deer07_shoji.pdf (2.42 MB)

TOYOTA 12007 Diesel Engine-Efficiency and Emissions Research (DEER) Conference

An Improvement of Diesel PM and NOx Reduction System

Akira Shoji 14 Aug. 2007

TOYOTA MOTOR CORPORATION

2

TOYOTA2007 Diesel Engine-Efficiency and Emissions Research (DEER) Conference 2

Contents 1. Current status of DPNR

2. Improvement of NOx storage and reduction efficiency (a) How to realize effective rich condition

- Rich combustion - Multiple injection - Additional fuel injection

(b) How to maintain activated state - Improvement on thermal deterioration - Improvement on sulfur poisoning New concept DPNR

(c) How to treat unexpected products - Clean-up catalyst (including NOx slightly reduced)

3. Future prospective of the next generation DPNR

4. DPNR(NSR) or UREA-SCR ?

3


Current Status of DPNR NSR Catalyst - NSR (NOx Storage Reduction Catalyst) - LNT (Lean NOx Trap)

1992 Patent application 1994 Start of production 2003 Start of diesel engine application : DPNR

Lean condition Rich condition

Storage of NOx

NO O2 NO2+O*Pt

SubstrateSubstrateReduction of NOx

HC CO

H2ON2

NOO* CO2

Pt SubstrateSubstrate

NOx purification mechanism of NSR

NOx Storage material

4

1


Introduction of DPNR

Wide scale introduction (EU-wide)

Field trial

st Introduction (for selected countries)

2002 2003 2004 2005

Clean power concept (Paris show) 60 cars, 7 countries

2006 2007

low sulfur diesel fuel

5


40,000

100,000

20,000

0

03 04 05 06

60,000

80,000

Year

Prod

uctio

n vo

lum

e (u

nits

) Production Volume of DPNR

6









7


(a)How to Realize Effective Rich Condition

zSmokeless rich combustion Very high NOx conversion efficiency by CO CO emitted from catalyst under rich condition Very limited operation area

zMultiple injection High NOx conversion efficiency by CO Limited operation area by smoke and oil dilution Fuel economy

Comparison of three methods In cylinder

On catalyst

++ -

+

+ ++

--

-

Air Fuel ratio Stoichiometric

CO

, HC

Smok

e, N

Ox SmokeCO,HC

NOx

Smoke less rich combustion

Pilot Main After

around 30 to 40 deg.after TDC

Multiple injection

-

zAdditional fuel injection High NOx conversion efficiency by local rich condition on the catalyst No limitation of operation area Additional injector

8


Methods for Rich Pulse

DPNR catalystto exhaust manifold

#4 Exhaust port Exhaust port injection

Exhaust pipe injection

Additional fuel injection system

Intake air

NSR catalyst DPNR catalyst

Exhaust gas

Exhaust pipe injector

Exhaust portinjector

9


Key Technologies for Rich Pulse

Air-Fuel Ratio : Calculated

250 0

500 750

0 10 20

25 30

20 15 10

12 14

10 8 6

Time (s)

NO

x (p

pm)

Fuel added Air-Fuel Ratio after Catalyst

CO2

NOx

Air-

Fuel

Rat

io

CO

2 (%

)

Fuel added Air-Fuel ratio after catalyst

Air-

Fuel

ratio

25 30

20 15 10

12 14

10 8 6 C

O2

(%)

250 0

500 750

NO

x (p

pm) CO2

NOx

Simple increase of additional fuel is not favorable.

Short rich pulse duration Low NOx reduction efficiency

Extended rich pulse duration (0.3 1.0sec.)

Increased quantityof additional fuel Higher NOx reduction efficiency Increased fuel penalty

+ -

-

1.0 sec.

0.3 sec.

