We present molecular simulations to find the optimal conditions for the separation by adsorption of SF 6 from a gaseous mixture with N 2 , a mixture of key interest in electrical applications. The effect of pore size, pressure, and mixture compositions on the selective adsorption of SF 6 was investigated by using Grand Canonical Monte Carlo simulations with simple fluid models and a simplified model of MCM-41. Simulations performed with multisite fluid models confirm that general trends are predicted using simple models, including a maximum in SF 6 selectivity for pore diameters around 1.1 nm. Simulations were also performed using two atomistic models of zeolite-templated carbon (ZTC), FAU-ZTC, and EMT-ZTC, materials with average pore sizes close to 1.1 nm, obtaining high selectivities for both materials. Selectivities for FAU-ZTC are approximately four times higher than the best materials published for this mixture separation, opening excellent opportunities to use it for recovering SF 6 from SF 6 /N 2 mixtures.