Pyrolysis is an efficient and economical method for the utilization of waste rubber, but the high sulfur content limits its industrial application. Currently, the migration and transformation of the element S during pyrolysis of waste rubber is far from well known. In this work, a density functional theory (DFT) method was employed to explore the possible formation pathways of H₂S and its precursors (radicals HS · and S ·) during the pyrolysis of thiophene, which is an important primary pyrolytic product of rubber. In particular, the influence of reactive hydrogen radicals was carefully investigated in the thiophene pyrolysis process. The calculation results indicate that the decomposition of thiophene tends to be initiated by hydrogen transfer between adjacent carbon atoms, which needs to overcome an energy barrier of 312.4 kJ/mol. The optimal pathway to generate H₂S in thiophene pyrolysis involves initial H migration and S-C bond cleavage, with an overall energy barrier of 525.8 kJ/mol. In addition, a thiol intermediate that bears unsaturated C-C bonds is essential for thiophene pyrolysis to generate H₂S, which exists in multiple critical reaction pathways. Moreover, the presence of hydrogen radicals significantly changes the decomposition patterns and reduces the energy barriers for thiophene decomposition, thus promoting the formation of H₂S. The current work on H₂S formation from thiophene can provide some theoretical support to explore clean utilization technologies for waste rubber.

热解是一种利用废橡胶的有效而经济的方法，但是高硫含量限制了其工业应用。当前，在废橡胶的热解过程中元素S的迁移和转变还很不为人所知。在这项工作中，采用密度泛函理论（DFT）方法探索H ₂可能的形成途径噻吩热解过程中的S及其前体（自由基HS·和S·），噻吩是橡胶的重要初级热解产物。特别地，在噻吩热解过程中仔细研究了反应性氢自由基的影响。计算结果表明，噻吩的分解倾向于由相邻碳原子之间的氢转移引发，这需要克服312.4 kJ / mol的能垒。在噻吩热解中生成H ₂ S的最佳途径涉及初始H迁移和SC键裂解，总能垒为525.8 kJ / mol。此外，具有不饱和CC键的硫醇中间体对于噻吩热解生成H ₂是必不可少的。S，存在于多个关键反应路径中。此外，氢自由基的存在显着改变了分解模式并减少了噻吩分解的能垒，从而促进了H ₂ S的形成。目前由噻吩形成H ₂ S的工作可以为探索清洁利用技术提供一些理论支持。用于废旧橡胶。