Conversion of CO2 to CO, which can be further upgraded using Fischer-Tropsch or methanol synthesis, represents a promising strategy for offsetting CO2 emissions using H2 generated by renewable energy.1 During thermocatalytic CO2 reduction by H2, low loading of Ni/CeO2 provides high selectivity to CO over CH4, while higher Ni loading improves CO2 hydrogenation activity but reduces CO selectivity. In situ XANES and AP-XPS reveal Ni to be metallic for all catalysts, suggesting that the selectivity trend is due to structural rather than oxidation state effects. Isotope studies using C18O2 with time-resolved in situ FTIR spectroscopy and pulsed mass spectrometry reveal that oxygen exchange with the CeO2 support occurs beyond the surface layer. The results suggest that H2 dissociation by metallic Ni promotes C-O bond breaking in CO2 adsorbed on reduced ceria and that oxygen vacancies are filled by oxygen from the adsorbed CO2.2 Bimetallic Ni-Fe catalysts improve the CO selectivity without significantly compromising activity, synergizing the high activity of Ni catalysts and the high CO selectivity of Fe. TPR results reveal bimetallic interactions between Ni and Fe, and XANES analysis shows that the majority of Fe in the bimetallic catalysts is oxidized.3 The trends in bimetallic modification and support effects should guide efforts to develop non-precious metal catalysts for the selective production of CO from CO2 hydrogenation.

Tuning CO2 hydrogenation pathways via Ni-ceria support interactions and Ni-Fe bimetallic formation

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.