(152ah) Methane Absorption Capacities of Selected Organic Solvents for Turquoise Hydrogen Purification

Hydrogen is gaining attention as a new energy source for carbon neutrality. In addition to gray hydrogen, which is produced using traditional methods, blue hydrogen is produced by combining carbon capture, utilization, and storage (CCUS) technologies with gray hydrogen production, and green hydrogen is produced using renewable energy and water electrolysis. Turquoise hydrogen, similar to gray hydrogen produced by steam methane reforming, utilizes methane as a raw material and directly decomposes it into hydrogen and solid carbon using a high-temperature liquid metal as a catalyst and heat supply medium. Although turquoise hydrogen does not emit carbon dioxide as a byproduct in the hydrogen production process, the conversion rate of the raw material methane is hard to reach 100 %, necessitating the development of a technology to purify hydrogen by separating unconverted methane. In this study, we aimed to capture methane using organic solvents instead of the conventional pressure-swing adsorption (PSA) method. The organic solvents used in the experiment included traditional solvents such as polyethylene glycol, polar solvents, and ionic liquids. An automatic pressure control valve was installed between the reactor with the absorption solution and the gas cylinder to measure the solubility of methane and hydrogen, respectively, at room temperature under different pressures. The CH₄/H₂ selectivity of each solvent was calculated using the solubility of methane and hydrogen. The appropriate methane absorption solvent was selected based on the total methane absorption capacity and CH₄/H₂ selectivity. In addition, we diluted the solvent with water and measured its performance using the identical method. In the future, we will develop an CH₄ absorption process using the selected methane absorption solvent.