Carbon molecular sieve membranes for selective CO₂ separation at elevated temperatures and pressures

The use of Carbon Molecular Sieve Membranes (CMSM) for selective CO2 separation from post-combustion CO2-rich streams from steel plant was experimentally evaluated and reported in this paper. Efficient CMSMs were developed for such application and their promising potentials in operating at elevated temperatures and pressures were experimentally demonstrated. The best performance in terms of flux as well as perm-selectivity, above the Robeson upper bound, was obtained using a CMSM developed with ethylenediamine in the dip-coating stage of the fabrication. In fact, adding ethylenediamine was proven to be particularly important in narrowing down the pore size distribution to ultra-micropore and establishing effective CO2 adsorption site over the membrane surface and the pores wall. It was shown that using a tailored CMSM with a precursor synthesized by co-polymerization of ethylenediamine with Novolac can improve the CO2/N2 ideal perm-selectivity from 33 to 97 at operational conditions of 200 °C and 20 bar.