ABSTRACT
This chapter provides technological breakthroughs in biodiesel production, its possible feedstocks, and production technologies. It discusses transesterification of lipids from different feedstocks, in both chemically and lipase-catalyzed processes. The chapter presents the proposed employment of supercritical fluids in an integrated continuous extraction–reaction process. Supercritical transesterification is a one-step conversion process performed when the alcohol is in a supercritical state and in the absence of a catalyst. Transesterification of oils can also be catalyzed using acid instead of alkaline catalysts. A. Demirbas studied the transesterification of cotton, poppy, rapeseed, safflower seeds, and sunflower seeds, and reported that increasing reaction temperature to above supercritical had a positive influence on the conversion. Compared to catalytic reactions, supercritical reactions are fast and can achieve high conversions in a very short time. The affinity of the alcohol to water is high, which results in a stripping of the microlayer of essential water surrounding the lipase, which is required to maintain lipase conformation and catalytic activity.
