High-Density Carbon Adsorbents for Natural Gas Storage
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-Density Carbon Adsorbents for Natural Gas Storage O. V. Solovtsovaa, S. S. Chugaeva, I. E. Men’shchikova, A. L. Pulina, A. V. Shkolina, and A. A. Fomkina, * a
Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, Moscow, 119071 Russia *e-mail: [email protected] Received June 8, 2020; revised June 15, 2020; accepted June 19, 2020
Abstract—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. DOI: 10.1134/S1061933X20060162
INTRODUCTION The adsorption technology of natural gas storage [1–5] is considered as an alternative to compressed natural gas (CNG) and liquefied natural gas (LNG) technologies. Possessing a volume capacity comparable with CNG, systems for storing adsorbed natural gas (ANG) make it possible to reduce the storage pressure by several times, increase working safety due to the “bound” state of methane in the field of adsorption forces of micropores, and improve the energy efficiency of the storage systems [6–8]. The following normative parameters established by the U. S. Department of Energy’s Vehicle Technologies are currently used as the reference requirements for the specific volume capacity of ANG storage systems: 260 m3 (NTP1)/m3 at a pressure of 3.5 MPa and a temperature of 298 K [9]. Active carbons possessing a high adsorption energy and a large micropore volume are promising adsorbents for the accumulation of natural gas (methane). The technology of active carbons is highly variable, thereby making it possible to synthesize highly active microporous carbon structures with different porosity parameters [10, 11]. Such materials are, as a rule, obtained as granules or powders. At the same time, as has been shown in [1], the most efficient approaches 1 NTP
denotes normal tempe
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