Lecture 12 Tuesday 2/12/08 Multiple Reactions Selectivety and Yield Series Reactions Complex Reactions
Department of Chemical Engineering, University of Michigan, Ann Arbor
2 HSF, 04/22/23
Many metabolic reactions involve a large number of sequential reactions, such as those that occur in the coagulation of blood.
Cut → Blood → Clotting
Blood Coagulation
Figure A. Normal Clot Coagulation of blood
(picture courtesy of: Mebs, Venomous and Poisonous Animals, Medpharm, Stugart 2002, Page 305)
Department of Chemical Engineering, University of Michigan, Ann Arbor
3 HSF, 04/22/23
Schematic of Blood Coagulation
Department of Chemical Engineering, University of Michigan, Ann Arbor
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Cut
A + B
C
D
E
F
Clot
Department of Chemical Engineering, University of Michigan, Ann Arbor
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MODEL EQUATIONS:
Department of Chemical Engineering, University of Michigan, Ann Arbor
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MODEL EQUATIONS:
Department of Chemical Engineering, University of Michigan, Ann Arbor
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NOTATIONS
Department of Chemical Engineering, University of Michigan, Ann Arbor
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NOTATIONS
Department of Chemical Engineering, University of Michigan, Ann Arbor
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MOLE BALANCE
Department of Chemical Engineering, University of Michigan, Ann Arbor
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MOLE BALANCE
Department of Chemical Engineering, University of Michigan, Ann Arbor
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MOLE BALANCE
Department of Chemical Engineering, University of Michigan, Ann Arbor
12 HSF, 04/22/23
RESULTS
Multiple Reactionsexample: A → B → C
(1) A → B
(2) B → C
1) Mole balances:
2) Rates: rate laws:
relative rates:
3) Combine:
CC
BB
AA r
dtdCr
dtdCr
dtdC
BB
AA
CkrCkr
22
11
11
11
2211 CBBA rrrr
BAAC
tktkAB
Btk
ABB
BABBB
tkAAAA
A
CCCC
eekk
CkC
C teCkCkdt
dC
CkCkrrdt
dC
eCCCkrdt
dC
0
12
01
012
2121
01
21
1
1
0 ,0at
When is CB the highest?
12
1
2
1
2
2112
01
ln
0
12
21
kkkk
tkke
ekekkk
Ckdt
dC
tkk
tktkAB
Example: CSTR multiple reactions A → B → C
what is the optimal ?
1) Mole Balance:
0000
00
0
0
000
0
BB
BB
AAA
AAA
AAA
rCVrCV
rCCVrVCVC
VrFF
2) Rates: laws: net:
relative:
3) Combine:
BB
AA
CkrCkr
22
11
BABBB
AAA
CkCkrrrCkrr
2121
11 0
11
112211 CBBA rrrr
21max
12
01
2
1
21
1
0
10
111
1
01
0
kk
kkCkC
kCkC
CkCkCk
CC
CkCC
AB
AB
BAB
AA
AAA
0d
dCB
Example: Liquid phase PFR
A + 2B → C (1)
2A + 3C → D (2)
1) Mole balances:
2) Rates: laws:
net:
relative:
3) Stoich:
overall selectivity:
parameters:
DD
CC
BB
AA r
dVdFr
dVdFr
dVdFr
dVdF
3222
211 CACCBAAA CCkrCCkr
DDCCC
BBAAA
rrrrrrrrrr
221
121
CDCADCA
ABACCBA
rrrrrrr
rrrrrrr
2222222
1111111
31
32
132
2 121
15 ,102 ,2 ,250 ,100
21
000
AA
BA
kkCCVV
00000
V VVFC
VFC
VFC
VFC D
DC
CB
BA
A
0
0 0000001.0
~
A
AA
D
C
D
C
FFFX
FF
FFS