Investigation of surface synergetic oxygen vacancy in CuO–CoO binary metal oxides supported on γ-Al2O3 for NO removal by CO

The influence of CO pretreatment on the properties of CuO–CoO/γ-Al2O3 catalysts was investigated by SEM, TEM, XRD, LRS, XPS, TPR, and in situ FT-IR techniques. And the activities were measured by NO removal by CO. It was shown that the CuO–CoO/γ-Al2O3 catalysts following CO pretreatment exhibited extremely high activity and selectivity. The interaction between copper oxide and cobalt oxide upon the γ-Al2O3 support before and after CO pretreatment was tentatively discussed in the view of incorporation model. According to this model, the dispersed Cu–O–Co species could be reduced to Cu-□-Co species by CO pretreatment, which was considered to be the primary active component for this reaction. FT-IR results suggested that CO was apt to adsorb on Cu+ sites rather than Co2+ while the NO adsorbates could convert to much more stable species with the temperature increasing. Undoubtedly, it was the surface synergetic oxygen vacancy coupled with the adjacent Cu and Co ions that guaranteed the reaction well processing over the CO pretreated samples. As a result, a possible mechanism was tentatively proposed.

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► CuO–CoO/γ-Al2O3 catalysts after CO pretreatment exhibited extremely high activity and selectivity.
► Surface synergetic oxygen vacancy could be obtained by CO pretreatment in CuO–CoO/γ-Al2O3 catalysts.
► Surface synergetic oxygen vacancy played a curial role in NO reduction by CO.