Diesel Oxidation Catalyst (DOC)
System for PM Control
Satoshi Sumiya
Yasunori Imada
Johnson Matthey Japan, Environmental Catalyst and Technologies
1
Presentation Outlines
• Background
* Social requirements in Japan
* Importance to develop robust PM control technology
for in use diesels
• Experimental Procedure
• Test Results
1. Impact of DOC on PM Emission (work with Kawasaki)
2. Impact of DOC on Unregulated Hydrocarbons (work with TMG)
3. Newly Developed DOC + CSF (Catalysed Soot Filter) Using
Ceramic Foam
• Conclusions
2
1
Comparison of Diesel Emission
Control Technologies
++ : very good, + : good, - : not suitable
Emission Reduction Capability
S
tolerance
Practical
possibility
CO
THC
PM
NOx
DOC
++
++
+
-
++
++
Fuel Additive + DPF
+
+
++
-
++
+
Lean NOx catalyst
++
++
+
+
+
-
NOx trap
++
++
+
++
-
-
CR-DPF (CRTTM )
++
++
++
-
-
+
SCR
++
++
+
++
++
-
CRT + SCR (SCRTTM)
++
++
++
++
-
-
3
Legislation for In-Use HDD Enforced
by Tokyo Metropolitan Government
0.8
1994 standard
PM emission (g/kWh)
0.7
-60%
0.6
-70%
0.5
Tokyo Local regulation value
for in-use diesels
0.4
0.3
-30%
0.2
0.1
0
1996
Emission standard
for newly registered vehicle
1998
2000
2002
2004
2006
2008
4
2
Past and Future NOx and PM Legislations
0.8
US
EU
JP
CARB_BUS
NOx/ PM=10
NOx/ PM=20
NOx/ PM=50
0.7
0.6
PM g/kWh
0.5
NOx/PM
NOx/PMratio
ratioon
onin
inuse
usediesels
dieselsin
in
Japan
Japanare
arearound
around10
10to
to20.
20.
1996
NOx/ PM=10
0.4
0.3
2004
0.2
2007?
0.1
0.0
NOx/ PM=20
1999
2008
0.0
2005
1.0
2008
2.0
2000
2004
2003
2007
3.0
1998Bus
2000
ULEV(Nox+HC)
2005
4.0
1998Truck
5.0
6.0
NOx/ PM=50
7.0
NOx g/ kWh
5
How to Improve ? -DOC + CSF System Principle-
6
3
Temperatures Conditions During
Low Temperature Cycle
270
o
Temperature ( C)
250
230
210
190
Temperature Before Catalyst
170
Temperature After Catalyst
Temperature After Filter
150
0
60 120 180 240 300 360 420 480 540 600 660 720 780 840 900 960
Time (s)
Ref : R. Allansson et.al., SAE Paper 2002-01-0428
Low Temperature Cycle (40 hrs)
Performance in MK1 Fuel
Back Pressure (mbar)
160
Bare Filter Alone
140
CSF Alone
120
CRT
100
DOC + CSF
80
60
40
20
0
0
5
10
15
20
25
30
35
40
45
Time (Hours)
Ref : R. Allansson et.al., SAE Paper 2002-01-0428
8
4
Experimental Conditions
*Less than 50 ppm S fuel was used for all test.
Test 1 : Collaboration work with Kawasaki-city.
Test 2 : Collaboration work with Tokyo metropolitan Research Institute for Environmental Protection.
