are produced by the catalytic hydrogenation of NO in an aqueous solution of strong mineral acid containing a suspension of any convenient type of Pt catalyst. The catalyst may be used repeatedly, if, prior to passing of H, and NO, an inert gas is used to displace HJNO mixture and the solution i s gassed with NO before the production mixture is passed through it.

Stabilised Platinum Group Metal Hydrides

U.S. Patent 3,133,943 Stable organometallic hydrides suitable as oxidation, reduction, etc., catalysts are prepared by the reaction of a suitable ligand, a metal salt and H, in organic solvents and have general formula [X(DR2)ZrZlnE where E is Rh,HA or MHA; where M is a Pt group metal; A is H, halogen, alkyl, aryl or thiocyanate; X is alkylene or pheny- lene; D and Z are group VA elements, usually As or P; R is lower alkyl or aryl and n is 1-3.

Noble Metal Alloys Containing Gallium NOBILIUM PRODUCTS, INC. U.S. Patent 3,134,671 Alloys suitable for dentistry, jewellery, etc., contain in wt.O/,: 40-62 Pd, 40-10 Au, 2.0-5.0 Ru, 2.0-15 Ga and 10-25 of Cu or Ag or their mixtures.

Gaseous Fuel Batteries

A battery consists of two or more cells each of which has a hydrated ion exchange resin membrane which has integrally bonded Pt group metal, preferably Pt or Pd black, on opposite sides to form an anode and cathode, a supply of fuel gas to the anode compartment and of an oxidant gas to the cathode compartment and an electrically conduc-

3,132,087; 3,132,089; 3,132,090.

US, SECRETARY OF THE NAVY


GENERAL ELECTRIC GO. U.S. Patent 3,134,696


tive grid of Pt or Pd wire on which Pt or I'd black has been deposited which acts as a barrier between two adjoining cells and has projections connecting an anode of one cell with a cathode of another cell. See also 3,134,697.

Platinum Metal Catalysts for Gas-turbine Engines ROLLS-ROYCE LTD. U.S. Patent 3,136,125 An ignition device for gas turbine engines consists of a mass of refractory material which has a passage for the combustion-supporting gas/fuel mixture and this passage is lined with Pt, Rh or Pt-Rh and has also placed across it a flat piece and a wire helix made of the same catalytic material.

Noble Metal Alloys

U.S. Patent 3,136,634 Noble metal alloys of high specific electrical resistance, low temperature coefficient and low thermoelectric potential against Cu contain 18-75 wt.O/0 Au, 75-20 wt.l;a Pd, 2-15 wt.7" Fe and 0.4-5 wt."/, of Al, Ga, In or B.

Platinum Coated Refractories OWENS-ILLINOIS GLASS co. U.S. Patent 3,136,658 Refractories of alumina, zircon, mullite, etc., used as resistance elements and heaters, in particular in glass furnaces are protected by spraying them with molten Pt or with alloys containing 80 or more wt.2; Pt at a rate of at least IOO ft/sec.

Palladium Base Alloys J. B. COOPER & SONS INC. U.S. Patent 3,137,571 New alloys useful as electrical contacts and characterised by resilience, hardness and resistance to fatigue contain 0.5-15 wt.7, Ga, and, preferably 1-2 wt.'& Ga, and balance Pd.

Hydrogen Separation Membranes

Dutch Application 225,218 New device for the separation of hydrogen from gas mixtures uses a Group VIII metal, e.g. a Pd foil, supported by a sintered steel plate.

Mixed Metal Hydrogenation Catalyst

Dutch Applacation 230,040 A metal hydrogenation catalyst of a more selective nature is obtained by chemically depositing Cu on Pd particles which are optionally on a support.

DEUTSCHE GOLD- UND SILBER-SCHEIDEANSTAT

UNIVERSAL OIL PRODUCTS CO.

GENERAL ANILINE & FILM GORP.

Noble Metal Coatings on Titanium Electrodes

Dutch Application 235,848 T i electrodes are oxidised in some way to provide a surface oxide film and then coated with a porous layer of a noble metal, e.g. a Pt-Pd alloy

MAGNETO-CHEMIE N.V.

156

Titanium-Platinum Electrode

Dutch Application 247,771 A T i alloy electrode with improved polarisation properties consists of a Ti-Nb or Ta base coated wholly or partly with a Pt group metal or metals.

New Hydrogenation Catalyst

Dutch Application 247,951 A catalyst for the hydrogenation of acetylenic compounds to olefinic compounds is obtained by depositing a Pd salt on a support, reducing it to metal and treating it with stannous salt, e.g. SnCl,.

Selective Acetylene Hydrogenation Catalyst

Dutch Application 248,691 The catalyst is formed by depositing Pd in known manner on a support having an average pore diameter of at least roo and preferably 200-700 A.

Coating Titanium Electrodes

Dutch Application 250,923 T i or its alloys for use in electrodes are coated with a Pt metal by applying a suitable compound in organic medium, drying and heating above 500°C.

Platinum Metal Dehydrogenation Catalysts PROGIL s. A. French Patent 1,344,298 Higher phenols are prepared by the dehydrogenation of cycloaliphatic oxygenated compounds using a Pt group metal on a CaO, MgO, CnO, ZnO or kieselguhr support as catalyst. A fixed bed catalyst is used at 1-5 atm. and 200-350”c and an inert gas is passed through during the reaction.

Platinum Metal Catalysts in the Production of Alkylene- halohydrins FARBWERKE HOECHST A.G. French Patent 1,344,652 Alkylene-halohydrins are produced by reacting olefines and oxygen at 0-25°C in an aqueous solution containing a Pt or Pd salt as catalyst, a Cu or Fe salt as a redox system and also with appropriate halogen ions present.

Selective Organic Hydroperoxide Hydrogena- tion Catalyst

French Patent 1,345,953 Hydroperoxides are selectively hydrogenated in admixture with other hydrocarbons and in particular with methylpentenes, over a Pt metal catalyst which has been poisoned with 100-300 wt.y(, of a metal from groups IB, IIB, IIIB or IVB; the use of CaCO, as poison is quoted.

