(301e) Simulating Active Sites, Environments and Their Influence on Catalytic Performance
An atomic scale understanding of the sites that control catalytic reactions could ultimately lead to tremendous breakthroughs in our ability to design more active, selective and stable catalytic materials. Elucidating the nature of the active site requires a detailed understanding of the chemical bonds that form between reactants (as well as intermediates and products) and the specific atoms in active surface sites. The local reaction environment in which the active site sits, however, can be just as important as the active site itself. Specific compositional and structural ensembles that result due to alloying, metal- or metal-oxide- support interactions, and/or the presence of defect sites can significantly change the strength as well as the nature of the adsorbate surface bonds in the active site. In addition, the presence of promoters, solvent, or applied potentials or changes in the operating conditions which control adlayer coverages can also significantly alter bonding at the active site, local reactivity and overall catalytic performance.
Computational chemistry has reached the stage where it can be used to model the atomic structure along with the local molecular topography about proposed active sites and establish their influence on the catalytic reactivity. The ability to connect the local chemistry to overall catalytic performance requires the ability to track the myriad of molecular transformations that occur over the catalyst and ultimately undergo a late-lumping strategy. Professor Bischoff was one the pioneering fathers of kinetic lumping. While the significant advances in computation resources and computational methods have allowed us to simulate complex reaction environments in significant detail, the necessity to follow catalytic performance requires the appropriate lumping to connect the catalytic surface structure with catalytic performance. Kinetic Monte Carlo simulations offer the ability to not only follow the kinetics but also tailor the structural features toward the design of more active catalytic materials. In this talk, we will review some of the advances that have occurred over the past decade and present examples on the simulation of active sites for oxygenate synthesis and electrocatalysis.