Enhancing Reactive\nMicroemulsion Processes: Dynamic\nOptimization and Cyclic Semibatch Operation for the Reductive Amination\nof Undecanal in a Mini-Plant

Achieving the maximum\nproduction rate of a chemical component in\na process requires an optimal process design and operating strategy.\nOne possible approach toward this goal is the elementary process function\n(EPF) optimization where the optimal temperature, pressure, and mass\nflow profiles for a Lagrangian fluid element are determined. In the\ncurrent study, the EPF methodology is applied to the reductive amination\nof long-chain aldehydes in microemulsion systems (MES) to maximize\nthe reaction performance. These solvent systems are a multiphase green\nchemistry approach to combine highly selective homogeneous catalysis\nwith excellent catalyst retention using a water phase. For the reductive\namination in MES, a cyclic semibatch operation is selected as the\nbest approximation of the optimal EPF trajectories. This new process\nconcept is implemented in a modular mini-plant, and successful validation\nof the optimization results is achieved for 19 consecutive semibatch\nreactions during a 125 h mini-plant campaign. The yield (43.8 ±\n3.3) %, selectivity (64.3 ± 5.4) %, and conversion (68.0 ±\n3.4) % are higher than those achieved in a previous mini-plant operation\nusing a CSTR. Especially, the strong increase in selectivity, achieved\nthrough suppression of side product formation, proves that the EPF\ncalculation can lead to a better process design and operating strategy.\n99.1% of the catalyst entering the settler is recycled to the reactor,\nand the reaction performance remains constant for 125 h without requiring\nadditional catalyst. This excellent catalyst retention and long-term\nstability support the results of previous studies, which outline the\nlarge potential of microemulsion systems as reaction media for homogeneous\ncatalysis and their readiness for process implementations.