Catalyst Efficacy

8/13/2019 Catalyst Efficacy

1/6

Experimental study on two-stage catalytic hydroprocessing

of middle-temperature coal tar to clean liquid fuels

Tao Kan, Hongyan Wang, Hongxing He, Chunshan Li , Suojiang Zhang

State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, PR China

a r t i c l e i n f o

Article history:

Received 25 March 2011

Received in revised form 7 June 2011

Accepted 12 June 2011

Available online 22 June 2011

Keywords:

Middle-temperature coal tar

Hydroprocessing

Oil

Two-stage

Catalyst

a b s t r a c t

Special MoCo/c-Al2O3and WNi/c-Al2O3catalysts with different metal loadings were prepared applying

new synthesis technologies that combine ultrasonic-assisted impregnation and temperature-program-

ming methods. Clean liquid oil was obtained from middle-temperature coal tar via hydrogenation in

two-stage fixed beds filled with the laboratory made catalysts. The MoCo/c-Al2O3 catalyst with

12.59 wt.% Mo and 3.37 wt.% Co loadings, and the WNi/c-Al2O3 catalyst with 15.75 wt.% W and

2.47 wt.% Ni loadings were selected. The effects of pressure and liquid hourly space velocity on hydroge-

nation performance were investigated while other experimental conditions remained constant. Gasoline

(6180C) and diesel (180360 C) fractions were separated from the oil product and analyzed. The two-

stage reacting system was capable of removing nitrogen and sulfur from 1.69 and 0.98 wt.% in the feed to

less than 10 ppm and 100 ppm, respectively in the products. The results indicated that the raw coal tar

could be considerably upgraded through catalytic hydroprocessing and high-quality fuels were obtained.

2011 Elsevier Ltd. All rights reserved.

1. Introduction

In view of growing concerns about the petroleum depletion cri-

sis and rising fuel price, major efforts are being dedicated to the

development of various usable energy sources to ensure energy

security. China is one of the largest coal producers in the world

and extensive studies have been focused on the fuel production

from coal[14]. Abundant coal tar has been produced every year

during coal carbonization and gasification[5]. The coal tar can be

used as an alternative source for producing conventional liquid

fuels (e.g., gasoline and diesel) through its hydrogenation. On the

other hand, liquid fuel production is currently subject to strict

environmental standards for transport liquid fuels and refractory

feeds for refiners [6]. Environmental and economic benefits are

inevitably linked to the hydroprocessing of coal tar to produce

clean transport fuels with ultra-low heteroatom content.

Coal tar is a complex mixture consisting of aliphatic, aromatic,

alicyclic, and heterocyclic compounds. The complexity of coal tar

has driven researches that focused on a pure model compound,

such as naphthalene [710], phenanthrene [10], anthracene [11],

and quinoline[12], rather than on a real fraction. Extensive inves-

tigations on thermodynamics and kinetics have been performed

[1316]. Detailed reviews of studies on the reaction networks have

been provided by Girgis and Gates[17]. The kinetics of the removal

of sulfur compounds and other impurities has a critical effect onthe optimization of process variables and the selection of catalyst

for hydrodesulfurization (HDS), hydrodenitrogenation (HDN), and

hydrodeoxygenation (HDO) processes [6]. Although studies de-

scribed above are helpful in understanding the behavior of certain

compounds under hydroprocessing conditions, an overall picture

of coal tar hydrogenation was not provided. At the temperature

and pressure required for hydrotreatment, many undesirable reac-

tions including dehydrogenation, polymerization, isomerization,

and condensation would occur[18].

The performance of hydroprocessing units is greatly influenced

by the catalyst, type of reactor, process flow, and operating param-

eters. Physical properties such as the density, porosity, size, and

shape of a catalyst are crucial parameters in hydroprocessing heavy

feeds [19]. These parameters arefeed dependent [20], implying that

for certain coal tar feedstock, catalysts with special properties (usu-

ally high BET surface and large pore volume) are required. MoCo

supported on alumina has long life, and under suitable conditions,

enables the removal of a high degree of sulfur with little more than

theoretical hydrogen consumption[21]. Also, in the study by Raje

et al., the hydrotreatment of coal-derived naphtha was evaluated

over unsupported transition metal sulfide catalysts of Group VIII

in the Periodic Table, and ruthenium sulfide (RuS2) was found to

be the most active catalyst for the heteroatom removal[22]. Fur-

thermore, a low loading Ru/zeolite catalyst was believed to exceed

the commercial MoCo and MoNi catalysts in HDN activity per

weight of metal and price[23]. But it showed a much lower HDS

activity. Tungsten sulfide has been claimed as an effective catalyst

0016-2361/$ - see front matter 2011 Elsevier Ltd. All rights reserved.doi:10.1016/j.fuel.2011.06.012

Corresponding authors. Tel./fax: +86 10 82547800 (C. Li), +86 10 82627080

(S. Zhang).

