Abstract: 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.

Key words: bio-oil, ion exchange resin, modification, zinc chloride, microwave esterification