PROPANE STEAM REFORMING FOR FUEL CELLS

By Tamika Brown

H2

O2

H2

What is a Fuel Cell, and how does it work?

H2

H2

H2

H2

H2O2

O2

O2

O2

O2

H+

H+

H2O

H2OH2O

e- e-

AnodeElectrolyte

Cathode

O2

•A fuel cell is an electrochemical devicethat combines hydrogen fuel and oxygenfrom air to produce electricity and water.

•In a Polymer Electrolyte Fuel Cell, Hydrogen ions form at the anode, and diffuse through the electrolyte and reactwith oxygen at the cathode.

•Anode: H2 → 2H + (aq) +2e-

•Cathode: ½ O2 + 2H + (aq) + 2e- → H2O (l)

Uses of Fuel Cells• Transportation:

– Phosphoric Acid Fuel Cell• Anode: H2(g) → 2H + (aq) + 2e-

• Cathode: ½ O2 (g) + 2H+ (aq) + 2e- → H2O(l)

• Portable:– Proton Exchange Membrane Fuel Cell

• Anode: H2(g) → 2H + (aq) + 2e-

• Cathode: Cathode: ½ O2 (g) + 2H+ (aq) + 2e- → H2O(l)

• Stationary:– Solid Oxide Fuel Cells

• Anode: H2(g) + O2→ H2O(g) + 2e-

• Cathode: ½ O2 (g) + 2e- → O2-

Fuel Cell uses

• Fuel Cell transit buses in Chicago (Ballard Corp)

– Anode: H2(g) → 2H + (aq) + 2e-

– Cathode: ½ O2 (g) + 2H+ (aq) + 2e- → H2O(l)

• Energy Research Corp.– Anode: H2(g) + 2CO3 → H2O(g) + CO2(g) + 2e-

– Cathode: ½ O2 (g) + CO2 + 2e- → 2CO3

Hydrogen

• Hydrogen is the most abundant element in the universe

• No known sources of gaseous hydrogen• Hydrogen generated from another energy

source such as petroleum or from water through electrolysis– energy (electricity) + 2 H2O ->  O2  + 2

H2

SO HOW DO WE GENERATE AN ADEQUATE SUPPLY OF HYDROGEN FOR FUEL CELLS . . . . .

Fuel Processor/Reformer • Reformers convert hydrocarbon fuels into hydrogen• Steam and/or oxygen along with a catalyst are needed• Carbon dioxide is a byproduct

FuelProcessor

Fuel CellStack

Spent-GasBurner

Thermal & Water Management

Air

Air

Fuel

H2

Exhaust

Electric Power

Conditioner

3 Types of Reactions

*Steam Reforming:– Hydrocarbon+ Steam + catalyst → H2 + CO2

• Partial Oxidation Reforming:– Hydrocarbon + Oxygen + catalyst → H2 + CO2

• Autothermal Reforming:– Hydrocarbon + Oxygen + Steam + catalyst → H2 + CO2

Why choose Steam Reforming?

• Tailor to application– Ex. This particular investigation focuses on

stationary uses such as power plants and industrial plants

• Partial Oxidation (POx) can be tailored to meet certain vehicle regulatory standards

• Autothermal Reforming (ATR) is a thermal balance between (POx) and Steam Reforming

What is Hydrocarbon Source?

• Liquefied Petroleum Gas (LPG), • Consists mainly of propane, propylene,

butane and butylenes in various mixtures. • In the U.S. the mixture is mainly propane.

Why choose LPG?

• LPG can be used in the home, commercial businesses, industry, and transportation

• The residential and commercial markets where LPG is used make up about 50% of the world total LP gas retail sales

Fuel Processor/Reformer

1.Inlets to Reactora) Water → Steamb) Fuel (liquid) → Vaporc) Fuel (gas)d) Air (POx or ATR)e) Catalyst

2. Reactora) Sampling ports

3. Analytical Traina) CO/CO2 detectorb) Mass flow indicator

CO / CO2Monitor

Chiller0°C

Drain

N.O.

to vent

N.C.

to vent

3VSol-163

RV-162

to vent

PV-164

MV-167

Dotted lines show- - - Automatic Shutdown

components .

