1-丁基-3-甲基咪唑磷钨酸盐的制备及其对酯化反应的催化性能

以溴化1-丁基-3-甲基咪唑盐(bmim]Br)和磷钨酸(H3PW12O40)为原料制备了1-丁基-3-甲基咪唑磷钨酸盐(bmim]3PW12O40)催化剂,并用傅里叶变换红外光谱、热重分析-差示扫描量热法、正丁胺电位滴定及元素分析等技术对催化剂进行了表征,考察了催化剂对乙醇与乙酸酯化合成乙酸乙酯反应的催化活性.结果表明,bmim]3PW12O40中有3个结晶水,并保持有H3PW12O40的Keggin结构和酸强度,bmim]3PW12O40的酸量明显少于H3PW12O40的酸量.在乙醇与乙酸酯化合成乙酸乙酯反应中,bmim]3PW12O40催化剂具有较高的催化活性和较好的重复使用性能.

Preparation of 1-Butyl-3-methylimidazolium Dodecatungstophosphate and Its Catalytic Performance for Esterification of Ethanol and Acetic Acid

A 1-butyl-3-methylimidazolium dodecatungstophosphate (bmim]3PW12O40) catalyst with high resistance to water was prepared from 1-butyl-3-methylimidazolium bromide (bmim]Br) and dodecatungsto-phosphoric acid (H3PW12O40). The catalyst was characterized by means of Fourier transform infrared spectroscopy, thermogravimetry-differential scanning calorimetry, n-BuNH2 potentiometric titration, and elemental analysis. Its catalytic activity for esterification of ethanol and acetic acid to ethyl acetate was measured. The results showed that there were three crystal-water molecules in the bmim]3PW12O40 catalyst, and it preserved the primary Keggin structure and acid strength of H3PW12O40. The acid amount of the bmim]3PW12O40 catalyst was less than that of H3PW12O40. The bmim]3PW12O40 catalyst exhibited higher catalytic activity and reusability in the esterification of ethanol and acetic acid to ethyl acetate.