Abstract
The CO2 emissions from major industries can cause serious global environment problems and their mitigation is urgently needed. The use of zeolite membranes is a very efficient way in order to capture CO2 from some flue gases. Zeolite membranes are porous crystalline materials with pores of a consistent size and these pores are generally of molecular size 0.3 to 1.3 nm, and enable high selectivity and reduced energy requirements in industrial separation applications. Further, zeolites are thermally stable and have known surface properties. Separation in zeolites is mainly based on dissimilarity of diffusivities, favored absorption between the components and/or molecular sieving effects.
The present work is aimed at developing a simulation model for the CO2 transport through a zeolite membrane and estimate the diffusion phenomenon through a very thin membrane of 150 nm in a Wicke-Kallenbach cell. This apparatus has been modeled with COMSOL Multiphysics software. The gas in the retentate gas chamber is CO2 and the inert gas is argon. The Maxwell-Stefan surface equations used in order to calculate the velocity gradients inside the zeolite membrane and in order to solve the velocity profile within the permeate and retentate gas chamber, the incompressible Navier-Stokes equations were solved. Finally, the mass balance equation for both gases was solved with the mass balance differential equations. Validation of the model has been obtained at low and high temperatures suggesting that higher the temperature the more beneficial the outcome. (C) 2014 Elsevier Ltd. All rights reserved.