Methanol Synthesis from CO2 Hydrogenation over CuO–ZnO–TiO2 Catalysts: The Influence of TiO2 Content

Abstract A series of CuO–ZnO–TiO 2 catalysts with various TiO 2 loadings were prepared by using a co‐precipitation method. The prepared catalysts were characterized by using X‐ray diffraction (XRD), N 2 adsorption, reactive N 2 O adsorption, X‐ray photoelectron spectroscopy (XPS), temperature‐programmed reduction (TPR), hydrogen temperature programmed desorption (H 2 ‐TPD), and CO 2 ‐TPD techniques, and tested the extent of methanol synthesis from carbon dioxide (CO 2 ) hydrogenation. The results indicate that the addition of TiO 2 to the CuO–ZnO catalyst makes the copper species exist in an amorphous‐like structure or in much smaller crystallites, which promotes the reduction of CuO. Upon increasing the TiO 2 loading, the metallic Cu surface area ( S Cu ) of the catalyst rises first and then decreases, exhibiting a maximum at a TiO 2 loading of 10 %. The results of the catalytic experiments reveal that the addition of TiO 2 favors the production of methanol, and an optimum catalytic activity is obtained at a TiO 2 loading of 10 %. Moreover, the methanol yield increases linearly with the S Cu of the catalysts, thereby indicating that the addition of TiO 2 enhances the S Cu but not the intrinsic activity.