The effect of cyano groups on the solubility of carbon dioxide in ionic liquids containing cyano groups in anion

초록

The solubility of carbon dioxide (CO2) was investigated using three ionic liquids containing different numbers of cyano groups in the anion, 1-hexyl-3-methylimidazolium tricyanomethanide ([c6mim][C(CN)(3)]), 1-hexyl-3-methylimidazolium dicyanamide ([c(6)mim][N(CN)(2)]), and 1-hexyl-3-methylimidazolium thiocyanate ([c(6)mim][SCN]). The CO2 solubilities were determined by measuring the bubble point pressures of the CO2+ionic liquid mixtures at temperatures ranging from 303.15 to 373.15 K and pressure up to 105MPa. The experimental results showed that the solubilities of CO2 in ionic liquids increased with pressure, decreased with temperature, and increased with the length of the alkyl chains in the cation. Furthermore, a higher CO2 solubility was achieved in the ionic liquid with more cyano groups in the anion. The experimental data were correlated with the Peng-Robinson equation of state (PR-EoS), using the conventional van der Waals one fluid mixing rule and the modified Lydersen-Joback-Reid method. The average absolute deviation values of pressure (AAD-P) were 0.0658 for CO2+[c(6)mim][SCN], 0.0633 for CO2+[c(6)mim][N(CN)(2)], and 0.0761 for CO2+[c(6)mim][C(CN)(3)] system.

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