E-mail addresses:[email protected](C. Li),[email protected](S. Zhang).

Fuel 90 (2011) 34043409

Contents lists available at ScienceDirect

Fuel

j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / f u e l
http://dx.doi.org/10.1016/j.fuel.2011.06.012mailto:[email protected]:[email protected]://dx.doi.org/10.1016/j.fuel.2011.06.012http://www.sciencedirect.com/science/journal/00162361http://www.elsevier.com/locate/fuelhttp://www.elsevier.com/locate/fuelhttp://www.sciencedirect.com/science/journal/00162361http://dx.doi.org/10.1016/j.fuel.2011.06.012mailto:[email protected]:[email protected]://dx.doi.org/10.1016/j.fuel.2011.06.012


2/6

for a wide variety of hydrocarbon reactions including the hydroge-

nation of olefins and aromatics, and isomerization of naphthenes

and paraffins, as well as hydrocracking and hydrogenolysis[24]. It

is believed that creating smaller particles of active metals will im-

prove the catalysts activity. Some recent studies[2528]have dis-

cussed the synthesis of highly dispersedc-Al2O3-supported MoCo

catalysts using energy from ultrasonic waves.

The present study describes the bench scale two-stage hydro-processing of middle-temperature coal tar using laboratory made

MoCo and WNi catalysts supported on c-Al2O3 in the first and

second stages respectively. Impregnation and temperature-pro-

gramming technologies were applied to prepare the catalysts. This

work primarily aims to reduce heteroatoms (S, N, and O) and pro-

duce high-quality liquid fuels under varied reaction pressures and

liquid hourly space velocities (LHSV). The coupling of hydrofining

for initial hydrogenation in the first stage and hydrocracking for

further hydrogenation and CAC bond cracking in the second stage

showed promising results.

2. Experimental

2.1. Catalyst preparation and characterization

Hydrofining catalysts (MoCo/c-Al2O3) with different Mo and

Co loadings were prepared and the synthesis procedure is de-

scribed as follows: (1) Pretreatment. The commercialc-Al2O3gran-

ules of 2040 mesh were used as the catalyst support. Higher

surface area of the alumina granules was obtained after they were

dipped in the 5 wt.% diluted HCl solution for 20 min. Then they

were dried at 110C for 2 h to get rid of the surface water, after

which they were calcined at 500 C for 6 h to eliminate the water

absorbed in the pores and stabilize the framework of the alumina.

(2) Ultrasonic impregnation. The support was impregnated in an

aqueous solution containing the required amount of ammonium

molybdate [(NH4)6Mo7O244H2O] and cobalt nitrate [Co(N-

O3)26H2O] for 12 h. During the impregnation process, ultrasonicvibration with a frequency of 50 kHz was applied. Then the Mo

and Co precursors will be highly dispersed on the pretreated c-

Al2O3 support using energy from ultrasonic waves. (3) Tempera-

ture-programmed treatment. The catalyst was heated in the air

atmosphere to the temperature of 200C and held for 3 h. Then

it was heated to 350C at a rate of 5 C/min and held for 3 h, which

was finally heated to 500C at a rate of 10C/min and held at this

temperature for 6 h. The hydrocracking catalysts (WNi/c-Al2O3)

with different W and Ni loadings were also synthesized under

the same procedure using the precursors of ammonium metatung-

st ate hydrat e [H40N10O41W12XH2O] and nickel nitrat e

[Ni(NO3)26H2O].

The amount of various metals present on the catalysts was ana-

lyzed using ICP-AES (IRIS Intrepid II XSP, ThermoFisher Co., Ltd.).The BET surface area and pore volume measurements of the cata-

lysts were performed with adsorption equipment (Micromeritics)

using N2 gas. X-ray diffraction (XRD) was performed using a dif-

fractometer (XPert PRO MPD, PANalytical Co., Ltd.) with Cu Ka

radiation filtered by a graphic monochromator at a setting of

40 kV and 40 mA. High resolution transmission electron micros-

copy (HRTEM, model: JEM-2100, JEOL Co., Ltd.) was also performed

to investigate the structure of the catalysts.

