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Perrhenate-containing ionic liquids as catalysts in olefin epoxidation: activity, kinetics and reaction engineering

Title data

Schäffer, Johannes ; Korth, Wolfgang ; Jess, Andreas ; Wilhelm, M. ; Cokoja, Mirza:
Perrhenate-containing ionic liquids as catalysts in olefin epoxidation: activity, kinetics and reaction engineering.
Event: ESCRE 2015 - European Symposium on Chemical Reaction Engineering , 27.-30.10.2015 , Fürstenfeldbruck, Deutschland.
(Conference item: Conference , Poster )

Abstract in another language

As opposed to inorganic perrhenate salts, imidazolium-based perrhenate-containing ionic liquids (ILs) have been demonstrated to be active as catalysts for olefin epoxidation with hydrogen peroxide as oxidant and cyclooctene as olefin [1]. Depending on the structure of the IL cations, large differences in the rate of formation of epoxide were observed. Solubility effects are investigated as a possible key to understanding these differences in catalytic activity. Also, selectivity of the ILs toward undesired H2O2 decomposition is examined in this respect. In view of a technical application, the ILs are tested in propene epoxidation to propylene oxide (annual production: approx. 5 Mt) and both a batch and continuous reaction system are presented.
Factors influencing catalytic activity
For this survey, three ILs of different activity were selected and their solubility in H2O, 50 % H2O2/H2O and cyclooctene was determined at room temperature and reaction temperature (70°C). All three ILs were not soluble in cyclooctene but showed low solubility in water which was increased markedly, yet at different extent, by the addition of H2O2. Moreover, when analysing the cyclooctene content in the aqueous phase in the presence of ILs, we found that the ILs acted as solubiliser of organic substrate into the aqueous phase. The results suggest that the epoxidation reaction takes place in the aqueous phase. However, the difference in catalytic activity cannot be explained solely by the solubility data.
As a further aspect, kinetics of decomposition of H2O2 to water and O2 as a competing reaction to the desired epoxidation was investigated at reaction temperature by monitoring the O2 evolution. For the three ILs, great differences in activity toward H2O2 decomposition were found, which in combination with solubility data reasonably explain the overall trend in catalytic activity.
Kinetic experiments and reaction engineering
Preliminary tests have shown catalytic activity of the perrhenate-containing ILs in propene epoxidation. For a thorough investigation, a batch reactor setup was chosen for catalytic testing as is also proposed in the literature [2]. Kinetic experiments are being performed at varying temperature and propene partial pressure. Following recent trends to utilise hydrogen peroxide in the gas phase [3] and with the particular properties of ILs in mind, e.g. negligible vapour pressure, immobilization of the ILs onto a commercial support and the potential of their application in a fixed-bed reactor is also examined.
[1] I. I. E. Markovits et al., Chem. Eur. J. 2013, 19, 5972.
[2] M. G. Clerici et al., J. Catal. 1991, 129, 159-167.
[3] E. Klemm et al., Ind. Eng. Chem. Res. 2008, 47, 2086-2090.

Further data

Item Type: Conference item (Poster)
Refereed: Yes
Institutions of the University: Faculties > Faculty of Engineering Science
Faculties > Faculty of Engineering Science > Chair Chemical Engineering
Faculties > Faculty of Engineering Science > Chair Chemical Engineering > Chair Chemical Engineering - Univ.-Prof. Dr.-Ing. Andreas Jess
Result of work at the UBT: Yes
DDC Subjects: 500 Science > 540 Chemistry
600 Technology, medicine, applied sciences > 600 Technology
600 Technology, medicine, applied sciences > 620 Engineering
600 Technology, medicine, applied sciences > 660 Chemical engineering
Date Deposited: 05 Nov 2015 09:57
Last Modified: 09 Nov 2022 13:25