Elucidating the structure, redox properties and active entities of high-temperature thermally aged CuO x –CeO 2 catalysts for CO-PROX

• Published in: Physical chemistry chemical physics : PCCP Vol. 23; no. 29; pp. 15582 - 15590
• Main Authors: Qiu, Zhihuan, Guo, Xiaolin, Mao, Jianxin, Zhou, Renxian
• Format: Journal Article
• Language: English
• Published: 28.07.2021
• ISSN: 1463-9076; 1463-9084
• DOI: 10.1039/D1CP01798E

CuO x –CeO 2 catalysts with different copper contents are synthesized via a coprecipitation method and thermally treated at 700 °C. Various characterization techniques including X-ray diffraction (XRD) Rietveld refinement, N 2 adsorption–desorption isotherms, X-ray photoelectron spectra (XPS), UV-Raman, high-resolution transmission electron microscopy (HRTEM), temperature-programmed reduction (TPR) and in situ diffuse reflectance infrared Fourier transform spectra (DRIFTs) were adopted to investigate the structure/texture properties, oxygen vacancies, Cu–Ce interaction and redox properties of the catalysts. After the thermal treatment, the catalysts exhibited outstanding catalytic properties for the preferential oxidation (PROX) of CO (with the T 50% of 62 °C and the widest operation temperature window of 85–140 °C), which provided a new strategy for the design of Cu–Ce based catalysts with high catalytic performance. The characterization results indicated that moderately elevating the copper content (below 5%) increases the amount of highly dispersed Cu species in the catalysts, including highly dispersed surface CuO x species and strongly bonded Cu–[O x ]–Ce species, strengthening the Cu–Ce interaction, increasing oxygen vacancies and promoting redox properties, but a further increase in copper content causes the agglomeration of crystalline CuO and decreases the highly dispersed Cu species. This work also provides evidence from the perspective that the catalytic performance of CuO x –CeO 2 catalysts for CO-PROX at low and high reaction temperatures is dependent on the redox properties of highly dispersed CuO x species and strongly bonded Cu–[O x ]–Ce species, respectively.