Facilely fabricating mesoporous nanocrystalline Ce–Zr solid solution supported CuO-based catalysts with advanced low-temperature activity toward CO oxidation
A series of mesoporous nanocrystalline Ce–Zr solid solutions with different Ce/Zr ratios were successfully synthesized by the evaporation-induced self-assembly strategy, and were employed as catalytic supports of CuO-based catalysts for CO oxidation. These supports and catalysts were systematically characterized by X-ray powder diffraction (XRD), N2 physisorption, transmission electron microscopy (TEM), energy-dispersed spectroscopy (EDS) mapping, X-ray photoelectron spectroscopy (XPS), H2 temperature programmed reduction (H2-TPR), CO2 temperature programmed desorption (CO2-TPD), etc. The catalytic performances toward CO oxidation had been carefully evaluated over these CuO-based catalysts. The effects of various influencing factors, such as the Ce/Zr ratio, mesostructure, redox properties of the support, CuO loading amount and calcination temperature, on the low-temperature catalytic activity had been carefully investigated. The results showed that the catalyst supported on the support with a Ce/Zr ratio of 80/20 exhibited the highest catalytic activity. It was also found that the Ce–Zr solid solution mesoporous catalysts exhibited much higher catalytic activity than the counterparts without evident mesostructure, demonstrating the advantages of the mesoporous catalysts by providing more accessible catalytically active sites. Besides, the mesoporous Ce–Zr solid solution-supported catalysts with excellent redox properties displayed much better catalytic performances than the commercial γ-Al2O3-supported catalyst. The kinetic study also indicated that the apparent activation energy of the CO oxidation process was greatly affected by the Ce/Zr ratio, mesostructure, and redox properties of the support. Overall, the present CuO-based catalysts with mesoporous nanocrystalline Ce–Zr solid solutions as supports were considered as a series of promising catalysts for CO oxidation.