Gas permeation models in the mixed matrix membranes

Abstract

Mixed matrix membranes are of great importance for gas separation. Commonly used fillers for MMMs are carbon molecular sieves and zeolites. Due to great technical importance of separation by MMM, estimation of permeability is needed. Purpose of this study is to select and modify a model for the permeation prediction of gas through mixed matrix membranes Permeation estimation models are discussed in this work. Original models represent two phases, polymer phase and an inorganic phase. By incorporating factors representing defects of mixed matrix membranes results can be made closer to the experimental data. Based upon analogy between parameters, models of thermal/electrical conductivities are applied to membrane permeation. By incorporating factors representing membrane defects results of permeation are made closer to the experimental values. Models are run by using MATLAB and results are compared. Hatta and Taya model(1) is selected for permeation prediction. Possible defects in MMMs might be voids formation, rigidification of polymer chains and the pore blockage. ���� is Chain immobilization factor also known as ratio of interface permeability to the matrix permeability and ���� is a factor representing ratio of interphase thickness to particle radius are introduced to the present model. Chain immobilization is a factor which causes a reduction in permeability. Models are validated by using experimental data of Matrimid-CMS, Ultem1000-CMS, BAPB-BPADDA (2,2 -bis(4- aminophenoxy)biphenyl and bisphenol A tetracarboxylic dianhydride)/ Zeolie 4A. Maxwell model, Lewis Nielson model, Baschirow model, Russell model, Hatta and Taya model and present model are evaluated for different MMMs and a comparison is done for different gases at different filler loadings. Average absolute relative error is calculated, present model shows the relative error in the range of 3.25%-7.80%. Results showed that the present model is in good agreement with the experimental.