Spectroscopic Evidence of Efficient Generation of Dicopper Intermediate in Selective Catalytic Reduction of NO over Cu-Ion-Exchanged Zeolites
Spectroscopic Evidence of Efficient Generation of Dicopper Intermediate in Selective Catalytic Reduction of NO over Cu-Ion-Exchanged Zeolites
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DOI：
10.1021/acscatal.0c03425
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发表时间：
2020-10-16
期刊：
影响因子：
12.9
通讯作者：
Satsuma, Atsushi
中科院分区：
文献类型：
--
作者：
Oda, Akira;Shionoya, Hitomi;Satsuma, Atsushi
氨选择性催化还原（NH3-SCR）中的关键反应位点是包封在沸石催化剂中的Cu（II）/Cu（I）氨络合物。在重要的Cu-I -> Cu-II再氧化步骤中的反应中间体已被提议为双铜物种。然而，在NH3-SCR下获得双铜中间体的确定性光谱探针仍然是一个相当具有挑战性的课题。在这里，我们报告的光谱证据的高效生成的二铜中间体在NH 3-SCR的铜离子交换沸石。使用光纤UV-vis-NIR光谱分析了在NH3-SCR条件下Cu离子的状态;检测到（μ-η（2）：η（2）-过氧）二铜（II）中间体的独特光谱指纹。我们的光谱分配是合理的密度泛函理论计算。二聚铜的光谱指纹的强度远高于先前报道的预期，并且还发现这种光谱探针仅在NH3-SCR条件下可观察到。这一发现有力地支持了先前提出的Cu对NH3-SCR催化的动态贡献。
The key reactive sites in the selective catalytic reduction (SCR) of NO using ammonia (NH3-SCR) are the Cu(II)/Cu(I) ammine complexes encapsulated within zeolite catalysts. The reaction intermediate in the important Cu-I -> Cu-II reoxidation step has been proposed as the dicopper species. However, obtaining the definitive spectroscopic probe for the dicopper intermediate under NH3-SCR remains a quite challenging subject. Here we report spectroscopic evidence of the efficient generation of the dicopper intermediate in NH3-SCR over Cu-ion-exchanged zeolites. The state of the Cu ion under the NH3-SCR condition was analyzed using fiber-optic UV-vis-NIR spectroscopy; a distinct spectroscopic fingerprint of the (mu-eta(2):eta(2)-peroxo)dicopper(II) intermediate was detected. Our spectroscopic assignment was rationalized by density functional theory calculations. The intensity of the spectroscopic fingerprints of dimeric copper was much higher than expected from previous reports, and it was also found that such a spectroscopic probe is observable only under the NH3-SCR conditions. This finding strongly supports the previously suggested Cu dynamic contributions to NH3-SCR catalysis.