Effect of Au in Cs2.5H1.5PVMo11O40 and Cs2.5H1.5PVMo11O40/Au/TiO2 catalysts in the gas phase oxidation of propylene

The catalytic study of the gas phase oxidation of propylene has been carried out using heteropolyacids modified with gold. In addition, TiO2 was used as the main support for heteropolyacids and gold. Propylene oxidation was performed under different reaction conditions and in all the cases water was introduced owing to the beneficial effect in the formation of oxygenated products. It was found that deposition methods of Au onto heteropolyacid and heat pre-treatment procedure significantly affected the activity and the distribution of the products: sol immobilization promoted the total oxidation, whereas impregnation method the selective oxidation mainly to acrolein and acetic acid, depending on other reaction conditions. Depositing Cs2.5H1.5PVMo11O40 salt onto a preformed 1.5%Au/TiO2 a significant increase towards the formation of oxygenated products was observed at the expense of total combustion. In particular, acrolein was produced in a synergistic manner. FT-IR, XRD, XPS and TPR techniques were used for catalyst characterization. (C) 2007 Elsevier B.V. All rights reserved.