,

SULFUR SENSITIVITY OF Pl'/RE CATALYSTS IN NAPHTHA REFORMING

BY

RONALD G. McCLUNG AND SONI o. OYEKAN

ENGELHARD CORPORATION SPECIALTY CHEMICALS DIVISION

MENLO PARK CN28 EDISON, NEW JERSEY 08818

PREPARED FOR PRESENTATION AT 1988 A.I.CH.E. SPRING NATIONAL MEETING

NEW ORLEANS, LOUISIANA KARCH 6 - 10

"RECENT ADVANCES IN CATALYTIC PROCESSES FOR PETROLEUM REFINING"

SESSION 44

COPYRIGHT ENGELHARD CORPORATION 2/88

Page 2

ABSTRACT

The role and state of platinum and rhenium in naphtha reforming

catalysts have been the subject of substantial research in the

last two decades. The role and effect of sulfur has not been

studied as extensivel y especially as they relate to normal

onstream operation of a commercial catalytic reformer.

This paper presents PtjRe catalyst performance data showing the

effects of feed sulfur on motor gasoline blending stock yields and

cycle l engths. These laboratory and commercial reformer data are

discussed with respect to published fundamental studies ' results

on the state of platinum and rhenium and the effects of sulfur on

bimetallic reforming catalyst performance.

Page 3

INTRODUCTION

Catalytic reforming of naphtha is used to produce high octane

motor fuel blending stocks, high purity hydrogen for

hydroprocessing units and aromatics for petrochemical use. With

phase-down of anti-knock additives and use of more paraffinic

naphthas, there is increasing demand on the refiners to produce

higher yields of gasoline boiling range aromatics and hydrogen

over catalysts with greater activity and selectivity stability.

The catalysts used in the reforming process are mainly the

platinum monometallic and the bimetallics . since the introduction

of platinum-rhenium cat alysts l in 1968, refiners have gradually

replaced their platinum catalysts with bimetallic composites

comprised of platinum promoted with either rhenium, iridium,

germanium or tin. Catalyst changeouts in many cases were prompted

by the demonstrated activity and selectivity stability of the

bimetallic catalysts over the monometallics. l , 3

Page 4

For the platinum and rhenium catalysts, the contributions of

rhenium in the bimetallics lead to greater reformate yield

stability and better catalyst life . It has been proposed by some

that sulfided platinum and rhenium catalysts are better than their

platinum analog as a result of the preferential chemisorption of

sulfur on the rhenium. 4 ,5

There have been other hypotheses suggested for the better activity

and selectiv ity stability of the platinum and rhenium catalysts

relative to the monometallic analogs . 6 , 7 , 8

Dautzenberg claimed that the effect of the second metal on

platinum i s geometric and pl atinum achieves better dispersion in

such s ystems. Wagstaff and Prins through their temperature

programmed r eduction studies suggested some form of "alloying" or

bimetallic aggr egation as being responsible for better platinum­

rhenium performance. One of the interesting conclusions of that

study was the fact that platinum could catalyze the reduction of

rhenium. Bertolaci ni a l s o s uggested that reasonably close

proximity i s desirable for the platinum and rhenium components as

page 5

determined in his study with mixtures of platinum and rhenium

extrudates. However, t he platinum and rhenium need not be in the

"alloy" or bimetallic "aggregate" form to provide the observed

improvements in catalyst performance over platinum only catalysts.

