Cheaper Biodiesel, Thanks To U.S. Research

05 July 2007

Producing biodiesel from cheap feedstocks could become easier and more environmentally friendly thanks to scientists in the US.

Biodiesel, the biodegradable and renewable alternative to fossil fuels, is made by the alkali-catalysed transesterification of oil or fat. Readily available sources of oil or fat, such as used cooking oils, could be a cheap source of feedstock for biodiesel production. But these oils tend to contain high levels of free fatty acids, which must be removed before transesterification. This usually involves a pre-treatment step with an acid catalyst, which requires large amounts of base to neutralise the catalyst once the fatty acids have been removed.

Polymer-supported diarylammonium catalysts are highly effective in reducing the free fatty acid content in oils.

Wenbin Lin at the University of North Carolina, Chapel Hill, and colleagues have come up with a potential solution. The researchers have shown that polymer-supported diarylammonium catalysts are highly effective in reducing the free fatty acid content in oils by esterification of the free fatty acid to fatty acid methyl esters. The catalysts can easily be removed from the treated oil and re-used.

'This technology can be more environmentally friendly than existing technology using liquid acid catalysts,' said Lin.

Lin's team is now working on improving the process. 'More stable and reusable catalysts need to be identified and developed for this technology to be commercially viable,' added Lin.

Chemical Science, July 5, 2007