Tutorial Modeling of monolith reactors

Diffusion in the washcoat
• For binary eqi-molar counter diffusion of molecules
A and B we write, for the diffusion of A:
D
0.5
⎛ 1 1 ⎞
0.01013⎜
+
M M
⎟
⎝ ⎠ T
P
A B
AB =
0.333 0.333
(( ∑ ) ( ) )
νi
+ ∑νi
A
Bulk diffusion: Fuller correlation
1 1 1
= +
( Dpore) D ( D )
A
AB
Diffusion coefficient in the pore
K
B
A
1.75
( D K ) A
= 48.5 d p
M A
Knudsen diffusion
( D ) = ( D pore )
Effective diffusion coefficient
in the washcoat
T
eff A A
ε
τ
24