The application of transient time-lag method for the diffusion coefficientestimation on zeolite composite membranes

Time-lag method is a very popular technique which has been developed and wi dely used for the measurement of diffusion coefficients on polymer membrane s. In this work we applied the transient time-lag method for the determinat ion and the modeling of a global diffusion coefficients for CO2 and CA thro ugh a composite MFI cylindrical membrane. The developed equations were used for the estimation of global apparent diffusion coefficients which include s the Knudsen like diffusion through intercrystalline holes and the intracr ystalline microporous diffusion. The diffusion coefficient was calculated f or a previous estimated membrane thickness. This last parameter was obtaine d from the modeling of steady state permeability at high temperature and fo r a non-adsorbing gas like helium. (C) 2001 Elsevier Science B.V. All right s reserved.