Page 335 - Elements of Chemical Reaction Engineering Ebook

306 Multiple Reactions Chap. 6

3. Stoichiometry (no volume change with reaction, u = uo)
a. Reaction rates:

Reaction 1: -rlH = -rli = rlX = rlMe (E6-6.10)

Reaction 2: - r2" = - r2x = r2, = r2Me (E6-6.11)

(E6-6.12)

(E6-6.13)

(E6-6.14)

(E6-6.15)

(E6-6.16)
4. Combining and substituting in terms of the space-time yields

'c= -
V
VO
If we know CM , CH, and Cx, then CM, and C, can be calculated from the reaction
stoichiometry. Consequently, we need only to solve the following three equations:

C
=
- -k 1 C1/2CM-k X HC1I2 (E6-6.17)
2
H
The emergence of dz
user-friendly ODE
c
solvers favors this dCM - =-k 1 M H~'12 (E6-6.18)
approach over dz
fractional
conversion
(E6-6.19)
5. Parameter evaluation:

1
CMo = 5 CHo = 0.0105 Ib moYft3
CXO = 0

We now solve these three equations simultaneously using POLYMATH. The pro-
gram and output in graphical form are shown in Table E6-6.1 and Figure E6-6.1,
respectively. However, I hasten to point out that these equations can be solved ana-
lytically and the solution was given in the first edition of this text.