Solvent properties of functionalized ionic liquids for CO2 absorption

Ionic liquids can be used as solvents for gas absorption operations in order to improve the process economy and general efficiency of gas separations. This work investigates solvent properties of ionic liquids and compares them to amine solutions used for absorption of carbon dioxide (CO2). The CO2 solubility into six different room temperature ionic liquids (RTILs) was measured at temperatures between 298 K and 343 K and pressures up to about 1 MPa. The RTILs used were: [bmim]+[BF4]−, [bmim]+[DCA]−, and four imidazolium-based ionic liquids paired with [DCA] and [BF4], in which the cation was functionalized with either a primary, tertiary amine or a hydroxyl group. The density, viscosity and surface tension of the studied RTILs were measured at temperatures ranging from 293 K up to 363 K. The results showed that CO2 absorption behaviour was influenced by the functionalized chains appended to the RTILs cation. A chemical enhancement of the CO2 absorption was observed when functionalized RTILs were used as absorption solvents. It was possible to increase the ionic liquid volumetric gas load almost threefold by attaching functional groups to the ionic liquid, whereas for the traditional amine solutions the maximum gas load is stoichiometrically limited.

[1]  P. Wasserscheid.  Chemistry: Volatile times for ionic liquids , 2006, Nature.

[2]  A. Heintz.  Recent developments in thermodynamics and thermophysics of non-aqueous mixtures containing ionic liquids. A review , 2005 .

[3]  N. Kuipers,et al.  Synthesis and Evaluation of Metal−Ligand Complexes for Selective Olefin Solubilization in Reactive Solvents , 2005 .

[4]  A. Yokozeki,et al.  Solubilities and Diffusivities of Carbon Dioxide in Ionic Liquids: [bmim][PF6] and [bmim][BF4] , 2005 .

[5]  Sheng Dai,et al.  Examination of the Potential of Ionic Liquids for Gas Separations , 2005 .

[6]  T. Welton.  Ionic liquids in catalysis , 2004 .

[7]  T. Vandernoot,et al.  Temperature dependence of viscosity for room temperature ionic liquids , 2004 .

[8]  Joan F. Brennecke,et al.  Thermophysical Properties of Imidazolium-Based Ionic Liquids , 2004 .

[9]  J. Brennecke,et al.  Phase Equilibria of Gases and Liquids with 1-n-butyl-3-Methylimidazolium Tetrafluoroborate , 2003 .

[10]  R. Sheldon,et al.  Biocatalytic transformations in ionic liquids. , 2003, Trends in biotechnology.

[11]  辰巳 敬.  Journal of Molecular Catalysis A--Chemical,Catalysis Communications (特集 触媒研究と学術雑誌/情報) , 2002 .

[12]  Edward S Rubin,et al.  A technical, economic, and environmental assessment of amine-based CO2 capture technology for power plant greenhouse gas control. , 2002, Environmental science & technology.

[13]  H. Olivier-Bourbigou,et al.  Ionic liquids: perspectives for organic and catalytic reactions , 2002 .

[14]  Martin A. Abraham,et al.  Clean solvents : alternative media for chemical reactions and processing , 2002 .

[15]  K. Seddon,et al.  Viscosity and Density of 1-Alkyl-3-methylimidazolium Ionic Liquids , 2002 .

[16]  P. Watson,et al.  Surface orientation in ionic liquids , 2001 .

[17]  K. Seddon,et al.  Influence of chloride, water, and organic solvents on the physical properties of ionic liquids , 2000 .

[18]  H. Olivier.  Recent developments in the use of non-aqueous ionic liquids for two-phase catalysis , 1999 .

[19]  Paitoon Tontiwachwuthikul,et al.  Research and development activities on high efficiency separation process technologies for carbon dioxide removal from industrial sources at University of Regina, Canada , 1996 .

[20]  A. Chakma,et al.  An energy efficient mixed solvent for the separation of CO2 , 1995 .

[21]  K. Henry,et al.  Viscosity, Density, and Surface Tension of Binary Mixtures of Water and N-Methyldiethanolamine and Water and Diethanolamine and Tertiary Mixtures of These Amines with Water over the Temperature Range 20-100.degree.C , 1994 .

[22]  Alan E. Mather,et al.  Solubility of carbon dioxide in aqueous diethanolamine solutions at high pressures , 1972 .

[23]  M. Maase,et al.  Biphasic acid scavenging utilizing ionic liquids : The first commercial process with ionic liquids , 2005 .

[24]  James H. Davis.  Task-specific ionic liquids for separations of petrochemical relevance : Reactive capture of CO2 using amine-incorporating ions , 2005 .

[25]  G. W. Meindersma,et al.  Ionic Liquids as Alternatives to Organic Solvents in Liquid-Liquid Extraction of Aromatics , 2005 .

[26]  Peter Wasserscheid,et al.  Ionic Liquids in Synthesis , 2002 .

[27]  Robin D. Rogers,et al.  Characterization and comparison of hydrophilic and hydrophobic room temperature ionic liquids incorporating the imidazolium cation , 2001 .

[28]  Axel Meisen,et al.  Research and development issues in CO2 capture , 1997 .

[29]  G. Versteeg,et al.  Solubility and diffusivity data for the absorption of carbonyl sulfide, carbon dioxide, and nitrous oxide in amine solutions , 1992 .

[30]  K. Shen,et al.  Solubility of carbon dioxide in aqueous mixtures of monoethanolamine with methyldiethanolamine , 1992 .

[31]  Geert Versteeg,et al.  A study on the reaction between CO2 and alkanolamines in aqueous solutions , 1983 .

[32]  Lianwei Wang,et al.  Journal of Electroanalytical Chemistry , 1960, Nature.

[33]  A. Adamson.  Physical chemistry of surfaces , 1960 .