(239e) Enzyme-Catalyzed Conversion of Glycerol to Glycerol Carbonate: Effect of Dialkyl Carbonate, Molar Ratios, Solvent Identity and Catalyst Loading On Reaction Rates, Conversions and Selectivity

As the biodiesel industry continues to grow, the question of what to do with the major side product, low-grade glycerol, has become increasingly important. Surplus glycerol offers a unique opportunity to produce biomass-derived raw materials and chemical intermediates that have previously been produced from petroleum. Conversion of this glycerol to a value-added product will also improve the economics of biodiesel production. One such product is glycerol carbonate, a versatile chemical that may be used as a solvent or additive by itself, or as a platform chemical in other industries. This project aims to convert glycerol to glycerol carbonate using a lipase as a biocatalyst.

Lipases, which are able to catalyze ester synthesis reactions in low water environments, were evaluated as biocatalysts for a reaction between glycerol and a dialkyl carbonate. Multiple lipases, dialkyl carbonate reactants, solvents, and reaction conditions were investigated. It was found that the conversion of glycerol to glycerol carbonate can be effectively catalyzed by Candida antarctica lipase B (Novozym 435). Although a solvent is not required for this reaction, it can enhance lipase activity. The rate of reaction as well as the product specificity differs for different dialkyl carbonate substrates. The effects of reaction water content, lipase loading, and reactant molar ratios were also investigated. Under the right conditions, nearly 100% glycerol conversion was achieved after 12 hours of reaction time, with the primary product being glycerol carbonate. The effects of these various reaction conditions on lipase activity and product selectivity will be presented.