Influence of Preparation Method on the Catalytic Activity over AlCl3 Supported Catalyst for Alkylation Reaction of Thiophene and Olefins in Coking Benzene

AlCl3/gamma-Al2O3 and AlCl3/silica gel catalysts were respectively prepared by closely pressurized and atmospheric loading methods, and then used as the catalysts for the alkylation reaction between thiophene and 1-hexene in benzene. The influences of the preparation conditions of AlCl3 supported catalysts on the catalytic activity in the alkylation reaction were investigated. The results show that the catalysts prepared by the closely pressurized loading method present a higher catalytic activity than those by the atmospheric loading method. The ion chromatography, nitrogen adsorption, scanning electron microscope and X-ray diffraction techniques were used to characterize the composition and structure properties of catalysts. Compared with the atmospheric loading method, the closely pressurized loading method could effectively promote the active component amounts and its combined forms on the catalyst surface, and improve the pore structure of the support during the preparing processes. Among all catalysts, Si2H prepared with 2 g of AlCl3 loaded on 10 g of silica gel by the closely pressurized loading method has the best catalytic activity, which should be attributed to the appropriate loading amount and combined forms of AlCl3 in this catalyst, as well as the more suitable pore structure. The thiophene conversion rate of the Si2H catalyst can reach up to about 80% in the model coking benzene system and remains stable in five cycle experiments, where the thiophene concentration is 700 mg/L and the molar ratio of 1-hexene to thiophene is 6:1.