Bertolacini's as well as studies by other authors suggest that the

addition of rhenium to the platinum leads to reduced coking and

catalyst deactivation9,IO and increased activity and

selectivity. 11, 12

Page 6

STATE OF PLATINUM AND RHENIUM

The early work of JohnsonlJ led to many interesting studies on the

state of rhenium in the bimetallic composite and on the

reducibilty of rhenium. Othe r researchers7 ,14,lS,16,17 suggested

that rhenium could be reduced to its zero-valent state depending

on the pretreatment procedures utilized and the moisture content

of the catalyst environment . Further, that rhenium reduction to

the zero-valent state could be catalyzed by zero-valent platinum

and, in fact, result in bette r CS+ product selectivity in naphtha

reforming. 18

On the active state of rhenium during naphtha reforming there have

been very limited studies and the most important ones to date are

those by Bertolacini8 and Sachtler et al. 19 As discussed earlier,

Bertolacini showed mixed extrudates of platinum and rhenium

performed as favorably as extrudates of platinum-rhenium

catalysts. Further, Peri's infrared spectroscopic studies

suggested that platinum and rhenium sites co-exist and that they

are not "alloyed". In a recent paper, Sachtler et al, showed via

electron spin resonance (ESR) spectroscopy and CO adsorption

Page 7

studies that Reo and Re4+ species coexist on the surface of

Pt/Re/A1203 and the Re4+ species were less than ten percent of the

total rhenium. In all of the studies it is generally accepted

that platinum exists in the zero-valent state . Thus, the overall

conclusion that we can draw from these studies is that after

reduction and prior to sulfiding, the platinum and rhenium exist

probably as PtO , Reo, and Re4+ with the fraction of Re+ 4 being

less than five percent in the metals composite based on catalyst

pretreatment.

Page 8

PT/RE SULFUR SENSITIVITY STUDIES

The catalytic reforming process can be effected by the use of

platinum/Al203 catalysts promoted with rhenium, iridium, germanium

or tin. The bimetallic catalysts performances in the semi­

regenerative or cyclic regenerative reforming operations are

usually poorer than monometallic catalysts when feed sulfur levels

are in the 1-5 wppm range. Monometallic catalysts can withstand

sulfur levels in feeds greater than 5 wppm. However, it is

generally not advisable to continue to operate at high reforming

system sulfur level because of the negative influence of high

catalyst sulfur on rejuvenation of the active metal during

catalyst regenerations. In some cases this accumulation of sulfur

on reforming catalysts, which results in poorer catalyst

performance, can be removed by the application of a suitable

sulfur stripping procedure. 20

Sulfur compounds in naphtha vary with boiling range and these

compounds range from mercaptans to benzothiophenes. 2l

Organosulfur compounds that are present in naphthas are given in

Table I.

Page 9

Usually, depending on the naphtha hydro finer operation, feed

sulfur will be about 1 wppm sulfur. For balanced platinum/ rhenium

catalysts reforming operations, most vendors recommend that the

feed sulfur be less than 1 wppm. For t he high rhenium to platinum

(ratio >1.0) catalyst systems, feed sulfur specifications are

usually less than 0.5 wppm. The need to achieve lower sulfur in

reforming systems can be met with sulfur sorption technology if

the normal naphtha pretreatment and stripping process is

inadequate. 22

Many studies have focused on the effect of sulfur on platinum­

rhenium performance in model compound reforming

studies. 23 ,24,25,12 In some cases, these studies have been

conducted at low pressure (e.g. atmospheric pressure) and on

unsulfided catalysts. This combination of factors is far removed

from commercial reformer operation. Kokayeff ' s study,25 was

however, conducted at conditions designed ·to simulate commercial

reformer operations. In this paper we will use some of the basic

ideas contained in published papers to explain some of the data on

sulfur sensitivity we have accumulated via our pilot unit and

Page 10

commercial reformer studies. Generally, many of the published

studies are on the effects of catalyst sulfur and/ or feed sulfur

on catalyst activity and selectivity. In this paper, we seek to

extend our understanding on the effects of sulfur on catalyst

stability.

Page 11

PILOT PLANT AND COMMERCIAL DEVELOPMENTS

As noted in the previous section there are numerous publications

on the effect of pre-sulfiding sulfur on yields, but none

published on the quantitative effects of feedstock sulfur on

catalyst stability or run length.

Some definitions and comments are in order before presenting the

pilot plant and commercial evidence for the effect of sulfur on

bimetallic (Pt/Re) catalyst.

1. These data have all been generated on platinum/ rhenium

catalysts. No other bimetallic catalysts have been

considered.

