Carbon molecular sieve membrane performance tuning by dual temperature secondary oxygen doping (DTSOD)

Carbon molecular sieves (CMS) can be formed into higher performance membranes for gas separation with high selectivities without sacrificing productivity by tuning the pyrolysis temperature and atmosphere. The presence of trace amount of oxygen in pyrolysis atmospheres allows tuning of the separation performance of CMS membranes. Despite these advantages, current CMS membranes would benefit from simultaneous higher productivities and selectivities. The present report introduces a new aspect to the oxygen doping method, where higher temperature and a trace amount of oxygen are used (with balanced argon) in a secondary step after pyrolysis (Dual Temperature Secondary Oxygen Doping, DTSOD) for enhancing the separation performance of CMS membranes for the O2/N2 gas pair while maintaining the high membrane permeance.