Thin Ionic Liquid Membranes Based on Inorganic Supports with Different Pore Sizes

Nanoporous TiO2 and SiO2-ZrO2 membranes with controlled pore sizes were prepared by sol gel processing and combined with a high CO2 solubility ionic liquid, 1-ethyl-3-methylimidazolium acetate ([emim][Ac]), by hand-coating the ionic liquid onto the membrane surface, and then by a spray-coating procedure. The CO2 permeation through SILMs based on a support with 20 nm pores (SILM-20), P-CO2 = 2.28 +/- 0.16 x 10(-8) mol/(m(2).s.Pa), was 62% higher than that permeance obtained for SILMs with 1 nm pore sizes (SILM-1). Besides, the activation energy for permeation increased for membranes with smaller pore sizes, which suggested that the properties of the ionic liquid were influenced by the interaction with the membrane pore surface. The membranes prepared by spray coating revealed a CO2 permeance as high as P-CO2 = 4.31 +/- 0.13 x 10(-8) mol/(m(2).s.Pa), with an ideal CO2/N-2 selectivity of alpha(CO2/N-2) = 31.18 +/- 1.34, which outperformed the current state-of-the-art materials for CO2/N-2 separation.