Hydrodesulphurization Of Dibenzothiophene Research Articles

Influence of titanium oxide on the performance of molybdenum catalysts loaded on zeolite toward hydrodesulfurization reactions

In this work, molybdenum, cobalt, and vanadium (MCV) based catalysts were loaded on zeolite Y (Z) and modified with different ratios of titanium oxide (0, 5 and 10%) as co-support (ZT). The catalysts were characterized using a scanning electron microscope (SEM), x-ray photoelectron spectroscopy (XPS), electron dispersive x-ray spectroscopy (EDX), powder x-ray diffraction (XRD), N 2 adsorption-desorption isotherm, Fourier-transform infrared spectroscopy (FTIR), and temperature-programmed desorption (TPD). The prepared catalysts were evaluated for the hydrodesulfurization (HDS) reactions of dibenzothiophene (DBT). The incorporation of titania within the Z support was used to enhance the interaction between the active phases and the support surface through better distribution of the catalyst nanoparticles on the composite support. From the BET measurements, all of the catalysts exhibited the type IV isotherm with micro/mesoporous contributions. TPD was applied to illustrate the calcined catalyst acidity, which confirmed the positive role of titania in increasing the acidic strength of the catalyst. The XRD demonstrated the introduction of titania to the support which is clear from the characteristic peaks of titania. The elemental compositions of the catalyst and dispersion on the support surface were confirmed by EDX and x-ray mapping. The catalytic performance of 5% and 10% titania (ZT5-MCV and ZT5-MCV) showed higher activity compared to the control catalyst without titania (Z-MCV). A comparison of this catalyst with those reported in the literature points out that it is a promising candidate for fuel HDS. • MoCo-Zeolite/titania showed excellent hydrodesulphurization of dibenzothiophene. • Direct desulfurization mechanism was dominant based on characterization results and GC-SM. • The work is offering a convenient approach to prepare an effective HDS catalyst.

Synthesis of Co2Si@C and Its Catalytic Performance in the Hydrodesulphurization of Dibenzothiophene

Co2Si@C catalyst has been rapidly synthesized via a microwave-assisted pyrolysis route and applied for the hydrodesulphurization of dibenzothiophene.The synthesized Co2Si@C catalyst was analyzed and characterized by X-ray diffraction,X-ray photoelectron spectroscopy,transmission electron microscopy-energy and nitrogen adsorption-desorption.Co2Si@C catalyst possesses an ordered and uniform mesoporous structure,high cobalt content(21%),high specific surface area(117 m^2·g^-1)and small nanoparticles(8~12 nm).Owing to the strong modification of structure and properties by silicon,the nanoparticle size effect,and high cobalt content,the Co2Si@C catalyst exhibited good activity and high selectivity to DDS under mild reaction conditions(340℃and 3.0 MPa),in which the selectivity to diphenyl(BP)is more than 60%.

Activity Evaluation of CoMo Nanoparticles Supported on Meso-microporous Composites in Dibenzothiophene Hydrodesulphurization

CoMo-supported mesoporous catalysts were synthesized by 50 wt% of HZSM-5 and 50 wt% of FSM-16, KIT-6, and MCM-48. These catalysts were prepared by the wet-impregnation method and pre-sulfided with CS2. The catalytic performance was evaluated for HDS reaction of dibenzothiophene over a temperature range of 250-400 °C in a micro fixed-bed reactor under atmospheric pressure. The supported CoMo bimetallic catalysts were characterized by XRD, XRF, FT-IR, N2 adsorption-desorption, and SEM. The CoMo/KIT-6/HZSM-5 indicate higher activity than other catalysts at 400 °C for dibenzothiophene hydrodesulphurization. Also, the best selectivity to cyclohexylbenzene (CHB) is related to CoMo/FSM-16/HZSM-5. The activation energy was also calculated for all prepared catalysts for the conversions of less than 10%; according to which, the activation energy for CoMo/KIT-6/HZSM-5 is less than other catalysts (~21 kJ/mol) which can be related to the appropriate pore size and high surface area of the support. Copyright © 2020 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).

