Hydrotreatment of light cycle oil over a dispersed MoS2
catalyst
Haiping Zhang, Hongfei Lin, Ying Zheng *
Department of Chemical Engineering, University of New Brunswick, 15
Dineen Drive, Fredericton, NB, E3B 5A3, Canada
*Ying Zheng, Corresponding author, [email protected], 1 (506) 447-3329
Abstract
Examination of the hydrotreatment of light cycle oil over a dispersed MoS2 catalyst was
conducted in a batch reactor at 375°C and 1500psi. Hydrodesulfurization, hydrodenitrogenation,
hydrogenation of aromatics, and hydrocracking activity were all analyzed. Diaromatics are more
reactive than monoaromatics. Different sulfur compounds have experimental rates of elimination
following the trend of BT>1MBT>> 2MBT>3MBT>4MBT>>DBT≈1MDBT≈2MDBT≈3MDBT.
BT and its derivatives are very reactive and easy to eliminate, but become harder to convert as
they gain methyl groups. DBTs are harder to eliminate than BTs, and don’t experience significant
changes in reactivity as they gain methyl groups. This difference indicates that steric hindrance is
more significant in supported catalysts than in unsupported catalysts. Different nitrogen
compounds have experimental rates of elimination following the trend of Anilines> Indoles>
Carbazoles.
Keywords: Kinetics; hydrotreatment; hydrodesulfurization; light cycle oil; dispersed MoS2.
1
1
Introduction
Light cycle oil (LCO) obtained from a fluid catalytic cracking unit (FCCU) is a blend to straight
run gas oil used for diesel production [1, 2]. An increasing demand for diesel fuels requires more
LCO to be added to the diesel pool [3]. However, LCO has a high density and contains large
amounts of sulfur, nitrogen, and aromatics [4] – its quality needs to be improved. Hydrotreating is
a common approach in upgrading LCO for diesel production.
Previous research has demonstrated that sulfur containing compounds in LCO include alkylsubstituted benzothiophenes and dibenzothiophenes, such as BT, MBT, DBT, MDBT, and 4,6DMDBT [5]. In the literature, model compounds are normally used for kinetics studies due to the
complexity of LCO [7, 8]. The hydrodesulfurization (HDS) reaction of the hard sulfur
compounds (DBT and its alkyl-substitutes) occurs mainly through two parallel routes: the
hydrogenation of one phenyl ring prior to hydrogenolysis (HYD) and the direct desulfurization of
C-S bonds (DDS) [9, 10]. Alkyl-substituted DBTs, especially ones with methyl groups at the 4
and 6 positions, have lower reaction rates compared to DBT. This is due to a strong steric
hindrance and electronic effect [11, 12]. Moreover, deep desulfurization is greatly inhibited in the
presence of nitrogen containing compounds [13, 14]. Nitrogen containing compounds have a
higher affinity for active sites and relatively lower reaction rates when compared to sulfur
containing compounds – they therefore take up active sites and stay there for long periods of time,
thereby reducing HDS rates. Similarly, aromatic compounds in LCO may also inhibit the HDS by
taking up hydrogenation active sites on the MoS2 catalysts [11, 15].
Catalysts play a key role in catalytic hydrodesulfurization. In the past decades, studies have
focused on conventional sulfided catalysts supported by γ-alumina [16, 17]. Al2O3 is widely
applied because of its stability, acidity, and high surface area [18]. However, it is reported that
Al2O3 supported Mo catalysts are not efficient in eliminating heteroaromatic sulfur containing
compounds such as DBTs [19]. Dispersed MoS2 own several advantages over the supported
MoS2. They show good performance in terms of activity and thermo stability, compared to the
traditional supported sulfide catalysts. One of such catalysts, NEBULA (brand name), has been
successfully applied in refineries, exhibiting 3 to 4 times higher activity than conventional
supported catalysts [20]. such as higher activity and lower steric hindrance. the bulk sulfide-based
Mo catalysts Farag et al. pointed out that dispersed MoS2 desulfurizes DBTs primarily over HYD
pathway and the supported MoS2 desulfurizes DBTs via both HYD and DDS pathways [21, 22].
