Effect of dispersed ZnO in Cu–Zn composite oxides on catalytic activity of anisole acetylation

Cu–Zn composite oxide catalysts were prepared by a co-precipitation method and used in the anisole acetylation reaction. Through experimental study and characterization analysis, we have found that the activity of the catalysts derived from the Lewis acidity of the octahedrally coordinated Cu2+ (CuO2+) and ZnO plays an important role in promoting the dispersion of CuO2+ active sites, adjusting the surface structure and coordination of the catalysts. Due to the integration of ZnO and CuO with different degrees of dispersion, some of the tetrahedrally coordinated Cu2+ (CuT2+) species are converted to a low binding energy CuO2+ on different levels. When ZnO is completely dispersed in the CuO crystalline lattice, the amount of CuT2+ is at its lowest and catalyst activity is highest, with the conversion of anisole reaching 92.8% with a selectivity for p-methoxyacetophenone (p-MAP) of 97.0% under solvent-free conditions. More importantly, the catalyst can be reused three times without any treatment.