Esterification catalytic over Imidazolium Ionic Liquid Modified salt of phosphotungstic Acid catalyst

A solid acid was prepared by the reaction of phosphotungstic acid (HPW)with 1-methy- limidazolium sulfobutyrolactone (MIMSB) and characterized by the methods of X-ray powder diffraction, FT-IR, potentiometric titration and SEM. Then the solid acid was employed for esterification to evaluate its acid-catalytic activity. Various reaction parameters, including catalyst dosage, reaction time, n-butanel/butyric acid molar ratio and reaction temperature were systematically examined. These results indicated that the prepared catalyst maintained the Keggin structure of the raw HPW, and had high acidity. The catalyst exhibited excellent catalytic activity in esterification of n-butyric acid and n-butanol.93. 4% conversion of n-butyric acid was obtained under the optimized reaction conditions. The catalyst also had good stability.