As a high-silica hydrophobic material

zeolite ZSM-5 was used for the adsorption and recovery of low concentration coal-bed methane. Theoretical and experimental studies were conducted on adsorption equilibrium

adsorption kinetics and vacuum pressure swing adsorption (VPSA). Single and binary competitive adsorption equilibrium experimental data of CH4/N2 on zeolite ZSM-5 were measured by gravimetric method and breakthrough-curve method. The multi-site Langmuir model was used to fit the experimental data. Microporous diffusion coefficients were calculated based on the experimental data of diluted breakthrough curves and simulated results of an isothermic mathematical bi-disperse model without momentum loss. Competitive breakthrough curves of CH4 and N2 on zeolite ZSM-5 were predicted by fixed bed adsorption models with mass

momentum and energy transfer. Effects of CH4 concentration in feed

feed flow rate

feed time and purge/feed flow rate ratio on separation performances of ZSM-5 packed single column four-step VPSA process were investigated. It showed that ZSM-5 zeolite exhibited a relatively good selectivity for CH4 and the diffusion in micropores was the rate determining step for both CH4 and N2 adsorption. By the process of VPSA

CH4 purity can be concentrated from 20% to 31%～41% and the recovery can be up to 93%～98%.