Simulation of Dynamic Pressure-Swing Gas Sorption in Polymers

Abstract

A transport model was developed to simulate a dynamic pressure-swing sorption process that separates binary gas mixtures using a packed bed of non-porous spherical polymer particles. The model was solved numerically using eigenfunction expansion, and its accuracy verified by the analytical solution for mass uptake from a finite volume. Results show the process has a strong dependence on gas solubility. The magnitudes and differences in gas diffusivities have the greatest effect on determining an optimal particle radius, time to attain steady-state operation, and overall cycle time. Sorption and transport parameters for three different polyimides and one copolyimide were used to determine the degree of separation for CO2/CH4 and O2/N2 binary gas mixtures. The separation results for this process compare favorably to those for membrane separation using the same polymer, and significantly improved performance when a second stage is added to the pressure-swing process.