Liu and Ng reported that dispersed MoS2 were effective in hydrodesulfurization of hard sulfur
such as DMDBT [23]. Jansen et al. studied recycling of the dispersed catalyst in treating heavy
hydrocarbons [24].
In this work, light cycle oil was hydrotreated by an unsupported dispersed nano-catalyst MoS2,
which was synthesized through a reported novel hydrothermal method [25]. The feed oil and
liquid products were extensively analyzed. The hydrodesulfurization (HDS) and
hydrodenitrogenation (HDN) activities were evaluated by analyzing sulfur and nitrogen amounts
in the original LCO and hydrotreated products. The HDS and HDN kinetics were demonstrated
by analyzing the sulfur and nitrogen compound compositions. Hydrogenation ability was
demonstrated by evaluating the variation of aromatic compounds during the reaction. A
2
hydrocracking reaction was indicated at by the distribution of boiling points and liquid densities
in the original and hydrotreated products.
2
Experimental
2.1 Catalyst synthesis and characterization
A series of molybdenum sulfided catalysts were synthesized through the hydrothermal method
[25] using MoO3 (STEM Scientific) and Na2S·9H2O (Fisher Scientific) as precursors. MoO3 and
Na2S·9H2O were first dissolved in deionized water and then HCl was slowly added to the solution.
The mixture was placed into an autoclave reactor for 2h at 320˚C and 500rpm. The resultant
black solid was washed with deionized water and ethanol.
The synthesized catalysts were identified by X-ray diffraction (XRD) pattern, which were
recorded on a diffractometer using CuKα radiation with a 2θ range of 5-85° and scan speed of
1°/min. The morphology of catalysts was also measured using a transmission electron microscope
(JEOL 2011 STEM, JEOL Ltd., Tokyo, Japan). The length and the number of layers of the MoS2
crystal were analyzed using imaging analysis software. The specific surface area of the catalyst
powder was calculated using the Brunauer-Emmett-Teller (BET) method, based on the nitrogen
adsorption-desorption isotherm measured by an Autosorb-1 (Quantachrome Instruments). The
total pore volume was calculated from the volume of nitrogen adsorbed at the relative pressure
p/p0 0.995. Pore size distribution was analyzed from the isotherms, by the Barrett-Joyner-Halenda
(BJH) method.
2.2 Hydrotreating process
A 1L batch reactor from Autoclave Engineering was employed in this experiment. Many trials
were conducted and a typical procedure is shown below. Light cycle oil (LCO) containing 1.45%
sulfur and 159ppm nitrogen was used as feedstock. The specifications of LCO are listed in Table
1. Catalysts that had been filtered through 200 meshes were added into the batch reactor. After
the reactor was heated to 375ºC, 120g of LCO was introduced with different catalyst-to-oil
weight ratios (COR). Samples were taken during the reaction. The effect of sampling is assumed
to be negligible due to the small sample amounts (<1.0 gram per sample). Hydrodesulfurization
(HDS) and hydrodenitrogenation (HDN) took place at 375ºC under 1500psi hydrogen pressure
and at a stirring speed of 1000rpm. The mass transfer resistance was ignored, due to the nano size
of the catalyst [26].
2.3 Product analysis
The sulfur and nitrogen amounts in the original LCO and hydrotreated products were determined
using a Sulfur/Nitrogen analyzer (9000 series, Antek Instruments Inc). The hydrodesulfurization
conversion and hydrodenitrogenation conversion (xHDS and xHDN) is the ratio of removed sulfur
and nitrogen to their respective amounts in the feed. A first-order reaction was assumed for the
calculation of the HDS and HDN rate constant k.
