Preparation of 1-butyl-3-methylimidazolium dodecatungstophosphate and its catalytic performance for esterification of ethanol and acetic acid

Abstract

1-Butyl-3-methylimidazolium dodecatungstophosphate catalyst ([bmim]3PW12O40) with high water tolerance was prepared from 1-butyl-3-methylimidazolium bromide ([bmim]Br) and phosphotungstic acid (H3PW12O40). The catalyst was characterized by means of Fourier transform infrared spectroscopy, thermogravimetry-differential scanning calorimetry, n-BuNH2 potentiometric titration, elemental analysis and so on. Its catalytic activity for esterification of ethanol and acetic acid to ethyl acetate was measured. The results show 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 [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.