Effect of ultrasonication and chelating agents on the dispersion of NiMo catalysts on carbon for Hydrodesulphurization

The effectiveness of the ultrasonication (US) and chelating agents in the dispersion of NiMo supported on activated carbon were examined. Accordingly, NiMo catalysts supported on carbon were prepared through co-impregnation of the support using US or the addition of chelating agents namely citric acid (CA) or ethylenediaminetetraacetic acid (EDTA) to facilitate the dispersion of the metals on the support. A surface area analyzer was used to provide the BET surface area measurements. Fourier-transform infrared spectroscopy (FTIR) and a powder X-ray diffractometer were used for the characterization of the structure of the prepared materials. Scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX) analysis of the morphology and surfaces of the mapping of the prepared material was obtained to get insight into the metal dispersion on the support. Results revealed a uniform dispersion of the nickel and molybdenum particles on carbon, especially in the case of using EDTA as a dispersion agent. Hydrodesulphurization of dibenzothiophene on the prepared catalysts was tested in a high-pressure batch reactor 1000 ppm dibenzothiophene in decalin as a model fuel. The results indicated that the chelating agents have a positive impact on hydrodesulphurization (HDS) efficacy and the EDTA has more effect than others. 97 % HDS was achieved using NiMo/AC(EDTA) while 94 % and 92 % were obtained using NiMo/AC(CA) and NiMo/AC(US), compared to 89 % without the use of US and chelating agents.

Reactor de plasma de lecho fluidizado giratorio para la preparación de nanopartículas soportadas

A swirling fluidized bed reactor design for the preparation of supported nanoparticles is reported. It uses a DC plasma torch that decomposes and vaporizes salt precursors; the cationic part condenses as metal nanoparticles on a powder support. Any fluidizable granular material can be used as support, as long as it withstands the temperatures of the plasma torch. The torch is located at the center of the reactor axis and the powder is fluidized using a cyclonic action (swirl) to minimize the space where the grains could come into direct contact with the plasma zone. The reactor was tested for silver nanoparticles (AgNPs) supported on silica-alumina, using silver nitrate as precursor. The results show large grains decorated with nano-sized metal particles. Depending on the load of silver nitrate, the size of the nanoparticles can range from 3 to 50 nm, as measured using transmission electron microscopy. They are in a non-oxidized state, as revealed with x-ray photoelectron spectroscopy. The AgNPs/SiO2–Al2O3 composite was tested as a catalyst in the hydrodesulphurization of dibenzothiophene. This method can be scaled up to produce large quantities of supported metallic particles. Its inherent simplicity, high processing speed and the low operating cost are its main advantages.

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.

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 Mg as Impurity on the Structure of Mesoporous γ-Al203: Efficiency as Catalytic Support in HDS of DBT

Abstract This work shows the study of two alumina materials synthesized from aluminum sulfate with different purity by hydrolysis-precipitation route. The main difference between the aluminum salt precursors was the lower cost of one of them which was due to the higher percentage of magnesium species as impurity. Both materials showed different mesoporous structure nano-fibrillar. The physic-chemical properties of these materials were studied by several characterization techniques as XRD, XRF, BET, 27Al MAS NMR, Pyridine adsorption FT-IR, FE-SEM/EDX, TEM and XPS. Furthermore, these materials were used as supports in the formulations of NiMo-based catalysts which were obtained by impregnation by the incipient wetness method of Ni and Mo salts in 3.3 and 15 wt. % respectively. The two NiMo/γ-Al2O3 sulfide catalysts were evaluated as catalysts in the reaction of hydrodesulphurization (HDS) of dibenzothiophene (DBT), using a high-pressure batch reactor at 350 °C and 3.1 MPa and time reaction of 5 h−1. The NiMo/γ-Al2O3 catalyst prepared by aluminum sulfate of low purity and lower cost exhibited the highest HDS efficiencies, 95 %, respectively, which were mainly ascribed to the presence of Mg (0.9 wt. %) as impurity.

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.

