Hydrodesulphurization Activity Research Articles

Hydrodesulfurization Catalysts from Aluminium-Containing Waste

A possibility of using aluminum hydroxide, a product of processing of the adsorbent that lost its sorption activity in purification of a polyethylene solution cyclohexane, was demonstrated in the synthesis of aluminum kaolin borate supports for hydrodesulfurization catalysis in oil refining. The influence of typical impurities V, Ti and Na in the composition of the spent adsorbent on the physicochemical and catalytic properties of supports and catalysts was determined. Alumina-kaolin-borate catalyst carriers with the Ti content of approx. 0.2% have been prepared by atomic layer deposition (ALD) of TiCl4 onto the granules. A positive effect of molecular layering with TiO2 has been revealed by temperature programmed reduction and oxidation in combination with hydrodesulphurization activity testing.Graphical

Deposition of Co onto Supported MoS2 by Water-Assisted Spreading: Increased Activity Promotion in Hydrodesulphurization of 1-Benzothiophene

Hydrodesulphurization (HDS) catalysts were newly prepared by water-assisted spreading of CoCO3.Co(OH)2 of low solubility in water onto pre-sulphided Mo species supported on several Al2O3 of surface area SBET 77-262 m2g−1, ZrO2 of SBET 108 m2g−1, and TiO2 of SBET 140 m2g−1. The spreading was followed by scanning electron microscopy (SEM-EDX). X-ray photoelectron spectroscopy (XPS) and temperature programmed reduction (H2-TPR) characterized partial re-oxidation of sulphidic Mo catalysts before Co sorption. The prepared catalysts were characterized in sulphidic form by H2-TPR. Activity of catalysts was determined in the HDS reaction of 1-benzothiophene. The spreading of Co onto sulphidic catalysts led to systematic increase of HDS activity by 16–86% in comparison to the spreading of Co onto oxide samples.

Hydrodesulfurization of Dibenzothiophene on a CoNiMo Catalyst

In order to evaluate the performance of CoNiMo/g-Al2O3, the hydrogenolysis of dibenzothiophene was carried out. The conversion of dibenzothiophene, the yields of the reaction products and the unconverted sulfur content, expressed in ppm, were determined, at different temperatures in the catalytic layer (300�C-360�C), pressures (40 bar-60 bar) and liquid hourly space velocity (1-4h-1). The hydrodesulphurization catalyst was characterized by: determining the textural characteristics (BET specific surface area, mean pore diameter and pore volume), the acidic strength distribution, morphological analysis (scanning electron microscopy - SEM) and by identification of the species (X-ray diffraction � XRD). The analysis of the textural characteristics results in an ordered mesoporous structure of the catalyst, with a specific area of 280 m2/g and a medium pore diameter of 4.42 nm. At high temperature of 360�C and pressure of 60bar, the CoNiMo/ g-Al2O3 exhibit a good activity in hydrodesulphurization, with a 100% conversion of dibenzotiophene.

Catalytic hydropyrolysis of El-Lajjun and Julia Creek shale oils using flow-through and sealed autoclaves

High-sulfur shale oils from two marine oil shales, El-Lajjun (Jordan) and Julia Creek (Australia) were subjected to hydropyrolysis using NiMo catalysts deposited on Al-SBA-15 with Si/Al ratios ranging from 10 to 75, i.e. with decreasing acidity, both in a flow-through system at 0.1 MPa H2 pressure and in sealed autoclaves at varying H2 pressure (1–6 MPa (cold, i.e., at room temperature)). For autoclave pyrolysis of El-Lajjun shale oil catalysed by NiMo-Al-SBA-15 (Si:Al = 10:1), sulfur content of oil decreased with H2 pressure, catalyst:oil ratio and temperature, pyrolysis time having little effect. Coking decreased with increasing H2 pressure, but increased with increasing temperature and catalyst:oil ratio. Time had little effect on coking. The conditions finally adopted were 400 °C, 6 MPa (cold) H2 pressure, 30 min pyrolysis time and (0.1:1.0) catalyst:oil ratio. Lower Si/Al ratios (≤50) all gave the same hydrodesulphurization (HDS) activity, but coking declined with decreasing Si/Al ratio, so that the optimum ratio was 10. The Julia Creek shale oil also showed good HDS, but was more susceptible to coking at high Si/Al ratio. The oil obtained in catalysed pyrolysis contained almost no thiophenes or benzothiophenes and had more high-boiling point material than oil from non-catalysed pyrolysis. The catalyst was successfully regenerated after use and was also effective in HDS of both raw oil shales. For the flow-through experiments, no significant hydrodesulphurization (HDS) was observed for either shale oil, but some hydrodenitrogenation (HDN) occurred for the Julia Creek shale oils.

