CFD modeling of multiphase flows with detailed microkinetic description of the surface reactivity

The analysis of catalytic processes and the development of innovative technologies require a deep comprehension of the complex interplay between the intrinsic functionality of the heterogeneous material and the surrounding environment in the reactor. This is particularly important for multiphase catalytic reactors where complex interactions among the phases distribution, the inter- and intra-phase transport and the catalytic material occur. In this work, a computational framework has been developed to couple the solution of the hydrodynamics of multiphase flow using Computational Fluid Dynamics (CFD) with the detailed description of the surface reactivity through first-principles microkinetic models. In particular, the methodology employs an algebraic Volume-Of-Fluid (VOF) approach for the advection of the phases and takes advantage of the Compressive-Continuous Species Transfer (CST) for the modeling of the species mass interfacial transfer. The heterogeneous chemistry is included as source terms to the mass and energy equations acting at the catalytic surface, while the solution of the mass balance equation employs an operator splitting approach. The numerical framework has been assessed with respect to simple geometries by direct comparison with analytical and fully coupled solutions followed by examples of application in the context of the nitrobenzene hydrogenation to aniline. The envisioned approach is the first step toward the first-principles-based multiscale analysis of multiphase catalytic processes paving the way toward the detailed understanding and development of innovative and intensified technologies.