10


Key Technologies for Rich Pulse Effect of multiple injection by additional fuel injection

Deeper rich pulse Higher NOx reduction Higher HC emission

Multiple rich pulse High NOx reduction Lower THC emission

Injection Signal

ON

OFF

ON

OFF

0 1Time (relative)

Single injection Triple injection

Stoichiometric air-fuel ratio

Engine speed : 2000rpm BMEP : 0.63MPa

Air-

Fuel

ratio

1 4 Divided number of additional fuel injection

NOx conversion ratio

THC

Con

cent

ratio

n(R

elat

ive)

0

0.5 1.0

THC

Engine speed : 2000rpm BMEP

: 0.63MPa

NO

x co

nver

sion

ratio

(%

)

100 95 90

32

+ -+ +

11


Key Technologies for Rich Pulse Advantage of low space velocity

Low SV can prolong rich pulse duration and results in lower NOx and HC emission

Injection of additional fuel 30

20

10 Air-

Fuel

ratio

afte

r cat

alys

t

0

400

800

NO

x(pp

m)

0

400

800

THC

(ppm

)

0 60 30 Time(sec.)

Lower Space Velocity

NOx inflow NOx THC

Air-Fuel ratio

12









13


Improvement on Thermal Deterioration

20

0

30

Ave

rage

siz

e of

Pt m

etal

par

ticle

(nm

)

10

Pt/CZYPt/Al2O3

before aging after aging

Measured by the low temp. CO pulse method Aging condition:800 deg.C x 5hours

Support

Pt Support : -Al2O3

Support : CZY(CeO2-ZrO2-Y2O5 solid solution)

Pt particles on ceria-basedcatalysts do not sinter at all.

Pt-Support interaction (Pt-O-Ce)is the key point for the inhibitionof Pt sintering.

Pt Pt

Ce O

Ce O

Support

Pt

SAE 2006-01-0413

Effect of support material of TWC for sintering of Pt.*TWC:three way catalyst*

14


An example of incompleteness of sulfur regeneration of NSR catalyst

Improvement of Sulfur Poisoning

Sulfu

r poi

soni

ngam

ount

(Rel

ativ

e)

Outer

Center Re

arFron

t

1.6

1.2

0.8

0.4

0.0

Exhaust gas flow

Incompleteness of sulfur-regeneration

15


One of New Concept DPNR (S Trap DPNR)

Sulfur trap catalyst DPNR catalyst

Sulfur free exhaust gas

Exhaust gas

S Trap DPNR

Amount of passed sulfur (g/L) 0 10 20 30

Am

ount

of s

tore

d su

lfur (

g/L)

Model gas test SV:50000/h, Temp.:450deg.C const. Fresh catalyst

0

10

20

30

Sulfur poisoning of DPNR catalyst with sulfur trap catalyst

Sulfur trap catalyst

Concept of S Trap DPNR

Sulfur poisoning of the DPNRcatalyst is suppressed.

Thermal deterioration caused by sulfur discharging controlcan be reduced.

DPNR catalyst

16

Basic deteriorationpattern of DPNR

70%80%

43%

Japanese JC08hot test cycle


One of New Concept DPNR (S Trap DPNR) Results of durability test

0 2 4 6 8 10 NO

x co

nver

sion

effi

cien

cy (%

)

Mileage accumulation ( x10,000 km)

0

20

40

60

80

100 0 20

Total inflow of sulfur (g/L catalyst) 10 30

Japan JC08 hot test cycle

Improvementof S trap catalyst

Improvement of DPNR catalyst

Decrease sulfur inflow from fuel from lubricant oil fuel consumption

17









18


Clean-up Catalyst for DPNR

Clean-up catalyst

NSR catalyst DPNR catalyst

Exhaustgas

Regeneration from sulfur poisoning

NOx storage material

HC CO H2 SO3

SO2


H2S, HC, CO SO2, H2O, CO2 H2S emitted during sulfur regeneration

control can be converted to SO2

(NOx slightly reduced)

NO, HC, CO NH3 N2, H2O, CO2

NOx reduction

NOx storage material NOx is slightly reduced by NH3 and HC

HC CO H2

H2ON2

NO

CO2


......

19









20


Future Prospective of Next Gen. DPNR

PGM loading amount much

60

40

20

0

80

100

NO

x co

nver

sion

rat

io (%

)

1st gen.DPNR1st gen.DPNR

New European Driving Cycle

Next gen.DPNR

little

21









22DPNR(NSR) or UREA-SCR ? advantage

Installation for PC and LDT

Fuel consumption penalty

Desulfurisation

Urea supply infrastructure

System cost

Choice

Maintenance

Low sulfur fuel Loading quantity of PGM

Anti tampering

NOx purification performance DPNR (=NSR)

NOx reduction,Desulfurization

Needed periodicaldesulfurisation

PC, LDT

for PC

23


DPNR(NSR) or UREA-SCR ?