Catalysts with different metal loadings were evaluated in the

tests of coal tar hydroprocessing. After preliminary screening tests,

the hydrofining catalysts (MoCo/c-Al2O3) with 12.59 wt.% Mo and

3.37 wt.% Co loadings, and the hydrocracking catalyst (WNi/c-

Al2O3) with 15.75 wt.% W and 2.47 wt.% Ni loadings showed better

performance than did the other catalysts. Thus, they were finallyused in the following experiment.

2.2. Feedstock

The distillate (under 360C) of the middle-temperature coal tar

was used as feedstock in this study. Some properties of the feed-

stock are listed inTable 1.

2.3. Reaction system

The hydroprocessing of the coal tar was carried out in a contin-

uous two-stage fixed-beds system. As shown inFig. 1, the entire

reaction systemwas mainlymade up of three units, i.e., thereactant

feeding, the hydrogenation, and the product separation and collec-

tion units. The reactant feeding unit consisted of a tar supply line

and a high-pressure hydrogen supply line. The hydrogenation unit

consisted of a preheater, a hydrofining reactor, and a hydrocracking

reactor. The middle section of each reactor tube was filled with

30 ml catalyst. The product separation and collection unit included

a water cooler, a gasliquid separator, a lye washer and so on.

2.4. Operating procedure and product analysis

Coal tar hydroprocessing was conducted as follows: (I) Pre-sulf-

idation of catalysts. The sulfidation of catalysts was performed at

PH2 = 6 MPa, LHSV = 1.6 h1, and H2/oil ratio = 1000 using 2 wt.%

dimethyl disulfide in aviation kerosene and underwent a tempera-

ture-programmed procedure. (II) Hydroprocessing tests. All the

experimental parameters were set at the respective desired values

and the tests were conducted at a duration of 120 h. (III) The over-

all system was washed with ethanol after each run.

The liquid product was distilled into gasoline (6180C), diesel

(180360 C) and residue oil (>360 C) fractions. The samples of

gasoline and diesel fractions were then subjected to the following

analyses: (i) determination of distillation range by the Engler dis-

tillation method (standard: ASTM D86); (ii) C and H elemental

analyses on an Elementar VARIO ELIII (Germany), N and S analyses

on KY-3000SN (Jiangsu Jiangyan KEYUAN Electronic Instrument

Co. Ltd., standard: ASTM D5453 and D4629); (iii) density onDMA 5000 (Anton Paar, Austria); (iv) research octane number

(RON) and anti-knock index (AKI) for gasoline; (v) cetane number

and solidifying point for diesel; and (vi) detailed composition

determined by capillary column GCMS analysis (Agilent 6890N

with a 30 m0.25 mm0.25 lm HP-5MS capillary column).

3. Results and discussion

3.1. Catalyst characterization

As shown in Table 2, both the MoCo/c-Al2O3 and WNi/c-

Al2O3 catalysts had a BET surface area of200 m2/g and a pore

Table 1Properties of coal tar fraction.

Properties Value

Elemental analysis (wt.%)

C 84.86

H 8.39

N 1.69

S 0.96

Oa 4.10

H/C molar ratio 1.19

Distillation range (C)

IBP 118

10% 196

50% 261

90% 306

Density (20C) (g mL1) 1.0078

a By difference.

T. Kan et al./ Fuel 90 (2011) 34043409 3405


3/6

volume of higher than 0.5 cm3/g. The XRD patterns (not shown

here) of both fresh catalysts exhibited only very broad XRD lines

of thec-Al2O3support and did not show any obvious special peaks

other than the c-Al2O3 support, indicating that for both catalysts,

all the metal oxides were highly dispersed over the support and

their particle sizes are below the detection limit of XRD. These re-

sults are well consistent with those of previous studies[6,2526].

The TEM micrographs of the fresh MoCo and WNi catalysts were

shown inFig. 2A andFig. 2B respectively. The presulfurized MoCo

and WNi catalysts were also analysed by TEM as exhibited in

Fig. 2C and D. It could be concluded that the active metals and pro-moters were highly dispersed on the alumina support.

