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

Cu-Zn-Ti catalysts were prepared by coprecipitation method. The calcined and reduced Cu-Zn-Ti catalysts were characterized by Xray 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 TiO2. 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 TiO2; at a higher copper content, both the surface-anchored and bulk CuO species were present. After reduction, metallic copper (Cu degrees) appeared in all Cu-Zn-Ti catalysts. Cu degrees produced by reduction of the surface-anchored CuO favored the deep hydrogenation of maleic anhydride. ZnO and TiO2 had synergistic effect on the catalytic activity of Cu-Zn-Ti catalysts in hydrogenation of maleic anhydride. (c) 2006 Elsevier B.V. All rights reserved.