Dual Sulfonic Acid Functionalized Heteropolyacid-Based Ionic Liquids for Esterification of Glycerol Toward Triacetylglycerol

Dual sulfonic acid functionalized heteropolyacid-based ionic liquids were synthesized, characterized and used as novel solid acid catalysts for selective esterification of glycerol with acetic acid toward fuel-additive triacetylglycerol (TAG). The results indicated that the as-prepared [BS 2 TMEDA]HPW 12 O 40 catalyst had the highest catalytic activity and selectivity to TAG compared with commercial H 3 PW 12 O 40 , H 2 SO 4 and Amberlyst-15 catalysts, which was attribute to its medium acidity of dual-SO 3 H groups and carbon chain length. The effects of reaction temperature, catalyst amount, acetic acid to glycerol mole ratio and reaction time on glycerol conversion and selectivity to TAG were also investigated. Under the optimized reaction condition, the glycerol conversion and selectivity to TAG reach 100% and 70.9%, respectively. Moreover, no significant loss in glycerol conversion and selectivity to TAG were observed after reused four recycles, showing favorable catalytic reusability and stability. Graphical Abstract