Structural Dependence and Spectroscopic Evidence of Methane Dissolution in Ionic Liquids

Abstract

High methane dissolution capacity in a liquid is important for methane storage and transformation. In this work, methane solubility in different ionic liquids (ILs) was studied and was found associated with IL's structural and physical properties. In imidazolium-based ILs, ILs containing C-F and long alkyl chain showed high methane solubility mainly due to lower surface tension and molar density. Reducing the surface tension of solvent by adding 0.16 mol of trimethyl-1-propanaminium iodide (FC-134) with respect to [Bmim][NTf] increased methane solubility by 39.3%. In situ high-pressure attenuated total reflection Fourier transform infrared spectroscopic results indicated a reversible process of methane dissolution in the ILs. The antisymmetric C-H stretching band of dissolved methane in ILs showed highly prominent rotational-vibrational bands with high intensity and narrow half-peak width compared to gaseous methane. Induced interaction between methane and IL resulted in increased dipole variation strength and reduced methane molecular symmetry. The constant antisymmetric C-H stretching peak at 3016.85 cm revealed an unconstrained methane rotation in the stable physical and chemical environment of IL. Methane insertion into the IL's intranetwork space needs activation energy to overcome the interaction of cation-anion network. Kinetic analysis of methane in [Bmim][NTf] and [Bmim][HSO] at different temperatures indicated that methane dissolution in these two ILs was a reversible first-order and very weak endothermic process and that methane dissolution required high activation energy in ILs with stronger cation-anion interaction.

3D Printable Ceramic–Polymer Electrolytes for Flexible High‐Performance Li‐Ion Batteries with Enhanced Thermal Stability

“…This dual‐solvent system yielded high porosity after drying owing to phase separation into a solid‐like polymer rich phase and a liquid‐like polymer lean phase due to the higher boiling point of the nonsolvent, glycerol. Phase inversion has been used to achieve highly porous battery membranes, however, the resulting pore structure typically exhibits a large cellular‐ or finger‐like morphology that is not ideal for high rate performance or safety because it does not inhibit dendritic lithium growth. To overcome this issue, a high loading (70 wt%) of Al 2 O 3 nanoparticles (40–50 nm) was incorporated into a PVDF matrix to help reduce pore size and shrinkage as well as aid in lithium dendrite suppression, thermal stability, and electrolyte wetting.…”

Direct Partial Oxidation of Methane Catalyzed by an In Situ Generated Active Au(III) Complex at Low Temperature in Ionic Liquids

“…The higher solubility of CH 4 in the IL-containing [NTf 2 ] − anion was ascribed to the weak cation−anion interaction of the ILs, making CH 4 easy to insert into the cation−anion network of IL. 43 The effect of anions in IL compositions on the solubility of larger organic molecules such as thiophene has been well demonstrated. 51,52 In Chan's work, low CH 4 solubility was attributed as a limiting factor for CH 4 conversion in H 2 O and organic solvents.…”

“…However, few works reported ILs as the main solvent in catalyzed CH 4 partial oxidation, except for studies on the effects of ILs composed of Cl – , BF 4 – , Br – , CF 3 COO – , and HSO 4 – anions as additives to the concentrated sulfuric acid/Pt II system, CF 3 COOH/Pd II system, − or CF 3 COOH/Ru­(Pd)-Cu system, where the ILs were used to partially substitute the acid media to improve the water tolerance and alleviate the strong corrosion. In our previous work, CH 4 solubility in a variety of ILs were systematically studied. ILs, in general, have much higher CH 4 solubility than aqueous and organic solvents, especially for ILs containing C-F anions that were found to exhibit the highest stability and CH 4 solubility among the ILs. − …”

“…In our previous work, CH 4 solubility in a variety of ILs were systematically studied. ILs, in general, have much higher CH 4 solubility than aqueous and organic solvents, especially for ILs containing C-F anions that were found to exhibit the highest stability and CH 4 solubility among the ILs. − …”

Activation of Passive Nanofillers in Composite Polymer Electrolyte for Higher Performance Lithium‐Ion Batteries

“…Meanwhile, Peng et al investigated that by electrospinning the thermoplastic polyurethane/PVDF‐HFP, the ionic conductivity of the GPE can reach as high as 6.62 mS cm −1 . Although GPE normally possesses a lower ionic conductivity of around 10 −3 S cm −1 at room temperature compared to 10 −2 S cm −1 for liquid electrolytes, gel polymers have improved the safety and form factor . Incorporation of ceramic fillers into the polymer matrices improved the ionic conductivity by reducing the crystallinity and hence the glass transition temperature of the polymer.…”