Oct 4, 2011 1
Development of the 2011MY Ford Super Duty Diesel Catalyst System
Christine Lambert, Giovanni Cavataio and Douglas Dobson Ford Research and Advanced Engineering, Dearborn, MI
2011 DEER Conference
Oct 4, 2011 2
Outline
• Background of Ultra-Clean Fuels Program • Tech Selection for 2010 Emissions • Development Challenges with SCR • Diesel MDV Impact on Sustainability • Next Steps • Conclusions & Acknowledgements
Oct 4, 2011 3
DOE Ultra-Clean Fuels Program
Phase I - Initial build/test phase (July 01-July 02) Establish baseline emission control system Deliver engine dynamometer NOx and PM test results Deliver prototype vehicle NOx and PM test results Deliver urea delivery (infrastructure) prototype Phase II - System/component optimization phase (July 02-July 04) Define final system hardware components Deliver NOx and PM performance data from fresh system Phase III - Durability phase (July 04-Dec 05) Definition of durability test procedure Final NOx and PM emission levels Final report for the completed program
Outline of Ford’s program to achieve Tier 2 FTP emission standards for 2007 using ultra low sulfur diesel (ULSD) as a key
enabler for a high efficiency aftertreatment system. Primary Contractor
Subcontractors
Catalyst Suppliers
DEER 2004
Oct 4, 2011 4
Diesel NOx Control Options
Based on the above data, urea SCR was chosen as the prime option for Ford’s UCF Program.
Estimated fuel penalties of
for the LD FTP-75 Typical performance curves for
slightly aged catalysts
SAE 2004-01-1292
Oct 4, 2011 5
Background of UCF Program LDT Exhaust System
urea
DOC
NOx sensor
SCR
DOCDOC
CDPF
Spray Target
to engine intake
• Engine-out NOx lowered by 40% with increased EGR• Low tailpipe NOx achieved with rapid warm-up strategy
• lower thermal mass upstream of catalyst system• engine calibration changes during cold start (post injection & inc. idle speed)
>90% FTP NOx conversion, 0.05 g/mi TP NOx
exhaustflow
Diesel Fuel Properties
• ExxonMobil blended 14,000 gallon batch to represent typical 2007 ULSD
Est. Avg. Proposed Program Proposed‘06 Diesel DOE Program Fuel 2007
Fuel Property Properties Min/Max Delivered Cert. FuelSulfur, ppm 15* 10 / 15 12.5 7 / 15Density, kg/m3 850 820 / 850 841.1 839 / 865Aromatics, vol. % 32 25 / 32 29.5 27 minPolyaromatics, wt. % 10 6 / 11 11.0 no specCetane number 46 44 / 48 44.9 40 / 50T50, C 267 250 / 280 249 243 / 282T90, C 306 300 / 320 307 293 / 332
* As delivered to the vehicle
• Diesel fuel specially blended at <15 ppm-wt Sulfur • 6000 lbs LDDT used as a demonstrator of aged aftertreatment • Catalysts aged on engine dynamometer for 120K mi equivalent • Objective was Tier 2 Bin 5 (120k mi): 0.07 g/mi NOx, 0.01 g/mi PM
DEER 2006
SCR Catalyst Options
Oct 4, 2011 6
0
10
20
30
40
50
60
70
80
90
100
100 150 200 250 300 350 400 450 500 550 600 650
Inlet Gas Temperature (ºC)
Gro
ss N
Ox
conv
ersi
on (%
)
Cu-Based SCR
Fe- Based SCR
Vanadium Based SCR
FTP US06
• Cu/zeolites are best at low temperatures
• Fe/zeolites perform well at high temperatures
• Vanadium based SCRs are not appropriate for US Diesels with Filters
SAE 2007-01-1575
Oct 4, 2011 7
Key Accomplishments of Ford’s UCF Program