3
𝑥𝐻𝐷𝑆 =
𝑆𝐹𝑒𝑒𝑑 −𝑆𝑃𝑟𝑜𝑑𝑢𝑐𝑡
𝑆𝐹𝑒𝑒𝑑
× 100%
Equation 1
𝑥𝐻𝐷𝑁 =
𝑁𝐹𝑒𝑒𝑑 −𝑁𝑃𝑟𝑜𝑑𝑢𝑐𝑡
𝑁𝐹𝑒𝑒𝑑
× 100%
Equation 2
The distribution of sulfur compounds in the feed and products was analyzed using a gas
chromatograph (Varian 450) equipped with a non-polar VF-1ms capillary column (15m x
0.25mm x 0.25μm, max temperature: 325°C) and a pulsed flame photometric detector (PFPD).
Benzothiophene (BT), dibenzothiophene (DBT), and 4, 6-dimethyldibenzothiophene (4, 6DMDBT) were used to represent easy and hard sulfur compounds. The distribution of nitrogen
compounds in the feed and products was analyzed using a gas chromatograph (GC-950, Shanghai
Haixin Chromatographic Instrument Co. LTD) equipped with a nitrogen phosphorus detector
(NPD). Anilines, indole, quinoline, tetrahydroquinoline, and carbazole were used to represent the
different nitrogen compounds. The parameter setup followed the literature [27]. The column was
heated up at 4°C/min from 40°C to 265°C. The distribution of aromatics in the collected samples
was determined by high performance liquid chromatography (HPLC, Agilent 1200 series)
according to ASTM 6591. Simulated distillation of the products was carried out using Shimadzu
GC-2010 according to ASTM-2887. The density of the oil was measured by portable density
meter (DMA 35N, Anton Paar GmbH, Graz, Austria) following ASTM 4052.
3
Results and discussion
3.1 Catalyst characterization
Dispersed MoS2 crystallines are successfully synthesized. It is seen from the XRD spectra (Fig. 1).
Characteristic MoS2 diffraction peaks are observed attributing to the planes (002), (100), (103),
(110), (105), and (201), respectively. The broad peaks indicate a nano crystalline structure, which
is verified from TEM images. Fig. 2 shows MoS2 consists of layered sheets forming S–Mo–S
sandwiches. In the pure compounds the sheets are stacked and held together by van der Waals
forces. The synthesized MoS2 has a highly dispersed dendritic morphology and a layered
nanocrystal with an average length of 17.43nm and width of 2.93nm (Table 2). Most of the
crystals shown are curved and associated with each other, leading to a high BET surface area of
236.3m2/g and a high pore volume of 2.276 cm3/g. The isotherm curve shows a type V shape, and
the hysteresis loop between adsorption and desorption isotherms is associated with mesoporosity
(Fig. 3a). Pore size distribution was determined by the isotherm curve by BJH analysis (Fig. 3b).
A bimodal distribution was observed with a sharp peak centered at 2.46nm with a small shoulder
of 3.84nm and a broad peak at about 12nm. The spent catalyst were also characterized and found
all the properties are similar to the fresh catalyst.
3.2 Hydrodesulfurization activity
The graph of sulfur conversion versus hydrotreatment time is shown in Fig. 4. Three catalyst-tooil (COR) ratios were used to investigate the effect of catalyst amounts on HDS performance. At
a very low ratio (e.g. 1:800), the HDS rate increases gradually with time. Addition of more
catalysts results in a sharp increase in sulfur conversion during the initial reaction. When the COR
4
reaches 1:100, the conversion rate increases dramatically during the first half hour, followed by a
relatively slow increase from 0.5 hours to approximately 2 hours. From 2 hours to 8 hours, the
conversion rate only increases very slowly (by approximately 10%). A higher COR is related to a
higher initial reaction speed. Sulfur conversion reaches almost 60% within the first half hour
when the COR is at 1:100, whereas the amounts of sulfur conversion for CORs 1:200 and 1:800
during the same time period are 30% and 15%, respectively. This indicates that the use of more
catalysts can significantly increase the removal rate of easy sulfurs. Between 2 hours and 8 hours,
the sulfur conversion rates between all CORs remain similar. This suggests that different CORs
exhibit similar removal rates for hard sulfurs. At the end of the reaction (8 hours), the higher
COR samples contain lower amounts of sulfur. This may be explained by the fact that when more
catalysts are involved, the time required for the depletion of easy sulfur is reduced, and therefore
the catalyst gains more time for the removal of hard sulfurs.
