22.7 research highlights 416 MH

Biodiesel is an alternative fuel derived from fatty acids in vegetable oils or animal fats. Because it contains almost no sulphur, it burns more cleanly than conventional diesel. However, the chemical reaction that breaks down the fatty acids into fuel relies on an aqueous alkali catalyst such as sodium hydroxide, making the product difficult to separate from the reaction mixture. Robert S. Watkins et al. now unveil a solid catalyst for this reaction that works just as well as a conventional catalyst, yet allows much easier separation of products. Their experiments used starting materials that contain shorter carbon chains than those found in vegetable oils, as a simpler model system for screening potential catalysts. The authors achieved a 100% yield of the product using a calcium oxide catalyst loaded with 1.23% (by weight) lithium nitrate. The catalyst could be easily filtered from the reaction mixture, and recycled with minimal loss of activity. This could open up the possibility of synthesizing biodiesel as a continuous process, rather than in batches. Mark Peplow