DEER. Emission Control Technologies August 4 th , 2009. Dearborn, MI Investigation on continuous soot oxidation and NOx reduction by SCR coated DPF Phillip Bush, Eminox Svetlana Iretskaya , Catalytic Solutions, Inc. Ted Tadrous, Engine Control Systems
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DEER. Emission Control TechnologiesAugust 4th, 2009. Dearborn, MI
Investigation on continuous soot oxidation and NOx reduction by SCR coated DPF
Phillip Bush, EminoxSvetlana Iretskaya, Catalytic Solutions, Inc.Ted Tadrous, Engine Control Systems
DEER. Emission Control TechnologiesAugust 4th, 2009. Dearborn, MI 2
Outline
•
Requirements for combined SCR-DPF catalyst•
Evaluation of CSI catalyst for NOx
removal and soot oxidation
•
Engine tests on continuous soot oxidation and NOx
reduction by combined SCR-DPF•
Summary
DEER. Emission Control TechnologiesAugust 4th, 2009. Dearborn, MI 3
SCR-DPF. Two Functions: NOx
reduction and Soot oxidation
SCR with ammonia (urea)
4NO + 4NH3
+ O2
4N2
+ 6H2
O (standard SCR
reaction)NO + NO2
+ 2NH3
2N2
+ 3H2
O (fast SCR reaction)
NO + ½
O2
→ NO2
6 NO2
+ 8 NH3
→7 N2
+ 12 H2
O (slow SCR reaction)
SOOT OXIDATION
C + O2 CO2
C + ½
O2
CO
C + NO2
CO + NO
C + 2 NO2
CO2
+ 2NO
Urea Injector
SCRDPF/CDPF
Urea Injector
SCRDPF/CDPF
C
Urea Injector
SCR-DPFC
Urea Injector
SCR-DPFC
Urea Injector
SCR-DPF
DEER. Emission Control TechnologiesAugust 4th, 2009. Dearborn, MI 4
CSI SCR catalysts activity on Flow-Through substrates More than 90% NOx reduction
DTA: SCR with NO2TG: SCR with NO2DTG: SCR with NO2
363 C
425 C Soot Oxidation with LT-SCR catalyst:
with NO2
in feedgas peak of oxidation: 425 oC
without NO2
in feedgas peak of oxidation: 433 oC
425oC
433oC
Catalytic Soot oxidation had been observed with and without NO2
in feed gas.
DEER. Emission Control TechnologiesAugust 4th, 2009. Dearborn, MI 7
Balance Point Temperature Test (@ ECS) No urea injection. 5.9L engine. 14L SCR-DPF.
4 grams/lit Soot Loading - Cummins ISB 5.9 - ULSD
100
150
200
250
300
350
400
450
500
Exh
Tem
p [d
eg-C
]
0.02
0.03
0.04
0.05
0.06
0.07
0.08
SBP
["H
2O/a
cfm
]
Temperature - Pre Muffler SBP
BPT ~ 300 oC
> 90% soot regeneration ~ 440o
DEER. Emission Control TechnologiesAugust 4th, 2009. Dearborn, MI 8
SCR-DPF: NOx
Reduction and Soot oxidation
•
CSI Low-temperature SCR catalyst showed –
good SCR activity at various conditions and –
also soot oxidation properties:•
TG/DTA –
lowering peak of soot oxidation by > 200 oC•
Balance Point Temperature on engine test was found to be around 300 oC (in presence of NO2
)
•
Big Question: would LT-SCR catalyst keep SCR and Soot oxidation properties simultaneously?
