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Identifying the catalyst chemical state and adsorbed species during methanol conversion on copper using ambient pressure X-ray spectroscopies

DOI: 10.1039/D0CP00347F DOI Help

Authors: Baran Eren (Weizmann Institute of Science) , Christopher G. Sole (University of Manchester) , Jesús Sánchez Lacasa (Weizmann Institute of Science) , David Grinter (Diamond Light Source) , Federica Venturini (Diamond Light Source) , Georg Held (Diamond Light Source) , Santiago Esconjauregui (Kingston University London) , Robert S. Weatherup (University of Manchester; Diamond Light Source; University of Oxford)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physical Chemistry Chemical Physics

State: Published (Approved)
Published: March 2020
Diamond Proposal Number(s): 19299

Abstract: Methanol is a promising chemical for the safe and efficient storage of hydrogen, where methanol conversion reactions can generate a hydrogen-containing gas mixture. Understanding the chemical state of the catalyst over which these reactions occur and the interplay with the adsorbed species present is key to the design of improved catalysts and process conditions. Here we study polycrystalline Cu foils using ambient pressure X-ray spectroscopies to reveal the Cu oxidation state and identify the adsorbed species during partial oxidation (CH3OH + O2), steam reforming (CH3OH + H2O), and autothermal reforming (CH3OH + O2 + H2O) of methanol at 200 °C surface temperature and in the mbar pressure range. We find that the Cu surface remains highly metallic throughout partial oxidation and steam reforming reactions, even for oxygen-rich conditions. However, for autothermal reforming the Cu surface shows significant oxidation towards Cu2O. We rationalise this behaviour on the basis of the shift in equilibrium of the CH3OH* + O* ⇌ CH3O* + OH* caused by the addition of H2O.

Subject Areas: Chemistry

Instruments: B07-C-Versatile Soft X-ray beamline: Ambient Pressure XPS and NEXAFS