(149b) Revolutionary Ultrathin Carbon Molecular Sieve Hollow Fiber Membranes

Revolutionary ultrathin carbon
molecular sieve hollow fiber membranes

Chen Zhang, William J. Koros

Georgia Institute of Technology, Atlanta, Georgia U.S.A.

Carbon molecular sieves (CMSs) are membrane materials with
tailored microporosity offering attractive mechanical properties and
extraordinary permselectivities for many gas pairs. The extraordinary permselectivities
well exceed polymer upper bounds, which rely upon entropically-enabled
diffusion selectivities and synergistic sorption selectivities.¹
CMSs can be transformed into the preferred scalable hollow fiber geometry by
controlled pyrolysis of asymmetric polymer precursor hollow fibers. The porous
substrate of CMS fibers tends to densify during pyrolysis. In that case, the CMS
hollow fiber membrane completely or partially loses its asymmetry, thereby
producing thick separation layer (30-50 μm) with unattractive permeance.²

In this work, we present
formation of CMS hollow fiber membranes with ultrathin skin (separation) layers
for gas and vapor separations. By tuning the membrane structure and formation
process, we have created advanced CMS hollow fiber membranes with
excellently-preserved asymmetry and defect-free sub-micron skin layers. The
ultrathin CMS hollow fiber membranes show permeances that are an order of
magnitude higher than state-of-the-art CMS hollow fiber membranes for a given
precursor material³, while maintaining highly attractive separation
factors. Combining high scalability, high permeance and high selectivity, the
ultrathin CMS hollow fiber membranes offer an attractive and uniquely-flexible
platform for next-generation membrane-enabled fluid separations.

References

1            Koros,
W. J. & Zhang, C. Nat Mater 16, 289-297, (2017).

2            Xu,
L., Rungta, M. & Koros, W. J. J. Membr. Sci. 380, 138-147,
(2011).

3            Bhuwania,
N. et al. Carbon 76, 417-434, (2014).