•
Questions addressed in the current study:–
does presence of soot on filter affect SCR performance–
does urea-injection affect soot oxidation properties–
does NO2
concentration limit SCR or soot performance
DEER. Emission Control TechnologiesAugust 4th, 2009. Dearborn, MI 9
Test Set Up (@ Eminox)
Test substrate
Injection
~ 1000mm
Fully insulated pipeworkall test system
2 3 400mm 400mm
4
min 800mm
1. NOx, NO,NO2, T, P static (emissions measured with CL)2. Adblue injection rate3. T, P static, exh flow rate4. T, P static, NOx, NO, NO2, NH3 (emissions measured with FTIR)
<7
1200mm
1
10.5x6 Oxicat
> 500mm
Bleed off valve for flow control
Mixer
10.5x12 Filter
To silencer
Valve to control
NO/NO2 ratio
Test substrate
Injection
~ 1000mm
Fully insulated pipeworkall test system
2 3 400mm 400mm
4
min 800mm
1. NOx, NO,NO2, T, P static (emissions measured with CL)2. Adblue injection rate3. T, P static, exh flow rate4. T, P static, NOx, NO, NO2, NH3 (emissions measured with FTIR)
<7
1200mm
1
10.5x6 Oxicat
> 500mm
Bleed off valve for flow control
Mixer
10.5x12 Filter
To silencer
Valve to control
NO/NO2 ratio
Set up enables to control:-
temperature, -
flow rate, -
injection stoichiometry- NO/NO2
ratio
Engine: Cummins N14 Eu2 525 hp
SCR-DPF: CS-585 on 9”x12”
300/12 high-
porosity cordierite
DEER. Emission Control TechnologiesAugust 4th, 2009. Dearborn, MI 10
Example of a Test on soot loaded SCR-DPF (340oC; 35Khr-1; NO2
/NOx
= 0.3, 4.9 g/L soot) NOx
conversion; Ammonia slip; ANR
T=340C.SV=35K. NO2/NOx = 0.3
0
10
20
30
40
50
60
70
80
90
100
0 5 10 15 20 25Time (min)
Am
mon
ia s
lip (p
pm) N
Ox
conv
ersi
on,
%
-0.1
0.1
0.3
0.5
0.7
0.9
1.1
1.3
1.5
AN
R
ConvNH3_outANR
97.6%
DEER. Emission Control TechnologiesAugust 4th, 2009. Dearborn, MI 11
Details of a test on soot loaded SCR-DPF (340oC; 35Khr-1; NO2
/NOx
= 0.3, 4.9 g/L soot) NO,NO2
–
inlet and outlet; ANRT=340C, SV=35K
0
200
400
600
800
1000
1200
1400
1600
1800
5 15 25 35 45 55Time, min
Tem
pera
ture
(deg
C) N
O, N
O2
(ppm
)
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
AN
R
NO In NO Out
NO2 in NO2 Out
Temp Cat-In ANR - -
Switched both analysers
to downstream locationto check correlation
DEER. Emission Control TechnologiesAugust 4th, 2009. Dearborn, MI 12
Details of a test on soot loaded SCR-DPF (@ Eminox) (340oC; 35Khr-1; NO2
/NOx
= 0.3, 4.9 g/L soot) NO,NO2
outlet; Backpressure
T = 340 C; SV=35K; NO2/NOx=0.3
3
3.5
4
4.5
5
5.5
6
6.5
7
7.5
8
10 20 30 40 50 60Time (min)
dP (k
Pa)
0
150
300
450
600
750
900
1050
1200
1350
1500
NO
x (p
pm)/T
empe
ratu
re (d
egC
)
dPNO OutNO2 OutTemp
urea is injected
18% soot removal based on weight of
the filter
DEER. Emission Control TechnologiesAugust 4th, 2009. Dearborn, MI 13
SCR activity with and without soot No effect of soot was observed
0
100
200
300
400
500
600
700
800
900
1000
5 15 25 35 45
Time, min
NO
x (p
pm)
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
NO_in 5 g sootNO2_in 5 g sootNO_out 5 g sootNO2_out 5 g sootNH3_out 5 g SootANR
T = 310 oC, SV=32K hr-1, NO2
