Low-temperature NH3 abatement via selective oxidation over a supported copper catalyst with high Cu+ abundance.
Low-temperature NH3 abatement via selective oxidation over a supported copper catalyst with high Cu+ abundance.
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DOI：
10.1016/j.jes.2023.05.047
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发表时间：
2023-06
影响因子：
6.9
通讯作者：
Zhiming Yang;Lin Peng;Leneng Yang;Mingli Fu;D. Ye;Peirong Chen
中科院分区：
文献类型：
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作者：
Zhiming Yang;Lin Peng;Leneng Yang;Mingli Fu;D. Ye;Peirong Chen
选择性催化NH_3-SCO(NH3-SCO)技术在减少固定烟气后处理装置的NH_3排放方面具有广阔的应用前景。然而，由于缺乏低成本、高活性和高氮气选择性的催化剂，限制了其实际应用。在这里，我们以富缺陷氮掺杂碳纳米管(NCNT-AW)为载体，开发了一种高活性、高耐久的铜基NH3-SCO催化剂。在NH3-SCO反应中，制得的铜/NCNT-AW催化剂的aT50(即达到50%NH3转化率的温度)为174°C，表现出优异的催化活性，不仅优于无氮氧官能化碳纳米管(OCNTs)或表面缺陷较少的NCNT负载的铜催化剂，而且也优于公开文献中活性最高的铜催化剂。反应动力学测量和以NH3为探针分子的程序升温表面反应表明，NH3-SCO在Cu/NCNT-AW上的反应遵循以一氧化氮(NO)为关键中间体的内选择性催化反应(I-SCR)途径。X射线光电子能谱、拉曼光谱和X射线吸收光谱的机理研究表明，Cu/NCNT-AW优异的NH3-SCO性能源于表面缺陷和N掺杂的协同作用。具体地说，表面缺陷促进了CuO纳米粒子在含N中心的锚定，从而使电子从N到CuO的有效转移，显著增加了催化剂中SCR活性的Cu+中心的比例。本研究提出了一种利用碳表面缺陷和氮掺杂的相互作用来制备富铜铜催化剂的新思路，并通过选择氧化有效地减少了滑脱NH3的排放。
Selective catalytic NH3-to-N2oxidation (NH3-SCO) is highly promising for abating NH3emissions slipped from stationary flue gas after-treatment devices. Its practical application, however, is limited by the non-availability of low-cost catalysts with high activity and N2selectivity. Here, using defect-rich nitrogen-doped carbon nanotubes (NCNT-AW) as the support, we developed a highly active and durable copper-based NH3-SCO catalyst with a high abundance of cuprous (Cu+) sites. The obtained Cu/NCNT-AW catalyst demonstrated outstanding activity with aT50(i.e.the temperature to reach 50% NH3conversion) of 174°C in the NH3-SCO reaction, which outperformed not only the Cu catalyst supported on N-free O-functionalized CNTs (OCNTs) or NCNT with less surface defects, but also those most active Cu catalysts in open literature. Reaction kinetics measurements and temperature-programmed surface reactions using NH3as a probe molecule revealed that the NH3-SCO reaction on Cu/NCNT-AW follows aninternalselective catalytic reaction (i-SCR) route involving nitric oxide (NO) as a key intermediate. According to mechanistic investigations by X-ray photoelectron spectroscopy, Raman spectroscopy, and X-ray absorption spectroscopy, the superior NH3-SCO performance of Cu/NCNT-AW originated from a synergy of surface defects and N-dopants. Specifically, surface defects promoted the anchoring of CuO nanoparticles on N-containing sites and, thereby, enabled efficient electron transfer from N to CuO, increasing significantly the fraction of SCR-active Cu+sites in the catalyst. This study puts forward a new idea for manipulating and utilizing the interplay of defects and N-dopants on carbon surfaces to fabricate Cu+-rich Cu catalysts for efficient abatement of slip NH3emissions via selective oxidation.