SO_4^(2-)/TiO_2固体超强酸的制备及用于催化酯化反应的研究

Preparation of Solid Superacid SO_4^(2-)/TiO_2 and Its Catalytic Application in Esterification

用两相滴定沉淀法制备了SO4（2-）／TiO2固体超强酸，透射电镜表征为超细粒子。分别用于氯乙酸酯、马来酸酯、丙烯酸酯的合成，具有较高的催化活性。对酯化反应的活性主要是B酸中心，其选择性要求B酸和L酸有一最佳协同作用。对该催化剂的使用寿命及再生进行了研究，认为不饱和羧酸在固体超强酸表面的强吸附及由此引起的失硫是催化活性降低的主要原因。

Solid superacid catalyst, SO_4^(2-) /TiO_2, is prepored by two-phase precipitation method,and used to synthesize isooctyl chloroacetate, dibutyl maleate and butyl acrylate. The catulytic activity in esterification relies on B acid site and selectivity is related to the ratio of B acid site to L acid site.The IR spectrum results show that the decrease of surface sulfur content caused by adsorption of unsaturated carboxylic acid on the surface of SO_4^(2-) /TiO_2, superacid leads to deactivition of catalytic activity. An optimum method to reactivate the superacid is also suggested.