PNNL

Abstract

Exceptionally stable ultra-microporous C-C bonded porous organic framework (IISERP-POF6, 7, 8) have been prepared using simple Friedel-Crafts reaction. These polymers exhibit permanent porosity with a BET surface area of 645-800 m2/g. Xe/Kr adsorptive separation has been carried out with these polymers and they display selective Xe capture (s(Xe/Kr)) = 6.7, 6.32, 6.33) at 298K and 1 bar pressure. Interestingly, these polymers also show remarkable Xe/N2 (s(Xe/N2)) = 200, 180, 160 at 298K and 1 bar) and Xe/CO2 selectivity (s(Xe/CO2)) = 5.63, 7.4, 5.62) for a 1:99 composition of Xe:N2/Xe:CO2. Selective removal of Xe at such low concentrations is extremely challenging; the observed selectivities are higher compared to those observed in porous carbons and MOFs. Breakthrough studies were performed using the composition relevant to nuclear off-gas mixture with the polymers and we find that the polymers hold Xe for a longer time in the column which illustrates the Xe/Kr separation performance under dynamic condition.