Reversible deactivation of a Au/Ce0.62Zr0.38O2 catalyst in CO oxidation: A systematic study of CO2-triggered carbonate inhibition

• Reversible deactivation on gold-supported catalysts.
• Oxidation of adsorbed CO on gold is retarded by the presence of CO2.
• Some adsorbed CO2 species – carbonates – inhibits the CO oxidation.
• CO2 adsorbs on the oxygen sites able to oxidize Au–CO at the metal–support interface.

Highly active supported gold catalysts frequently undergo substantial decrease in activity due to deactivation. The aim of this paper is to investigate a reversible inhibition phenomenon of the CO oxidation in an Au/Ce0.62Zr0.38O2 (Au/CZ) catalyst. The results of a systematic study of CO oxidation conditions (CO, O2, and CO2) are discussed. By identifying CO2 as an Au/CZ poison using isotopic transient analysis (13CO/12CO2), we also investigate the origin of inhibition activity by transient and modulated infrared spectroscopy in DRIFT mode. Results demonstrate that carbonate species are formed by reaction of CO2 with reactive lattice oxygen at the metal–support interphase, which in turn inhibits the replenishment of the vacancies by molecular oxygen. A microkinetic model that accounts for the reaction mechanism and inhibition by CO2 is proposed.

Figure optionsDownload high-quality image (298 K)Download as PowerPoint slide