Olefinmetathese von Ölsäuremethylester in Mehrphasensystemen aus ionischen Flüssigkeiten und überkritischem Kohlendioxid
- Olefin metathesis of oleic acid methyl ester in multi-phase systems from ionic liquids and supercritical carbon dioxide
Hermanns, Thomas; Leitner, Walter (Thesis advisor); Klankermayer, Jürgen (Thesis advisor)
Aachen : Publikationsserver der RWTH Aachen University (2016)
Dissertation / PhD Thesis
Aachen, Techn. Hochsch., Diss., 2015
The use of biogenic resources as a future feedstock supply is of increasing importance. Fats and oils derived from sustainable sources provide unsaturated fats and thus a possibility for the production of various intermediates and end products for the chemical industry.In this work a reaction system for the transformation of unsaturated fatty acid esters via homogeneously catalysed olefin metathesis is investigated. Commercially available methyl oleate serves as a model compound. The separation of the catalyst from the products is achieved by using multi-phase systems, in which the catalyst is immobilized in a polar, non-volatile phase and the substrate is dissolved in a non-polar, volatile phase. For the catalytic phase ionic liquids (IL) were used, while the substrate and products were transported in an out with supercritical carbon dioxid (scCO2). It was shown, that with a set of commercially available components, i.e. alkyl imdizalolium-IL and Hoveyda-Grubbs’ catalyst, the self-metathesis of methyl oleate is catalyzed to full equilibrium conversions (50 %) within 30 min. The cross-metathesis with ethylene (ethenolysis) was investigated comparing the commercial catalyst with a ruthenium catalyst bearing an indenylidene ligand, which was provided by a cooperation partner. This indenylidene catalyst showed high activity (80 % conversion) and high selectivity (95 %) towards the ethenolysis products. With a mixture of both catalysts, it was possible to choose between either the self- or the cross metathesis and even switch the reaction as desired. Multiphase systems, like the one introduced in this work, facilitate a continuous flow application. Within this work a high-pressure rig was planned and built. The aforementioned reaction system was transferred into continuous flow operation and investigated. Furthermore a continuous in-stream separation step was realized within the high-pressure rig, thus enabling product separation without the necessity to decompress the scCO2 solvent. It was shown the stationary IL-phase as well as the temperature separation step have significant influence on the product distribution within the product stream. Depending on the reaction control the ratio of self-metathesis product can be increased from 1:1 to 8:1, enabling the possibility of subsequent reactions with one of the products, while the other could be recycled into the stream.