Two new metal-organic frameworks: Synthesis, characterization, gas adsorption and simulation

Two new Metal-organic frameworks, [Na1Ni3(mu(3)-OH)(mu(5)-BTC)(mu(6)-BTC)(H2O)(3)]center dot 4H(2)O (BTC = Benzene tricarboxylate ion) (1) and [Na1Co3(mu(3)-OH)(mu(5)-BTC)(mu(6)-BTC)(H2O)](3)center dot 4H(2)O (2) were synthesized under hydrothermal conditions and characterized by FT-IR, TGA, elemental analyses, single crystal and powder X-ray diffraction techniques. The porous structure of 1 and 2 were investigated by BET, crystal voids, topological analysis, gas adsorption and GCMC simulations. In the pressure range from 0.1 to 1.5 bar the adsorption selectivity of CO2 over CH4 at 273 K, 288 K and 298 K, is high in the activated MOFs. However, the adsorption selectivity reduces to 1.3 by increasing the pressure to 10 bar. GCMC simulations indicated probable interactions of CO2 around metal nodes and CH4 near the carboxylate groups. Experimental gas adsorption together with the GCMC simulation suggested 1 and 2 can be potential candidates for greenhouse gas capture or CO2/CH4 separation.