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Zeolite Supported Pd Catalysts for
Low Temperature NOx and HC storage
Hai-Ying Chen
Johnson Matthey Inc.
April 6, 2016
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1
• Challenges in controlling NOx and HC emissions at low temperatures
• Development of zeolite supported Pd catalysts for low temperature
NO/HC storage and conversion
• Characterization of the active sites in zeolite supported Pd catalysts
• Fully formulated catalysts with zeolite supported Pd catalysts
• System demonstration on vehicles
• Modelling study
Outline
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2
• Challenges in controlling NOx and HC emissions at low temperatures
• Development of zeolite supported Pd catalysts for low temperature
NO/HC storage and conversion
• Characterization of the active sites in zeolite supported Pd catalysts
• Fully formulated catalysts with zeolite supported Pd catalysts
• System demonstration on vehicles
• Modelling study
Outline
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3
Federal Tier 3 and CA LEV III emission standards
call for significant reduction of criteria pollutants
Tier 3 Certification Bin Standards
(FTP; 150,000 miles)
BinNMOG+NOx PM* CO HCHO
mg/mi mg/mi g/mi mg/mi
Bin 160 160 3 4.2 4
Bin 125 125 3 2.1 4
Bin 70 70 3 1.7 4
Bin 50 50 3 1.7 4
Bin 30 30 3 1.0 4
Bin 20 20 3 1.0 4
Bin 0 0 0 0 0
Federal Tier 3 standards California LEV III standards
www.dieselnet.com
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4
Fuel economy and Green House Gases (GHG) are also
part of the future emission legislations
Additional GHG limits:
N2O: 0.010 g/mile
CH4: 0.030 g/mile
US Worldwide
www.theicct.org
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5
Advanced engines can improve the fuel efficiency, but
result in lower exhaust temperatures
• Advanced combustion,
downsizing of engine,
turbocharging,
all result in lower exhaust
temperaturesGasoline
vehicles
Diesel
vehicles
• Diesel CO2 reduction
leads to even lower
exhaust temperatures
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6
Control of cold-start emissions is crucial to meet the
future emission regulations
• e.g. SULEV30 (HC +NOx = 30 mg/mile)• Current TWC, DOC, SCR, NAC catalysts function at >~200oC• ~100-200s for these components to reach the operating temp• Engine-out HC/NOx emissions exceed SULEV30 during the cold
start period
HC + NOx SULEV30
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7
Zeolite based HC traps can storage HC’s at low
temperatures, but release them too earlier
Zeolite
Zeolite/M1
Zeolite/M2
HC storage at 80C
1500ppm HC inlet
HC release
Temp ramping
rate 40C/min
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8
Conventional NACs store NO at LT but with low trapping
efficiency, oxidation of NO to NO2 is kinetically limited at LT
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9
• Challenges in controlling NOx and HC emissions at low temperatures
• Development of zeolite supported Pd catalysts for low temperature
NO/HC storage and conversion
• Characterization of the active sites in zeolite supported Pd catalysts
• Fully formulated catalysts with zeolite supported Pd catalysts
• System demonstration on vehicles
• Modelling study
Outline
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10
Laboratory evaluation protocol
� NO/HC storage, release, and conversion testing
Pre
con
dit
ion
ing
Sto
rag
e
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11
Zeolite supported Pd catalysts exhibit high NO storage
capacity with nearly 100% trapping efficiency
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12
Zeolite structures have a strong influence on the
temperature profiles of the NOx storage capacity
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13
Zeolite structures also affect the NOx release profiles
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14
Zeolite structures affect the HC storage and release profiles
– the larger the pores, the higher HC storage capacity
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15
• Challenges in controlling NOx and HC emissions at low temperatures
• Development of zeolite supported Pd catalysts for low temperature
NO/HC storage and conversion
• Characterization of the active sites in zeolite supported Pd catalysts
• Fully formulated catalysts with zeolite supported Pd catalysts
