Solvent effects during the synthesis of Cr/Ce0.2Zr0.8O2 catalysts and their activities in NO oxidation

• We prepared Cr/Ce0.2Zr0.8O2 in four solvents via the common but simple method.
• The structural properties of Cr/Ce0.2Zr0.8O2 are determined by that of Ce0.2Zr0.8O2.
• H2O impregnation benefits for the well dispersion of Cr species.
• The amount of surface Ce3+ and Cr6+ ratios are the key factors in NO oxidation.

The solvent effects during the synthesis of a NO oxidation catalyst, Cr/Ce0.2Zr0.8O2 were evaluated with four solvents of the precursor solution (H2O, ethanol, ethylene glycol and isopropanol). The physicochemical characteristics were investigated by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area analysis, high-resolution transmission electron microscope (HR-TEM), X-ray photoelectron spectroscopy (XPS) and NO(O2) temperature-programmed desorption (NO(O2)-TPD). The results indicate that the structural properties of Cr/Ce0.2Zr0.8O2 are determined by the Ce0.2Zr0.8O2 support, and the solvents have impact on the surface properties. The adoption of ethylene glycol in the preparation of Ce0.2Zr0.8O2 support leads to the reduce of particles sizes, the increase of surface area and the generation of surface Ce3+, which is due to the appropriate polarity and the slow drying condition. Moreover, the present of H2O in the impregnation process could increase the dispersion of Cr species. The activity test confirms that the surface Ce3+ and Cr6+ ratios are the key factors in NO oxidation.

Figure optionsDownload as PowerPoint slide