Hydrodesulfurization Of Dibenzothiophene Research Articles

V-Containing Heteropoly Acids with Keggin Structure as Precursors of Sulfide Catalysts: Regularities of the Convertion of Dibenzothiophene and Naphthalene on Nonpromoted Mo–V Catalysts

Mixed PMoV heteropoly acids with Keggin structures H3+xPMo12–xVxO40 (x = 1–6) and modified sulfide catalysts on their basis were synthesized, their physicochemical characteristics were determined, and their performance in the reactions of hydrodesulfurization (HDS) of dibenzothiophene (DBT) and hydrogenation of naphthalene was evaluated. Modification of the Mo-containing catalysts with vanadium by impregnation with a solution of mixed heteropoly acids was found to enhance their catalytic activity in the studied reactions, as well as to increase the selectivity for the direct hydrodesulfurization route of the DBT HDS reaction.

Insight into effects of SO42- species on hydrodesulfurization of dibenzothiophene over an Fe-based bulk catalyst

The electron-rich Fe-based bulk catalysts are developed to promote the hydrodesulfurization (HDS) performance of dibenzothiophene (DBT). In this study, the Fe-Ti bulk catalyst was modified by the SO42- species to investigate the dispersibility, acidity, electron effect, and isolation effect impacting on HDS performance for DBT. Besides, as sulfidation degree (SD) improves, more the coordinately unsaturated sites (CUSs) will be available for the DBT molecules to be adsorbed and desulfurized that is conducive to the improvement of HDS performance for DBT over Fe-based bulk catalysts. Eventually, compared with Fe-Ti bulk catalyst, the HDS rate of DBT has a remarkable increase from 7.8% to 29.9%, 41.5% to 65.0%, and 70.2% to 90.5% under the reaction temperature with 300, 320, and 340 °C upon the introduction of the SO42- species for 0.3-SO42-/Fe-Ti catalyst, respectively. On the one hand, the Ti species can improve the conversion of electrons to Fe species that form electron-rich Fe-based catalysts, resulting in the improvement of the Fe-based bulk catalysts activity. On the other hand, the addition of SO42- species not only promote the SD by forming the Fe(III)-S and Fe1‐xS species but also strengthen the electron effect between Ti and Fe species, which is conducive to the improvement of HDS performance for DBT. In addition, the SO42- species also worked as an “isolate agent”, and can promote increasing the SD for this series of Fe-based bulk catalysts to improve the HDS rate of DBT. Thus, exploring the impact of SO42- species on the HDS performance of Fe-based catalysts is a promising direction for the design and development of environmentally friendly and economical low-cost HDS catalysts in the field of fossil fuel processing.

Non-metal doping Ni@C as highly efficient and stable hydrodesulfurization catalysts for clean liquid fuels

The development of highly efficient non-sulfide hydrodesulfurization (HDS) catalyst is still an extremely urgent and challenging matter for the ultra-deep HDS of crude oils. Based on the strategy of non-metal doping and incorporation of carbon, Ni2P@C, Ni2Si@C, and NiS2@C catalysts are successfully prepared through temperature-programmed route using MOF-derived Ni@C as precursor and investigated on the HDS of dibenzothiophene. The Ni2P@C sample has the highest HDS performance and the rate constant is 3.890 min−1, which corresponds to a 6-fold enhancement of that over Ni@C catalyst. While the Ni2Si@C catalyst corresponds to a 1.3-fold enhancement of that over Ni@C catalyst. The predictable result for the NiS2@C catalyst is very low HDS activity. There is a charge transfer between Ni and P or Si, which promotes the adsorption and reaction of dibenzothiophene. Moreover, the Ni2P@C catalyst shows outstanding stability during the long-term reaction after an 80 h. These results indicate that the non-metal doping and incorporation of carbon may be a powerful approach to improve the catalytic activity and improve the durability of catalyst for clean liquid fuels.

