Operando Observation of Hydrogenation of Carbon Dioxide by Near Ambient Pressure X-ray Photoelectron Spectroscopy

Résumé fourni par la source

Hydrogenation of carbon dioxide (CO2) on copper/zinc oxide-based catalysts was investigated using near-ambient pressure X-ray photoelectron spectroscopy (AP-XPS). An initial hydrogenation step of CO2 to formate was studied using Zn-deposited single-crystal Cu surfaces. CO2 activation on the model catalysts leads to the formation of carbonates (CO3) on the surface in the presence of near-ambient pressure CO2 and hydrogen (H2). The addition of a small amount of water to the feed gas enhances the hydrogenation of CO2 into formate. This indicates that hydroxyl produced through dissociative adsorption of water is a source for the CO2 hydrogenation observed under the present reaction conditions. We also performed operando spectroscopy of an industrial catalyst for methanol synthesis at higher pressure to reveal the chemical states of the catalyst and adsorbed intermediates during the catalytic reaction. In-situ formation of active catalytic sites was detected by operando hard X-ray photoelectron spectroscopy. Analysis of the reaction products in the presence of CO2 and H2 gases shows the formation of methanol and CO. The rate of methanol synthesis correlates with the dynamic changes in the chemical states of the catalyst, and the reaction intermediates adsorbed on the catalyst.

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