Highly Facilitated Permeation and Oxygen Enrichment from Air through Polyvinylimidazole Membrane Ligated with Kinetically Oxygen Interacting Cobaltporphyrin

Abstract

A dense and tough membrane of cobalt tetraphenylporphyrin (CoTPP) and poly(1-vinylimidazole-co-octyl methacrylate) (OIm) is prepared on a porous support. The oxygen permeability coefficient and oxygen/nitrogen permselectivity reach 10 Barrer and >110, respectively, at a pressure difference between the feed and permeate side of 2 cmHg. The membrane with a diameter of 10 cm enriches oxygen from dried air to an oxygen concentration > 60% through a one-shot permeation process. The reversible but kinetically very active interaction with oxygen molecules of the CoTPP fixed in the OIm membrane is analyzed for the membrane under a high oxygen pressure or low temperature with spectroscopies including laser-flash photolysis: i.e. >920 cmHg for the half of the CoTPP interacted with oxygen and extremely rapid oxygen-releasing rate constant of approximately 106 s⁻¹, extrapolated at room temperature. The enhanced oxygen diffusivity is discussed for the facilitated oxygen permeation through the membrane.