Ti-modified alumina supports prepared by sol–gel method used for deep HDS catalysts

The typical physico-chemical properties and their hydrodesulfurization activities of NiMo/TiO₂-Al₂O₃ series catalysts with different TiO₂ loadings were studied. The catalysts were evaluated with a blend of two kinds of commercially available diesels in a micro-reactor unit. Many techniques including N₂-adsorption, UV–vis DRS, XRD, FT-Raman, TPR, pyridine FT-IR and DRIFT were used to characterize the surface and structural properties of TiO₂-Al₂O₃ binary oxide supports and the NiMo/TiO₂-Al₂O₃ catalysts. The samples prepared by sol–gel method possessed large specific surface areas, pore volumes and large average pore sizes that were suitable for the high dispersion of nickel and molybdenum active components. UV–vis DRS, XRD and FT-Raman results indicated that the presence of anatase TiO₂ species facilitated the formation of coordinatively unsaturated sites (CUS) or sulfur vacancies, and also promoted high dispersion of Mo active phase on the catalyst surfaces. DRIFT spectra of NO adsorbed on the pure MoS₂ and the catalysts with TiO₂ loadings of 15 and 30% showed that NiMo/TiO₂-Al₂O₃ catalysts possessed more CUS than that of pure MoS₂. HDS efficiencies and the above characterization results confirmed that the incorporation of TiO₂ into Al₂O₃ could adjust the interaction between support and active metals, enhanced the reducibility of molybdenum and thus resulted in the high activity of HDS reaction.     

Maya crude hydrodemetallization and hydrodesulfurization catalysts: An effect of TiO2 incorporation in Al2O3

Hydrotreating of Maya heavy crude oil over high specific surface area CoMo/TiO₂–Al₂O₃ oxide supported catalysts was studied in an integral reactor close to industrial practice. Activity studies were carried out with Maya crude hydrodesulfurization (HDS), hydrodemetallization (HDM), hydrodenitrogenation (HDN), and hydrodeasphaltenization (HDAs) reactions. The effect of support composition, the method of TiO₂ incorporation, and the catalyst deactivation are examined. Supported catalysts are characterized by BET specific surface area (SSA), pore volume (PV), pore size distribution (PSD), and atomic absorption. It has been found that sulfided catalysts showed a wide range of activity variation with TiO₂ incorporation into the alumina, which confirmed that molybdenum sulfided active phases strongly depend on the nature of support. The pore diameter and nature of the active site for HDS, HDM, HDN, and HDAs account for the influence of the large reactant molecules restricted diffusion into the pore, and/or the decrease in the number of active sites due to the MoS₂ phases buried with time-on-stream. The textural properties and hysteresis loop area of supported and spent catalysts indicated that catalysts were deactivated at the pore mouth due to the metal and carbon depositions. The atomic absorption results agreed well regarding the textural properties of spent catalysts. Thus, incorporation of TiO₂ with γ-Al₂O₃ alters the nature of active metal interaction with support, which may facilitate the dispersion of active phases on the support surface. Therefore, the TiO₂ counterpart plays a promoting role to HDS activity due to the favorable morphology of MoS₂ phases and metal support interaction.     

Catalytic activities of Co(Ni)Mo/TiO2–Al2O3 catalysts in gasoil and thiophene HDS and pyridine HDN: effect of the TiO2–Al2O3 composition

