Cu-Doped CoZn@NC promotes catalytic activity of furfural hydrogenation at low temperature: Regulation of copper

Abstract

The low-cost Cu-based catalysts have excellent selectivity in biomass hydrogenation, but it is challenging to improve their catalytic activity at low temperature. Herein, the trimetallic CuxCoZn@NC (where x = 0.1, 0.3, 0.5 mmol is the molar mass of Cu) were prepared by in suit pyrolysis using trimesic acid with stronger coordination ability. When it was applied to the furfural (FF) selective hydrogenation process, the catalytic yield of the optimal Cu0.3CoZn@NC reached >99 % under mild condition of 90 °C, which was 29 times superior to that of the CoZn@NC without Cu doping. The results demonstrate that the doping of Cu reduces the activation energy of CuxCoZn@NC and increases the catalytic activity at low temperature relative to CoZn@NC. The characterizations and density functional theory (DFT) calculations show that the incorporation of suitable Cu content enhances the interaction between Cu and Co. The amount of surface-active Co0 and the electron density are significantly enhanced, which effectively stimulates the dissociation of hydrogen. Moreover, the Lewis acid content is significantly increased to facilitate the adsorption and activation of FF. Meanwhile, the impact of Cu content variation on the performance of the multi-metal catalyst is discussed. This work is promising to establish a foundation for the accurate design of polymetallic catalysts through adjusting the Cu content to regulate the reaction activity and selectivity.