Presentation Identifier (Title or Location), Month 00, 2008

Structured Oxide-Based Reforming Catalyst Development

11th Annual SECA Workshop, Pittsburgh, PAJuly 29, 2010

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Introduction• Reform HCs into H2 and CO-rich gas stream for solid

oxide fuel cell (SOFC) applications

Diesel

Fuel

ProcessorSyngas

SteamFC

Stack

Reforming TechnologiesPower

Fuel Cell Systems

Applications

Fuel

Syngas (H2, CO, CH4...)

Plasma

• Stationary• Military• Transportation

Coal

Fuel Sources

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Primary Goal

Identify, evaluate and/or develop viable hydrocarbon fuel processingtechnologies for high temperature solid oxide fuel cells being supported inthe NETL SECA program through fundamental understanding, research,and technology demonstration.

Fuel Technology End Use

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Two Project Areas

Oxide-Based Catalyst Systems:

Apply fundamental understanding of fuel reforming & deactivation mechanisms into intelligent design of alternative catalyst systems for long-term, stable hydrogen-rich synthesis gas production.

Advanced Reforming Concepts:

Identify and evaluate alternative non-catalytic and/or catalyst assisted processes to overcome deactivation of traditional catalytic fuel reforming of higher hydrocarbon fuel compounds.

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Structured Catalyst Development• Objective: Apply fundamental understanding of fuel reforming &

deactivation mechanisms into design of alternative catalyst systems for long-term, stable hydrogen-rich synthesis gas production.

• Technical objectives / challenges

• Reforming catalyst formula development

• Reforming studies with diesel surrogate fuel

• Oxygen-conducting support studies

• 1000-hr OSR demonstration test on pump diesel

• Development of commercially viable catalyst structure (monolith)

• Short-term OSR studies with diesel fuel on catalyst monolith

• 100-hr OSR demonstration test with biodiesel in integrated fuel cell test

• Graded bed approach

• RF-assisted catalytic reforming

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Reformer Integration

FuelReformer

FuelCell

Stack

Cathode

Anode

Q

Air

Fuel

Reforming Options: POx

Steam Reforming

Oxidative SR

Steam

Q

22mn H2mnnCOOnHHC

++→+Steam Reforming - Endothermic

Q

( ) 2222mn N2n3.76H

2mnCO3.76NO

2nHC

++→++POx Reforming - Exothermic

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• Desired Thermal Integration with Fuel Cell – Similar Temperature of Operation:

Reduces unnecessary heat exchange and can increase system efficiency – cost & complexity savings.

Challenges: Thermal processes require too high temperatures. Can be achieved by utilizing catalysts to lower reformation temperatures. Unfortunately, most hydrocarbon fuels contain sulfur and complex hydrocarbons that deactivate catalyst systems prematurely. Commercial catalysts developed mostly for natural gas reformation & naphtha.

• Possible Low or Waterless Operation: Reduces or eliminates the complexity and cost of managing water

within the system. Some applications cannot consider water addition to the process.

Challenges: The use of water (usually excess) is the principle combatant to carbon formation for commercial catalysts. Water however can also increase system efficiency by increasing hydrogen concentration via steam reforming & heat utilization: Cost vs efficiency trade-off.

Technical Objective / Challenges

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Evolution of NETL Reforming Catalyst System

(1&2)

(3)

(1-3)

(1) Support sintering

(2) Sulfur poisoning

(3) Coke formation

Metal Particles Substituted into a Thermally Stable Oxide

Metal Particles Substituted into a Stable Oxygen-

conducting Oxide Metal Particles/

Metal Particles/

Oxygen-conducting

Metal Particles Substituted into a Stable

Oxide/OCS

Metal Particles Substituted into a Stable Oxide/

OC-film/High SA Support

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Oxide-based Catalyst Systems (Pyrochlores)

Doping the lattice of certain oxide-based compounds with catalytic metals results in…A structured catalytic surface with nano-sized metallic crystallites that serves as a template to control metallic crystallite size and dispersion.

A-site cationB-site cation

Oxygen anion

Pyrochlores (A2B2O7) are viable reforming catalysts because they exhibit: • High chemical and thermal stability [1]• Mechanical strength to accommodate

substitutions [2]• Active metal can be substituted into B-site to

improve catalytic activity • Substitution with lower valence elements in A-site

and B-site can create oxygen vacancies, which may increase lattice oxygen-ion mobility to reduce carbon formation.

[1] D. Sedmidubsky, et al., The Journal of Chemical Thermodynamics 37 (2005) 1098.[2] H. Zhou, et al., Journal of Alloys and Compounds 438 (2007) 217

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Micro-Reactor Setup

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Experimental conditions T=900 C, P= 0.25 MPa, GHSV= 50,000 sccm/g-hr

0

10

20

30

40

50

60

70

80

90

100

0 50 100 150 200 250 300 350

Time on stream (min)

Yiel

d (%

)

LSRZ

Rh/γ-Al2O3

5 wt% 1-MN & 1000 ppmw S added

5 wt% 1-MN & 1000 ppmw S removed

Pyrochlore for POx of Diesel Surrogate

A conductive oxide-based catalyst was doped with 1% Rh along with a SOA Rh catalyst on alumina. After exposure to a severely carbon producing fuel compound, the oxide-based catalyst performance remained stable, while the non-conducting supported catalyst deactivated significantly.

