lecture 10 - university of michiganessen/html/powerpoints/lecture_notes/lec10/cd/lec1… · lecture...
TRANSCRIPT
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 10
Today’s lecture Definition of Selectivety
Instantaneous SD/U = rD/rU
Overall = FD/FU
Semibatch Reactors
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Selectivity in Multiple Reactions
Selectivity Yield
Instantaneous SD/U = rD/rU
Overall ŜD/U = FD/FU
3 Keep CA high and CB low.
Semibatch reactors Semi Batch reactors can be very effective in maximizing
selectivity in liquid phase reactions. The reactant that starts in the reactor is always the limiting
reactant.
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Semibatch reactors
A + B → C + D
Semibatch reactors
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A
B, v0
Initial V
Liquid level and volume increase
Semibatch reactors
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Mass Balance:
Semibatch
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1) Mole balances: Species A:
in – out + gen = acc
Semibatch
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1) Mole balances:
Species B:
Semibatch
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Semibatch 2) Rate Law:
3) Stoichiometry:
4) Parameters: 10
example: A + B → C + D + CO2
A
B, v0 CO2
Semibatch Example
1a) Mole balances:
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1 b) Mass balances:
Semibatch Example
2) Rate Law:
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3) Stoich:
Semibatch Example
4) Parameters: 13
Polymath Screenshots:
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Semi Batch Reactors Three Forms of the Mole Balance applied to Semi Batch Reactors:
1. Molar Basis
2. Concentration Basis
3. Conversion 15
Consider the following elementary reaction: A+B C+D
-rA=kCACB
The combined Mole Balance, Rate Law, and Stoichiometry may be written in terms of number of moles, conversion, and/or concentration:
Conversion Concentration No. of Moles
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Polymath Equations:
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Equilibrium Conversion in Semibatch Reactors with Reversible Reactions
Everything is the same as for the irreversible case, except for the rate law:
Consider the following reaction: A+BC+D
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Equilibrium Conversion in Semibatch Reactors with Reversible Reactions Where:
At equilibrium, then
19 Xe changes with time.
End of Lecture 10
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