Regulation of sol-gel derived Cu-M/Al2O3 by metal additives for the selective catalytic transfer hydrogenation of furfural

Abstract

Furfural is an indispensable platform compound derived from biomass resource and can be hydrogenated to produce a series of high value-added chemicals. In order to overcome the disadvantages of low selectivity and poor stability during furfural hydrogenation, design of promising Cu catalysts with well-disentangled catalytic theory becomes a hot topic. In this work, a series of Cu-M/Al2O3 (M=Fe, Co, Ni, Ce) catalysts were prepared by sol-gel method to make a uniform ternary metal composition. Distinctive product distribution for the catalytic transfer hydrogenation of furfural was obtained depending on the specific Cu-M/Al2O3 system. Among them, the Cu-Fe/Al2O3 displayed superior selectivity of 2-methylfuran compared to any other catalysts. The introduced metal additive acted as the electron donor to regulate the surface dispersion of Cu species. Higher percentage of surface Cu0+Cu+ species were formed on Cu-Ce/Al2O3 and Cu-Fe/Al2O3, accounting for the much lower activation energy and better dissociation ability for isoproponal. If Cu-Ni/Al2O3 or Cu-Ce/Al2O3 was used as the catalyst, hydrogenation happened on the furan ring. Whilst Cu-Co/Al2O3 was more preferentially used to produce 2-pentanol and 2-pentanone, with large amount of copper species in oxidative states. The yield of 2-MF reached 84 % at 220 ºC in N2 at ordinary pressure by Cu-Fe/Al2O3 with the specific rate of 106.8 mmolFAL·gCu−1·h−1.