• System demonstration on vehicles
• Modelling study
Outline
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16
Pd is located at the exchange sites of the zeolite supports
IR spectra of 1%Pd/Zeolite (red) and bare zeolite (black) samples after dehydration
at 400 °C under 6%O2/Helium for 2 hours; (A) BEA, (B) MFI; (C) CHA
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17
CO adsorption experiments confirm that Pd is at the
exchange sites
Transmission spectra of CO adsorbed on Pd/Zeolites and Pd/Ceria
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18
Pd at the exchange sites adsorbs NO directly, other
non-zeolite supported Pd catalysts need formation of nitrates
Transmission IR spectra of NO adsorption on 1%Pd/CHA (red) and 1%Pd/Alumina (black)
[samples were dehydrated at 400 °C under 6%O2/Helium for 2 hours; spectra recorded
after 15 min exposure to 500ppm NO/Helium at 100°C]
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19
The presence of H2O has little impact on NO adsorption
on Pd sites
DRIFTS spectra recorded at 100 °C for Pd-CHA after exposure to
(NO + O2) with or without H2O in the gas mixtures
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20
Zeolite structures affect the NO bonding strength
Transmission spectra of NO adsorption on Pd/Zeolites
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21
Pd/zeolite show good sulfur tolerance and
can be desulfated at >600C under lean conditions
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22
• Challenges in controlling NOx and HC emissions at low temperatures
• Development of zeolite supported Pd catalysts for low temperature
NO/HC storage and conversion
• Characterization of the active sites in zeolite supported Pd catalysts
• Fully formulated catalysts with zeolite supported Pd catalysts
• System demonstration on vehicles
• Modelling study
Outline
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23
dCSCTM technology utilizes Pd/zeolite providing combined
functions of NOx trap, HC trap, and DOC
NOx Trap
dCSC™
technology
HC Trap DOC
• Store NOx during cold start
• Thermal release of NOx
• Low temperature NOx
conversion activity
• N2 selectivity
• Improved HC storage
capacity
• Additional HC conversion
activity
• Improved CO/HC light-off
activity
• Comparable NO to NO2
activity
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24
DOC @ Pt70:Pd35 = Diesel oxidation catalyst
CSC @ Pt50:Pd90 = New concept cold start catalyst
NOx storage at 80oC
NOx release in the subsequent
temperature ramp
dCSC™ catalysts exhibit high NOx storage capacity/efficiency, NOx thermally release at ~200-350oC
H.-Y. Chen, et al., SAE 2013-01-0535
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25
dCSC™ catalysts also show improved HC/CO conversion,
less N2O formation, and similar NO oxidation activity
NO oxidation NOx storage and N2O formation
HC conversion CO oxidation
H.-Y. Chen, et al., SAE 2013-01-0535
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26
dCSCTM catalysts can be regenerated at ~350C
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
CSC A 1st 2nd 3rd 4th
NO
x S
tora
ge a
t 80C
, 100s
(g N
O2/L
cat)
(750°C/5%H2O/16h aged, SV=30K, NO, CO=200ppm, C10=500 ppm, 10% O2)
Regen
at 650C
Regen
at 350C
Regen
at 350C
Regen
at 350C
Regen
at 350C
H.-Y. Chen, et al., SAE 2013-01-0535
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27
350
650
80
: 10% O2 / 5% H2O / 5% CO2
SO2 = 10 ppm @ 350C for 70 min (0.5 g S/L cat)
S.V. : 30,000 hr-1 (Flow rate = 21.2 L / min)
: 200 ppm NO/200 ppm CO/500 ppm (C1) C10H22/10% O2 / 5% H2O / 5% CO2
Sulfation
: 200 ppm NO/200 ppm CO/1% (C1) C3H6/10% O2 / 5% H2O / 5% CO2
: 10 ppm SO2 /200 ppm NO/200 ppm CO/500 ppm (C1) C10H22 /10% O2 / 5% H2O / 5% CO2
SOx DeSOx
Repeat 4 times
Perframnce test
(100 s store+TPR)
Repeat 10 times
Long-term sulfur tolerance and desulfation properties of the dCSC ™ catalyst were evaluated by SOx/DeSOx cycle test
Desulfation
Perframnce test
(100 s store+TPR)
Perframnce test
(100 s store+TPR)
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28
The dCSC™ catalyst has good sulfur tolerance is stable
after long-term sulfation/desulfation testing
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
0.45
CS
C
1st
S
1stH
6th
S
6th
H
11th
S
11th
H
16th
S
16th
H
21st
S
21stH
26th
S
26th
H
31st
S
31stH
36th
S
36th
H
41st
S
41stH
46th
S
46th
H
51st
S
51stH
Cu
m.
