Preparation and Characterization of Molecular Sieving Carbon by Methane and Benzene Cracking over Activated Carbon Spheres

Abstract

Molecular sieving carbon (MSC) for separating <TEX>$O_2-N_2$</TEX> and <TEX>$CO_2-CH_4$</TEX> has been prepared through chemical vapor deposition (CVD) of methane and benzene on activated carbon spheres (ACS) derived from polystyrene sulfonate beads. The validity of the material for assessment of molecular sieving behavior for <TEX>$O_2-N_2$</TEX> and <TEX>$CO_2-CH_4$</TEX> pair of gases was assessed by the kinetic adsorption of the corresponding gases at <TEX>$25^{\circ}C$</TEX>. It was observed that methane cracking on ACS lead to deposition of carbon mostly in whole length of pores rather than in pore entrance, resulting in a reduction in adsorption capacity. MSC showing good selectivity for <TEX>$CO_2-CH_4$</TEX> and <TEX>$O_2-N_2$</TEX> separation was obtained through benzene cracking on ACS with benzene entrantment of <TEX>$0.40{\times}10^{-4}\;g/ml$</TEX> at cracking temperature of <TEX>$725^{\circ}C$</TEX> for a period of 90 minutes resulting in a selectivity of 3.31:1.00 for <TEX>$O_2-N_2$</TEX> and 8.00:1.00 for <TEX>$CO_2-CH_4$</TEX> pair of gases respectively.