co2 plasticization in polyimide membranes: coupling of … · 2018-08-06 · co 2 plasticization in...
TRANSCRIPT
![Page 1: CO2 Plasticization in Polyimide Membranes: Coupling of … · 2018-08-06 · CO 2 Plasticization in Polyimide Membranes: Coupling of Permeation, Sorption, and Polymer Swelling John](https://reader034.vdocuments.site/reader034/viewer/2022042712/5f8fd789afda5e3cb2382463/html5/thumbnails/1.jpg)
CO2 Plasticization in Polyimide Membranes: Coupling of Permeation,
Sorption, and Polymer Swelling
John D. Wind, Stephen M. Sirard, Donald R. Paul, Peter F. Green, Keith P. Johnston, and William J. Koros*
The University of Texas at Austin and *The Georgia Institute of Technology
C2
C1
!
AIChE National MeetingSan Francisco 2003
![Page 2: CO2 Plasticization in Polyimide Membranes: Coupling of … · 2018-08-06 · CO 2 Plasticization in Polyimide Membranes: Coupling of Permeation, Sorption, and Polymer Swelling John](https://reader034.vdocuments.site/reader034/viewer/2022042712/5f8fd789afda5e3cb2382463/html5/thumbnails/2.jpg)
Overview• Motivation
u Membrane limitations• Mixed gas performance • Materials and crosslinking scheme• Decoupling of physical and chemical changes with heat
treatmentu Free volume vs. physical agingu Permeationu Sorptionu Swelling by in-situ ellipsometryu Long-term relaxations: polymer swelling and CO2 diffusion
• Conclusions and Future Work
C2
C1
!
![Page 3: CO2 Plasticization in Polyimide Membranes: Coupling of … · 2018-08-06 · CO 2 Plasticization in Polyimide Membranes: Coupling of Permeation, Sorption, and Polymer Swelling John](https://reader034.vdocuments.site/reader034/viewer/2022042712/5f8fd789afda5e3cb2382463/html5/thumbnails/3.jpg)
• Remove CO2 from natural gas mixtures ⇒ maximize gas heating value and minimize corrosion
• $1.3 Trillion gas off-spec in U.S.‡
Motivation for Project
‡ Meyer, H.S., Volume and Distribution of Subquality Natural Gas in the United States, 2000, Gas Research Institute.
75% CH43% C2H63% C3-C51% C6+5-20% CO2Water Sat’d750-4000 psia
< 2% CO210°F Dew Point
Permeate to FlareOr Sequestration50-1500 psia Product
To Pipeline
Heat Exchanger
• Goal: inhibit plasticization: permselectivity losses from excessive polymer chain segmental motion CH4 loss ($$)
• Polyimides Superior transport properties relative to cellulose acetate Need to be more robust
![Page 4: CO2 Plasticization in Polyimide Membranes: Coupling of … · 2018-08-06 · CO 2 Plasticization in Polyimide Membranes: Coupling of Permeation, Sorption, and Polymer Swelling John](https://reader034.vdocuments.site/reader034/viewer/2022042712/5f8fd789afda5e3cb2382463/html5/thumbnails/4.jpg)
Highly Permeable and Stable Materials in Mixed Gas
Adapted from L. Robeson,J. Membr. Sci, 1991
1
10
100
1000
0.1 1 10 100 1000
CO2 Permeability (Barrers)
Sele
ctiv
ity C
O2/C
H4
Robeson's 1991 Upper Limit
Commercially Attractive Region
50/50 CO2/CH435°C, 25 atm
Lit. Datapure gas, < 10 atm
Cellulose Acetate Matrimid®
(50/50 mixed gas25 atm)