Comparison of three-dimensional versus two-dimensional structure of mesoporous alumina as support of (Ni)MoS2 catalysts for HDS

Ordered mesoporous alumina (OMA), and commercial non ordered mesoporous alumina (CMA) were used as support to synthesize NiMo catalysts with a metal loading of 16%Wt. OMA synthesis was made using Pluronic (P123) as structure directing agent, and ethanol as a solvent. The physical and chemical properties of the supports and catalysts were characterized by XRD, nitrogen physisorption, X-ray photoelectron spectroscopy (XPS), Transmission electron microscopy (TEM), acidity of support was studied by n-butylamine adsorption followed by FTIR and catalytic performance was evaluated by hydrodesulphurization of dibenzothiophene (DBT) reaction. Main difference of supports is a two-dimensional arrangement of pores on OMA support and a three-dimensional arrangement for CMA. OMA support has more surface area available to disperse Mo and Ni species than the CMA material, besides OMA present slight acidity on its surface, and these characteristics of support leaded to obtain a NiMoS2 active phase better structured to present higher activity for DBT hydrodesulphurization and higher selectivity for direct desulfurization than the obtained for CMA supported catalyst, despite CMA presented interconnected pores and higher pore diameter.

Hydrotreating of gasoline and diesel oil fractions over modified alumina/zeolite catalysts

This paper deals with hydrotreating of straight-run gasoline (SRG) and diesel oil fractions (DOF) over new Ni (Co) containing alumina/zeolite catalysts, modified by transition metals (W and Mo) with the addition of P and Ce elements. In hydrotreating of the DOF, the CoO-WO3-CAR catalyst has the highest hydrodesulphurization activity that reaches 97.2% at 400 °C, P = 4MPa and V = 2h−1. Moreover, increasing of pressure until 5 MPa leads to reducing of the sulfur content up to 0.0007%. The greatest decrease in the pour (−58.9 °C) and the cloud (−56.7 °C) points during the hydrotreating of the DOF is observed using the NiO-MoO3-CAR catalyst. The octane number of SRG after hydrotreating over the NiO-MoO3-CAR catalyst rises up to 88.6. Obtained results clearly show that using synthesized catalysts, motor fuel with Euro-5 standard could be obtained.

Hydrodesulphurization of dibenzothiophene on NiMoS catalysts: Impact of the carbon support on the reaction kinetics

The hydrodesulphurization (HDS) activity of nickel molybdenum sulphided catalysts supported on activated carbon (NiMoS/AC), activated petroleum coke (NiMoS/APC), and conventional alumina (NiMo/γ‐Al2O3) have been compared using dibenzothiophene (DBT) as a model reactant. The reactions were carried out in a slurry‐phase batch microreactor at different reaction times (30–120 min) and temperatures (588–638 K) and a fixed H2 pressure (4.8 MPa). The NiMoS/APC catalyst had higher dispersion than the NiMoS/AC catalyst, resulting in a higher DBT conversion activity per gram of catalyst on the NiMoS/APC catalyst. However, similar activities were obtained on both catalysts when accounting for the NiMoS dispersion. The NiMoS/APC activity was marginally lower than the NiMoS/γ‐Al2O3 commercial catalyst, suggesting that activated petcoke is a promising support for NiMoS catalysts. The pseudo 1st order rate constants for both the direct desulphurization (DDS) and hydrogenation (HYD) reaction pathways were of similar magnitude on the NiMoS/APC catalyst, as were the apparent activation energies. Hence the selectivities for HYD versus DDS were favoured equally on the NiMoS/APC, unlike on NiMoS/Al2O3 where the DDS of DBT is favoured, or the NiMoS/AC where the DDS of DBT is favoured at higher temperatures (> 603 K). The results of this study demonstrate that raw petcoke derived from Canadian oilsands can be converted to a useful catalyst support for hydrotreating catalysts that have high NiMoS dispersion and HDS activity, comparable to that of a commercial NiMoS/Al2O3 catalyst.

