1 movie of co 2 and h 2 permeation movie courtesy of josh chamot, nsf:
TRANSCRIPT
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Movie of CO2 and H2 Permeation
QuickTime™ and aSorenson Video 3 decompressorare needed to see this picture.
Movie courtesy of Josh Chamot, NSF:http://www.nsf.gov/news/news_summ.jsp?cntn_id=105797&org=NSF
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Membrane Hydrogen Purification: Classic
• H2/hydrocarbon separation
• H2/CO ratio adjustment
• NH3 purge gas recovery
Hydrotreater
TreatedOil
Hydrotreater
H2
Oil
(1) InertsPurge
(3) FuelGasMembrane
Oil/GasSeparator
(2) Recovered H2
Photo from Air Liquide
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• Steam reforming of hydrocarbons accounts for 95% of the hydrogen produced in the U.S. (DOE 2003):
• U.S. H2 production was 810 million kg/yr in 2003. (DOE)– Growth due to:
• Low grade crude in refineries• Power source for fuel cells
DOE = http://www.eere.energy.gov/hydrogenandfuelcells/
Fuel Cell Facility (PLUG)
PLUG = http://www.plugpower.com/technology/overview.cfm
• Membranes may be useful for purifying H2: - Low capital costs - Compact size - Ease of operation
Interest in HydrogenInterest in Hydrogen
CH 4 + 2H2O→ CO2 + 4H2
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Fuel Cell OperationFuel Cell OperationFrom Jim McGrath, Virginia TechFrom Jim McGrath, Virginia Tech
Source: H Power
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Just what the environment Just what the environment needs from a car. needs from a car. WaterWater..
Hydrogen powered Fuel Cell vehicles only emit water.
From Jim McGrath, Virginia Tech
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H2 Purity Requirements for Fuel Cells
A National Vision of America’s Transition to a Hydrogen Economy - 2030 and Beyond, U.S. DOE, 2/2002.
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Cost Estimates for H2 Production
http://www.eere.energy.gov/hydrogenandfuelcells/pdfs/vision_doc.pdf
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FutureGen
"Today I am pleased to announce that the United States will sponsor a $1 billion, 10-year demonstration project to create the world's first coal-based, zero-emissions electricity and hydrogen power plant..."
President George W. Bush
February 27, 2003
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Current applications:
• Air separation - mainly N2 enriched air
• Natural gas treatment - acid gas removal• H2 separation - H2 from hydrocarbons, ammonia purge, syngas
• Removal of vapors from mixtures with light gases (vapor separation)Advantages:• Low energy separation (no phase change)• Reliable (no moving parts)• Small footprintDrawbacks:• Incomplete separation (need higher selectivity)• Low chemical/thermal stability (need more resistant matls.)
Gas Separations Using Membranes
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• High flux (high permeability, thin)
• High selectivity
• Tolerance to all feed components
• Mechanical stability
• Ability to be packaged in high surface area modules
• Excellent manufacturing reproducibility, low cost
Ideal Membrane Characteristics
16D. Wang, et al., ACS Symp. Ser., v. 744, p. 107, 1999.
~5,000 m2/m3
Contaminated Natural Gas(High Pressure)
CO2- rich permeate(Low pressure)
Upgraded Natural gas(High Pressure)
Hollow Fiber Module
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Component Spe c ificat io n
CO2 <2%
H2O <120 ppm
H2S <4 ppm
C3+ hydroca rbons 950 -1050 Btu/ft3(S TP)
Dew Point -20C
Inerts (N2, CO2, He , e tc.) <4%
Amine Scrubber
Membrane Unit
U.S. Pipeline Specifications1:
Potential membrane applications:• Acid gas removal• N2 removal• Higher hydrocarbon removal• Dehydration1R.W. Baker, I.&E.C. Res., 41, 1393 (2002).
