Investigation of the physicochemical properties of CuO–CoO binary metal oxides supported on γ-Al2O3 and their activity for NO removal by CO

The dispersion and physicochemical behaviors of CuO–CoO binary metal oxides supported on γ-Al2O3 were characterized by XRD, LRS, XPS, H2-TPR, and in situ FT-IR techniques. Their activities were evaluated by NO–CO model reaction. The results indicated that (a) for lower loadings, CuO and CoO were able to be highly dispersed on the surface of γ-Al2O3 support; (b) the interaction between dispersed CuO and CoO upon γ-Al2O3 was discussed in the view of incorporation model. According to this model and obtained results, the surface dispersed Cu–O–Co species were considered to exist on the surface of γ-Al2O3; (c) CO or/and NO adsorption FT-IR results evidenced that the surface dispersed copper species could be reduced to lower valence by CO and the NO adsorption species converted with the increase in the temperature; (d) the surface dispersed Cu–O–Co species could be reduced to active Cu-□-Co species by CO among the mixture atmosphere. The formation of the surface synergetic oxygen vacancy (SSOV) was a crucial factor in the process of the NO–CO reaction. And a possible reaction pathway was tentatively proposed to discuss the NO–CO reaction based on all of these results.

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► Both CuO and CoO species were highly dispersed on γ-Al2O3 support at lower loadings.
► Surface dispersed Cu–O–Co species was considered to exist in CuO–CoO/γ-Al2O3 catalysts.
► The reduced Cu–O–Co (Cu-□-Co species) was presumed to be the active species.
► Surface synergetic oxygen vacancy (SSOV) played an important role in NO–CO reaction.