Recent advances in heterogeneous catalysts for the synthesis of alkyl levulinate biofuel additives from renewable levulinic acid: A comprehensive review

Abstract

Alkyl levulinates are one of the most desirable and promising compounds for biofuel production, since they have been identified as one of the prospective fuel-blending chemicals. So far, numerous types of heterogeneous acid catalysts have been used for the synthesis of alkyl levulinates. In this regard, designing and engineering new catalysts for upgrading levulinic acid into biofuel additives have received remarkable attention by global researchers and it has always been a challenging task. The aim of this article is to review the most six relevant heterogeneous catalysts, namely zeolites, mesoporous silicas, carbonaceous materials, metal organic frameworks (MOFs), ion exchange resins and enzymatic catalysts, in the esterification of levulinic acid. This review also outlooks the catalyst preparation, structural and surface modification, aspects of esterification reaction and reaction mechanisms involved. Subsequently, the challenges and future prospects in this field are also discussed.