Authors: Duch, Karsten
Source: DepositOnce (article, 2025-01-01)
Field: Chemistry — Organic Chemistry

Investigation of process development and operating strategies for microemulsion systems as reaction media at mini-plant scale A transformation of the chemical industry towards more sustainable products and production routes is urgently required. To achieve this goal, 12 principles of green chemistry have been postulated, but their implementation requires the development of new process concepts that enable atom-efficient catalysis, the use of green solvents and mild process conditions, and the retention of catalysts to reduce waste production. Microemulsion systems (MES) as reaction media offer a way to combine these aspects in one process by solubilizing the homogeneous catalyst in a polar water phase and creating a large interfacial area with the reactant/product phase of opposing polarity through the addition of surfactants. Usually, valuable transition-metal catalyst complexes are used, which can be recovered in active form after the complex reaction network of the reductive amination also requires the investigation of optimal process concepts and operating strategies with which the aldol side product formation can be directly influenced and reduced. A new cyclic semi-batch process concept is developed through elementary process function optimization and implemented successfully in a further 125 h mini-plant operation. Since the separation of the reaction mixture for a successful catalyst retention is usually the biggest operational challenge in an MES process, an extensive experimental analysis of the complex microemulsion separation behavior is required for each new reaction system. Most of the experimental steps were thus far completed manually and a new automated experimental setup with machine learning image recognition and an automated result data-handling procedure is developed to significantly reduce the experimental effort. Different reactions and process designs have been demonstrated successfully and essential experimental investigations were automated. Thus, combined with previous work in the field of MES as reaction media, all necessary tools for an investigation of MES on a laboratory and mini-plant scale have been developed and tested to enable the fast implementation of new reactions in MES on an industrial scale. reaction through simple temperature-controlled phase separation. MES enable catalyst recovery rates of more than 99%, which is essential for the economic viability of the process. In addition to intense laboratory research of MES as reaction media, a continuous MES process operation has been successfully demonstrated for the hydroformylation of dodecene on a mini-plant scale. However, to establish MES reaction media in an industrial process, further more complex reaction networks need to be scaled-up to a mini-plant and different process designs and reactor operating concepts need to be investigated. In this thesis, the reductive amination of undecanal is implemented in a CSTR mini-plant process as an example of a complex reaction network with multiple side, subsequent, and equilibrium reactions, to demonstrate the wide range of applications of microemulsion systems as reaction media. A continuous plant operation for the new MES reaction system is demonstrated for over 200 h with good reaction performance, stable phase separation, and excellent catalyst recycling (&gt;99%), thus demonstrating a successful scale up from the laboratory by a factor of 68. The complex reaction network of the reductive amination also requires the investigation of optimal process concepts and operating strategies with which the aldol side product formation can be directly influenced and reduced. A new cyclic semi-batch process concept is developed through elementary process function optimization and implemented successfully in a further 125 h mini-plant operation. Since the separation of the reaction mixture for a successful catalyst retention is usually the biggest operational challenge in an MES process, an extensive experimental analysis of the complex microemulsion separation behavior is required for each new reaction system. Most of the experimental steps were thus far completed manually and a new automated experimental setup with machine learning image recognition and an automated result data-handling procedure is developed to significantly reduce the experimental effort. Different reactions and process designs have been demonstrated successfully and essential experimental investigations were automated. Thus, combined with previous work in the field of MES as reaction media, all necessary tools for an investigation of MES on a laboratory and mini-plant scale have been developed and tested to enable the fast implementation of new reactions in MES on an industrial scale. Microemulsion ; Process development ; Process (computing) ; Catalysis ; Separation process ; Process control ; New product development ; Chemical reaction engineering ; Chemical reaction Surfactants and Colloidal Systems ; Mesoporous Materials and Catalysis ; Advanced Polymer Synthesis and Characterization