Several different sulfur species were identified in the LCO (Fig. 5), including benzothiophene
(BT), methyl- benzothiophene (1MBT-4MBT), dibenzothiophene (DBT), and methyldibenzothiophene (1MDBT-3MDBT). At hour 2 of the reaction, easy sulfurs such as BT, 1MBT4MBT were almost removed, whereas hard sulfurs remained largely unreacted. This is consistent
with the observation that only easy sulfurs are quickly removed within the first 2 hours. At the
end of the reaction, no easy sulfurs were detected in the final products. The amounts of hard
sulfurs were also greatly reduced but not totally removed, indicating that hard sulfurs require a
significantly longer time to react compared to easy sulfurs. This is probably because hard sulfurs
like 1-3MDBT have an additional aromatic ring, which greatly increases steric hindrance and
decreases contact efficiency between the substance and the active sites on catalysts. This
observation is agreed upon with other researchers.
The amounts of main sulfur-containing compounds vary with reaction time and are shown in Fig.
6; the calculated rate constants are listed in Table 3. The compounds are catalogued into two
groups: easy sulfurs (Fig. 6a) and hard sulfurs (Fig. 6b). In Fig 6a, BT and 1MBT show the
highest reaction rates, and are completely removed within the first 2 hours. Compounds from
2MBT to 4MBT show slightly lower reaction speeds, but more than 90% of these substances are
still converted at the 2nd hour. The reaction becomes more difficult due to additional alkyls on
the aromatic ring. Computational study [28] showed that charges of the methyl-substituted sulfurcontaining compounds become more concentrated on the sulfur atom. Hydrogen needs to use
methyl groups as bridge to transfer to sulfur atom and the sulfur atoms are more refractory in the
hydrodesulfurization process. This give a possible electronic explanation to the experimentally
observed. In Fig. 6b, all the compounds exhibit similar reaction rates, indicating that the steric
effect is not significant among these compounds. Compared easy sulfurs that showed a decreasing
reaction rates against reaction time, hard sulfurs remains a similar conversion rate throughout.
This contrast exists probably due to the fact that easy sulfurs can utilize more active sites on
catalysts than hard sulfurs can. With stronger steric effects, hard sulfurs can only be absorbed on
certain sites, and so their reaction rates are determined by the amount of active sites specific for
hard sulfurs on the catalysts.
5
3.3 Hydrodenitrogenation activity
The LCO feedstock used in this study contains small amounts of nitrogen compounds, which are
categorized into 3 species: anilines, indoles and carbazoles. The nitrogen components in the feed
and product were determined using GC-NPD (Fig. 7). In LCO feedstock, the content of indole is
significantly higher than its alkyl derivatives. For carbazoles, the highest peak refers to C1
carbazole. Fig. 7 shows that all anilines and the majority of indoles and carbazoles were removed
within 6 hours of hydrotreatment. The unreacted nitrogen containing compounds were mainly C4
indoles and C1-C2 carbazoles. The nitrogen distribution in the feed and in the products at hours 2
and 6 are listed in Table 4. In the reaction, anilines were the easiest nitrogen compound in LCO
and were quickly removed within the first 2 hours. Indoles were harder to remove, the indole
concentration only dropping from 73.73 ppm to 20.2 ppm in the first 2 hours. Carbazoles were
the hardest nitrogen compounds to remove, only reducing by about 50% in the first 2 hours. The
dynamics of different nitrogen types were simulated by pseudo-first-order and their rate constants
are listed in Table 5. Only indole and carbazole are provided since anilines were not detectable
after 2 hours of reaction.
