Electrical and electrochemical observation of direct synthesis of hydrogen peroxide in suspension flow micro reactors

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The aim of this project is to gain deeper understanding of the details of the local reaction and transport processes taking place inside a novel membrane microreactor system for multiphase heterogeneously catalysed chemical reactions. This is achieved by use of novel miniaturised sensors integrated in the system combined with space and time-resolved numerical simulations. The direct synthesis of hydrogen peroxide from hydrogen and oxygen on palladium-based supported noble metal catalysts has been selected as an application case. This reaction is currently a topic of high interest in catalysis, and it is also well suited for being performed in microreaction systems. For this application, a strategy for adjusting the hydrogen to oxygen concentration ratio in order to decrease in the direction of flow in the membrane microreactor has ben developed in the previous project, which shall now be put in practice and evaluated together with an improved reactor design relying on catalyst-coated thin-walled metallic 3D-printed fluid guiding structures. For space and time-resolved measurement of the concentrations in real time electrochemical sensors have already been developed and successfully integrated into the reactor for pressures up to 100 bars in the previous project. The micro reactor system also includes a membrane for bubble-free dosage of both gaseous reactants directly into the reaction medium flowing along an adjacent meander-like micro channel system. This way of conducting the reaction offers the potential for safe operation of the microreactor system with, at the same time, high selectivity and productivity. This is because the concentration ratio of hydrogen versus oxygen can be adjusted to an optimal value for the catalysed reaction even locally by separate alternating continuous dosing of the two reactants via the membrane. This shall be proven experimentally and also be reproduced quantitatively by simulation. This will also require further improvements of the sensors regarding the detectable concentration range and the applicable reaction media. As a perspective, the knowledge generated shall be used for development of a new intensified technology for efficient and cost-effective local production of hydrogen peroxide as a green oxidant for chemical applications.