M&C CG-2 - Catalyst Material Selection; Catalyst Temperature Selection

12 CG-2 | 1.04.00 www.mc-techgroup.com
8.1 SELECTION OF THE APPROPRIATE CATALYST MATERIAL
For the conversion, as noted preliminary, two catalyst materials are available.
As a standard material, a carbon-molybdenum mixture type C is used as catalyst. The carbon support-
ing material guarantees optimal contact between the gas to be converted and the surface of the catalyst
combined with a simultaneously low flow resistance.
The catalyst type C, operated within a flow range of 30 … 60 Nl/h, is able to convert NO
2
concentrations
up to 200 ppm to NO, achieving conversion ratios of >95 %. If necessary, the operating temperature of
the converter has to be raised within the admissible range.
NOTE!
For catalyst type C no oxygen in the sample gas as well as in the test gas is
necessary. A calibration with test gas NO
2
in N
2
is possible.
Alternatively, to type C, a cartridge with metal filling type SS is available. It is possible to convert NO
2
concentrations of up to 2000 ppm into NO. A temperature adaption might also be necessary.
Figure 3 Notch to differentiate the two cartridge types
NOTE!
For catalyst type SS, oxygen in the sample gas as well as in the test gas
(> 1 vol% O
2
) is necessary. A calibration with NO
2
in N
2
is not possible.
8.2 SELECTION OF THE APPROPRIATE CATALYST TEMPERATURE
The converter with carbon-molybdenum cartridge filling is pre-adjusted to 350 °C [662 °F] in the factory.
In case of a metallic cartridge filling, the converter temperature is adjusted to 660 °C [1220 °F]. The
catalyst temperature can be adjusted continuously using the temperature controller on the front of the
converter (see chapter 18.2).
NOTE!
Depending on the gas composition and the flow temperature can be
adjusted and optimised within a certain level:
320 to 380°C [608 to 716 °F], type C respectively
620 to 680°C [1148 to 1256 °F]. type SS.
Type SS