Measurement And Calculation Of Gas Solubility In Ionic Liquid

Ionic liquid is considered as “green” solvent,which can be substitute of conventional organic solvents.Solubilities of gases in ionic liquid,viscosities and densities of ionic liquids are necessary for application of ionic liquids in absorption and storage of gases.Now,A huge amount of ionic liquid have been synthesized or potentially synthesized.How to find the ionic liquid with highest solubilty for gases is the problem wihch we should solve before using ionic liquid for absorption and storage of gases.In addtion,the high viscosities of ionic liquids limit the application of ionic liquids,how to reduce the viscosities of ionic liquids is one of the critical problem.Therefore,we firstly found the ionic liquid with highest solubilty for gases commonly used in industry by the quantum chemistry method.Then theoretical and experimental study on solubilities of gases in it,its viscosities and densities are performed,and the mothods for reduing the viscosities of ionic liquids are investigated.The main contents and conclusions in this work are as follows: 1.Henry's constants for carbon dioxide,oxygen,krypton,methane,ethane,ethylene,propane in 665 ionic liquids were calculated using COSMO-RS method.After screening,it can be found that the solubilities of all the gases in [P(14)666][TMPP] are the highest.2.A experimental system based on the isochoric-saturation method was built,and the reliability of the system was verified.The solubilities of carbon dioxide,oxygen,krypton,methane,ethane,ethylene,propane in [P(14)666][TMPP] were measured using the experimental system for gas solubility.After doing a comparison,it can be found that [P(14)666][TMPP] has higher solubilities for these gases than other ionic liquids in literatures,and different from other ionic liquids in literatures,[P(14)666][TMPP] has higher solubility for ethane than that for ethylene.3.The viscosities and densities of four tetralkylphosphonium bis(2,4,4-trimethylpentyl)phosphinates [P(14)666][TMPP],[P4444][TMPP],[P1444][TMPP] and [P8111][TMPP] were measured using viscosimeter based on the rotation method and densimeter based on vibrating tube method,respectively.Different from other ionic liquids in literatures,the viscosity of tetralkylphosphonium bis(2,4,4-trimethylpentyl)phosphinate does not increase when the number of carbon atom in the alkyl chains on the cation increases,and the density does not decrease when the number of carbon atom in the alkyl chains on the cation increases.A low viscosity ionic liquid [BHMIM][AC] was used as diluent for reducing the large viscosity of [P(14)666][TMPP].Addition of some [BHMIM][AC] in [P(14)666][TMPP] can give a dramatic drop in the viscosity of [P(14)666][TMPP] and the mixture still has high solubilities for carbon dioxide,oxygen,krypton,methane,ethane,ethylene,propane.4.The Krichevsky-Kasarnovsky equation was modified in order to improve its predictive ability.A mixing rule was presented to extend the Krichevsky-Kasarnovsky equation to solubility of gas in mixture of ionic liquids.The results calculated from the modified Krichevsky-Kasarnovsky equation for solubilities of carbon dioxide,oxygen,krypton,methane,ethane,ethylene,propane in [P(14)666][TMPP],[P4444][TMPP],[P8111][TMPP] and mixtures of [BHMIM][AC] and [P(14)666][TMPP] agree well with the experiment.