Catalytic reduction of NO by CO over Cu/CexZr1−xO2 prepared by flame synthesis
Catalytic reduction of NO by CO over Cu/CexZr1−xO2 prepared by flame synthesis
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DOI：
10.1016/j.jcat.2010.04.001
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发表时间：
2010-06
影响因子：
7.3
通讯作者：
Runduo Zhang;W. Y. Teoh;R. Amal;Biaohua Chen;S. Kaliaguine
中科院分区：
文献类型：
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作者：
Runduo Zhang;W. Y. Teoh;R. Amal;Biaohua Chen;S. Kaliaguine
采用火焰喷雾热分解法制备了4%Cu/CexZr 1 − xO 2（x=0，0.25，0.50，0.75，1）复合氧化物，并采用N2吸附、XRD、XPS、O2-TPD和H2-TPR等手段对其进行了表征。对所制备的催化剂进行了等摩尔CO还原NO的评价（各3000 ppm，空速50，000 h-1）。Zr 4+以固溶体形式与CeO 2的结合稳定了Cu+物种，这反过来又有利于NO向N2 O的初始还原化学吸附。Cu/Ce_（0.75）Zr_（0.25）O_2催化剂在150 °C时具有独特的低温活性，N_2产率可达40%。这可追溯到CO快速氧化的低温活化（如原位DRIFTS探测），与表面活性晶格氧位点的丰度及其高还原性有关。在250°C和更高温度下，所有含Zr催化剂即Cu/CexZr 1-xO 2（x<1.0）的N2产率>85%（在350°C下> 100%），在废气流中基本上没有检测到中间N2 O。在这种情况下，发生了有机氮机制。
Mixed oxides of 4% Cu/CexZr1−xO2(x=0, 0.25, 0.50, 0.75, 1) were synthesized by flame spray pyrolysis and characterized by N2adsorption, XRD, XPS, O2-TPD and H2-TPR. The as-prepared catalysts were assessed for the equimolar reduction of NO by CO (3000ppm each, space velocity 50,000h−1). Incorporation of Zr4+in the form of solid solution with CeO2stabilizes the Cu+species, which was in turn beneficial for the initial reductive chemisorption of NO to N2O. A peculiar low-temperature activity giving 40% N2yield was found with the composition of Cu/Ce0.75Zr0.25O2at 150 °C. This is traced to the low-temperature activation of rapid CO oxidation (as probed by in situ DRIFTS), related to the abundance of surface reactive lattice oxygen sites and their high reducibility. At 250°C and above, a N2yield of >85% (and ∼100% at 350°C) was obtained for all Zr-containing catalysts i.e. Cu/CexZr1−xO2(x<1.0), with essentially no intermediate N2O detected in the exhaust gas stream. An organonitrogen mechanism is occurring in this case.