Hydrodesulfurization of dibenzothiophene and 4,6-dimethyldibenzothiophene over NiMo supported on yolk-shell silica catalysts with adjustable shell thickness and yolk size

Mesoporous yolk-shell silica spheres with different shell thicknesses and yolk sizes (YxSy) were synthesized by incubating mesostructured silica nanospheres with water. Al-modified YxSy-supported NiMo catalysts were prepared and applied to hydrodesulfurization (HDS) of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT). The shell thickness and yolk size have a large effect on the HDS activities. Among the as-made catalysts, NiMo/Al-Y30S13 catalyst with relatively low shell thickness (13 nm), yolk size (30 nm) and proper structural stability exhibit the highest activities for HDS of DBT and 4,6-DMDBT at the weight time of 1.39–13.76 g min mol−1, of which its DBT conversion at 1.39 g min mol−1 (50.4%) is 1.5 times as that of the reference NiMo/Al2O3 (33.6%), four times as that of NiMo/Al-Y83S28 (12.3%) and what’s more, the HDS conversion of Al-Y30S13 could reach 99.5% at 13.76 g min mol−1 (about 2.5 ppm S remained). Its 4,6-DMDBT conversion at 1.39 g min mol−1 (27.1%) is almost 2 times as that over NiMo/Al2O3 (13.8%), and 2.7 times as that over NiMo/Al-Y83S28 (9.9%). Additionally, the 95.7% HDS conversion (about 16.6 ppm S remained) of Al-Y30S13 could be obtained at 13.76 g min mol−1. The good HDS performance of the NiMo/Al-Y30S13 catalyst could be derived from the synergistic effect of moderate shell thickness and relatively small yolk size, proper structural stability, appropriate acidity, moderate metal-support interaction (MSI), suitable dispersion and desirable stacking morphology of the Ni and Mo species. DBT HDS over the NiMo/Al-Y30S13 catalyst shows the lowest direct desulfurization (DDS)/hydrodesulfurization (HYD) ratio (2.70), demonstrating that the increase of HYD proportion could improve the ability of ultra-deep desulfurization of catalysts. 4,6-DMDBT HDS over the NiMo/Al-Y30S13 catalyst shows the highest selectivity of isomerization (ISO) route (69%), illustrating that the ISO route is the dominant pathway. Furthermore, the mechanisms of DBT and 4,6-DMDBT HDS are proposed over NiMo/Al-YxSy materials.

Molybdenum boron based catalysts loaded on MnO alumina support for hydrodesulfurization of dibenzothiophene

The influence of boron on the activity of a hydrodesulfurization, HDS, catalyst was evaluated for the cleaner production of fuel. Thus, mixed oxides of γ-alumina and manganese oxide MnO were synthesized as a support and then loaded with molybdenum -copper, Mo-Cu, which work as an active phase and promoter. Different contents of boron were added to the synthesized catalysts to form AlMnO/MoCuB 0% (MAB 0), AlMnO/MoCuB 1% (MAB 1), AlMnO/MoCuB 2% (MAB 2) and AlMnO/MoCuB 5% (MAB 5). The textural properties of the materials were improved after the addition of boron from 164 m2/g of the control catalyst to 225, 258 and 265 m2/g for MAB (1), MAB (2) and MAB (5). X-ray diffraction (XRD) and Fourier transform infrared (FTIR) were utilized for structural characterization. X-ray photoelectron spectroscopy (XPS) was used to attain data on the chemical states and binding energies of the catalysts. A thermogravimetric analyzer (TGA) was utilized to assess the thermal stability of the catalysts. The catalytic activity was tested in a batch reactor system for the HDS of dibenzothiophene (DBT), under the following reaction parameters: T of 300 °C, hydrogen pressure of 55 bar and 6 h reaction time. After boron addition, it became 98% (MAB 5) compared to 87% of the MAB0 control catalyst and that clarified the role of boron in enhancing the catalyst performance.

