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M. Sc. Valentin Dybbert



Room No.: 01 039 (FMF)

Telephone: +49 (0) 761 203-4733

e-Mail: valentin.dybbert@ac.uni-freiburg.de


Keywords: Heterogeneous catalysis, methanol synthesis


Fig. 1: Thernodyamics of CO2 conversion to methanol at 40 bar.

I’m working on heterogeneous catalysts (Cu/ZnO/ZrO2), which are used for the conversion of carbon dioxide and hydrogen to methanol. Methanol is not only a widely used chemical nowadays, but also one of possible key steps for future energy storage and a possible way to liquid fuels. Nevertheless, for sufficient space-time yields it is necessary to perform the reaction at high temperatures (230 - 250 °C) but since a higher conversion can thermodynamically can only occur at lower temperatures new/improved catalysts are needed for reasonable applications.
The formation of the catalysts starts with a co-precipitation of Cu-,Zn-and ZrO-nitrate with carbonates and hydroxides (see fig. 2), which are subsequently calcinated (300 °C, N2, pre-catalyst) and in-situ reduced to form the active catalyst. I characterize the catalysts properties at all of his stages (precursor, pre-catalyst, active catalyst, post-catalyst) by FTIR, pXRD, physisorption, chemisorption, TGA, DRIFTS, XPS, SEM/EDX, TEM and of course the catalysis itself. For this we use fixed bed reactors at about 40 bar and 200 - 240 °C with gas mixtures of CO2 (25 %) and H2 (75 %), the product stream is then online analyzed by gas chromatography.
Fig. 2: Formation pathway of the catalyst system.
Fig. 3: Catalyst test station with 4 parallel reactors.
We are currently working on quantumchemical calculations concerning the not yet fully understood mechanism of the reaction. Furthermore, we are trying to use the derived knowledge for improving and optimizing the current catalyst system.
Part of my work has recently been submitted for patenting:
E. Frei, V. Dybbert, M. Hill, T. Ludwig, A. Schaadt, H. Hillebrecht, J. Eicher, I. Krossing, patent pending, 2014.


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