A comparison study on non-thermal plasma-assisted catalytic reduction of NO By C3H6 at low temperatures between Ag/Usy and Ag/Al2O3 catalysts
A comparison study on non-thermal plasma-assisted catalytic reduction of NO By C3H6 at low temperatures between Ag/Usy and Ag/Al2O3 catalysts
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DOI：
10.1016/j.cattod.2007.06.001
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发表时间：
2007-08
期刊：
影响因子：
5.3
通讯作者：
Junhua Li;R. Ke;W. Li;J. Hao
中科院分区：
文献类型：
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作者：
Junhua Li;R. Ke;W. Li;J. Hao
对低温等离子体(NTP)辅助的丙烯选择性催化还原(SCR)在Ag/USY和Ag/Al_2O_3催化剂上的性能进行了对比研究。在100°C-200°C时，Ag/USY在热SCR中几乎没有活性，而在NTP辅助下的SCR中，在100°C-200°C时表现出明显的催化活性。研究发现，在NTP的辅助下，HC-SCR中的关键中间体，如NCO、CN、含氧物和一些含N的有机物种得到了丰富。两种催化剂对上述中间体的反应性能没有明显差异。然而，一些证据表明，吸附的NOx物种的不同性质导致了在Ag/USY和Ag/Al_2O_3上SCR反应的不同。Ag/Al_2O_3的TPD图谱表明，催化剂上生成的硝酸盐在低温下相当稳定，可能占据了活性中心，不利于SCR反应。Ag/USY催化剂上的硝酸盐是不稳定的，其中单一的硝酸盐物种可能对低温SCR反应有贡献。
A comparison study was carried out on non-thermal plasma (NTP)-assisted selective catalytic reduction (SCR) of NOxby propene over Ag/USY and Ag/Al2O3catalysts. Ag/USY was almost inactive in thermal SCR while it showed obvious activities in NTP-assisted SCR at 100°C–200°C. Although the NOxconversion over Ag/Al2O3was also enhanced at 300°C–400°C by the assistance of NTP, it was ineffective below 250°C. The intermediates over Ag/USY and Ag/Al2O3were investigated using in situ DRIFTS method. It was found that key intermediates in HC-SCR, such as NCO, CN, oxygenates and some N-containing organic species were enriched after the assistance of NTP. The differences in the behaviors of above intermediates were not found between these two kinds of catalysts. However, some evidences suggested that different properties of the absorbed NOxspecies resulted in the distinction of SCR reactions over Ag/USY and Ag/Al2O3. TPD profiles of Ag/Al2O3showed that nitrates formed over the catalyst were quite stable at low temperatures, which might occupy the active sites and were unfavorable to SCR reactions. The nitrates over Ag/USY were unstable, among which the unidentate nitrate species is probably contributed to the SCR reactions at low temperatures.