Feedstocks, catalysts, process variables and techniques for biodiesel production by one-pot extraction-transesterification: a review

Biodiesel is a sustainable alternative to petroleum diesel. The main bottlenecks in the commercialization of biodiesel are production costs and suitable industrial techniques to process feedstocks. This can be solved by one-pot extraction-transesterification of cheap, low-quality feedstocks. Here we review one-pot extraction-transesterification using agricultural seed crops, oleaginous microbial biomass and biological refuse, with focus on catalysis. Catalysts such as acetyl chloride, sodium hydroxide, sulphonated rice husk and calcium oxide have shown to be efficient with conversion in the range of 95-100%. We present intensification techniques such as microwave irradiation, ultrasonication, coupled microwave and ultrasound, thermally assisted and solvothermal processes.