Effect of boron on the efficiency of MoCo catalysts supported on alumina for the hydrodesulfurization of liquid fuels

Abstract The effect of boron content on hydrodesulphurization (HDS) activity was investigated under different optimized conditions. γ-Al2O3 was loaded with MoCo and then doped with boron. The obtained materials, i.e. AlMoCoB0%, AlMoCoB2%, and AlMoCoB5% were characterized by N2-physisorption, X-ray diffraction, temperature programmed analysis by reduction and desorption, Fourier-transform infrared spectroscopy, a scanning electron microscopy, transmission electron microscopy, and thermogravimetric analysis. The catalytic activity of the prepared catalysts was evaluated for the HDS of dibenzothiophene (DBT) using a Parr batch reactor at T = 300 °C and under 50 bar hydrogen partial pressure. The textural properties of the prepared catalysts were enhanced by introducing the boron. For example, the BET surface area of AlMoCoB5% was 206 m2/g which is higher than that of both AlMoCoB0% and AlMoCoB2%. The acidity and dispersion AlMoCoB5% were 0.77 and 2.46 (mmol/g), respectively, which increase its HDS activity. The boron enhanced the particle dispersion, leading to an improvement in the catalytic activity of the MoCo catalysts in the elimination of sulfur content. Experimental factors (such as temperature, pressure, the dosage of the catalysts and contact time) were investigated and optimized using a central composite design. The results revealed that the HDS was improved by increasing the temperature, pressure, and catalyst dosage. The optimum contact time was found to be 6 h with a dosage of 0.6 g. The experimental results indicated that AlMoCoB5% has the highest HDS activity, achieving more than 98% of sulfur removal, which is below the allowed sulfur level. The excellent catalytic activity of the AlMoCoB5% catalyst in the HDS of DBT is particularly useful for the ultradeep HDS of fuels.

A theoretical study on reaction mechanisms and kinetics of thiophene hydrodesulfurization over MoS2 catalysts

In the present work, thiophene hydrodesulphurization (HDS) over the Mo-edge, the S-edge, and the Mo-S connection edge of MoS2 catalyst with 50% sulfur coverage was studied using first-principles based microkinetic modeling. Two parallel HDS routes, i.e., direct desulfurization (DDS) and hydrogenation (HYD) were taken into account. It has been found that the major reaction route of thiophene HDS on the Mo- and the Mo-S edges is temperature dependent. In the low temperature range of 500–600 K, the HYD route is dominant, leading to the C4H8 formation. As the temperature increases, the DDS route becomes competitive with the HYD route. At the temperature above 650 K, the DDS route will be the dominant HDS reaction route on the Mo- and the Mo-S edges. The DDS route leading to the formation of C4H6 is the major thiophene HDS reaction route on the S-edge in the entire temperature range of 500–750 K. The microkinetic modeling results show the overall HDS activity on the S-edge is lower than it on the Mo- and the Mo-S edges. The Mo-S edge also provides a preferential reaction pathway, which facilitates 2-hydrothiophene migration from the Mo-edge to the S-edge, followed by remaining elementary steps with lower activation barriers in the DDS route.

Relative activity of Niobia-supported CoMo hydrodesulphurization catalyst prepared with NTA: A kinetic approach

A sulphide CoMo/Nb2O5 HDS catalyst was prepared for the first time using nitrilotriacetic acid (NTA) as complexing agent, where the impregnation solution consisted of NTA, cobalt carbonate and ammonium heptamolybdate. It contained neither NH4OH nor NO3− ions. The hydrodesulphurization activity of the catalyst was tested using as model sulphur compound that of thiophene at 1.0MPa and 400°C. The ratio of activities (based on pseudo-first order kinetics) expressed in terms of the rate constant k, where the latter was estimated from specific reaction rate data per mass of catalyst, for the NTA-CoMo/Nb2O5 and CoMo/Nb2O5 catalysts was found to be 6.6. Thus, using NTA shifted CoMo/Nb2O5 system from a low activity catalyst (as observed in the literature) to a high activity catalyst worthwhile for further investigations (present results). The NTA-CoMo/Nb2O5 (SBET=40m2g−1) was more active than commercial CoMo/Al2O3 (SBET=194m2g−1) not only in terms of specific activity normalized per total surface area (mols m−2s−1, 5.7 times larger) but also in terms of specific activity normalized per mass of catalyst sample (mols g−1s−1, 1.2 times larger).

