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High surface area, ordered mesoporous SBA-15 and Al-SBA-15 were synthesized using published procedures and used as support for Mo and W catalysts promoted with Co and Ni. The molybdenum loading was varied on Al-SBA-15 from 2 to 12 wt %, and Co or Ni loading was varied on 8%Mo/Al-SBA-15 from 1 to 5 wt %. The support and catalysts were characterized by X-ray diffraction (XRD), Barett−Joyner−Halenda (BJH) pore-size distribution, Brunauer−Emmett−Teller (BET) surface area, Fourier transform infrared (FT-IR), temperature-programmed reduction (TPR), and oxygen chemisorption. The characterization results indicated that hexagonal mesoporous structure is retained on Mo, CoMo, and NiMo catalysts. The TPR studies indicated that there are significant differences in Mo reducibilities and reducible species that are present on SBA-15 and Al-SBA-15 supported catalysts. The catalytic activities for thiophene, hydrodesulfurization (HDS), and cyclohexene hydrogenation (HYD) were carried out as a function of Mo and CoMo or NiMo loadings at 400 °C on sulfided catalysts. The results indicated that the molybdenum is dispersed well up to 8% Mo loading and 8 wt % loading is optimum for catalytic activities. Oxygen chemisorption correlated well with catalytic activity. The reducibilities of the catalysts and their relation to catalytic activities are discussed. A comparison of the physicochemical properties and catalytic activities of Mo and W catalysts supported on SBA-15 and Al-SBA-15 is made.

Catalysts containing 2−12 wt % Mo and 1−5 wt % Co or Ni were prepared using commercial H-β-zeolite as a support. The support as well as various catalysts were characterized by X-ray diffraction (XRD), BET surface area, temperature-programmed reduction (TPR), and in situ oxygen chemisorption in the sulfided state. The XRD studies indicated that the crystallinity of β-zeolite decreases rapidly at higher loadings of molybdenum, and there is no evidence for the presence of crystalline Mo phases below 10 wt % Mo loading. At higher loadings, however, MoO3/MoS2 may be present in small quantities. The BET surface area analysis indicated that molybdenum is well-dispersed up to 6 wt % Mo loading in both oxide and sulfide states. The oxygen uptakes increased up to 6 wt % Mo and then decreased at higher loadings. The crystallite sizes evaluated by oxygen chemisorption are small, indicating that MoS2 is well-dispersed on the support up to 6 wt % Mo. The TPR results indicated that a Co or Ni promoter helps decrease the temperature of the Mo reduction. TPR results indicated that two molybdenum phases with differing reduction behavior exist before and after 6% Mo loading. Catalytic activities for HDS, HYD, and HCK followed the same trend as oxygen uptake. A comparison with γ-Al2O3 indicated that the β-zeolite support imparts superior HYD activities in Mo, CoMo, and NiMo catalysts. Y-zeolite catalysts exhibit higher HDS activities but lower HYD activities than β-zeolite-supported catalysts.

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H-β-zeolite-supported tungsten sulfide catalysts with W loading varying between 10 and 25 wt % were prepared and characterized by BET surface area, pore size distribution in micro-and mesopore regions, in situ microcalorimetric ammonia adsorption, and oxygen chemisorption at low temperatures on sulfided catalysts. The thiophene HDS, cyclohexene hydrogenation (HYD), and cumene hydrocracking (HCK) reactions were carried out on sulfided catalysts. The differential heat curves and acid strength distributions indicated that sulfiding and WS 2 content have a profound influence on the acidic properties of these catalysts. It was concluded that zeolite and WS 2 both contribute to the acidic properties of the catalysts. There exists a correlation between strong acid sites and HCK activity. The relation between initial heat of adsorption and HCK activity suggested that acid sites g100 kJ/mol are involved in cumene hydrocracking on these catalysts.