(609i) Adsorption-Induced Deformation of Nanoporous Carbons with Mixtures: A Hybrid MC/MD Approach

Adsorption-induced deformation of nanoporous carbons has many practical applications, from mixture separations to hydrocarbon storage, carbon sequestration, and natural gas recovery. However, most experimental and theoretical studies have focused on single-component adsorption, while practical applications often involve gas mixtures. This work represents the first systematic effort to simulate nanoporous carbon deformation during binary adsorption using 3-dimensional models [1] and a hybrid (MC) / molecular dynamics (MD) technique. As an example, we consider the displacement of methane by carbon dioxide in the microporous fractions of coals at geologically relevant conditions. [2] To replicate the complex range of surface areas, pore volumes, and pore size distributions present in nanoporous carbons, we generate 3-D structures using the MD annealing method. We simulate the adsorption-induced deformation of methane, carbon dioxide, and their binary mixtures by using successive MC/MD iterations (see Figure). In the first step, we equilibrate the adsorbate with the rigid structure using grand canonical MC simulations. In the next step, we allow the structure to deform anisotropically in response to the adsorbed molecules using isothermal-isobaric (NPT) MD simulations. We analyze the effects of structural properties, thermodynamic conditions, and gas compositions on the adsorbent deformation and its impact on adsorption capacity and selectivity.

This work is supported by the NSF CBET grant 1834339 and ExxonMobil.

[1] N.J. Corrente, E.L. Hinks, A. Kasera, R. Gough, P.I. Ravikovitch, A.V. Neimark, Modeling adsorption of simple fluids and hydrocarbons on nanoporous carbons, Carbon 197 (2022) 526-533.
[2] N.J. Corrente, K. Zarȩbska, A.V. Neimark, Deformation of Nanoporous Materials in the Process of Binary Adsorption: Methane Displacement by Carbon Dioxide from Coal, The Journal of Physical Chemistry C 125(38) (2021) 21310-21316.