Formation of Sulfur Species from Thiophene Decomposition and the Impact of Alkali Metal Ions: A Density Functional Theory Study
Formation of Sulfur Species from Thiophene Decomposition and the Impact of Alkali Metal Ions: A Density Functional Theory Study
复制标题
DOI：
10.1021/acs.energyfuels.3c04094
复制
发表时间：
2024-01
期刊：
影响因子：
--
通讯作者：
Ji Liu;Yuan-gu Xia;Huai-de Sun;Bin Hu;Qiang Lu
中科院分区：
文献类型：
--
作者：
Ji Liu;Yuan-gu Xia;Huai-de Sun;Bin Hu;Qiang Lu
热解是一种有效利用含s有机固体废物生产高附加值化学品和燃料的方法，但同时也会产生气态污染物（如H2S和COS）。热解气体中硫选择性转化为H2S有利于提高液固产物质量，有利于硫的进一步管理。然而，含s气的形成机理，特别是广泛存在的碱金属的影响机理尚不清楚。本文以噻吩为模型化合物，结合密度泛函理论（DFT）、动力学计算和波函数分析，研究了含S自由基/气体（S、SH、CS自由基和H2S）的形成途径。仔细研究了K+和Na+对含s物种形成的影响，以阐明H2S的富集方法。噻吩分解优先由1,2-氢转移反应初始化。含S物种的形成竞争力顺序为SH自由基≈H2S > CS自由基≈S自由基，表明H2S相对于CS自由基形成的COS和cs2具有优势。碱金属离子能增强噻吩的分解，有利于通过增强氢转移反应直接生成H2S和S自由基。在K+和Na+的存在下，SH自由基的生成路径明显增强，CS自由基的形成受到抑制。因此，碱金属离子有利于H2S在气相的直接和间接生成和富集。强化H2S生成方法的阐明，可为热解气体中H2S的废转值利用奠定理论基础。
Pyrolysis is an efficient utilization method for S-containing organic solid wastes to produce value-added chemicals and fuels but is accompanied by gaseous pollutants (e.g., H2S and COS). The selective transformation of sulfur to H2S in the pyrolysis gas will be beneficial for the quality improvement of liquid and solid products, as well as the further management of sulfur. However, the S-containing gas formation mechanism, especially the influence mechanism of widely presented alkali metals, is still unclear. Herein, the formation pathways of S-containing radicals/gases (S, SH, CS radicals, and H2S) was investigated by combining density functional theory (DFT), kinetic calculations, and wave function analysis with thiophene as the model compound. The impact of K+and Na+on S-containing species formation was carefully studied to elucidate the enrichment method for H2S. Thiophene decomposition is preferentially initialized by the 1,2-hydrogen transfer reaction. The formation competitiveness of S-containing species is in the order SH radical ≈ H2S > CS radical ≈ S radical, indicating the dominance of H2S compared with those of COS and CS2formed through CS radicals. Alkali metal ions can enhance the decomposition of thiophene and are beneficial to the direct formation of H2S and S radicals through enhanced hydrogen transfer reactions. An inferior generation path of SH radicals is significantly enhanced, and the CS radical formation is inhibited in the presence of K+and Na+. Consequently, alkali metal ions are conducive to direct and indirect generation and enrichment of H2S in the gas phase. The elucidation of the enhanced H2S formation method can lay a theoretical basis for the waste-to-value utilization of H2S in the pyrolysis gas.