3.2. Comparison between intermedial and final products

In order to certify the necessity of two-stage hydroprocessing

and the catalysis effect by the downstream WNi/c-Al2O3catalyst,

the intermedial product after the first reactor was analysed and

compared with the final product after the second reactor. Both

the products were distilled into gasoline, diesel, and residual oil

fractions and the comparison between the intermedial and the fi-

nal products was shown inTable 3. Some heteroatom-containing

compounds such as aniline, substituted phenols, and benzyl alco-

hols still remained in the intermedial product according to the

GCMS analysis. These results indicated that the two-stage processand the downstream WNi/c-Al2O3 catalyst were essential for

obtaining high hydroprocessing performance (e.g., yields and prop-

erties of gasoline and diesel products).

3.3. Effect of pressure on product properties

The most important process variables, which generally affect

the hydroprocessing performance, are temperature, pressure,

hydrogen-to-oil ratio, and LHSV. Operation at very high tempera-

tures is undesirable, and the catalyst should be operated at tem-

peratures below 400 C[29].

In current study, the experimental conditions such as hydrofin-

ing temperature (Thf) of 360C, hydrocracking temperature (Thc) of

380C, and hydrogen to coal tar volume ratio (H2/oil ratio) of 1600were kept constant. Other conditions including reaction pressure

PH2 and LHSV were varied in the range of 612 MPa and 0.4

1.2 h1 respectively to investigate their effects on the hydropro-cessing performance.

As shown inTable 4the influence of pressure on the hydropro-

cessing performance was investigated at stepwise pressures of 6, 8,

and 12 MPa. The nitrogen conversion reached a very high level

with a nitrogen content of only 3 ppm remained in the produced

gasoline and 1 ppm in the diesel under the pressure of 12 MPa.

These data indicated that HDN is a strong function of hydrogen

pressure. The preferred reaction pathway for HDN reaction initially

involves the saturation of the aromatic ring carrying the hetero-

atom (especially for compounds in which nitrogen is part of the

aromatic ring) before CAN bond scission takes place [17,29,30].

The removal of nitrogen compounds contained in coal-derived

naphtha was also well investigated by Liaw et al. [31].

The most significant HDS for environmental attention exhibitedthe same changing trend as did the HDN. As the pressure was

raised from 6 to 12 MPa, the sulfur content changed from 71 to

66 ppm and 54 to 24 ppm in the gasoline and diesel products

respectively. The HDS reaction network proceeds by a similar

mechanism through direct hydrogenolysis or through the hydroge-

nation of the aromatic ring prior to sulfur removal [29]. It can be

also concluded from Table 4 that pressure influences the HDN

activity to a greater extent than the HDS activity, which indicated

that the rate constant for HDN is higher than the value for HDS. In

the kinetic study by Vishwakarma et al.[6], the higher HDN reac-

tion rate than HDS could be explained as that the HDN was not

inhibited by pore diffusion while the HDS was the opposite. On

the other hand, basic nitrogen-containing compounds are well

known to have strong inhibition effect on the HDS reaction. For along time, the nature of the inhibition remained unclear but

Fig. 1. Schematic diagram of the reaction system for coal tar hydrogenation.

Table 2

Catalyst characterization.

Catalyst Composition (wt.%) BET area

(m2/g)

Pore vol.

(cm3/g)Mo Co W Ni

MoCo/c-Al2O3 12.59 3.37 217 0.58

WNi/c-Al2O3 15.75 2.47 192 0.52

3406 T. Kan et al./ Fuel 90 (2011) 34043409


4/6

recently scanning tunnelling microscopy (STM) and density func-tional theory (DFT) studies on the unsupported MoS2-based cata-

lysts have provided new detailed atomic-scale insight into the

nature of the inhibition effects, which revealed that the metallic

like brim sites located adjacent to the edges were involved in the

hydrogenation and CAS bond scission reactions in HDS [3235].

It was found that inhibition by nitrogen-containing compounds

was due to not only blocking but also reducing the number of H

atoms available for hydrogenation[36]. As to the supported cata-

lysts, a few studies have investigated support effects by modelling

promoted and unpromoted MoS2-based cluster structures on

different facets of c-Al2O3, and in the latter studies different

adsorption geometries and configurations were mapped out in

great detail[34]. For the Co or Ni promoted Mo catalyst, the inter-

actions among Mo, the promoter, and the support will exhibitmore complexity. Comparing to the unsupported catalysts, such

investigations of the catalyst involvingc-Al2O3support are compli-

cated further by the fact that the precise location of non-spinelsites in c-Al2O3is not completely known and still under discussion

[34].

