Solubility and selectivity behavior of methane and hydrogen in several solvents at 313.15 K

• Published in: Journal of molecular liquids Vol. 427; p. 127327
• Main Authors: Son, Juhee, Verma, Sweety, Kang, Jo Hong, Park, Hyun Sic, Song, Hojun, Bae, Youn-Sang
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.06.2025
• Subjects: Free volume; Intermolecular interaction; Non-polar solvents; Refractive index; Solubility; Solvent selectivity; Intermolecular interaction; Free volume; Solvent selectivity; Non-polar solvents; Refractive index; Solubility
• ISSN: 0167-7322
• DOI: 10.1016/j.molliq.2025.127327

[Display omitted] •The absorption process at ambient pressure for the CH4/H2 separation is evaluated due to the lack of existing data on the subject.•The solubility and selectivity of CH4 and H2 for the potential solvents are measured and compared.•The relationship between the solvent structure and solubility is discussed.•Cyclohexane exhibits the most optimal performance in terms of CH4 absorption and selectivity. The turquoise hydrogen process, which involves the decomposition of methane (CH4) into hydrogen (H2) and carbon black, necessitates the effective separation of unreacted methane from the produced gas to ensure high-purity hydrogen. This study investigates the efficacy of various solvents such as ethanol, n-hexane, oleic acid, ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate), cyclohexane, ethylene glycol, and 1,4-dioxane in the absorption of CH4 and H2 for purification. Absorption experiments were conducted using 50 mL of each pure solvent at 313.15 K, and the solubility of CH4 and H2 was analyzed on both molar and mass basis. Oleic acid exhibited the highest absorption capacity for both gases on a molar basis. In contrast, n-hexane and cyclohexane demonstrated the highest selectivity for CH4 over H2. The selectivity of CH4/H2 decreased with the higher partial pressure and smaller molecular size of H2, which makes it easier to occupy free volume in the solvent than CH4. Additionally, solvents containing polar atoms or groups, such as ethylene glycol and 1,4-dioxane with oxygen (O) or hydroxyl group (–OH), impeded CH4 absorption, decreasing the selectivity. This comprehensive analysis demonstrates the potential of these solvents in optimizing the hydrogen purification process and provides information for the development of more efficient separation techniques.