Abstract—

A one-step notion of synthesis was developed to prepare microporous activated carbons from walnut shell by physical gas activation in a CO₂ 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 CO₂ 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 W₀ = 0.59 cm³/g, mesopore volume W_МЕ = 0.33 cm³/g, specific surface S_BET = 1490 m²/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.

中文翻译：

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由核桃壳制备的碳纳米孔吸附剂，用于低温存储系统中的液化天然气蒸气回收

摘要-

研究人员开发了一种合成概念，可通过在120、160和178 K下运行的低温甲烷累积系统在CO ₂气氛中通过物理气体活化从核桃壳中制备微孔活性炭。温度范围为240至950°C。发现对于在CO ₂气氛中吸附剂中的微孔发展而言，接近900°С的温度是最佳的。在这些条件下的活化可以使燃烧度达到70％，并形成用于吸附液化天然气（LNG）蒸气的最佳多孔结构。由此获得的吸附剂表现出高的微孔体积W ₀＝ 0.59cm ³ / g，中孔体积W¯¯ _МЕ =0.33厘米³ /克，比表面积小号_BET =1490米² / g，且为0.59纳米，这提供了一种高甲烷的吸附能力的微孔的半宽度。中孔的存在会由于毛细管冷凝而对吸附过程做出额外的贡献。对吸附剂的甲烷吸附能力的理论评估表明，在120、160和178 K的温度以及最高6 bar的压力下，平衡吸附的值分别为15、13.5和12 mmol / g。