Solvothermal synthesis and characterization of ceria–zirconia mixed oxides for catalytic applications

摘要

Solvothermal synthesis under supercritical conditions (400 ℃) and high autogenous pressure (about 40 MPa), has been carried out for the direct preparation of nanocrystalline powders of CeO2, Ce0.85Zr0.15O2, Ce0.75Zr0.25O2, Ce0.65Zr0.35O2 and Ce0.5Zr0.5O2 which are characterized for applications as catalysts for oxygen storage in automotive catalysis. The synthesis was carried out in the presence of polyethylene glycol and water. For the characterization, x-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS) and the Brunauer–Emmet–Teller (BET) technique were employed. The oxygen storage capacity (OSC) of as-prepared and calcined samples without loading of noble metals was measured using thermogravimetric–differential thermal analysis (TG–DTA) at 600 ℃ with a continuous flow of CO–N2 gas and air alternately. Ce0.5Zr0.5O2 nanoparticles with a BET surface area of 102 m2 g-1 exhibited the highest OSC of 0.073 50 mol-O2/mol-CeO2. The OSC values obtained increased with increasing the amount of ZrO2 doping in the samples.