The effect of the TiO₂–Al₂O₃ mixed oxide support composition on the hydrodesulfurization (HDS) of gasoil and the simultaneous HDS and hydrodenitrogenation (HDN) of gasoil+pyridine was studied over two series of CoMo and NiMo catalysts. The intrinsic activities for gasoil HDS and pyridine HDN were significantly increased by increasing the amount of TiO₂ into the support, and particularly over rich- and pure-TiO₂-based catalysts. It is suggested that the increase in activity be due to an improvement in reducing and sulfiding of molybdena over TiO₂. The inhibiting effect of pyridine on gasoil HDS was found to be similar for all the catalysts, i.e., was independent of the support composition. The ranking of the catalysts for the gasoil HDS test differed from that obtained for the thiophene test at different hydrogen pressures. In the case of gasoil HDS, the activity increases with TiO₂ content and large differences are observed between the catalysts supported on pure Al₂O₃ and pure TiO₂. In contrast, in the case of the thiophene test, the pure Al₂O₃-based catalyst appeared relatively more active than the catalysts supported on mixed oxides. Also, in the thiophene test the difference in intrinsic activity between the pure Al₂O₃-based catalyst appeared relatively more active than the catalysts supported on mixed oxides. Also in the thiophene test, the difference in intrinsic activity between the pure Al₂O₃- and pure TiO₂-based catalysts is relatively small and dependent on the H₂ pressure used. Such differences in activity trend among the gasoil and the thiophene tests are due to a different sensitivity of the catalysts (by different support or promoter) to the experimental conditions used. The results of the effect of the H₂ partial pressure on the thiophene HDS, and on the effect of H₂S concentration on gasoil HDS demonstrate the importance of these parameters, in addition to the nature of the reactant, to perform an adequate catalyst ranking.     

Characterization and activity of Mo supported catalysts for diesel deep hydrodesulphurization

Various highly dispersed Mo supported catalysts with various carriers were prepared for deep hydrodesulphurization of diesel. The carriers included a high surface area and large pore volume γ-Al₂O₃, two types of meso-microporous composite molecular sieves prepared by incipient-wetness impregnation method. A new mesoporous MoSiO_x catalyst synthesized with in situ composite method was also studied. The hydrodesulphurization experiments were carried out in a micro-reactor over different catalysts including Mo supported series and a commercial catalyst. Spectroscopic techniques (FT-IR and UV–vis DRS) were utilized to determine the structure of MoO_x species. The catalyst characterizations of BET, XRD, FT-IR, UV–vis DRS and FTIR pyridine adsorption indicated that the existences of metal active component of Mo in the catalysts were highly dispersed nano MoO₃ clusters and the Mo series catalysts had high surface areas and plenty of large pores which were propitious to the diffusions of reactant and product molecules. Cat_NiMo exhibited the highest B/L acidity ratio and higher total concentration of Brønsted acid sites and Lewis acid sites, and its HDS activity also gave the highest in this study to produce a sulphur-free diesel, which was verified by the sulphur content in products analyzed by GC–MS methods.     

Modification of the preparation procedure for increasing the hydrodesulfurisation activity of the CoMo/γ-alumina catalysts

In this work we have examined whether the re-impregnation of CoMo/γ-alumina catalysts or the replacement of the conventional non-dry impregnation step by “equilibrium deposition filtration” (EDF) may be used for improving their surface characteristics and thus their catalytic activity.

Two samples were prepared. In the first sample (EDF) the molybdenum species were mounted by “equilibrium deposition filtration” whereas in the second sample these species were mounted by non-dry impregnation (NDI). In both cases the Co was deposited on the calcined Mo/γ-Al₂O₃ precursor solid by simple dry impregnation. An aliquot of each sample was impregnated again with an amount of pure water equal to its pore volume and then it underwent drying and calcination.

The catalysts prepared were characterized using N₂ adsorption measurements (BET), UV–vis diffuse reflectance spectroscopy (DRS), laser Raman spectroscopy (LRS) and NO chemisorption. The hydrodesulfurization (HDS) activities over the catalysts studied were determined using a continuous-flow tubular fixed-bed microreactor operating in a differential mode at atmospheric pressure.

