Solubilities of Carbon Dioxide and Oxygen in the Ionic Liquids Methyl Trioctyl Ammonium Bis(trifluoromethylsulfonyl)imide, 1-Butyl-3-Methyl Imidazolium Bis(trifluoromethylsulfonyl)imide, and 1-Butyl-3

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• 作者：Indra Bahadur ; Khalid Osman ; Christophe Coquelet ; Paramespri Naidoo ; Deresh Ramjugernath
• 刊名：Journal of Physical Chemistry B
• 出版年：2015
• 出版时间：January 29, 2015
• 年：2015
• 卷：119
• 期：4
• 页码：1503-1514
• 全文大小：435K
• ISSN：1520-5207

文摘

Ionic liquids (ILs) are being considered as solvents for gas absorption processes as they have the potential, in general, for improved efficiency of gas separations, as well as lower capital and operating costs compared to current commercial processes. In this study the solvent properties of ILs are investigated for use in the absorption of carbon dioxide (CO₂) and oxygen (O₂). The absorption of these gases in ILs was measured in the temperature range 303.15鈥?33.15 K and at pressures up to 1.5 MPa by gravimetric analysis. The ILs used were methyl trioctyl ammonium bis (trifluoromethylsulfonyl) imide ([MOA][Tf₂N]), 1-butyl-3-methyl imidazolium bis (trifluoromethylsulfonyl) imide ([BMIM][Tf₂N]), and 1-butyl-3-methyl imidazolium methyl sulfate ([BMIM][MeSO₄]). The measurement technique employed in this study is fast and accurate, and requires small quantities of solvent. The results indicated that absorption of both gases increased with a decrease in operating temperature and an increase in pressure. [MOA][Tf₂N] had the highest CO₂ and O₂ solubility. [BMIM][Tf₂N] was determined to have the highest selectivity for CO₂ absorption. [BMIM][MeSO₄] achieved the lowest CO₂ absorption with a moderate O₂ absorption, revealing this IL to be the least desirable for CO₂ and O₂ absorption. Calculation of Henry鈥檚 law constants for all systems confirmed the deductions made from absorption data analysis. Calculation of enthalpy and entropy of absorption for each system revealed CO₂ absorption in [MOA][Tf₂N] to be the least sensitive to temperature increases. The absorption data was modeled using the generic Redlich鈥揔wong cubic equation of state (RK-EOS) coupled with a group contribution method.