Molecular Dynamics Simulation Study on CO2 Physical Absorption Mechanisms for Ethylene-Glycol-Based Solvents Using Free Energy Calculations

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• 作者：Ryo Nagumo ; Yukihiro Muraki ; Shuichi Iwata ; Hideki Mori ; Hiromitsu Takaba ; Hidetaka Yamada
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2016
• 出版时间：July 27, 2016
• 年：2016
• 卷：55
• 期：29
• 页码：8200-8206
• 全文大小：482K
• 年卷期：0
• ISSN：1520-5045

文摘

Molecular mechanisms of CO₂ physical absorption are significant for the development of higher-performance CO₂ absorbents. In this study, the free energy profiles for CO₂ approaching several types of ethylene glycol (EG)-based solvent molecules and their derivatives (diols, ethers, and alkanes, etc.) were evaluated using molecular dynamics simulations. A desolvation barrier appeared in the free energy profiles in the pure component solvent, corroborating the negative contribution of a void effect on CO₂ affinities. The profiles in vacuum were also estimated to investigate the functional group effects in a constituent solvent molecule. The profiles for the EG-based solvent molecules showed similar minimum values to their derivative diols, while the values for their derivative ethers and alkanes were markedly higher. CO₂ solubility is certainly determined by two major factors: the specific CO₂ affinities of the constituent hydroxyl groups and a steric void effect near an absorbed CO₂ molecule.