It was confirmed that the replacement of the conventional impregnation by equilibrium deposition filtration results to catalysts with relatively high active surface and high portion of the well-dispersed octahedral cobalt and thus, to catalysts with 30% higher HDS activity. The re-impregnation resulted to partial dissolution and re-dispersion of the Mo and Co supported oxidic phases. Concerning the NDI catalyst re-impregnation resulted to an increase of the active surface and of the portion of the well-dispersed octahedral cobalt and thus to 25% higher catalytic activity. The opposite effects were observed for the EDF catalyst which exhibited almost 7% lower activity after re-impregnation.     

TiO2-coated on Al2O3 support prepared by the CVD method for HDS catalysts

Mo---Co or Mo---Ni catalysts supported on alumina (Al₂O₃) have been widely used for hydrodesulfurization (HDS) of heavy petroleum fractions. In order to enhance the catalytic activities for HDS, a composite type support (TiO₂-Al₂O₃) prepared by the chemical vapor deposition (CVD) method has been studied. We found that Mo catalyst supported on TiO₂-Al₂O₃ showed much higher catalytic activity for HDS of dibenzothiophene derivatives than the catalysts supported on Al₂O₃.     

Silica–alumina-supported transition metal sulphide catalysts for deep hydrodesulphurization

Deep hydrodesulphurization (HDS) of dibenzothiophene (DBT) and gas-oil has been carried out on amorphous-silica–alumina (ASA)-supported transition metal sulphides (TMS) under conditions which approach industrial practice. The activity and selectivity of the binary Ni-, Ru- and Pd-promoted Mo catalysts were compared with the monometallic ones (Ru, Ir, Pd, Ni, Mo on ASA). For both HDS of DBT and gas-oil, the observed activity trends were similar; thus, all catalysts were more active with model feed than with gas-oil, and less active than commercial CoMo/Al₂O₃. The binary catalysts showed larger activity than monometallic ones, with Ni–Mo catalyst being more effective than Ru–Mo or Pd–Mo. For Ni–Mo sample, the X-ray photoelectron and temperature-programmed reduction techniques confirmed that incorporation of Mo minimises metal–support interaction, although the formation of nickel hydrosilicate was not prevented. The consecutive impregnation of calcined Mo/ASA catalyst with precursor solution followed by calcination enhances molybdenum surface exposure in binary samples. As a consequence, the temperature of reduction of MoO₃ to molybdenum suboxides is decreased.     

Niobium sulfide as a dopant for Mo/TiO2 catalysts

Mo/TiO₂ catalysts were modified with Nb by two different methods, sol–gel and surface deposition, in order to study the effect of Nb incorporation on the thiophene HDS activity. The results show that the formation of Nb–Ti mixed oxides leads to catalysts with poor HDS activity while the deposition of Nb oxide species on the surface of TiO₂ leads to catalysts with activities larger than those of Mo/Al₂O₃ and Mo/TiO₂. This increase in activity was attributed to the formation of a larger population of Mo sulfur anionic vacancies when Nb was surface deposited on the TiO₂.     

A model catalyst approach to the effects of the support on Co–Mo hydrodesulfurization catalysts

Co–Mo model sulfide catalysts, in which CoMoS phases are selectively formed, were prepared by means of a CVD technique using Co(CO)₃NO as a precursor of Co. It is shown by means of XPS, FTIR and NO adsorption that CoMoS phases form selectively when the Mo content exceeds monolayer loading. A single exposure of MoS₂/Al₂O₃ to a vapor of Co(CO)₃NO at room temperature fills the edge sites of the MoS₂ particles. It is suggested that the maximum potential HDS activity of MoS₂/Al₂O₃ and Co–Mo/Al₂O₃ catalysts can be predicted by means of Co(CO)₃NO as a “probe” molecule. An attempt was made to determine the fate of Co(CO)₃NO adsorbed on MoS₂/Al₂O₃. The effects of the support on Co–Mo sulfide catalysts in HDS and HYD were investigated by use of CVD-Co/MoS₂/support catalysts. XPS and NO adsorption showed that model catalysts can also be prepared for SiO₂-, TiO₂- and ZrO₂-supported catalysts by means of the CVD technique. The thiophene HDS activity of CVD-Co/MoS₂/Al₂O₃, CVD-Co/MoS₂/TiO₂ and CVD-Co/MoS₂/Al₂O₃ is proportional to the amount of Co species interacting with the edge sites of MoS₂ particles or CoMoS phases. It is concluded that the support does not influence the HDS reactivity of CoMoS phases supported on TiO₂, ZrO₂ and Al₂O₃. In contrast, CoMoS phases on SiO₂ show catalytic features characteristic of CoMoS Type II. With the hydrogenation of butadiene, on the other hand, the Co species on MoS₂/TiO₂, ZrO₂ and SiO₂ have the same activity, while the Co species on MoS₂/Al₂O₃ have a higher activity.     

