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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:csli@home.ipe.ac.cn(C. Li),sjzhang@home.ipe.ac.cn(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:csli@home.ipe.ac.cnmailto:sjzhang@home.ipe.ac.cnhttp://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:sjzhang@home.ipe.ac.cnmailto:csli@home.ipe.ac.cnhttp://dx.doi.org/10.1016/j.fuel.2011.06.0128/13/2019 Catalyst Efficacy
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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
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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
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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
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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
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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).
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