Molecular simulations were performed to evaluate the influence of CO2 in the deactivated volume of storage vessels used in the adsorbed natural gas (ANG) technology. We compare the performance of metal-organic framework Cu-BTC and a hypothetical carbon material. The adsorption of carbon dioxide in the discharge pressure and room temperature (1 atm, 25 ° C) impairs the efficiency of charge and discharge cycles of the natural gas. Data for the adsorbing mixture CH4/CO2 were obtained for the charge and discharge pressures. Methane /CO2 selectivity calculations were performed to compare the adsorbents Cu-BTC and the activated carbon. The metal-organic framework Cu-BTC presented similar CH4 loading to the hypothetical activated carbon. Although Cu-BTC presented a higher CO2 loading, this quantity is unable to effectively interfere with the charge/ discharge cycle efficiency. Considering that our activated carbon is a hypothetical material, we concluded that metal-organic framework Cu-BTC is a very promising adsorbent for ANG technology.