Investigating the accuracy of continuum models for the simulation of industrial maleic anhydride reactors: A comparative single particle CFD study

The selective oxidation of n-butane to maleic anhydride is a strongly exothermic reaction. Resulting local hot-spots and intraparticle temperatures high above the surrounding fluid temperature are challenging for safe and economic operation of reactors. Detailed modelling on all length scales is therefore required for an accurate description of this process. In this contribution, the one dimensional description of the ring-shaped catalyst, commonly used in continuum reactor modelling, is compared to three dimensional computational fluid dynamics simulations for the case of a single catalyst particle at different inclination angles (0 to 90°). Polytropic chemical reaction is considered under typical n-butane oxidation conditions ($Re_p=400$), representing a catalyst particle close to the inlet, ($T=673$ K) and at the hot-spot ($T=730$ K) of an industrial reactor. Comparative analysis suggests that the one dimensional simplification is justified when external transport phenomena are not the limiting resistance. Otherwise, neglecting two spatial dimensions leads to erroneous predictions.