Since recent past the research on biodiesel production and processing has got high momentum as evidenced from the large number of publications and patents on the subject. Many novel and improved protocols based on chemical, physical, and biological approaches have been reported that addresses the critical issues related to biodiesel production, recovery, purification, and associated recovery of high valued secondary products. Biodiesel typically comprises lower alkyl fatty acid (chain length C14-C22) esters of short-chain alcohols, primarily, methanol or ethanol. Various methods, such as pyrolysis, micro-emulsification, ozonization, ultrasonication, and transesterification have been reported for the production of biodiesel from vegetable oil. Among these, transesterification is appeared as attractive and widely accepted technique. This transesterification is mostly done chemically or enzymatically using lipase as biocatalyst. Lipase catalysis has received increasing attention due to its certain advantages over the conventional chemical catalysis. However, poor operational stability and low focus on the application of lipase for the biodiesel production are some of the important obstructing factors that impede the progress of the enzyme-based process. In addition to the transesterification step, separation of the ester from the reaction mixture, purification of the ester and glycerol, maintenances of appropriate fuel quality standards of the biodiesel (or blend stocks) as per specification for the particular nation, storage and stabilization are ascribed as the critical steps having immense effect on the successful implementation of biodiesel production and processing. In this review, the authors emphasise the important patents developed in the last few years that contribute to mitigate the major technological challenges on biodiesel production and processing.
Biodiesel, transesterification, catalysts, lipase, storage, processing
Centre for Energy,Department of Biotechnology, Indian Institute of Technology Guwahati,Guwahati-781039.