Development of Novel CO2-SelectiveMembrane for H2 Purification

W.S. Winston Ho

The Ohio State University, Columbus, OH

DOE Program Manager: Nancy L. Garland

ANL Technical Advisor: Thomas G. Benjamin

2004 Program Review, Philadelphia, May 24 - 27, 2004

This presentation does not contain any proprietary or confidential information.

Objectives

• Produce Enhanced H2 Product with <10ppm CO at High Pressure Used forReforming

• Overcome Fuel-Flexible Fuel ProcessorsBarrier L: H2 Purification/CO Clean-up

• Achieve Target: <10 ppm CO in ProductStream

Budget

• Total Funding for the Project

- $880,000 (10/01/01 – 09/30/04)

- DOE Share = $704,000

- Contractor Share = $176,000

• Funding for FY04 = $346,250

- DOE Share = $277,000

- Contractor Share = $69,250

Technical Barrier and Target

• DOE Technical Barrier for Fuel-FlexibleFuel Processors

- L: H2 Purification/CO Clean-up

• DOE Technical Target for Fuel-FlexibleFuel Processors for 2010

- < 10 ppm CO in Product Stream

Use CO2-Selective Membrane to:

• Remove CO2 for H2 Enhancement

• Drive Water-Gas-Shift (WGS) Reaction toProduct Side

CO + H2O H2 + CO2

• Decrease CO to <10 ppm via CO2 Removal

Approach

Fuel Processing with CO2-SelectiveMembranes for Fuel Cells

• Low Temperature CO2-Selective Membrane

• High Temperature CO2-Selective Membrane

Reformer

WaterGas

Shifter

Membrane Process

FuelCell

Hydrocarbon

H2

CO2

COH2O

H2

CO2

CO (Low)H2O

H2

CO2 (Trace)CO (Trace)

ReformerWGS

MembraneReactor

FuelCell

H2

CO2 (Trace)CO (Trace) Hydrocarbon

H2

CO2

COH2O

CO + H2O H2 + CO2

CO2-Selective Membranes by Incorporating Aminesin Polymer Networks … Facilitated Transport

Example: Polyvinylalcohol-Containing Amine Membrane

C

H

H

C

H

OH

C

H

H

C

H

OH

C

H

H

C

OH

H

C

H

H

C

OH

H

R3N

R3N

Membrane

R3N

CO2

R3N CO2CO2

+

H2

Project Safety

• CO Monitor / Alarm Installed Next to Membrane Unitsfor Personnel Safety

- Alarm Never Sounded So Far for >2.5 Years of Membrane Operations (MOs), Indicating Safe MOs

• N2 Purging Used in Ovens to Prevent CO / H2

Accumulation from Any System Leakage

- Ovens Provide Precise Temperatures for

Membrane Units for Accurate Exp. Measurements

- Locking Device Installed to Prevent N2 Purging

from Accidental Shutdown

• Membrane Units Housed in a Hood

- Locking Device Installed to Prevent Hood from

Accidental Shutdown

• Safety Vulnerability Techniques Used (HAZOP, FMEA)

Project Timeline 2001 2002 2003 2004 Task 4Q 1Q 2Q 3Q 4Q 1Q 2Q 3Q 4Q 1Q 2Q 3QPhase 1 1. Modeling Study to Show <10 ppm CO Feasible ___________

2. Synthesis of Novel Membranes ___________

Phase 2 3. Characterization of Membranes ____________ 4. Set-up of Lab Reactor ______ 5. Membrane Fabrication ____________ 6. Proof-of-Concept Demo ______

Phase 3 7. Set-up of Membr. Reactor _____ 8. Fabrication of Membrane Module/Device ___________ 9. Membrane Reactor Demo ____

Technical Accomplishments

• WGS Membrane Reactor Experiments Showed

< 10 ppm CO – Project Milestone Achieved

- Small Cell: Circular (Laboratory Membrane Cell)

- Big Cell: Rectangular with Well-defined Flow (7.5X Small Cell)

+ Data in Line with Model

• CO2 Removed Effectively to ~30 ppm

- In Line with CO2 Model Developed

• Membranes with High CO2/H2 & CO2/COSelectivities & High CO2 Flux Synthesized

• <10 ppb H2S Achieved Experimentally (Outside Project Scope)

- H2S Model Developed Shows This H2S

Achievable in Entrance Section

0

5

10

15

20

25

30

10 20 30 40 50 60 70 80

W t C t ti i F d (%)

Ex

it D

ry C

O C

on

c.