2. The bimetallic catalysts are of two basic compositions. All

catalysts contain:

gamma-alumina

Chlorides

99 wt.%

1 wt.%

minus metals

Page 12

The metals compositions on each catalyst fall into two

categories - high rhenium catalyst and balanced rhenium

catalyst, for example:

CATALYST A

CATALYST B

PLATINUM (WT. %)

0.35

0.275

RHENIUM (WT. %)

0.35

0.775

CATALYST A is classified as a "balanced" platinum/rhenium

catalyst.

CATALYST B is classified as a "high" rhenium catalyst.

These differentiations are extremely important because of

differing sulfur sensitivities and resultant stability

improvements for sulfur reduction in the feed.

Page 13

3. Stability refers to the length of time onstream required to

reach a predetermined deactivation state - defined in this

work as follows:

"The time onstream required to reach a 2

volume percent yield difference/decline from

the start-of-run (SOR) pentane and heavier

(C5+) yield."

4. All the data illustrated is taken from constant octane runs

where the reactor temperature is raised to maintain gasoline

(C5+) octane, thereby compensating for catalyst

deactivation.

5. All the pilot plant runs were completed at accelerated aging

conditions.

WHSV = 4

RONC = 99

H2/HC = 3/1

Page 14

The graphs in Figure 2 thru 5 illustrate the effect of two

different feedstock sulfur levels on C5+ yield and temperature

requirement for catalyst A and B. The first feedstock used for

this testing is shown in Table II. The feed sulfur level is

changed by treating a portion of the naphtha over a commercially

available sulfur adsorbent.

Figure 1 shows typical catalyst deactivation for the balanced

bimetallic catalyst (CATALYST A) as measured using C5+ reformate

yield. The length of time required to reach 1 volume percent

yield decline is increased substantially by the reduction of feed

sulfur.

Correspondingly, in Figure 3, the temperature use curves

illustrate the increasing reactor temperature required to maintain

C5+ octane for the period of testing. Again the lower sulfur feed

shows a longer run length for a given increase in reactor

temperature.

Page 15

Figure ~ illustrates balanced bimetallic catalyst performance and

high rhenium catalyst (CATALYST B) performance. This graph

illustrates the C5+ yield stability benefit of high rhenium

catalyst over balanced bimetallic when high rhenium catalyst is

operated at low sulfur . This greater activity stability for

CATALYST B i s further illustrated in Figure 5 by the temperature

use curves.

Table III provides a summary of the relative stability benefits

for feedstock _I when processed over catalyst A and B. These

results ind i cate an approximately 170 percent stability advantage

for a bal anced bimetallic and over 200 percent for high rhenium

catalyst when approximately 50\ of the naphtha feed sulfur is

removed. A more dramatic result due to removal of sulfur is

observed for a feedstock of both high end point and high sulfur.

A commercial feedstock having these qualities is illustrated in

Table IV. For this feedstock over 70 percent of the naphtha feed

sulfur was removed. The effect of sulfur removal on catalyst A

and B performance i s illustrated in Figure 6 thru 9.

Page 16

Figure 6 depicts a very drastic decline of C5+ yield for CATALYST

A at 1.3 wppm and a very substantial improvement in performance by

removal of 70 percent of the feedstock sulfur. There is almost a

factor of 4 increase in cycle length as defined by yield decline.

Similarly, the temperature use curves in Figure 7 illustrate a

marked effect of reduction in feedstock sulfur on catalyst

deactivation.

The performance on feedstock *2 of the high rhenium catalyst

(CATALYST B) is illustrated in Figures 8 and 9. Here again, the

greater activity and selectivity stability are shown for operating

at low sulfur on high rhenium catalyst. The relative stability

results for this feedstock and the two catalysts tested are listed

in Table V.

Relative stability facts of approximately ~ are calculated from

actual run lengths for this feedstock as compared to more nearly a

factor of ~ for feedstock #1. Part of the discrepancy can be

accounted for by the lower sulfur level contained in feedstock #2

Page 17

at the low sulfur level (0.3 wppm for feedstock 12 and 0.6 wppm

for feedstock 11). However, the effect of sulfur removal on this

feedstock's performance is so pronounced that it must be a result

from the combination of high distillation end point and sulfur.

