Annular flow microreactor: An efficient tool for kinetic studies in gas phase at very short residence times

•The thermal behaviour and hydrodynamics in annular and tubular flow microreactors are studied.•The target conditions are very short residence times (10–100 ms) and high temperatures (873–1273 K).•The annular flow microreactor leads to a flatter temperature profile than the tubular flow microreactor.•The annular flow microreactor also leads to less axial dispersion in laminar regime.

This study deals with the modelling of a tubular flow microreactor and an annular flow microreactor that are used for kinetic studies of thermal reactions (873–1273 K) at very short residence times (10–100 ms). The construction of a kinetic model on the basis of experimental reaction data requires the precise characterization of the thermal behaviour and the hydrodynamics of the reactor. In kinetic studies, the reactor is usually considered as an isothermal Plug Flow Reactor. In this paper, we demonstrate that an annular flow microreactor used at very short residence time not only leads to a temperature profile which is better controlled than in a tubular flow microreactor, but also to less axial dispersion for laminar flow. The comparison between both reactors is performed on the basis of temperature measurements, RTD measurements at room temperature, dimensionless numbers calculations and Computational Fluid Dynamics in typical reaction conditions.

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