Tire-derived carbon for catalytic preparation of biofuels from feedstocks containing free fatty acids

[Display omitted] •Tire-derived carbon were functionized with catalytically active species.•The catalysts were effective in converting free fatty acids to biofuels.•The catalysts could be reused without significant loss of catalytic activity. The utilization of waste feedstocks rich in free fatty acids (FFAs) improves biofuel production on the basis of economics and sustainability. However, converting these feedstocks to usable biofuel poses inherent problems in terms of the FFA to biofuel conversion yield and the catalyst lifetime. Here, we report novel ferric sulfate impregnated carbon derived from waste tires as highly active catalysts for FFA to biofuel conversion. Our approach takes advantage of facile synthesis methods involving sonication and dehydration processes to create materials that are useful for the efficient catalytic conversion of FFAs to advanced biofuels. Esterification of FFAs to fatty acid methyl esters was achieved at 65 °C and atmospheric pressure with >98% yield even in the presence of triglycerides. These catalysts maintained similar activity after four successive uses, which indicates that the active catalytic sites are effectively supported by the three-dimensional meso/microporous architecture of the tire-derived carbon.