J. Membr. Sci, 2003, in press.
![Page 5: CO2 Plasticization in Polyimide Membranes: Coupling of … · 2018-08-06 · CO 2 Plasticization in Polyimide Membranes: Coupling of Permeation, Sorption, and Polymer Swelling John](https://reader034.vdocuments.site/reader034/viewer/2022042712/5f8fd789afda5e3cb2382463/html5/thumbnails/5.jpg)
Polymer Structure
Crosslinking Agents
Butylene Glycol(BG)
OHOH
CF3 CF3O
O O
O
N
COOH
CF3 CF3
O
O
O
O
CH3 CH3
CH3
O N N N
2 1
CH2OHHOCH2
1,4-cyclohexanedimethanol(CHDM)
![Page 6: CO2 Plasticization in Polyimide Membranes: Coupling of … · 2018-08-06 · CO 2 Plasticization in Polyimide Membranes: Coupling of Permeation, Sorption, and Polymer Swelling John](https://reader034.vdocuments.site/reader034/viewer/2022042712/5f8fd789afda5e3cb2382463/html5/thumbnails/6.jpg)
Covalent Crosslinking Mechanism
Solid State(vacuum)
(2) TransesterificationO
HO--RO
+O
O------R-------OO
HO--R--OH2 Δ
Tg ~ 360 °C
In Solution
(1) MonoesterificationOHO HO--R
HO--R--OH+ + H2O
O
H+
Macromolecules, 2003, 36, 1882-1886.
Generalized mechanism1. Simpler transition to hollow fibers2. Allows for spectroscopic characterization along
reaction pathway
![Page 7: CO2 Plasticization in Polyimide Membranes: Coupling of … · 2018-08-06 · CO 2 Plasticization in Polyimide Membranes: Coupling of Permeation, Sorption, and Polymer Swelling John](https://reader034.vdocuments.site/reader034/viewer/2022042712/5f8fd789afda5e3cb2382463/html5/thumbnails/7.jpg)
Heat Treatment:Physical Aging and Crosslinking
Annealing and Crosslinking: significant changes to polymer structure below Tg (~ 360°C)
Polymer6FDA-DAM:DABA 2:1
0
40
80
120
160
100 150 200 250 300
CO
2 Per
mea
bilit
y (B
arre
rs)
Annealing Temperature (oC)
Free Acid Groups
CHDM
BG
Macromolecules, 2003, 36, 1882-1886.
![Page 8: CO2 Plasticization in Polyimide Membranes: Coupling of … · 2018-08-06 · CO 2 Plasticization in Polyimide Membranes: Coupling of Permeation, Sorption, and Polymer Swelling John](https://reader034.vdocuments.site/reader034/viewer/2022042712/5f8fd789afda5e3cb2382463/html5/thumbnails/8.jpg)
0
50
100
150
200
250
0 10 20 30 40 50 60
CO
2 Per
mea
bilit
y (B
arre
rs)
CO2 Feed Pressure (atm)
CO2 Permeation Isotherms6FDA-DAM:DABA 2:1
Free Acid Groups130°C
295°C
Annealing temps = better plasticization resistance
Macromolecules, 2003, 36, 6433-6441.
220°C
0
20
40
60
80
100
0 10 20 30 40 50 60 70
CO
2 Per
mea
bilit
y (B
arre
rs)
CO2 Feed Pressure (atm)
CHDM monoester
100°C
295°C
220°C
Crosslinking increases permeability
![Page 9: CO2 Plasticization in Polyimide Membranes: Coupling of … · 2018-08-06 · CO 2 Plasticization in Polyimide Membranes: Coupling of Permeation, Sorption, and Polymer Swelling John](https://reader034.vdocuments.site/reader034/viewer/2022042712/5f8fd789afda5e3cb2382463/html5/thumbnails/9.jpg)
CHDM Monoester
0
20
40
60
80
100
120
0 10 20 30 40 50C
O2 C
once
ntra
tion
(cm
3 (STP
)/cm
3 pol
ymer
)CO
2 Pressure (atm)
100°C
295°C
Free Volume Created
CO2 Sorption Isotherms
Free Acid Groups
6FDA-DAM:DABA 2:1 at 35°C
0
50
100
150
200
0 10 20 30 40 50
CO
2 Con
cent
ratio
n
(cm
3(ST
P)/c
m3 p
olym
er)
Pressure (atm)
100°C
295°C
Physical Aging
Macromolecules, 2003, 36, 6433-6441.