3.4 Hydrogenation and hydrocracking activities
The amounts of aliphatic and aromatic hydrocarbons over time during hydrotreatment are shown
in Fig. 8. The content of aliphatic hydrocarbons was almost unchanged, indicating that the
conversion from aromatic to aliphatic hydrocarbons was insignificant. However, considerable
diaromatics were reduced to monoaromatics: the percent fraction of diaromatics decreased from
52.3% to 10.3% while the percent fraction of monoaromatics increased from 12.9% to 59.6%.
Polycyclic aromatics were very hard to eliminate.
The hydrocracking activity was evaluated by simulated distillation (Fig. 9). During the reaction,
the fraction of heavy components (boiling points > 250 °C) gradually decreased and the fraction
of relatively lighter components (boiling points of 200-250 °C) increased significantly. This
indicates that a hydrocracking reaction occurred in the heavier components of the LCO. It was
noticed that the total fraction of components with boiling points above 300 °C barely changed
within the first 6 hours. This indicates that the hydrocracking reaction mostly only converted the
250-300 °C fraction to the 200-250 °C fraction during the first several hours. However, it was
noticed that hydrocracking on components with boiling points greater than 300 °C eventually
happened during hydrotreatment. This was evidenced by a decrease in the >300 °C fraction after
8 hours of reaction.
Conclusions
Light cycle oil is a complex middle distillate, containing different kinds of sulfur, nitrogen and
aromatic compounds. Hydrotreatment of this complex feedstock using a dispersed MoS2 catalyst
was carried out in a batch reactor and conclusions were drawn through the extensive analysis of
hydrotreated products. The reactivity of different sulfur compounds in the LCO followed the
trend BT>1MBT>>2MBT>3MBT>4MBT>> DBT≈1MDBT≈2MDBT≈3MDBT. The rate of
elimination of nitrogen compounds in the LCO followed the trend of Anilines > Indoles >
Carbazoles. Hydrogenation mainly occurred on bicyclic aromatics which were reduced to
6
monocyclic compounds; monocyclic and polycyclic aromatics were barely hydrogenated. This
phenomenon confirms the weak hydrogenation ability of the unsupported catalyst. Hydrocracking
activity was revealed by the distribution of boiling points and the variation of liquid densities in
the feed and final products.
Acknowledgements
The authors gratefully acknowledge the financial assistance from Canada Research Chairs
program, Natural Sciences and Engineering Research Council of Canada and Canada Foundation
for Innovation.
7
Table 1 Properties and composition of light cycle oil
Properties
Density (g/ml, 30°C)
Sulfur content (w.t. %)
Nitrogen (ppmw)
0.9641
1.45
159.2
Chemical composition (w.t. %)
Saturates
Monoaromatics
Diaromatics
Polyaromatics
22.61
12.89
52.35
12.15
Boiling points (°C)
Initial boiling point (IBP)
10%
20%
30%
40%
50%
60%
70%
80%
90%
Final boiling point (FBP)
113.3
227.0
237.5
254.9
258.7
273.5
283.4
293.8
307.3
328.4
376.4
Table 2 Specifications of unsupported MoS2 catalysts
Properties