As to the HDO, the oxygen contents in the gasoline and diesel

products were evidently reduced to 0.51.5 wt.% (not shown in

the tables) comparing to the oxygen content of 4.10 wt.% in the

feed. The heating values of the produced fuels were strongly

dependent on their oxygen content and the higher heating value

(HHV) of the liquid fuels can be approximately calculated from ele-

mental data using the corresponding equation[37].

At the same time, there also occurred an increase in H/C molar

ratio and a reduction in the boiling range, indicating enhanced aro-

matic saturation and hydrocracking under higher pressure. The

rate-controlling step in the hydrogenation reaction appears to be

the orientation and adsorption of the reactants on the catalyst sur-face[11]. At higher pressure, more hydrogen gas dissolved into the

reactant oil, moved onto the catalyst surface, participated in the

hydrogenation reaction, and finally entered into the product.

The decrease in density at higher pressure can be ascribed to the

effect of a lower aromatic content caused by enhanced aromatic

saturation. Increasing the pressure from 6 to 12 MPa resulted in

the downgrade of RON and AKI for the gasoline product and cetane

value for the diesel product. This downgrade may be caused by the

excessive hydrogenation of the feedstock at higher pressure.

3.4. Effect of LHSV on product properties

LHSV reflects the contact time of the tar with the catalysts. For

the same catalyst bed, a higher LHSV value will result in shortercontact time. In the serial tests, three typical LHSV values of 0.4,

Fig. 2. TEM micrographs of catalyst samples: (A) the fresh MoCo catalyst; (B) the fresh WNi catalyst; (C) the presulfurized MoCo catalyst; and (D) the presulfurized WNi

catalyst.

Table 3

Comparison between intermedial and final productsa.

Product

properties

Gasoline Diesel

Intermedial

product

Final

product

Intermedial

product

Final

product

Yield (vol.%) 13.7 20.1 75.0 76.9

S & N analysis (wt.%)

S (ppm) 244 71 457 54

N (ppm) 352 14 422 8

H/C molar

ratio

1.76 1.81 1.43 1.71

a Experimental conditions: PH2 = 6 MPa, Thf=360C,Thc=380C, LHSV = 0.4 h1,

and H2/oil ratio=1600.

T. Kan et al./ Fuel 90 (2011) 34043409 3407


5/6

0.8 and 1.2 h1

were selected and other experimental parameterssuch as PH2 = 6 MPa, Thf= 360 C, Thc=380 C, and H2/oil ra-

tio=1600 were kept constant.

As shown inTable 5,the gasoline yield slightly decreased from

20.1% to 18.7% with increasing the LHSV from 0.4 to 1.2 h1. The

sulfur and nitrogen concentrations in the gasoline product rose

with increasing LHSV, accompanied by a drop in H/C molar ratio

from 1.81 to 1.72 due to the less reaction time provided for HDS

at higher LHSV. The density as well as the RON and AKI indexes

was also slightly elevated with increasing the LHSV. However,

the distillation range was not evidently influenced by the LHSV.

As can be concluded fromTable 5, similar results were obtained

for the diesel product.

During the hydroprocessing of the coal tar, the hydrogenation

reaction involving in three phases proceeds at a very slow rate.For this multistep hydrogenation reaction, enough reaction time

is apparently necessary. At higher LHSV, maybe not enough time

was provided to ensure the occurrence of certain reactions.

3.5. Components in gasoline and diesel products

The organic components in the gasoline and diesel products

were determined by GCMS analysis. The most abundant compo-

nents in the gasoline product included C6AC8 hydrocarbons, such

as cyclohexane, substituted cyclohexanes, and toluene. Methyl-

cyclohexane (C7H14) appeared as the most outstanding component

with a molar content of 12.48%. The gasoline fraction mainly con-

sisted of monocyclic aromatics, alkenes, and saturated ring com-

pounds. Bicyclic substituted naphthalenes with low contents

were also detected. For the diesel product, more than 300 peaks

were successfully detected. Various bicyclic and polycyclic aromat-

ics (e.g., naphthalene, anthracene, and phenanthrene) as well as

straight-chain alkanes with high carbon numbers (e.g., heptadec-ane) appeared in the diesel fraction. Hexadecane was the most

abundant material with molar content of 2.36%.

