Structure-activity correlation mechanism of additive-modified Cu-based catalysts for methanol synthesis <italic>via</italic> CO₂ hydrogenation

Aiming at the problems of insufficient activity and selectivity of Cu-based catalysts in CO2 hydrogenation to methanol, Al2O3, ZrO2 and CeO2 modified Cu-ZnO catalysts by the co-precipitation method were prepared, and the influence mechanism of additives on the structure-performance relationship of the catalysts was systematically explored. Through a variety of characterization methods such as XRD, N2 physical adsorption-desorption, TEM, H2-TPR, CO2-TPD and XPS, combined with catalytic performance evaluation experiments, the correlation between the microstructure of catalysts and the reaction performance of CO2 hydrogenation to methanol was analyzed in depth. The results show that metal additives significantly improve the performance of catalysts. After the introduction of additives, the specific surface area and pore volume of the catalysts increase, the grain size of Cu decreases, and its dispersion improves. The Ce-modified CZC catalyst exhibited the best performance, with the grain size of CuO as small as 11.41 nm, and the surface oxygen vacancy concentration (OⅡ/OⅠ = 3.15) was significantly higher than that of other samples. The reaction performance test shows that under the conditions of 2.8 MPa, 8000 h−1 and 280 °C, the CO2 conversion of the CZC catalyst reached 18.83%, the methanol selectivity was 68.40%, and the methanol yield was 12.88%, all of which are superior to other catalysts. Its excellent performance can be attributed to the fact that CeO2 enhances the metal-support interaction, increases the surface basicity, promotes the adsorption and activation of CO2, and simultaneously inhibits the reverse water-gas shift side reaction. This study clarifies the structure-activity regulation mechanism of additive modification on Cu-ZnO catalysts, providing a theoretical basis and technical reference for the development of efficient catalysts for CO2 hydrogenation to methanol.