Finely Divided Platinum Metal Catalysts

French Patent 1,346,159 Catalytic Pt, Pd, R h and Ru of extreme activity


STE. USINHS CHIMIQUES RHONE-POULENC




H. C. BROWN, C. A. BROWN


and in a finely divided state, particularly suitable for hydrogenation or reduction reactions, are obtained by immersing a support of high specific area in a solution of appropriate Pt metal to which has been added an alkali or alkaline earth metal borohydride.

Noble Metal Alloys of High SpecXc Electrical Resistance

French Patent 1,346,215 Alloys comprising 18-757; Au, 75-20% Pd, 2-1574 Fe and 0.4-5% Al, B, Ga or In (with the content of these latter metals being at least 504 less than the Pd content) are characterised by high specific electrical resistance.

Palladium Organie Acetates

French Patent 1,346,219 A catalyst comprising about 2.0 wt.4: Pd on an inert support with a specific area of less than 50 m2/g is used in the production of organic acetates by the reaction of alkyl benzenes, O2 and CH,COOH at 50-250”C and 2-200 atm.

Platinum-plated Forehearth or Dipping Plunger CORNING GLASS WORKS French Patent 1,346,922 A plunger suitable for use with melted glass at 1300-1600’C, has a Mo core containing less than o.or?/,C and a 30-100 mil thick plating of Pt or 7:3 Pt:Rh alloy.

Platinum and Palladium Oxidation Catalyst w. R. GRACE & co. French Patent 1,347,318 An inert inorganic support of 10-100 microns particle size, e.g. SiO,-A1,0,, carrying 0.5-10 wt.7; Pt and Pd in a 0.125-2.0 wt. ratio is diluted with 5-250 wt.04 of a fine inorganic compound to give 0.005-0.~ wt.% of each metal and, after activation by calcining, is used as an oxidising catalyst for combustion engine exhaust gases to eliminate air pollution.

Precious Metal Coated Titanium Electrode CANADIAN INDUSTRIES LTD. French Patent 1,347,529 An anode for the electrolysis of brine has a central T i core and a 0.254 to 5.08 micron thick electro- lytically deposited film of Pt alloy containing 35- 60 wt.”A, Rh, preferably about 50 wt.% Rh.

Cracking Catalyst THE BRITISH PETROLEUM CO. LTD. French Patent 1,347,559 A catalyst for the cracking of hydrocarbons at 400-~50°C for 10 mins.-24 hrs. consists of an inert support containing at least 50 wt.76 A1,0, and 0.01-5 wt.% Pt metal, preferably Pt, 1-2.5 wt.% halogen and 0.20-0.40 wt.”/o H,.

DEUTSCHE GOLD- UXD SILBER-SCHEXDEANSTALT

Catalyst for the Production of

FARBENFABRIKEN BAYER A.G.

157

Platinum Metal Dealkylation Catalyst

French Patent 1,347,632 Alkyl-substituted aromatic hydrocarbons are dealkylated by using Al,O, impregnated with 0.1-2.0 wt.% Pt metal, 3-10 wt,yo fluoride as catalyst and by passing H, through with a gas mixture held at 4oo-500°C and 14-17 kg/cm2.


Platinum Group Metal Catalysts INSTITUT FRANCAIS DU PETROLE, DES CARBURANTS ET LUBRIFIANTS French Patent 1,349,145 Heavy petroleum fractions and naphthas may be converted to 3-5C hydrocarbons by treating them with H, at 375-45o"C and 30-150 atm. in the presence of an alumina support carrying 0.05-5.0 wt.O,, Pt, Pd or Rh,o.I-Io wt.',; F2 and 0.02-3.0 wt."; B. See also 1,349,146; 1,349,147.

Palladium Catalysts for the Hydrogenation of Benzoic Acid SNIA VISCOSA S.P.A. French Patent 1,349,763 A hydrogenation catalyst is prepared by treating C with a solution of Pd salt containing a theoretical excess of alkali metal hydroxide, followed by reduction of Pd metal with HCHO at 50-100°C.

Hydrogenation of Unsaturated Aldehydes to Alkanols THE DISTILLERS co. LTD. French Patent 1,349,816 An unsaturated aldehyde is reacted in the vapour phase with H, in the presence of a Kieselguhr- supported catalyst containing 25-90 wt.?; Cu and the vapours are then reacted further with H2 in the presence of a carbon supported catalyst containing 0.1-10.0 wt.?; Pd to yield the appropriate alkanol.

Platinum Group Metals in Coating Graphite with Refractories SOCIETE NATIONALE D'ETUDE ET DE CONSTRUCTION DE MOTEURS D'AVIATION French Patent 1,350,772 Graphite and similar materials may be made to withstand high temperatures by coating with a refractory material containing 1-50 wt.?$ Pt group metal and then applying a thicker coating of Ta, Hf, Mo, Nb, Ti or W or their carbides, nitrides or borides. The use of an intermediate film of Pt metal alloy improves the adhesion between the graphite and the refractory material.

Platinum Group Metal Hydrocarbon Conver- sion Catalysts

French Patent 1,350,947 A catalyst suitable for hydrocarbon conversion reactions, e.g. hydrogenation, cyclisation, etc., consists of an inert support carrying 0.05-5 wt.9; Pt group metal and 0.1-40 wt.qh rare earth oxide in a relative metal ratio of 0.1-0.9.

SOCONY MOBIL OIL CO. INC.

Brazing of Metals

French Patent 1,351,406 Metals or alloys which contain components volatile at high temperatures are brazed advantageously in an atmosphere of H,, N, or cracked NH,, after they have first been coated with Rh.

Use of Palladium-nickel Alloys in High Temperature Brazing

French Patent 1,352,021 High temperature brazing resistant to oxidation is obtained by using brazing alloys Containing, in wt.yo, 30-35 Cr, 16-19 Pd, 4-6 Si, 1.1-3 T i and 1-2.5 Al, the rest being Ni and impurities.

