New Pt-Pd Coating for Diesel Oxidation Catalyst

Dr. Toni KinnunenDr. Andreina MorenoDr. Kauko KallinenAuli SavimäkiSergio Del ReOsmo Jahkola

Introduction

• Engine and laboratory tests were perfomed to compare Pt-only and Pt-Pd

oxidation catalysts for diesel applications

• Pt-only catalyst: Current Ecocat DOC washcoat

• Pt-Pd catalyst: Next generation Ecocat DOC washcoat

• Catalysts: 90 g/ft3 Pt-only catalyst vs 70 g/ft3 Pt-Pd (4:1) catalyst. Light duty

• Heavy duty studies: 40 g/cft Pt-only vs 30 g/cft Pt-Pd (4:1).

• Same Ecocat® substrate was used for both catalysts in engine tests

Light-Duty studies

Engine TestsLaboratory Tests

Furnace

Catalystin reactor

PreheaterN2

COCO2

NO

Air

C3H6

Heated lines180 °C

Fridge

C3H8Other

FTIR-analyzer

NO/NOx-analyzerCO/CO2-analyzerO2-analyzer

Computer

THC/CH4-analyzer

Heatedsamplingunit

Mas

sfl

ow

con

tro

llers

Syringepump forliquids

Waterpump

Controlcenter

Aftertreatment system: CC+UF

Engine: 1,9 l, 4-cylinder, 74 kWCalibration: Euro IV

EcoCat® Substrate

Fresh engine test results (CC-only LD Euro 4)

0,17

0,493

0,212

0,556

0

0,1

0,2

0,3

0,4

0,5

0,6

THC CO

Em

issi

ons

g/K

m

Current Pt-only, 90 g/cft New Pt-Pd, 4:1, 70 g/cft

Light-Duty studies

Aged (HT800 / 20h) engine test results (CC-only LD Euro 4)

0,237

0,936

0,247

0,852

00,10,20,30,40,50,60,70,80,9

1

THC CO

Em

issi

ons

g/K

m

Current Pt-only, 90 g/cft New Pt-Pd, 4:1, 70 g/cft

Light-Duty studies

Deterioration factors:

1,39

1,9

1,17

1,53

0

0,2

0,4

0,6

0,8

1

1,2

1,4

1,6

1,8

2

DF THC DF CODF(

Em

issi

ons

aged

/Em

issi

ons

fres

h)

Current Pt-only, 90g/cft New Pt-Pd, 4:1, 70 g/cft

Light-Duty studies

DF = Emissions agedEmissions fresh

Laboratory EDC simulation –Gas mixture composition

BalanceN2

1000 ppmC3H6

1000 ppmCO

4.5 %CO2

4.5 %H2O

200 ppmNO

12 %O2

ConcentrationComponent

= 2.573

Purpose is to compare the

behavior of Pt vs. Pt-Pd

catalysts with a mixture

containing higher amounts

of CO and THC

Engine calibrations possiblyEngine calibrations possiblyused in future diesel vehiclesused in future diesel vehiclesto reduce emissionsto reduce emissionsNONOXX

Light-Duty studies

Laboratory EDC simulation results –THC fresh

0

20

40

60

80

100

120

0 200 400 600 800 1000 1200

Co

nve

rsio

n(%

)/

Sp

eed

(km

/h)

0

50

100

150

200

250

300

350

Tem

per

atu

re(°

C)

Speed Current 90 g/cft Pt New Pt-Pd 4:1 70 g/cft Temp.

Light-Duty studies

Laboratory EDC simulation results –THC aged (HT800/20h)

0

20

40

60

80

100

120

0 200 400 600 800 1000 1200

Co

nve

rsio

n(%

)/

Sp

eed

(km

/h)

0

50

100

150

200

250

300

350

Tem

per

atu

re(°

C)

Speed Current 90 g/cft Pt New Pt-Pd 4:1 70 g/cft Temp.

Light-Duty studies

Laboratory EDC simulation results –CO aged (HT800/20h)

0

20

40

60

80

100

120

0 200 400 600 800 1000 1200

Con

vers

ion

(%)/

Sp

eed

(km

/h)

0

50

100

150

200

250

300

350

Tem

pera

ture

(°C

)

Speed Current 90 g/cft Pt New Pt-Pd 4:1 70 g/cft Temp.

