Orifice microreactor for the production of an organic peroxide – non-reactive and reactive characterization

Abstract

In this article, the transfer of a two-step, biphasic, and exothermic peroxide synthesis into a microreactor assisted process is discussed as well as the non-reactive and reactive characterization of the developed orifice microreactor. Residence time distribution measurements showed nearly ideal plug-flow behaviour. The Bodenstein number at a flow rate of 21 mL min⁻¹ is 180 and the corresponding cell number is 90, indicating a narrow residence time distribution. The determined residence times at two different flow rates are in good agreement with the theoretical values of 3.2 s and 1.5 s. The influence of flow rate on droplet size distribution is discussed as well as the influence of orifice geometry on the resulting energy density. These measurements showed a very small droplet size distribution over a wide range of flow rates applied. The smallest mean droplet size of 7 μm was obtained for a flow rate of 75 mL min⁻¹. It is shown that a change from baffle type to conical orifices allows increasing of the throughput by keeping the homogenizing pressure similar to the baffle type system at a lower throughput. The measurement of the temperature profile on top of the thin reaction plate, covering the reaction channel is possible due to a special design of the orifice microreactor and enables monitoring the heat production under reactive conditions. A benchmark based on the product output of an industrial semi-continuous process points out the potential of micro process technology to intensify existing processes. On the examples of four fictive production scale microreactor assisted processes, it is shown that the footprint as well as the reaction volume can significantly be reduced. Using an orifice microreactor of the size of a shoebox the calculated space–time-yield for a product output of ca. 196 kg L⁻¹ h⁻¹ is 905 kg L⁻¹ h⁻¹. This is orders of magnitude higher than for the industrial semi-continuous process.