Molecular simulation of methane adsorption in aluminophosphate molecular sieve AlPO4-11

Grand canonical Monte Carlo (GCMC) technique is employed to simulate the adsorption of methane in aluminophosphate AlPO4-11 molecular sieve. Adsorption isotherms over the temperature range of 296-673 K are simulated and compared with the experimental data. Two steps occur in these isotherms, which represent different adsorbed phases. The minimum average total potential is existed in the whole adsorption process, which corresponds to the most stable state of the adsorption system and to the adsorbed phase with four methane molecules per unit cell. Methane molecules predominantly occupy the 10-member ring channels of AlPO4-11. The initial heat of adsorption for methane estimated by Henry constants is −20.5 kJ/mol, which is in agreement with experimental data.