Preparation and characterization of nano-sized CoMo/Al2O3 catalyst for hydrodesulfurization

CoMo on Al₂O₃ catalyst prepared by spray pyrolysis method was found in the form of spheres of 0.5–1.2 μm, which consisted of tiny primary particles of ca. 10–20 nm diameter. The materials shows comparable activity to those of commercial catalysts in HDS of straight run gas oil, in particular, refractory 4,6-dimethyldibenzothiophene (4,6-DMDBT). Weaker interactions between CoMo and Al₂O₃ are suggested by temperature-programmed reduction (TPR), Raman spectroscopy, to give more active species than those over the impregnated catalysts. This accounts for its comparable activity in spite of its smaller surface area.     

Hydrodesulfurization activity of CoMo and NiMo supported on Al2O3–TiO2 for some model compounds and gas oils

Catalytic activities of Al₂O₃–TiO₂ supporting CoMo and NiMo sulfides (CoMoS and NiMoS) catalysts were examined in the transalkylation of isopropylbenzene and hydrogenation of naphthalene as well as the hydrodesulfurization (HDS) of model sulfur compounds, conventional gas oil (GO), and light cycle oil (LCO). Al₂O₃–TiO₂ supporting catalysts exhibited higher activities for these reactions except for the HDS of the gas oil than a reference Al₂O₃ supporting catalyst, indicating the correlation of these activities. Generally, more content of TiO₂ promoted the activities. Inferior activity of the catalyst for HDS of the gas oil is ascribed to its inferior activity for HDS of dibenzothiophene (DBT) in gas oil as well as in model solvent decane, while the refractory 4,6-dimethyldibenzothiophene (4,6-DMDBT) in gas oil as well as in decane was more desulfurized on the catalyst. Characteristic features of Al₂O₃–TiO₂ catalyst are discussed based on the paper results.     

Performance of CoMoS catalysts supported on nanoporous carbon in the hydrodesulfurization of dibenzothiophene and 4,6-dimethyldibenzothiophene

A new type of nanoporous carbon with a large surface area and mesoporosity was prepared and used as a support for a hydrodesulfurization (HDS) catalyst. The overall activity of CoMoS catalysts for the HDS of dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) is affected by the type of support used for preparing the catalyst and decreases in the order of CoMo/(nanoporous carbon)>CoMo/(activated carbon)>CoMo/Al₂O₃. The surface area of activated carbon is the largest among these three types of supports but is significantly lowered after metal loading during the preparation of the catalyst. On the other hand, the surface areas of the other two supports are largely preserved after metal loading. The intrinsic activity of the catalysts, estimated by dividing the overall HDS rate by the amount of NO adsorbed on the catalyst, shows a trend that is different from that for the overall activity, and follows the order of CoMo/(nanoporous carbon)≈CoMo/Al₂O₃>CoMo/(activated carbon). The low intrinsic activity of CoMo/(activated carbon) compared to that of the other two catalysts, particularly in the case of 4,6-DMDBT HDS, is obtained because the diffusion of reactants into the catalyst pores is significantly limited. This is not observed with other catalysts supported on nanoporous carbon and alumina. From the results of this study, we conclude that nanoporous carbon is a promising support for HDS catalysts, compared to conventional supports such as alumina and activated carbon, because it has a large surface area and a high mesoporosity, both of which are beneficial to the preparation of highly dispersed metal catalysts without significant pore blocking due to the dispersed metal particles.     

