CO 2 hydrogenation to methanol over CuO–ZnO–TiO2–ZrO2: a comparison of catalysts prepared by sol–gel, solid-state reaction and solution-combustion

Three CuO–ZnO–TiO2–ZrO2 catalysts with the same composition were prepared through sol–gel, solid-state reaction, and solution-combustion methods and characterized by X-ray diffraction (XRD), N2 adsorption, X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction with H2 (H2-TPR), reactive N2O adsorption, and adsorption of H2 and CO2 followed by temperature-programmed desorption (H2-TPD, CO2-TPD) techniques. Their catalytic performances for CO2 hydrogenation to methanol were tested in a fixed-bed reactor under the conditions of 200–280 °C, 3 MPa, and SV = 2400 mL gcat−1 h−1. The results indicated that the texture, structure, reducibility, and adsorption capacity for reactants of the CuO–ZnO–TiO2–ZrO2 catalyst were affected noticeably by preparation methods and the catalyst prepared by sol–gel method exhibited the highest CO2 conversion and methanol selectivity, which reached to 17.0% and 44.0%, respectively. The highest activity of the CuO–ZnO–TiO2–ZrO2 catalyst prepared by sol–gel method was attributed to the largest metallic Cu surface area and adsorption capacity for H2.