High-Density Carbon Adsorbents for Natural Gas Storage

Physicochemical regularities are studied for the synthesis of molded active carbons based on coconut shells and peat, with a latex emulsion and a carboxymethyl cellulose (CMC) sodium salt solution being used as binding agents. The materials are obtained at compacting pressures of 25, 50, and 100 MPa. The specific surface areas of the composite samples obtained from peat and coconut shells are SBET ≈ 1320 and ≈1290 m2/g, respectively. The specific micropore volumes of the composites based on peat and coconut shells are W0 = 0.50 and 0.45 cm3/g, respectively. Latex-modified carbon samples have a higher bulk density than those molded with CMC. The molding of the active carbons is accompanied by partial degradation of their porous structure. The Dubinin theory of volume filling of micropores (TVFM) has been employed to calculate the values of adsorption and active specific capacity of the molded adsorbents with respect to methane at a temperature of 273 K and a pressure of up to 100 bar. The experimental and calculated data have shown that the active capacity of the new microporous carbon composite materials may be as large as 180 m3 (NTP)/m3, when the pressure drops from 100 to 1 bar. It has been concluded that it is reasonable to employ the TVFM for preliminary calculations of the parameters of adsorption systems used for natural gas storage.