Sulfided Mo and CoMo supported on zeolite as hydrodesulfurization catalysts: transformation of dibenzothiophene and 4,6-dimethyldibenzothiophene

The hydrodesulfurization (HDS) of dibenzothiophene (DBT) and of 4,6-dimethyldibenzothiophene (4,6-DMDBT) was carried out on sulfided Mo and CoMo on HY catalysts, and also on sulfided Mo and CoMo on alumina catalysts (fixed bed reactor, 330°C, 3 MPa hydrogen pressure). On all the catalysts, the two reactants transformed through the same parallel pathways: direct desulfurization (DDS) leading to biphenyl-type compounds, and desulfurization after hydrogenation (HYD) leading first to tetrahydrogenated intermediates, then to cyclohexylbenzene-type products. However, additional reactions were observed with the zeolite-supported catalysts, namely methylation of the reactants, cracking of the desulfurized products, and, in the case of 4,6-DMDBT, displacement of the methyl groups and transalkylation. The global activity of Mo/zeolite in DBT or 4,6-DMDBT transformation as well as its activity for the production of desulfurized products (HDS) were much higher than those of Mo/alumina. On the other hand, cobalt exerted a promoting effect on the activity in the transformation of DBT or 4,6-DMDBT of all the molybdenum catalysts. However, this effect was much less significant with the zeolite support than with the alumina support, which indicated that the promoter was not well associated to molybdenum on the zeolite support. Therefore, the activity of CoMo/zeolite in the HDS of DBT was much lower than that of CoMo/alumina. On the contrary, in the case of 4,6-DMDBT CoMo/zeolite was more active in HDS than CoMo/alumina. This increase in HDS activity was attributed to the transformation of 4,6-DMDBT into more reactive isomers through an acid-catalyzed methyl migration. The consequence was that on the zeolite-supported catalyst 4,6-DMDBT was more reactive than DBT.     

Mixed oxides as a support for new CoMo catalysts

Interest in bifunctional catalysts, active in reactions such as hydrodesulphurisation (HDS) of hydrocarbon fractions, is growing in the last years. An improvement of CoMo/Al₂O₃ materials can be obtained by the introduction of other oxides during the sol–gel synthesis. This heavily affects the acid–base characteristics of the catalysts, while textural properties are less influenced. The catalytic performances change as well: a relationship between the density of acid sites and HDS activity has been found.     

Development of ultra-deep HDS catalyst for production of clean diesel fuels

Cosmo Oil has successfully developed a new CoMo HDS catalyst, C-606A, for production of ultra-low sulfur diesel fuels. This catalyst was prepared by an impregnation method using a solution containing Co, Mo, P, and citric acid on a HY-Al₂O₃. The resulting catalyst air-dried only without calcination. The HDS activity was measured with straight-run light gas oil feedstocks under industrial hydrotreating conditions. C-606A had a three times higher HDS activity compared with the conventional CoMoP/Al₂O₃ catalyst. Commercial operation with C-606A has successfully demonstrated high performance. This catalyst has superior activity, which enables <10-ppm sulfur content in products in a commercial hydrotreater designed to produce 500-ppm sulfur diesel fuels.     