Enhancement of dibenzothiophene hydrodesulphurization via hydrogenation route on NiMoW catalyst supported on HMS modified with Ti

This study shows that ternary Ni-Mo-W sulfide catalysts supported on hexagonal mesoporous silica modified with Ti (HMS-Ti) showed a high enhancement of dibenzothiophene (DBT) transformation via hydrogenation route with respect to their Ti-free counterpart. The reaction of hydrodesulphurization (HDS) of DBT was carried out at in a batch reactor at 320°C and 5.5MPa of total H2 pressure. The catalysts were characterized by a variety of techniques (chemical analysis, N2 adsorption-desorption isotherms, low- and wide-angles XRD, TPR, TPD-NH3, DRS UV–vis, TPO/TG and HRTEM). At reaction time of 5h, all synthetized catalysts exhibited higher DBT conversion (84–100%) than both commercial NiMo/γ-Al2O3 and NiW/γ-Al2O3 catalysts (59 and 69%, respectively). For all catalysts, the DBT transformation occurs via direct desulfurization (DDS) and hydrogenation (HYD) pathways. The DDS was the main reaction route for Ti-free sample whereas for both Ti-containing samples the DBT transformation occurs mainly via HYD reaction route. At a reaction time of 5h, the best catalyst (NiMoW/HMS-Ti1) exhibited 100% of DBT conversions and the highest yield of hydrogenation route products. From the activity results, it is concluded that only the structure of Ti species is relevant for the catalyst activity, but not the amount of Ti incorporated in the HMS framework. The superior activity of sulfide NiMoW/HMS-Ti1 is linked with the best properties of its oxide precursor: a lowest band energy gap and a large amount of Mo(W)6+ ions having octahedral coordination. After sulfidation, the best catalyst exhibited the “onion-type” Mo(W)S2 structures which offer the best conditions for the formation of “bright rim” Mo edge sites, which are known to be active sites for DBT transformation via HYD reaction route.

Kinetics of simultaneous HDS of DBT and 4‐MDBT/4,6‐DMDBT over CoMoP/γ‐Al2O3catalysts

AbstractA series of CoMo/γ‐Al2O3 catalysts were prepared with an addition of 0.0, 0.5, 1.0, or 1.5 % phosphorus pentaoxide to investigate the influence of phosphorus addition on the simultaneous hydrodesulphurization (HDS) of refractory sulphur compounds. Two sets of HDS experiments were carried out using sulphur bearing model compounds: (i) DBT (dibenzothiophene) with 4‐MDBT (4‐methyl dibenzothiophene) and (ii) DBT (dibenzothiophene) with 4,6‐DMDBT (4,6‐dimethyl dibenzothiophene). The Langmuir‐Hinshelwood mechanism based kinetics model was developed from the experimental conversion and product distribution data for simultaneous HDS of the two sulphur compounds via direct desulphurization (DDS) and hydrogenation (HYD) routes. The kinetic model fits the experimental data quite adequately for all the species. The HDS rate for DBT was found to be approximately 2 and 7 times higher than that estimated for 4‐MDBT and 4,6‐DMDBT, respectively. Enhancement of HDS rate by P addition was observed up to 0.01 g/g (1.0 wt%) P2O5 while a higher amount of P is not advantageous. A marginal preference towards HYD pathway was observed for the HDS of 4,6‐DMDBT while the DDS route was predominant during the HDS of DBT and 4‐MDBT.The trends in values of the rate constants estimated by the Langmuir‐Hinshelwood kinetic model compared well with pseudo‐first rate constants.

Influence of HZSM-5 content on behavior of CoMo/HZSM5-HMS composite catalysts in hydrodesulphurization of dibenzothiophene

CoMo-supported micro/mesoporous catalysts (CoMo/HZSM5(x)-HMS) were synthesized by varying the weight percent of zeolite (10, 20, 30 and 40 wt%). Catalytic functionalities were investigated for hydrodesulphurization reaction of dibenzothiophene over a wide temperature range of 250–400 °C. Characterization methods as XRD, XRF, FT-IR, UV–Vis DRS, NH3-TPD, H2-chemisorption, nitrogen adsorption–desorption and TGA confirmed the obtained results from these catalysts. A significant enhancement of the catalytic activity was observed for the catalysts supported on CoMo/HZSM5(20)-HMS at T = 350 °C (>97%).

