Isobutane/butene alkylation over supported heteropoly acid catalysts : I. Influence of the structure of silica

Catalysts consisting of heteropoly acids (HPAs) supported on different silica and mesoporous molecular sieves have been prepared by impregnation and the sol–gel method, respectively, and their catalytic behavior in fixed‐bed alkylation of isobutane with butene has been investigated. The activity, selectivity and stability of the supported‐HPA catalysts could be correlated with the surface acidity of the catalysts, the structure of supports as well as the time on stream (TOS). In the fixed‐bed reactor, the acidity of the heteropoly acid is favorable to the formation of dimerization products (C8=); especially, the pore size of supports was seen to have an important effect on activity and product distribution of the catalysts. Contrary to the traditional solid‐acid catalysts, the supported‐HPA catalysts own an excellent stability for alkylation, which makes it possible for these supported catalysts to replace the liquid‐acid catalysts used in industry.