3.6. Functional groups in gasoline and diesel products

The FTIR analysis was were employed to study the organic

groups existing in the coal tar, the gasoline, and diesel products

as presented inFig. 3. For the coal tar (Fig. 3A), the absorption band

from 3690 to 3100 cm1, the peaks at 2920 cm1, 1460, and

1380 cm1, the peak at 1600 cm1, and the peaks at 812 and

752 cm1 were attributed to the OAH stretching vibrations, the

presence of alkanes, the existence of C@C bonds, and the presence

of polycyclic and substituted aromatic groups respectively. For the

gasoline (Fig. 3B), and diesel (Fig. 3C) products, two similar FT-IRspectra with different intensities of peaks were obtained. Compar-

ing to the coal tar, some changes occurred: (1) The disappearance

of the band between 3690 and 3100 cm1 showed the removal of

OAH group via HDO. (2) The peak at 2920 cm1 for the alkanes be-

came stronger, accompanied by the relatively smaller peaks at

752 cm1, indicating the increasing content of alkanes and the

reduction of aromatic groups. (3) The peak at 1600 cm1 almost

vanished, indicating the decrease of the C@C compounds.

4. Conclusion

Special hydrofining (MoCo/c-Al2O3) catalyst with 12.59 wt.%

Mo and 3.37 wt.% Co loadings and hydrocracking (WNi/c-Al2O3)

catalyst with 15.75 wt.% W and 2.47 wt.% Ni loadings were pre-pared applying combined synthesis technologies of ultrasonic-as-

Table 4

Effect of pressure on properties of gasoline and diesel productsa.

Product properties Effect of pressure on

gasoline

Effect of pressure on

diesel

6

(MPa)

8

(MPa)

12

(MPa)

6

(MPa)

8

(MPa)

12

(MPa)

Yield (vol.%) 20.1 20.3 22.3 76.9 73.2 70.1

S & N analysis (wt.%)S (ppm) 71 66 66 54 44 24

N (ppm) 14 12 3 8 2 1

H/C molar ratio 1.81 1.91 1.98 1.71 1.80 1.89

Distillation range (C)

IBP 95 90 80 / / /

10% 122 114 113 / / /

50% / / / 275 273 253

90% / / / 343 340 320

FBP 286 283 274 360 358 355

Density (20C)

(gmL1)

0.8060 0.8035 0.7941 0.8863 0.8750 0.8444

RON 93.0 92.9 91.2 / / /

AKI 88.2 88.2 86.7 / / /

Cetane value / / / 56.2 42.4 35.6

Solidifying point

(C)

/ / / +4.3 14.9 29.1

a Other experimental conditions: Thf=360C, Thc=380C, LHSV = 0.4 h1, and

H2/oil ratio=1600.

Table 5

Effect of LHSV on properties of gasoline and diesel productsa.

Product properties Effect of LHSV on gasoline Effect of LHSV on diesel

0.4

(h1)

0.8

(h1)

1.2

(h1)

0.4

(h1)

0.8

(h1)

1.2

(h1)

Yield (vol.%) 20.1 19.9 18.7 76.9 72.2 69.9

S & N analysis (wt.%)

S (ppm) 71 78 167 54 67 82

N (ppm) 14 19 141 8 51 226

H/C molar ratio 1.81 1.79 1.72 1.71 1.67 1.59Distillation range (C)

IBP 95 96 96 / / /

10% 122 121 129 / / /

50% / / / 275 275 273

90% / / / 343 340 342

FBP 286 290 279 360 358 365

Density (20C)

(gmL1)

0.8060 0.8067 0.8086 0.8863 0.8895 0.8940

RON 93.0 93.2 95.2 / / /

AKI 88.2 88.7 90.3 / / /

Cetane value / / / 56.2 56.0 53.6

Solidifying point (C) / / / +4.3 +5.1 +5.1

a Other experimental conditions:PH2 = 6 MPa,Thf=360C,Thc=380C and H2/oil

ratio = 1600.

Fig. 3. FT-IR spectra for (A) the coal tar; (B) the gasoline product and (C) the diesel

product. Experimental conditions: PH2 = 6 Mpa, Thf=360C, Thc=380C, LHSV =

0.4 h1, H2/oil ratio=1600.

3408 T. Kan et al./ Fuel 90 (2011) 34043409


6/6

sisted impregnation and temperature-programming. Clean liquid

fuels were obtained from middle-temperature coal tar via hydro-

genation in two-stage fixed beds filled with the laboratory made

catalysts. The effects of pressure and liquid hourly space velocity

on hydrogenation performance were investigated. Gasoline

(6180C), and diesel (180360C) fractions were separated from

the oil product and analyzed. The two-stage reacting system was

capable of removing nitrogen and sulfur from 1.69 and 0.98 wt.%in the feed to less than 10 ppm and 100 ppm, respectively in the

products. The results showed that the raw coal tar can be consid-

erably upgraded through catalytic hydroprocessing. More effective

catalysts and investigations are still required to produce gasoline

and diesel with lower sulfur content.

