Operation of Bench Plants Producing Racemic Lactic Acid and Lactide Isomers from Glycerol, a by-product of Biodiesel Fuel Production Process

We developed a novel production method for stereoblock poly(lactic acid) (sb-PLA) from glycerol that is a by-product of biodiesel fuel (BDF) production process. It includes the novelties of (1) the conversion of glycerol into racemic lactic acid by alkaline hydrothermal reaction and (2) the stereoselective polymerization of lactide isomers by using an achiral homosalen-aluminum complex as a catalyst to synthesize sb-PLA. For practical use of these novel methods, we have constructed bench plants that can produce mixture of lactide isomers from glycerol. The throughput capacity of glycerol in the bench plant is about 50 tons/year. The bench plant was controlled stably for ∼100 hours, and it was confirmed that racemic lactic acid and then the mixture of lactide isomers were produced by the bench plants.