Catalytic esterification of bioglycerol to value-added products

The inevitably low value of bioglycerol has led to extensive investigations on glycerol conversion to value-added chemicals. This review focuses on the industrially important catalytic esterification of glycerol with oleic acid attributable to its high commercial value. Conventionally, the catalytic esterification of long-chain fatty acids with glycerol is operated at extreme operating conditions (homogeneous acid catalyst, high temperature, and intensive vacuum system). Because of these, rational design of reliable solid acid catalysts for water-sensitive esterification process is needed in order to enhance existing process condition. Up until now, the recent development of efficient and environmentally benign catalysts for esterification of glycerol with oleic acid has not been captured in any review. Therefore, the current literatures of catalytic esterification of glycerol with oleic acid and their affecting parameters are primarily discussed in this review. This review has shown that the hydrophobicity surface of catalysts is vital to boost up the reaction activity of polar glycerol and immiscible phase behavior of reactants. In addition, the concluding remarks for catalyst selectivity of glycerol monooleate, dioleate, and trioleate synthesis are presented. The paper also highlights the research gaps and future direction of this important research field.