High pressure phase behavior of carbon dioxide in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide and 1-butyl-3-methylimidazolium dicyanamide ionic liquids Export

@article{citeulike:4807792, abstract = {The acidity/basicity of the reaction media has a substantial influence on the efficiency of many reactive processes; therefore, a new class of acidic or basic ionic liquids is gaining special attention due to the possibility of increasing the efficiency of many processes by a wise manipulation of their properties. The absorption of sour gases is one of the processes that can be enhanced by the basic character of the ionic liquid. The fluorination of the cation or anion can also contribute to the gas solubility enhancement. In this work, these two characteristics are evaluated and compared through the study of gas–liquid equilibrium of two ionic liquids, 1-butyl-3-methylimidazolium dicyanamide ([C 4 mim][DCA]) and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C 4 mim][Tf 2 N]), with carbon dioxide (CO 2 ) at temperatures up to 363 K and pressures up to 74 MPa. A thermodynamic model based on the Peng–Robinson equation of state with the Wong–Sandler mixing rule, using the UNIQUAC model for the activity coefficients, was used to describe the experimental data and for the estimation of the Henry's constants. The solubility of CO 2 in 1-butyl-3-methylimidazolium dicyanamide is much lower than anticipated on the basis of the reported p K a of the anion when compared with the acetate anion. No chemisorption is observed and the solvation enthalpy is quite low, ruling out any Lewis acid/base interaction between the anion and the CO 2 . The 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid, known to present one of the highest solubilities towards CO 2 due to the presence of fluoroalkyl groups, showed a much larger solubility for CO 2 than 1-butyl-3-methylimidazolium dicyanamide.}, author = {Carvalho, Pedro J. and \'{A}lvarez, V\'{\i}ctor H. and Marrucho, Isabel M. and Aznar, Mart\'{\i}n and Coutinho, Jo\~{a}o A. P.}, citeulike-article-id = {4807792}, citeulike-linkout-0 = {http://dx.doi.org/10.1016/j.supflu.2009.05.008}, citeulike-linkout-1 = {http://linkinghub.elsevier.com/retrieve/pii/S0896844609001946}, day = {08}, doi = {10.1016/j.supflu.2009.05.008}, issn = {08968446}, journal = {The Journal of Supercritical Fluids}, keywords = {behaviour, carbondioxide, highpressure, phase, rtil}, month = {September}, number = {2}, pages = {105--111}, posted-at = {2009-07-03 13:33:55}, priority = {4}, title = {High pressure phase behavior of carbon dioxide in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide and 1-butyl-3-methylimidazolium dicyanamide ionic liquids}, url = {http://dx.doi.org/10.1016/j.supflu.2009.05.008}, volume = {50}, year = {2009} }

TY - JOUR ID - citeulike:4807792 L3 - citeulike-article-id:4807792 N2 - The acidity/basicity of the reaction media has a substantial influence on the efficiency of many reactive processes; therefore, a new class of acidic or basic ionic liquids is gaining special attention due to the possibility of increasing the efficiency of many processes by a wise manipulation of their properties. The absorption of sour gases is one of the processes that can be enhanced by the basic character of the ionic liquid. The fluorination of the cation or anion can also contribute to the gas solubility enhancement. In this work, these two characteristics are evaluated and compared through the study of gas–liquid equilibrium of two ionic liquids, 1-butyl-3-methylimidazolium dicyanamide ([C 4 mim][DCA]) and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C 4 mim][Tf 2 N]), with carbon dioxide (CO 2 ) at temperatures up to 363 K and pressures up to 74 MPa. A thermodynamic model based on the Peng–Robinson equation of state with the Wong–Sandler mixing rule, using the UNIQUAC model for the activity coefficients, was used to describe the experimental data and for the estimation of the Henry's constants. The solubility of CO 2 in 1-butyl-3-methylimidazolium dicyanamide is much lower than anticipated on the basis of the reported p K a of the anion when compared with the acetate anion. No chemisorption is observed and the solvation enthalpy is quite low, ruling out any Lewis acid/base interaction between the anion and the CO 2 . The 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ionic liquid, known to present one of the highest solubilities towards CO 2 due to the presence of fluoroalkyl groups, showed a much larger solubility for CO 2 than 1-butyl-3-methylimidazolium dicyanamide. IS - 2 JF - The Journal of Supercritical Fluids SN - 08968446 EP - 111 TI - High pressure phase behavior of carbon dioxide in 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide and 1-butyl-3-methylimidazolium dicyanamide ionic liquids VL - 50 SP - 105 KW - behaviour KW - carbondioxide KW - highpressure KW - phase KW - rtil AU - Carvalho, Pedro AU - Álvarez, Víctor AU - Marrucho, Isabel AU - Aznar, Martín AU - Coutinho, João PY - 2009/09/08/ UR - http://dx.doi.org/10.1016/j.supflu.2009.05.008 ER -