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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

3

• 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

4Air Liquide Slides courtesy of Dr. Greg Fleming, UT Ph.D. ‘87

5

6

Air Products Slide courtesy of Dr. Lloyd Robeson

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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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FutureGen Concept

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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

15

• 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

19

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

14

][ 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).

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THANK YOU!