High performing CMS adsorbent for O2 / N2 separation

Abstract

The synthesis of a low particle size carbon molecular sieve (CMS) adsorbent was optimized for the O2/N2 separation. The best performing CMS displayed an O2/N2 adsorption kinetic selectivity of 123 and an inverse of apparent diffusion time constant of ca. 9 × 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 °C followed by milling and stabilization steps. The sample structure, morphology and performance were further examined by scanning electron microscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy, CO2 adsorption and adsorption capacity and kinetics of O2, N2, Ar and SF6 at 25 °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 O2/N2 separation performance.