Selective Vapor-Phase Hydrogenation of Furfural to Furfuryl Alcohol over Cu/Silica Catalysts

Vapor-phase hydrogenation of furfural (FAL) to furfuryl alcohol (FOL) was performed over 20 wt.% Cu supported on SiO2 under H-2 pressure. The Cu/SiO2 catalyst with a pore size of 6nm or larger provided FOL selectivity higher than 99% even at a high FAL conversion, whereas hydrogenolysis of FOL to 2-methylfuran (MF) proceeded over the Cu/SiO2 catalyst with small mesopores of 3 nm even at low FAL conversion. The selective transformation of FAL to FOL was regulated by the reaction temperature, H2 pressure, and contact time: the high FOL selectivity was achieved by minimizing the stepwise hydrogenolysis of FOL to MF, which is favorable under severe conditions. Under the optimum conditions, the FOL productivity was 3.1 kg(FOL) kg(cat)(-1)1 h(-1) with a FOL selectivity above 99% at 150 degrees C and an H-2 pressure of 2.0 MPa. Furthermore, the Cu/SiO2 catalyst could maintain the high activity on stream for 5h, with no significant catalyst deactivation.