457943 Multiscale Simulation of Heterogeneous Catalysis: Butadiene Hydrogenation from Molecular Reaction Steps to the Fluid Flow
Using periodic plane wave density functional theory calculations,2 the hydrogenation reactivity of the simplest poly-unsaturated hydrocarbon, butadiene, on the Pd(111) surface has been investigated. The effect of the hydrogen coverage on the Pd(111) surface has been accounted for in order to model different macroscopic reaction conditions. The most important energy barriers have been exactly determined using the Nudge Elastic Band method3 while transition states suspected to have a higher potential energy have been estimated using a Bronsted-Evan-Polanyi relationship.4Using transition state theory, the hydrogenation energy profile at low hydrogen coverage, developed in an earlier stage of the project, has been used to build a first implementation of a micro-kinetic model. The PeliGRIFF CFD code developed at IFP Energies Nouvelles has been upgraded in order to include for the first time a reaction term in the catalyst grain. The obtained kinetic law has been included in PeliGRIFF and it was shown that with intra-grain diffusion coefficient one order of magnitude lower than the gas phase diffusion, the reaction mainly happens in a shell surrounding the grain.
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