This phenomenon can probably be explained using an analogy drawn

from the experimental results of Kokayeff25 where he states:

"The presence of trace quantities of

sulfur drastically alters the relative

rates of aromatization and cracking of

n-decane over at PtjRe reforming catalyst.

In the presence of sulfur, the extent of

aromatization greatly increases while that

of cracking decreases. The C10 aromatics

thus formed can readily cyclize further to

indane and indene, which have been shown to

be very potent coke precursors".

Page 18

By analogy, the high carbon number paraffins (C10+) have more of a

tendency to form coke precursors in the presence of trace sulfur,

therefore the rate of deactivation is more pronounced for a

naphtha containing these compounds.

A reasonable method to correct the high sulfur case of Feed #2

for feedstock distillation high end point can be obtained from an

independent study at low sulfur. In this particular study, a

feedstock with high end point was run in a pilot plant. Then, a

cut of that feedstock, without the final 5% of the heavier

feedstock, was run.

Table VI illustrates feedstock inspections before and after

removal of the last 5 Vol.%.

The effect of the removal of these heavy ends on cycle length is

illustrated in Table VII. A relative stability factor of 1.6 is

calculated from the actual cycle lengths to quantify this end

point effect. Using this stability factor to modify for the heavy

end of Feed #2 gives results for the sulfur effect in closer

agreement with those for Feed #1. These modified stability

factors are given at the bottom of Table V.

page 19

Using the aforementioned data and others generated at Engelhard

over a number of years provides a general plot of relative

stability versus feedstock sulfur. This generalized plot is

illustrated in Figure 10 and shows that:

1. For balanced platinum-rhenium catalyst removal of sulfur

below 1 wppm in the feedstock has a relative stability

benefit of approximately 150%.

2. For high rhenium catalyst removal of sulfur below 1 wppm in

the feedstock has a relative stability benefit of

approximately 280%. The proof that these pilot plant derived

results are commercially achievable is illustrated in Table

VIII. The relative benefits expected for high rhenium

catalyst were easily obtained and exceeded by the illustrated

commercial data.

Page 20

DISCUSSION OF PILOT PLANT AND COMMERCIAL REFORMER DATA

The relative stability advantage of high rhenium over balanced

reforming catalysts and balanced Ptj Re over monometallic catalysts

can be attributed in large measure to the state of rhenium and the

"hydrocracking" activity of rhenium on surface-adsorbed coke

precursors. As suggested by Sachtler et a1 19 , the forms of the

active metals present on the catalyst surface are pto, Reo and

Re+4 . The Re+4 sites are probably strongly bound to the alumina

via surface-meta I-surface interaction, thus, precluding its

reduction to the zero-valent form. In the catalyst systems

studied, after the initial presulfiding sulfur has been stripped,

the sul fur from the feed is chemisorbed on the PtO and Reo sites.

It is also well known that sulfur is more "strongly" chemisorbed

on rhenium than on platinum. Thus, as the feed sulfur increases

the chemisorbed sulfur species would have a more significant

influence on rhenium's "hydr ocracking" activity than platinum's

hydrogen-dehydrogenation activity.

Page 21

Therefore, during reforming there is always an "equilibrium"

catalyst sulfur of about 0.03 to 0.10 wt.% sulfur which is

directly related to the rhenium content of the catalyst. As the

feed sulfur is increased more rhenium sites become covered with

sulfur precluding these rhenium sites from participating in the

desired "hydrocracking" of surface-adsorbed coke precursors.

In commercial application and pilot plant evaluations, the

performance of high rhenium catalysts are much more affected by

operation on a high sulfur naphtha than are balanced bimetallic

catalysts. Correspondingly, high rhenium catalyst performance is

more substantially affected by the reduction of sulfur. The

reason for this probably relates to rhenium's high sulfur

affinity. As previously stated, the sulfur on platinum/rhenium

catalyst directl y increases with rhenium level and the feedstock

sulfur level. This higher sulfur level on catalyst then begins to

affect the platinum activity and function, simply because of the

close proximity to platinum of the sulfur associated with the

rhenium - i.e. poss ibly even a sharing of sulfur between platinum

and rhenium. Therefore, in order to have an equilibrium or sulfur

level on the high rhenium corresponding to a figure less than or

equal to the sulfur on a balanced Pt/Re catalyst, the feedstock

sulfur specification must be correspondingly lower .

