Ammonia, a widely produced chemical, contributes to more than 1% of fossil energy consumption and plays a significant role in global greenhouse gas emissions. Therefore, exploring alternative processes to the Haber-Bosch process is of considerable scientific interest.^[1] This contribution presents a two-reactor system designed for the systematic investigation of process parameters in photocatalytic ammonia synthesis, using TiO₂ aerogels. TiO₂ aerogels are able to store large amounts of photogenerated electrons in surface trap states upon illumination in water−methanol mixtures.^[2] The designed setup splits the processes of photocharging and nitrogen reduction into two different reactors. The first reactor is dedicated to photocharging TiO₂ aerogels, preparing it for N₂ reduction. In this reactor, TiO₂ aerogels are exposed to controlled UV-LED irradiation, focusing on maximizing the storage of photogenerated charge carriers within the TiO₂ structure. The second reactor is dedicated to reducing nitrogen with the electrons in the aerogel stored by utilizing Taylor-flow conditions for enhanced mass transfer and nitrogen reduction efficiency. This reactor is engineered to maximize the contact between nitrogen and the photocharged aerogels, ensuring a more efficient and controlled reduction of nitrogen to ammonia. This study includes characterization of the photocharging reactor and an analysis of the operational parameters of both reactors. The effects of photocharging conditions and flow rates on the overall efficiency of ammonia production were investigated. Concluding this contribution, the potential of this two-reactor system in ammonia production will be discussed. The separation of photocharging and nitrogen reduction processes, combined with the use of Taylor flow, presents a significant advancement in photocatalytic ammonia synthesis. This system offers a more flexible approach to ammonia production, and fundamental understanding of both photocharging and N₂ reduction process.

Quantification of ammonium at very low concentrations represents an enormous challenge and generally conventional methods are time-consuming. The indophenol method that utilizes salicylic acid, sodium hypochlorite and sodium nitroferricyanide, usually requires about 80 to 120 minutes per sample which is not only time-consuming but can be limiting for studies with a large number of samples. To minimize the effort of ammonia detection, an automated yet simple and cheap setup was established utilizing syringe pumps and a temperature-controlled reactor, finally providing the possibility for online monitoring of experiments.^[3] This setup will be presented as well.