Upgrading of biomass-derived furanic compounds into high-quality fuels involving aldol condensation strategy

Furanic derivatives represent important platform molecules in biomass valorization and occupy a significant position in biorefinery system. A wide range of hydrocarbon fuels are accessible from furanic compounds via C-C elongation strategies, particularly aldol condensation reactions. The present contribution aims at providing an overview on the recent advances in synthesis of fuel precursors from bio-based furanic derivatives via aldol condensation approach, with emphasis on several renowned furanic derivatives such as furfural, 5-hydroxymethylfurfural, levulinic acid and cyclopentanone. Progress with the state-of-the-art heterogeneous catalysts, including base, acid and acid-base bifunctional catalysts, applied in aldol condensation of bio-based furanic derivatives to produce fuel precursors is systematically summarized. Furthermore, the influence of catalysts structure on catalytic performance, corresponding reaction pathways/mechanism and catalysts stability are in detail discussed. In addition, recent achievements in catalytic upgrading of the resulting condensation adducts into hydrocarbon fuels are also described. This review paper provides us a guideline in the selective conversion of furanic derivatives to high-quality fuels and value-added products, which would inspire future research efforts and process developments.