ZnCl2改性离子交换树脂的制备及其催化乙醇和乙酸酯化反应性能

 采用离子交换法制备了 ZnCl2 改性的阳离子交换树脂催化剂, 考察了 ZnCl2 浓度、离子交换时间和溶剂等对催化剂催化乙酸和乙醇微波酯化反应性能的影响. 结果表明, 以去离子水为溶剂, 以 0.15%ZnCl2 溶液进行离子交换 30 h, 所得催化剂的性能较好. 采用酸碱滴定法、紫外-可见光谱、傅里叶变换红外光谱、扫描电镜和 N2 吸附脱附等手段对催化剂进行了表征. 结果表明, 改性后的催化剂 H+交换量约为原来的 1.5 倍, 表面酸强度增加; 树脂骨架结构变化不大; 紫外吸收峰发生蓝移, 吸收强度减小; 比表面积略有减小; 催化剂在含水体系中表现出较高的催化活性, 且重复使用性能大大提高.

Preparation of ZnCl2-Modified Ion Exchange Resin and Its Catalytic Activity for Esterification of Ethanol and Acetic Acid under Microwave

An ion-exchange method was used to prepare a ZnCl2-modified ion exchange resin. Several factors such as impregnation liquid con-centration, ion-exchange time, and solvent used in the preparation were examined. Optimal preparation conditions for the ZnCl2-modified ion exchange resin included the use of deionized water as solvent, 0.15% concentration (mass fraction) of the ZnCl2 solution, and ion-exchange time of 30 h. The H+ exchange capacity of the ZnCl2-modified ion exchange resin was investigated by acid-base titration. UV-Vis spectros-copy, Fourier transform infrared spectroscopy, scanning electron microscopy, and N2 adsorption were used to characterize the catalyst. Gas chromatography was used to determine the catalyst activity for the esterification of ethanol and acetic acid under microwave. The acid strength and catalytic activity of the ion exchange resin were improved after being modified by ZnCl2, and the H+ exchange capacity of the modified catalyst is about 1.5 times that of the original one. Moreover, the skeleton structure of the modified resin has not changed. Only a small blue shift and reduction of the absorption intensity can be observed on the corresponding UV absorption peak, and the BET surface area decreases slightly. The ZnCl2-modified catalyst showed a higher reactivity in the water system and a better repeatability as compared to the unmodified one.