Biomedical Engineering Reference
In-Depth Information
TABLE 7.6
Activation Energy and Preexponential Factors for Birch Char
Using the Langmuir
Hinshelwood Rate Constants for CO
2
Gasification
Langmuir
Hinshelwood Rate
Constants (s
2
1
bar
2
1
)
Activation Energy
E
(kJ/mol)
Preexponential Factor
A
(s
2
1
bar
2
1
)
10
5
k
b1
165
1.3
3
k
b2
20.8
0.36
10
7
k
b3
236
3.23
3
Source: Adapted from Barrio and Hustad (2001).
TABLE 7.7
Typical Values for Activation Energy, Preexponential Factor,
and Reaction Order for Char in the Boudouard Reaction
Activation
Energy
E
(kJ/mol)
Reaction
Order,
n
(
Char
Origin
Preexponential
Factor
A
(s
2
1
bar
2
1
)
)
References
2
10
6
s
2
1
bar
2
0.38
Birch
215
3.1
3
0.38
Barrio and
Hustad (2001)
153.5 s
2
1
bar
2
1
Dry
poplar
109.5
1.2
Barrio and
Hustad (2001)
10
8
s
2
1
Cotton
wood
196
4.85
3
0.6
DeGroot and
Shafizadeh
(1984)
10
8
s
2
1
Douglas
fir
221
19.67
0.6
DeGroot and
Shafizadeh
(1984)
3
10
6
s
2
1
Wheat
straw
205.6
5.81
0.59
Risnes et al.
(2001)
3
10
6
s
2
1
Spruce
220
21.16
0.36
Risnes et al.
(2001)
3
-
=
2CO
CO
2
1
C
2
172 kJ
mol
(7.45)
The preceding reaction becomes
thermodynamically feasible when
(P
CO
=
P
CO
2
) is much greater than that of the equilibrium constant of the
Boudouard reaction (Littlewood, 1977).
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