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Unformatted text preview: (9) Species Jump Condition at the Catalytic Surface
We previously showed that the species jump condition for a species A at an interface separating two
phase Α and Γ is given by
t CAs s ΞΒΓ ΞΒΓ w CAs vAs s s (10) CAΒ vAΒ w CAΓ vAΓ ΞΒΓ w RAs For the present problem we will assume the solid/gas interface is stationary so that w=0. Further we will
take Β to be the solid phase and Γ to be the gas phase. Ignoring surface diffusion effects (i.e., vAΒ =0)
and noting that s ΞΒΓ =0 for flat interface, the species jump condition for any species i is:
t ΞΒΓ CiΓ viΓ (11) Ris ΞΒΓ CiΓ viΓ
s If we sum over all species i we get
t i1 s i1 Ris (12) i1 It follows from the site balance that
Cis CT i1 so that
CT (13) 0 t
Recall that we can always write
CiΓ viΓ CiΓ v im xi CiΓ v Ji where v is the molar average velocity, is the molar density of the mixture, and
defined mixture diffusivity. Summing Eq. (14) over all species gives
i1 Thus we have v Ji
i1 v (14)
im is a suitably MultipleSteadyStatesSurfaceReactions.nb ΞΒΓ v Ris 3 (15) i1 Th...
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This document was uploaded on 03/14/2014.
- Winter '14