Effect of cation alkyl chain length on liquid-liquid equilibria of {ionic liquids + thiophene + heptane}: COSMO-RS prediction and experimental verification

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• 作者：Zhen Song ; Jingjing Zhang ; Qian Zeng ; Hongye Cheng ; Lifang Chen ; Zhiwen Qi ; ^{zwqi@ecust.edu.cn" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Cation alkyl chain length effect ; Extractive desulfurization ; COSMO-RS ; Ionic liquids [CnMIM][OAc] ; Liquid-liquid equilibria
• 刊名：Fluid Phase Equilibria
• 出版年：2016
• 出版时间：15 October 2016
• 年：2016
• 卷：425
• 期：Complete
• 页码：244-251
• 全文大小：817 K

文摘

When selecting ionic liquid (IL) as solvent for extraction processes, the cation alkyl chain length is an important structural variation, while research particularly concerning its effect is lacking. In this work, the effect of cation alkyl chain length on the liquid-liquid equilibria of {IL + thiophene + heptane}, an example for extractive desulfurization, was systematically investigated. The COSMO-RS model was employed to calculate the distributional coefficient (β^∞) and selectivity (S^∞) at infinite dilution for thiophene of the combinations of 17 cations and 63 anions. Two different anion-dependent tendencies of the β^∞ with increasing the cation alkyl chain length were identified and analyzed by COSMO-RS theory. To verify the scarcely-reported decreasing β^∞ with longer cation alkyl chain, acetate ([OAc]⁻) was selected as representative and liquid-liquid equilibria {[C_nMIM][OAc] + thiophene + heptane} (n = 2, 4, 6, 8) were experimentally determined, which validate the anion-dependency and demonstrate the highest extraction performance of [C₂MIM][OAc].