Porous Solids Impregnated with Task-Specific Ionic Liquids as Composite Sorbents

Abstract

This work examines six task-specific ionic liquids (TSILs), comprised of the taurinate anion paired with five tetraalkylammonium cations (where alkyl = methyl, ethyl, propyl, butyl, and hexyl) and a tetrabutylphosphonium cation, impregnated in ordered mesoporous silica, SBA-15. The composites showed significantly increased CO 2 uptakes relative to the parent SBA-15 materials. The surface area of these materials varies from approximately 5 to 1000 m 2 /g depending on the amount of IL loaded into the silica pores. The presence of n-hexyl side chains on the TSIL significantly reduces water loading, indicating that judicious IL selection may provide a means of controlling water uptake. After exposure to water vapor, three of the six cation-taurinate composites displayed an increase in CO 2 capacity. X-ray diffraction data of the composite of tetramethylammonium taurinate and SBA-15 shows that the ionic liquid is crystalline inside the pores of the silica. Isotherms are measured at several different temperatures and the results show that storage at ambient humidity significantly impacts the capacity of these materials. By comparison, the TSILs supported on an amorphous porous support, BPL activated carbon, showed no increase in CO 2 adsorption capacity. The results provide physical insight into the synthesis, structure, porosity, and sorption capacity of composites of adsorbents and ionic liquids that need to be considered prior to application.

Surface confinement induces the formation of solid-like insulating ionic liquid nanostructures

“…This is the case of electrodes made of i.e. nanoporous carbon (electrolitic supercapacitors [86][87], or silica or other oxides (for Gratzel cells, 88 gas-capture [89][90] , and catalytic [91][92] devices). The behavior of nano-confined ILs in porous matrices and nanostructures was recently reviewed.…”

Solid‐State Poly(ionic liquid) Gels for Simultaneous CO2 Adsorption and Electrochemical Reduction

“…Recently, ionic liquids (ILs) have been highlighted as promising materials for their capacity to selectively absorb 1 to 2 mg g −1 CO 2 at 1 bar . ILs exhibit high thermal and chemical stability, and can be easily incorporated into solid substrates such as porous silica to develop solid adsorbents with improved performance due to their higher surface area . However, these systems can only operate at low pressures in order to prevent IL loss during the recovery and separation process .…”

“…[10][11][12][13] ILs exhibit high thermal and chemical stability, [14][15][16][17] and can be easily incorporated into solid substrates such as porous silica to develops olid adsorbents with improved performance due to their higher surface area. [18][19][20][21] However, these systems can only operatea tl ow pressures in order to prevent IL loss during the recovery and separationprocess. [22] Poly(ionic liquids) (PILs), polymers derived from monomers basedo nI Ls,h ave also been investigated for CO 2 capturing.…”

Recent progress of task‐specific ionic liquids in chiral resolution and extraction of biological samples and metal ions

“…The method has broadened the utilization of ILs. Given that, the series of functional ILs were so called task-specific ionic liquids (TSILs) [27][28][29][30][31]. Nowadays, TSILs have exhibited their advantages and obtained much interest.…”