Average Slab length (nm)
17.43
Average Slab width (nm)
2.93
BET surface area (m2/g)
236.3
Total pore volume (cm3/g)
2.276
Average pore size (nm)
9.36
Table 3 Reaction rate constant for different sulfur components
Components
kHDS (x10-4 s-1 g cata -1)
BT
20.65
1MBT
14.15
2MBT
5.14
3MBT
4.98
4MBT
4.54
DBT
0.65
1MDBT
0.63
2MDBT
0.65
3MDBT
0.65
8
Table 4 Nitrogen distribution in feed and hydrotreated products
Hydrotreating time N in Alilines
N in Indoles
N in carbazoles
(h)
(ppm)
(ppm)
(ppm)
0 (LCO2)
10.3
76.73
67.2
2
0
20.2
34.4
6
0
6.9
9.8
Table 5 Reaction rate constant for different nitrogen type
Components
kHDS (x10-4 s-1 g cata -1)
Indole types
1.60
Carbazole types
1.29
9
Total N
(ppm)
159.2
54.6
16.7
100
110
Intensity
103
105
002
10
20
30
40
50
2 ()
201
60
70
Fig. 1 XRD spectrum of dispersed MoS2
Fig. 2 TEM images of dispersed MoS2
10
80
a
3
Adsorbed volume (cm /g)
1600
1200
800
400
0
0.0
0.2
0.4
0.6
Relative pressure P/Po
0.8
1.0
b
0.02
3
Dv(d) [cm /nm/g]
0.03
0.01
0.00
0
5
10
15
20
Diameter (nm)
25
30
Fig. 3 Isotherm curve and pore size distribution of dispersed MoS2 by BJH (adsorption)
11
100
HDS conversion (%)
80
60
COR 1:100
COR 1:200
COR 1:800
40
20
0
0
1
2
3
4
5
Hydrotreating time (h)
6
7
8
Fig. 4 HDS conversion over dispersed MoS2 at different catalyst-to-oil ratios (COR, w.t.)
12
LCO
Hydrotreated for 2h
Hydrotreated for 8h
4
6
8
10
12
14
Retention time (min)
16
18
20
Fig. 5 Major sulfur compounds composition of LCO and hydrotreated products (GC-PFPD),
COR=1:200
13
a
100
80
Conversion (%)
b
100
DBT
1MDBT
2MDBT
3MDBT
DBT-MDBT
80
BT
1MBT
2MBT
3MBT
4MBT
BT-MBT
60
40
60
40
20
20
0
0
0
1
2 3 4 5 6 7
Hydrotreating time (h)
8
0
1
2 3 4 5 6 7
Hydrotreating time (h)
Fig. 6 The conversion of individual sulfur compounds (COR 1:200)
14
8
LCO
Indoles
H
N
Carbazoles
H
N
H
N
Anilines
C1
H
N
H
N
H
N
C4
C1
C2 H
N
H
N
H
N
C3
C3
C2
H
N
Intensity
C4
Hydrotreated for 6h
Indoles
15
20
25
30
35
Carbazoles
40
45
50
Retention time (min)
Fig. 7 Major nitrogen compounds composition of LCO and hydrotreated products (GC-NPD)
15
60
50
Aliphatic
Monocyclic
Bicyclic
Polycyclic
Fraction (%)
40
30
20
10
0
0
1
2
3
4
5
Hydrotreating time (h)
6
7
Fig. 8 Hydrogenation along with hydrotreating time (COR 1:200)
16
8
0-100 °C
250-300 °C
100-150 °C
300-350 °C
150-200 °C
350-400 °C
200-250 °C
100
Fraction (%)
80
60
40
20
0
Feed
0.33
1
2
4
6
8
Hydrotreating time (h)
Fig. 9 Boiling point distribution of LCO and hydrotreated products (COR 1:200)
0.97
3
Density (g/cm )
0.96
0.95
0.94
0.93
0
1
2
3
4
5
Hydrotreating time (h)
6
7
8
Fig. 10 Variation of density of the product with the hydrotreating time (COR 1:200)
17
References
[1] Đukanović, Z., Glišić, S.B., Čobanin, V.J., Nićiforović, M., Georgiou, C.A., Orlović, A.M.,
2013. Hydrotreating of straight-run gas oil blended with FCC naphtha and light cycle oil, FUEL
PROCESSING TECHNOLOGY, 106, 160-165.
[2] Ancheyta-Juárez, J., Aguilar-Rodrıǵ uez, E., Salazar-Sotelo, D., Betancourt-Rivera, G., LeivaNuncio, M., 1999. Hydrotreating of straight run gas oil–light cycle oil blends, APPLIED
CATALYSIS A: GENERAL, 180, 195-205.
