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.

► High performance carbon molecular sieve (CMS) membrane preparation is presented. ► Performance of CMS fiber membranes is tuned by dual temperature treatment. ► Combining “O2-doping” with dual temperatures enables the improved performance. ► The approach is illustrated for the O2/N2 gas pair. ► Membranes with balanced O2/N2 selectivity and high oxygen permeance were achieved.