New Insights into Gas Uptake in Copper Trimesate

Zeric Hulvey (University Nevada)

Copper trimesate, also known as HKUST-1, was one of the first stable, highly porous metal-organic frameworks to be discovered. It has therefore been the subject of a number of investigations into gas storage and separations. We report a joint experimental and computational study of noble gas adsorption in HKUST-1 that sheds additional light into its uptake behavior. By using a standard gas adsorption analyzer fitted with a cryostat, high quality isotherms have been obtained for Ne, Ar, Kr, and Xe at temperatures not previously measured, and loading-dependent heat of adsorption curves have been obtained by applying the Clausius-Clayperon equation to these isotherms. This data indicates that the strongest binding for noble gases occurs in and around small tetrahedral pockets within the larger overall pore structure, and that little or no binding enhancement occurs with the presence of open copper sites in the structure. Lack of interaction with the metal sites has been further supported by good correlation of the experimental data to grand canonical Monte Carlo simulations which ignore any contribution from metal-sorbent electrostatic interactions. In contrast, our experimental heat of adsorption data for N2 and H2 clearly show the effect metal sites have on the adsorption of these molecular gases, corroborating past crystallographic data in the case of H2. Initial results which indicate a temperature dependence of heats of adsorption values have also been carried out in the case of Ar.

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