Abstract
CuO-based catalysts are usually used for CO oxidation owing to their low cost and excellent catalytic activities. In this study, a series of metal oxide (La2O3, Fe2O3, PrO2, Sm2O3, and MnO2)-doped CuO-based catalysts with mesoporous Ce0.8Zr0.2O2 support were simply prepared by the incipient impregnation method and used directly as catalysts for CO catalytic oxidation. These mesoporous 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), and H2 temperature programmed reduction (H2-TPR). It was found that the CuO and the dopants were highly dispersed among the mesoporous framework via the incipient impregnation method, and the strong metal framework interaction had been formed. The effects of the types of the dopants and the loading amounts of the dopants on the low-temperature catalytic performances were carefully studied. It was concluded that doped transition metal oxides could regulate the oxygen mobility and reduction ability of catalysts, further improving the catalytic activity. It was also found that the high dispersion of rare earth metal oxides (PrO2, Sm2O3) was able to prevent the thermal sintering and aggregation of CuO-based catalysts during the process of calcination. In addition, their presence also evidently improved the reducibility and significantly reduced the particle size of the CuO active sites for CO oxidation. The results demonstrated that the 15CuO-3Fe2O3/M-Ce80Zr20 catalyst with 3 wt. % of Fe2O3 showed the best low-temperature catalytic activity toward CO oxidation. Overall, the present Fe2O3-doped CuO-based catalysts with mesoporous nanocrystalline Ce0.8Zr0.2O2 solid solution as support were considered a promising series of catalysts for low-temperature CO oxidation.
Highlights
CO emitted from industrial processes and automobile exhaust has been one of the most serious environmental issues for a long time, and is greatly harmful to human health and the living environment [1,2]
The surface compositions and chemical states of the elements of the catalysts were analyzed by X-ray photoelectron spectroscopy (XPS) and detailed information related to the surface elements was obtained
H2 temperature programmed reduction (H2 -TPR) experiments were performed on homemade fixed bed reactor and the consumption of H2 was recorded by a LC-D200 mass spectrometer (TILON, US) by using 200 mg catalyst under the mixture of 5 vol % H2 -95 vol % Ar stream (50 mL/min)
Summary
CO emitted from industrial processes and automobile exhaust has been one of the most serious environmental issues for a long time, and is greatly harmful to human health and the living environment [1,2]. The incorporated ZrO2 does not participate in the catalytic reaction, it can modify the structure and the site of CeO2 lattice by forming Ce-Zr solid solution This greatly improves the oxygen storage capacity (OSC), thermal stability, and the dispersion of mixed oxides [17,18]. Great efforts have been devoted to improving the low-temperature catalytic activity of CuO-based catalysts, especially by doping various catalytic promoters, including transition metal oxides (such as MnO2 , Fe2 O3 , etc.) [22,23,24] and rare earth metal oxides (such as Sm2 O3 , PrO2 , La2 O3 , etc.) [25,26,27,28]. The effects of the types of different metal oxides dopants and their loading amounts on mesoporous Ce0.8Zr0.2O2 solid solution support Various characterizations, such as XRD, N2 low-temperature activities toward.
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