Low-temperature NOx capture and reduction via NO oxidation by O3 on Cu-CHA
Low-temperature NOx capture and reduction via NO oxidation by O3 on Cu-CHA
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DOI：
10.1016/j.apcata.2023.119099
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发表时间：
2023-02
期刊：
影响因子：
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通讯作者：
Yucheng Qian;Shunsaku Yasumura;Shinya Mine;Takashi Toyao;K. Shimizu
中科院分区：
文献类型：
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作者：
Yucheng Qian;Shunsaku Yasumura;Shinya Mine;Takashi Toyao;K. Shimizu
研究了Cu交换CHA分子筛（Cu-CHA）上NH3对NOx的瞬态还原，以及O3对NO的无催化氧化。在室温下，O3/NO比较低时，NO被O3氧化生成NO2，O3/NO比较高时，主要产物为N2 O 5。DFT计算证实了NO2+ O3生成N2 O 5的反应具有较低的活化能。瞬态红外测量表明，Cu-CHA在100 °C下暴露于NO + O3导致NOx以NO3−的形式存储在Cu 2+位点上。储存的NOx与NH3反应生成N2和NH 4 NO3。Cu-CHA上预吸附的NH_3被O_3氧化生成N_2和N_2O。预吸附的NH3与NO+ O3的反应导致N2的选择性生成。所获得的结果可能有助于开发一种新的O3辅助非稳态贫脱硝工艺，该工艺涉及捕获的NOx与NH3的反应或用储存的NH3还原NOx。
We studied the transient reduction of NOx with NH3over Cu-exchanged CHA zeolite (Cu-CHA) assisted by the catalyst-free oxidation of NO by O3. The room-temperature catalyst-free oxidation of NO by O3yielded NO2at low O3/NO ratio and N2O5as the main product at higher ratios. DFT calculations verified the reaction of NO2+ O3to N2O5proceeding with low activation energies. TransientoperandoIR measurements demonstrated that Cu-CHA exposure to NO + O3at 100 °C resulted in the storage of NOx as NO3−on the Cu2+site. The stored NOx reacted with NH3to yield N2and NH4NO3. Preadsorbed NH3on Cu-CHA was oxidized by O3to yield N2and N2O. The reaction of preadsorbed NH3with NO+O3caused the selective formation of N2. The obtained results may aid in developing a new O3-assisted unsteady-state lean De-NOx process involving reactions of captured NOx with NH3or reduction of NOx with stored NH3.