Preparation of AlCl3/silica gel catalyst for simultaneously removing thiophene and olefins from coking benzene by inclosed grafting method

AlCl3/silica gel catalysts were prepared by inclosed grafting method in the autoclave and their catalytic activities for alkylation reaction of thiophene with olefins in benzene were studied. The gas chromatograph and chromatography–mass spectroscopy were used to quantitatively determine the thiophene in benzene and qualitatively measure the reaction products, respectively. XPS, SEM, EDX and N2 adsorption techniques were used to characterize the physical and chemical properties of catalyst samples. The results show that AlCl3 can be effectively anchored by reacting with the silanol groups on silica gel surface to form the Six(OH)y − aOaAlCl(3 − a) species and the prepared AlCl3/silica gel catalyst possesses the significant activity for the alkylation reaction of thiophene and olefin. The preparation conditions, such as mass ratio of AlCl3/silica gel support, grafting temperature and time, and thermal treatment temperature of silica gel, have an important role on the content and distribution of active component over silica gel support, and thus affect the catalytic activity. The optimum preparation conditions of AlCl3/silica gel catalyst are that AlCl3 is grafted on silica gel support, which has been thermally treated at 400 °C for 3 h, and at 180 °C for 4 h with the mass ratio of 0.20 for AlCl3/silica gel support. The loading ratio of AlCl3 on silica gel can reach about 64 wt.% and the optimal conversion rate of thiophene in benzene is 94.23% when the ratio of liquid to catalyst is 20 mL/g.

• Preparation method of AlCl3/silica gel catalyst by closed grafting was explored.
• Catalyst shows high alkylation activity of thiophene and olefins in benzene.
• Grafting manner between AlCl3 and silica gel support was discussed in detail.
• Alkylation products of thiophene and olefins were analyzed by results of GC/MS.