Characterization and HDS activity of sulfided Co[sbnd]Mo[sbnd]W/SBA-16 catalysts: Effects of P addition and Mo/(Mo + W) ratio

Two series of SBA-16-supported CoMoW ternary sulfide catalysts with atomic ratio r=Mo/(Mo+W) ranging from 0.3 to 0.7 were prepared by the simultaneous impregnation of SBA-16andphosphated-SBA-16 substrates with metal precursors. The samples were characterized by a variety of techniques (chemical analysis, N2 physisorption, SEM, XRD, DRS UV–vis, TPR, TPD-NH3, Raman spectroscopy, HRTEM, XPS and coke burning). The catalytic performance was evaluated in the hydrodesulphurization (HDS) of dibenzothiophene (DBT), carried out in a batch reactor at 350°Cand3.1 MPaof total H2 pressure. The maximum activity at the same atomic ratio r=0.4 was observed for the catalysts supported on SBA-16 modified with phosphorous (r=0.4(P)). HRTEM evidenced that this was because different MoS2 crystalline structures were formed: the P-free sample prepared with Mo/(Mo+W) atomic ratio of 0.6 (r=0.6) exhibited the MoS2-2Hcrystalline structure whereas the P-containing samples prepared with Mo/(Mo+W) atomic ratio of 0.4 (r=0.4(P)) exhibited the interplanar distance corresponding to (003) planes of MoS2-3R crystalline structure. Additionally, the best activity of the r=0.4(P) sulfide catalyst was linked with the enhancement of the WS2 species surface exposure accompanied with a larger sulfidation degree of W species (from XPS).

NiMo/alumina hydrodesulphurization catalyst modified by saccharose: Effect of addition stage of organic modifier

NiMo/Al2O3 catalysts, obtained by one‐pot simultaneous impregnation, were modified by saccharose (SA, at Ni/SA = 1 mol ratio) addition. To address the influence of stage of saccharide impregnation on the hydrodesulphurization activity of sulphided catalysts, three different preparation methodologies were followed: (a) modification of already calcined (400 °C) NiMo/Al2O3 by SA impregnation; (b) SA deposition directly onto the alumina support, prior to Ni + Mo impregnation; (c) simultaneous Ni + Mo + SA deposition. Materials were characterized by N2 physisorption, X‐ray diffraction, infrared (IR) spectroscopy, UV‐vis spectroscopy, and temperature‐programmed reduction (TPR), and tested on liquid‐phase dibenzothiophene (DBT) conversion (batch reactor, T = 320 °C, P = 7.2 MPa, n‐hexadecane as solvent). The last methodology resulted in the catalyst with the highest DBT hydrodesulphurization (HDS) activity, on a pseudo‐first order kinetic constant basis. A decreased proportion of tetrahedral Mo6+ species due to diminished interaction with the carrier, increased reducibility of octahedral Mo6+, and Ni complexation as well seemed to play determining roles in the trends of the activity observed. Simultaneous saccharose addition during NiMo phase impregnation required no additional preparation steps to efficiently integrate the organic modifier.

HDS of dibenzothiophenes and hydrogenation of tetralin over a SiO2 supported Ni-Mo-S catalyst

A one-step synthesized Ni-Mo-S catalyst supported on SiO2 was prepared and used for hydrodesulphurization (HDS) of dibenzothiophene (DBT), and 4,6-dimethyl-dibenzothiophene (4,6-DMDBT), and for hydrogenation of tetralin. The catalyst showed relatively high HDS activity with complete conversion of DBT and 4,6-DMDBT at temperature of 280 °C and a constant pressure of 435 psi. The HDS conversions of DBTand 4,6-DMDBT increased with increasing temperature and pressure, and decreasing liquid hourly space velocity (LHSV). The HDS of DBT proceeded mostly through the direct desulphurization (DDS) pathway whereas that of 4,6-DMDBT occurred mainly through the hydrogenationdesulphurization (HYD) pathway. Although the catalyst showed up to 24% hydrogenation/dehydrogenation conversion of tetralin, it had low conversion and selectivity for ring opening and contraction due to the competitive adsorption of DBTand 4,6-DMDBT and insufficient acidic sites on the catalyst surface. Open image in new window

REACTIVITY AND MORPHOLOGY OFNi,Mo, ANDNi–MoOXIDE CLUSTERS SUPPORTED ON MCM-48 TOWARD THIOPHENE HYDRODESULPHURIZATION

In this paper, the morphology, chemical composition and reactivity of MCM-48 powders impregnated with Ni , Mo or both toward hydrodesulphurization (HDS) of thiophene were characterized. The reactivity of the catalyst was quantitatively compared with a standard industrial catalyst (from HaldorTopsoe, Denmark) and a novel WS2nanotube-based catalysts (from R. Tenne, Israel). Morphology and chemical composition were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), and EDX elemental maps. Reactivity was determined in a gas-chromatograph based mini flow reactor using thiophene as a probe molecule. The sulfided MCM-48 supported Mo catalyst showed the largest HDS activity with turnover frequencies (TOF) about half as large as for the commercial system under the test conditions used here. Presulfiding did increase activity of all MCM-48 catalysts.

