CO₂ Capture by Novel Supported Ionic Liquid Phase Systems Consisting of Silica Nanoparticles Encapsulating Amine-Functionalized Ionic Liquids

Abstract

We report novel supported ionic liquid (IL) phase systems, described as “inverse” SILPs, consisting of micron size IL droplets within an envelope of silica nanoparticles. These novel IL-in-air powders, produced by an easily scalable phase inversion process, are stable up to 60 °C and 30 bar and are proposed as a means to confront the major drawbacks of conventional SILPs for gas separation. SILPs are usually formed by filling the channels of nanoporous materials with the IL phase. In case the core space of the pores remains open, such conventional SILPs exhibit lack of gas absorption specificity, while complete pore filling leads to diffusivity that is very low compared to that for corresponding bulk ILs; the latter drop is largely due to the high tortuosity of the pore network of the support. The inverse SILPs prepared in this work exhibited promising CO2/N2 separation performance that had reached the value of 20 at absorption equilibrium and enhanced CO2 absorption capacity of 1.5–3 mmol g–1 at 1 bar and 40 °C. Moreover, the CO2 absorption kinetics were very fast compared to conventional SILP systems and to simultaneous N2 absorption; the CO2/N2 selectivity at the short times of the transient stage of absorption had reached values in excess of 200.

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

“…58 Only a few works have examined supported task-specific ionic liquids as composite adsorbents. [59][60][61][62][63][64] Specifically, Zhang et al…”

High capacity CO2sorbents based on zinc-functionalized ionic liquid confined in morphologically diverse porous matrices

“…The difference (∆V = V p,lost -V EZT3 ) can be used to interpret the degree of pore inclusion. In the case of non-porous nano-SiO 2 (S12-0), we only found two reports of their use: 1) PEI-SiO 2 hybrid sorbents, 59 and 2) inverse-SILP sorbents, 39 probably due to the lack of porosity in this material. A positive value may indicate some degree of pore blocking resulting in some pores becoming unavailable for N 2 adsorption.…”

“…This is consistent with the results of the N 2 adsorption experiments where the mesopores were completely filled while the IL experienced molecular sieve effects with the micropores. 39 Sorption kinetics is an important parameter in evaluating the performance of CO 2 sorbent materials. Small angle neutron scattering (SANS) studies are currently being explored to provide unequivocal resolution on which of the two cases predominates, and how much volume is occluded if pore blocking occurred.…”

“…38 Complete filling of the nanopores was suggested to fully exploit the capacity of the IL in SILP materials, 39 but this is not suitable for highly viscous systems. organo-amines, ILs, amidines) plays a crucial role in the overall performance of the hybrid sorbents.…”

CO<sub>2</sub> Absorption Performance of “Dry Matter” Prepared with Amino Acid-Based Ionic Liquids

“…Since ionic liquids (ILs) have favorable properties such as negligible volatility and excellent thermal stability, they are free from some of the above drawbacks. A prominent example for the application of ILs for the CO 2 absorption has been reported by Romanos et al [11] who employed the "inverse supported ionic liquid phase materials" (inverse SILPs). SILP is a material in which ILs are supported or adsorbed on the surface of porous substrate.…”