Carbon Nanoporous Adsorbents Prepared from Walnut Shell for Liquefied Natural Gas Vapor Recovery in Cryogenic Storage Systems

• Published in: Protection of metals and physical chemistry of surfaces 2020-11, Vol.56 (6), p.1122-1133
• Main Authors: Men’shchikov, I. E., Fomkin, A. A., Romanov, Yu. A., Kiselev, M. R., Pulin, A. L., Chugaev, S. S., Shkolin, A. V.
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Corrosion and Coatings; Industrial Chemistry/Chemical Engineering; Inorganic Chemistry; Materials Science; Metallic Materials; Physicochemical Processes at the Interfaces; Tribology
• ISSN: 2070-2051; 2070-206X
• DOI: 10.1134/S2070205120050202

— A one-step notion of synthesis was developed to prepare microporous activated carbons from walnut shell by physical gas activation in a CO 2 atmosphere for a low-temperature methane accumulation system operating at 120, 160, and 178 K. The raw material was carbonized within a temperature range from 240 to 950°C. Temperatures close to 900°С were found to be optimal for the development of microporosity in the adsorbent in a CO 2 atmosphere. Activation under these conditions made it possible to achieve a burnoff degree up to 70% and form an optimal porous structure for adsorption accumulation of liquefied natural gas (LNG) vapors. The adsorbent thus obtained exhibits a high micropore volume W 0 = 0.59 cm 3 /g, mesopore volume W МЕ = 0.33 cm 3 /g, specific surface S BET = 1490 m 2 /g, and half-width of micropores of 0.59 nm, which provided a high methane adsorption capacity. The presence of mesopores can make additional contribution to the adsorption process due to capillary condensation. The theoretical assessment of the methane adsorption capacity of the adsorbent showed that at temperatures of 120, 160, and 178 K and pressures up to 6 bars, the values of equilibrium adsorption were 15, 13.5, and 12 mmol/g, respectively.