• >80% NOx reduction was achieved on a 6000 lbs light-duty diesel truck • Tailpipe NOx was below the T2B8 emission standard (0.2 g/mi NOx) • Proved Cu/zeolite had sufficient durability to withstand filter regens
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
Tailp
ipe
NO
x (g
/mi)
Increase due to loss of postinjection control
4K 4K 50K 120K
4KDOC, 120KSCR
Aging Summary: FTP-75 Weighted NOx
• Loss of DOC activity resulted in higher NOx emissions at 120k mi
Improvement withfresh DOC
34
Durability Test Definition
0
10
20
30
40
50
60
70
80
90
0 250 500 750 1000 1250 1500time (s)
vehi
cle
spee
d (m
ph)
Ford High Speed Cycle (HSC)
• average speed = 47 mph
• max speed = 75 mph
DEER 2006
Bin 5
Oct 4, 2011 8
Key Accomplishments (con’t)
• Urea mixing in the exhaust found to be critical for high NOx conversion
• Developed urea/diesel cofueling dispenser • Predicted long term bottled urea cost of $3.66/gal • Long term cofueled urea price ~$1.50/gal
0
10
20
30
40
50
60
70
80
90
100
150 250 350 450 550 650
Catalyst Temperature (°C)
NO
x C
onve
rsio
n (%
)
HC SCRLNT
Urea SCR
Oct 4, 2011 9
Aftertreatment Selection for 2010 Super Duty
• Ba LNT determined not capable for eng dyno cert • K LNT had durability issues, large size, high cost • Decision was made to certify 90% of diesel MDV fleet volume as complete chassis on
FTP-75 (LEVII F250/F350 - Class 2b 8,501-10,000 lbs and Class 3 10,001-14,000 lbs) • Desire to align chassis and dyno cert NOx control
Urea SCR became the prime option supported by data from Ford’s DOE program
FTP-75 Chassis Cert
HD Dyno Cert
Oct 4, 2011 10
Timeline for 2010 Super Duty Aftertreatment 7/01 Ford’s DOE Contract starts
4Q05 Urea SCR selected for 2010 Diesel
1Q05 Ford’s 2010 Diesel Program starts
3Q07 Diesel Catalyst RFQ to Suppliers
2Q06 Enhanced Cu/zeolite durability achieved
12/05 Ford’s DOE Contract ends
4/10 Super Duty J1
11/10 Super Duty J2
“Advanced” “Research” “Forward Model”
Ford research on SCR ~1990-2001
“not exactly to scale”
Parallel Research on SCR and LNTs
Oct 4, 2011 11
Diesel Aftertreatment Layouts
HC CO2
CO CO2 NO + NH3 N2
PM CO2NH3 N2HC,CO CO2
urea
DOC
NOxsensor
SCR
DOC*DOC*
CDPF
Spray Target
to engine intake
exhaustflow
HC CO2
CO CO2 NO + NH3 N2
PM CO2NH3 N2HC,CO CO2
urea
DOC
NOxsensor
SCR
DOC*DOC*
CDPF
Spray Target
to engine intake
exhaustflow
CDPF
Spray Target
to engine intake
exhaustflow
Spray Target
to engine intake
exhaustflowUCF Program Truck
6000 lbs LDDT • Pt DOC • Cu/beta SCR • Pt CDPF
2011MY Super Duty 8,500 – 14,000 lbs • Pd-rich DOC • Cu/CHA SCR • Pt/Pd CDPF
Cu/beta
Cu/CHA
Pt
Pd-rich
Pt
Pt/Pd
Oct 4, 2011 12
Temperature Operating Windows SCR Inlet Temperature on FTP-75
DOE truck with engine < 6.7L resulted in higher temperatures than production truck.
Temperature Comparison in FTP-75 Cycle
0
50
100
150
200
250
300
350
400
450
0 200 400 600 800 1000 1200 1400 1600 1800
Test Time (s)
Tem
pera
ture
(C)
DOE truck (6000 lbs)
Ford 2011MY Super Duty (9500 lbs)
Vehicle Speed (mph)
Oct 4, 2011 13
Filter Regeneration Strategies
UCF program truck: • Downstream fuel injector • Long regen time studied • 80% regen in <10 min
2010 Super Duty: • Post injection in cylinder • Shorter regen times • Similar temperatures • Refined variables
6.7L Diesel Truck
0
100
200
300
400
500
600
700
800
900
6 7 8 9 10 11 12 13 14 15 16
Time (min.)