Insight into metal-support interactions from the hydrodesulfurization of dibenzothiophene over Pd catalysts supported on UiO-66 and its amino-functionalized analogues

The hydrodesulfurization (HDS) of dibenzothiophene (DBT) was studied over a series of Pd catalysts supported on Zr-based metal-organic frameworks, UiO-66 and its amino-functionalized analogues (UiO-66-xNH2, where x represents the molar ratio of 2-amino-1,4-benzenedicarboxylic acid/1,4-benzenedicarboxylic acid) to gain an insight into metal-support interactions. Pd/UiO-66 behaved better than a Pd/γ-Al2O3 catalyst and a Pd/MCM-41 catalyst. The presence of amino groups showed minor negative influence on the conversion of DBT but significantly affected the activities and selectivities of different reaction pathways. With the increase in the content of amino groups, the direct desulfurization (DDS) pathway activity of the Pd/UiO-66-xNH2 catalysts increased, while their hydrogenation pathway activity decreased. This provides an approach for the regulation of the pathway selectivities of Pd HDS catalysts. Based on kinetic analysis and characterization results, we propose that the amino groups affect the HDS performance of Pd/UiO-66 mainly by affecting the adsorption of reacting molecules on metal particles.

Mesoporous Gamma‐Alumina‐Supported Mo Catalysts: Effect of Calcination Temperature

AbstractMesoporous γ‐Al2O3‐supported Mo oxides precursors were prepared by one‐step hydrolysis method without organic template at different calcination temperatures (MoOx/γ‐MA‐T) from 400 to 700 °C. Then MoS2 catalysts (MoS2/γ‐MA‐T) were obtained from the precursors through in‐situ sulfurization and applied for hydrodesulfurization (HDS) of dibenzothiophene (DBT). Effects of precursors calcination temperature on physicochemical properties and catalytic performances of catalysts were systematically investigated. With the increase of calcination temperature, the strength of metal‐support interactions and slab lengths of MoS2 increased. The slab stacks were inhibited by the strengthened strong interaction, leading to the reduction of edge/rim sites ratio that are favour for the HDS reaction. Appropriate calcination temperature (500 °C) could make the MoS2/γ‐MA‐500 possess favourable pore structure, particle dispersion, and edge/rim sites ratio, which were conducive to the mass transfer process of reactants and products, and lowered the carbon deposition rate, thus improving its catalytic activity, stability and direct hydrogenolysis desulfurization selectivity.

CoMo/Al2O3-MgO Supported Catalysts: Improvement of Hydrodesulfurization Activity and Optimization of Operational Processing

Hydrodesulfurization (HDS) plays a vital role in the production of clean fuels when more stringent environmental legislation forces the sulfur content in fuels to an ultra-low level. There are two alternative approaches for producing ultra-low sulfur diesel (ULSD) in a cost-effective way, including the activity improvement of HDS catalysts and the optimization of the operating conditions in HDS reactions. In this study, the activity improvement of HDS catalysts was first examined, and then the optimization of operational conditions was further explored to gain the ULSD in a cost-effective way. In detail, the catalysts were improved through optimizing the ratio between active metal (Mo) and promoter (Co) based on the MgO-Al2O3 as support. Precursors of the improved oxide catalysts and sulfide catalysts were characterized by various techniques, and the catalytic performances were further evaluated in the hydrodesulfurization of dibenzothiophene. Catalysts with the best catalytic performance were chosen to optimize the reaction conditions. Results show that the optimal amounts of catalysts were 4 wt.% of MoO3 and combined with 2 wt.% of CoO. Moreover, the optimal reaction conditions were reaction temperature of 240 °C, total reaction pressure of 4.0 MPa, the hydrogen-to-oil volume ratio of 300, and LHSV of 2.0 h−1. Under the optimal reaction condition, the desulfurization rate could reach to 99.8%.