Unsupported trimetallic Ni(Co)-Mo-W sulphide catalysts prepared from mixed oxides: Characterisation and catalytic tests for simultaneous tetralin HDA and dibenzothiophene HDS reactions

Unsupported A-Mo-W (A=Ni or Co) sulphide catalysts were obtained from mixed oxides containing different W:Mo ratios. An in situ liquid-phase sulphidation of the mixed oxides in a batch reactor was followed by catalytic tests in a liquid-phase reaction (at 613K and 70bar), using a mixture of dibenzotiophene (DBT) and tetralin (THN) as the feed. After the catalytic tests, the bulk sulphide catalysts were characterised by nitrogen physical adsorption, XANES/EXAFS, SEM and HR-(S)TEM. The HR-TEM images showed randomly oriented, stacked-layer particles typical of Mo (W) sulphides and an elemental HR-STEM mapping evidenced Mo/W homogeneous distribution in the trimetallic sulphides. The EXAFS results for the trimetallic catalysts are consistent with the presence of nickel or cobalt sulphide domains, and Mo1-xWxS2 solid solutions. The intralayer Mo:W solid solutions were confirmed to be thermodynamically stable with respect to phase separation by DFT calculations, which were also used to aid in the interpretation of the EXAFS results. The effect of the W:Mo ratio on the catalytic properties of the Ni- and Co-containing series was found to be different. For the Ni series, increasing the W content caused an activity increase in THN hydrodearomatization (HDA) relative to DBT hydrodesulphurization (HDS), while it had little influence on the relative contribution of the direct desulphurisation (DDS) route with respect to the previous hydrogenation (HYD) route for DBT HDS. In contrast, for the Co series, the activities and selectivities were essentially insensitive to the W content. Both the Ni and Co series of unsupported sulphides were more selective for the HYD route in DBT HDS than a supported NiMo/Al2O3 catalyst.

Interaction between Ni promoter and Al2O3 support and its effect on the performance of NiMo/γ-Al2O3 catalyst in hydrodesulphurization

A series of NiMo/γ-Al2O3 catalysts with different NiO loadings were prepared and characterized by XRD, BET, 27Al-MAS NMR, Py-IR and HRTEM. The activity of these NiMo/γ-Al2O3 catalysts in the hydrodesulphurization (HDS) of dibenzothiophene (DBT) was evaluated in a high pressure micro reactor; the interaction between Ni promoter and γ-Al2O3 support as well as its effect on the nanostructure of active MoS2 phase and HDS performance was then investigated. The results indicate that Ni promoter prefers to interact with the tetra-coordinated unsaturated aluminum sites on the support surface. With the increase of NiO loading, the average number of stacking layers for the MoS2 clusters in the sulfided NiMo/γ-Al2O3 catalysts is increased at the expense of the average length. As the slim MoS2 clusters are more active for the HDS of DBT, the addition of Ni promoter is then effective to enhance the catalytic activity of NiMo/γ-Al2O3 in HDS, but may lead to a slight decrease in the hydrogenation selectivity.

Optimization of MgO/Al2O3 ratio for the maximization of active site densities in the Ni2P/MgAlO catalysts for the hydrotreating reactions

The Ni2P/MgAlO catalysts with different MgO/Al2O3 ratios were prepared by the phosphidation of corresponding Ni/MgAlO catalysts with triphenylphosphine in liquid phase. It was found that the MgO/Al2O3 ratio affected the Ni2P/MgAlO catalysts significantly. The Ni2P/MgAlO catalyst with the MgO/Al2O3 ratio of 3 (w/w) exhibited the highly dispersed Ni2P particles (∼9nm) with the highest CO uptake (344µmol/g) and thus the highest activities for the hydrotreating reactions. However, based on the CO uptakes on the used catalysts, the TOF values for the hydrodesulphurization of dibenzothiophene as well as those for the hydrogenation of tetralin on all the Ni2P/MgAlO catalysts were respectively similar, indicating that the MgO/Al2O3 ratio did not affect the intrinsic activities of Ni2P supported on the MgAlO support for the hydrotreating reactions.

