Katalytische Hydrierung in Mehrphasensystemen auf Basis von ionischen Flüssigkeiten und Kohlendioxid

Carbon dioxide (CO2) and ionic liquids (ILs) have been intensively studied as solvents in catalysis. The combination of ILs and CO2 and its interaction with third components has attracted only sparse interest in research. In the literature, the IL/CO2 system is discussed as a promising technique for continuous flow reactions. In order to improve the process design a broadening of knowledge on the interaction between CO2 and ILs as well as related effects is required. Gas solubility is a critical physical property in reaction involving a gaseous substrate. Due to its very low solubility and very low molar mass, H2 solubility in ILs is below the detection limit of commonly used measurement techniques. In this work a method is optimised to reliably detect H2 concentrations in ILs and also in the presence of a third component such as CO2 or C2H4. This technique has been applied on various ILs for measurements under pure H2-atmosphere and under CO2/H2 and C2H4/H2 gas mixtures. One further important physical property in the IL/CO2 system is the viscosity of the IL. Viscosity is directly related to the mass transport. For example, reaction rates in highly viscous solvents can be limited by mass transport. In this work, the viscosity of the IL is studied as a function of CO2 pressure. For this, various ILs have been tested to assess the influence of cations or anions. The impact of the change in H2 solubility and the IL viscosity on hydrogenation reactions is validated by kinetic measurements. The model reaction is an iridium-catalysed imine-hydrogenation, which has been successfully applied in the IL/CO2 system by Solinas et al. In the second part of the thesis, a continuous flow set up has been installed and tested for enantioselective hydrogenation. Here the IL is used as a stationary phase supported on silica and immobilising the homogenous rhodium catalyst. The CO2 is the mobile phase delivering the substrate to and extracting the product from the stationary phase. For the optimisation of the process, various catalysts and system parameters such as CO2 flow and system pressure have been examined.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2008

Author dc:creator

• Höfener, Tobias

Contributors dc:contributor

• Leitner, Walter

• info:eu-repo/classification/ddc/540
• Ionische Flüssigkeit
• Kohlendioxid
• Mehrphasensystem
• Heterogene Katalyse
• Homogene Katalyse
• Katalyse
• Hydrierung
• Katalytische Hydrierung
• Chemie
• ionic iquid
• carbon dioxide
• hydrogenation
• multiphase
• catalysis

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

ger

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-113069%22

OAI record oai:identifier

https://publications.rwth-aachen.de/oai2d?verb=GetRecord&metadataPrefix=oai_dc&identifier=oai%3Apublications.rwth-aachen.de%3A50529