Preparation Of Cerium Zirconium Solid Solution And Its Catalytic Performance For CO Oxidation

Although the ceria-zirconia solid solution with good thermal stability is widely applied to the field of three-way catalysts (TWCs), its catalytic activity needs further improving as regulatory requirements become stricter. The paper mainly studies different ceria-zirconia solid solutions synthesized by three methods to improve the catalytic activity of the solid solution. First, the inverse co-precipitation is used to prepare the solid solution doped with cheap meatals. Second, the Cu-doped solid solution is fabricated by a simple solvothermal strategy. Third, we use the impregnation method to synthesize the solid solution coated by CuO. Then we discuss the fabrication, component, property evaluation and catalytic mechanism of the pruducts.1. One-Pot synthesis of Cu-doped CeZrO2 solid solution for CO oxidationIn our work, CeZrO2 nanoparticles with 15 wt.% CuO dopant were fabricated by a template-free solvothermal method. We observed monodispersed nanospheres with average size of 130 nm by transmission electron microscopy (TEM) and the surfaces of these spheres were rough. It was confirmed that Cu species were introduced into the lattice of the solid solution by XRD. More oxygen vacancies were generated owing to the Cu dopant, which promoted the catalytic property. 2. Inverse co-precipitation synthesis of M-doped (M=Cu, Fe, Al) ceria-zirconia solid solutions for CO oxidationCeria-zirconia solid solutions with 15 wt.% MxOy dopant were synthesized through a inverse co-precipitation method. The powder X-ray diffraction (XRD) was used to characterize the structure of the samples. The results of XRD and Raman spectroscopy manifested that the dopants were well diffused into the lattice. Raman also implied that dopants could create more oxygen vacancies and the doping effect of Cu was most obvious. The largest reduction peak area and the lowest reduction temperature in the H2-TPR profiles indicated the excellent catalytic property of the Cu-doped sample. Furthermore, the as-obtained Cu-doped sample revealed the best catalytic performance in CO oxidation in accordance with the results of the Ramanand the H2-TPR. 3. Synthesis of CuO-supported CeO2-ZrO2 nanospheres:structural studies and CO catalytic oxidationThe Zr-doped CeO2-CuO catalyst was obtained by two steps:the ceria-zirconia solid solution synthesized through a inverse co-precipitation method was used as the support and then were calcined with Cu (NO3)3 solution to get Zr-doped CeO2-CuO. The XRD of the products displayed the typical peaks of CuO and CeO2. The TEM showed that the product coated by CuO dispersed well. The synergistic effect between CuO and CeZrO2 solid solution as well as the good dispersion improved the catalytic property of the solid solution.