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TY  - THES
AU  - Gaelings, Niklas
TI  - Development of tailored multiphase reaction systems for the catalytic synthesis of cyclic and linear acetals
PB  - RWTH Aachen University
VL  - Dissertation
CY  - Aachen
M1  - RWTH-2026-01456
SP  - 1 Online-Ressource : Illustrationen
PY  - 2026
N1  - Veröffentlicht auf dem Publikationsserver der RWTH Aachen University
N1  - Dissertation, RWTH Aachen University, 2026
AB  - The increasing amount of greenhouse gases in earth’s atmosphere is the reason for global warming. The transportation sector is responsible for a fifth of global greenhouse gas emissions. To reach the goals of the Paris climate agreement it is urgent to reduce these emissions. Using renewable drop-in fuels could help to reduce the emissions of the current fleet of cars with combustion engines, heavy duty vehicles, and sectors that cannot be electrified easily. Within the “Fuel Science Center” cluster of excellence cyclic acetals (CAs) are investigated as novel renewable fuels. Cyclic and linear acetals (LAs) are also interesting as novel monomers for polyacetals. A method for the synthesis of CAs and LAs from CO2, H2 and diols, catalyzed by a homogeneous Ru-triphos catalyst, was developed in the Klankermayer group in 2019.In this thesis two multiphase reaction systems for CA and LA production were developed that allow for the easy separation of catalyst and products. The concept for CA production exploits the difference in polarity between CA and diol substrate. The cationic Ru-triphos catalyst was immobilized in the polar diol substrate while the less polar CA product was extracted in situ by nonpolar n-decane. The multiphase approach additionally mitigated a severe limitation of the reaction by the thermodynamic equilibrium, shifting the equilibrium towards the product side by removing the product from the reaction by extraction. After optimization of the reaction conditions and development of a tailored recycling procedure, a recycling experiment over ten consecutive runs resulted in a total TON of 2177. The concept was shown to be applicable for a range of diol substrates. The system for LA production utilizes the cationic nature of the ruthenium catalyst to immobilize it in an ionic liquid (IL) while the products were separated via the diol layer. [OMIM][NTf2] was found to be the most suitable IL for this task. After optimization of the reaction conditions with ethylene glycol as substrate the catalyst was recycled for eight consecutive runs with a total TON of 1755 for the linear acetal. The IL was found to stabilize the catalyst, resulting in minimal catalyst deactivation. A diol screening showed the general applicability of the system for multiple diol substrates. The diol screening indicated the necessity to specifically tailor the IL for each diol, as cross miscibility of diol and IL was discovered to be an issue for longer chain diols, leading to losses of catalyst and IL.
LB  - PUB:(DE-HGF)11
DO  - DOI:10.18154/RWTH-2026-01456
UR  - https://publications.rwth-aachen.de/record/1028105
ER  -