Catalytic static mixers for flexible and scalable hydrogenation reactions in continuous flow

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INTRODUCTION
Hydrogenation reactions represent a substantial proportion of chemical transformations in a manufacturing environment. Whilst bulk chemical manufacturers are well-accustomed to using continuous processing for this type of reaction, its application in fine chemicals (including the pharmaceutical industry) is far less common. That said, continuous flow hydrogenations have also recently begun to gain traction in the pharmaceutical industry, due to the improved safety profiles, higher productivity for the reactor footprint and simplified catalyst handling (1,2). The majority of applications make use of packed bed reactors (3-6), which are a well-explored reactor type, allowing highly productive hydrogenation reactions in flow. However, these require specific design and detailed testing, regarding their dimensions, particle size, heat transfer, packing character, etc. Even more problematic, is that, in some cases, this optimization process may need to be repeated when moving from lab scale toward pilot and manufacturing. Although this is not always the case, additional planning must be incorporated to ensure that pressure drop on larger scale will be manageable with small particle size. Most critical are the pressure drop and heat transfer, which can both cause bottlenecks to reaction throughput, especially for exothermic reactions. Owing to the complexity of these reactions and their numerous challenges, many reaction engineering solutions have been proposed (7).