Modified Cu–ZnO Catalysts Supported on the Mixture of ZnO and Zn–Al Oxide for Methanol Production via Hydrogenation of CO and CO₂ Gas Mixture

Cu-based catalysts were created using a two-step co-precipitation method, which can produce methanol from synthesis gases (H₂ and CO) that also contain CO₂. The catalysts were manufactured by a two-step co-precipitation method and compared with catalysts manufactured by a one-step co-precipitation method. The supports with Zn/Al = 1 (10ZA) and Zn/Al = 2 (20ZA) showed higher ZnAl₂O₄ ratios than the other catalysts, and the catalysts using these supports showed a similar trend to the ZnAl₂O₄ ratio. Cu–ZnO/mixture ZnO and ZnAl₂O₄ catalysts with more ZnAl₂O₄ (C10Z/20ZA and C20Z/10ZA) showed lower carbon and CO conversion losses and lower sintering of Cu (200) particles at the reaction temperatures (250, 300, and 350 °C) than the Cu–ZnO-ZnAl₂O₄ (C30ZA) catalyst. Cu–ZnO/mixture ZnO and ZnAl₂O₄ using support with Zn/Al = 2 (C10Z/20ZA) achieved dispersion of Cu (44.2%) and a methanol yield (409.0 g_MeOH/kg_cat./h) at a reaction temperature of 250 °C, GHSV of 4,444 h⁻¹, and 40 bar.