二氧化碳和丙烯直接合成甲基丙烯酸CuPW/TiO2催化剂的研究

The CuPWTiO2 catalysts were prepared with tetrabutyl titanate hydrolysis by aqueous solutions of Cu salts of the 12-tungstophosphoric acid via sol-gel method. Chemical composition, thermal stability, chemisorption character and reaction behaviours have been studied by different techniques including X-ray diffraction, thermogravimetric analysis, infrared spectrum analysis, inductively coupled plasma atomic emission spectroscopy, temperature-programmed desorption, and microreactor. The experimental results showed that inorganic precursor polyoxotungstate was introduced on the surface of titanium dioxide and formed to the CuPW/TiO2 hybrid materials. Under temperature of 623 K, the catalyst still remains the original Keggin structure of TPA. The experimental results showed also that CO2 chemisorbs at bridging oxygen of Cu—O—W(Lewis base site) and Cu2+(Lewis acid site) to form bridged adsorption states, that propylene chemisorbs on the surface of catalyst to form molecular absorption states, and that the main reaction products of CO2 with propylene on the catalysts are MAA, with propylene conversion of 4.3% under the reaction temperature of 563 K and 1 MPa, MAA selectivity of 96%.