Research On Modification And Characterization On Capacity Of CeO₂-ZrO₂ Complex Oxides

Aimed at CeO2-ZrO2 in automobile used by three-way catalysts, capacity of modifying CeO2-ZrO2 complex oxides was investigated in this thesis by doping different transition metals and alkali metals, choosing different precipitators and adopting co-precipitation method. The purpose is to obtain catalytic promoter which have high surface area, favorable reductive capacity at low temperature and high oxygen storage capacity.Firstly, the influence was investigated on capacity of CeO2-ZrO2 complex oxides by different precipitators. The result showed that samples prepared by (NH4)2CO3 can easily formed solid solution, and solid solution have high surface area, favorable reductive capacity at low temperature and high oxygen storage capacity.An orthogonal experiment was devised, and the influence was studied on capacity of CeO2-ZrO2 complex oxides by different loading content of transition metals (Fe, Mn and Cu), reaction time, pH value and the gross of surfactant. The result showed that samples doped simultaneously by Fe, Mn or Fe, Cu demonstrated high reactive property at low temperature. The best technical condition to gain the highest surface area was loading 4% Fe2O3, 9%MnO2, 3%CuO, and pH value was adjusted to 11 at the end of reaction, and the quantity of surfactant was 5% to the gross of sample, and reaction time was 30 minutes.The influence on capacity of CeO2-ZrO2 doped by alkali metals was also investigated. The result showed that samples could form more pores and surface area was increased after doped by 1%~3% BaO or CaO which could accelerate the course of catalytic reaction.Samples precipitated by rare earth complex oxides and alumina have high surface area, in which the redox capacity of samples precipitated by 60% alumina and 40% cerium was best.The output of samples was 10 times, and amplificatory experiment was processed after analyzing the result of all above experimental condition. The result showed that samples of amplificatory experiment could also form solid solution. The catalysts prepared by the samples have a good effect on treating various deleterious matters. The light-off temperature of CO is the lowest, and the value is 245.9 ℃. The light-off temperature of HC and NOx is 252.4 ℃ and 253.1℃. The conversion of CO, HC and NOx exceeds 80% when the temperature is up to 280 ℃, and the conversion of CO almost reaches 100% at 300℃.