(pp

m)

40 cc/min

Feed

60 cc/min

Feed

6 cc/min

Feed

20 cc/min Feed

30 cc/min Feed

WGS Membrane Reactor Experiments

Showed < 10 ppm CO: Small Cell

Feed: 1% CO, 17% CO 2, 45% H 2, 37% N 2 (on dry basis)

150oC, 2.1 atm

CO2-Selective Membrane Reactor:Experiments and Modeling

H2 Feed CO2High H2 Product

Air, N2 or SteamAir with CO2

z = 0 7.8 in. (19.8 cm)

Big Cell

• Well-defined Gas Flow and Velocity• Suitable for Modeling and Scale-up

0

2

4

6

8

10

12

14

0 10 20 30 40 50 60 70

F d Fl R t ( / i )

Exit

Dry

CO

Co

nc. (p

pm

)

Model

Feed: 1% CO, 17% CO 2, 45% H2, 37% N2 (on dry basis)

150oC, 2 atm

WGS Membr. Reactor Experiments Showed

< 10 ppm CO in Line with Model: Big Cell

0

2

4

6

8

10

12

14

0 1000 2000 3000 4000 5000 6000 7000

C l l t d S V l it (GHSV h-1)

Exit

Dry

CO

Co

nc. (p

pm

)

150oC, 2 atm

Model

Calculated Space Velocity Based on

Experimental Data: Big Cell

1

10

100

1000

10000

0 10 20 30 40 50 60 70

Feed Flow Rates (cc/min)

Ex

it D

ry C

O2 C

on

c.

(pp

m)

CO2 Removed Effectively --

CO2 Concentration in Retentate

Feed: 1% CO, 19% CO 2, 43% H2, 37% N2 (on dry basis)

120oC, 1.6 atm, Big Cell

Sweep/Feed Molar Ratio = 1

Sweep: N2 or Steam

Model

Methanation Readily ConvertsCarbon Oxides to Methane

• Methanation (at ~160 – 180oC)

CO + 3 H2 CH4 + H2O

CO2 + 4 H2 CH4 + 2 H2O

• Important to Remove CO2 as Much asPossible before Methanation

• Exit CO Concentration < 5 ppm

H2S Removal Rate Expected to beFaster than CO2 Rate(Outside the Project Scope)

• CO2 Reaction via Mainly Carbamate Formation

2 R-NH2 + CO2 R-NH-COO- + R-NH3+

• H2S Reaction via Small Proton Transfer

… Very High Rate

H H + N NH+ + HS-

S

H2S

0

5000

10000

15000

20000

25000

30000

100 110 120 130 140 150

T t (oC)

Pe

rme

ab

ilit

y (

Ba

rre

rs)

CO2

H2S Has Higher Permeability than CO 2

2 atm

Feed: 50 ppm H2S, 1% CO, 17% CO2,

45% H2, 37% N2 (on dry basis)

(Outside the Project Scope)

1 Barrer = 10-10 cm3(STP)-cm/cm2-s-cmHg

H2S/H2 Selectivity Higher than

CO2/H2 Selectivity

0

200

400

600

800

1000

100 110 120 130 140 150

Temperat re (oC)

Se

lec

tiv

ity

vs

. H

2

2 atm

H2S

CO2

(Outside the Project Scope)

1.0E-24

1.0E-21

1.0E-18

1.0E-15

1.0E-12

1.0E-09

1.0E-06

1.0E-03

1.0E+00

1.0E+03

0 10 20 30 40 50 60 70

M d l L th ( )

Ex

it D

ry H

2S

Co

nc

. (p

pm

) 50 ppm Feed

2 ppm

Feed

5 ppm Feed

10 ppb

Modeling Shows <10 ppb H 2S

Achievable in Entrance Section (Outside the Project Scope)

0.01

0.1

1

10

100

5 10 15 20 25 30 35

F d Fl R t ( / i )

Exit

Dry

H2S

Co

nc. (p

pm

)

Feed with 1% CO, 17% CO2, 45% H2, 37% N2 (on dry basis)

120oC, 2 atm

Small Cell

H2S Removed Effectively: 50 ppm H2S Feed

(Outside Project Scope)

0

2

4

6

8

10

12

14

5 10 15 20 25 30 35

Ex

it D

ry H

2S

Co

nc

. (p

pb

)H2S Removed Effectively: 100 ppb H2S Feed

120oC, 2 atm

Small Cell

(Outside the Project Scope)

0.01

0.1

1

10

100

5000 10000 15000 20000 25000 30000

C l l t d S V l it (GHSV h-1

)

Exit

Dry

H2S

Co

nc. (p

pm

) 120 oC, 2 atm

Small Cell

Calculated Space Velocity Based on Exp. Data 50 ppm H2S Feed (Outdise the Project Scope)

Significant Interactions/Collaborations

• Work with Unitel Technologies / H2fuel onMembrane Scale-up

- Discussions with Auto Companies

• Collaboration with H2 Supplier for FuelCell Applications

• Presentations / Publications on

CO2-Selective Membranes

- 2 at AIChE 2003 Annual Meeting

- 6 Seminars at Universities / Companies

Responses to Reviewers’ Comments

• Recommend to Identify High-Temp Membrane

- Continued to Synthesize / Characterize

Membranes with Improved Thermal Stability

• Investigate Membrane Reactor Scale-up

- Built a Big Cell (7.5X Small Cell) with Well-

defined Flow Suitable for Modeling/Scale-up

- Showed Data in Line with Model Developed

• Generate a Detailed Model (Experimental)

- Developed WGS / CO2 Removal Models

- Showed Good Agreements between the

Models and Experiments

Future Plans

• Continue to Synthesize / CharacterizeMembranes with Improved Properties

• Investigate Membrane Stability

• Complete Membrane ReactorDemonstration

• Demonstrate <10 ppm CO via CO2

Removal and Methanation for Fuel Cells

• Look into More Active WGS Catalysts