(45g) A Multiscale Modeling Strategy for Monolith Reactors

Computationally fast modelling strategies for structured reactors, particularly monoliths, are imperative for fast development of new processes. Due to computational limitations, monoliths are modeled as a continuum in full-scale catalytic reactors models without any rigorous evaluation of the effective properties and reaction rates. The accuracy of these models reduces significantly when the properties of the solid and fluid phases differ significantly or the Damköhler number associated with the heterogeneous reactions is large. To this end, we introduce a multiscale methodology for monolith reactors combining the asymptotic and volume averaging techniques to render the original multiphase reactor as a single phase. The methodology takes advantage of the large separation in length scales to calculate the effective properties, such as the thermal conductivity and permeability and heterogeneous reaction rates. For verification, the predictions of our modeling strategy are compared against the three-dimensional detailed simulations (resolving the solid and fluid phases) for elementary and complex global kinetics of different orders. Our methodology is able to accurately predict the species concentration for arbitrarily large Damköhler number. The developed methodology reduces the computational cost by three orders of magnitude while maintaining the accuracy of the detailed simulations.