Carbon dioxide hydrogenation over supported Au nanoparticles: effect of the support

Summarization: The present work aims to explore the impact of the support (MxOy: Al2O3, TiO2, Fe2O3, CeO2, ZnO) on the CO2 hydrogenation activity of supported gold nanoparticles (Au/MxOy) at atmospheric pressure. The textural, redox and surface properties of Au/MxOy catalysts were evaluated by various characterisation methods, namely N2 adsorption-desorption at -196 °C, temperature-programmed reduction in H2, high resolution transmission electron microscopy and X-ray photoelectron spectroscopy. The results revealed a strong influence of the support both on CO2 conversion and on products distribution. Gold nanoparticles supported on ZnO and CeO2 were highly selective towards methanol. TiO2- and Fe2O3-based samples demonstrated high CO2 conversion, leading, however, almost exclusively to CO and/or CH4. Au/Al2O3 was practically inactive in the investigated temperature range (200-350 °C). The following activity order, in terms of methanol formation rate, was obtained: Au/CeO2 > Au/ZnO > Au/Fe2O3 > Au/TiO2 > Au/Al2O3. Au/CeO2 exhibited a methanol formation rate of 4.1 × 10-6 mol s-1 gAu -1 at 250 °C, which is amongst the highest reported at ambient pressure, in spite of the chemical inertness of bare ceria. In view of the characterisation results, the superiority of the Au/CeO2 sample could be mainly ascribed to a synergistic effect linked to the Au-ceria interactions.Presented on: Journal of Co2 Utilizatio