Preparation of aluminum and gallium-promoted SO_4~(2-)/ZrO_2 and its catalytic activity for esterification

Gallium and aluminum-promoted SO~(2-)_4/ZrO_2 catalysts were prepared by the steps of precipitation,reflux,wetness impregnation and calcinations.The surface property of catalyst was studied by N_2(adsorption)(BET),TG-DTG and chemical analysis.The results showed that addition of gallium or aluminum increased the decomposition temperature of sulfate groups so that it had a positive effect on retaining surface sulfate.The catalytic activity was measured by the ester yield obtained from the reaction of acetic acid with n-butanol.The experiment results showed that the Al and Ga promoted catalysts exhibit excellent catalytic activity and stability at 600 ℃.The esterification rates amounts to 98.8% and 97.1%(respectively) 105~110 ℃.In particular,the catalysts have good reusing property.The esterification rate still remained over 90% even after four times repeatedly using the catalysts.