Effect of K₂O on Properties of Cu-Ni/V₂O₅-SiO₂ Catalyst for the Synthesis of Dimethyl Carbonate

V₂O₅-SiO₂(VSiO) supported Cu-Ni-K₂O catalysts for the synthesis of dimethyl carbonate were prepared using isovolumic impregnation. Based on TPR, TPD, IR and micro-reactor techniques, the effect of K₂O on the adsorption and reaction of CO₂ and CH₃OH on the catalyst were characterized. The results show that addition of K₂O exerts obvious influence on the charge distribution of the active sites on Cu-Ni/VSiO catalyst, increases the intensities of CO₂ horizontal adsorption state, while that of the dissociation state of methanol descends. When the ratio of K is above 15 %, K₂CO₃ is formed on the catalyst. Moreover, the main reaction products of CO₂ and CH₃OH on Cu-Ni-K₂O/VSiO catalyst are still DMC, H₂O, CO and CH₂O, and with the addition of K₂O, the conversion of reactants rise, but the selectivity of by-products decreases.