Stock, Sebastian (2022)
Designing Pickering Emulsions for Interfacial Catalysis.
Technische Universität Darmstadt
doi: 10.26083/tuprints-00022939
Ph.D. Thesis, Primary publication, Publisher's Version
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Item Type: | Ph.D. Thesis | ||||
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Type of entry: | Primary publication | ||||
Title: | Designing Pickering Emulsions for Interfacial Catalysis | ||||
Language: | English | ||||
Referees: | Klitzing, Prof. Dr. Regine von ; Schomäcker, Prof. Dr. Reinhard | ||||
Date: | 2022 | ||||
Place of Publication: | Darmstadt | ||||
Collation: | xiii, 158 Seiten | ||||
Date of oral examination: | 23 November 2022 | ||||
DOI: | 10.26083/tuprints-00022939 | ||||
Abstract: | Pickering emulsions (PEs) are emulsions stabilized by solid or soft (nano-)particles. The high adsorption energy of the particles at the interface results in outstanding stability of PEs. This attribute makes them ideal candidates as an environment for interfacial catalysis. In PEs that are used for interfacial catalysis, usually, a water-soluble catalyst is enclosed in water droplets that are surrounded by the substrate/product containing oil phase. The reaction takes place at the interface of the droplets. The large internal interfacial area of PEs benefits the contact between substrate and catalyst, while the catalyst itself is conserved and protected in the dispersed phase. This increases the product yield and reduces the catalyst loss. Most important, the inherent stability of PEs allows the application of energy-efficient separation strategies, e. g., membrane filtration, to retain the catalyst phase and simultaneously extract the product phase. Despite the growing interest in this topic over the last decade, the connection between emulsion structure and reaction performance remains unclear and general conclusions are missing. This thesis addresses the influence of the emulsion structure on the reaction and filtration performance and suggests a new improved PE structure based on the gained findings. It resembles a bottom-up approach: First, the used nano-particles are characterized regarding their size, charge, hydrophobicity, density and other geometrical characteristics. As a model system, mono-disperse silica nano-spheres (SNs) are synthesized to enable the calculation of values for the particle coverage and the particle-liquid contact area in the PEs. Second, these particles are used to stabilize water in 1-dodecene emulsions and a connection between the nano-scale particle properties and the micro-scale PE structure is drawn. Third, the PEs are tested as an environment for the hydroformylation of 1-dodecene into tridecanal via the water-soluble ligand-metal catalyst Rhodium-Sulfoxantphos and subsequent membrane filtration is carried out. The knowledge about the geometry and structure of the PEs enables the development of a detailed and quantitative model of the reaction process. Finally, a novel emulsion structure is designed based on the findings by combining solid hydrophobic SNs and soft hydrophilic microgel particles (MGs) to synergistically stabilize PEs. The hydrophobic SNs enable the formation of water in oil emulsions while MGs act as a spacer between the SNs to improve the catalyst-substrate contact area. These findings may contribute to a fundamental understanding and offer new impulses for the optimization of interfacial catalysis in PEs. |
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Status: | Publisher's Version | ||||
URN: | urn:nbn:de:tuda-tuprints-229395 | ||||
Classification DDC: | 500 Science and mathematics > 530 Physics | ||||
Divisions: | 05 Department of Physics > Institute for Condensed Matter Physics 05 Department of Physics > Institute for Condensed Matter Physics > Soft Matter at Interfaces (SMI) |
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Date Deposited: | 02 Dec 2022 12:38 | ||||
Last Modified: | 19 Jun 2023 07:54 | ||||
URI: | https://tuprints.ulb.tu-darmstadt.de/id/eprint/22939 | ||||
PPN: | 503359742 | ||||
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