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.