Natural Gas Purification
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JA
Membrane thickness
Upstream pressure
p feed
Downstream pressure
pperm
l
Component A
Component B
pfeed > pperm
(1) Sorption on upstream side(2) Diffusion down partial pressure gradient(3) Desorption on downstream side
• Permeability of A ≡ PA = DA SA , where DA ≡ Diffusion coefficient of A SA ≡ Solubility coefficient of A
• Selectivity ≡ α /A B =PA
PB=
DA
DB
⎛
⎝⎜
⎞
⎠⎟
SA
SB
⎛
⎝⎜
⎞
⎠⎟
Mobilityselectivity
Solubilityselectivity
• Flux of A≡ JA =PA (p ,feed A - p ,perm A)
l
J. Membr. Sci., 107, 1-21 (1995)
Gas Transport in Polymers: Solution-Diffusion Model
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10 -13
10 -12
10 -11
10 -10
10 -9
10 -8
10 -7
10 -6
50 100 150 200 250 300
Permeability [cm
3
(STP)
•
/(cm cm
2 •s•
)]cmHg
Vc [cm3 / ]mole
, 35°PDMS C
, 23°PSF C
H2
O2
N2
CO2
CH4
C2H6
C3H8
H2
He
O2
NH3
N2
CH4
CO2
SF6
CCl2F2 C
2Cl
2F4
PDMS:
nSi O
CH3
CH3
SO2 O C
CH3
CH3
O
n
PSF:
Characteristic Polymer Permeation PropertiesCharacteristic Polymer Permeation Properties
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10 -12
10 -11
10 -10
10 -9
10 -8
10 -7
10 -6
10 -5
10 -4
10 100 1000
Diffusion Coefficient [cm
2/s]
Vc [cm3 /mole]
PDMS
PSF
H2O
2
N2
CO2
CH4
CF4
C2H
6C
3H
8
C2F
6 C3F
8
He
O2
N2
CO2
CH4
C4H
10
10 -4
10 -3
10 -2
10 -1
10 0
0 100 200 300 400 500
Solubility [cm
3
(STP)/(cm
3•
)]cmHg
Tc [ ]K
PSF
PDMS
H2 N2 O2CH4 CO 2 C3H8 -n C4H10
C2H6
B.D. Freeman and I. Pinnau, "Polymeric Materials for Gas Separations," in Polymeric Membranes for Gas and Vapor Separations: Chemistry and Materials Science, Edited by B.D. Freeman and I. Pinnau, ACS Symp. Ser. 733, pp. 1-27 (1999).
Solubility and Diffusivity CharacteristicsSolubility and Diffusivity Characteristics
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• Traditional membrane materials• Glassy polymers• Designed to be strongly size-sieving
• Low permeability• High selectivity due to high diffusion selectivity
• Upon plasticization, selectivity decreases, sometimes strongly
• H2 selective in H2/CO2 separations
• Our approach• Rubbery polymers
• Designed to be strongly solubility-selective• High permeability• Selectivity derives primarily from high solubility selectivity
• Upon plasticization, separation properties can increase in some cases (CO2/H2)
Materials Design ApproachPA =SADA αA/B =
SA
SB
DA
DB
O
H3C C N
THF
ACN
Effect of Polar Groups in Liquid Solvents on Effect of Polar Groups in Liquid Solvents on COCO22 Solubility and CO Solubility and CO22/N/N22 Solubility Solubility Selectivity Selectivity
Lin and Freeman, J. Molecular Structure, 739(1-3), 57-74 (2005).
1
10
100
1
10
100
10 15 20 25 30 35
CO2
Solubility [cm
3
(STP)/(cm
3
atm)]
CO2
/N2
Solubility Selectivity
THF
AN
ACN
DMFC6 MeOHDMS
MAc
TCM
PC
Solvent Solubility Parameter [MPa 0.5 ]
THF ACN
25oC
R=CH3; poly(ethylene glycol) methyl ether acrylate (PEGMEA); n=8R=H; poly(ethylene glycol) acrylate (PEGA); n=7
Poly(ethylene oxide) diacrylate (PEGDA: Crosslinker)
UV
n
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][ OCH 2CH 2O
O
CCHCH 2 C
O
CH CH 2
C
C
OO
CC
CC
CC
PEOO
PEO
C
CO
PEO
OR
C
C
PEO
OR
O
O
C
O
C
PEO
O
OO
OC
CC
CC
C
CH2 CH C
O
O CH2 CH2 OR[ ]
Crosslinked Poly(ethylene oxide) [XLPEGDA]
Mixed Gas Separation
10-1
100
101
102
10-2 10-1 100 101 102 103 104
CO
2/H
2
α
CO2 [ ]Permeability Barrer
Upper Bound35oC
10oC
-20oC
Lin, Haiqing, E. van Wagner, B.D. Freeman, L.G. Toy, and R.P. Gupta, “Plasticization-Enhanced H2 Purification Using Polymeric Membranes,” Science, 311(5761), 639-642 (2006).
Mixed Gas CO2/CH4 Separation
PEGDA (crosslinker; 30wt %) CH2 CH C
O
O CH2 CH2 OCH3[ ]8
PEGMEA (monomer: 70 wt%)
]13[ OCH2CH2O
O
CCHCH2 C
O
CH CH2
0
10
20
30
40
50
0 5 10 15 20
CO
2/CH
4
α
CO2 [ ]Partial Pressure atm
35oC
/ -30PEGDA PEGMEA
mixed
6 -FDA mPD
Pure
100
101
102
100 101 102 103 104 105
CO2 Permeability [Barrer]
CO
2/CH
4
αCA
-20oC
10oC
35oC
upper bound
Lin, Haiqing, E. van Wagner, B.D. Freeman, and I. Roman, “High Performance Polymer Membranes for Natural Gas Sweetening,” Advanced Materials, 18, 39-44 (2006).