CONCLUSIONS AND RECOMMENDATIONS

Much of the published work for Pt/Re catalyst has adequately

described the effect of sulfur on the selectivity of such

catalyst. This paper has illustrated also the stability effects

of feedstock sulfurs at low concentrations and has shown

substantial benefits for removal of this sulfur.

REFERENCES

1. Kluksdahl, H.E., U.S. Patent 3,415,737 (1968)

2. Sinfelt, J.H., U.S. Patent 3,953,368 (1981)

3. Jacobson, R.L., Kluksdahl H.E., McCoy, C.S., & Davis R.W., in "Proceedings 34th Mid-year Mtg.", p504, Division Refining, Amer. Pet. Inst. (1969)

4. Biloen, P., Helle, J.N., Verbeek, H., Dautzenberg, F.M., & Sachtler, W.M.H., J. Catal 63, 112 (1980)

5. Sachtler, W.M.H., J. Mol Catal 25, 1 (1984)

6. Dautzenberg, F.M., 1979 Gordon Conference on Catalyses

7. Wagstaff, N. & Prins, R., J. Catal 59, 434 (1979)

8. Bertolacini, R.J., & Pellet, R.J., in Catalyst Deactivation ed. by Delmon, B. & Froment, G.F., Elsevier Pub. Co

9. Barbier, J., corro, G., Zhang, Y., Bournville, J.P., & Franck, J.P., App. Catal 16, 169 (1985)

10. Davis, B.H., Westfall, G.A., Watkins, J., Pezzanite, J.J., J. Catal 42, 247 (1976)

11. Bacaud, R., Bussiere, P., Figueras , F., J. Catal 69, 399 ( 1981)

12. Coughlin, R.W., Kawakami, K., Hassan, A., J . Catal, 88, 150 ( 1984)

13 . Johnson, M.F.L. & LeRoy, V.M., J. Catal 35, 434 (1974)

14. McNicol, B.D., J. Catal, 46, 438 (1977)

15. Webb, A.N., J. Catal, 39, 484 (1975)

16. Charcosset, H. , Bolivar, C., Froty , R., Primet, M., Tounnayan, L., J. Catal 45, 463 (1978)

References (con'tl

17. Sce1za, O.A., De Miguel, S.R., Baronetti, G.T. & Castro, A.A., React. Kinet. Cata1 Lett. 21 (1) 143 (1987)

18. Oyekan, S.O., U.S. Patent 4,539,307 (1985)

19. Nacheef, M.S., Kraus, L.S., Ichikawa, M., Hoffman, B.M., Butt, J.B., & Sachtler, W.M.H., J. Catal 106, 263 (1987)

20. Tse, H.F., U.S. Patent 4,377,495 (1981)

21. Gates, B.C., Katzer, J.R., & Schmit, G.C.A., Chemistry of Catalytic Processes, p392, 1979 McGraw-Hill, New York

22. McClung, R.G. & Novak, W.J., Paper AM-87-47 NPRA Annual Meeting, San Antonio, 1987

23. Menon, P.G., & Prasad, J., sixth International Congress on " Catalysis, The Chemical Society, London, 1977

24. Menon, P.G., Marin, G.B., & Froment, G.F., Ind. Eng. Chem. Prod. Res. Der. 21 (1) 52-56 (1982)

25. Kokayeff, P., Paper 46C, AIChE Annual Meeting, New York, 1987

TABLE 1

SULFUR - CONTAINING COMPOUNDS IN NAPHTHAS

COMPOUND TYPE STRUCTURE BOILING RANGE (OF)

