Characterization of zeolite membranes by temperature programmed permeationand step desorption

A temperature programmed permeation (TPP) system was employed to measure th e single gas permeances of H-2, N-2, CO2, methane, ethane, propane and n-bu tane through MFI membranes prepared on tubular alumina and stainless steel supports. The same system was used to measure the CO2/N-2 Separation select ivity using mixed feeds. The results obtained by TPP were in good agreement with permeation data gathered by on-line gas chromatography at fixed tempe ratures. However, the amount of information that could be obtained from TPP experiments in a comparable experimental time was much larger. Step desorp tion (SID) experiments were also carried out in which the response of the m embrane to a step change in the feed side concentration was continuously an alyzed. The permeation-temperature and permeation-time data gathered in the TPP and SD experiments with model compounds and mixtures provided valuable information on the permeation regimes, the adsorption processes taking pla ce and the overall quality of the membranes. (C) 2002 Elsevier Science B.V. All rights reserved.