TP4: Multiscale analysis of reaction‐transport interactions in e‐HP

Marlon Ritz

Motivation and objectives:
Reactions at catalysts inevitably lead to reactant accumulation or depletion close to the sur-face. Therefore, it is not the electrode reaction rates but the species transport and reactions in the electrolyte that dominate the performance and selectivity under certain operating condi-tions. In this project, the macrokinetics of the electrochemical synthesis of H₂O₂ are investi-gated using experimentally parameterized and validated mechanistic models in three setups with strongly different microenvironments. The setups range from a liquid-phase rotating disc electrode setup with a flat electrode, via liquid-phase continuous flow reactors used for com-parison with t-HP, to technical-scale flow cells with porous gas diffusion electrodes. The set-up-specific models are used to quantify the impact of transport, reactions, side reactions and the resulting electrolyte conditions on defined performance indicators, such as selectivity, productivity, and energy efficiency. The conditions, limitations, and performance indicators are compared between the different setups and also with t-HP. The short-circuited state of electrochemical cells is compared to the t-HP reactor in order to evaluate the extent to which chemical reactions can be considered as a short-circuited electrochemical reaction. These analyses will lead to ideas for adjusting a beneficial mass-transport regime in reactors or cells in order to improve the performance or comparability.