THIOLS (MERCAPT ANS) RSH 150+

DISULFIDES RSSR' 180+

SULFIDES RSR' 180+

THIOPHENES 184+ \

OR 0 S S

O::J R

BENZOTHIOPHENE 430'+

TABLE II

FEED 1

API GRAVITY , 54.7

ASTM DISTILLATION, of

IBP 136 10% 193 50% 250 90% 320 95% 334 EP 346

TYPE ANALYSIS, VOL %

PARAFFINS 38.2 NAPHTHENES 48.2 AROMATICS 13.6

TABLE III

PILOT PLANT DATA RESULTS

FEED 1

CATALYST A CATALYST A CATALYST B 1.3 WPPM 0.6 WPPM 0.6 WPPM FEED SULFUR FEED SULFUR FEED SULFUR

C5+ YIELD 2 VOLUME % DECLINE 220 HRS. 390 HRS. 465 HRS.

RELATIVE STABILITY FACTORS BASED ON:

C5+ YIELD DECLINE 1.00 1.77 2.11

TABLE IV

FEED 2

GRAVITY, °API 54.3

ASTM DISTILLATION, of

IBP 158 5% 197

10% 214 50% 292 90% 380 95% 401 FBP 432

ANALYSIS, VOLUME %

PARAFFINS 46 NAPHTHENES 29 AROMATICS 25

TABLE v PILOT PLANT DATA RESULTS

FEED 2

CATALYST A CATALYST A CATALYST B 1.3 WPPM 0.3 WPPM 0.3 WPPM FEED SULFUR FEED SULFUR FEED SULFUR

2 VOL % C5+ YIELD DECLINE (HRS) 66 256 284

RELATIVE STABILITY FACTORS BASED ON:

C5+ YIELD DECLINE 1.0 3.88 4.30

CORRECTED FOR HIGH END POINT

2 VOL % C5 + YIELD DECLINE HOURS 106 256 284

RELATIVE STABILITY FACTOR BASED C5+ YIELD DECLINE 1.0 2.4 2.7

TABLE VI

EFFECT OF FEEDSTOCK ON

CATALYST STABILITY - FEEDSTOCK INSPECTIONS

BASE CASE TOP 95% OF FULL NAPHTHA BASE CASE

API GRAVITY 58.9 59.7

ASTM DISTILLATION, of IBP 152 152 10 180 185 50 229 225 90 316 297 95 338 312 FBP 378 342

TYPE ANALYSIS, VOL 0/0

PARAFFINS 51.2 54.1

NAPHTHENES 36.3 34.6 AROMATICS 12.5 11.3 SULFUR (WPPM) <0.2 <0.2

TABLE VII

EFFECT OF FEEDSTOCK ON

CATALYST STABILITY - RELATIVE STABILITY

HOURS FOR 2.0 VOL% C5 + YIELD DECLINE

FULL NAPHTHA

207

RELATIVE STABILITY = 331 HRS = 1.6 207 HRS

TOP 95%

331

TABLE VIII

COMMERCIAL PERFORMANCE WITH HIGH RHENIUM CATALYST

RONC

FEEDRATE, BPSD

WHSV, HR·1 AVG RX PRES, PSIG

SEPARATOR PRES, PSIG

H2/HC

CYCLE LENGTH

FEED SULFUR

NOTE:

ACTUAL DATA

100

18000

1.66 194 142 5.5

11 MONTHS

LESS THAN 0.1 WPPM

CYCLE TERMINATED DUE TO YEARLY TAR, PREDICTED CYCLE FOR HIGH Re CATALYST IS 12 MONTHS PREDICTED CYCLE FOR BALANCED CATALYST IS 5 MONTHS

RELATIVE STABILITY PROVEN = .!!. = 2.2 5

RELATIVE STABILITY PREDICTED = 2.0

FIGURE 1

TPR of Ptl A120 3, ReI AI20 3 and Pt-Rel AI20 3

SAMPLE

1

o 200 400 600

REDUCTION TEMPERATURE, °C

SCELZA at al.: Pt.Ra/AI20 3 CATALYSTS

FEED 1

o

-1 w z ::::i

-2 0 w c C ...I w :;: -3

S. w

-4 == :::) ...I 0 > + - 5 ." 0

FIGURE 2

PILOT PLANT DATA C5 + YIELD DECLINE VS. HOURS ON STREAM

FEED CATALYST A CATALYST A SULFUR = FEED 1.3 WPPM SULFUR =

0.6 WPPM

100 200 300 400 500 600

TIME ON STREAM, HOURS

FEED 1

80

70

U-60 0

w U) <I(

50 w a:: 0 z w 40 a:: ::::I I-<I( 30 a:: w Q.

