Optimization of N2O decomposition activity of CuO–CeO2 mixed oxides by means of synthesis procedure and alkali (Cs) promotion

Abstract

The fine-tuning of local surface chemistry of CuO–CeO₂ mixed oxides by means of synthesis procedure and alkali promotion towards the rational design of highly active catalysts is investigated. In particular, the impact of alkali (Cs) promotion on the N₂O decomposition activity (deN₂O process) of CuO–ceria mixed oxides, pre-optimized through the preparation procedure (co-precipitation among different synthesis routes), is explored. It was found that the co-optimization of the synthesis procedure (co-precipitation) and alkali loading (1.0 at Cs per nm²) can boost the decomposition of N₂O and resistance to O₂ inhibition, offering a half-conversion temperature (T₅₀) ca. 200 °C lower, when compared to a reference CuO–CeO₂ sample. A complementary characterization study involving surface area determination (BET method), pore size distribution (BJH method), X-ray diffraction (XRD), H₂ temperature-programmed reduction (H₂-TPR) and X-ray photoelectron spectroscopy (XPS) was undertaken to gain insight into structure–property relationships. The results revealed that the superiority of Cs-doped samples can be mainly attributed to the electronic effect of the alkali promoter towards the stabilization of partially reduced Cu⁺/Ce³⁺ pairs, which play a key role in the deN₂O process following a redox-type mechanism.