Recycling of CO2: Probing the Chemical State of the Ni(111) Surface during the Methanation Reaction with Ambient-Pressure X-Ray Photoelectron Spectroscopy.
Using ambient-pressure X-ray photoelectron spectroscopy (AP-XPS), we studied the adsorption and reactions of CO2and CO2+ H2on the Ni(111) surface to identify the surface chemical state and the nature of the adsorbed species during the methanation reaction. In 200 mTorr CO2, we found that NiO is formed from CO2dissociation into CO and atomic oxygen. Additionally, carbonate (CO32-) is present on the surface from further reaction of CO2with NiO. The addition of H2into the reaction environment leads to reduction of NiO and the disappearance of CO32-. At temperatures >160 °C, CO adsorbed on hollow sites, and atomic carbon and OH species are present on the surface. We conclude that the methanation reaction proceeds via dissociation of CO2, followed by reduction of CO to atomic carbon and its hydrogenation to methane.
Christian
C
Heine
Barbara A J
BA
Lechner
Hendrik
H
Bluhm
Department of Materials Science and Engineering, University of California , Berkeley, California 94720, United States.
Miquel
M
Salmeron