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Oxide Catalyst on Oxygen-Conducting Supports

Metal OxideCatalyst

Oxygen Conducting Catalyst Support

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1000-hr Demonstration of Pyrochlore Catalyst for Oxidative Steam Reforming of Pump Diesel

0

100

200

300

400

500

600

700

800

900

0

5

10

15

20

25

30

0 200 400 600 800 1000 1200

Ole

fins

Pro

duce

d (p

pm)

Com

posi

tion

(%)

Time on stream (hrs)

HydrogenCarbonMonoxideCarbonDioxideMethaneOlefins

H2

CO

CO2Olefins= ethylene + propylene + C4-ene + benzene

Water pump off Water

pump on

Fully reformed local pump diesel Equilibrium syngas yields achievedSurvived multiple system upsets O/C=1, H2O/C=0.5, T=900 C, P= 0.25 MPa, SV= 25,000 sccm/g-hr

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• Fabrication of Catalyst into a Commercially Viable Structure

• Powder Catalyst Validation:• Activity tests; TPO (carbon formation)• Bulk characterization – ICP, XRD

• Surface characterization – XPS, TPR, H2-chemisorption• Preliminary Tests on Coated Monolith

NETL’s Pyrochlore Catalyst in Powder

Form

Monolith Coated by NexTech

Microlith® Technology by

PCI

Diesel Fuel Reforming using Pyrochlore CatalystCollaboration with Industrial Partners

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Monolith Reactor Coated with Pyrochlore Catalyst

• NETL-developed Pyrochlorecatalyst deposited onto alumina monolith with oxygen-conducting interlayer

• Coated using proprietary method by Nextech Materials, Inc.

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Coated Monoliths from NexTech

Base Support: 400 cpi alumina-based

Coated Monolith: Incorporates NETL pyrochlore catalyst system

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Successful Operation of a Solid Oxide Fuel Cell Fueled with Syngas from Biodiesel Reforming

• Biodiesel was reformed for 100 hrs on a pyrochlore catalyst supported on a monolith

Biodiesel Reformer 0

5

10

15

20

25

30

35

40

45

50

16-Nov 17-Nov 18-Nov 19-Nov 20-Nov 21-Nov

Perc

ent C

ompo

sitio

n

Syngas Composition versus Time

Hydrogen

Carbon Monoxide

Carbon Dioxide

Methane

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Pyrochlore for Natural Gas Steam ReformingS/C = 0.9; TRXR = 700 C; GHSV = 25,000 scc/gcat•hr

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Graded Catalyst Bed Approach

Combustion

SR + WGS

Steam Reforming

~1100oC

CO2Reforming

+

High AromaticConcentration

~700oC

900oC

Low TempSulfur Poison

Rh-Pyrochlore

Ni, Pt, Ru-Pyrochlore/

Ni-HxAl

CombustionCatalyst

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0

5

10

15

20

25

0 60 120 180 240 300

Hyd

roge

n Co

ncen

trat

ion

(%)

Time (min)

0.49g C

0.71g C

1.13g C

1.88g C

1.41g C

1.31g C

Rh-Pyrochlore(LCRh1ZY)

Ni-Hexaaluminate(BNHA)

Preliminary Results: BNHA/LCRh1ZY

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Energy bands of atoms or molecules absorb the RF energy

Localized heating of the material at the rxn site with higher dielectric loss index and

excitation of valence electrons

Lowers the activation energy required for desired chemical

reactions

Functions as an enhanced catalyst

Alternative Reforming ConceptsRadio-Frequency Enhanced Reaction Concept

RF Antenna

Fuel & Air (in)

H2 & CO (out)

T=900C

Furnace

Catalyst

bed

22

50

55

60

65

70

75

80

85

0 1 2 3 4 5

H2 Y

ield

(%)

Time (hrs)

Baseline20W40W60W80W100W

50

55

60

65

70

75

80

85

0 1 2 3 4 5C

O Y

ield

(%)

Time (hrs)

Baseline20W40W60W80W100W

Alternative Reforming ConceptsRadio-Frequency Enhanced Reaction Concept

• Effect of RF power on Syngas yields at fixed frequency (13.6 MHz)• Preliminary results suggest that applied RF field has a positive influence on reforming• Also see a slight reduction in carbon (coke) formation on the catalyst bed when RF field

is applied• Further testing in underway to repeat these findings and understand the underlying

mechanism of enhanced catalyst activity

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Summary/Conclusions

• SOFC-based APUs for commercial diesel trucks is an excellent market entry technology– Reforming catalyst with long-term stability and performance is

critical for successful demonstration of transportation application

• Pyrochlore catalyst on oxygen-conducting support successfully reformed pump diesel for 1000-hr

• Optimized pyrochlore catalyst applied to commercially representative structured supports– Preliminary performance of catalyst monolith demonstrated

on pump diesel and biodiesel fuels under oxidative steam reforming

• Preliminary RF experiments have shown some evidence of reduced carbon formation and enhanced catalyst activity

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NETL Fuel Processing Team

• David Berry• Dushyant Shekhawat• Nick Siefert• Dan Haynes• Mark Smith• Mike Gallagher• Don Floyd• Mike Bergen• Prof. Jerry Spivey (LSU)

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Acknowledgements

• SECA• NexTech Materials