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NO
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reduction over Ir-based catalysts in the presence of excess oxygen with hydrocarbon as a reductant was investigated in the focus on observing microstructure of Ir particle supported on various carriers and structural evolution of highly active Ir-based catalysts in the NO
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reduction. Characterization of Ir-based catalysts using SEM, TEM, XRD, CO chemisorption and XPS, and reaction studies on various Ir-based catalysts have proved that the formation of relatively large Ir metal particle with 40–60 nm of nanocrystal size carried on inert supports has been a prerequisite for the evolution of high activities in the NO
x
reduction rather than the formation of Ir metal state on the catalyst. Furthermore, in inert gas conditions in a high temperature range of 850–950°C, Ir metal was easily formed by using the support such as TiO2 and ZrO2 that drastically decreased its specific surface area in the temperature range. 相似文献
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Catalytic lean NO reduction system in periodic two steps, lean/rich operations has been investigated over Rh-based catalysts. The investigation was done using a pulse reaction. In the reaction, after H2 or CO was pulse-injected for a moment to achieve reducing conditions, the highly dispersed Rh catalyst could catalyze NO reduction at 200–400 °C in lean conditions for 1 min. Furthermore, NO was effectively reduced over the highly dispersed Rh/β-zeolite after exposure to the gas composed of 3% of O2, 40 ppm of SO2 and balance of He at 300 and 400 °C for 24 h. 相似文献
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Dosimetric methods used for interventional and diagnostic radiology are reviewed and evaluated, including terms, quantities, equipment, calibration and measurements. Measurement of local skin dose and estimation of maximum local skin dose are emphasised. Aspects related to dosimetry in computed tomography and to methods of determining organ and tissue doses are not considered. 相似文献
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