Sorption modes affected in different ways
![Page 10: CO2 Plasticization in Polyimide Membranes: Coupling of … · 2018-08-06 · CO 2 Plasticization in Polyimide Membranes: Coupling of Permeation, Sorption, and Polymer Swelling John](https://reader034.vdocuments.site/reader034/viewer/2022042712/5f8fd789afda5e3cb2382463/html5/thumbnails/10.jpg)
Pg
PMMA,35°C
Basic Principle:Reflection of light causes a changein polarization state of light
Extract thickness and refractive index, independently
Input-Optical model-Known parameters
Output:- Dilation, sorption-Tg, Pg (Sirard et al, Macromolecules, 2002)
70o
Sample
P
CO2cylinder
Spectroscopic Ellipsometry
![Page 11: CO2 Plasticization in Polyimide Membranes: Coupling of … · 2018-08-06 · CO 2 Plasticization in Polyimide Membranes: Coupling of Permeation, Sorption, and Polymer Swelling John](https://reader034.vdocuments.site/reader034/viewer/2022042712/5f8fd789afda5e3cb2382463/html5/thumbnails/11.jpg)
0
5
10
15
20
25
0 20 40 60 80 100
Swel
ling
(%)
Pressure (atm)
Swelling and Plasticization
Film Thickness ~ 120 nm hollow fiber skin thickness
plasticization pressures
Increased ThermalTreatment (130°C, 220°C, 295°C
Sorption
Desorption
Similar results for free acid polymer
Polymer6FDA-DAM:DABA 2:1CHDM Monoester
Macromolecules, 2003, 36, 6433-6441.
![Page 12: CO2 Plasticization in Polyimide Membranes: Coupling of … · 2018-08-06 · CO 2 Plasticization in Polyimide Membranes: Coupling of Permeation, Sorption, and Polymer Swelling John](https://reader034.vdocuments.site/reader034/viewer/2022042712/5f8fd789afda5e3cb2382463/html5/thumbnails/12.jpg)
Long-Term Stability: CHDM Monoester
0
3
6
9
12
15
0 5 10 15 20 25 30
Swel
ling
(%)
Time (h)
100°C220°C
295°C
Swelling40 atm CO2 @ 35°C
Permeability
1.0
1.5
2.0
2.5
3.0
3.5
0 5 10 15 20
P t/P0
Time (days)
100°C
220°C295°C
Correlation between swelling and permeability KineticsAmplitude of instability
Macromolecules, 2003, 36, 6442-6448.
![Page 13: CO2 Plasticization in Polyimide Membranes: Coupling of … · 2018-08-06 · CO 2 Plasticization in Polyimide Membranes: Coupling of Permeation, Sorption, and Polymer Swelling John](https://reader034.vdocuments.site/reader034/viewer/2022042712/5f8fd789afda5e3cb2382463/html5/thumbnails/13.jpg)
100
110
120
130
0 20 40 60 80
CO
2 Con
cent
ratio
n
cm3 (S
TP)/c
m3 p
olym
er
Time (h)
CO2 Sorption Kinetics: CHDM Crosslinking
• Sorption does not describe permeation stability well at all!• Long-term swelling without much sorption (Bohning and Springer
Polymer, 1998)
100°C
295°C
Permeability Increases at 48 hr.230 %
7 %
40 atm CO2 @ 35°C
![Page 14: CO2 Plasticization in Polyimide Membranes: Coupling of … · 2018-08-06 · CO 2 Plasticization in Polyimide Membranes: Coupling of Permeation, Sorption, and Polymer Swelling John](https://reader034.vdocuments.site/reader034/viewer/2022042712/5f8fd789afda5e3cb2382463/html5/thumbnails/14.jpg)
Summary: Crosslinking and Plasticization
Temperature (°C)
kD (cm3 (STP)/ (cm3 atm)
CH’
(cm3(STP)/ cm3)
100 1.8 31 295 0.81 60
Sorption
AAA
AHAADA p
pbbCkC ⎟⎟
⎠
⎞⎜⎜⎝
⎛
++=1
'
Henry’s law
Langmuir+
Dual Mode Sorption:
Decreased Chain Mobility and Swelling
