Sorption of Methane, Nitrogen, Oxygen, and Argon in ZSM-5 with different SiO 2 /Al 2 O 3 Ratios: Grand Canonical Monte Carlo Simulation and Volumetric Measurements

Sorption of CH 4, N 2, O 2, and Ar in ZSM-5 with different SiO 2 /Al 2 O 3 ratios was studied by volumetric measurements and grand canonical Monte Carlo simulation. Sorption capacity for all the gases studied was observed to decrease with an increase in the SiO 2 /Al 2 O 3 ratio of ZSM-5. The sorption selectivity of CH 4 over N 2 increases, whereas sorption selectivities of N 2 over O 2 and Ar decrease with an increase in the SiO 2 /Al 2 O 3 ratio of ZSM-5. ZSM-5 with SiO 2 /Al 2 O 3 of 900 showed higher selectivity for CH 4 over N 2, whereas the SiO 2 /Al 2 O 3 ratio of 25 showed higher N 2 selectivity over O 2 and Ar. The heats of adsorption for CH 4 and N 2 decrease and that for O 2 and Ar remain unaffected with an increase in SiO 2 /Al 2 O 3 ratio of ZSM-5. The values of Henry’s constant were also calculated for CH 4, N 2, O 2, and Ar for adsorption in ZSM-5 having varied SiO 2 /Al 2 O 3 ratio. The experimental results were compared with theoretically calculated data using grand canonical Monte Carlo (GCMC) simulation. Simulation studies expectedly showed the proximity of N 2 molecules to the sites occupied by extraframework sodium cations.