Simulation of catalytic reactions in open-cell foam structures

We present a technique for particle-based simulation of heterogeneous catalysis in open-cell foam structures, combining isotropic Stochastic Rotation Dynamics (iSRD) with Constructive Solid Geometry (CSG). The method is validated against experimental data for the low-temperature water-gas shift reaction in an open-cell foam modeled as an inverse sphere packing. Analysis of the relation between the Sherwood and Reynolds numbers reveals two distinct regimes that intersect at a strut-scale Reynolds number of approximately 10. For typical parameters from the literature, we show that the catalyst density within the washcoat can be significantly reduced without notable loss of conversion efficiency. Further reduction, however, shifts the system toward the reaction-rate-limited regime, resulting in a marked decline in conversion. For the low-temperature water-gas shift reaction, we additionally vary the porosity to identify optimal foam structures that balance low flow resistance with high conversion efficiency. Large porosity values are found to be advantageous not only in the mass-transfer-limited regime but also in the intermediate regime.