Investigating the dynamic structural changes on Cu/CeO2 catalysts observed during CO2 hydrogenation

Abstract

CO2 hydrogenation is one route for partial CO2 abatement while producing valuable chemical products. Cu/CeO2 catalysts have attracted great interest as materials that facilitate the efficient hydrogenation of CO2 into methanol and CO. This paper investigates the effect of preparation methods on the structure, function and activity of Cu/CeO2 catalysts. The catalysts have been prepared by deposition–precipitation (DP) and the co-precipitation (CP) methods. The activity tests for the catalysts were conducted in a high-pressure packed bed reactor in the temperature range of 200–300 °C at 50 bar pressure. The DP catalyst showed higher methanol productivity and lower methanol selectivity compared its CP counterpart. The reasons for the higher performance of the DP catalyst and other structural and functional differences have been investigated through in-depth characterization using synchrotron radiated in-situ powder diffraction, DRIFTS, XPS, HR-TEM, TPR and N2O decomposition used to determine copper surface area. The higher methanol productivity in the DP catalyst was attributed to the higher Cu surface area and dispersion. Additionally, the in-situ synchrotron-based powder diffraction measurements provide fundamental insights on the interesting differences in the CeO2 structure i.e. the lattice parameter and the lattice microstrain during the reduction step that could be attributed to the size difference in the CeO2 support nanoparticles.