ZrO₂ nanoparticles, ZrO₂ (P) and ZrO₂ (H), with different tetragonal phase contents, were prepared. ZrO₂ (P) possessed higher tetragonal phase content than ZrO₂ (H). Ni/ZrO₂ catalysts (10% (w/w)), using ZrO₂ (P) and ZrO₂ (H) as supports, were prepared using an impregnation method, and were characterized using XRD, Raman, H₂-TPR, XPS, and H₂-TPD techniques. Their catalytic performance in maleic anhydride hydrogenation was tested. The Ni/ZrO₂ (P) catalyst exhibited stronger metal-support interactions than the Ni/ZrO₂ (H) catalyst because of its higher number of oxygen vacancies and the low-coordinated oxygen ions on its surface. Consequently, smaller Ni crystallites and a higher C=C hydrogenation activity for maleic anhydride to succinic anhydride were obtained over a Ni/ZrO₂ (P) catalyst. However, the C=O hydrogenation activity of Ni/ZrO₂ (P) catalyst was much lower than that of the Ni/ZrO₂ (H) catalyst. A 43.5% yield of γ-butyrolacetone was obtained over the Ni/ZrO₂ (H) catalyst at 210 °C and 5 MPa of H₂ pressure, while the yield of γ-butyrolactone was only 2.8% over the Ni/ZrO₂ (P) catalyst under the same reaction conditions. In situ FT-IR characterization demonstrated that the high C=O hydrogenation activity for the Ni/ZrO₂ (H) catalyst could be attributed to the surface synergy between active metallic nickel species and relatively electron-deficient oxygen vacancies.

A Cu-based nano-catalyst has been widely used in the ethynylation of formaldehyde; however, the effects of the presence of Cu on the reaction have not yet been reported. CuO/SiO₂ catalysts with different Cu species were prepared by impregnation (IM), deposition–precipitation (DP), and ammonia evaporation (AE). The structural evolution of the Cu species in different states of the ethynylation reaction and the structure–activity relationship between the existence state of the Cu species and the catalytic properties of the ethynylation reaction were studied. The results show that the Cu species in the CuO/SiO₂ (IM), prepared using the impregnation method, are in the form of bulk CuO, with large particles and no interactions with the support. The bulk CuO species are transformed into Cu⁺ with a low exposure surface at the beginning of the reaction, which is easily lost. Thus, this approach shows the lowest initial activity and poor cycle stability. A high dispersion of CuO and copper phyllosilicate exists in CuO/SiO₂ (DP). The former makes the catalyst have the best initial activity, while the latter slows release, maintaining the stability of the catalyst. There is mainly copper phyllosilicate in CuO/SiO₂ (AE), which is slowly transformed into a highly dispersed and stable Cu⁺ center in the in situ reaction. Although the initial activity of the catalyst is not optimal, it has the optimal service stability.