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Abstract:
A first-principles based multiscale modeling approach to heterogeneous catalysis
is presented, that integrates first-principles kinetic Monte Carlo simulations
of the surface reaction chemistry into a fluid dynamical treatment of the
macro-scale transport in the reactor. Using the CO oxidation at RuO2(110) as
representative example the relevance of first-principles kinetic Monte Carlo is
demonstrated by the comparison with the commonly employed, but less accurate
rate equation based approach to surface chemistry. Huge differences between
both approaches in the predicted reactivity and qualitatively wrong predictions
on the ongoing surface dynamics disqualify the latter approach for the use with
first principles input. An efficient general purpose methodology is developed,
which allows for simulations of macroscopic catalytic reactors with the same
speed as mentioned empirical approaches, but retains the sound electronic basis
and the accurate treatment of surface chemistry by kinetic Monte Carlo simulations.
As a simple showcase the developed method is applied to stagnation
flow fields in front of a RuO2(110) single crystal surface. The simulation results
show how heat and mass transfer effects can readily affect the observed catalytic
function at gas-phase conditions typical for modern in situ experiments. For a
range of gas-phase conditions we furthermore obtain multiple steady-states that
arise solely from the coupling of gas-phase transport and surface kinetics. This
additional complexity needs to be accounted for when aiming to use dedicated
in situ experiments to establish an atomic-scale understanding of the function
of heterogeneous catalysts at technologically relevant gas-phase conditions
