Esterification of By-products of Biodiesel Fuel Production with Methanol and Technical Glycerol Using Biocatalysts

Abstract

In production of biodiesel fuel several by-products, such as glycerol and free fatty acids, are formed. The options for applying biochemical methods to process these by-products have been studied. The process of free fatty acid esterification with methanol using Lipozyme RM IM is to be performed in steps, with gradual addition of methanol into the reaction media. In 4 hours of a multi-step process it is possible to esterify up to 60% of free fatty acids. Novozym 435 is not inactivated by methanol, therefore, esterification with methanol of free fatty acids can be performed in one step. Free fatty acid esterification with glycerol is slowed down by admixtures present in by-products of biodiesel fuel production. After 7 hours of reaction, only 82.2% of free fatty acids react when using Novozym 435, and only 41.7% do in a case of Lipozyme RM IM, whereas in the case of esterification of pure oleic acid with pure glycerol the amounts reach 97.7% and 84.8%, respectively. Efficiency of ferment preparation Novozym 435is almost twice higher compared to Lipozyme RM IM. However, taking into account the prices of ferment preparations, it is possible to conclude that Lipozyme RM IM has future prospects in industrial synthesis.