Vehicle/Engine
DOC
CSF
Size
(mm)
Cell
density
(cpsi)
Pt
(g/L)
Memo
2.6
D:267
X
L:305
200
0
Non-coat
Cordielite
Wall-through
2.6
OD:240
X
ID:120
X
L : 200
30 cpi
0.7
Catalyzed
Cordielite
foam filter
Vehicle
type
Engine
size (L)
Size
(mm)
Cell
density
(cpsi)
PGM
(g/L)
Test
1
Garbage
truck
5
D:191
X
L:178
400
2
Test
2
City
bus
10
D:267
X
L:152
400
13
D:267
X
L:152
Test
3
Engine
Bench
400
9
Specifications of Tokyo Metropolitan City Bus
Vehicle Specifications
Engine Maker
Hino
Engine Type
M10U (DI, 6 cylinders)
Engine Displacement
9.88 L
Maximum Power
230 PS / 2500 rpm
Maximum Torque
70 kgm / 1500 rpm
Registration
Feb.,1993 (HT2MLA41043)
10
5
Tokyo City Mode 2, 5, 8 and 10
80
Tokyo City Mode #2
Average speed : 8.4 km/h
60
Vechicle speed / km/h
Vechicle speed / km/h
80
40
20
40
20
0
0
200
60
80 0
400 600 800 1000 1200
Tokyo City Mode #8
Operation
time /: sec
Average speed
28.5 km/h
Vechicle speed / km/h
80 0
Vechicle speed / km/h
Tokyo City Mode #5
Average speed : 18.0 km/h
60
40
20
0
200
400
600
800 1000 1200
Operation time / sec
60
40
20
Tokyo City Mode #10
Average speed : 44.4km/h
0
0
0
200 400 600 800 1000 1200
200
400
600
800
1000 1200
Operation time / sec
Operation time / sec
11
Temperature Frequency
on Tokyo City Modes
50
50
>300C : 5%
20
10
180
220
260
300
340
380
420
460
>300C : 32%
10
5
0
180
220
260
300
340
380
420
460
Temperature at the inlet of DOC / C
500
40
30
>300C : 19%
20
10
200
500
Tokyo City Mode #8
Temperature at the inlet of CRT / C
15
Frequency / %
30
0
20
Frequency / %
Tokyo City Mode #5
40
180
220
260
300
340
380
420
460
500
Tokyo City Mode #10
Frequency / %
Frequency / %
Tokyo City Mode #2
Temperature at the inlet of CRT / C
15
>300C : 74%
10
5
0
180
220
260
300
340
380
420
460
Temperature at the inlet of DOC / C
500
12
6
Engine Map Points with Weighting Factor
on Japanese D13 Mode
100
Engine Load / %
80
60
40
20
0
0
20
40
60
80
100
Engine Speed / %
13
Test Results
- PM reduction Efficiency over DOC -
14
7
PM Reduction Efficiencies on DOC over
Kanagawa-Prefecture Modes
0.4
Conventional
DOC testing on
Garbage Truck
PM emission / g/km
Engine base
W ith DOC
0.3
(5L engine)
- 63%
0.2
- 52%
0.1
0
1
Low speed
mode
(Average : 12.65 km)
2
High speed mode
(Average : 24.1 km)
15
Emitted Carbonacious Matter over
Kanagawa-Prefecture Modes
Emitted carbonacious matter / g/km
0.4
Garbage Truck
EC
0.3
0.2
(5L engine)
OC
- 95%
- 95%
0.1
0
Engine base
With catalyst
Low speed mode
(Average : 12.65 k m)
Engine base
With catalyst
High speed mode
(Average : 24.1 k m)
16
8
Emitted PAHs and Benzo-(a)-Pylene over
Kanagawa-Prefecture Modes
3.0
Engine base
Emitted PAHs / ug/km
140
With catalyst
120
100
- 78%
80
60
- 63%
40
Emitted Benzo-(a)-pylene / ug/km
160
Engine base
With catalyst
2.5
2.0
- 61%
1.5
- 77%
1.0
0.5
20
0.0
0
Low speed
1
High speed
Low speed mode
High speed mode
(Average : 12.65 km)
(Average : 24.1 km)
2
Low speed mode
(Average : 12.65 km)
High speed mode
(Average : 24.1 km)
17
Unregulated Hydrocarbons Reduction
Efficiencies over Tokyo City Modes
100
Reduction efficiency / %
Reduction efficiency / %
* City Bus test : 10L engine
80
60
Formaldehyde
40
20
100
80
60
40
Acetaldehyde
20
0
Mode #2
Mode #5
Mode #8
Mode #10
80
60
40
1, 3-Butadiene
20
0
Reduction efficiency / %
Rreduction efficiency / %
0
100
100
Mode #2
Mode #5
Mode #8 Mode #10
80
60
40
Benzene
20
0
Mode #2
Mode #5
Mode #8 Mode #10
Mode #2
Mode #5
Mode #8
Mode #10
18
9
Vehicle Test Summary
1. DOC installed on garbage truck can reduce more than 40%
PM. The reduction efficiency depends upon the vehicle
driving condition.