Acknowledgements

The authors are grateful to the National Natural Science Foun-

dation of China (No. 21006113) and National Basic Research Pro-

gram of China (973 Program No. 2009CB219900).

References

[1] Liu Z, Shi S, Li Y. Coal liquefaction technologies development in China andchallenges in chemical reaction engineering. Chem Eng Sci 2010;65:127.

[2] Cui H, Yang J, Liu Z, Bi J. Effects of remained catalysts and enriched coalminerals on devolatilization of residual chars from coal liquefaction. Fuel2002;81:152531.

[3] Yang J, Zhu J, Xu L, Liu Z, Li Y, Li B. Promotion of the ferrous sulfate catalysts bysulfur for hydrogenation of coal. Fuel 2002;81:14859.

[4] Zhang L, Yang J, Zhu J, Liu Z, Li B, Hu T, Dong B. Properties and liquefactionactivities of ferrous sulfate based catalyst impregnated on two Chinesebituminous coals. Fuel 2002;81:9518.

[5] Li C, Suzuki K. Resources, properties and utilization of tar. Resour Conserv Recy2010;54:90515.

[6] Vishwakarma SK, Sundaramurthy V, Dalai AK. Performances of CoW/c-Al2O3catalysts on hydrotreatment of light gas oil derived from Athabasca bitumen.Ind Eng Chem Res 2007;46:477886.

[7] Zhang XF, Zhang QM, Zhao AQ, Guan J, He DM, Hu HQ, Liang CH.Hydrogenation of naphthalene over nickel phosphide supported on silica forin the absence and presence of quinoline and its hydrogenated intermediates.

Energy Fuels 2010;24:3796803.[8] Liang CH, Zhao AQ, Zhang XF, Ma ZQ, Prins R. CoSi particles on silica support asa highly active and selective catalyst for naphthalene hydrogenation. ChemCommun 2009:20479.

[9] Huang TC, Kang BC. Naphthalene hydrogenation over Pt/Al2O3 catalyst in atrickle bed reactor. Ind Eng Chem Res 1995;34:234957.

[10] Nuzzi M, Marcandalli B. Hydrogenation of phenanthrene in the presence of Nicatalyst. Thermal dehydrogenation of hydrophenanthrenes and role ofindividual species in hydrogen transfers for coal liquefaction. Fuel ProcessTechnol 2003;80:3545.

[11] Wiser WH, Singh S, Qader SA, Hill GR. Catalytic hydrogenation of multiringaromatic coal tar constituents. Ind Eng Chem Prod Res Dev 1970;9:3507.

[12] Luan YZ, Zhang QM, He DM, Guan J, Liang CH. Hydrodenitrogenation ofquinoline and its intermediates over sulfided NiW/Al2O3 in the absence andpresence of H2S. Asia-Pacific J Chem Eng 2009;4:70410.

[13] Froment GF, Castaneda-Lopez LC, Marin-Rosas C. Kinetic modeling of thehydrotreatment of light cycle oil and heavy gas oil using the structuralcontributions approach. Catal Today 2008;130:44654.

[14] Kumar H, Froment GF. Mechanistic kinetic modeling of the hydrocracking of

complex feedstocks, such as vacuum gas oils. Ind Eng Chem Res2007;46:588197.

[15] Mapiour M, Sundaramurthy V, Dalai AK, Adjaye J. Effects of the operatingvariables on hydrotreating of heavy gas oil: experimental, modeling, andkinetic studies. Fuel 2010;89:253643.

[16] Mapiour M, Sundaramurthy V, Dalai AK, Adjaye J. Effects of hydrogen partialpressure on hydrotreating of heavy gas oil derived from oilsands bitumen:experimental and kinetics. Energy Fuels 2010;24:77284.

[17] Girgis MJ, Gates BC. Reactivities, reaction networks, and kinetics in highpressure catalytic hydroprocessing. Ind Eng Chem Res 1991;30:202158.

