Methane upgrading on pelletised Maxsorb activated carbon by gas-phase simulated moving bed

Abstract

To study the separation of methane and nitrogen mixtures by gas-phase simulated moving bed (SMB), Maxsorb activated carbon was pelletised by extrusion with 10% binder. Both argon and carbon dioxide were used as potential desorbent gases. The effectiveness of the adsorbent was assessed by analysing the adsorption equilibrium data and conducting fixed-bed experiments to determine the single and multicomponent dynamic adsorption behaviour. Pure component N2, CH4, Ar, and CO2 isotherms were measured at three different temperatures, up to 2.5 bar, using a volumetric method. The results show that CO2 exhibits the highest affinity to the solid phase, followed by CH4, N2, and Ar. Single, binary, and ternary fixed-bed experiments were performed, allowing the validation of the proposed mathematical model. Two SMB cycles were designed to separate a CH4/N2 mixture using each desorbent gas. The respective separation regions were drawn. Both processes achieved a high purity level for the methane stream (above 99%) and exhibited high recovery (above 97%). The obtained results were crossed with the previously studied BPL material, and the Maxsorb adsorbent showed better performance overall.