First-Principles-Informed Kinetic Modelling in Operando Catalysis Studies: CO Oxidation on Metal Nanoparticles

Online characterisation of local catalyst activity, for example using plasmonic resonance imaging, and across bed performance, for example using mass spectrometry, can provide powerful insight into the impact of local reaction conditions and surface structural developments on conversion. Unpacking observations at different scales can be challenging - especially in systems where concentration gradients exist, or where surface reconstruction alters the structure and phases present for reaction. In such cases, first-principles-informed kinetic modelling can enable further understanding of structure-activity relationships, energetic and kinetic limitations, and mass transport effects.

Here, we will study CO oxidation on copper, palladium, and palladium-gold (PdAu) nanoparticles in various nano- and micro-reactors using DFT-computed energy landscapes to specify the surface kinetics, and idealised flow models based on flow profiles observed with computational fluid dynamics simulations to describe the change in macroscopic variables across the catalyst bed. Oxide formation is treated using a two-site-type model, enabling comparison with experimentally observed surface activity changes with increasing oxygen concentration. Different surface models for the PdAu catalyst elucidate the impact of binding and activation energies on observed conversion trends. We thus demonstrate the potential utility of simple, multiscale kinetic models in rationalizing typically complex structure-activity phenomena, such as oxide formation, light-off behaviour, and activity restrictions, in operando catalysis studies.