Dipl. Ing. Matthias Mayerhofer Technische Universität München ...

46 Experiments
6.2 Catalysts
400 mm
220 mm
195 mm
Figure 19 : Catalyst Bed
217,5 mm
TC1 TC2 TC 3
In this work three types of catalysts were tested. The main interest was drawn to iron based catalysts
for the reasons explained previously. It was interesting though to compare the tar conversion
results to commercially available nickel based and precious metal catalysts.
Catalysts Preparation:
The Iron based catalyst that was used for the tests was manufactured by the University of Bologna,
Italy. The catalyst is supported by Al2O3 (16 wt%) and Mg (68 wt %) was used as a promoter on the
iron (16 wt %). The commercially available nickel based catalysts were prepared by the manufacturer.
Precious metal catalysts were prepared by the supplier too. The amount of catalyst that was
used for all the experiments was 40 mL.
Characterization Techniques
The BET technique (NOVA 4000e surface and pore analyzer, Quantachrome Instruments) was
used to determine the surface area of the catalyst before and after the tests. The results were obtained
through the following procedure; nitrogen at the temperature of liquid nitrogen (77 K) was
used to examine the ability of the adsorption of the molecules on the solid surface. Prior to the procedure
the samples were degassed at 110°C for ½ hour. Sample of ~3,5 g was used.
The determination of the different phase compositions of the Fe catalyst (crystalline constituents)
and the structure of the catalyst before and after the tests was observed by X-Ray diffraction using
Cu-Ra radiation.
Temperature Programmed Reduction (TPR) analyses were carried out with a H2/N2 (10%/90%) gas
mixture. The sample was heated up from room temperature to 900°C with a heating range of
~7°C/min during the whole procedure.
6.3 Experiments
In the first series of experiments the iron based catalysts were tested in different operating conditions.
As a second step a blank test was conducted with an empty catalyst reactor in order to define
the percentage of tar conversion due to thermal cracking. And finally the nickel based and the
precious metal catalysts were tested in comparable operating conditions.
245 mm