Hydrogen purification from underground storage via pressurized adsorption: Impact of adsorbent properties and operating parameters on methane separation

This study compared methane adsorption/desorption for hydrogen purification over a pressure range of 1–60 bar at room temperature. The main aim of this work was comparing methane adsorption performance of two commercial activated carbons (GAC and CAC) with different porous properties. GAC, with lower mesoporosity (24 %) and a surface area of 896 m 2 /g, demonstrated superior methane capacity and longer breakthrough times at high pressures and low CH 4 concentrations. Conversely, CAC, with higher mesoporosity, exhibited faster adsorption kinetics, especially at lower pressures and higher CH 4 concentrations. The Gompertz model best described dynamic adsorption, while the Bohart-Adams capacity was 0.44 kmol/m 3 for CAC and 0.63 kmol/m 3 for GAC at 60 bar. Langmuir and BET models showed a maximum monolayer capacity of 4 mmol/g for GAC, with an isosteric heat of 15.48 kJ/mol from the Dubinin-Radushkevich model. Optimal desorption used a H 2 purge-to-feed ratio of 0.16 and 4 bara pressure. • Increasing CH 4 adsorption capacity with higher microporosity at high adsorption pressure and low feed CH 4 concentration. • Improving CH 4 adsorption kinetics with higher mesoporosity at low adsorption pressure and high feed CH 4 concentration. • Bohart-Adams capacity: 0.44 & 0.63 kmol/m 3 for cylindrical & granular ACs (P Ads = 60 bar and 2 mol % CH 4 in feed). • Gompertz model fits asymmetric breakthrough curves better than logistic models. • Optimal desorption at H 2 purge to feed ratio of 0.16 and desorption pressure of 4 bara.