On the Role of Radial Dispersion in the Behavior of a Cooled Fixed-Bed Reactor: Numerical Investigation of Fischer–Tropsch Synthesis with a Cobalt-Based Catalyst

The impact of radial dispersion of both heat and mass on the behavior of cooled fixed-bed reactors was explored using a two-dimensional reactor model. This study accounted for dispersion through an effective radial thermal conductivity (λ_rad) and a radial dispersion coefficient of mass (D_rad), with Fischer–Tropsch synthesis serving as an illustrative process example. Under moderate reaction conditions and hence still rather gentle radial temperature profiles, the effect of mass dispersion on reactor performance was found to be minimal, even if disregarded (D_rad = 0), whereas dispersion of heat (λ_rad) always significantly impacts reactor behavior. Nevertheless, for precise thermal runaway predictions by a reactor model, incorporating mass dispersion by a realistic D_rad value is essential.