Separation of nitrogen from air by carbon molecular sieve membranes

In this work, the experimental properties of a carbon molecular sieve membrane made out of cellophane were used to model and simulate a membrane module for the production of nitrogen from air. The mass transport across the membrane has been related to its porous structure. The mathematical model developed accounts for counter- and co-current operation modes, pressure-dependent permeabilities and pressure drop along the membranes. A product stream of high pure nitrogen (>99.9%) was obtained from the retentate side, with recoveries up to 65%. It was considered different feed to permeate pressure ratios and different feed pressures. It was concluded that higher ratios and higher feed pressures favor the separation. Furthermore, the pressure drop along the membranes has a negative impact on the performance of the unit.