CRE is the field that studies the rates and mechanisms of chemical reactions and the design of the reactors in which they take place Lecture 12 Lecture 12 Tuesday 2152011 Multiple Reactions ID: 659205
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Slide1
Chemical Reaction Engineering (CRE) is the field that studies the rates and mechanisms of chemical reactions and the design of the reactors in which they take place.
Lecture
12Slide2
Lecture 12 – Tuesday 2/15/2011Multiple ReactionsSelectivity and Yield
Series Reactions
Complex Reactions
2Slide3
4 Types of Multiple Reactions
Series: A
→ B → C
Parallel: A
→ D,
A → UIndependent: A → B,
C
→ D
Complex: A + B →C + D, A + C → EWith multiple reactors, either molar flow or number of moles must be used (no conversion!)
3Slide4
Instantaneous
Overall
There are two types of selectivity and yield: Instantaneous and Overall.
Selectivity
and
Yield
Selectivity
Yield
4Slide5
To maximize the selectivity of D with respect to U run at high concentration of A and use PFR.
Example
:
Desired
Product
:
Undesired
Product
:
5
Selectivity and YieldSlide6
Gas
Phase
Multiple
Reactions
6Slide7
Flow
Batch
Multiple Reactions Chapter 8
7
A)
Mole Balance of each and every SpeciesSlide8
8
A) Rates:
a)
Rate
law
for each reaction
b
) Net Rates
c
) Relative Rates
Multiple Reactions Chapter 8Slide9
Stoichiometry
:
Gas
Example: A → B → C
(1) A → B k
1
(2) B → C k
2
9
Multiple Reactions Chapter 8
LiquidSlide10
V=V
0
(constant batch)
10
1)
Mole
Balance:
Example:
Batch
Series Reactions
Slide11
L
aws
N
et
rates
2)
Rates:
11
Relative
rates
Example:
Batch
Series Reactions
Slide12
example: A → B → C (1)
A → B
(2) B → C
1)
Mole Balance:
t
t
opt
C
i
A
B
C
12
Example:
Batch
Series Reactions
Slide13
Relative:
Laws:
13
2)
Rates:
Example:
Batch
Series Reactions
Slide14
Species B:
14
Species A:
3) Combine:
Example:
Batch
Series Reactions
Slide15
Using the integrating factor,
at t = 0, C
B
=0
15
Example:
Batch
Series Reactions
Slide16
what is the optimal
?
1)
Mole Balance:
Example:
CSTR
Series Reactions
A
B
C
16Slide17
2)
Rates:
Laws:
Net:
Relative:
17
Example:
CSTR
Series Reactions
A
B
CSlide18
3)
Combine:
18
Example:
CSTR
Series Reactions
A
B
CSlide19
19
Find that gives
maximum concentration of
B
Example:
CSTR
Series Reactions
A
B
CSlide20
20Slide21
End of Lecture 12
21Slide22
Supplementary Slides
22Slide23
Supplementary Material - Blood Coagulation
23Slide24
24Slide25
Notations
25Slide26
Notations
26Slide27
Mole
Balance
27Slide28
Mole
Balance
28Slide29
Mole
Balance
29Slide30
Result
30Slide31
Blood
Coagulation
Many metabolic reactions involve a large number of sequential reactions, such as those that occur in the coagulation of blood.
Cut
→ Blood → Clotting
Figure A. Normal Clot Coagulation of blood
(picture courtesy of:
Mebs
, Venomous and Poisonous Animals,
Medpharm
,
Stugart 2002, Page 305)
31Slide32
Schematic of Blood Coagulation
32Slide33
Cut
A + B
C
D
EF
Clot
33