Palladium and its Alloys in the Separation of Hydrogen from Gaseous Mixtures

French Patent 1,352,751 The construction of hydrogen diffusion tubes made of Pd or 2 5 O ( , Ag-Pd alloy is improved and the service life is prolonged by incorporating in it a steel or Ni alloy strengthening spiral.

Palladium Chloride in the Oxidation Catalyst System

French Patent 1,353,157 Olefinic hydrocarbons are oxidised in the course of the production of glycol diesters at 0.1-10 atm. and 50-16o~C using a catalyst comprising PdCl,, an ionised carboyxlate, carboxylic acid and a convenient redox system.

Direct Conversion of Thermal Energy to Electrical Energy

German Patent 1,166,306 Thermionic converter using an emitter electrode or carrier plate encloses the electrode in a housing permeable to H, at high temperature, e.g. Pt or Pd.

Activated Platinised Titanium Anode

German Patent 1,170,378 Electrodes for alkali chloride electrolysis are produced by coating a T i part with amorphous Pt and then activating by heating the coating to a temperature above 316°C in the presence of an air stream containing a hydrocarbon vapour.

Removal of Acetylenes and Dienes from Hydrocarbons

German Patent 1,171,901 Small amounts of acetylenes and dienes are removed from mono-olefines by selective hydrogenation over a I'd catalyst supported on Al,O, with a pore size of not more than 0.4 cc/g, a pore diameter of less than 800 a and 0.01-0.09 wt. Pd.

CIE. FRANCAISE THOMSON-HOUSTON

UNITED STATES ATOMIC ENERGY COMMISSION

JOHNSON, MATTHEY & CO. LTD.


SIEMENS-SCHUCKERTWERKE A.G.

UNIVERSAL OIL PRODUCTS CO.

GIRDI-ER-SUDCHEMIE KATALYSATOR G.m.b.H.


AUTHOR INDEX TO VOLUME 8

Page Adamec, J. B. 33 Adamenkova, M. D. 34 Akerman, K. 127 Alchudzhan, A. A.

112, 113 Ali, S. I. 113 Alybina, A. Yu. 11 1 Andersen, C. A. 30 Anderson, C. J. 108 Anderson, E. 70 Angelici, R. J. 72 Angus, H. C. 147 Aronsson, B. 72

Bagotzky, V. S. 33 Bakhmet’eva, G. S. 150 Balandin, A. A.

36, 76, 112 Balenkova, E. S. 11 1 Banks, W. P. 37 Banta, M. C. 73 Barbur, I. 74 Barde, R. 76 Baron, V. V. 31 Bartlett, N. 31, 108 Batashev, K. P. 73 Bath, S. S. 72 Beeskow, H. 29, 30 Bell, W. E. 72

Bender, D. 71 Berkowitz, A. E. 107 Bertodo, R. 128 Bianchi, G. 152 Bjornstjerna, V. 70 Blackburn, G. F. 114

Block, F. E. 70 Bockris, J. O’M. 149

Bond, G. C. 92 Bragiu, 0. V. 36 Brailovskii, S . M. 11 3 Breiter, M. W. 73, 109 Brophy, J. H. 71, 107

Bucher, E. 71, 148 Burke, L. D. 149

Busson, N. 76 Bnvet, R. 76

Bel’skii, I. F. 34

Bloch, H. S. 2

B#di, A. 74

Brundige, E. L. 33

Bnrwell, R. L. 75

Caldwell, F. R. 114 Calvert, L. D. 108 Campbell, J. S. 15 Camera, N. J. 148 Carrington, A. 31

Carter, J. L. Chalk, A. J. Chanley, J. D. Chaston, J. C. Chatt, J. Chernyaev, I. I. Chiswell, B. Chodosh, S. M. Chultem, D. Clement, W. H. Coffre, R. Coker, W. P. Cole, W. Coles, B. R. Colman, W. P. Colombani, A. Crahol, J. Cronin, P. A. Cross, A. S. Cunningham, D. A.

Page 149 151 111 50 72

109 72 36

151 I12 152 113 34 9

36 146 146 31 33

110

Dahms, H. 149 Damjanovic, A. 109 Darling, A. S. 134 Dantova, L. I. 29 Davies, N. R. 75, 112

Demchenko, V. V. 32 Dickinson, J. M. 148 Dietz, H. 32 Dobroserdova, N. D.

35, 150

Drautman, J. J. 108

Davis, Q. V. 15

Dozono, T. 35

Duwez, P. 108

Edshammer. L.-E. 70 Elagina, N. V.

75, 150, 151 Emel’yanova, G. I. 112 Endter, F. 110

Falbe, J. 151

Ferretti, A. 110

Falkenburg, G. 101, 133 Fenerty, J. 98

Feuillade, G. 77,114,152 Firnhaber, B. 152 Fischer, E. 0. 32, 72 Flanagan, T. B. 147 Fletcher, D. N. 12 Fletcher, J. M. 32 Fogel’, Ya. M. 111 Ford, L. A. 82 Franklin, T. C. 75 Freidlin, L. Kh. 34, 151 Furst, H. 74

I Galagali, R. J. Gardner, W. E. Garnett, J. L. Geary, A. L. Gerasimov, Ya. I. Cerischer, H. Giessen, B. C. Gilman, S . Coetz, W. K. Gijhr, H. Goneim, F. B. Gonikberg, M. G. Gostunskaya, 1. V.

Grant, N. J. Greene, N. D. Greenfield, H. Griffin, 0. G. Grigor’ev, A. T. Grishina, T. M. Crubb, W. T. 36, 76, Gryaznov, V. M. Gschneidner, K.-A. Gutt, W. Guyer, P.

Haake, P. Hackerman, N. Haensel, V. Hagmann, D. Haldeman, R. G. 36, Hall, W. K. 30, Ham, G. E. Hanks, G. S. Harrod, J. F. Hartner, A. J. Hayter, R. G. 72, Headley, J. A. Heiniger, P. Held, J. Heyne, W. Hieber, H. Hill, J. Ho Chin-Fyn Hoar. T. P.

