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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 (R e 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. [Display omitted] • Comparing single particle CFD & continuum model simulations for n -butane oxidation • Continuum model representation can lead to erroneous intraparticle profiles • Description of surface conditions decisive under external transport limitation [ABSTRACT FROM AUTHOR]

This work reports the results of a perspective workshop held in summer 2021 discussing the current status and future needs for multiscale modeling in reaction engineering. This research topic is one of the most challenging and likewise most interdisciplinary in the chemical engineering community, today. Although it is progressing fast in terms of methods development, it is only slowly applied by most reaction engineers. Therefore, this perspective is aimed to promote this field and facilitate research and a common understanding. It involves the following areas: (1) reactors and cells with surface changes focusing on Density Functional Theory and Monte-Carlo simulations; (2) hierarchically-based microkinetic analysis of heterogeneous catalytic processes including structure sensitivity, microkinetic mechanism development, and parameter estimation; (3) coupling first-principles kinetic models and CFD simulations of catalytic reactors covering chemistry acceleration strategies and surrogate models; and finally (4) catalyst-reactor-plant systems with details on linking CFD with plant simulations, respectively. It therefore highlights recent achievements, challenges, and future needs for fueling this urgent research topic in reaction engineering. • Surface changes are highly dependent on local conditions. • They require models bridging from molecular to continuum scale. • Hierarchical microkinetics involves material, mechanism, and parameter estimation. • Coupling kinetic models with CFD must be sped-up or surrogate modeled. • Catalyst-reactor-plant systems are based on CFD with abstraction to higher scales. [ABSTRACT FROM AUTHOR]