Study on Cu-Ni/ZrO₂-SiO₂ catalyst for direct synthesis of DMC from CO₂ and CH₃OH

The surface complex support ZrO₂-SiO₂(ZrSiO) was prepared by surface reaction modification, and Cu-Ni/ZrSiO bimetallic catalyst was prepared by isovolumic impregnation. Adsorption and reaction of CO₂ with CH₃OH on the catalyst were characterized by IR, TPD, TPSR and microreactor techniques. The results showed that there exist three kinds of active sites on the catalyst: metal site M, Lewis acid site Zrⁿ⁺ and Lewis basic site Zr-O^-; CO₂ horizontal adsorption state, formed from its shearing state on M with the cooperation of adjacent Zrⁿ⁺, can be dissociated into M-CO and Zr-O^- at about 142 °C and CH₃OH dissociated into Zr-OCH₃ and Zr-OH with the cooperaton of Zrⁿ⁺ and adjacent Zr-O^-; the main reaction products on the catalyst are dimethyl carbonate (DMC) with a selectivity of over 85%, and less amounts of CH₂O, CO and H₂O.