NO
x r
em
oved
(g
NO
2/L
cat)
At 80C, 100 s
Warm-up to 210C
Sulfation was carried at 350oC with an exposure level of 0.5g sulfur /L catalyst
Desulfation was carried at 650oC gas inlet (~720oC catalyst bed) temperature
under lean conditions for 15 minutes
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29
• Challenges in controlling NOx and HC emissions at low temperatures
• Development of zeolite supported Pd catalysts for low temperature
NO/HC storage and conversion
• Characterization of the active sites in zeolite supported Pd catalysts
• Fully formulated catalysts with zeolite supported Pd catalysts
• System demonstration on vehicles
• Modelling study
Outline
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30
dCSC™ catalyst vehicle testing on EU LDD
DO
Cd
CS
C™
cat
SC
RF
®
dCSC™ catalyst SCRF® catalyst
Urea
injectionor
• Eu6 3.0L engine
• DOC
PGM loading: 115g/ft3 4:1(Pt:Pd), total volume: 2.0 L
• dCSCTM
PGM loading: 152g/ft3 8:13(Pt:Pd), total volume: 2.0 L
• Aging
DOC/dCSCTM – hydrothermal 800°C for 16 hours
SCRF® - hydrothermal 800°C for 16 hours
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31
dCSC™ catalyst show excellent NOx storage and
release properties
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32
dCSC™ catalyst engine testing on a 8.9L engine
HDD FTP transient test cycles
dCSC™ SCR-DPF HPSSCR
Urea Dosing
System Fresh/Aged Dimensions
Cold Start
Concept catalyst
Aged at 650°C/100 hrs10.5x6”
SCR-DPF Aged at 650°C/100hrs 10.5x12”
SCR Aged at 650°C/100hrs HP substrate, 600 cpsi, 10.5x6”
M. Naseri, et al., SAE 2015-01-0992
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33
Systems with dCSC™ catalyst + SCRF show promise
for HDD low temperature NOx emission control
33M. Naseri, et al., SAE 2015-01-0992
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34
• Challenges in controlling NOx and HC emissions at low temperatures
• Development of zeolite supported Pd catalysts for low temperature
NO/HC storage and conversion
• Characterization of the active sites in zeolite supported Pd catalysts
• Fully formulated catalysts with zeolite supported Pd catalysts
• System demonstration on vehicles
• Modelling study
Outline
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35
Modeling study has been carried out to compare
various system configurations
� Different system configurations (simulated)
o System 1
o System 2
o System 3
DOC SCR-DPF SCR ASC
PGM2
12”x6”
12”x10”12”x12” 12”x3”
DOC CSFSCR ASC
SCR ASCPGM1
10.5”x4.5”
12”x12”
10.5”x10” 10.5”x3”
Max SV: 150k/hr 75k/hr 90k/hr 300k/hr
� Focus:o NOx reduction
o NH3 slip
o N2O formation (limited systems)
� Design flow:DOC
SCR-DPF/CSF
SCR
ASC
ASCSCRdCSC™Technology
SCR-DPF
PGM2
12”x6”
12”x12” 12”x10” 12”x3”
B. Sukumar, et al., 2014 CLEERS
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36
HD-FTP data used for simulation purpose
0
50
100
150
200
250
300
350
400
0 200 400 600 800 1000 1200
Time (s)
Te
mp
era
ture
(C
)
Average Temp: 219oC
0
200
400
600
800
1000
1200
1400
0 200 400 600 800 1000 1200
Time (s)
NO
x C
on
ce
ntr
ati
on
(p
pm
)
NOx: 8.78 g/kwhr
Engine out data
B. Sukumar, et al., 2014 CLEERS
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37
The system with the dCSC™ technology clearly shows
advantages, mainly due to low temperature NOx reduction
System1:
DOC+CSF+SCR+ASC
System2:
DOC+SCR-DPF +SCR+ASC
System3:
dCSC™ +SCR-DPF +SCR+ASC
HD-FTP
Data
0.91
0.81
0.41
0.40
T+25oC
T+25oC
Very low
NOx levels
0.26
0.34
0.33
Not
modeled
Not
modeled
N2O
(g/kwhr)
NOx
(g/kwhr)
NOx
Conversion
89.6%
90.8%
95.3%
95.4%
>99%
B. Sukumar, et al., 2014 CLEERS
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38
• Low temperature emission control is a major challenge
• Control of cold-start emissions is crucial to meet the future stringent
emission regulations
• Fuel economy and GHG legislation lead to lower exhaust temperatures
• Zeolite supported Pd catalysts exhibit high NOx/HC storage
capacity with high trapping efficiency at low temperatures
• Pd at the exchange sites can adsorb NO directly
• Zeolite structures affect both the NO storage and release profiles
• Catalysts show good tolerance to sulfur poisoning
• Fully formulated catalysts show promising results on vehicle testing
• Modeling study is instrumental in system design
Summary