Gas Adsorption Study on Mesoporous Metal-Organic Framework UMCM-1

A mesoporous metal-organic framework (MOF) material, UMCM-1, has been synthesized and characterized using N-2 adsorption, powder X-ray diffraction scanning electron microscopy, and Fourier transform infrared techniques A detailed experimental study has been made of the adsorption of pure methane, hydrogen, carbon dioxide. oxygen. and nitrogen at various temperatures (298-338 K) and pressures (up to 25 bar). Multitemperature isotherms were modeled using the Dubmin - Astakhov equation to obtain useful thermodynamic properties including adsorption potential characteristic curves and isomeric heats of adsorption Results are compared with mesoporous carbons and silicas. Large-pore materials are shown to exhibit relatively high heats of adsorption for CO2 when open metal sites ale present This phenomenon is not observed for methane, which indicates the importance of the CO2 quadrupole in influencing binding strength Adsorption results for N-2 and O-2 show that selectivities in MOFs can be manipulated by the presence of absence of open metal sites UMCM-1 and MOF-177 show a slight preference for O-2 over N-2, However, open metal site MOFs such as Cu-BTC show the opposite adsorption preference, which is similar to zeolite selectivities. This experimental study reveals interesting adsorption information about a novel mesoporous MOF within the context of other MOFs and traditional mesoporous adsorbents These results can be used to advance the development of structure-property relationships for metal-organic frameworks