CrOx/Ce0.2Zr0.8O2 NO oxidation efficiency
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The influence of drying condition on the formation of Ce0.2Zr0.8O2 was investigated and the NO oxidation efficiency over them was evaluated. These catalysts were investigated in detail by means of X-ray diffraction (XRD), High resolution transmission electron microscope (HR-TEM), Brunauer–Emmett–Teller (BET) surface area analysis, X-ray photoelectron spectroscopy (XPS) and NO(O2) Temperature-programmed desorption (NO(O2)-TPD). The results demonstrated that the slow drying rate caused by the decrease of the temperature and the use of the vacuum benefited for more Zr doped into CeO2 lattice and hence generated more Ce3+ on the surface, thus benefitting for the adsorption amount of O2. TEM results display the special morphology of the catalysts, which prepared under the conditions of slow drying rate. Gas-cell in-situ STEM confirms that the slow drying rate and the nature of the solvent made the particles growing along the (1 1 1) facet and finally displayed the coralloid particles. The coralloid catalysts prepared at the low drying temperature in the vacuum oven exhibited the highest NO oxidation efficiency, which reached 50.54% at 350 °C.

Impact Statement

The drying conditions during synthesis of Ce0.2Zr0.8O2 was investigated and correlated to the NO oxidation efficiency. The authors used in situ TEM with additional techniques such as XRD and XPS, to evaluate the resulting material structure as a function of drying rate. They concluded that a slow drying rate and the nature of the solvent increases surface area, and increases the number of oxygen vacancies leading to better oxygen adsorption thus higher NO oxidation activity.