Effect of the metal-support interaction in the Cu/ZnO catalyst on its performance in the hydrogenation of furfural to furfuryl alcohol

A series of Cu/ZnO catalysts were prepared by the coprecipitation method and the effect of Cu/Zn ratio on the strong metal support interaction (SMSI) as well as its relation to the catalytic performance of Cu/ZnO in the gaseous hydrogenation of furfural to furfuryl alcohol was investigated. The H₂-TPR, XRD, SEM, TEM and XPS characterization results reveal that there exists the SMSI effect in the Cu/ZnO catalyst that influences the catalyst microstructure. ZnO support, acting as a geometric modifier on the active metal Cu particles, has a significant influence on the electronic state of the surface Cu species. The strength of SMSI is related to the Cu/Zn ratio and the SMSI strength of various Cu/ZnO catalysts follows the order of 20Cu/ZnO > 40Cu/ZnO > 60Cu/ZnO > 80Cu/ZnO. Under the same reaction conditions, the lifetime of the 20Cu/ZnO catalyst with a furfural conversion of above 80% is only 5 h, in comparison with the lifetime of 28 h for the 60Cu/ZnO catalyst. That is, appropriate SMSI can enhance the stability of the Cu/ZnO catalyst in the hydrogenation of furfural to furfuryl alcohol, whereas excessive SMSI is detrimental to the catalyst activity.