35, 150,

Hoare, J. P. 33, 90, 109,

Hoffman, L. C. Hoffman, P. M. Holloway, J. H. Holt, E. Holtzherg, F. Honeywell, W. I. Huch, R. Huff, J. Hull, G. W. Hulliger, F. Hunt, H. R.

=age 107 32

111 31 70 77

148 32

107 32 76 74

151 148 76 35

115 70 35

114 34 30

153 151

31 73 2

29 73

111 113 33

151 36

109 33

148 77

I45 102 55

150 14

I10 22

127 32

140 107 115 147 152 108 71 32

Page Hunt, L. B. 23 Hunter, J. B. 29 Huntsman, W. D. 11 3 Hutchinson, J. H. 72

Ibach, H. 148 Ismail. S. M. 151

Jackson, G. D. F. Jacobus, G. F. Jaqnin, M. Jaffee, R. 1. Jasinski, R. Jeantet, R. Jcssen, K. Jcwell, R. C. Johnson, J. W. Johnson, S. A. Jorge, L.

76 73 76 31

152 148 29

122 149 32

33,73

Kaup, Yu. Yu. Kazanskii, B. A. Keen, I. M. Kemball, C. 75, 112, Kevorkian, V. Khitrov, A. P. Khomchenko, L. P. Khoobiar, S. Khromov, S. I. Kiji, J. 1

Kistuer, C. R. Klement, W. Klemm, W. Klyshin, V. V. Knapton, A. G. Knobler, C. M. Kobayashi, T. Kobozev, N. I. Koda, Y. Kolbel, H. Kolbin, N. I. Kornilov, I. I. Korte, F. Koster, W. Kozik, B. L. Kozusnik, Z. Krier, C. A. Kubokawa, Y. Kuunmann, W. Kurath, P. Kussman, A. Kuz’min, R. N.

34 35

143 149 111 150 35

110 151 75 72 70

147 71

148 115 29 34 72

152 72 71

151 29 76 77 31

150 110 34 29 30

Langer, S. H. 73, 109 La Pluye, C. 75 Lebedev, V. P. 112


Page Page Page Page Lederer, L. 76 Mosevich, I. A. 75 Rhys, D. W. 110, 130 Temkii, 0. N. 113 Leonova, A. I. 35, 151 Muller, W. H. E. 152 Rice, F. J. 113 Thornasson, C. V. 110 Lever, F. M. 106 Myasnikova, K. P. 71 Riesz. C. H. 152 Thomson, J. R. 71, 107 Levitskii, I. I. 74 Lewis, B. 147 Lewis, F. A. 149 Libeman, A. I,. 36 Litvin, E. F. 34, 151 Lin, C. F. 32 Liu, C. H. 32 Li Ven’-Chzhou 11 2 Livingstone, S. E. 72

Loebich, 0. 148 Lohmann, D. H. 108 Lucchesi, P. J.

74, 111, 149 Luo, H.-L. 70, 108 Lutinski, F. E. 111

Llopis, J. 33, 73

McClelland, D. C. 75 McDonald, D. 67 McGeagh, J. 33 McKee, D. W. 113 Mackliet, C. A. 107 Madden, R. P. 73 Madison, N. L. 113 Maeland, A. 147

Manly, D. G. 113 Mantikyan, M. A.

112, 113 Margraje, J. L. 30 Markovic, T. 32 Masumoto, H. 29 Matlack, G. L. I14 Maurer, R. 150 Maxted, E. B. 113, 151 Mayell, J. S. 109 Mazitov, Yu. A. 109

Merz, H. J. 151

Mdl’tSCV, A. N. I12

Mcnting, L. C. 1 08

Meyer, E. F. 75 Meazetti, T. 111 Michaelske, C. J.

76, 114 Michalik, S. J. 71

Minzl, E. 147 Mirzaeva, A. K.

75, 150, 151 Moiseev, I. 1. 35 Mordike, B. L. 102

Miller, M. C. 110

Nachtrieb, N. €I. Nadykto, B. T. Naito, T. Nakata, H. Niedrach, L. W. Nikifornva, A. V. Norman, J. H. Norton, F. J. Novak, B. Nuszberger, J.

Oldfield, L. F. Olsen, L. 0. Oswin, H. G.

Palmer, N. I. Paris, B. Patterson, W. R. Paule, R. C. Peacock, R. D. Pells, G. P. Peplow, DL B. Pestrikov, S. V. Phillips, J. H.

70 111 152 76 36 35

109 113 32 37

107 114

36,42

36 149 112 30 32

147 114 76

11-8 I 4 1

Phil& W. L. 107, 148 Pichler, €I. 152 Plate, A. F. 151 Polkovnikov, B. D.

36, 112 Poltorak, 0. M. 34 Polyakova, V. P.

71, 107 Powell, R. W. 13 Pozharskaya, G. V. 70 Presnyakov, A. A. 29 Price, E. G. 130 Prigent, M. 152

Rao, M. L. B. 109 Rapperport, E. J.

31, 148 Raub, C. J. 30, 31, 108 Raub, E.

29, 30, 101, 133, 148 RQdr, M. 77 Reid, F. H. 73 Reinacher, G.

33, 74, 149 Reiswig, R. D. 30, 148

Roberts, R. W. 31 Rooksby, H. P. 147 Ronney, J. J. 149 Raschel, E. 30, 148 Rosen’tdl, K. I. 109 Rowland, R. L, 70 Ruh, E. 74

Saini, G. S. 108 Sasse, W. H. F. 76 Savitskii, E. M. 31 Scagnetti, M. 146 Scharkow, V. I. 36 Schindler, A. 1. 107 Schmahl, N. G. 147 Scholtus, N. A. 30 Schone, S. 114 Schuldiner, S. 149 Scott, R. J. 74 Selwitz, C. M. 112 Semenov, 1. N. 72 Shekhobalova, V. I. 34 Shephard, F. E. 149 Shiba, T. 35 Shmonina, V. P. 150 Shreir, L. L. 114 Shuikin. N. I. 34 Sinfelt, J. H.

