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

Abstract

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⁺ (Cu_O²⁺) and ZnO plays an important role in promoting the dispersion of Cu_O²⁺ 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⁺ (Cu_T²⁺) species are converted to a low binding energy Cu_O²⁺ on different levels. When ZnO is completely dispersed in the CuO crystalline lattice, the amount of Cu_T²⁺ 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.