Effect of preparation condition on performance of Ag-MoO3/ZrO2 catalyst for direct epoxidation of propylene by molecular oxygen

The Ag-MoO3/ZrO2, catalyst for an epoxidation of propylene by molecular oxygen was prepared by the precipitation/impregnation method, and characterized by N-2 adsorption at low temperature, XRD, NH3-TPD and CO2-TPD. The effects of preparation condition of ZrO2 support on its physicochemical properties and catalytic performance were studied. The results show that suitably low surface area, big pore size, and modest and weak surface acidity-basicity for the Ag-MoO3/ZrO2 catalyst are in favor of the selective formation of propylene oxide. High surface area, abundant micro-pore structure and strong acidity-basicity or acidity-free are liable to the deep oxidation of propylene to CO2 and H2O. As the support of the Ag-MoO3 catalyst for an epoxidation of propylene, the monoclinic phase of ZrO2 is preferable to tetragonal one. Suitably larger particles of Ag and highly dispersed MoO3 on the Ag-MoO3/ZrO2 catalyst are beneficial to improve the selectivity to propylene oxide. (c) 2005 Elsevier B.V. All rights reserved.