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

56 Results and Discussion
Wet gas composition Vol (%)
Figure 29: Nickel catalyst-Wet gas Composition-SV dependence
The precious metal catalyst also had higher tar conversion than the iron based catalyst but lower
than the nickel one, the gas composition can be seen in Figure 30. CH4 is low, not as low as with
as with the nickel catalyst, but it evident that the hydrocarbons are significantly converted. Steam is
~30%, much lower than the value in the gas composition before the catalyst which indicates high
steam reforming action. The CO2 and CO values are lower for this catalyst, which indicates a not so
high activity of the equations. H2 is ~35%, as it is for the iron based catalyst. The best results are
obtained for the lowest space velocity, but the different results between the various operating conditions
are not significant.
Wet gas composition (%)
60
50
40
30
20
10
0
40
35
30
25
20
15
10
5
0
6500 10000 12500 14500
SV (1/h)
4500 6500 10000
SV (1/h)
Figure30: Precious metal catalyst-Wet gas composition-SV dependence
It is interesting at this point to mention the behavior of the precious metal catalysts regarding CH4
conversion. In Figure 31, it can be seen that the product gas started running through the catalyst
bed, the methane of the gas composition was zero for a short amount of time. But then it started
rising, which in the first place could probably be interpreted as deactivation of the catalyst. Howev-
CH₄
CO
CO₂
H₂
H₂O
CH₄
CO
CO₂
H₂
H₂O