Electrochemical Reaction Engineering
In May 2020, Prof. Dr. Anna Mechler was appointed Professor for “Electrochemical Reaction Engineering” (AVT.ERT), which is funded by a generous donation of Covestro. Prof. Mechler is also a research group leader at IEK-9 of Forschungszentrum Jülich. The chair researches electrochemical processes with a focus on electrocatalysis and how it is affected by external reaction parameters.
The research of the AVT.ERT concentrates on converting electrical energy into chemical energy and vice versa. These processes require catalytically active materials for efficient conversion. The focus areas are heterogeneous processes, involving the surface of a solid material. The conversion occurs at the solid-liquid or solid-liquid-gaseous interface. Therefore, the electrode performance does not only depend on the catalyst material itself, but also on the properties of the whole reaction system.
During a reaction, the system is subject to change. Educts are consumed continuously, which introduces a concentration gradient over the active catalyst area. The catalyst itself can alter its composition due to agglomeration, degradation, or poisoning effects, which also influence the electronic and geometric surface structure. Our research focuses on how different reaction parameters change the electrode and its interface. A powerful tool is online mass spectrometry. The product feed from the electrochemical cell is directly analyzed for the mass of products, educts, and impurities. This information helps us to understand how the system changes during the reaction.
Different reaction parameters can have various effects on electrochemical conversion. Temperature and flow rate influence the catalyst stability and can be adjusted for performance enhancements. Co-catalysts can also be introduced to decrease degradation. The influence of additional ions in the electrolyte can interfere with the reaction ranging from increasing the activity to poisoning the catalyst. Knowledge of the functionality of each parameter and changes during the reaction allows for optimization of the reaction conditions and tailor-made catalysts.
A structured electrode design is also integral for optimal catalyst usage. The catalyst itself has a certain surface geometry that can influence product selectivity. However, the optimal selectivity does not always correspond to the maximum surface area. These effects need to be considered during scale-up as industrial processes require surfaces a few orders of magnitude larger than the laboratory scale. Other problems are pore-diffusion, temperature and concentration gradients, and material conductivity. The knowledge of these effects is crucial for transforming lab-scale electrochemical cells into industrial reactors.