A low-viscosity family of ionic liquids based on the tetracyanoborate anion for CO2 capture

The extraordinary properties of ionic liquids (ILs) such as their negligible vapor pressure have placed them in the spotlight of researchers as alternative solvents for separation processes. The large number of anion/cation combinations allows the possibility of "designing" ILs according to the specifications required for the process. ILs should be chemically and thermally stable. When used for gas purification and carbon dioxide (CO2) capture, ILs are required to have a high CO2 absorption capacity and low viscosity. The newly task-specific ILs achieve higher CO2 loadings at moderate pressures, also at supercritical conditions. However, the relatively high viscosity of some ILs is a drawback for their practical application, in spite of their high gas solubility. The aim of this work is to study the feasibility of using tetracyanoborate-based ionic liquid for CO2 capture. The main characteristic of this family of ILs is their low viscosity compared to "traditional" ionic liquids, such as tetrafluoroborate or hexafluoroborate. We will present some pure component properties such as viscosity, density and surface tension, as well as solubility measurements of the binary systems IL+ CO2. The solubility of CO2 in 1-ethyl-3-methylimidazolium tetracyanoborate [emim][TCB] and 1-hexyl-3-methylimidazolium tetracyanoborate [hmim][TCB] was measured using the Cailletet apparatus where the bubble point was visually determined. The encouraging results show that the tetracyanoborate ionic liquids have a large potential for CO2 absorption applications

A low-viscosity family of ionic liquids based on the tetracyanoborate anion for CO2 capture

The extraordinary properties of ionic liquids (ILs) such as their negligible vapor pressure have placed them in the spotlight of researchers as alternative solvents for separation processes. The large number of anion/cation combinations allows the possibility of "designing" ILs according to the specifications required for the process. ILs should be chemically and thermally stable. When used for gas purification and carbon dioxide (CO2) capture, ILs are required to have a high CO2 absorption capacity and low viscosity. The newly task-specific ILs achieve higher CO2 loadings at moderate pressures, also at supercritical conditions. However, the relatively high viscosity of some ILs is a drawback for their practical application, in spite of their high gas solubility. The aim of this work is to study the feasibility of using tetracyanoborate-based ionic liquid for CO2 capture. The main characteristic of this family of ILs is their low viscosity compared to "traditional" ionic liquids, such as tetrafluoroborate or hexafluoroborate. We will present some pure component properties such as viscosity, density and surface tension, as well as solubility measurements of the binary systems IL+ CO2. The solubility of CO2 in 1-ethyl-3-methylimidazolium tetracyanoborate [emim][TCB] and 1-hexyl-3-methylimidazolium tetracyanoborate [hmim][TCB] was measured using the Cailletet apparatus where the bubble point was visually determined. The encouraging results show that the tetracyanoborate ionic liquids have a large potential for CO2 absorption applications

Immobilization of Ionic Liquids, Types of Materials, and Applications

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High pressure solubility of methane in the ionic liquid 1-hexyl-3-methylimidazolium tricyanomethanide

In this paper, new experimental measurements of methane (CH4) solubility in the ionic liquid (IL) 1-hexyl-3-methylimidazolium tricyanomethanide ([hmim][TCM]) are presented. The solubility data were obtained using a synthetic method based on bubble-point pressure measurements for concentrations ranging from (2–10) CH4 mole% and within a temperature range of (293–363 K) and pressures up to 10 MPa. The results obtained in this work were compared with those obtained for other ILs. The IL [hmim][TCM] was found to show the lowest CH4 solubility, which is desired for application of this IL as gas sweetening solvent (low co-absorption of hydrocarbons). Moreover, the CH4 solubility was compared to the CO2 solubility in the same IL, showing that [hmim][TCM] can selectively absorb CO2 from natural gas. The experimental solubility data of CH4 in [hmim][TCM] were accurately modeled using the PR-EoS with only one temperature-independent binary interaction parameter