Kaolin-Based Hydrogen Adsorption: Impact of Surface Pretreatment

Hydrogen storage is one of the critical points in the widespread adoption of hydrogen. Kaolin shows strong potential, as it allows for greater adsorption of small molecules such as H 2, and its adsorption capacity can be increased by improving its surface properties through chemical pretreatment. For this purpose, kaolin was pre-treated with HCl to investigate the effect of varying temperature, duration, and acid concentration on clay structure and H 2 adsorption. With increased acidic and thermal conditions, the SiO 2 /Al 2 O 3 ratio increased, while the intensity of Al– O –H peaks in FT-IR results decreased. Kaolinite peaks became more pronounced with increasing acid concentration and had increased crystallinity, while SEM showed the rod/spiky fine flake structure. These changes affected the surface area and pore structure, thereby increasing its H 2 adsorption capacity (from 0.0844 mmol/g to 0.1691 mmol/g). Although increasing duration improved the structure, it reduced hydrogen adsorption by 8.3–16 %. Treated kaolin has a homogeneous structure for H 2 adsorption. • Treated kaolin have homogeneous structure with high surface area and micropore volume. • Thermochemical pretreatment affected crystallinity less negatively at higher durations. • Optimum H 2 adsorption is possible with a pretreatment of 110 °C and 2h • 1 M acidic solution was better to pretreat kaolin for H 2 adsorption.