MECHANISMS OF ADSORPTION OF CO2 IN THE MICROPORES OF ACTIVATED ANTHRACITE

The combined use of n-nonane preadsorption and CO2 adsorption at 273 K allows interpretation of the mechanism of adsorption of CO2 in narrow micropores of a series of CO2-activated carbons prepared from an anthracite. The mechanism depends on the shape and size of the pores. In narrow micropores of molecular dimensions (1 sigma), CO2 is probably adsorbed by micropore filling - as proposed for the adsorption of N-2 at 77 K - which is associated with curved CO2 isotherms at 273 K. With increasing degree of activation, the microporosity widens and the adsorption of CO2 in narrow micropores of supramolecular dimensions (>2 sigma) probably occurs by surface coverage, which is associated with rectilinear isotherms.