Sulfonated carbon: synthesis, properties and production of biodiesel

Heterogeneous acid catalysts have been reported as potential substitutes of homogeneous catalysts for biodiesel production, mainly due to their abilities to simultaneously perform esterification and transesterification reactions, besides the ease of separation and recovery from the reaction medium, making it possible its reuse in other cycles. Different materials can be applied as heterogeneous catalysts, and sulfonated carbons present characteristics that qualify them as prominent catalysts. This review article reports the state-of-the-art regarding the sulfonated carbons for biodiesel production. Carbon-based materials can be obtained from several precursors, which makes them environmentally and economically viable. The parameters of the sulfonation process are directly related to the acid density and consequently to the final biodiesel yield. Sulfonated carbons can be successfully applied as a catalyst in the synthesis of biodiesel from different oils and its catalytic activity is similar or superior to the other heterogeneous acid catalysts.