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Lecture 9 Thursday 1/31/08 Membrane Reactors: Used for Thermodynamically Limited Reactions
Balances in Terms of Molar Flow Rates
Block 1: Mole Balances Balance Equation on Every Species Block 2: Rate Laws Relative Rates Transport Laws Block 3: Stoichiometry Block 4: Combine
Multiple Reactions: Selectivety and Yield
Membrane Reactors
Dehydrogenation Reaction:
C3H8 ↔ H2 + C3H6 A ↔ B + C
Thermodynamically Limited:
W = ρbV
ρb = (1-ϕ)ρC
1) Mole Balance: A: In – out + generation = 0
RB = A:
B: In – out – out membrane + generation = 0
B:
reactor of volume
sides through B of moles
000
VrFF AVVAVA
AA r
dV
dF
XCXC
T T
endothermicexothermic
A,B,C
sweep
FA0
B
B
A,C stay behind since they are too big
H2 H2CBS
0
VrVRFF BBVVBVB
)( BBB Rr
dV
dF
)(`BSBCB CCkW DL
DLa
D
4
lumereactor vo
area surface membrane
4
2
BSBCBB CCakaWR ` BSBCB CCkR
Neglected most of the time
Parameters: CTO = 0.2, FA0= 5, k = 4, KC = 0.0004, kC = 8
1)
2)
3)
4)
Relative rates:
5)
6)
7) (isothermal, isobaric)
8)
9)
10)
AA r
dV
dF
BBB Rr
dV
dF
CC r
dV
dF
C
CBAA K
CCCkr
111CBA rrr
T
ATA F
FCC 0
T
BTB F
FCC 0
T
CTC F
FCC 0
CBAT FFFF
CABA rrrr ,
BCB CkR