Density functional theory calculations have been combined with forcefield-based grand canonical Monte Carlo simulations to explore the adsorption of CO2, N-2, CH4 and H-2 on the small one-dimensional channel MIL-102, a naphthalene tetracarboxylate-based metal-organic framework (MOF) built up from a connection of trimers of trivalent iron. A detailed analysis is provided on the preferential arrangement of the confined adsorbates as well as the energetics of the host/guest interactions. The co-adsorption properties of this solid for the elimination of CO2 from hydrogen, natural and flue gases are then revealed. The so-predicted performances are further compared with those reported so far for a diverse series of MOFs.