Gas phase hydrogenation of maleic anhydride to γ-butyrolactone by Cu–Zn–Ti catalysts

Abstract

Cu–Zn–Ti catalysts were prepared by coprecipitation method. The calcined and reduced Cu–Zn–Ti catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR), and N 2 adsorption. The calcined Cu–Zn–Ti catalysts were composed of CuO, ZnO, and amorphous TiO 2. There were two kinds of CuO species present in the calcined Cu–Zn–Ti catalyst. At a lower copper content, CuO species interacted with ZnO and TiO 2; at a higher copper content, both the surface-anchored and bulk CuO species were present. After reduction, metallic copper (Cu o) appeared in all Cu–Zn–Ti catalysts. Cu o produced by reduction of the surface-anchored CuO favored the deep hydrogenation of maleic anhydride. ZnO and TiO 2 had synergistic effect on the catalytic activity of Cu–Zn–Ti catalysts in hydrogenation of maleic anhydride.