Resolved-Pore Simulation of CO Oxidation on Rh/Al2O3 in a Catalyst Layer

Abstract

Abstract:Computational fluid dynamics (CFD) is coupled with reaction and transport in a micro-scale pellet simulation to study CO oxidation over Rh/Al 2 O 3 catalyst. The macro-pores are explicitly modeled to study the interaction of these phenomena in both the solid and fluid phases. A catalyst layer is computationally reconstructed using a distribution of alumina particles and a simple force model. The constructed geometry properties are validated using the existing data in the literature. A surface mesh is generated and modified for the geometry using the shrink-wrap method and the surface mesh is used to create a volumetric mesh for the CFD simulation. The local pressure and velocity profiles are studied and it is shown that extreme changes in velocity profile could be observed. Furthermore, the reaction and species contours show how fast reaction on the surface of the solid phase limits the transport of the reactants from the fluid to meso-and micro-porous solid structures and therefore limits the overall efficiency of the porous structure. Finally, the importance of using a bi-modal pore structure in the diffusion methods for reaction engineering models is discussed.

Computational Fluid Dynamics for Fixed Bed Reactor Design

“…Two studies have examined resolved-pore simulations of thin catalyst layers: Bufe et al (62) simulated diffusion and reaction in liquid-filled transport pores for Fischer-Tropsch synthesis to obtain optimal values of catalyst layer thickness and porosity, and Partopour & Dixon (63) simulated CO oxidation in a catalyst layer of Rh/Al 2 O 3 where the macropore structure was explicitly modeled and the interaction between transport and reaction was shown. The coupling of resolved-pore modeling in catalyst pellets with resolved-particle modeling of the fixed bed is a level of simulation that is not yet achievable given present computational abilities.…”

Mass transfer towards a reactive particle in a fluid flow: Numerical simulations and modeling

“…Wehinger et al (2017) also performed numerical simulations for a single catalyst sphere with three pore models with different com plexities: instantaneous diffusion, effectiveness factor approach and three dimensional reaction diffusion where chemical reaction takes place only within a boundary layer at the particle surface. In Partopour and Dixon (2017b), a computational approach for the reconstruction and evaluation of the micro scale catalytic struc ture is employed to perform a pore resolved simulations coupled with the flow simulations. Dierich et al (2018) introduced a numerical method to track the interface of reacting char particle in gasification processes.…”

Computational Fluid Dynamics of Reacting Flows at Surfaces: Methodologies and Applications

“…They aim at correcting the molecular gas diffusivity by taking into account the properties of the catalytic porous matrix. Hence, analysis of the internal catalyst structures has been performed to properly quantify these properties 38, 39 and effectively adopt the aforementioned models. In doing so, the computational domain is composed of two meshes, one for the fluid and a second for the catalytic material, sharing the fluid‐solid interface.…”