Solutions to exercises
293
Solution 5.17 – Use of hydrocarbons in SOFCs
1. When operating with hydrogen, we have
2 at the anode
2H 2 + 2O
2−
$ 2H 2 O + 4e
2 at the cathode
O 2 + 4e $ 2O
2−
The overall reaction is O 2 + 2H 2 $ 2H 2 O
2. Chemical oxidation reactions
a. 2 Reforming reaction with water vapor
• For methane
CH 4 + H 2 O m CO + 3H 2
• For an arbitrary hydrocarbon C n H m
C n H m + nH 2 O m nCO + n
m
2
+
^
hH 2
• Applied to butane C 4 H 10
C 4 H 10 + 4H 2 O m 4CO + 9H 2
2 Reforming reaction with carbon dioxide
• For methane
CH 4 + CO 2 m 2CO + 2H 2
• For an arbitrary hydrocarbon C n H m
C n H m + nCO 2 m 2nCO +
m
2 H 2
• Applied to butane C 4 H 10
C 4 H 10 + 4CO 2 m 8CO + 5H 2
2 Cracking reaction
• For methane
CH 4 m C + 2H 2
• For an arbitrary hydrocarbon C n H m
C n H m m nC +
m
2 H 2
• Applied to butane C 4 H 10
C 4 H 10 m 4C + 5H 2