Copper-ceria solid solution with improved catalytic activity for hydrogenation of CO₂ to CH₃OH

A copper-ceria solid solution and ceria-supported copper catalysts were prepared and used for the catalytic hydrogenation of CO₂ to CH₃OH. According to site-specific classification and quantitative analyses (X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, H₂ temperature-programmed reduction, and CO adsorption), the interfaces of the prepared catalysts were classified as Cu incorporated into ceria (Cu-O_v-Ce_x), dispersed CuO (D-CuO-CeO₂), and bulk CuO (B-CuO-CeO₂) over the CeO₂ surface. These results, together with those of activity tests, showed that the Cu-O_v-Ce_x species was closely related to the CO₂ hydrogenation activity and resulted in a much higher turnover frequency of CH₃OH production than that observed with the D-CuO-CeO₂ and B-CuO-CeO₂ species. Thus, the copper-ceria solid solution exhibited improved activity due to the higher Cu-O_v-Ce_x fraction.