Effect of copper source on the structure–activity of CuAl2O4 spinel catalysts for CO hydrogenation

Due to the complexity of the structure–activity relationship of the CuAl2O4 spinel catalyst, optimization of the catalyst structure is a great challenge. In this paper, three different CuAl2O4 spinel catalysts were prepared by the solid-phase method using copper hydroxide, copper nitrate, and copper oxide as the copper source, respectively, to study the difference in the structure of CuAl2O4 spinel catalysts induced by the raw materials and the catalytic behavior for CO hydrogenation. The structure of CuAl2O4 spinel catalyst was characterized by XRD, BET, SEM, TEM, H2-TPR and XPS. The activity of CO hydrogenation over the CuAl2O4 spinel catalyst without pre-reduction was evaluated in the slurry reactor. The results demonstrated that different copper sources had obvious influence on the CuAl2O4 spinel texture properties, surface enrichment degree, as well as decomposition and reduction ability, which further regulated the ratio of Cu+/Cu0 and thus affected the catalytic performance, especially the alcohol distribution. The CuAl2O4 spinel, employing copper hydroxide as the copper source, showed better selectivity of C2+OH, which was assigned to a higher ratio of Cu+/Cu0, along with larger pore size and pore volume. Moreover, the synergistic effect between Cu0 and γ-Al2O3 improved the selectivity of dimethyl ether.