Selective oxidation of propylene by using supported silver/gold catalysts

Propylene oxide (PO) is an important industrial intermediate which has traditionally been produced by the epoxidation of propylene with hydroperoxide or epichlorohydrin. The direct vapor-phase epoxidation of propylene, in the presence of oxygen and hydrogen, is the more environmentally friendly process. The selectivity to PO over silver catalysts supported on alumina and gold supported on TiO2 were investigated. The reactions were carried out between 80 and 225℃ with different feed compositions and space velocities. The catalysts were characterized by BET and XRD measurements. In the sol-gel prepared Ag/Al2O3 catalysts, surface areas in the range of 300-500 m2/g were obtained. But Au/TiO2 prepared by deposition-precipitation catalysts had much lower surface areas in the range of 14-17 m2/g. The Ag/Al2O3 catalysts showed almost no selectivity to PO and produced only CO2 and H2O as major products. By using Au/TiO2 catalysts. High selectivity to PO was found.