[3] Liu, Z., Zheng, Y., Wang, W., Zhang, Q., Jia, L., 2008. Simulation of hydrotreating of light
cycle oil with a system dynamics model, APPLIED CATALYSIS A: GENERAL, 339, 209-220.
[4] Nylén, U., Delgado, J.F., Järås, S., Boutonnet, M., 2004. Characterization of alkylated
aromatic sulphur compounds in light cycle oil from hydrotreated vacuum gas oil using GC-SCD,
FUEL PROCESSING TECHNOLOGY, 86, 223-234.
[5] Yang, H., Chen, J., Fairbridge, C., Briker, Y., Zhu, Y.J., Ring, Z., 2004. Inhibition of nitrogen
compounds on the hydrodesulfurization of substituted dibenzothiophenes in light cycle oil, FUEL
PROCESSING TECHNOLOGY, 85, 1415-1429.
[6] Shafi, R., Hutchings, G.J., 2000. Hydrodesulfurization of hindered dibenzothiophenes: an
overview, CATALYSIS TODAY, 59, 423-442.
[7] Saih, Y., Segawa, K., 2003. Ultradeep hydrodesulfurization of dibenzothiophene (DBT)
derivatives over Mo-sulfide catalysts supported on TiO2-coated alumina composite,
CATALYSIS SURVEYS FROM ASIA, 7, 235-249.
[8] Vradman, L., Landau, M.V., Herskowitz, M., 1999. Deep desulfurization of diesel fuels:
kinetic modeling of model compounds in trickle-bed, CATALYSIS TODAY, 48, 41-48.
[9] Farag, H., Mochida, I., 2012. A comparative kinetic study on ultra-deep hydrodesulfurization
of pre-treated gas oil over nanosized MoS2, CoMo-sulfide, and commercial CoMo/Al2O3
catalysts, JOURNAL OF COLLOID AND INTERFACE SCIENCE, 372, 121-129.
[10] Landau, M.V., 1997. Deep hydrotreating of middle distillates from crude and shale oils,
CATALYSIS TODAY, 36, 393-429.
[11] Song, T., Zhang, Z., Chen, J., Ring, Z., Yang, H., Zheng, Y., 2006, Effect of aromatics on
deep hydrodesulfurization of dibenzothiophene and 4,6-dimethyldibenzothiophene over
NiMo/Al2O3 catalyst, ENERGY AND FUELS, 20, 2344-2349.
[12] Gates, B.C., Topsøe, H., 1997. Reactivities in deep catalytic hydrodesulfurization:
challenges, opportunities, and the importance of 4-methyldibenzothiophene and 4,6dimethyldibenzothiophene, Polyhedron, 16, 3213-3217.
18
[13] Yang, H., Chen, J.W., Briker, Y., Szynkarczuk, R., Ring, Z., 2005. Effect of nitrogen
removal from light cycle oil on the hydrodesulphurization of dibenzothiophene, 4methyldibenzothiophene and 4,6-dimethyldibenzothiophene, CATALYSIS TODAY, 109, 16-23.
[14] Egorova, M., Prins, R., 2004. Competitive hydrodesulfurization of 4,6dimethyldibenzothiophene, hydrodenitrogenation of 2-methylpyridine, and hydrogenation of
naphthalene over sulfided NiMo/gamma-Al2O3, JOURNAL OF CATALYSIS, 224, 278-287.
[15] Koltai, T., Macaud, M., Guevara, A., Schulz, E., Lemaire, M., Bacaud, R., Vrinat, M., 2002,
Comparative inhibiting effect of polycondensed aromatics and nitrogen compounds on the
hydrodesulfurization of alkyldibenzothiophenes, Applied Catalysis a-General, 231, 253-261.