2. DOC mainly reduced organic carbons (SOF) into PM and
no effective function to reduce elementary carbons (Soot).
3. DOC effectively reduced many kinds of unregulated
hydrocarbons at various driving condition.
19
- PM reduction Efficiency over DOC + CSF -
20
10
How to Improve ?
[PM combustion rate] ≦　[PM
accumulation rate]
≧
Increase NOx concentration
Reduce PM emissions
（Out of control)
（Out of control)
Low efficiency filter
Improve temperature condition
（Wire mesh, Foam type)
（Dual skin tube)
Catalyzed filter
（Pt base catalyst)
21
System Concept of DOC+CSF Using Foam
Filter
1. Use NO many times in the unit
Frame by frame reaction of NO2 with C
2. Larger geometrical surface area (GSA) than wall-through type
DPF, and can increase number of contact point with PM
Foam filter
#30
GSA(cm2/cm3)
43
Wall-through filter
12/200 8/300
9
12
3. Acceptable backpressure level as CSF
22
11
Pt
NO2 Reaction with C in Coated Foam Filter
Soot
* Frame by Frame Reaction of NO2 with C
Frame
NO2
NO
NO+CO2
NO2
NO2
NO
NO+CO2
NO2
23
Outward of Cordielite Ceramic Foams
#6
#20
#13
#30
24
12
Plate Stack and Cylindrical Design
IN
IN
Plate stack Type
Cylindrical Type
Efficiency
High
Low(in parallel)/High(in series)
D.Pressure
High
Low
Canning
Difficult
Easy
(Mechanical strength)
25
PM Emissions over D13 mode
2.0
PM weight over D13 mode / mg
1.8
SOF
Soot+Sulfates
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
1
Engine base
2
3
4
With
DOC + Foam filter
(OD240 X ID90, 20 cpi)
26
13
PM mass over TMG mode#5 / mg
PM Emissions over Tokyo City Mode #5
- Blow-Off Effect while Transient Test 1
0.8
Soot
0.6
SOF
-43%
0.4
0.2
0
DOC
With DOC
+ Foam filter
(OD240 X +
ID90, 20 cpi)
Engine out
CSF
27
PM Emissions over D13 Mode and Tokyo
City Mode#5
0.8
TMG#5 mode
-56 %
-45 %
0.4
-44 %
0.6
-37 %
PM Emission / g/kwh
D13 mode
0.2
0.0
Engine out A: OD240 X ID90 Engine out
B
A: OD240 X ID90
28
14
Conclusions
1. DOC can reduce part of the PM, especially organic carbons. The
reduction efficiency depends upon the SOF content and
temperature at driving condition.
2. DOC effectively reduced unregulated hydrocarbons emitting
from diesel engines. This is additional advantage to use DOC, not
only for reducing PM mass.
3. System performance of newly developed DOC + catalyzed foam
filter was demonstrated and showed promising results.
* On this system, around 50% PM reduction efficiency was
confirmed on both steady state mode and transient modes.
* This system enable to cover the specific PM reduction target in
between DOC and conventional wall-through DPF.
29
Acknowledgments
•
Tokyo Metropolitan Research institute for Environmental
Protection is acknowledged for permission to make
presentation and for help with the testing.
•
Environmental Protection Bureau, Pollution Control
Department, Automobile Policy Section in Kawaski-City,
Kanagawa-prefecture is acknowledged for permission to
make presentation and for help with the testing.
•
Bridgestone Corporation is acknowledged for permission to
make presentation and for help with the supplying foam
filters.
30
15
Thank you !
31
16