| With Green Chemistry being advocated, the brand-new concept of green catalyst has been brought forward recently. Solid superacid has many advantages such as high activity, well selectivity, and no corrosiveness, no pollution, and liability to be separated from the reaction material. It is a green industrial catalyst that is helpful to recycling and possesses wide prospect of application. Thus, research on solid superacid has drawn more and more attention in industrial catalyst field.In this paper, we recounted the recent development of solid supeeracids and their appliance in esterification. The SO42-/TiO2-SiO2 solid superacid catalyst was prepared by sol-gel method;its catalytic activity was investigated to synthesis of methyl acetate. The reactive condition of catalyst was optimized by orthogonal method. The acid strength and structures of solid superacid catalyst was research. The whole process is divided into three parts which are as follow:1) The examination of catalytic preparation and property. By orthogonal experiments, we have educed SO42-/TiO2-SiO2 catalytic best preparative conditions: the amount of tetrabutyl titanate is A1 (0.5g), the amount of vitriol is B3 (1.5ml), the temperature of calcine is C1 (400 ℃), the temperature of dripping tetrabutyl titanate is D2 (20℃) . The temperature of calcine is the maximal influencing factor for catalytic activity of catalysts.2) We have investigated catalytic physical properties by song analytical methods, such as IR, TG and Hammett indicator. Then we have drawn a conclusion: the maximal acid strength of SO42-/TiO2-SiO2 solid superacid catalyst is -12.70. The acid centre mode of SO42-/TiO2-SiO2 is chelate structure.3) By discussing the mechanism of catalytic losing activity. We have concluded that the main losing activity reason of SO42-/TiO2-SiO2 solid superacid catalysts used in synthesis of methyl acetate is the accumulated carbon of catalytic surface and the loss of SO42-.
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