Lactic Acid Production as a New Approach for Exploitation of Glycerol

Electrochemical oxidation of glycerol, the principal by-product of biodiesel production, generally leads to multicomponent product mixtures. The aim of this project was to investigate the feasibility of a technical process for electrochemical oxidation of crude glycerol followed by catalytic conversion of the intermediates dihydroxyacetone and glyceraldehyde to lactic acid. Partial electrochemical oxidation of glycerol with diamond coated electrodes was assumed to provide a route for converting glycerol to dihydroxyacetone and glyceraldehyde. Through instant selective conversion of dihydroxyacetone and glyceraldehyde to lactic acid the major disadvantage of electrochemical conversion, cleavage of intermediates, may be limited. Continuous separation of lactic acid from the electrolyte enables acceptable current efficiency as well as yield of products. Reactive extraction with phosphoryl compounds has proven applicable for the isolation of lactic acid from the electrolyte. Based on the results of these investigations a complete process for lactic acid production from glycerol was designed.