Preparation of Carbon Molecular Sieves by Chemical Vapor Infiltration of Lignin Based Microporous Carbons

In a previous work we studied the influence of heat treatment on the molecular sieve properties of activated carbons prepared by chemical activation of lignin [1]. The thermal treatment modified the porous structure of the activated carbons, giving rise to solids that separate C6H6 from C6H12, CO2 from CH4 and O2 from N2 with a relative high selectivity. However, the heat treatment drastically reduced the adsorption capacity of these carbons. The access to the micropores of the activated carbons can be modified by deposition of pyrolytic carbon on the micropore entrance to generate constrictions similar in size to some adsorbing species, allowing their selective adsorption [2-6]. In the present work, the preparation of carbon molecular sieves (CMSs) by deposition of pyrolytic carbon on lignin-based microporous chars has been studied.