Crystallographic studies through HRTEM and XRD of MoS2nanostructures

Mesoporous and silica-based SBA-15 and SBA-16 materials were used as supports of novel nanostructured ternary Co(Ni)-Mo-W hydrodesulphurization (HDS) catalysts. These materials have shown a high catalytic activity in HDS of dibenzothiophene (DBT) reactions, even much higher compared with commercial catalysts. An exploration was made on the structure of both the supports as well as on tri-metallic sulfide HDS catalysts. The sulfided catalysts were tested in the HDS of DBT performed in a batch reactor at 623 K and total pressure of 3.1 MPa. The calcined and fresh sulfide catalysts were characterized by a variety of techniques, such as N2 adsorption-desorption isotherms, Temperature-Programmed Desorption (TPD) of NH3, X-ray Diffraction (XRD) and High Resolution Transmission Electron Microscopy (HRTEM). It has been found that both the morphology of the supports as its modification with varying amounts of phosphorus affect the catalytic activity of these nanostructured materials in HDS of DBT reactions. Furthermore, the nanostructures which correspond to the tri-metallic sulfided catalysts exhibit a typical morphology of MoS2 – 2H structure. The present work shows the microstructural study of these nanostructured materials, carried out from HRTEM images and XRD analysis. Both techniques, X–ray Diffractometry and High Resolution Transmission Electron Microscopy, play a fundamental role in the characterization of the microstructure of HDS catalytic nanomaterials, as well as in understanding the various phenomena involved, starting from the synthesis process unto the final performance of those materials.

Hydrotreating of waste lube oil by rejuvenated spent hydrotreating catalyst

Large quantities of catalysts are used in the Egyptian refining industry for the purification and upgrading of various petroleum streams. These catalysts gradually lose activity through deactivation with time and the spent catalysts were usually discarded as solid waste. On the other hand, waste lube oil contains heavy metals coming from undergirded base oil and additives, these metals have carcinogenic effect and cause serious environmental problems. Studies are conducted on the reclamation of metals, rejuvenation and reuse of the spent hydrotreating catalyst (Mo–Ni/Al) which have been used in re-refining of waste lube oil at Alexandria Petroleum Company. Three leaching solvents were used: oxidized oxalic acid, benzoic acid and boric acid at different concentrations (4%, 8% and 16%), different oxidizing agents (H2O2 and Fe(NO3)3) and different modes of addition of oxidizing agents (batch and continuous). The results indicated that 4% oxalic acid+5% Fe(NO3)3 at continuous addition of oxidizing agents was the most efficient leaching solvent to facilitate metal removal and rejuvenate catalyst. The fresh catalyst was applied for re-refining of waste lube oil under different reaction temperatures (320–410)°C in order to compare the hydrodesulphurization (HDS) activity with both the fresh, treated and spent catalysts. The results indicated that the rejuvenation techniques introduce a catalyst have HDS activity nearly approach to that the fresh of the same type.

Effect of method of preparation on hydrodesulphurization activity of Co- or Ni-promoted MoS2/SBA-15 catalysts

Ordered mesoporous material SBA-15 was synthesized and used as a support for the preparation of molybdenum sulphide catalysts through precipitation from homogeneous solution (PFHS) technique with the Mo content varying from 2–12 wt%. The prepared catalysts were evaluated for thiophene hydrodesulphurization catalytic activities at 400°C. Catalysts prepared through PFHS method resulted in highly dispersed MoS2 catalysts, which were inferred from powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), low temperature oxygen chemisorptions (LTOC) and BET surface area analysis. The relationship between XPS intensity ratio, oxygen chemisorption and catalytic activities is discussed in terms of highly dispersed nano particles of MoS2 and its consequence in accommodating more promoted atoms at the edge sites.

