Abstract
Ionic liquids have been used in membrane separation for more than a decade due to their physical and chemical properties, such as non–volatility, thermal stability and unique solubility. In this paper, we present a new concept in chemically stabilized IL membranes using a silylated IL as a precursor chemical. The membranes showed selective permeability toward organic vapors against H2 and CH4. Their permeation and separation mechanism, and microstructure were discussed by gas and vapor permeation tests, Attenuated Total Reflection–IR, N2 adsorption measurements, and nanopermporometry. These characterization revealed that the membranes depend on two permeation pathways, “only the dense ionic liquid regions” and “Si–O– network derived–micropores + dense ionic liquid regions”. The membranes contained about 1 nm–sized micropores, and the contributions of two permeation pathways to H2 permeation were successfully evaluated. In addition, ionic liquid–immobilized siloxane membranes with a different Si–O– network structure were developed, and their CH3OH permeation characteristics were discussed.