74,110,111 Skatulla, W. Slack, G. A. Slobodin, Ya. M. Smidt, J. Smith, C. E. Smith, M. F. Sollich, W. A. Staley, H. C. Stringfield, C. M. Strugaru, D. Sudbury, J. D. Sundaresen, M. Symons, M. C. R.

114 107 150 35 98

148 111 109 115 74 37 70 31

Taber, A. M. 36, 112 Tagami, M. 72 Tainsh, R. J. 1 08 Takagi, Y. 35, 152 Takashima, S. 150

Tlamsa, J. Toda, G. Toya, T. Traini, C. Trent, D. E. Tsarev, B. M. Tsishevskii, R. Tsuchida, T. Tsuji, J. Tsyganova, I. A. Tverdovskii, I. P. Tye, R. P. Tylkina, M. A.

29,

37 70 29

152 149 114 71 30 75 29 75 13

71, 107

Ursu, I. 74

Van Kuijk, J. C. M. 108 Van Laar, B. 147 Vaska, L. 72, 108 Vautier, C. I46 Vogler, A. 32 Vybihal, J. 111

Walker, R. F. Walter, P. H. L. Warner, T. B. Webb, G. Weber, H. S. Weidenbach, G. Wenzel, M. White, G. K. White, L. J. Wicks, C. E. Wilkinson, G. Woolley, J. C. Wroblowa, H.

148 1 08 149 60

152 74

150 1 08 12 70 16

147 149

Yagodovskii, V. D. 34 Young, J. R. 33

Zachariasen, W. H. 31 Zhadan, A. I. 114 Zheligovskaya, N. N.

109 Zhuravlev, N. N. 30 Zwingmann, G. 147


SUBJECT INDEX TO VOLUME 8 a-abstract Anodic Protection, of carbon steel, a

Page 37

Brazing, Pd in ceramic-to-metal seals, a Brazing Alloys, containing Pd, a

33 33

Calorimeter, differential, high temperature, a 1 10 Catalysis, Third International Congress 131 Catalysts,

Adams’, hydrogenation of dihydrolanosteryl and dihydroagnosteryl acetates, a 111

IrCl,, isomerisation of olefins, a 151 Ir/C, hydrogenolysis of

1,2-dimethylcyclopentanes, a 36 Os/Al,O,, hydrogenation and deuteration 60 Os/C, Hydrogenolysis of

1,2-dimethylcyclopentanes, a 36 Palladium, black, decomposition of 0,, a 112

black, effect of ultrasonics, a 112 black, hydrogenation of dienes, a 151 black, hydrogenation of pentynes, a 34 black, hydrogenation of piperylene

Isomers, a 34 black, isomerisation of hexenes, a 35 conversion of methylpentenes, a 151 films, fission of C-halogen bond, a 75 films, oxidation of olefins, a I12 Raney-type, promotion by B, a 112

PdCly, activation, a 151 formation of ethyl-3-butcnoate, n 75 formation of methyl ethyl ketone, a 76 interaction with C2Ha, a 1 1 3 isomerisation of olefins, a 75 oxidation of alcohols, a 35

112 oxidation of olefins, a 35 oxidation of propylene, a 35

75 Pd/Al.O,, deactivation, u 113

deutcration of butyne and butadienes, a 75 deuteration of dialkylacetylenes, a 15 hydrogenation of furans, a 34

PdJC, formation of 2,2’-bipyridyl 76 hydrogenation of aryl nitro groups,

inhibitors, a 35 hydrogenation of furans, a 34 hydrogenation of nitrocyclohexane, a 151 hydrogenation of olefins, n 113 hydrogenolysis of

1,2-dimethyIcyclopentancs, a 36

isomerisation of olefins, a 151 Pd/oxide supports, for hydrogenation, a 113 Pd/SiO*, dehydrogenation of cyclohexane, a 112

Palladium-Rhodium, activitv, a 113 Pd-Ag/SiO %, dehydrogenation of

cyclohexane, a 113 Platinum, a$orption of H2,, a 75

112 150 112 34

black, hydrogenation of pentynes, a 34 black, hydrogenation of piperylene

Isomers, a 34 black, reduction of nitrobenzene, a J 50 conversion of methylpentenes, a 151 decomposition of NH,, a 1 1 1 duofunctional, in petroleum refining 2 films, dehydration of cyclohexadiene-1.3 34 films, fission of C-halogen bond, a 75 films, oxidation of olefins, a 112 isomerisation of hexenes, a 150 Raney-type, promotion by B, a I12 synthesis of HCN, a 110

PdCI&uCl,, conversion of a-olefins, n

Pd-Au, hydrogenation of quinone, a

isomerisation of hcxenes, a 35

Palladium-Platinum, activity, a 113

aromatisation of gasoline, a 111 black, activity, a 75 black, decomposition of 0,, a black, desorption of Hi! a black, effect of ultrasonics, a black, hydrogenation of diencs, n

Catalysts (contd.) Platinum Metals, activation energy, a

borides of, a complexes, isomerisation of olefins, a hydrogenation of soybean oil, a olefin complexes reacted with NaBH,, a

Pt/Al ,03, active surfaces, a chemisorption of C2Ha, a conversion of

desorption of Hp, a effect of HIO, a HE-D, exchange, a hydrogenolysis of cyclopentanes, n hydrogenolysis of C,H,, a migration of H atoms, a reactions of C, aromatics, a

PtjC, conversion of n-amylbenzene, a conversion of

conversion of spiro-(S,6)-dodecane, n conversion of spiro-(5,5)-undecane, a E.S.R. studies, a E.S.R. studies in gases, cz hydrogenation of cyclododecane, IJ hydrogenation of furans, a hydrogenation of nitrocyclohexane, a hydrogenation of vinylcyclohexanc, a isomerisation of hexenes, a isomerisation of olefins, a oxidation of H?, a tritiation, a

Pt/oxide supports, properties, a Pt/SiO,, desorption of H *+ o

hydrogenation of C,H,, a hydrogenolysis of cyclopentanes, a hydrogenolysis of C2€i6, a mixed with Also,, a oxidation of NH,, a preparation and properties, a