Bimetallic CoMo Nanoparticles Supported over Carbon-Zeolite Composites as Dibenzothiophene Hydrodesulfurization Catalyst

Cobalt molybdenum catalysts supported on novel activated carbon-HZSM-5 composites with different mass ratios were prepared by wet-impregnation method and pre-sulfided by CS2. Characterization of these catalysts was done using X-ray powder diffraction, Fourier transform infrared spectroscopy, N2 adsorption-desorption, and scanning electron microscope analytics. Their activity for the hydrodesulfurization reaction of dibenzothiophene was investigated at atmospheric pressure in the temperature range of 250–400 °C using the fixed-bed reactor with 0.5 g of each powder and pre-sulfided with CS2. The highest conversion of dibenzothiophene at the temperature range of 300–400 °C was obtained for the CoMo/activated carbon-HZSM-5(1:1) catalyst. The best selectivity for cyclohexylbenzene, which is the dominant product according to gas chromatography results, was obtained at all temperatures using CoMo/activated carbon-HZSM-5(3:1) catalyst. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

RuS2-modified NiW/Al2O3 catalysts for refractory 4,6-dimethyl-dibenzothiophene hydrodesulfurization

Al2O3-supported noble metal (NM)-modified hydrodesulfurization (HDS) catalysts (W 15.8 wt% and Ni 3.5 wt%) were applied in refractory 4.6-dimethyl-dibenzothiophene elimination. Corresponding Ru-doped (0.5 and 0.7 wt%) materials were either dried (120 °C) or dried followed by calcining (400 °C) after NM deposition prior to activation (400 °C, 15/85H2S/H2 mixture). In solid at 0.5 wt% NM calcined after Ru deposition ruthenium was less dispersed (XRD and TPR) than over corresponding just dried one. Also, WS2 had higher dispersion (HR-TEM) on the latter. However, “NiWS” phase was enhanced (XPS) on the former material. NM-doped catalysts annealed before activation showed significantly enhanced activity (x2.4 and x1.6, solids with 0.5 and 0.7 wt% Ru, respectively) in refractory dibenzothiophene (DBT) HDS, as to that of pristine NiW/Al2O3. Enhanced hydrogenating properties of the former materials improved S elimination from sterically-hindered DBT. Conversely, Ru-doping was detrimental on NiW/alumina when non-annealed prior to activation. Unreduced Run+ and decreased pyrite-like RuS2 species (XPS) on those catalysts could be related to their strongly diminished HDS activity.

High-performance NiMoS hydrodesulfurization catalysts by one-pot hydrothermal synthesis using Ni(acac)2 for sulfur-free liquid fuels

A straightforward hydrothermal synthesis of NiMoS active phases loaded on SBA-15 was attempted. We initially prepared a catalyst by impregnating metal precursors sequentially onto SBA-15 and the subsequent hydrothermal treatment with sublimed sulfur. To obtain the one-pot catalyst, we performed the hydrothermal treatment of a mechanical mixture containing metal precursors, sublimed sulfur, and SBA-15. The catalysts were characterized by powder X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, N2 adsorption-desorption study, and high-resolution transmission emission spectroscopy. Compared to impregnation-assisted synthesis, the one-pot synthesis promoted the generation of dispersed shorter MoS2 slabs with desirable average stacking number, i.e., increased number of edge and rim sites. Therefore, the one-pot catalyst enabled the ultra-deep sulfur removal (~100%) in the dibenzothiophene hydrodesulfurization. Unlike Ni(acac)2, the utilization of Ni(NO3)2 inhibits the sulfidation of molybdenum and the dispersion of MoS2 layers, decreasing the hydrodesulfurization activity. The one-pot catalyst was able to achieve ~80% sulfur removal even after six consecutive catalytic runs under batch reactor conditions (320 °C, 6 MPa (H2), 500 ppmw S, 100 mg (mcat)) due to the persistent stability of NiMoS active phases.

