Structural and textural control of high-pressure hydrogen adsorption on expandable and non-expandable clay minerals in geologic conditions

摘要

Both natural and anthropogenically-generated hydrogen gas occurs in sedimentary rocks and geotechnical barriers. Due to high-pressure conditions, a significant portion of H-2 can be physisorbed in available micropores of clay minerals, which have been proven to control the gas adsorption properties of rocks. This study investigates H-2 adsorption on clay minerals naturally occurring in rocks, by combining the high-pressure H-2 experiments with sample characterization analyzed using low-pressure adsorption of N-2 and CO2, and structural analysis using X-ray diffraction. We found that H-2 adsorption depends strongly on the mineral texture, which is not related directly to its structure. Most of H-2 is adsorbed in the micropores accessible to CO2. H-2 intercalates in the smectitic interlayers with a basal spacing larger than 10.8 angstrom. The density of adsorbed H-2 is about double that of free H-2 gas under given pressure and temperature, effectively increasing the gas storage capacity of rocks. (C) 2022 The Author(s). Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.