Northwestern University Evanston Campus Evanston United States
The objective of this research was to identify new sorbents for removal of toxic compounds including ammonia, phosphine, arsine, and methyl bromide from air, particularly in the presence of humidity. Included in this goal was the systematic computational study of strong chemisorption of target molecules and functionalized surfaces, including nanoporous metal-organic framework MOF materials, as well as functional groups and metal catecholates that could be incorporated into MOFs to improve adsorption of the target molecules. Cu-MOF-74Cu-CPO-27 and ZIF-78 are predicted to be good sorbents for ammonia in the presence of humidity. We devised an efficient way to identify hydrophobic MOFs using Henrys constants and screened 137,953 hypothetical MOFs, finding 2777 hydrophobic structures which are selective for ammonia instead of water. Aromatic rings modified with a variety of functional groups were screened for interactions with ammonia, phosphine, and water. We predict that groups containing transition metals like copper and silver provide the strongest binding and best selectivity over water. A number of metal catecholates were tested for binding strength with ammonia, phosphine, arsine, and methyl bromide, and promising targets were identified.