Page 61 - Modeling of Chemical Kinetics and Reactor Design

Reaction Mechanisms and Rate Expressions 31

kC x 3 ≅ k C C R (1-133)
−
3
3
x 1
and
C = C + C + C
T x 1 x 2 x 3 (1-134)

Rearranging Equations 1-132 and 1-133 in terms of C and C
x 2 x 3
and substituting them in Equation 1-134 gives

C = C + k −2 • k −3 CC + k −3 CC
T x 1 x 1 R x 1 R
k 2 k 3 k 3
Therefore,

C = C T
x 1 1+ KC (1-135)
T R
where

 k k k 
K = −2 • −3 + −3
 k 2 k 3 k 
T   (1-136)
3
Substituting Equation 1-136 into Equation 1-131 to eliminate C , yields
x 1

1
− ( r ) = (kC T )C A (1-137)
A net
1 + KC
T R
or

4
− ( r ) = KC A
A net (1-138)
1 + KC
T R
If the reverse step in adsorption is not ignored, then

5
4
− ( r ) = KC A − K C R
A net (1-139)
1 +KC R
T