Core-shell catalysts with CoMoS phase embedded in clay nanotubes for dibenzothiophene hydrodesulfurization

Nanoarchitectural strategy for design of highly active catalysts with CoMoS encased in 50-nm diameter aluminosilicate tubes (halloysite nanoclay) serving as an abundantly available natural support was proposed. This encapsulation conception implies the protection of active metal sulfides from aggregation, coking and leaching. Synthesized nanocatalytic system was investigated by TEM, XPS, N2 adsorption, hydrogen temperature programmed reduction and desorption of ammonia techniques. Using of Mo-heteropolyacid anionic precursor complex (ca. 10 wt%) possess selective loading of molybdenum oxide into 15-nm diameter inner cavity of the nanotubes (covered with positively charged alumina) by an electrostatic attraction. Subsequent sulfidation results in formation of CoMoS particulate core inside the aluminosilicate shell. These tubular nanoreactors were pelletized using alumina binder to produce a mechanically strong mesoporous catalyst efficient for hydrotreatment of diesel petroleum fraction to clean fuels.

Effect of Adding Chelating Ligands on the Catalytic Performance of Rh-Promoted MoS2 in the Hydrodesulfurization of Dibenzothiophene

Hydrodesulfurization (HDS) is a widely used process currently employed in petroleum refineries to eliminate organosulfur compounds in fuels. The current hydrotreating process struggles to remove organosulfur compounds with a steric hindrance due to the electronic nature of the current catalysts employed. In this work, the effects of adding chelating ligands such as ethylenediaminetetraacetic acid (EDTA), citric acid (CA) and acetic acid (AA) to rhodium (Rh) and active molybdenum (Mo) species for dibenzothiophene (DBT) HDS catalytic activity was evaluated. HDS activities followed the order of RhMo/ɣ-Al2O3 (88%) > RhMo-AA/ɣ-Al2O3 (73%) > RhMo-CA/ɣ-Al2O3 (72%) > RhMo-EDTA/ɣ-Al2O3 (68%). The observed trend was attributed to the different chelating ligands with varying electronic properties, thus influencing the metal–support interaction and the favorable reduction of the Mo species. RhMo/ɣ-Al2O3 offered the highest HDS activity due to its (i) lower metal–support interaction energy, as observed from the RhMo/ɣ-Al2O3 band gap of 3.779 eV and the slight shift toward the lower BE of Mo 3d, (ii) increased Mo-O-Mo species (NMo-O-Mo ~1.975) and (iii) better sulfidation of Rh and MoO in RhMo/ɣ-Al2O3 compared to the chelated catalysts. The obtained data provides that HDS catalytic activity was mainly driven by the structural nature of the RhMo-based catalyst, which influences the formation of more active sites that can enhance the HDS activity.

On the contribution of the cobalt sulfide phase to the global activity of industrial-type CoMo/Al2O3 catalysts in the HDS of DBT

To analyze if the HDS activity is the result of contributions of both CoMoS and cobalt sulfides phases, a series of CoMo/Al2O3 catalysts with increasing Co/(Co+Mo) ratios (r = 0.1, 0.2, 0.3 and 0.4) prepared by simultaneous impregnation, and composites formed with the CoMo/Al2O3 catalysts and Co/Al2O3, were tested in the hydrodesulfurization of dibenzothiophene. The catalysts were characterized by UV–Visible–NIR and infrared of adsorbed CO spectroscopies. The results showed that the amount of CoMoS adsorbing sites remains basically the same in the series of promoted catalysts, while an increase of the precursor of cobalt sulfide is observed. The activity experiments showed that the addition of Co/Al2O3 to Mo/Al2O3 or CoMo/Al2O3 catalysts promotes both the MoS2 and CoMoS phases, and that the rate constants of CoMo/Al2O3 r = 0.2 and CoMo/Al2O3 r = 0.3 can be closely reproduced with composites of CoMo/Al2O3 r = 0.1 with different amounts of Co/Al2O3, indicating that the increased activity in the series of Co-promoted catalysts is related to the presence of cobalt sulfide. It was evidenced that Co-promoted catalysts are complex systems in which several surface species contribute to the global hydrodesulfurization activity and that cobalt sulfide, far from being a spectator in HDS catalysis, has in fact a secondary but significant role in the global performance of industrial-type CoMo/Al2O3 hydrodesulfurization catalysts. All these contributions must be optimized to obtain highly active and selective hydrodesulfurization catalysts.