~ 20 w I-

10

0

FIGURE 3

PILOT PLANT DATA TEMPERATURE RISE VS. HOURS ON STREAM

CATALYST A CATALYST A FEED SULFUR = 1.3 WPPM FEED SULFUR = 0.6 WPPM

100 200 300 400 500 600

TIME ON STREAM, HOURS

FEED 1

o

-1

w z :::;

- 2 () w 0 0 ..J

-3 w >= S. w -4 ~ ~ ..J 0 > -5 + \I) ()

- 6

FIGURE 4

PILOT PLANT DATA C5 + YIELD DECLINE VS. HOURS ON STREAM

CATALYST B FEED SULFUR = 0.6 WPPM

CATALYST A FEED SULFUR = 1.3 WPPM

100 200 300 400 500 600 TIME ON STREAM, HOURS

IL o

w (/) e( w a: o z

FEED 1

80

60

w 40 a: ~ l-e( a: w a. =: ~. 20

FIGURE 5

PILOT PLANT DATA TEMPERATURE RISE VS. HOURS ON STREAM

CATALYST A FEED SULFUR = 1.3 WPPM

CATALYST B FEED SULFUR = 0.6 WPPM

O~------~------~------~------~------~-----J 100 200 300 400 500 600

TIME ON STREAM, HOURS

FEED 2

0 w z -1 ::::i 0 w -2 0 0 ....I -3 w >= ;f! -4 w :::!E -5 :) ....I 0 -6 > + ." 0

40

FIGURE 6

PILOT PLANT DATA C5 + YIELD DECLINE VS. HOURS ON STREAM

CATALYST A 0.3 WPPM

CATALYST A FEED SULFUR 1.3 WPPM

FEED SULFUR

80 120 160 200 240 280 320 360 400

HOURS ON STREAM

FEED 2

80

70

II. 60 0

w Ul 50 ~ w a: 40 0 ~ w 30 a: :::) I- 20 ~ a: w 10 CL ~ W 0 I-

40

FIGURE 7

PILOT PLANT DATA TEMPERATURE RISE VS. HOURS ON STREAM

CATALYST A 1.3 WPPM

FEED SULFUR CATALYST A

0.3 WPPM FEED SULFUR

80 120 160 200 240 280 320 360

HOURS ON STREAM

400

FEED 2

w z :J 0 w 0 Q

Q ...J - 1 w > ;f. -2 w ::E -3 :::I ...J 0 -4 > + -5 It) .

0

- 6

40

FIGURE 8

PILOT PLANT DATA C5 + YIELD DECLINE VS. HOURS ON STREAM

CATALYST B 0.3 WPPM FEED SULFUR

CATALYST A 1.3 WPPM FEED SULFUR

80 120 160 200 240 280 320 360

HOURS ON STREAM

FEED 2

80

u. 70 0

w II) 60 c( w a: 50 0 z w 40 a: ::l t- 30 c( a: w 20 ' 11. ~ W 10 t-

O

40

FIGURE 9

PILOT PLANT DATA TEMPERATURE RISE VS. HOURS ON STREAM

CATALYST A CATALYST B 1.3 WPPM 0.3 WPPM FEED SULFUR FEED SULFUR

80 120 160 200 240 280 320 360 400

HOURS ON STREAM

FIGURE 10

GENERALIZED RELATIVE STABILITY FOR PT/RE CATALYST

2.6

2.4

2.2

2.0

~ 1.8

0 1.6 HIGH RHENIUM ~

0 c(

1.4 u.. > ~ 1.2 :::::i iD

1.0 c( ~ fJ)

0.8

0.6

0.4

0.2

0.0 1 2

• FEED SULFUR (WPPM)

, .