Focus on the modified CexZr1−xO2 with the rigid benzene-muti-carboxylate ligands and its catalysis in oxidation of NO

• It is a new idea to investigate NO oxidation over Cr/Ce0.2Zr0.8O2, which is modified with the rigid benzene-muti-carboxylate ligands.
• Cr/Ce0.2Zr0.8O2 is synthesized by one-pot method, which not only simplifies the preparation process, but also increases the surface area.
• In-situ FTIR indicates that adsorbed NO interacts with adsorbed O2 to generate NO2.
• Combined in-situ FTIR with XPS, it is found that the adsorption and activation O2 was the key factor.
• The one-pot method synthesized catalyst prepared with cinnamic acid as precipitant showed well ability to resist the poison effect of H2O and SO2.

A modified Cr/CexZr1−xO2 with the rigid benzene-muti-carboxylate ligands are prepared and studied on the oxidation of NO. 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, Ultra violet–visible diffuse reflectance spectroscopy (UV–vis DRS), X-ray photoelectron spectroscopy (XPS), NO(O2) Temperature-programmed desorption (NO(O2)-TPD) and in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The results demonstrated that the catalysts prepared with cinnamic acid as precipitant showed a higher surface area, a lower band gap and a stronger ability to adsorb reactant gas. Otherwise, the ligands such as terephthalic acid and trimesic acid were unfavorable for the synthesis of CexZr1−xO2 due to the long distance between the carboxyl groups. Furthermore, the π–π conjugated effect of the cinnamic acid balanced the charge in the precursor of the catalysts prepared with cinnamic acid, thus leading to their band gaps lower than that of other catalysts after calcinations. The catalytic performance over the catalysts prepared with cinnamic acid exhibited the highest NO conversion, and the preparation with one-pot method was simpler. Moreover, the catalyst prepared with one-pot method showed well ability to resist the poison effect of H2O and SO2, which was due to the large surface area. Finally, while combined the XPS analysis, in-situ DRIFTS demonstrated that the adsorbed NO interacted with the adsorbed O2 to generate NO2, and the adsorption and activation O2 was the key factor.

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