Diffusion of light gases in 6FDA/BPDA-DAM Carbon Molecular Sieve membranes by Pulsed Field Gradient NMR

Abstract

In this paper, we demonstrate the potential of pulsed field gradient (PFG) NMR spectroscopy to reveal detailed knowledge of self-diffusion of light gases and light gas mixtures in carbon molecular sieve membranes on small length scales. PFG NMR is used to investigate intra-membrane diffusion of carbon dioxide and methane for a broad range of temperatures and mean square displacements in a carbon molecular sieve membrane derived from a 6FDA/BPDA-DAM polyimide film. Diffusion is investigated with single component sorbates as well as with a carbon dioxide / methane mixture. Results obtained from these studies are compared and discussed.