Mesoporous molecular sieve MCM-41 supported Co–Mo catalyst for hydrodesulfurization of petroleum resids

In this work, we explored the potential of mesoporous zeolite-supported Co–Mo catalyst for hydrodesulfurization of petroleum resids, atmospheric and vacuum resids at 350–450°C under 6.9 MPa of H₂ pressure. A mesoporous molecular sieve of MCM-41 type was synthesized; which has SiO₂/Al₂O₃ ratio of about 41. MCM-41 supported Co–Mo catalyst was prepared by co-impregnation of Co(NO₃)₂·6H₂O and (NH₄)₆Mo₇O₂₄ followed by calcination and sulfidation. Commercial Al₂O₃ supported Co–Mo (criterion 344TL) and dispersed ammonium tetrathiomolybdate (ATTM) were also tested for comparison purposes. The results indicated that Co–Mo/MCM-41(H) is active for HDS, but is not as good as commercial Co–Mo/Al₂O₃ for desulfurization of petroleum resids. It appears that the pore size of the synthesized MCM-41 (28 Å) is not large enough to convert large-sized molecules such as asphaltene present in the petroleum resids. Removing asphaltene from the resid prior to HDS has been found to improve the catalytic activity of Co–Mo/MCM-41(H). The use of ATTM is not as effective as that of Co–Mo catalysts, but is better for conversions of >540°C fraction as compared to noncatalytic runs at 400–450°C.     

Deep HDS over NiMo/Zr-SBA-15 catalysts with varying MoO3 loading

In the present work, with the aim of searching for new, highly effective catalysts for deep HDS, a series of NiMo catalysts with different MoO₃ loadings (6–30 wt.%) was prepared using SBA-15 material covered with ZrO₂-monolayer as a support. Prepared catalysts were characterized by N₂ physisorption, small- and wide-angle XRD, UV–vis diffuse reflectance spectroscopy, temperature-programmed reduction, SEM-EDX and HRTEM, and their catalytic activity was evaluated in the 4,6-dimethyldibenzothiophene hydrodesulfurization (HDS). It was observed that ZrO₂ incorporation on the SBA-15 surface improves the dispersion of the Ni-promoted oxidic and sulfided Mo species, which were found to be highly dispersed, up to 18 wt.% of MoO₃ loading. Further increase in metal charge resulted in the formation of MoO₃ crystalline phase and an increase in the stacking degree of the MoS₂ particles. All NiMo catalysts supported on ZrO₂-modified SBA-15 material showed high activity in HDS of 4,6-DMDBT. The best catalyst having 18 wt.% MoO₃ and 4.5 wt.% NiO was almost twice more active than the reference NiMo/γ-Al₂O₃ catalyst. High activity of NiMo/Zr-SBA-15 catalysts and its evolution with metal loading was related to the morphological characteristics of the MoS₂ active phase determined by HRTEM.     

Performance of spent sulfide catalysts in hydrodesulfurization of straight run and nitrogen-removed gas oils

After the test run of several months two kinds of commercial catalysts (NiMo/Al₂O₃ and CoMo/Al₂O₃) were examined in hydrodesulfurization (HDS) of straight run (SRGO) and nitrogen-removed gas oils, at 340 °C under 50 kg/cm² H₂. Hydrogen renewal between stages was attempted to show additional inhibition effects of the by-products such as H₂S and NH₃. Spent NiMo/Al₂O₃ and CoMo/Al₂O₃ catalysts showed contrasting activities in HDS and susceptibility to nitrogen species, according to their catalytic natures, compared to those of their virgin ones. HDS over spent NiMo/Al₂O₃ was significantly improved by removal of nitrogen species, while that over spent CoMo/Al₂O₃ was much improved by H₂ refreshment. The activity for refractory sulfur species such as 4,6-dimethyldibenzothiophene was reduced more severely than that for the reactive sulfur species such as benzothiophenes over spent catalysts. The effects of both two-stage hydrodesulfurization and nitrogen-removal were markedly reduced over the spent NiMo when compared with those over virgin NiMo one. The acidity of the catalysts was correlated with the inhibition susceptibility by nitrogen species as well as H₂S and NH₃. Spent catalysts apparently lost their activity due to the carbon deposition, which covered the active sites more preferentially. The spent NiMo catalyst carried more deposited carbon with larger C/H ratio and nitrogen content. Higher acidity was found to be present on the NiMo catalyst, but this was greatly decreased by the carbon deposition. Additionally, the reactivity of nitrogen species in HDS was briefly discussed in relation to the acidity of the catalyst and its deactivation by carbon deposition.     

