THE MECHANISM AND ENERGETICS OF NOBLE GAS UPTAKE IN COPPER TRIMESATE, HKUST-1
Zeric Hulvey, Keith V. Lawler, Zhiwei Qiao, David Fairen-Jimenez, Randall Snurr, Sergey V. Ushakov, Alexandra Navrotsky, and Paul M. Forster
A joint experimental and computational study of noble gas adsorption in the metal-organic framework (MOF) material HKUST-1 has been carried out. By using a standard gas adsorption analyzer fitted with a cryostat, isotherms have been measured for these gases at optimum temperatures for the determination of loading-dependent heat of adsorption data using the Clausius-Clayperon equation. A detailed analysis of the experimental data alongside complimentary grand canonical Monte Carlo (GCMC) simulations led to the conclusion that the strongest binding for noble gases occurs in and around the small tetrahedral pockets present and not at the accessible Cu(II) sites in the structure. Heats of adsorption were also measured directly by calorimetry, showing reasonable agreement with those calculated from the adsorption isotherms. We also present an analysis of the temperature-dependence of the experimental Ar heat of adsorption data that can be explained using statistical mechanics and supported using GCMC calculations.