PtjSi0,-Al,O, conversion of

Ptizeolite, hydrogenation of butenes, a P t 0 2 , hydrogenation of dihydrolanostcryl

hydrogenation of dimethylcyclobutane hydrogenation of organic acids, a self-activation for D, exchange, a

Platinum-Palladium, activity, a Platinum-Ruthenium, CH,-D, cxchange, a Rhodium, black, hydrogenation of olefins, a

black, hydrogenation of pentynes, a reduction of organic compounds, a

RhCl,, isomerisation of olefins, a Rh/A120a, hydrogenation of haloalkenes, a Rh/C, formation of 2,2’-biquinolyl, a

1,2-dimethylcyclopentanes, a Rhodium-Palladium, activity, a Ruthenium, hydrogenation of organic

synthesis of paraffin waxes, a Ru/AIBOB, hydrogenation and deuteration Ru/Ba SO,, production of polyhydroxy

R U G hvdrogenation of organic

1,l-dimethylcyclohexane, a

I , I -dimethylcyclohexane, n

cyclopentanes, a

and dihydroagnosteryl acetates, a

hydrogenolysis of

compounds, a

alcohols, a

compoun&, a I

production of polyhydroxy alcohols, a Ru/SiO,, hydrogenolysis of GH,, a RuO,, hydrogcnation of aromatics, a

compoun&, a I

production of polyhydroxy alcohols, a Ru/SiO,, hydrogenolysis of GH,, a RuO,, hydrogcnation of aromatics, a

synthesis of polymethylene, a RuOl, oxidation of steroid alcohols, a Ruthenium-Platinum, CH,-D, exchange, a Sodium Chloropalladate (11), isomerisation

2athodic Protection, PbjPt anodes, a :ornosion, Ir, a 3

of olefins, a

Page 32 36

151 152 92 36 74

149

151 150 74 . .

111 150 111 110 149 151

151 150 75 74 74

111 34

1 5 1 151 150 151

74 150 1 1 1 150 110 150 11 1 74 34 34

1 so 110

111 , , a150

34 111 113 113 151 34 35

151 113 76

36 I13

35 152 60

36

3.5 36 76

152 152 76

I13

112 114

‘3, 73


Page

110 110

Crucibles, Pt, calorimeter, a 110

Crystal Growing, Pt in cell for, a Pt metals, polymerisations in, a

Deuterium, absorption in Pt-Pd alloys, a 147 74, 111, 113

Diffusion Cells, for H z purification, a 29, 33, 91, 114

exchange reactions, a Dew Point Meter, a 115

Electrical Contacts, Pd, effect of organic vapours, a 37

Electrodeposition of,

Electrodes,

Pt metals, Graz symposium 99

Platinum Metals, applications, 4 73 Rhodium, stress and contamination 55

activated graphite discs, a 152 screens, Pt and Pt-C, a 36 Iridium, anodes, oxidation of CeH4, a 149

cathode base, a 114 Pb/Pt, anodes, for marine cathodic

protection, a 114 Noble Metals, potentials in metal-0,-acid

systems, a 1 09 potentials, a 109

Palladium, anodes, oxidation of C2H4, a 149 black 90 in fuel cells, a 76 oxidation, a 109 palladised, hydrogenation of C2H,

and C2Hl, a 149 Palladium Alloys, anodes, in fuel cells, a 36 Pd/Ni, in fuel cell, a 152 Pdjstainless steel, in hydrogen Purification, a 73 Palbddium-Silver, in fuel cells, a 76 Platinised Ti, anodes, in electrorefining

of c o , a 73 Platinum, anodes, cleanliness, a 149

anodes, oxidation of C2H3, a 149 anodes, oxidation of organic

anodes, protection of carbon steel, a 37 black 90 black, in fuel cells, a 36, 114, 152 cell for O2 determination, a 1 I 0 chemisorption of O1 and Ha, a 32 effcct of acidity, a 73 for resistivity measurements 98 in cell for crystal growing, a 110 in fuel cells, a 36, 76, 114 oxidation, a 32, 109 oxidation of CO and CH,OH, a 32 platinised gauze, oxidation of CeH2, a 149 platinised, hydrogenation of CHp and

cay,, a 149 reduction of Op, a 109

32 a.c. polarisation 90 in electrochemistrv 14

compounds, g 33

Platinum Metals, activation energy, a

in fuel cells 42, oxidation and adsorption of CH,OH, a

Pt/Ni, in fuel cells, a Pt/stainless steel, in hydrogen purification, a Pt/Ta, in hydrogen purification, a

in fuel cells, a P t or Pd, in fuel cells, a Rhodium, anodes, oxidation of CaHI, a

in hydrogen purification, a oxidation, a reduction of organic compounds, a

Electron Probe Scanning Microanalyser Electronics, Pt wave-guide termination Electron Microscope, Pt in heating stages, a

Filters, sintered Pt Fuel Cells, electrode structure, a

hydrocarbon/air, a Hz-CLa, u

1 i4 73

152 73 73

152 77

149 73

110 35

122 15 33

54 152 36

152

Fuel cells (conrd.) Page CH,-02, with Pt electrodes, a 76

oxidation of CHrOH, a 152 Pd alloy anode, a 36 Pd and Ag-Pd electrodes, a 76 Pd H,-diffusion electrode, a 76

Pt black electrodes, a 114 Pt metals in 42 Pt or Pd black, a 71 CsHa-On, a 114 saturated hydrocarbon, a 36 thin electrodes, a 36 types of electrodes, a 114

