Hydrogen\nand Carbon Dioxide Kinetic Adsorption and\nDiffusion Behavior into Organic-Rich Shale: Implications of Mineralogy\nand Organic Content

Geological storage of hydrogen (GSH) is a pivotal technology\nfor\nadvancing an industrial-scale hydrogen economy. Shale formations,\nknown for their impermeable sealing and abundance, offer promising\npotential for secure GSH applications. However, the complex mineralogy\nand organic content of shale necessitate a detailed investigation.\nThis study examines the potential of organic-rich shale samples from\nJordanian oil source rocks for hydrogen (H<sub>2</sub>) storage and\ncarbon dioxide (CO<sub>2</sub>) sequestration. Adsorption kinetics\nwere measured at two different temperatures (303 and 333 K) and pressures\n(15 and 45 bar) using a volumetric experimental approach. Common mathematical\nmodels were applied to evaluate the adsorption data and calculate\nthe diffusion coefficients. The results indicate that H<sub>2</sub> adsorption on shale surfaces occurs at significantly lower rates\nthan CO<sub>2</sub>, with H<sub>2</sub> being adsorbed approximately\n2–7 times less as pressure increases from 0.1 to 68 bar. Both\ngases show increased adsorption with rising pressure and decreased\nadsorption at higher temperatures. The superior adsorption capacity\nof CO<sub>2</sub> highlights its potential as a cushion gas, facilitating\nthe preferential in situ separation of H<sub>2</sub> during extraction\nprocesses. This study also uses two distinct shale samples to explore\nthe impact of varying total organic carbon (TOC) and calcite contents\non gas adsorption capacity. The diffusion coefficients for H<sub>2</sub> were found to be approximately 10 times higher than those for CO<sub>2</sub>, offering critical insights into the dynamics of H<sub>2</sub> storage and retrieval in geological formations. The findings provide\ninsights into H<sub>2</sub> storage and retrieval in geological formations\nand enhance the feasibility of utilizing shale formations as reliable\nseals or storage media for H<sub>2</sub>.