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


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


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.

Weitere Angaben

Publikationsform: Veranstaltungsbeitrag (Poster)
Begutachteter Beitrag: Ja
Institutionen der Universität: Fakultäten > Fakultät für Ingenieurwissenschaften
Fakultäten > Fakultät für Ingenieurwissenschaften > Lehrstuhl Chemische Verfahrenstechnik
Fakultäten > Fakultät für Ingenieurwissenschaften > Lehrstuhl Chemische Verfahrenstechnik > Lehrstuhl Chemische Verfahrenstechnik - Univ.-Prof. Dr.-Ing. Andreas Jess
Titel an der UBT entstanden: Ja
Themengebiete aus DDC: 500 Naturwissenschaften und Mathematik > 540 Chemie
600 Technik, Medizin, angewandte Wissenschaften > 600 Technik
600 Technik, Medizin, angewandte Wissenschaften > 620 Ingenieurwissenschaften
600 Technik, Medizin, angewandte Wissenschaften > 660 Chemische Verfahrenstechnik
Eingestellt am: 05 Nov 2015 09:57
Letzte Änderung: 24 Okt 2017 13:31
URI: https://eref.uni-bayreuth.de/id/eprint/21241