The development of new flow-compatible high-performance catalysts requires the understanding of the activity of the material in the nanometric scale. Here we use a combination of fluorescence and electron microscopy, in-flow single molecule fluorescence, and bench chemistry, combined with a fluorogenic system, allowing an intimate understanding of the properties and performance of palladium on glass wool (Pd@GW) in the nitro-to-amine catalytic reduction. The process is monitored starting from the nitro-compounds' reversible association with catalytic centers, to the behavior, interaction, and departure of reduced amine products. The catalyst used, Pd@GW, is ideal for flow heterogeneous catalysis applications requiring a fixed bed catalyst. Using advanced microscopy techniques, we are able to fully characterize our catalyst in situ, providing deep insight into the catalytic abilities of the material. We also explore under flow conditions if Pd clusters could migrate and redeposit elsewhere on the surface of the heterogenous support. Overall Pd migration seems to be minimal over several hours, with the catalyst stability assisted by APTES anchoring. Further, some active Pd sites seem to have enhanced catalytic activity after reaction, as evidenced by in situ imaging of the catalyst. This deep understanding of the real activity of heterogeneous catalysts will help researchers to improve present catalysts and explore new catalysis systems.

Silver nanoparticles have become one of the most commercially and industrially relevant nanomaterials of the 21st century, owing to their potent antibacterial properties, as well as their useful catalytic and optical properties. Although many methods have been explored to produce AgNPs, we favor the photochemical approach using photoinitiators to produce AgNPs, owing to the high degree of control over reaction conditions, and the generation of so-called AgNP ‘seeds’ that can be used as-is, or as precursors for other silver nanostructures. In this work, we explore the scale-up of AgNP synthesis using flow chemistry and assess the usefulness of a range of industrial Norrish Type 1 photoinitiators in terms of flow compatibility and reaction time, as well as the resulting plasmonic absorption and morphologies. We establish that while all the photoinitiators used were able to generate AgNPs in a mixed aqueous/alcohol system, photoinitiators that generate ketyl radicals showed the greatest promise in terms of reaction times, while also showing greater flow compatibility compared to photoinitiators that generate 𝛼-aminoalkyl and α-hydroxybenzyl radicals. These findings help to establish a guideline for adapting photochemical AgNP syntheses to flow systems, helping to improve the scalability of the method in one of the largest industries in nanomaterial chemistry.

In this work, we propose an automated, real-time optical scanning approach to assessing catalyst performance in the process of nitro-to-amine reduction using well-plate readers to monitor reaction progress. This approach takes advantage of a simple on–off fluorescence probe that gives a shift in absorbance and strong fluorescent signal when the non-fluorescent nitro-moiety is reduced to the amine form. The combination of an affordable probe and a low barrier-to-entry technique provides an accessible approach to high-throughput catalyst screening. Under this paradigm, we screened 114 different catalysts and compared them in terms of reaction completion times, material abundance, price, recoverability, and safety. Using a simple scoring system, we plotted the catalysts in terms of cumulative scores, along with some intentional biases, including an emphasis on preference for catalysts with potential as green catalysts, considering environmental issues and possible geopolitical preferences.

In this work, we propose an automated, real-time optical scanning approach to assessing catalyst performance in the nitro-to-amine reduction using well-plate readers to monitor reaction progress. This approach takes advantage of a simple on-off fluorescence probe that gives a shift in absorbance and strong fluorescent signal when the non-fluorescent nitro-moiety is reduced to the amine form. The combination of an affordable probe and a low barrier-to-entry technique provides an accessible approach to high-throughput catalyst screening. Under this paradigm, we screened 114 different catalysts and compared them in terms of reaction completion times, material abundance, price, recoverability, and safety. Using a simple scoring system, we plotted the catalysts in terms of cumulative scores, along with some intentional biases, including an emphasis on preference for catalysts with potential as green catalysts, considering environmental issues and possible geopolitical preferences.