Engine swept volume (= Vehicle weight )

Syst

em C

ost

Critical point affected by - raw emission level from engine

- performance of catalyst- price of PGM- price of Urea dosing system

DPNR advantage DPF+Urea-SCR advantage

Large V8 engine for SUV

Small L4 engine for compact car

DPF + Urea-SCR

DPNR Amoun

t of PGM Incre

ase

24


Conclusions

NOx reduction High reduction efficiency of additional fuel injection system can be

realized by multiple injection and/or lower space velocity with low HC emission and fuel consumption.

Catalyst improvement Ceria based support is effective for suppression of thermal deterioration. S-trap DPNR will be one of the promising system which can restrain the

deterioration by sulfur poisoning.

1.For the improvement of NOx storage and reduction efficiency

2. Future prospective of the next generation DPNR It will be able to realize over 70% of NOx purification ratio with less PGM

in the next generation DPNR.

3. DPNR(NSR) or UREA-SCR ? We should choose DPNR(NSR) for smaller engines of swept volume and

Urea-SCR for larger ones.

25


Thank you for your attention

1VD-FTV 4.5L V8 Just Introduced!

2AD-FHV 2.2L L4 w/DPNR

26


TOYOTA Diesel Clean Advanced Technology system

Low emission

Low fuel consumption

High power & torque

Engine management

Fuel Injection System New generation CR injection systePiezo Injector High pressure injection 1800bar-Multiple injection

Combustion Low compression ratio Smokeless rich combustion High efficiency EGR cooler

and temperature control

After treatment DPNR Original DPNR caralyst Exhaust port/pipe injector DPF

TOYOTA DTOYOTA D--CATCAT

27


DPNR (Diesel Particulate-NOx Reduction System)

Exhaust gas

PM

NOx storage reduction catalyst

Exhaust gasFilter substrate

DPNR catalyst

Application for current 2AD-FHV engine Configuration of DPNR catalyst

28(b) How to Maintain Activated State Degradation of NOx storage capability

1.2

1.0

0.8

0.6

0.4

0.2

0

Thermal degradation

Sulfur poisoning

0 5 10 15 20 Mileage accumulation ( x10,000 km)

NOx storage capability is Decreased by thermal deterioration and sulfur poisoning

NO

x st

orag

e ca

pabi

lity

(rel

ativ

e)


29


Improvement on Thermal Deterioration

SAE 2006-01-0413

1.2

1.0

0.8

0.6

0.4

0.2

0 0 300 500200 400100

Diameter of Pt Particle()

NO

x st

orag

e ca

pabi

lity

(rel

ativ

e)

Relation between NOx storage capability and sintered Pt diameter

Pt particle sintering : Main cause of deactivation

Alumina Support

Pt

Alumina Support

Pt (a few nm)

30


Improvement of Sulfur Regeneration Fuel injection

NSR NOx storage/reduction Raise gas/catalyst temp.

Exhaust gas

DOC Raise gas/catalyst temp.

NSR NOx storage/reduction

Exhaust gas

Fuel injection

DPNR

DPNR

An Improvement of Diesel PM and NOx Reduction SystemContentsCurrent Status of DPNRIntroduction of DPNRProduction Volume of DPNRContents(a)How to Realize Effective Rich ConditionMethods for Rich PulseKey Technologies for Rich PulseKey Technologies for Rich PulseKey Technologies for Rich PulseContentsImprovement on Thermal DeteriorationImprovement of Sulfur PoisoningOne of New Concept DPNR (S Trap DPNR)One of New Concept DPNR (S Trap DPNR)ContentsClean-up Catalyst for DPNRContentsFuture Prospective of Next Gen. DPNRContentsDPNR(NSR) or UREA-SCR ?DPNR(NSR) or UREA-SCR ?ConclusionsThank you for your attentionTOYOTA Diesel Clean Advanced Technology systemDPNR (Diesel Particulate-NOx Reduction System)(b) How to Maintain Activated StateImprovement on Thermal DeteriorationImprovement of Sulfur Regeneration

Documents

deer07_shoji.pdf (2.42 MB)