Investigation of the physicochemical properties of CuO/Sm2O3/γ-Al2O3 catalysts and their activity for NO removal by CO

• Copper oxide can be dispersed upon the surface of Sm2O3/γ-Al2O3.
• The possible interaction between copper oxide and samarium oxide upon γ­-Al2O3 has been tentatively proposed.
• The interaction between copper oxide and samarium oxide upon γ-Al2O3 could deactivate the surface dispersed copper oxide.
• Free-like NO3− species are recognized as the intermediates of the NO–CO reaction.

XRD, LRS, H2-TPR, and in situ FT-IR techniques were employed to investigate the dispersion, physicochemical behaviors of the Sm2O3 modification for CuO/γ-Al2O3 catalysts. And the catalytic performance for CuO/Sm2O3/γ-Al2O3 catalysts was tested by NO–CO reaction. The results indicated that (1) samarium oxide could be dispersed on the surface of γ-Al2O3 with a dispersion capacity of about 0.625 mmol/100 m2 and the supported copper oxide could be also dispersed upon the surface of Sm2O3/γ-Al2O3; (2) the reducibility of copper oxide was inhibited by the presence of samarium oxide, which could be influenced by the loading amounts of Sm2O3 upon γ-Al2O3 surface; (3) FT-IR results implied that the presence of samarium oxide species made the copper oxide hard to be reduced by CO while enhanced the NO strongly adsorbed; (4) NO–CO reaction could start to react only when both of them were in adsorbed states and the formation of free-like NO3− species was recognized as the intermediates of the reaction; (5) the reaction activity was negatively influenced by the introduction of samarium oxide in CuO/γ-Al2O3 catalysts. And a possible reaction pathway was tentatively proposed to discuss the NO–CO reaction based on all of these results.

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