Mild and selective transfer hydrogenation of biomass-derived furfural to furfuryl alcohol over Cu/ZnO/Al2O3 with methanediol as the hydrogen donor

Abstract

A new catalytic transfer hydrogenation (CTH) strategy was developed for the continuous conversion of furfural (FF) into furfuryl alcohol (FFA) with Cu/ZnO/Al₂O₃ (CZA) as the catalyst under mild conditions. Methanediol was used as the hydrogen donor without any hazardous gas emission. FF was converted into FFA with up to 99% selectivity at 108 °C and normal pressure under an N₂ atmosphere. The highly dispersive copper species (Cu⁰, Cu⁺) with few Lewis acidic sites and η¹(O)-type adsorption ensured high selectivity and mild conversion. Deuterium-labelling experiments revealed that, in the presence of formaldehyde, water is split into hydrogen species, which can reduce FF to form FFA. A reasonable reaction mechanism for the conversion of FF into FFA via transfer hydrogenation was proposed. Notably, this strategy offers a new route to splitting water to generate in situ “green hydrogen” for the hydrogenation of unsaturated organic compounds under mild conditions based on non-noble heterogeneous catalysts.