Research Subject 2
Development of New Inorganic Membranes
• Membranes
– Ceramic membranes for H2 separation
– Ceramic membranes for CO2 separation
– Studies address mechanism of permeation
• Prediction of permeation properties
Research Subject 2
Studies of Membrane Reactors
Selective
layer
Support
Membrane preparation
Experimental and modeling studies of
membrane reactors
Steam reforming
CH4 + H2O
2CO + 2H2
Ethanol reforming
C2H5OH + 3H2O
6H2 + 2CO2
Applications and New Concepts
Reforming of Natural Gas
• Steam reforming of methane
(750-850 oC)
CH4 + H2O
CO + 3 H2
Feed cleanup Steam reforming
HTS
H 2O
• Water-gas shift
(HTS - 350
CO + H2O
oC,
LTS – 200
CO2 + H2
oC)
• Product purification with
pressure swing adsorption
or cryogenic distillation
Shift
LTS
CH4
Product
H2 purification
CO2 removal
Condensate
P. Hacarlioglu, Y. Gu, S. T. Oyam
Membrane Reactor Studies: Separator
CH4 + H2O
CO + 3 H2
BPR
Quartz wool
Quartz wool
MFC
MFC
MFC
MFC
Quartz chips
Membrane
Gas
Catalyst
bed
Quartz chips
Quartz liner
Temperature
controllerPurge gas
Ar
Ar
H2
3-way
Catalyst bed
chromatograph
Quartz liner
Ar
3-way
MF
Furnace
Control
box Membrane
O2
3-way
Dense alumina tube
Bubble
Flowmeter
Water
Reservoir
Liquid
pump
Dense tube
MFC
BPR
P
4-way
CH4
Condenser
P
Vent
Vent
Combines reaction and separation
Reactor Modeling
For a one-dimensional model
Tube side:
Shell side:
dFi

dL
dF
 Riperm
dL
where

j 1,2,3
F = molar flow
 i , j Ri  Riperm
Riperm  Si a ( Pi shell  Pi tube )
For a two-dimensional model
Tube side:
  2C1i 1 C1i
D1i  2 
r r
 r
Shell side:

C1i

u
0
 1

l

C = concentration
  2C3i 1 C3i 
C3i
 3i D3i  2 

u
 Rkn  0
 3
r r 
l
 r
Pressure Dependence of MSR
CH4 + H2O
CO + 3H2
Pressure (atm)
1
5
10
15
20
Flow rate of CH4
(cm3 (NTP) min-1)
10
50
100
150
200
Fractional conversion of CH4
1.0
Temperature: 873 K
Top: MR
Bottom: PBR
0.8
0.6
1-D model
0.4
0.2
2-D model
0.0
0
5
10
15
Pressure / atm
20
Radial and Axial Profiles of Hydrogen Flow
T = 873 K P = 10 atm
0.00030
Concentration of H2 / mol cm
-3
0.00030
Concentration of H2 / mol cm
-3
T = 873 K P = 1 atm
0.00025
0.00025
0.00020
Membrane
0.00015
0.00010
0.00005
0.00000
dim2.0
1.0
1.5
0.8
en
0.6 gth
sio 1.0
nle
0.4 s len
ss 0.5
0.2 nles
o
rad 0.0 0.0
nsi 0.00030
e
ius
m
di
0.00020
0.00015
0.00010
0.00005
0.00000
2.0
Empty tube
side
Concentration of H2 / mol cm
-3
T = 873 K P = 20 atm
Bed
side
0.00025
0.00020
0.00015
0.00010
0.00005
0.00000
2.0
1.0
dim 1.5
0.8
1.0
0.6
en
h
sio
0.4
ngt
0.5
e
l
nle
s
0.2
les
ss
0.0 0.0
n
o
i
rad
ens
m
ius
i
d
1.0
dim 1.5
0.8
en
0.6
h
sio 1.0
0.4
ngt
0.5
e
nle
l
s
0.2
ss
les
n
0.0
o
rad
i
0.0
ens
ius
m
i
d
When Should a 2-D Model be Used?
Criterion: Order Estimation Parameter
T = 873 K P = 10 atm
0.00030
Concentration of H2 / mol cm
-3
Reaction rate > flow rate
ρR 2
Pe
uCo > dPL
0.00025
0.00020
0.00015
0.00010
0.00005
0.00000
2.0
dim
Gradients expected when:
1.0
1.5
Permeance rate > diffusion rate
PΔP > DΔC/r
1.0
en
sio
nle
ss
r
0.8
0.6
0.4
0.5
ad
0.0
ius
0.2
0.0
dim
s
nle
io
ens
gth
n
s le
Order estimation parameter
2
Pe
uC
PΔP
o
> 0.01
DΔC/r dPL ρR
For our conditions gradients begin when P > 10 atm
R = volumetric rate ρ = density u = flow velocity Co = conc
P = permeance P = pressure r = radius Pe = Peclet num
Operability Level Coefficient (OLC)
Conversion enhancement / %
hydrogen permeation rate (permeance ) (area ) ( ΔP)
= 1/DaPe
OLC =
=
hydrogen formation rate
(rate ) ( volume )
100
MSR, Tsuru et al.
80
60
40
20
Model I
MSR, Tong and Matsumura
MDR, Lee et al.
MSR, Patil et al.
EtOHSR, Lim and Oyama
MSR, Tong and Matsumura
MSR, Hacarlioglu et al.
MDR, Irusta et al.
MeOHSR, Basile et al.
MeOHSR, Lee et al.
k1 (
rI 
Oyama and Lim
PCH 4 PH 2O
PH22.5
-
PH0.25 PCO
)
K1
[1  K CH 4 PCH 4  K CO PCO  K H 2O PH 2O ]2
Model II
Model I
Model II
rII  k1 ( PCH 4 PH 2O -
PCO PH 2
K1
0
0.0
0.2
0.4
0.6
0.8
Operability Level Coefficient / OLC
• Correlation independent of kinetics
• OLC dependent on reaction rates and permeances
3
)
Hollow Fiber Membranes
• High surface area/volume ratio
• Easily processed
• Broad use