2004 DEER Conference - P2RIC

2004 DEER ConferenceAugust 29 – September 2, 2004

Coronado, California



Aftertreatment Requirements for the Future

• 80 – 90 % NOx reduction• Wide temperature range• Same low PM, HC levels• Limited impact on fuel consumption• Packaging• Competitive cost• Durability of up to

– 1 million miles (Truck)– 10,000 hrs (off-highway)



System Development Process• Understanding of catalyst behavior• Integration: Alignment of catalyst needs and engine

system capabilities• Control system/algorithm development• Catalyst size and cost optimization

– Various engine platforms and ratings– Various engine cycles– Real life application– Durability



System Development Process

i=1Exhaust Gas

Volume

Catalyst Surface

,...),],NO([]NO[ PTxfdtxd=

i=1Exhaust Gas

Volume

Catalyst Surface


i=1Exhaust Gas

Volume

Catalyst Surface


Bench Testing

ModelingResearch

Supplier Relationships

Design and Packaging

Catalyst Formulation Development

Engine / Aftertreatment

System Integration

Combustion development



Caterpillar/Xytel MRCSS Catalyst Test BenchMass flow controllers,

switching valves

lean/rich

...

H2OInlet gas mixture

Heat from ovens

TC for closed-loop

temperature control

Gas Cylinders:

NO, NO2, O2, N2, CO2, CO, C3H6,

NH3, H2

Flow rates

NOx adsorber sample

Analyzers

CO2

Dryer NOx

Outlet gas mixture

etc.



Bench Tests: Quantitative Data

NOx Slip vs Time

0

5

10

15

0 20 40 60

time (sec)

NO

x sl

ip (

ppm

)

NO

x Co

nver

sion

NOx Adsorber Catalyst behavior

Temperature (°C)

Catalyst “mapping”

Flow rate 1

Flow rate 2



Aftertreatment Performance Model• Reduce bench data to generalize Catalyst behavior

(“mapped” catalyst)• Can be linked to full engine system model• Couple with transient exhaust-gas emissions data

– Temperatures– SV– Emission levels

• Predict system behavior– Transient emissions– Effect of active control measures– Thermal behavior– Aging/degradation prediction



NOx Adsorber Technology Requirements

• 80 – 90 % NOx reduction• Limited impact on Fuel Consumption• Packaging• Competitive cost

• Main Issue: Durability• Sulfur deactivation• Thermal deactivation• Phosphorus deactivation



Case study: Modeling Phosphorus effect

Long term deterioration from phosphorus deactivation

• Phosphorus (or other ash components) in lube oil can degrade catalyst performance

• Model can be used to predict effects of long-hours Phosphorus accumulation

• Compare transient simulation results with and without Phosphorus deactivation

• Results from APBF study will be used as baseline for simulation



Baseline: APBF heavy duty NOx Adsorber• APBF-DEC program investigated effect of fuels on

aftertreatment durability (2000 hrs)• Modified heavy duty Cummins 15 l engine (2004

emission level)• “Single leg” NOx Adsorber system• NOx adsorber volume: 44 liters• Study performed by NREL and Ricardo Inc, Chicago

Technical Center

NAC1

DOCDOC

DPF

NACDPF

NAC

NOx Sensor

NOx Sensors



Baseline modeling• APBF was not involved in modeling activities by Caterpillar• Phosphorus deactivation was out of scope of APBF program

• Caterpillar used FTP results reported by NREL and Ricardo as input for model

• NOx adsorber model was estimated from reported results of catalyst used by APBF

50556065707580859095

100

0 200 400 600 800 1000

Time [s]

NOx

Trap

ping

[%]

450degC

400degC

350degC

300degC

250degC



Model validation: Hot FTP after 2000 hrs

NOx ConversionMeasured: 95 %Simulated: 94 %

NOx tailpipe: ~ 0.2 g/hphBaseline: Catalyst out measured by Ricardo

Hot FTP after desulfation simulation after 2000 hrs

0.0

200.0

400.0

600.0

800.0

1000.0

1200.0

0.00 5.00 10.00 15.00 20.00Time [minutes]

NO

x [p

pm]

0

10

20

30

40

50

60

70

80

90

100

Con

vers

ion

Effic

ienc

y [%

]

Engine out Catalyst out simulated Conversion simulated



Caterpillar FTP prediction after 10,000 hrs•Simulated Conversion @ 10,000 hrs: 84%

•Catalyst model was modified for Phosphorus effect

Hot FTP after desulfation simulation after 10,000 hrs

0100200300400500600700800900

100011001200

0.00 5.00 10.00 15.00 20.00Time [minutes]

NO

x [p

pm]

0

10

20

30

40

50

60

70

80

90

100

Con

vers

ion

Effic

ienc

y [%

]

Engine out Catalyst out 2000 hrs Catalyst out 10,000 hrsConversion 2000 hrs Conversion 10,000 hrs



Predicted deterioration due to Phosphorus deactivationHot FTP Cycle Results

NOx Adsorber Aging on 15 ppm Fuel

0.0

0.2

0.4

0.6

0.8

1.0

0 2000 4000 6000 8000 10000Age (hours)

NO

x (g

/bhp

-hr)

NOx Mean - Fresh and Pre-Desulfation Desulfation NOx Mean - Post-Desulfation

End of APBF testAfter desulfation

Caterpillar predicted after-desulfation performance

10,000 hrs

APBF measurements(no investigation into Phosphorus)



Conclusion• NOx Adsorber Technology is a promising candidate

for future NOx reduction, BUT…..

• Durability is still a significant challenge• Phosphorus effect should not be neglected, not

easily reversible• Phosphorus can have a significant effect on long

term catalyst performance• More focus needed to understand long-term

performance degradation• Ashless lubricants would be a major benefit to NOx

adsorbers and other aftertreatment devices

2004 DEER Conference - P2RIC

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