Mono- and Bimetallic Mo(W)S2/Al2O3 and Mo(W)S2/SBA-15 Hydrotreating Catalysts Based on SiMo12 and SiW12 Heteropoly Acids

Resumo

Mono- and bimetallic Mo(W)S₂ catalysts supported on γ-Al₂O₃ and SBA-15 have been prepared using the Keggin heteropoly acids (HPAs) H₄SiMo₁₂O₄₀ and H₄SiW₁₂O₄₀. The catalyst samples have been analyzed by temperature-programmed reduction with hydrogen, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy. Catalytic properties have been examined in the joint hydrotreating of dibenzothiophene and naphthalene on a flow-through unit. It has been shown that the use of mesoporous silica SBA-15 as a support can reduce the average length of Mo(W)S₂ particles from 4.9 to 3.7 nm and increase the average number of layers and the particle size of the active phase, changes that lead to an increase in catalytic activity by a factor of ~3 relative to the alumina-supported counterparts. The use of a mixture of SiMo₁₂HPA and SiW₁₂HPA for preparing MoW catalysts leads to a significant enhancement of catalytic activity, which is apparently due to the formation of mixed active sites.