Synergetic effect of Pd and Ag dispersed on Al2O3 in the selective hydrogenation of acetylene

An alloy of palladium and silver dispersed on Al2O3 has been used for the selective hydrogenation of acetylene. The activity of Pd-Ag catalyst is lower than that of pure metal Pd catalyst. But the selectivity of Pd-Ag catalyst is higher and less impaired by temperature increase than that of Pd catalyst. X-ray diffraction (XRD) indicates that metal Pd and Ag can form an alloy on the surface of alumina. X-ray photoelectron spectroscopy (XPS) shows that the Pd-Ag alloy is formed with enrichment of Ag on the surface. Results of hydrogen adsorption isotherm, temperature-programmed reduction (TPR) and temperature-programmed desorption (TPD) reveal that the bulk of palladium of Pd-Ag catalyst adsorbed a small amount of hydrogen, which is desorbed at a higher temperature than that in the case of Pd catalyst. (C) 2000 Elsevier Science B.V. All rights reserved.