/NOx
= 0.5, 0 g sootT = 310 oC, SV=32K hr-1,
NO2
/NOx
= 0.5, 5.3 g soot
0
100
200
300
400
500
600
700
800
900
1000
0 10 20 30 40 50 60
Time, min
NO
x (p
pm)
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
AN
R
NO_in 0 g sootNO2_in 0 g sootNO_out 0 g sootNO2_out 0 g sootNH3_out 0 g sootANR
NO2
to NO conversion due to soot oxidation did not affect SCR performance –
the same high (>97%) NOx
conversion at 10 ppm NH3
was observed during the tests
DEER. Emission Control TechnologiesAugust 4th, 2009. Dearborn, MI 14
SCR activity with and without soot Monitoring Back Pressure
T = 310 oC, SV=32K hr-1, NO2
/NOx
= 0.5, 0 g sootT = 310 oC, SV=32K hr-1,
NO2
/NOx
= 0.5, 5.3 g sootT=300C, SV=32K, NO2/NOx=0.5, 5.3 g/L soot
7
7.5
8
8.5
9
9.5
10
10.5
11
11.5
12
10 15 20 25 30 35 40 45 50Time, min
dP (k
Pa)
0
200
400
600
800
1000
1200
1400
NO
x (p
pm)/T
empe
ratu
re (d
eC)
dPNO_outNO2_outT2
T=300K, 32K, 50%NO2, 0 g/L soot
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
0 10 20 30 40 50Time, min
dP (k
Pa)
0
100
200
300
400
500
600
700
800
900
NO
x (p
pm),
Tem
pera
ture
(deg
C)
dP kPaNO_out - ppmNO2_out - ppmT2 Cat-In degC
Soot oxidation was relatively low at these conditions –
BP lowered about 0.5 kPa
BP during 45 min of the test.
DEER. Emission Control TechnologiesAugust 4th, 2009. Dearborn, MI 15
Evaluating effect of NO2
/NOx
ratio SCR performance was not influenced by NO2
/NOx
ratio at 300oC
0
100
200
300
400
500
600
700
800
900
1000
5 15 25 35 45
Time, min
NO
x (p
pm)
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
AN
R
NO_in 5 g sootNO2_in 5 g sootNO_out 5 g sootNO2_out 5 g sootNH3_out 5 g SootANR
T = 310 oC, SV=32K hr-1, NO2
/NOx
= 0.5,
5.3 g sootT = 300 oC, SV=32K hr-1,
NO2
/NOx
= 0.3,
4.6 g soot
Competition for NO2
between soot oxidation reaction and SCR reaction did not affect SCR performance –
the same high NOx
conversion (>98% at 10 ppm ammonia slip) was observed during the tests
DEER. Emission Control TechnologiesAugust 4th, 2009. Dearborn, MI 16
Evaluating effect of NO2
/NOx
ratio Soot oxidation –
no clear effect
T=300C, SV=32K, NO2/NOx=0.5, 5.3 g/L soot
7
7.5
8
8.5
9
9.5
10
10.5
11
11.5
12
5 10 15 20 25 30 35 40 45 50Time, min
dP (k
Pa)
0
200
400
600
800
1000
1200
1400
NO
x (p
pm)/T
empe
ratu
re (d
eC)
dPNO_outNO2_outT2
T = 310 oC, SV=32K hr-1, NO2
/NOx
= 0.5,
5.3 g soot50’
test: % soot removal –
n/aT=300C, SV=32K, NO2/NOx=0.3
8
8.5
9
9.5
10
10.5
11
11.5
12
12.5
13
30 35 40 45 50 55 60 65 70Time (min)
dP (k
Pa)
0
200
400
600
800
1000
1200
NO
x (p
pm)/T
empe
ratu
re (d
egC
)
dP kPaNO_out - ppmNO2_out - ppmT2 Cat-In degC
T = 300 oC, SV=32K hr-1, NO2
/NOx
= 0.3,
4.6 g soot70’
test: 33.3% soot removal
Based on BP measurements no difference in soot oxidation had been observed at 300 C for both tests. Based on weight of the filter 33.3% soot was removed during 70 min of the test with 30% NO2
DEER. Emission Control TechnologiesAugust 4th, 2009. Dearborn, MI 17
Ammonia slip vs. NOx conversion for SCR-DPF More than 90% NOx