Green synthesis of heterogeneous copper-alumina catalyst for selective hydrogenation of pure and biomass-derived 5-hydroxymethylfurfural to 2,5-bis(hydroxymethyl)furan

In this work novel copper-alumina catalysts were prepared through a solvent-free solid-state grinding method ― a low cost and green catalyst preparation method for selective hydrogenation of 5-hydroxymethylfurfural (5-HMF) into 2,5-bis(hydroxymethyl)furan (BHMF). Under the optimized reaction conditions (3 MPa H2, 130 °C, 1 h), >99 % 5-HMF conversion and 93 % BHMF yield were obtained by using a 20CA (20 mol%Cu-Al2O3) catalyst. The catalyst characterization results could reveal that the high catalytic activity and selectivity could be attributed to the presence of both metallic and electrophilic copper (Cu°/Cu2+) species and the uniformly distributed copper nanoparticles. Furthermore, an integrated catalytic process was demonstrated for the first time for direct conversion of mono, di, and polysaccharides into the corresponding BHMF, obtained overall BHMF yield in the range of 25 %–48 %.