Rational design of nanoporous materials requires knowledge of adsorption isotherms and how they relate to structural features of the material. A method for the ab initio prediction of adsorption isotherms is presented which relies on a multi-site Langmuir model and the calculation of equilibrium constants for individual sites by quantum chemistry and molecular statistics [1]. We apply a quantum chemical multilevel method (Hybrid MP2:PBE+D+CCSD(T)) which is shown to yield adsorption energies with chemical accuracy (4 kJ/mol) [2]. This way, information is obtained on the contribution of each type site as well as on adsorbate-adsorbate interactions which are included using the Bragg-Williams model [1]. Specifically, storage of the energy-carrying molecules methane and hydrogen in metal-organic frameworks (MOF) is considered. For the ab initio prediction of adsorption isotherms of (binary) gas mixtures in metal-organic frameworks with regard to the separation of carbon dioxide from gas mixtures with methane or water Grand Canonical Monte Carlo simulations are made for a lattice of gas adsorption sites. The interaction energies between molecules at different sites are calculated by quantum chemical ab initio methods. [1] K. Sillar, J. Sauer, J. Am. Chem. Soc. 134 (2012) 18354. [2] A.D. Boese, J. Sauer, Phys. Chem. Chem. Phys. 15 (2013) 16481.

Ab initio simulation of adsorption isotherms for gases and gas mixtures in porous media

249th National Meeting (2015)

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