Modulating active oxygen species on a-MnO 2 with K and Pb for SCR of NO at low temperatures
Modulating active oxygen species on a-MnO 2 with K and Pb for SCR of NO at low temperatures
复制标题
K和Pb调节a-MnO 2 上的活性氧用于NO低温SCR
DOI：
10.1039/d3cy01068f
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发表时间：
2023
影响因子：
5
通讯作者：
Yang G
中科院分区：
文献类型：
--
作者：
Yang G
低温选择性催化还原（SCR）技术是近年来研究的热点。然而，氧空位和活性氧物种在LT SCR过程中的作用仍然不清楚。在这项研究中，我们将表面活性氧物种分为三组：Ong（能够将NH3氧化成氮气），Olg（能够将NH3氧化成笑气）和Ono（能够将NH3氧化成一氧化氮）。在此基础上，研究了Pb和K掺杂对α-MnO 2活性氧物种及其低温SCR性能的影响。结果表明，K掺杂减少了Ono的产生，同时增强了Ong和Olg的产生。相反，Pb掺杂抑制Ong物种的形成，并降低Ono物种生成的温度阈值。因此，K掺杂促进SCR性能，而Pb掺杂改善NH3氧化并降低NOx转化率。密度泛函理论计算结果表明，在MnO 2隧道中掺入K有利于NH3吸附，降低活化能垒，而Pb掺杂则抑制NH3吸附，增加NH3活化能垒。研究结果提供了有价值的洞察活性氧物种和氧空位在低温SCR过程中的作用。
Low-temperature (LT) selective catalytic reduction (SCR) of NOx has been a research hotspot. However, the roles of oxygen vacancies and active oxygen species in the LT SCR process are still unclear. In this study, we categorized surface-active oxygen species into three groups: Ong (capable of oxidizing NH3 into nitrogen gas), Olg (capable of oxidizing NH3 into laughing gas), and Ono (capable of oxidizing NH3 into nitric oxide). Accordingly, the influence of Pb and K doping on the active oxygen species of α-MnO2 and its LT SCR performance were investigated. The results demonstrate that K doping reduces the generation of Ono while enhancing the production of Ong and Olg. In contrast, Pb doping inhibits the formation of Ong species and decreases the temperature threshold for Ono species generation. Thus, K doping facilitated the SCR performance, while Pb doping improved the NH3 oxidation and reduced the NOx conversion. DFT calculations revealed that K incorporated in the tunnels of MnO2 facilitated NH3 adsorption and reduced the energy barrier for activation, while Pb doping inhibited NH3 adsorption and increased the energy barrier for NH3 activation. The findings provide valuable insight into the roles of active oxygen species and oxygen vacancies in the low-temperature SCR process.