(522c) Resolved-Pore CFD Simulation of CO Oxidation in a Catalyst Layer

Resolved-Pore CFD Simulation of CO Oxidation in a Catalyst Layer

Behnam Partopour, Anthony G. Dixon

Department of Chemical Engineering, Worcester Polytechnic Institute, Worcester, MA

CO oxidation is a very fast reaction with one of the simplest microkinetics models available in the literature. The reaction has important environmental and industrial applications, and therefore, has been studied significantly. The focus of most studies, though, has been the atomic behavior of the active sites and reaction kinetics. CO oxidation is usually carried out in monolith reactors. The interactions of transport, reaction and the flow field in these systems can define the efficiency of the process. Therefore, multiscale models of these systems are highly desired.

In this study, we present a workflow for numerical construction of the catalyst layer, generation of a volumetric mesh for the constructed geometry, and finally, computational fluid dynamics (CFD) integrated multiscale simulation of the reaction in the layer. We validated the constructed catalyst layer properties,

e.g. pore size distribution, with available data in the literature. Then, we developed a code to couple the flow in the macro-pores with transport and surface reaction. A microkinetics model developed by Karadeniz et al., (2013) is used to represent the surface reaction.1 The results show important points: 1- Significant velocity gradients in the pores; 2-Reaction is very fast and species concentration gradient on the surface is significant; 3- The reaction is locally controlled by the ratio of available surface area to the volume of the pores; 4- A change in velocity profile does not affect the reaction considerably. The suggested workflow could be used to enhance our understanding of the diffusion models in the macro- porous medium.

CFD simulation for micro-structure

Micro particles size distribution2

Simple force model to pressurize the particles

References:

1. Karadeniz, H.; Karakaya, C.; Tischer, S.; Deutschmann, O. Numerical Modeling of Stagnation-Flows on Porous Catalytic Surfaces: CO Oxidation on Rh/Al2O3. Chem. Eng. Sci. 2013, 104, 899–907

2. Novak V, Koci P, Marek M. Multi-scale modeling and measurements of diffusion through porous catalytic coatings. Catal. Today. 188 (2012) 62–69.