Drierite trap

PV-161

to vent

condensate trap

MFI-170

IF-169

PV-136

Fuel

Water

Vaporizer

N2

Furn

ace

CV-309

200°C

750°C

MFC-316

HPLC-301

HPLC-302

System Diagram

to vent

IF-148

IF-312

IF-311

SV-303

PV-304

RV-305

PV-306

CV-332

PV-333RV-331

3V-134

to vent

Condenser

Fuel

MFC-320

MFC-319

CV-323

SV-324

PV-322

Flame Arrestor

PV-171

sampling port

Dial Pressure Gauge

IF-147

PV-310

to vent

Air

MFC-318

N.C.

CappedN.O.

CV-307

3VSol-308

PV-321

MFC-317 PV-320

Condensate trap

Dark lines are heat wrapped at 150°C

MPV-330

IF-340 to 345

PV-346

From microreactor #2

Hydrocarbon + H2O(g) + catalyst → H2 + O2

What are the Goals of Experimentation?

• Explore how operating conditions affect the reaction kinetics– Variables: temperature, flow rates, catalyst

• Data from reactor model → kinetics → full scale reactor design for commercial use

Challenges of Reforming Process

• Flow Rates:– High efficiency is desired at faster flow rates

» Waste less fuel and energy, less catalyst

• Cost:– Parts can be expensive, as well as precious metal coated

catalysts.• Catalyst:

– Catalyst needs to withstand impurities such as sulfur, but also produce the most amount of hydrogen possible

• Temperature:– High efficiency needs to be achieved at lower temperatures

» Less of a hazard, cost of parts is cheaper, and less energy is needed to maintain system

Challenges Continued• Response times:

– Don’t want to have to wait periods of time for hydrogen to be produced in order for fuel cell to start working.

• Durability:– Catalyst and Reformer need to be durable

• Coking:– Carbon deposits in the reformer

» This causes clogging in the system

• Interference of components in fuel mixture– Alkenes interfere with alkane reforming

» This is a problem for LPG, because it is not a homogenous mixture

Conclusion

• If we switch to a hydrogen economy– More efficient than combustion

• Less air pollution (NOx, SOx, COx)

– Easily transportable– Save money (less imports)

• Fuel Reforming for Fuel Cells is an intermediary technology for the production of hydrogen until a renewable source of energy can be discovered.

Acknowledgments

I would like to thank John Kopasz for giving me the opportunity to participate in this and other research projects. I would like to thank Dan Applegate for his knowledge and helpfulness. I express sincere gratitude to Laura Miller for her patience, time, and wisdom. Last but not least, I would like to thank the U.S. Department of Energy for giving students a change to grow scientifically as well as professionally.

References• “What is a Fuel Cell.” Fuel Cells 2000. 2 March 2004.• http://www.fuelcells.org/whatis.htm• Carter, David, “Fuel Cell Power: What’s taking so long?”• IPMI 25th International Precious Metals Conference, June 9-12, 2001.• “Electrolysis: Obtaining hydrogen from water: The Basis for a Solar-Hydrogen

Economy.” 4 April 2005. http://www.nmsea.org • “Chicago’s Fuel Cell Buses Mobilized.” Hydrogen Newsletter Winter 1998: Hydrogen

Buses. 4 April 2005. http://www.hydrogenus.com/advocate/ad31cta.htm• “Pocket-size PEMs.” Pocket-size PEMs. 4 April 2005.

http://www.memagazine.org/backissues/february2000/features/pems/pems.html• Miller, Laura, “Safety Review for Long Term Test Reactor CMT50-0006-EP-Rev 08

NEPA Document ER-281.” February 17, 2005 pp. 1-15.• Laura, Miller, “Science Careers in Search of Women Conference.” March 10, 2005.• “What is Propane?” Alternative Fuels Data Center: What is Propane?” 23 March

2005. http://www.eere.energy.gov/afdc/altfuel/whatisprop.html.• “What is LP Gas?” World LP Gas Association. 29 March 2005.

http://www.worldpgas.com/mainpages/aboutpgas/whatislpgas.php.