Synthesis and characterization of mechanically activated bulky molybdenum sulphide catalysts

Bulky catalysts on the basis of MoS 2 nano-crystallites have been obtained for the first time from commercial molybdenite in one-step synthesis using mechanical-chemical treatment with small additives of polar liquids. Physical and chemical properties of the synthesized catalysts were studied using sedimentation analysis, XRD, XPS, TEM and thermal analysis. The catalytic activity of the catalysts was examined in the course of dibenzothiophene hydrodesulphurization followed by the GC–MS analysis of the reaction products. Correlations between the catalytic activity and the methanol quantity added in the course of mechanical-chemical activation were established. The pathways of dibenzothiophene hydrodesulfurization reactions over the synthesized catalysts were proposed. Pour la première fois, des catalyseurs massiques à base de nano-crystallites MoS 2 ont été synthétisés à partir de molybdénite commerciale par activation mécanique en phase solide en une étape. Des liquides polaires ont été aussi additionnés en petites quantités comme adjuvants. Les propriétés physicochimiques des catalyseurs synthétisés ont été caractérisées par analyses par sédimentation, radiocristallographique et thermique, ainsi que par microscopie électronique à transmission et spectroscopie photoélectronique par rayons X. Les activités des catalyseurs dans une réaction modèle d’hydrogénolyse du dibenzothiophène ont été mesurées par analyse GC–MS. La corrélation entre l'activité catalytique et la quantité de methanol ajoutée au cours de l’activation mécano-chimique a été déterminée et discutée. Des hypothèses ont été émises sur les chemins réactionnels de l'hydrogénolyse des dibenzothiophènes à l’aide des catalyseurs synthétisés.

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

Investigation of co-effect of 12-tungstophosphoric heteropolyacid, nickel citrate and carbon-coated alumina in preparation of NiW catalysts for HDS, HYD and HDN reactions

Effects of activated carbon in a carbon-coated alumina (CCA) support, active phase morphology and its composition of Ni6-PW12S/Cx/Al2O3 catalysts in hydrotreating of model compounds were studied. The catalysts were synthesized using 12-tungstophosphoric heteropolyacid, nickel citrate and CCA and characterized with multiple methods: N2 physisorption, X-ray powder diffraction, H2 temperature programmed reduction, temperature-programmed desorption of ammonia, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The catalytic properties were determined using a fixed-bed microreactor in hydrotreating of dibenzothiophene, naphthalene and quinoline. It was found that with the increase of carbon content in the CCA up to 5wt.%, reducible reactivity, sulphidation degree, average length and stacking number of WS2 crystallites in the catalysts increased. Observed changes can be explained by weakening interaction between metal oxide species and carbon-coated support. Full promotion of the NiWS edges by nickel was achieved in the catalysts supported on the CCA with carbon content equal 0.3wt.% and more. Activities of the catalysts in dibenzothiophene hydrodesulphurization, naphthalene hydrogenation and quinoline hydrodenitrogenation were essentially depended on the carbon content in the CCA-support. Ni6-PW12S/C1/Al2O3 catalyst showed maximal conversions of the substrates in studied reactions. This result was achieved due to an optimal balance between turnover frequency value of the active sites and their content.

Effect of supports on the supported Ni2P catalysts prepared by the phosphidation using triphenylphosphine in liquid phase

Ni2P/Al2O3, Ni2P/MgAlO and Ni2P/MgO catalysts were prepared by the phosphidation of corresponding Ni/Al2O3, Ni/MgAlO and Ni/MgO with triphenylphosphine in liquid phase and compared with the previously reported Ni2P/SiO2 catalyst. It was found that the Ni2P/Al2O3 and Ni2P/MgAlO prepared by the pre-reduction at 723K followed by the phosphidation at 443K exhibited the high activities for the hydrotreating reactions. The two catalysts possessed small and homogeneously distributed Ni2P particles (6.5 and 8.3nm, respectively) with high CO uptakes (305 and 269μmol/g, respectively). After the hydrotreating reactions, the Ni2P phase in the catalysts remained and the sizes of Ni2P particles increased a little to 6.9 and 9.2nm, respectively. However, the CO uptakes on the used Ni2P/Al2O3 and Ni2P/MgAlO catalysts were greatly decreased to 68 and 74μmol/g, respectively, owing to the incorporation of S into the Ni2P surfaces. According to the CO uptakes on the used catalysts, it was found that the TOF values of hydrodesulphurization of dibenzothiophene on the Ni2P/Al2O3, Ni2P/MgAlO and Ni2P/SiO2 were similar, indicating that these supports did not affect the HDS activity, while the TOF values of hydrogenation of tetralin to decalin were significantly higher on Ni2P/MgAlO than on Ni2P/SiO2, indicating that Ni2P/MgAlO might be better than Ni2P/SiO2 for the hydrotreating reactions.

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.