Study On The Esterification Of Acetic And Butylenes

This thesis studied the esterification of butenes with acetic acid over supported tungstophosphorous heteropoly acid catalyst (HPA) and strongly acidic cationic exchange resin, and investigated reaction conditions for the esterification. The results indicated that supported HPA and strongly acidic cationic exchange resin show good catalytic performance to the esterification, however, the catalytic activity of cationic exchange resin is higher than that of supported HPA obviously.Using supported HPA as the catalyst, the esterification of 2-butene with acetic acid is carried out in the high-pressure autoclave, the conversion of acetic acid reaches up to 33.5%, the selectivity of butyl acetate is above 96.0%, when the temperature is 110°C, the molar ratio of 2-butene to acetic acid is 2:1, and the reaction time is 7 hours. The adding of water to the reactants can promote the selectivity obviously.Using strongly acidic cationic exchange resin as the catalyst, the esterifications of acetic acid with butenes are carried out in the fixed- bed reactor, flowed-bed reactor or high-pressured autoclave, respectively. The results showed that high activity and selectivity of the esterification can obtain in the high-pressured autoclave. It is concluded from experimental results that the esterification of 1-butene with acetic acid consists with that of 2-butene, and the product of esterifications is same, i. e., sec-butyl acetate. It is known that the selectivity of sec-butyl acetate holds about 95.0% with 54.0% conversion of acetic acid, from the esterification of 2-butene or 1-butene with acetic acid, under the reaction conditions that the temperature is 110°C, the molar ratio of butene to acetic acid is 2:1 and the reaction time is 7 hours. It is also found that the oligomerization of isobutene occurs easily in the presence of acetic acid and acidic cationic exchange resin when temperature above 30°C, therefore, the esterification of isobutene with acetic acid should be carried out at the lower temperature. For example, the selectivity of ter-butyl acetate holds above 99.0% with 39.9% conversion of acetic acid, under the reaction conditions that the temperature is 20°C, the molar ratio of isobutene to acetic acid is 2:1 and the reaction time is 5 hours. Moreover, the preliminary mechanism of esterification of butenes with acetic acid over acidic cationic exchange resin has been studied, a possible mechanism is the electropholic addition of carbocation with acetic acid.