Oscillating droplet reactor – towards kinetic investigations in heterogeneous catalysis on a droplet scale

In this work we present a new concept of a millistructured capillary reactor setup for contactless kinetic measurements via in-line Raman spectroscopy for three phase reactions in single slugs. With this setup, it is possible to decouple the residence time from the volumetric flow and the reactor length. Catalysts palladium supported on carbon, in the form of Pd nano-particles on graphite fibres as well as in the form of a fixed bed catalysts as particulates of porous carbon, were utilised. A 3D-printed catalyst holder was designed to integrate the catalyst powder with a fixed bed in the capillary. The proof of concept was demonstrated using two test reactions, namely the hydrogenation of nitrobenzene and cinnamaldehyde. Multiple measurements were carried out and a good reproducibility was achieved, which lays the foundation for the application of this 3-phase oscillating droplet reactor as a tool for assessing kinetics with respect to heterogeneously catalysed three phase reactions.