Friedel-Crafts Acylation of Furan: Development of A Green Process Using Chromium-exchanged Dodecatungstophosphoric Acid: Effect of Support, Mechanism and Kinetic Modelling

Abstract

The Friedel-Crafts acylation of furan with acetic anhydride to produce 2-acyl furan is industrially important. With an aim of replacing the highly polluting process, it this study, supported but modified heteropoly acids were used. Metal exchanged dodecatungstophosphoric acid (DTP) was loaded on three different supports and its effect on acylation was evaluated. Thus, chromium exchanged DTP was supported on K-10, SiO2, and ZrO2 using the incipient wetness impregnation method. 20% w/w Cr0.66-DTP/K-10 having the best activity for the acylation of furan with acetic anhydride was chosen for full characterization and reaction kinetics. Under optimized condition, the catalyst to furan ratio was 9.6%, significantly less as per prior art, which gave 88% conversion with 100% selectivity. The prepared catalysts were characterized by sophisticated techniques, namely, XRD, FT-IR, SEM, NH3-TPD, TGA, and BET. The Eley-Rideal mechanism was found to fit the kinetic data. The activation energy was found to be 18.03 kcal/mol. The reaction is green and clean as no chlorinated chemicals, reagents, and catalysts were used.