醇胺法吸收CO₂是目前最成熟的碳捕集技术，虽然吸收效率高、稳定性好，但过高的解吸能耗限制其大规模工业推广应用。催化解吸提供了降低CO₂解吸能耗的可能性。本工作利用基于密度泛函理论（DFT）的量子化学模拟方法，探索了硫掺杂碳纳米管（S-CNTs）催化单乙醇胺（MEA）溶液吸收-解吸CO₂反应机理。通过过渡态搜索发现，以S-CNTs为催化剂的解吸过程，决速步骤的反应能垒降低了1.15 kcal/mol。局部态密度（PDOS）分析表明，产物氨基甲酸酯吸附质子化胺MEACOO⁻_MEAH⁺和吸收中间产物MEA⁺COO⁻中的C、N、O原子在CNTs和S-CNTs表面吸附时PDOS差距较大。此外，与未改性CNTs相比，S-CNTs上电荷密度增加，掺杂的硫原子附近碳原子具有明显的电负性。相比于CNTs，吸收中间产物MEA⁺COO⁻和吸收产物MEACOO⁻_MEAH⁺均向S-CNTs转移了更多的电荷，表明更多的电荷转移有利于CO₂的释放。本工作旨在通过CO₂催化解吸机理的研究为催化剂的设计提供一定的理论依据。

The CO₂ absorption by alkanolamine solution has been applied industrially because of its excellent efficiency. However, the energy consumption for CO₂ desorption is high. To reduce the energy consumption, the catalyst is introduced into the alkanolamine capture system. In this study, the catalysis mechanism of sulfur-doped carbon nanotubes (S-CNTs) in CO₂ desorption from monoethanolamine (MEA) solution is explored by simulation based on density-functional theory (DFT) calculations. It was found that compared with the single wall carbon nanotubes (CNTs), the adsorption performance of the key substances in the absorption-desorption process on S-CNTs was different, and the adsorption energy of the reactant MEA was reduced by 1.50 kcal/mol, and the adsorption energy of the absorption intermediates MEACOO⁻_MEAH⁺ was increased by 2.32 kcal/mol, and the adsorption energy of the absorption product carbamate (MEACOO⁻) increased significantly. By transition state searching, energy barrier for the rate-determining step was reduced by 1.15 kcal/mol in the desorption process with S-CNTs as the catalyst, suggesting that S-CNTs contributes to amine regeneration. By observing the Mulliken charge of C atoms in the vicinity of S atoms, it was found that the charge of C atoms changed from electroneutral (0.001 eV) to electronegative (−0.325 eV). The partial density of states (PDOS) of C, N and O atoms from the absorption intermediate MEA⁺COO⁻ and the absorption product MEACOO⁻_MEAH⁺ changes greatly when they adsorbed on CNTs and S-CNTs. In addition, compared with CNTs, the charge density on S-CNTs increases, and the C atoms near the doped S atoms attain obvious electronegativity. Compared with CNTs, the absorption intermediate MEA⁺COO⁻ and the absorption product MEACOO⁻_MEAH⁺ transfer more charges to S-CNTs. This paper is of guiding significance for protecting the environment, maintaining the sustainable development of the energy industry, improving the utilisation rate of raw materials, and reducing the production cost of desorbed CO₂. It aims to provide some theoretical basis for the design of catalysts through the study of the catalysis mechanism of S-CNTs in CO₂ desorption from monoethanolamine solution.