(49e) Adsorption of Small Molecules in Large-Pore Metal-Organic Frameworks

Porous metal-organic frameworks (MOFs) are quickly becoming established as a new class of porous materials with the potential to have a major impact on applications in gas storage, adsorption separations, and catalysis. Information on host-guest interactions at low pressure, the effect of uncoordinated metal sites, pore structure and volume, chemical functionality, and surface area is crucial to elevate MOFs to an applied level. Adsorption studies in MOFs have increased in recent years, but full structure-property relations have yet to be developed. This work reports the first adsorption data for a large-pore zinc MOF synthesized from the ligand 1,3,5-tris(4-carboxyphenyl) benzene (BTB). This material has a pore diameter of 3.2 nm and pore volume of 2.14 cubic centimeters per gram. Adsorption experiments and simulations were conducted for carbon dioxide, methane, nitrogen, and oxygen at various temperatures. Results are compared with adsorption results for other large pore MOFs. The character of each isotherm will be discussed in terms of the size, critical temperature, and vapor pressure of the adsorbate molecule. These results will be discussed within the broader context of materials design for adsorption separations.