A comparative study for heavy oil hydroprocessing catalysts at micro-flow and bench-scale reactors

CoMo and NiMo catalysts were prepared and the catalytic activities were evaluated in fixed bed micro-flow and bench-scale reactors with different feed composition. Experiments were conducted at conditions close to those that exist in the industrial practice. Due to the different nature of the feeds, the conditions were varied with respect to both evaluation scales. The fresh and spent catalysts were characterized. Spent catalyst textural properties indicated that catalysts were deactivated and the surface area and pore volume dropped by 20–60%. The adsorption–desorption hysteresis of spent catalysts indicated that cylindrical pores are deactivated at the pore mouth and played an important role in modification by either closing one end of the pore or forming a narrow neck pore, which is indicative of the formation of “ink-bottle” type pores. Thus, the deposition of metal and carbon takes place preferentially at the pore entrance, which causes pore mouth plugging. These results are also supported by the SEM–EDAX analysis, where metal and carbon depositions are evident and taking place at the superficial region of a catalyst particle. The increase in absolute area of hysteresis is based on the catalyst's average pore diameter: the higher the average pore diameter, the lower the area of the spent catalyst. The activity and deactivation of the catalyst are discussed on the basis of catalyst porosity and deposited metal characterization. The composition of catalysts varies, considering two applications in a multi-reactor system: a CoMo catalyst for the first reactor, and a NiMo in the second reactor; the former is supported on γ-Al₂O₃ and the latter on TiO₂/Al₂O₃. As a comparison, the CoMo catalyst exhibited better hydrogenolysis while the NiMo catalyst showed better hydrogenation activity in both micro-flow and bench-scale reactors. It appears that there is a moderate effect of TiO₂ content in support on Ni and V hydrodemetallization (HDM) while hydrodeasphaltenization (HDAs) and hydrodesulfurization (HDS) activities were slightly improved when a partially hydrotreated feed, which contains more refractory compounds than virgin feedstock, was employed.     

磷添加方式对NiMo/Al2O3催化剂加氢脱硫性能的影响

采用分步浸渍法制备了不同磷添加方式改性的NiMo/Al₂O₃催化剂,在固定床微反装置上考察了该系列催化剂对焦炉煤气中噻吩加氢脱硫（HDS）性能的影响,采用BET、X射线衍射（XRD）、H₂程序升温还原（H₂-TPR）、NH₃程序升温脱附（NH₃-TPD）、C₄H₄S(H₂)程序升温脱附[C₄H₄S(H₂)-TPD]、X射线光电子能谱（XPS）、高清透射电镜（HRTEM）和拉曼（Raman）等分析手段对催化剂进行表征。结果表明,不同磷添加方式制备NiMo/Al₂O₃催化剂的HDS性能存在较大差异。其中,催化剂PNi-Mo/Al和PMo-Ni/Al表面弱吸附解离活性位增强,对焦炉煤气中噻吩有较好的低温加氢脱硫活性,以含292.5mg/m³噻吩的模拟焦炉煤气为原料时,PNi-Mo/Al在250℃下对噻吩的脱硫率达61%。对于PNi-Mo/Al和PMo-Ni/Al催化剂,先浸渍P、Ni或者P、Mo时,P优先和载体Al₂O₃作用,减弱了活性金属组分Ni、Mo与载体间的相互作用,而又防止Ni或者Mo与载体间相互作用过低而聚集,提高了Ni、Mo在载体表面的均匀分散,生成能够促进硫化形成Ⅱ型活性相Ni-Mo-S的NiMoO₄物种。NiMoO₄和MoO₃之间的协同作用提高了催化剂的硫化度,使HDS活性得以提高。