[16] Yao, S., Zheng, Y., Ding, L., Ng, S., Yang, H., 2012. Co-promotion of fluorine and boron on
NiMo/Al2O3 for hydrotreating light cycle oil, Catalysis Science & Technology, 2, 1925-1932.
[17] Isoda, T., Nagao, S., Ma, X., Korai, Y., Mochida, I. 1997. Catalytic activities of NiMo and
CoMoAl2O3 of variable Ni and Co contents for the hydrodesulfurization of 4,6dimethyldibenzothiophene in the presence of naphthalene, APPLIED CATALYSIS A:
GENERAL, 150, 1-11.
[18] Azizi, N., Ali, S.A., Alhooshani, K., Kim, T., Lee, Y., Park, J.I., Miyawaki, J., Yoon, S.H.,
Mochida, I., 2013. Hydrotreating of light cycle oil over NiMo and CoMo catalysts with different
supports, FUEL PROCESSING TECHNOLOGY, 109, 172-178.
[19] Yoosuk, B., Song, C., Kim, J.H., Ngamcharussrivichai, C., Prasassarakich, P., 2010. Effects
of preparation conditions in hydrothermal synthesis of highly active unsupported NiMo sulfide
catalysts for simultaneous hydrodesulfurization of dibenzothiophene and 4,6dimethyldibenzothiophene, CATALYSIS TODAY, 149, 52-61.
[20] Eijsbouts, S., Mayo, S.W., Fujita, K., 2007, A Unsupported transition metal sulfide catalysts:
From fundamentals to industrial application, Appl. Catal., 322, 58.
[21] Farag, H., Sakanishi, K., Kouzu, M., Matsumura, A., Sugimoto, Y., Saito, I., 2003.
Investigation of the influence of H2S on hydrodesulfurization of dibenzothiophene over a bulk
MoS2 catalyst, INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH, 42, 306-310.
[22] Farag, H., Sakanishi, K., 2004. Investigation of 4,6-dimethyldibenzothiophene
hydrodesulfurization over a highly active bulk MoS2 catalyst, JOURNAL OF CATALYSIS, 225,
531-535.
[23] Liu, K., Ng, F., 2010, Effect of the nitrogen heterocyclic compounds on hydrodesulfurization
using in situ hydrogen and a dispersed Mo catalyst, Catalysis Today, 149, 28-34.
[24] Jansen, T., Guerry, D., Gotteland, D., Bacaud, R., Lacroix, M., Ropars, M., Lorentz, C.,
Geantet, C., TayakoutFayolle, M., 2014, Characterization of a continuous microscale
pilot unit for petroleum residue hydroconversion with dispersed catalysts: Hydrodynamics and
performances in once through and recycling mode, Chemical Engineering Journal, 253, 493-501.
19
[25] Zhang, H., Lin, H., Zheng, Y., Hu, Y.F., MacLennan, A., 2015, Understanding of the effect
of synthesis temperature on the crystallization and activity of nanoMoS2 catalyst, Applied
Catalysis B: Environmental 165, 537-546.
[26] Snare, M., Kubickova, I., Maki-Arvela, P., Eranen, K., Warna, J., Murzin, D.Y., 2007.
Production of diesel fuel from renewable feeds: Kinetics of ethyl stearate decarboxylation,
CHEMICAL ENGINEERING JOURNAL, 134, 29-34.
[27] Vassilaros, D.L., Kong, R.C., Later, D.W., Lee, M.L., 1982. Linear Retention Index System
for Polycylic Aromatic-compounds - Critical-Evaluation and additional Indexes, JOURNAL OF
CHROMATOGRAPHY, 252, 1-20.
[28] García-Cruz, I., Valencia, D., Klimova T., Oviedo-Roa, R., Manuel Martínez-Magadán, J.,
Gómez-Balderas R., Illas F., 2008, Proton affinity of S-containing aromatic compounds:
Implications for crude oil hydrodesulfurization, JOURNAL OF MOLECULAR CATALYSIS A:
CHEMICAL 281, 79–84.
20