Increased Free Volume and Permeability
Swelling and PermeationThermal
Treatment (°C) Plasticization
Pressure (atm)
Concentration cm3(STP)/cm3
polymer
CO2 Partial Molar Volume
(cm3/mole) 130 Free Acid 12 38 27
220 Free Acid 30 73 28
100 CHDM 12 33 28
220 CHDM 36 64 31
pT
CO Chh
,
0400,222
⎥⎥⎥⎥
⎦
⎤
⎢⎢⎢⎢
⎣
⎡
∂
⎟⎠⎞
⎜⎝⎛∂
=υ
Plasticization pressure in permeation correlates with CO2 sorbed partial molar volumeSupported by other data in literature (Bohning and Springer, Polymer, 1998)
![Page 15: CO2 Plasticization in Polyimide Membranes: Coupling of … · 2018-08-06 · CO 2 Plasticization in Polyimide Membranes: Coupling of Permeation, Sorption, and Polymer Swelling John](https://reader034.vdocuments.site/reader034/viewer/2022042712/5f8fd789afda5e3cb2382463/html5/thumbnails/15.jpg)
Conclusions and Recommendations• Covalent crosslinking can stabilize membranes against
plasticization• Thermal treatment is significant in determining transport
properties and long-term stability• Controlling swelling is key to controlling plasticization• Need to assess the long-term stability in presence of
multicomponent high pressure natural gas streams• Need to understand effect of crosslinking on diffusion
coefficients of various penetrants
n-butanepropane toluene
![Page 16: CO2 Plasticization in Polyimide Membranes: Coupling of … · 2018-08-06 · CO 2 Plasticization in Polyimide Membranes: Coupling of Permeation, Sorption, and Polymer Swelling John](https://reader034.vdocuments.site/reader034/viewer/2022042712/5f8fd789afda5e3cb2382463/html5/thumbnails/16.jpg)
Fundingu U.S. Department of Energyu National Science Foundation
Collaborationsu Dr. Ryan Burnsu Joseph Pham
Acknowledgements
![Page 17: CO2 Plasticization in Polyimide Membranes: Coupling of … · 2018-08-06 · CO 2 Plasticization in Polyimide Membranes: Coupling of Permeation, Sorption, and Polymer Swelling John](https://reader034.vdocuments.site/reader034/viewer/2022042712/5f8fd789afda5e3cb2382463/html5/thumbnails/17.jpg)
Relaxation Times
⎟⎟⎠
⎞⎜⎜⎝
⎛−−=
−
−
∞ R0
0
τexp1 t
YYYY
Rt φ
Relaxation-controlled Permeation, Swelling , and Sorption all follow same functional form:
Annealing Temperature
(°C)
Permeation (h)
Swelling (h)
Sorption (h)
100 16 0.57 6.8 295 47 5.3 5.8
Crosslinking slows relaxations
Thin film swelling fast relaxationsimportant for practical membranes!
CHDM Monoester (τ values)
![Page 18: CO2 Plasticization in Polyimide Membranes: Coupling of … · 2018-08-06 · CO 2 Plasticization in Polyimide Membranes: Coupling of Permeation, Sorption, and Polymer Swelling John](https://reader034.vdocuments.site/reader034/viewer/2022042712/5f8fd789afda5e3cb2382463/html5/thumbnails/18.jpg)
Proposed Fundamental Cause of Plasticization
pT
CO Chh
,
0400,22~2
⎥⎥⎥⎥
⎦
⎤
⎢⎢⎢⎢
⎣
⎡
∂
⎟⎠⎞
⎜⎝⎛∂
=υ
Partial Molar Volume
15
20
25
30
35
40
45
50
0 10 20 30 40 50 60 70
CO
2 Par
tial M
olar
Vol
ume
(cm
3 /mol
e)Pressure (atm)
Rubbery Asymptote
Plasticization Threshold
Swelling normalized by concentration
100 °C220 °C
Hypothesis: ↑ Polymer segmental mobility ↑ CO2 partial molar volume ↑ polymer “free volume”
supported by other data in literature (Bohning and Springer, Polymer, 1998)