Structure-dependent microkinetic modeling of the CO2 desorption with surface diffusion

The interaction of CO 2 with Ni catalysts is important for many industrial processes like methanation, which is known to be structure sensitive. Consequently, structure-dependent multiscale modeling is required to accurately capture the interaction of CO 2 with the various Ni facets and to provide accurate atomistic insights. While mean-field multiscale models can be constructed for multifaceted nanoparticles, surface diffusion of adsorbates between the facets is often not considered. In this study, we close the gap by extending the open-source Cantera toolkit with a universal framework for surface diffusion between facets in mean-field microkinetic models, making it the first widely adopted software tool that includes these features. We leverage these updates to develop a thermodynamically consistent microkinetic model for a Ni nanoparticle consisting of Ni(111), Ni(100), Ni(211), and Ni(110) using data from DFT calculations and single-crystal experiments to unravel the interaction of CO 2 with these facets through the simulation of temperature-programmed desorption profiles. Including surface diffusion and coverage effects into the mean-field microkinetic model leads to a significantly improved agreement between experiments from a catalyst and the simulations. Through rigorous correlated uncertainty quantification of all structural and energetic parameters, we are able to identify a microkinetic model within the uncertainty space that is in excellent agreement with the recorded desorption profile. This model highlights that Ni(110), which contributes only to a small extent to the overall Ni surface area, dominates the desorption pattern and that surface diffusion plays a crucial role. The Cantera implementation is generic and can be applied to other metal nanoparticles and metal/metal oxide interfaces, providing a step towards closing the material gap. • Multifacet modeling with surface diffusion is available in Cantera. • Microkinetic mechanism is developed for CO 2 TPD on Ni(111), Ni(100), Ni(211), and Ni(110). • Coverage dependence and surface diffusion are critical to the model agreement.