(293a) Molecular Modeling of the Adsorption of Small Molecules in Metal-Organic Frameworks

Metal-organic frameworks (MOFs) are a new class of nanoporous materials synthesized in a “building-block” approach by self-assembly of metal or metal-oxide vertices interconnected by rigid organic linker molecules. The rational synthesis approach opens up the possibility of incorporating a wide variety of functional groups into the materials, and these materials may lend themselves to new advances in adsorption separations, gas storage, and catalysis. Because of the predictability of the synthetic routes and the nearly infinite number of variations possible, molecular modeling is an attractive tool for screening new structures before they are synthesized. Modeling can also provide insight into the molecular-level details that lead to observed macroscopic properties.

We have used atomistic grand canonical Monte Carlo simulations to predict adsorption isotherms for hydrogen, nitrogen, carbon dioxide, methane, and their mixtures in several classes of MOFs to explore the possibilities for several important adsorption separations. Comparisons of predicted single-component isotherms and heats of adsorption will be made with experimental data from the literature. Predictions for mixtures will be used to make suggestions for possible separations applications.