Light-Duty studies

Light-off Test Results at Different Temperatures

111

139

193 20

5

87

181

184

17718

7 206

211 22

6

173 18

9

189

182

0

50

100

150

200

250

Fresh HT-600°C

HT-700°C

HT-800°C

Fresh HT-600°C

HT-700°C

HT-800°C

Tem

per

atu

re,°

C

CO THCCurrent Pt-only /90 g/cft New Pt-Pd 4:1/ 70 g/cft

Light-Duty studies

Catalyst Characterization: High resolution SEM-EDS

Current Pt-only / HT-800°C/20h aged

New Pt-Pd / Fresh

Current Pt-only / Fresh

New Pt-Pd/ HT-800°C/20h aged

Current Pt-only / HT-800°C/20h aged

New Pt-Pd / Fresh

Current Pt-only / Fresh

New Pt-Pd/ HT-800°C/20h aged

Catalyst Characterization

d=39.835

d=46.402 d=66.846 d=67.775

d=81.500

d=86.051

d=39.835

d=46.402 d=66.846 d=67.775

d=81.500

d=86.051

O

Al

Pd

Pt

O

Al

Pd

Pt

EDS- analysis XRD-analysis

Pt and Pd interact: By forming an alloy

Slows down sintering

Stabilizes Pt

Increases durability

SO2 resistance –Lab EDC simulation with E4 mixture

0,248

0,051

0,256

0,052

0

0,05

0,1

0,15

0,2

0,25

0,3

THC CO

Em

issi

ons

(g/K

m)

Current Pt-only, 90 g/cft New Pt-Pd, 4:1, 70 g/cft

25 ppm SO2HT ageing (400°C / 20h)

Light-Duty studies

PGM price comparison

Price estimate based on PGM prices of 4th quarter 2008 in €

61

40

0

10

20

30

40

50

60

70

Pt only/ 90 g/cft Pt:Pd/ 4:1/ 70 g/cft

Rel

ativ

eP

GM

pri

ces

Heavy Duty Studies

Engine Bench Testing On-Road Ageing

Engine: Calibrated to Euro IIIAgeing cycle: 35000 Km on roadCatalyst: 30 g/cft Pt:Pd (4:1) coatedon EcoCat® substrate

Performance at different test points:- conversion of THC, CO, formation of NO2

Test vehicle:MAN 6.9 l Turbo (D 0826 LOH 17), 166 kW (2400 1/min, 664 Nm)Fuel: city Diesel 8 ppm Sulfur

Bench Engine tests using MAN engine

42 560

289

220

200

1200

Low1

666252384Exhaust gas, m3/h

9800037 00056 500SV, 1/h (6,79 dm3)

440370280Temp., °C

546400207Torque, Nm

215012001800Engine speed, rpm

HighMediumLow2Test point

42 560

289

220

200

1200

Low1

666252384Exhaust gas, m3/h

9800037 00056 500SV, 1/h (6,79 dm3)

440370280Temp., °C

546400207Torque, Nm

215012001800Engine speed, rpm

HighMediumLow2Test point

Heavy Duty Studies

Engine tests - MAN THC conversion

THC conversion as fresh (Average of 2-4 repeats)

0

20

40

60

80

1 00

Co

nv

ers

ion

,%

L o w 1 L o w 2 M e d iu m H ig h

C u rre n t/P t/ 40 g /cft N e w /P t-P d 4 :1 / 30 g /cft

%

Heavy Duty Studies

•THC conversion after 15h (Average of 2-4 repeats)

Engine tests - MAN THC conversion

•THC conversion after 35000 Km On-road ageing (Average of 2-4 repeats)

0

2 0

4 0

6 0

8 0

10 0

Co

nv

ers

ion

,%

L o w 1 L o w 2 M e d iu m H ig h

C u rre n t/P t/ 40 g /c ft N ew /P t-P d 4 :1 / 3 0 g /c ft N ew /P t-P d , 4 :1 /3 0 g /c ft, 3 50 00 K m

%

Heavy Duty Studies

NO2 formation as fresh (Average of 2-4 repeats)

Engine tests - MAN NO2 formation%

0

20

40

60

80

100

Fo

rma

tio

n,

%

L o w 1 L o w 2 M ed iu m H ig h

C u rren t/P t/ 40 g /c ft N e w /P t:P d 4:1 / 3 0 g/c ft

Heavy Duty Studies

NO2 formation after 15 h (Average of 2-4 repeats)

NO2 formation after 35000 Km On-road ageing (Average of 2-4 repeats)

Engine tests - MAN NO2 formation

0102030405060708090

100

Fo

rmat

ion

,%

Low1 Low2 Medium High

Current/Pt/ 40 g/cft New/Pt:Pd 4:1/ 30 g/cft New/Pt-Pd, 4:1/ 30 g/cft, 35000Km

Heavy Duty Studies

Summary

Pt and Pd form an alloy which has different sintering behaviorthan Pt or Pd separately

Pd helps to improve durability by allowing Pt to sinter slowly

Pd helps to keep light-off low after ageing

Combined with proper engine calibrations Pt-Pd catalyst is abetter candidate than classic Pt-only catalysts

NO2 formation decreases indicating its dependence to the Ptloading