Tian Rui, Lu Jichang, Xu Zhizhi, Zhang Wenjun, Liu Jiangping, Wang Langlang, Xie Yibing, Zhao Yutong, Cao Xiaohua, Luo Yongming
Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming650500, P. R. China.
The Innovation Team for Volatile Organic Compounds Pollutants Control and Resource Utilization of Yunnan Province, Kunming650500, P. R. China.
Environ Sci Technol. 2022 Oct 4. doi: 10.1021/acs.est.2c04033.
The competitive adsorption behavior, the synergistic catalytic reaction, and deactivation mechanisms under double components of sulfur-containing volatile organic compounds (VOCs) are a bridge to solve their actual pollution problems. However, they are still unknown. Herein, simultaneous catalytic decomposition of methyl mercaptan (CHSH) and ethyl mercaptan (CHSH) is investigated over lanthanum (La)-modified ZSM-5, and kinetic and thermodynamic results confirm a great difference in the adsorption property and catalytic transformation behavior. Meanwhile, the new synergistic reaction and deactivation mechanisms are revealed at the molecular level by combining with in situ diffuse reflectance infrared spectroscopy ( DRIFTS) and density functional theory (DFT) calculations. The CHCH* and SH* groups are presented in decomposing CHSH, while the new species of CH*, active H* and S*, instead of CH* and SH*, are proved as the key elementary groups in decomposing CHSH. The competitive recombining of SH* in CHSH with highly active H* in dimethyl sulfide (CHSCH), an intermediate in decomposing CHSH, would aggravate the deposition of carbon and sulfur. La/ZSM-5 exhibits potential environmental application due to the excellent stability of 200 h and water resistance. This work gives an understanding of the adsorption, catalysis, reaction, and deactivation mechanisms for decomposing double components of sulfur-containing VOCs.
含硫挥发性有机化合物（VOCs）双组分体系下的竞争吸附行为、协同催化反应及失活机制是解决其实际污染问题的桥梁。然而，这些机制仍不明确。在此，研究了镧（La）改性ZSM-5上甲硫醇（CH₃SH）和乙硫醇（C₂H₅SH）的同时催化分解，动力学和热力学结果证实了吸附性能和催化转化行为存在很大差异。同时，结合原位漫反射红外光谱（DRIFTS）和密度泛函理论（DFT）计算，在分子水平上揭示了新的协同反应和失活机制。在分解CH₃SH过程中出现了CH₃和SH基团，而在分解C₂H₅SH过程中，新的物种CH*、活性H和S，而非CH₃和SH，被证明是关键的基本基团。CH₃SH中的SH与分解CH₃SH过程中的中间体二甲基硫醚（CH₃SCH₃）中的高活性H竞争重组，会加剧碳和硫的沉积。La/ZSM-5由于具有200 h的优异稳定性和耐水性而展现出潜在的环境应用价值。这项工作有助于理解含硫VOCs双组分分解的吸附、催化、反应和失活机制。
