Downer fluidized bed reactor modeling for catalytic propane oxidative dehydrogenation with high propylene selectivity

This study reports a simulation of the catalytic propane oxidative dehydrogenation (PODH) in a circulating fluidized bed downer reactor. A relevant kinetics based on experimental work by the authors (Rostom and de Lasa, 2018), developed in a fluidized CREC Riser Simulator is considered. As well, Computational Particle Fluid Dynamics (CPFD) models featuring either "Particle Clusters" or "Single Particles" flows are implemented. The CPFD results obtained in a 20-m length unit show a 28% propane total conversion and 93% propylene selectivity using the "Single Particle" flow model. However, and once the more rigorous particle cluster flow is accounted for, the propane conversion is reduced significantly to 20%, while the propylene selectivity remains at 94% level. Thus, the obtained results show that, a PODH simulation using CPFD, requires one to account for "Particle Clusters". This type of comprehensive model is required to establish unambiguously the downer reactor performance and is of critical value for the development of downflow reactors for other catalytic processes.