Furnace, for microscopy and X-ray analysis, a 153 high temperature, Rh-Pt wound 66 Pt-lined, for fluorination of U compounds 12 resistivity of refractories for 98 Rh-Pt wound, in X-ray diffractometer, a 74

oxidation of hydrocarbons, a 152

physical chemistry, a 77

Glass, kinematic viscosity, a 114

Hydrogen Cyanide, synthesis, n 110 Hydrogen Diffusion, in Pd and

Pd alloys, a Hydrogen Purification, tubes for

Hydrogenation of,

70, 76, 114 33, 91

electrolytic technique, a 73

C ~ H I , a 149 acetylenes and C2H, 60 aromatics, a 152 aryl nitro groups, a 35 butenes, a 110 cyclododecane, a I l l dienes, a 34, 151 dihydrolanosteryl and dihydroagnosteryl

acetates, a 1 1 1 dimethylenecyclobutane, a 1 50 CnHw a 76 ethyl crotonate, a 151 CZH4, a 110, 149 haloalkenes, a 113 hexenes, a 35 Z-methyl-5-acetylfurans, (I 34 nitrocyclohexene, a 151 olefins, a 113, 151 organic acids, a 34 organic compounds, a 35 pentynes, a 34 piperylene isomers, a 34 quinone, a 15 soybean oil, a 152 vinylcyclohexane, a 151

Iridium, adsor tion and decomposition of

corrosion 33, 130 crucibles, a 110, 149 crystals, deformation of 102 Irl*r isotope in HNO, manufacture 127 oxidation, a 107 passivation, a 73 valve cathodes, a 114 vapour pressure 30, 134

with rcfractory metals, a 31 Iridium-Boron, crystal structure, a 72 Iridium-Iron, structure, a 148 Iridium-Molybdenum, a 71 Iridium-Niobium, crystal data, a 148

superconducting phase, a 148 Iridium-Osmium, phase diagram, a 148 Iridium-Palladium, constitution, a 148 Iridium-Platinum, crucibles, a 74

114 Iridium-Ruthenium, phase diagram, a 148

hy8ocarbons on, a 31

Iridium Alloys,

viscosity of glass apparatus, a


Iridium Alloys (contd.) Iridium-Tantalum, crystal data, a Iridm-Thorium, constitution, a Iridium-Titanium, superconductivity, a Iridium-Tungsten, constitution, a

Iridium-Zirconium, superconductivity, a Iridium Complexes, structure, a

with phenanthroline, a

superconducting phase, a

Klaus, research by

Magnets, Pt alloy, circuit design for, Co-Pt, by powder metallurgy, a

Nitric Acid, manufacture, Irlsr in

Organometallic Compounds, of Pt metals Osmium,

carbides not formed, a oxidation, a semiconductors with As, P, S, Sb, Se, Te. vapour pressure I

Osmium-Boron, crystal structure, a Osmium-Iridium, phase diagram, a Osmium-Molybdenum. superconducting

Osmium Alloys, with refractory metals, a

Page 148 71

108 71

148 108 72 72

67

82 147

127

16

, a 34,

. . phase, a

Osmium-Nickel, mechanical properties, a Osmium-Niobium, superconducting phase, a Osmium-Thorium, constitution, a

Osmium Chloride Complexes, structure, a Osmium Complexes, hahdo- and hydrido-alkyl

and -awl, a Oxidation of,

CtHz, a alcohols, a NH,. a butylenes, a CO and CH.OH, a

hvdrocarbons. a CzHI, a

Hm a CHI, a CHIOH, a olefins, a organic compounds, a Pt Pt metals, a propylene, a steroid alcohols, a

Oxygen, determination in gases, a

73, 35,

148 107 71

148 31 72

148

148 148 148 71 72

72

149 35 34 76 32

149 152 74 76

152 112 33 50 31 35 76

110

Palladium, black, formation 90 crucibles for polymerisations, a 110 diffusion of H Z in, a 33, 70 for brazing, a 33 in precision glaze resistors 22 oxidation, a 107 vapour pressure 134

29 in fuel cells, a 36 Palladium-Aluminium, crystal structure, a 70

superconductivity, a 31 Palladium-Cadmium, magnetic

susceptibility, a 29 Palladium-Cobalt-Manganese, melting

Palladium-Copper, solid solutions, a 29 Palladium-DvsDrosium. magnetic

Palladium Alloys, hydrogen diffusion, a

Palladium-Arsenic, constitution, a 108

equilibrium, a I47

~- properties,- a 107

9. 107 Palladium-Gadolinium, magnetic properties, a

Palladium-Holmium, magnetic properties, a ' 107 Palladium-Hydrogen, hysteresis, a 30 Palladium-Indium, magnetic susceptibility, a 29

Palladium Alloys (contd.) Page Palladium-Iridium, constitution, a 148

phase diagramEJow,950"C, a 29 transformation kinetics, a 29

Palladium-Iron-Copper, properties, a 70 Palladium-Maneanese. crystal and maenetic

Palladium-Iron, ma etic properties 9

- . - I

structure, a 71 Palladium-Molybdenum, constitution, a 70 Palladium-Nickel. heat caeacitv. a 107 _.

mechanical properti&, a 148 structure, a 71

148 Palladium-Niobium, crystal data, a superconducting phase, a 148

Palladium-Phosphorous, superconductivity, a 3 1 Palladium-Platinum, absorption of

H,andDp,a 147 Palladium-Rhenium, properties, a 29 Palladium-Rhenium-Tungsten, structure, a 107 Palladium-Rhodium, effect of Rh,Os, a 147

magnetic susceptibihty, a 147 Palladium-Ruthenium. magnetic


. - susceptibility, a

Palladium-Silver, diffusion tubes, a 33, hydrogen content, a self-diffusion of Pd in, a

Palladium-Tantalum, crystal data, a Palladium-Terbium, magnetic. properties, a Palladium-Thorium, constitution, a Palladium-Tungsten, constitution, a Palladium-Tungsten-Rheniuq structure, a Palladium-Uranium, phase diagram, a

Palladium Complexes, a 32, Palladium Oxides, properties, a Petroleum Relining, aromatisation of gasoline, a

duofunctional Pt catalysts Platinax 11, circuit design Platinum, activated surfaces

adsorption of halide ions, a adsorption of H , a black, formation contamination, in glass industry crucibles, for polymerisations, a crucibles, in calorimeter, a film temperature probes filters, sintered furnace lining in election microscope, a in fuel cells, a mining at Rustenburg, increased output

