333
solid-carbon in the spent catalyst may also contribute partially to the decrease in
CO 2 conversion as observed above.
3.7 XPS Analysis of the Spent Catalyst
Different types of carbon have been detected during the DRM reaction over supported nickel catalysts [11, 13, 14]. These carbonaceous species are classified as
carbidic carbon, graphitic carbon and carbon associated with oxygenated species.
Furthermore, these carbonaceous species are identified by the binding energy of C 1s
in the XPS as shown in Fig. 15. The presence of the different type of carbonaceous
species appears to depend on the temperature and presence of oxygen. With
increasing temperature and with oxygen present in the feed, the carbon associated
with oxygenated species, such as alcohol or ether groups, significantly decrease.
This is evident when one compares Fig. 15a with c, or Fig. 15a with b, or Fig. 15c
with d. Thus, operating conditions such as a temperature of 750 °C rather than
600 °C and addition of oxygen help reduce carbon formation.
4 Catalyst Improvement Strategies to Alleviate Coking
The catalyst composition itself can be tuned to attain coking resistance. In what follows, we present observations on the design of catalyst to reduce carbon deposition on it.
4.1 Adding Basic Component to Ni Catalyst System May
Reduce Coke Deposition
Structure and composition of catalyst play an important role in determining the
amount of carbon formed on the catalysts during DRM and associated reactions. An
ultrasound-assisted co-precipitation method showed that increasing Ni content in
Table 5 CHN/O and TGA analysis for elemental carbon on 10% Ni/MgAl 2 O 4 during ODRM at
600 and 750 °C after 4 h TOS
Reaction
condition
Reaction
temperature (°C)
% Carbon deposited on the
spent catalyst by CHN/O
TGA analysis (total %
weight loss)
2.6ODRM
5.0ODRM
7.5ODRM
600
51.2
49.3
29.4
57.4
Not determined
Not determined
2.6ODRM
5.0ODRM
7.5ODRM
750
1.4
0.6
0.6
10.1
Not determined
Not determined
Flue Gas Treatment via Dry Reforming of Methane
solid-carbon in the spent catalyst may also contribute partially to the decrease in
CO 2 conversion as observed above.
3.7 XPS Analysis of the Spent Catalyst
Different types of carbon have been detected during the DRM reaction over supported nickel catalysts [11, 13, 14]. These carbonaceous species are classified as
carbidic carbon, graphitic carbon and carbon associated with oxygenated species.
Furthermore, these carbonaceous species are identified by the binding energy of C 1s
in the XPS as shown in Fig. 15. The presence of the different type of carbonaceous
species appears to depend on the temperature and presence of oxygen. With
increasing temperature and with oxygen present in the feed, the carbon associated
with oxygenated species, such as alcohol or ether groups, significantly decrease.
This is evident when one compares Fig. 15a with c, or Fig. 15a with b, or Fig. 15c
with d. Thus, operating conditions such as a temperature of 750 °C rather than
600 °C and addition of oxygen help reduce carbon formation.
4 Catalyst Improvement Strategies to Alleviate Coking
The catalyst composition itself can be tuned to attain coking resistance. In what follows, we present observations on the design of catalyst to reduce carbon deposition on it.
4.1 Adding Basic Component to Ni Catalyst System May
Reduce Coke Deposition
Structure and composition of catalyst play an important role in determining the
amount of carbon formed on the catalysts during DRM and associated reactions. An
ultrasound-assisted co-precipitation method showed that increasing Ni content in
Table 5 CHN/O and TGA analysis for elemental carbon on 10% Ni/MgAl 2 O 4 during ODRM at
600 and 750 °C after 4 h TOS
Reaction
condition
Reaction
temperature (°C)
% Carbon deposited on the
spent catalyst by CHN/O
TGA analysis (total %
weight loss)
2.6ODRM
5.0ODRM
7.5ODRM
600
51.2
49.3
29.4
57.4
Not determined
Not determined
2.6ODRM
5.0ODRM
7.5ODRM
750
1.4
0.6
0.6
10.1
Not determined
Not determined
Flue Gas Treatment via Dry Reforming of Methane