State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, 163 Xianlin Avenue, Nanjing, 210023, China.
State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, 163 Xianlin Avenue, Nanjing, 210023, China; Shenzhen Research Institute of Nanjing University, Shenzhen, 518057, China.
Environ Res. 2023 Dec 1;238(Pt 1):117176. doi: 10.1016/j.envres.2023.117176. Epub 2023 Sep 18.
Although nonthermal plasma (NTP) technology has high removal efficiency for volatile organic compounds (VOCs), it has limited carbon dioxide (CO) selectivity, which hinders its practical application. In this study, α-MnO nanorods with tunable oxygen vacancies and hydroxyl groups were synthesized by two-step hydrothermal process to enhance their activity for deep oxidation of toluene. Hydrochloric acid (HCl) was used to assist in synthesis of α-MnO nanorods with tunable oxygen vacancies, furtherly, more hydroxyl groups were introduced to HCl-assisted synthesized α-MnO by K supplement. The results showed that the as-synthesized nanorods exhibited superior activity, improved by nearly 30% removal efficiency of toluene compared to pristine MnO at SIE = 339 J/L, and reaching high CO selectivity of 72% at SIE = 483 J/L, successfully promoting the deep oxidation of toluene. It was affirmed that oxygen vacancies played an important role in toluene conversion, improving the conversion of ozone (O) and resulting in higher mobility of surface lattice oxygen species. Besides, the enhancement of deep oxidation performance was caused by the increase of hydroxyl groups concentration. In-situ DRIFTS experiments revealed that the adsorbed toluene on catalyst surface was oxidized to benzyl alcohol by surface lattice oxygen, and hydroxyl groups were also found participating in toluene adsorption. Overall, this study provides a new approach to designing catalysts for deep oxidation of VOCs.
虽然非热等离子体（NTP）技术对挥发性有机化合物（VOCs）具有很高的去除效率，但对二氧化碳（CO）的选择性有限，这限制了其实际应用。在这项研究中，通过两步水热法合成了具有可调氧空位和羟基的α-MnO 纳米棒，以提高其对甲苯的深度氧化活性。盐酸（HCl）用于辅助合成具有可调氧空位的α-MnO 纳米棒，进一步通过 K 补充引入更多的羟基到 HCl 辅助合成的α-MnO 中。结果表明，与原始 MnO 相比，所合成的纳米棒在 SIE = 339 J/L 时表现出优异的活性，甲苯去除效率提高了近 30%，在 SIE = 483 J/L 时达到了高 CO 选择性 72%，成功促进了甲苯的深度氧化。氧空位在甲苯转化中起着重要作用，提高了臭氧（O）的转化率，导致表面晶格氧物种的迁移率更高，这一点得到了证实。此外，羟基浓度的增加也是深度氧化性能增强的原因。原位 DRIFTS 实验表明，催化剂表面吸附的甲苯被表面晶格氧氧化为苯甲醇，同时也发现羟基参与了甲苯的吸附。总的来说，这项研究为设计 VOCs 深度氧化催化剂提供了一种新方法。
