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Unformatted text preview: ces) for B and C:
B: CB= CA0 XA,1 C: CC= CA0 XA,2 A: CA=
CA= Everything else remains unchanged – we now simply have one more quantity to keep
track of, i.e. the different Xji! ChE
ChE 400 - Reactive Process Engineering Series Reactions: Selectivity L11-14
L11- A -> B -> C
Very common: partial vs total oxidation reactions
(Almost) all oxidation reactions follow a sequence of successively “deeper” oxidation.
Example: Ethane oxidation
C2H6 + ½ O2 -> C2H4 + H2O (oxidative dehydrogenation)
C2H4 + O2 -> 2 CO + 2 H2 (syngas formation)
CO + H2 + O2 -> CO2 + H2O
(combustion) Let’s assume a PFR for A -> B -> C, with 1st order kinetics:
rA = , rB = = Plugging this into the PFR design equation, we get: C A (τ ) =
CC (τ ) = CB (τ ) = Check the derivation in the
textbook (p. 160ff)!
You should be able to derive
this yourself. So, what does this look like? ChE
ChE 400 - Reactive Process Engineering Series Reactions: CSTR L11-15
L11- What about the same series reaction in...
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- Fall '13