(504b) First Principles Modeling of Extended Solvent Structures in Defected Microporous Materials and Their Influence on the Kinetics of Lewis Acid Site Speciation
AIChE Annual Meeting
2018
2018 AIChE Annual Meeting
Catalysis and Reaction Engineering Division
Computational Catalysis V: Oxides, Zeolites, Porous Catalysts, and Supported Catalysts
Wednesday, October 31, 2018 - 12:48pm to 1:06pm
Experimental IR spectroscopy is used to observe the changes in hydrogen bond networks in low-defect and high-defect materials compared to those calculated with AIMD. We find that defect-free materials have low water uptakes at ambient conditions, but Sn sites nucleate water clusters. Silanol nests, formed through silicon vacancies introduced during synthesis, generate large extended water networks. The degree of clustering and transience of hydrogen bonding is analyzed using a graph theory approach to define membership rules for water clusters and extended networks. These results are then used to study the dissociation of water to form open Sn sites and study the role of liquid water on the relative populations of open and closed sites. Control of the relative populations of open and closed Sn sites, as well as the structure of the surrounding water network, has direct implications on the selectivity and rate of reactions catalyzed in microporous materials.
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