Effect of Annealing Temperature on Co–MoS2 Nanosheets for Hydrodesulfurization of Dibenzothiophene

The effect of annealing temperature on the structure of unsupported Co-promoted MoS2 nanosheets, prepared by mechanical activation of MoO3, S and Co(NO3)2·6H2O followed by annealing in an Ar atmosphere, is reported. An increase in annealing temperature reduced the catalyst surface area but increased the MoS2 stack height. Annealing temperatures above 600 °C also produced segregated CoxSy phases. The dibenzothiophene hydrodesulphurization activity and the direct desulfurization (DDS) to hydrogenation product ratio of the Co–MoS2 catalysts was significantly higher than for MoS2. Moreover, the DDS product selectivity of the Co–MoS2 catalysts was enhanced with increased annealing temperature up to 600 °C. Above 600 °C, the loss in activity and selectivity was due to segregation of CoxSy species and significant sintering of the MoS2 crystallites. Similar effects of high temperature sintering on the activity of MoS2 were also observed.

Novel MoO2/carbon hierarchical nano/microcomposites: synthesis, characterization, solid state transformations and thiophene HDS activity

Novel MoO(2)/C nano/microcomposites were prepared via a bottom-up approach by hydrothermal carbonization of a solution of glucose as a carbon precursor in the presence of polyoxometalates (POMs: phosphomolybdic acid [H(3)PMo(12)O(40)] and ammonium heptamolybdate tetrahydrate [(NH(4))(6)Mo(7)O(24)]·4H(2)O). The structural characterization by FT-IR, XRPD, SEM and TEM analyses revealed the controlled formation of hierarchical MoO(2)/C composites with different morphologies: strawberry-like, based on carbon microspheres decorated with MoO(2) nanoparticles; MoO(2)/C core-shell composites; and irregular aggregates in combination with ring-like microstructures bearing amorphous Mo species. These composites can be fine-tuned by varying reaction time, glucose/POM ratio and type of POM precursor. Subsequent transformations in the solid state through calcinations of MoO(2)/C core-shell composites in air lead to hollow nanostructured molybdenum trioxide microspheres together with nanorods and plate microcrystals or cauliflower-like composites (MoO(2)/C). In addition, the MoO(2)/C composite undergoes a morphology evolution to urchin-like composites when it is calcined under nitrogen atmosphere (MoO(2)/C-N(2)). The MoO(2)/C strawberry-like and MoO(2)/C-N(2) composites were transformed into Mo carbide and nitride supported on carbon microspheres (Mo(2)C/C, MoN/C, and MoN/C-N(2)). These phases were tested as precursors in thiophene hydrodesulphurization (HDS) at 400 °C, observing the following trend in relation to the thiophene steady-state conversion: MoN/C-N(2) > MoN/C > Mo(2)C/C > MoO(2)/C-N(2) > MoO(2)/C. According to these conversion values, a direct correlation was observed between higher HDS activity and decreasing crystal size as estimated from the Scherrer equation. These results suggest that such composites represent interesting and promising precursors for HDS catalysts, where the activity and stability can be modified either by chemical or structural changes of the composites under different conditions.

Comparison of the morphology and HDS activity of ternary Ni(Co)-Mo-W catalysts supported on Al-HMS and Al-SBA-16 substrates

This research compares the hydrodesulphurization (HDS) activity of supported Co(Ni)-Mo-W ternary catalysts with respect to the nature of the support (hexagonal mesoporous silica (HMS) versus SBA-16 material having cage-like mesoporous structure), the type of promoter (Co vs. Ni) and the nature of Al species formed after support modification with Al. Both Al-HMS and Al-SBA-16 mesoporous silica substrates were prepared by the one-pot sol–gel synthesis method via the neutral templating pathway using dodecylamine and Pluronic F127 as surfactants, respectively. The oxide precursors were characterized by a variety of techniques (N2 adsorption–desorption isotherms, XRD, DRS UV–vis spectroscopy and 27Al NMR), whereas sulphided catalysts were characterized by XPS and HRTEM, and tested in the HDS of DBT conducted in a high-pressure batch reactor at T=350°C and P=3.1MPa. The activity results revealed that NiMoW/Al-HMS catalyst was more active than all Co-promoted catalysts (including a commercial CoMo/Al2O3 catalyst). The HDS activity was found to be markedly influenced by the textural properties of support and the dispersion of the active phases on the catalyst surface. It has been hypothesised that the presence of extraframework AlNO3 phases on the surface of CoMoW/Al-SBA16 compromises its HDS activity because of the formation of a less active “onion-type” Mo(W)S2 structure.