MICROPOROUS ACTIVATED CARBONS FROM A BITUMINOUS COAL

A Spanish bituminous coal was used as raw material to prepare activate d carbons both by CO2 and by chemical activation. The activated carbon s were characterized by adsorption of N-2 at 77 K, CO2 at 273 K and be nzene and cyclohexane at 303 K, as well as by mercury porosimetry and helium density. The microporosity of the activated carbons was evaluat ed by the Dubinin-Astakhov equation applied to the adsorption isotherm s and the ct-plot method applied to the N-2 adsorption data. All activ ated carbons studied were essentially microporous. The sample obtained by chemical activation with phosphoric acid had the widest micropores . The micropore volumes of activated carbons with medium to high activ ation determined by N-2 and CO2 adsorption were quite similar, so both adsorbates measured the same type of micropores. Molecular sieve effe cts for benzene and cyclohexane were detected in activated carbons wit h low to medium activation. (C) 1996 Elsevier Science Ltd.