High-performance Cu-ZnO@SiO2 Nano-catalyst for CO2 Hydrogenation to Methanol

Cu-based catalysts are widely employed for CO(2 )hydrogenation to methanol. However, their catalytic performance highly depends on supports. Herein, the nanospherical SiO2 support was synthesized by the Stober method and used as a component in Cu-ZnO@SiO2 catalyst. The catalyst was tested in hydrogenation of C-O2 to methanol and compared with the Cu-ZnO catalyst(6.9% yield of methanol and 36.5% selectivity of methanol) prepared via conventional coprecipitation process. It was found that Cu-ZnO@SiO2 catalyst exhibits the best catalytic performance, the yield of methanol reached 11.1% with 88.2% selectivity of methanol at n(H-2)/n(CO2)=3,230 degree celsius, 2.0 MPa and gaseous hourly space velocity(GHSV)=3600 mL center dot g(cat)(-1)center dot h(-1). The catalysts were thoroughly characterized by X-ray diffraction(XRD), scanning electron microscope(SEM), X-ray photoelectron spectroscopy(XPS), temperature-programmed reduction(H-2-TPR) and CO2 temperature-programmed desorption(CO2-TPD). The results show that Cu-ZnO@SiO2 catalyst has higher Cu dispersion and CO2 adsorption capacity, and the addition of SiO2 increases the Cu+/Cu(0 )molar ratio on the catalyst surface, which affects the catalytic performance. The characterization analysis of Diffuse reflectance fourier transform infrared spectroscopy(DRIFT) showed that CO2 generated methanol on Cu-ZnO@SiO2 catalyst mainly through reverse water gas reaction(RWGS)+CO hydrogenation path.