O 8 potential on, a reflecting films, a resistance changed by HI, a resistivity after low-temperature

deformation, a

thermal expansion coefficient, a thermodynamic properties, a vapour pressure valve parts in space I.C. engine wave guide termination

Platinum-Aluminium, structure, a Platinum-Chromium, magnetic properties Platinum-Cobalt, magnetic properties, a

Platinum-Cobalt-Chromium, ordering, a Platinum-Cobalt-Manganese, ordering, a Platinum-Gold, effect of rhodium Platinum-Iridium, crucibles, a

viscosity of glass apparatus, a Platinum-Iron, expansion and elasticity, a Platinum-Iron, thermodynamic properties, a Platinum-Manganese, magnetic properties Platinum-Molybdenum, phase relations, a Platinum-Niobium, crystal data, a

superconducting phase, a Platinum-Palladium, absorption of

oxidation 50,

thermal conductivity standard 13,

Platinum Alloys,

permanent magnets

H Z and D,, a

29 114 30 70

148 107 107 107 107 147 109 109 1 1 1

2 82

141 73 29 90

122 110 110 146 54 12 33 36 49

107 33 73

107

108 107 107

70 134

8 15

147 9

147 82

147 147 133 74

114 29 70 9

147 148 148

147

Platinum Alloys (contd.) Page Platinum-Rhodium, durability of

apparatus, a effect of RhlOa, a furnace windings in X-ray diffractometer furnace, a losses in HNO? manufacture

Platinum-Silver, solid solutions, a Platinum-Tantalum, crystal data, a Platinum-Thorium, constitution, a Platinum-Tungsten, straln gauges

Platinum Complexes, a 31, Platinum Fluorides, propertics, a. Platinum Halides, thermodynamlc properties, Platinum Metals, alloy powders

carbonyl complexes, a fluorides, oxides, oxyfluorides, a in electrochemistry in fuel cells magnetic properties of alloys organometallic compounds oxidatjon, a oxyanions, a phthalocyanines reactions with carbon research by Klaus superconductivity, a superconductors, a

33 147

66, 98 74

127 70

148 71

128 72, 109

108 a 70

140 108 31 14 42

9 16

31, 107 31

143 101 67

108 31

Refractories, electrical resistance of 98 Resistance Thermometers, platinum,

Rhodium, coatings, stress and contamination miniature elements, a 115

55 crucibles, a 110, 149 effect on Au-Pt system 133 oxidation, a 107 resistivity after cold work, a 108 vapour pressure 134

32 31

Rhodium-Antimony, phase diagram, a 30 Rhodium-Arsenic, superconductivity, a 31 Rhodium-Bismuth, constitution, a 30 Rhodium-Copper, structure, a 108 Rhodium-Iron, magnetic properties 9, 59, 108 Rhodium-Manganese, magnetic properties 9 Rhodium-Nickel, mechanical properties, a 148

structure, a 71,108 Rhodium-Niobium, crystal data, a 148

superconducting phase, a 148 Rhodium-Palladium, effect of Rh eO J, a 147

magnetic susceptibility, a 29 Rhodium-Platinum, durability of

apparatus, a 33 effect of R h 2 0 s , a 147 furnace windings 66, 98

74 losses in HNO, manufacture I27

Rhodium-Tantalum, constitution, a 148 Rhodium-Thorium, constitution, a 71 Rhodium-Titanium, superconductivity, a 30, 108 Rhodium-Zirconium, superconductivity, a 30, 108

Rhodium Complexes, a 72, 109 Rhodium Oxides, decomposition, a 147

properties, a 109

Rhodium Acetate, preparation and properties, a Rhodium Alloys, with refractory metals, a

in X-ray diffractometer furnace, a

A Ruthenium, carbides not formed, a

corrosion resistance crucibles for polymerisations, a oxidation, a resistivity, a semiconductors with P, S, Se, Te, Sb, As, a vapour deposition, a vapour pressure, a 30, 134,

Ruthenium Alloys, with refractory metals, a Ruthcnium-Boron, crystal structure, a, Ruthcnium-Cerium, magnetic propertles

melting point of CeRuz, a Ruthenium-Gadolinium, magnetism and

Ruthenium-Iridium, phase diagram, a Ruthenium-Lanthanum, melting point

and superconductivity, a

superconductivity, a

of LaRu,, a

superconducting phase, a Ruthenium-Molybdenum,

Ruthenium-Nickel, mechanical properties, a Ruthenium-Kiobium, structure and

properties, a

susceptibility, a

point of PrRu2, a

reactor use, a structure, a

Ruthenium-Palladium, magnetic

Ruthenium-Praseodymium, melting

Ruthenium-Tantalum, for nuclear

Ruthenium-Thorium, constitution, a Ruthenium-Titanium, constitution, a Ruthenium-Tungsten, constitution, a

for nuclear reactor use, a Ruthenium-Zirconium, constitution, a

Ruthenium Chloride, preparation and magnetic

Ruthenium Complexes 72, 106, Ruthenium Oxides, at high temperature a

reaction of tetroxide with CaH,N, a Ruthenium Tetrafluoride, preparation and

Ruthenocene, deposition of R u film, a

Strain Gauges, in jet engines

Temperature Measurement, in steel making, a

Thermal Conductivity, Pt reference standard Thermocouples, early history

properties, a

properties, a

Pt film probes

Iridium :Iridium-Rhodium, in microfurnace. a reference tables, a

Palladium-Iridium-Platinum,

Pallador, in dew-point meter, a Platinel 11, reference tables and stability, a Platinum:Rhodium-Platinum, calibration

in steel making, a resistivity of refractorics apparatus viscosity of glass apparatus, a

Rhodium-Platinum :Rhodium-Platinum,

reference tables, a

in calorimeter, a

in steel making, a Tritium Labelling


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PLATINUM METALS REVIEW · down to magnesium (atomic number 12). ... fusible eutectic of platinum and rhodium- platinum silicide. This accounted for the fusing of the rhodium-platinum