High dispersion by Cd incorporation leads to accelerate methanol synthesis rate in CO2 hydrogenation over Cu-Zn/SiO2 catalysts

Green methanol fuel synthesis by CO₂ hydrogenation is regarded as one of the potential viable techniques for meeting future energy demands. Enhancing catalytic performance and process knowledge are crucial for the practicality of catalyzed CO₂ conversion pathways. Here, co-precipitation was utilized to prepare Cu-Zn bimetallic catalysts based on silica gel. To examine the stimulating function of Cd metal, the produced catalysts were doped with varying concentrations of the Cd metal. The nitrogen adsorption-desorption isotherm revealed mesoporous nature of catalysts. The X-ray diffraction (XRD) investigations as well as Field Emission Scanning Electron Microscopy (FESEM) studies concluded higher degree of metal oxides dispersion on surface of silica gel support. The study of Fourier-transform infrared (FTIR) spectroscopy revealed successful incorporation of metal oxides on surface of silica gel support by originating absorption band in metal oxides regions. The X-ray photoelectron spectroscopy (XPS) exposed surface chemical nature of the Cu-Zn/SiO₂ catalysts promoted by Cd metal. On the top of that, XPS investigations confirmed the results derived from XRD and FESEM investigations in terms of catalysts dispersion over silica gel support by Cd promotion. The methanol synthesis rate was accelerated from 167 to 197 g._meth/kg._cat.h by incorporating Cd to the parent Cu-Zn/SiO₂ catalyst. Furthermore, similar trend in terms of accelerating methanol synthesis rate was sustained with further addition of Cd content to Cd-promoted silica gel supported Cu-Zn catalysts. The activity data demonstrated active and selective profile of Cd for CO₂ reduction to methanol by taking into account methanol synthesis rate and selectivity. Structure-activity studied documented in promoting character of Cd metal as structural promoter in CO₂ hydrogenation to methanol.