Cu-Ni/V2O5-SiO2 catalyst for the direct synthesis of dimethyl carbonate from carbon dioxide and methanol

The surface complex support of V2O5-SiO2(VSiO) was prepared by the method of surface reaction modification. VSiO supported Cu-Ni bimetallic catalysts were made using isovolumic impregnation. Adsorption and reaction of CO2 and CH3OH on catalyst were characterized by IR, TPD, TPSR and micro-reactor techniques. The results show that three active sites exist on Cu-Ni/VSiO catalyst: metal site(Cu-Ni alloy, denoted M), Lewis acid site(Vn+) and Lewis basic site(V = O); horizontally adsorped CO2, formed by shearingly adsorbed CO2 on M in cooperation with the adjacent Vn+, can dissociate into M -CO and V = O at about 138 degrees C and methanol dissociated into V - OCH3 and V - OH cooperated with Vn+ and adjacent V = O; the mainly reaction products of the reaction of CO2 and CH3OH on Cu-Ni/VSiO catalyst are DMC (with selectivity over 85%), CH2O, CO and H2O.