Membrane Sep h

8/13/2019 Membrane Sep h

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Movie of CO 2 and H 2 Permeation

QuickTime™ and aSorenson Video 3 decompressor are needed to s ee 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

• NH 3 purge gas recovery

H y d r o t r e a t e r

TreatedOil

H y d r o t r e a t e r

H2

Oil

(1) InertsPurge

(3) FuelGasMembrane

Oil/GasSeparator

(2) Recovered H 2

Photo from Air Liquide



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• Steam reforming of hydrocarbons

accounts for 95% of the hydrogenproduced in the U.S. (DOE 2003):

• U.S. H 2 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 H 2: - Low capital costs- Compact size- Ease of operation

Interest in Hydrogen

CH 4 2 H

2O CO

2 4 H 2



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Fuel Cell OperationFrom Jim McGrath, Virginia Tech

Source: H Power



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Just what the environmentneeds from a car. Water .

Hydrogen powered Fuel

Cell vehiclesonly emitwater.

From Jim McGrath, Virginia Tech



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Cost Estimates for H 2 Production

http://www.eere.energy.gov/hydrogenandfuelcells/pdfs/vision_doc.pdf



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FutureGen

"Today I am pleased to announce that the UnitedStates will sponsor a $1 billion, 10-yeardemonstration project to create the world's first

coal-based, zero-emissions electricity andhydrogen power plant..."President George W. Bush

February 27, 2003



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FutureGen Concept



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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 m 2 /m 3

Contaminated Natural Gas(High Pressure) CO 2- rich permeate(Low pressure)

Upgraded Natural gas(High Pressure)

Hollow Fiber Module



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Component Specification

CO 2 <2%

H2O <120 ppm

H2S <4 ppm

C 3+ hydrocarbons 950-1050Btu/ft 3(STP)

Dew Point -20C

Inerts (N 2, CO 2, He, etc.) <4%

Amine Scrubber

Membrane Unit

U.S. Pipeline Specifications 1:

Potential membrane applications:• Acid gas removal• N2 removal• Higher hydrocarbon removal• Dehydration1R.W. Baker, I.&E.C. Res., 41, 1393 (2002).

Natural Gas Purification



18J. 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 P e r m e a

b i l i t y [ c m

3 ( S T P )

c m

/ ( c

m 2

s c m

H g

) ]

Vc [cm 3 /mole]

PDMS, 35°C

PSF, 23°C

H2

O 2N2

CO 2

CH 4

C 2H6C 3H8

H2

He

O 2

NH 3

N2

CH4

CO 2

SF 6

CCl2F

2 C 2Cl 2F4

PDMS: n

Si O

CH 3

CH3

SO2

O C

CH3

CH3

O

n

PSF:

Characteristic 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

D i f f u s

i o n

C o e

f f i c

i e n

t [ c m

2 / s ]

Vc [cm 3 /mole]

PDMS

PSF

H2O 2

N2

CO 2

CH 4

CF 4

C 2H6C 3H8

C 2F 6 C 3F8

He

O 2

N2

CO 2

CH 4

C 4H10

10 -4

10 -3

10 -2

10 -1

100

0 100 200 300 400 500

S o l u b i l i t y [ c m

3 ( S T P ) / ( c m

3

c m

H g

) ]

T c [K]

PSF

PDMS

H2 N2 O 2CH 4 CO 2 C3 H8n-C 4 H10

C2

H6

B.D. Freeman and I. Pinnau, "Polymeric Materials for Gas Separations," in Polymeric Membranes forGas 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 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 H 2 /CO 2 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 insome cases (CO 2 /H 2)

Materials Design Approach P

A S

A D

A A / B

S A

S B

D A

D B



O

H3C C N

THF

ACN

Effect of Polar Groups in Liquid Solvents onCO 2 Solubility and CO 2 /N 2 Solubility 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 C O

2 S o

l u b i l i t y [ c m

3 ( S

T P ) / ( c m

3 a

t m ) ]

C O

2 / N

2 S o

l u b i l i t y S e

l e c

t i v i t yTHF

AN

ACN

DMFC6 MeOHDMS

MAc

TCM

PC

Solvent Solubility Parameter [MPa 0.5 ]

THF ACN

25 o C



R =CH 3; poly(ethylene glycol) methylether acrylate (PEGMEA); n=8

R =H; poly(ethylene glycol) acrylate(PEGA); n=7

Poly(ethylene oxide) diacrylate (PEGDA: Crosslinker)

UV

n

14] [ O CH 2 CH 2 O

O

C CH CH 2 C

O

CH CH 2

C

C

O O

C C

C C

C C

PEO O

PEO

C

C O

PEO

OR

C

C

PEO

OR

O

O

C

O

C PEO

O

O O

O

C C C C C C

CH 2 CH C O

O CH 2 CH 2 OR [ ]

Crosslinked Poly(ethylene oxide) [XLPEGDA]



Mixed Gas Separation

10 -1

10 0

10 1

102

10 -2 10 -1 10 0 10 1 10 2 10 3 10 4

C O

2 / H

2

CO2 Permeability [Barrer]

Upper Bound35 oC

10 oC

-20 oC

Lin, Haiqing, E. van Wagner, B.D. Freeman, L.G. Toy, and R.P. Gupta, “Plasticization -Enhanced H 2 Purification Using Polymeric Membranes,” Science, 311(5761) , 639-642 (2006).



Mixed Gas CO 2 /CH 4 Separation

PEGDA (crosslinker; 30wt %)

CH 2 CH C

O

O CH 2 CH 2 OCH 3[ ]8

PEGMEA (monomer: 70 wt%)

]13[ O CH 2 CH 2 O

O

C CH CH 2 C

O

CH CH 2

0

10

20

30

40

50

0 5 10 15 20

C O

2 / C H

4

CO 2 Partial Pressure [atm]

35 oC

PEGDA/PEGMEA-30

mixed

6FDA- m PD

Pure

10 0

101

10 2

10 0 10 1 10 2 10 3 10 4 10 5

CO 2 Permeability [Barrer]

C O

2 / C H

4

CA

-20 oC

10 oC

35 oC

upper bound

Lin, Haiqing, E. van Wagner, B.D. Freeman, and I. Roman, “High Performance PolymerMembranes for Natural Gas Sweetening,” Advanced Materials, 18 , 39-44 (2006).



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Membrane Sep h

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