Brandon William Swanson Bout

(Co-Advisors: Krista S. Walton and David S. Sholl)

will defend a doctoral thesis entitled,

Computational Investigation of Mixture

Adsorption in Metal-Organic Frameworks

on

Monday, March 11th at 10:00 a.m.

Bunger-Henry 388

Abstract

Traditional separations necessitate high energy usage and thus have great costs and significant environmental impact associated with their operation. Adsorption systems have garnered much attention in recent years as replacement technologies for many of these conventional separations processes. As separations inherently involve mixtures, understanding adsorption from real mixtures, a complex process, is crucial for widespread industrial implementation. A significant amount of complexity arises from the wide variety of adsorbents from which to choose. One class of adsorbent is that of metal-organic frameworks (MOFs), porous materials comprised of inorganic nodes connected via organic ligands to yield structures with large surface areas and a significant degree of tunability. These materials have been heavily investigated for their potential to address separations problems with significant specificity due to their tunable nature. As measuring experimental mixture adsorption directly has yet to be widely implemented due to its relative difficulty compared to single-component adsorption experiments, many have turned to mixture adsorption prediction methods such as molecular simulations.

GCMC (Grand Canonical Monte Carlo) predictions of mixture adsorption in MOFs have been compared to those from IAST (Ideal Adsorbed Solution Theory), a popular method for predicting mixture adsorption, with experimental mixture adsorption measurements in three MOFs providing the basis against which to test these predictions. The merits and drawbacks of both prediction methods in the studied systems are considered both quantitatively and qualitatively. GCMC simulations are then leveraged to investigate adsorption systems which are either difficult or impossible to study with experimental adsorption measurements. Firstly, the significance of MOF characteristics to the relative impacts of electrostatic interactions during adsorption are studied with carbon dioxide and light hydrocarbons as adsorbate species. Secondly, the validity of the Henry adsorption isotherm model is assessed for minor representative impurities within post-carbon capture streams. Through these studies, the thesis work presented aims to aid the understanding of molecular simulations’ usefulness in the field of mixture adsorption.