硫掺杂碳纳米管催化单乙醇胺溶液解吸CO_(2)机理的理论研究  

Theoretical study on the catalysis mechanism of sulfur-doped carbon nanotubes in CO_(2)desorption from monoethanolamine solution

作　　者：任莹莹 刘均隆 成怀刚 高阳艳 REN Yingying;LIU Junlong;CHENG Huaigang;GAO Yangyan(Institute of Resource and Environmental Engineering,Shanxi University,Taiyuan 030006,China)

机构地区：[1]山西大学资源与环境工程研究所CO_(2)减排与资源化利用教育部工程研究中心,山西太原030006

出　　处：《燃料化学学报（中英文）》2024年第10期1529-1537,共9页Journal of Fuel Chemistry and Technology

基　　金：国家自然科学基金(21707083)资助。

摘　　要：醇胺法吸收CO_(2)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CO_(2)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CO_(2)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CO_(2)的释放。本工作旨在通过CO_(2)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 CO_(2)absorption by alkanolamine solution has been applied industrially because of its excellent efficiency.However,the energy consumption for CO_(2)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 CO_(2)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 CO_(2).It aims to provide

关 键 词：掺杂调控 碳纳米管 催化MEA解吸CO_(2)机理 DFT计算 

分 类 号：O64[理学—物理化学]