ADSORBED NATURAL-GAS STORAGE WITH ACTIVATED CARBONS MADE FROM ILLINOIS COALS AND SCRAP TIRES

Activated carbons for natural gas storage were produced from Illinois bituminous coals (IBC-102 and IBC-106) and scrap tires by physical act ivation with steam or CO2 and by chemical activation with KOH, H3PO4, or ZnCl2. The products were characterized for N-2-BET area, micropore volume, bulk density, pore size distribution, and volumetric methane s torage capacity (V-m/V-s). V-m/V-s values for Illinois coal-derived ca rbons ranged from 54 to 83 cm(3)/cm(3), which are 35-55% of a target v alue of 150 cm(3)/cm(3). Both granular and pelletized carbons made wit h preoxidized Illinois coal gave higher micropore volumes and larger V -m/V-s values than those made without preoxidation. This confirmed tha t preoxidation is a desirable step in the production of carbons from c aking materials. Pelletization of preoxidized IBC-106 coal, followed b y steam activation, resulted in the highest V-m/V-s value. With roughl y the same micropore volume, pelletization alone increased V-m/V-s of coal carbon by 10%. Tire-derived carbons bad V-m/V-s values ranging fr om 44 to 53 cm(3)/cm(3), lower than those of coal carbons due to their lower bulk densities. Pelletization of the tire carbons increased bul k density up to 160%. However, this increase was offset by a decrease in micropore volume of the pelletized materials, presumably due to the pellet binder. As a result, V-m/V-s values were about the same for gr anular and pelletized tire carbons. Compared with coal carbons, tire c arbons had a higher percentage of mesopores and macropores.