Sorption studies of CO2, CH4, N2, CO, O2 and Ar on nanoporous aluminum terephthalate [MIL-53(Al)]

Aluminum terephthalate, MIL-53(Al), metal–organic framework synthesized hydrothermally and purified by solvent extraction method was used as an adsorbent for gas adsorption studies. The synthesized MIL-53(Al) was characterized by powder X-Ray diffraction analysis, surface area measurement using N2 adsorption–desorption at 77 K, FTIR spectroscopy and thermo gravimetric analysis. Adsorption isotherms of CO2, CH4, CO, N2, O2 and Ar were measured at 288 and 303 K. The absolute adsorption capacity was found in the order CO2>CH4>CO>N2>Ar>O2. Henry’s constants, heat of adsorption in the low pressure region and adsorption selectivities for the adsorbate gases were calculated from their adsorption isotherms. The high selectivity and low heat of adsorption for CO2 suggests that MIL-53(Al) is a potential adsorbent material for the separation of CO2 from gas mixtures. The high selectivity for CH4 over O2 and its low heat of adsorption suggests that MIL-53(Al) could also be a compatible adsorbent for the separation of methane from methane–oxygen gas mixtures.