Structure-Reactivity Relationship for Nano-Catalysts in the Hydrogenation/Dehydrogenation Controlled Reaction Systems.

Abstract

Fast yet accurate prediction for the activity of a nanostructured catalyst is an essential but challenging task in heterogeneous catalysis. Despite some successful attempts on describing energetic parameters in different adsorption environments, a general solution to building direct structure-reactivity relationship quantitatively has not yet been established. On the basis of the first-principle-based kinetic Monte Carlo simulations, we developed a kinetic model to build the adsorption site dependence of the activity for reaction systems which are controlled by the hydrogenation/dehydrogenation processes. We applied this kinetic model to investigate the size- and shape-effects of Cu nano-catalysts in the water-gas shift reaction. By accumulating the activities of different adsorption sites, our model satisfactorily reproduced the experimental apparent activation energies for nano-catalyst with size over hundreds of nanometers, which were out of reach for conventional first-principle-based kinetic Monte Carlo simulations. Our results disclose that, even for a cubic nano-catalyst with size of 877 nm, its activity can still be closely related to the activity of edge sites, instead of only the exposed Cu(100) facets as might have been expected. The present model is expected to enhance the kinetic investigations of various chemical systems of interest, especially in chemical systems that are important in hydrogen economics.