Liquid Phase Alkylation of Benzene with Ethylene Catalyzed by Supported 12-Tungstophosphoric Acid

Supported 12-tungstophosphoric acid was prepared by incipient impregnation of spherical silica gel with aqueous solution of 12-tungstophosphoric acid H 3PW 12 O 40 · n H 2O.Alkylation of benzene with ethylene catalyzed by supported 12-tungstophosphoric acid under liquid phase conditions has been studied,including the effects of pretreatment temperature of catalyst,reaction temperature,water content in benzene,molar ratio of benzene to ethylene in the feed,and weight hourly space velocity of feed on ethylene conversion and alkylation selectivity.The catalytic activity of catalyst is associated with its acidity,which is controlled by the pretreatment temperature and water content in benzene.The catalyst is very active and selective as long as reaction temperature is higher than 140 ℃.Furthermore,molar ratio of benzene to ethylene and WHSV of benzene greatly affect the conversion of ethylene and selectivity to ethylbenzene.Preferred reaction conditions are determined: reaction temperature 160～240 ℃,total pressure 2～3 MPa,molar ratio of benzene to ethylene 12～24,WHSV of benzene 5～10 h -1 ,and water content in benzene 20～50 g/m 3 Under such conditions,conversion of ethylene is 100%,selectivity to ethylbenzene is greater than 90%,and selectivity of ethylation is greater than 98%.