[18] Wailes PC. Upgrading of coal-derived products. Fuel 1982;61:103844.[19] Furimsky E. Selection of catalysts and reactors for hydroprocessing. Appl Catal

A 1998;171:177206.[20] Furimsky E. Catalysts for upgrading heavy petroleum feeds. Elsevier Science;

2007. p. 169.[21] Clough H. Gasoline production from coal tar oils. Ind Eng Chem

1957;49:6738.[22] Raje AP, Liaw SJ, Srinivasan R, Davis BH. Second row transition metal sulfides

for the hydrotreatment of coal-derived naphtha. I. Catalyst preparation,characterization and comparison of rate of simultaneous removal of totalsulfur, nitrogen and oxygen. Appl Catal A 1997;150:297318.

[23] Liaw SJ, Lin R, Raje A, Davis BH. Hydrotreatment of coal-derived naphtha.Properties of zeolite-supported Ru sulfide catalysts. Appl Catal A1997;151:42335.

[24] Pier M. Einiges uber hydrier und spaltkatalysatoren der ol-verarbeitung undkohle-verarbeitung. Zeitschrift Fur Elektrochemie 1949;53:291301.

[25] Dhas NA, Ekhtiarzadeh A, Suslick KS. Sonochemical preparation of supportedhydrodesulfurization catalysts. J Am Chem Soc 2001;123:8310.

[26] Gusta E, Sundaramurthy V, Dalai AK, Adjaye J. Hydrotreatin of heavy gas oilderived from Athabasca bitumen over CoMo/cAl2O3 catalyst prepared bysonochemical method. Top Catal 2006;37:147.

[27] Lee JJ, Heeyeon K, Sang HM. Preparation of highly loaded, dispersed MoS 2/Al2O3 catalysts for the deep desulphurization for dibenzothiophenes. ApplCatal B 2003;41:171.

[28] Mahajan D, Marshall CL, Castagnola N, Hanson JC. Sono synthesis andcharacterization of nano-phase molybdenum-based materials for catalytichydrodesulfurization. Appl Catal A 2004;258:83.

[29] Leckel D. Catalytic hydroprocessing of coal-derived gasification residues tofuel blending stocks: effect of reaction variables and catalyst onhydrodeoxygenation (HDO), hydrodenitrogenation (HDN), andhydrodesulfurization (HDS). Energy Fuels 2006;20:17616.

[30] Cocchetto TF, Satterfield CN. Thermodynamic equilibria of selectedheterocyclic nitrogen compounds with their hydrogenated derivatives. IndEng Chem Process Des Dev 1976;15:2727.

[31] Liaw SJ, Raje AP, Thomas GA, Davis BH. Second row transition metal sulfidesfor the hydrotreatment of coal derived naphtha. III. Removal of individualnitrogen compounds. Appl Catal A 1997;150:34364.

[32] Lauritsen JV, Bollinger MV, Lgsgaard E, Jacobsen KW, Nrskov JK, Clausen BS,Topse H, Besenbacher F. Atomic-scale insight into structure and morphology

changes of MoS2 nanoclusters in hydrotreating catalysts. J Catal2004;221:51022.

[33] Lauritsen JV, Nyberg M, Nrskov JK, Clausen BS, Topse H, Lgsgaard E,Besenbacher F. Hydrodesulfurization reaction pathways on MoS2 nanoclustersrevealed by scanning tunneling microscopy. J Catal 2004;224:94106.

[34] Besenbacher F, Brorson M, Clausen BS, Helveg S, Hinnemann B, Kibsgaard J,Lauritsen JV, Moses PG, Nrskov JK, Recent Topse H, TM S. DFT and HAADF-STEM studies of sulfide-based hydrotreating catalysts: Insight intomechanistic, structural and particle size effects. Catal Today 2008;130:8696.

[35] Temel B, Tuxen AK, Kibsgaard J, Topse NY, Hinnemann B, Knudsen KG,Topse H, Lauritsen JV, Besenbacher F. Atomic-scale insight into the originof pyridine inhibition of MoS2-based hydrotreating catalysts. J Catal2010;271:2809.

[36] Logadottir A, Moses PG, Hinnemann B, Topse NY, Topse H, Nrskov JK. Adensity functional study of inhibition of the HDS hydrogenation pathway bypyridine, benzene, and H2S on MoS2-based catalysts. Catal Today2006;111:4451.

[37] Li C, Suzuki K. Tar property, analysis, reforming mechanism and model forbiomass gasification an overview. Renew Sustain Energ Rev 2009;13:

594604.

T. Kan et al./ Fuel 90 (2011) 34043409 3409

Documents

Catalyst Efficacy