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Binary Ce-Zr(CZ),Pr-Zr(PZ) and ternary Ce-Zr-Pr(CZP) mixed oxides were prepared by an ammonia-aided co-precipitation method,and were aged in a steam/air flow at 1050 °C.X-ray diffraction(XRD),Raman spectra,X-photon spectra(XPS) and CO temperature programmed reduction(TPR) were carried out to characterize the micro-structure and reducibility of catalysts.The oxygen storage capacity(OSC) was evaluated with CO serving as probe gas.The results showed that a pseudo cubic structure was formed for the Zr-rich ceria-zirconia mixed oxides with Pr doping.The insertion of Pr prevented the phase segregation of the mixed oxides during the hydrothermal ageing.The Pr doped samples showed better redox performances in comparison with CZ,and the sample doped with 5 wt.% Pr showed the most remarkably promoted dynamic oxygen storage capacity.This phenomenon was closely related to both the reducibility and oxygen mobility of the mixed oxides.The introduction of praseodymium into ceria-zirconia could accelerate the oxygen migration by increasing the amount of oxygen vacancies,although it was difficult for Pr3+ ions themselves to participate in the oxygen exchange process. 相似文献
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采用过电压波形识别的单相接地暂态过电压抑制方法 总被引：1，自引：1，他引：0
运行经验表明消弧线圈在中性点非有效接地的电网正常运行和故障时的参数整定、调节困难,常常难以兼顾两种工作状态,限制了消弧线圈的应用。而随着坚强智能电网的建设,为实现调节控制故障的发展需求,快速准确地对弧光接地过电压进行抑制显得非常必要。为此,提出了采用过电压波形识别,有选择性地投入消弧线圈对单相接地暂态过电压进行抑制的方法,并在考虑消弧线圈自身损耗电导和线路对地电导的基础上,推导了电网对地电容电流实时计算的方法,从而实时准确地调节消弧线圈参数。依据该方法,建立了某110 kV变电站的EMTP仿真模型,分析了线路参数和负载变化对消弧线圈参数调节的影响以及有选择性地投入消弧线圈时对暂态过电压的抑制效果。仿真结果表明该抑制方法对电网正常运行状态影响小,且发生单相接地故障时对暂态过电压有很好的抑制效果。 相似文献
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