Modification of ZSM-5 mesoporosity and application as catalyst support in hydrodesulfurization of dibenzothiophene: Experimental and DFT studies

The hydrodesulfurization (HDS) efficiency of NiMoS supported on modified H-ZSM-5 was investigated. The support modification was achieved via desilication (DS) in 3 – 5 M NaOH solution for 0.5 – 1 h, at 65 °C. The desilication of H-ZSM-5 increased both its mesoporosity and external surface area. The catalysts acidity and active phase formation and dispersion were influenced by the desilication of the zeolite supports. The NM/B-Z1/2 catalyst shows better HDS performance with dibenzothiophene (DBT) conversion of 87% after 4 h of reaction, while the catalyst formed from pristine ZSM-5 support (NM/Z) recorded the least DBT conversion of 38%. The DFT simulation energetics revealed that the hydrodesulfurization (HDS) process proceeded via the direct desulfurization (DDS) pathway in good correlation with the experimental findings. Extensive characterization techniques were adopted to gain insight into the physico-chemical properties of the support and the catalysts. Surface area and porosity analyzer was used for textural properties information of both the support and the catalyst. The information about surface and type of acidity, the metal-support interaction, morphology, metal charge content and dispersion of active species NiMo-S was explored by FESEM, FETEM, TPD, Pyr-FTIR, FTIR, XRD and XPS

Influence of Ni on the active phase and hydrodenitrogenation and hydrodesulfurization activities of MoS2 catalysts

To obtain type II active phase with higher activity, MoS2-based catalysts were prepared by thermal decomposition of ammonium tetrathiomolybdate. The influence of Ni adding way and decomposition atmosphere on the microstructures of MoS2 slabs, chemical state of surface elements, as well as hydrodesulfurization and hydrodenitrogenation activities were investigated. Results indicated that simultaneous impregnation of Mo and Ni precursors caused in situ deposition of amorphous NiMoS4 over the support surface, which subsequently facilitated the substitution of Mo atoms by Ni atoms at MoS2 edges. Accordingly, these decorated catalysts exhibited higher dispersion of MoS2 slabs with more suitable slab length (3–5 nm) and stacking number (2–4), which attributed to larger numbers of rim and corner active sites exposed at the edges. These active sites were essential in hydrogenation and hydrogenolysis reactions. In comparison with N2 atmosphere, thermal decomposition in H2 atmosphere was more conducive to the substitution of Mo atoms by Ni atoms at MoS2 edges, which provided more active Ni-Mo-S structures for the adsorption, activation and hydrogenolysis of quinoline and dibenzothiophene molecules. The catalyst prepared by thermal decomposition of NiMoS4 in H2 atmosphere showed superior activities in the quinoline hydrodenitrogenation with 23.8% conversion and in the dibenzothiophene hydrodesulfurization with 93.3% conversion, under the conditions of 340°C, 3 MPa, a weight hourly space velocity of 23.4 h−1, H2/oil volume ratio of 600 and 0.1 g of NMS-H2 catalysts.

