High performing CMS adsorbent for O-2/N-2 separation

Abstract

The synthesis of a low particle size carbon molecular sieve (CMS) adsorbent was optimized for the O-2/N-2 separation. The best performing CMS displayed an O-2/N-2 adsorption kinetic selectivity of 123 and an inverse of apparent diffusion time constant of ca. 9 x 10(-2)s(-1); these are the highest values reported for an oxygen chemisorption stabilized sample. The adsorbent was prepared from the carbonization of a cellulosic precursor at 1000 degrees C followed by milling and stabilization steps. The sample structure, morphology and performance were further examined by scanning electron microscopy, thennogravimetric analysis, Fourier transform infrared spectroscopy, CO2 adsorption and adsorption capacity and kinetics of O-2, N-2, Ar and SF6 at 25 degrees C. SEM micrographs showed very fine powder particles with stomas. CO2 adsorption isotherms revealed that the CMS adsorbent has a well-developed microporous structure. The obtained results were well above the ones reported on literature for similar conditions opening the door for the preparation of stable carbon molecular sieve adsorbents with extraordinary O-2/N-2 separation performance.