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

[Display omitted] •Heterogeneous catalysts in the esterification of levulinic acid is reviewed.•Effect of esterification reaction conditions and catalytic results are summarized.•Levulinic esterification reaction mechanisms over various catalysts are reviewed.•Designing and developing more selective, active and durable catalysts are discussed.•Challenges of solid catalysts and future prospects of alkyl levulinates are discussed. 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.