Conditions for increasing the hydrodesulfurization of dibenzothiophene when co-feeding naphthalene, quinoline, and indole

In this work, we report a statistically significant increase in the rates of direct C–S bond scission of dibenzothiophene when co-reactants such as naphthalene, quinoline, and indole are present during its hydrodesulfurization over a Ni–MoS2/γ-Al2O3 catalyst. The competitive adsorption of these compounds on the same active sites has usually been associated with inhibitory effects of sulfur elimination. However, we carried out statistically designed experiments at temperatures between 260 and 300 °C, concentrations of dibenzothiophene between 1.0 and 3.7 wt%, and concentrations of the co-reactants between 0.13 and 0.52 wt%, and observed that the kinetic constant of the direct desulfurization pathway can increase up to 200% when either naphthalene, indole, or quinoline is co-fed to the reaction system at 260 °C and 3.7 wt% of dibenzothiophene. Therefore, the classical paradigm that aromatics and nitrogen heterocycles always inhibit hydrodesulfurization needs reexamination.

Template-free, facile synthesis of nickel promoted multi-walled MoS2 & nano-bricks containing hierarchical MoS2 nanotubes from the bulk NiMo oxide

A low-temperature and template-free synthesis method was developed to prepare MoS2 nanotubes by sulfidation of bulk NiMo oxide. The ex-situ gas-phase low-pressure sulfidation of NiMo oxide resulted in multi-walled MoS2 nanotubes and NixSy spheres. Meanwhile, the in-situ liquid phase high-pressure sulfidation led to nanotubes formation by self-assembly of MoS2 nano-bricks vertically oriented towards the outer surface as observed by HRTEM analysis. The sulfided catalysts were evaluated for the hydrodesulfurization (HDS) of dibenzothiophene (DBT) in a batch reactor. Catalyst sulfided under ex-situ conditions exhibited good performance (76 % DBT conversion with an initial reaction rate 24 × 10−8 molDBT.(gCat.s)-1). The in-situ sulfided catalyst showed an outstanding activity (99 % DBT conversion with an initial reaction rate 105 × 10−8 molDBT.(gCat.s)-1). Which means that the in-situ sulfidation method dramatically increased the initial reaction rate by four times. A mathematical expression (RKC equation) was derived to correlate the size of the regular hexagonal MoS2 nanoparticles with its activity, for which the experimental results were validated.

Facile synthesis of few-layer MoS2 nanosheets with different morphologies supported on Al-TUD-1 for efficient hydrodesulfurization of dibenzothiophene and 4,6-dimethyldibenzothiophene

Low-cost pure aluminum-based Al-TUD-1 mesoporous materials (AT) were successfully synthesized and the corresponding NiMo/AT catalysts were modified with Citric acid (CA), which were utilized for dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) hydrodesulfurization (HDS) reactions. CA could effectively modulate the acidity and metal-support-interaction (MSI) of NiMoCA(x)/AT catalysts, which were in favor of generating more MoS2 active species with higher sulfurization degree and higher dispersion degree. The morphology of the MoS2 active phase of NiMoCA(x)/AT catalysts was changed after the addition of CA. The NiMoCA(2)/AT catalyst showed the higher B/L ratio and higher S-edge/M-edge ratio, which was conducive to the isomerization (ISO) route selectivity (81%) of 4,6-DMDBT HDS, thus resulting the improvement of HDS activity of the NiMoCA(2)/AT catalyst. The NiMoCA(2)/AT exhibited the maximal DBT and 4,6-DMDBT HDS efficiency of 99.0% and 95.5% as well as maximal kHDS and TOF values of 4,6-DMDBT HDS (13.4 × 10−4 mol⋅g−1⋅h−1, 4.7 h−1) among other series NiMoCA(x)/AT catalysts and reference commercial NiMo/Al2O3 catalyst at the Weight hour space velocity (WHSV) of 10 h−1.

Hydrodesulfurization of dibenzothiophene using novel unsupported FeMoS catalysts prepared by in-situ activation from Fe (III)-containing thiomolybdate salts

Hydrodesulfurization of dibenzothiophene using novel unsupported FeMoS catalysts prepared by in-situ activation from Fe (III)-containing thiomolybdate salts