Hyper-cross-linked polymer based carbonaceous materials as efficient catalysts for ethyl levulinate production from carbohydrates

BACKGROUND Catalytic upgrading of biomass into various alkyl levulinates has gained wide attention recently. Particularly, ethyl levulinate (EL) shows great potential as gasoline additive and substitute of biodiesel fuels. RESULTS Hyper-cross-linked organic polymer based carbonaceous materials with large surface areas and strong Brϕnsted acidity were synthesized and developed as highly efficient solid acids for the direct transformation of biomass derived carbohydrates into biofuel candidate ethyl levulinate (EL). Controllable Brunauer–Emmett–Teller (BET) surface area and proper acid density of as-prepared carbonaceous materials were demonstrated to be crucial for the successful synthesis of EL. Among the catalysts, α,α′-dichloro- p -xylene derived hyper-cross-linked organic carbocatalyst (HDS-3.6) exhibited the best results for EL formation with the optimal yield of 70.3% at a temperature of 423 K, which was comparable with those of frequently-used solid acids such as commercial Amberlyst-15 and metal oxides. The presence of dimethyl sulfoxide (DMSO) in the catalytic system facilitated the production of intermediates 5-hydroxymethylfurfural (HMF) and 5-ethoxymethylfurfural. Notably, the hyper-cross-linked organic polymers with abundant Brϕnsted acid sites were much more effective in the catalytic synthesis of levulinate esters from ketoses. CONCLUSION The prepared hyper-cross-linked organic polymers were efficient and robust catalysts to produce various biomass derived alkyl levulinates with high activity and stability. © 2019 Society of Chemical Industry