Simulation of the Mechanism of Gas Sorption in a Metal–Organic Framework with Open Metal Sites: Molecular Hydrogen in PCN-61
AuthorsForrest, Katherine A.
Belof, Jonathan L.
Stern, Abraham C.
Zaworotko, Michael J.
KAUST Grant NumberFIC/2010/06
MetadataShow full item record
AbstractGrand canonical Monte Carlo (GCMC) simulations were performed to investigate hydrogen sorption in an rht-type metal-organic framework (MOF), PCN-61. The MOF was shown to have a large hydrogen uptake, and this was studied using three different hydrogen potentials, effective for bulk hydrogen, but of varying sophistication: a model that includes only repulsion/dispersion parameters, one augmented with charge-quadrupole interactions, and one supplemented with many-body polarization interactions. Calculated hydrogen uptake isotherms and isosteric heats of adsorption, Q st, were in quantitative agreement with experiment only for the model with explicit polarization. This success in reproducing empirical measurements suggests that modeling MOFs that have open metal sites is feasible, though it is often not considered to be well described via a classical potential function; here it is shown that such systems may be accurately described by explicitly including polarization effects in an otherwise traditional empirical potential. Decomposition of energy terms for the models revealed deviations between the electrostatic and polarizable results that are unexpected due to just the augmentation of the potential surface by the addition of induction. Charge-quadrupole and induction energetics were shown to have a synergistic interaction, with inclusion of the latter resulting in a significant increase in the former. Induction interactions strongly influence the structure of the sorbed hydrogen compared to the models lacking polarizability; sorbed hydrogen is a dipolar dense fluid in the MOF. This study demonstrates that many-body polarization makes a critical contribution to gas sorption structure and must be accounted for in modeling MOFs with polar interaction sites. © 2012 American Chemical Society.
CitationForrest KA, Pham T, McLaughlin K, Belof JL, Stern AC, et al. (2012) Simulation of the Mechanism of Gas Sorption in a Metal–Organic Framework with Open Metal Sites: Molecular Hydrogen in PCN-61. The Journal of Physical Chemistry C 116: 15538–15549. Available: http://dx.doi.org/10.1021/jp306084t.
SponsorsThe authors would like to acknowledge the use of the services provided by Research Computing at the University of South Florida, including the NSF-funded computational resources (under Grant No. CHE-0722887). Computations were performed under a XSEDE Grant (No. MCA08 X 021) to B.S. This publication is also based on work supported by Award No. FIC/2010/06, made by the King Abdullah University of Science and Technology (KAUST). The authors also thank the Space Foundation (Basic and Applied Research) for partial support.
PublisherAmerican Chemical Society (ACS)