Enzymatic processing of renewable glycerol into value-added glycerol carbonate

Increased production of biodiesel has led to excess glycerol production worldwide, which has resulted in a significant drop in glycerol prices. Glycerol carbonate is a multifunctional compound used as chemical intermediates, solvents, additives and monomers. In this study, the enzymatic synthesis of glycerol carbonate from glycerol and a dialkyl carbonate was investigated. Glycerol carbonate was formed when reacting glycerol with dimethyl carbonate, diethyl carbonate or dibutyl carbonate in the presence of Candida antarctica lipase B (Novozym 435), using tert-butanol as a solvent. Nearly 100% glycerol conversion was reached after 12 h, with glycerol carbonate being the primary product. The effects of reaction parameters including solvent choice and biocatalyst loading were also examined. The highest activity was found at restricted water conditions and when using tert-butanol as a solvent.