Tem
pera
ture
(C) a
nd D
PF L
oad
(mg/
L)
0.8
0.9
1
1.1
1.2
1.3
1.4
1.5
1.6
1.7
DPF
Res
tric
tion
DPF InletDPF OutletDPF LoadDPF Restriction
0
100
200
300
400
500
600
700
800
5 15 25 35 45 55 65Time (min)
Tem
pera
ture
(C)
0
2
4
6
8
10
12
Pres
sure
(kPa
)
DPF InletDPF OutletDelta P - DPF
Oct 4, 2011 14
A Few Challenges Faced During Commercial Urea SCR System Development
• Thermal stability • Ammonia storage • Washcoat adhesion • HC poisoning/coking • Precious metal poisoning • Sulfur effects • Urea specifications and refill
Oct 4, 2011 15
Thermal Stability of DOC
0
0.2
0.4
0.6
0.8
1
100 150 200 250 300
Con
vers
ion
Effi
cien
cy
Temperature (Deg C)
HC Light-Off Conversion2-Mode 100 hrs / 300 ppm S + 20 mgP/gal
20:1
2:11:4
Pt only
0%
10%
20%
30%
40%
50%
150 200 250 300 350 400 450 500 550
% N
O2
of T
otal
NO
x
Temperature (C)
NO2:NOx
Pt only20:1
2:1
1:4
• Addition of Pd to Pt has a stabilizing effect for HC oxidation during cold-start
• Pd also stabilizes Pt for NO oxidation but has no inherent activity itself
Oct 4, 2011 16
Thermal Stability of SCR Catalyst
16
• Thermal stability of Cu/zeolite recently improved from 750 to 900 C (Cu/beta Cu/CHA)
• NO2 no longer needed for low temp conversion • Lower cost aftertreatment now possible
Cavataio 2008-01-1025
• With 20% NO2/NOx feed, the catalyst is durable to 750°C
0
10
20
30
40
50
60
70
80
90
100
150 200 250 300 350 400 450 500 550 600
Temperature (°C)
NO
x C
onve
rsio
n (%
)
4k mi SCR catalyst20h 700°C40h 700°C20h 725°C20h 750°C20h 800°C
SCR Thermal Durability with 20% NO2/NOx FeedgasSCR Catalyst Durability: High Temperature
30K h-1
NO2/NOx = 0.2NH3/NOx = 1
DEER 2005
4NH3 + 4NO + O2 4N2 + 6H2O
Oct 4, 2011 17
Urea Dosing Strategy
0
10
20
30
40
50
60
70
80
90
100
0 100 200 300 400 500 600
Inlet Temperature, °C
% N
Ox
Con
vers
ion
Increasing NH3exposure
• SCR catalysts can store a large amount of ammonia
• A certain amount of ammonia on the catalyst surface is required for a given NOx conversion
• Data at different NH3 load are fed into the urea dosing strategy
DEER 2006
Oct 4, 2011 18
Washcoat Adhesion of DOC and SCR
dieselengine
aqueousurea
DOCPMfilter
dieselengine
aqueousurea
DOC SCRdieselenginedieselengine
aqueousurea
DOCPMfilter
aqueousurea
DOCPMfilter
dieselenginedieselengine
aqueousurea
DOC SCR
Main concerns for pre-filter catalysts: • Loose debris will create backpressure issues in the filter • Precious Metal loss to downstream components (primarily SCR) Result was DOC and SCR Washcoat Loss Targets one order of magnitude lower than for TWC coatings
Oct 4, 2011 19
HC Poisoning/Coking of Zeolitic SCR
0
10
20
30
40
50
60
70
80
90
100
NO
x C
onve
rsio
n (%
)
0
2
4
6
8
10
12
14
16
18
20
Cum
ulat
ive
HC
s (g
/l ca
taly
st)
% NOx Conv.Cum. HC's
DegreenedActivity(250°C,
20% NO2in feed)
Start HCAddition
500°C,10 min
ActivityRegained
End HCAddition
SCR Catalyst Durability: HC
• HC poisoning is reversible after 500°C, lean
HC Inhibition HC Storage/Exotherm
Both issues were resolved by transition from Cu and Fe/beta to Cu/CHA DEER 2004
Oct 4, 2011 20
Sulfur Effects on Cu/zeolite
0
10
20
30
40
50
60
70
80
90
100
150 200 250 300 350 400 450 500 550 600 650
Catalyst Temperature (°C)
NO
x co
nver
sion
(%)
degreened
120k mi sulfated
after regen at 650°C
• Sulfur affects NOx activity below 300C • Sulfur can be removed by lean filter regeneration conditions (>650C) • Amount adsorbed between regens can be tolerated based on 15 ppm-
wt S in diesel fuel
Effect of 20ppm SO2 at 200°C(Calculated miles based on 15ppm fuel sulfur)
0
10
20
30
40
50
60
70
80
90
100
160 180 200 220 240 260 280 300
Temperature(°C)%
NO
x C
onve
rsio
n
0 miles
500miles
Effect of 120K mi at 15ppm fuel sulfur
DEER 2004
Oct 4, 2011 21
Precious Metal Poisoning of SCR
SAE 2008-01-2488 SAE 2009-01-0627
• Pt from upstream DOC can volatilize and interfere with SCR function • Prime indicators are increased NH3 oxidation and N2O make • Front section of catalyst most affected and can be regenerated • Pt DOC may be stabilized with addition of Pd and lower exotherm Ts
EVALUATION of DYNAMOMETER AGED FeSCR CATALYST
Lab flow reactor Pt poisoning of Cu SCR by upstream DOC
-50
-25
0
25
50
75
100
100 150 200 250 300 350 400 450 500 550 600
Inlet Gas Temperature (ºC)
NO
x C
onve
rsio
n (%
)
Non - ContaminatedContaminated
0
10
20
30
40
50
60
70
80
90
100
100 150 200 250 300 350 400 450 500 550 600Catalyst Temperature (ºC)
NO
x C
onve
rsio
n (%
)
1st Inch (Inlet)2nd Inch3rd Inch4th Inch5th Inch6th Inch (Outlet)
Oct 4, 2011 22
Potential Biodiesel Effects
• ASTM D6751-08 limits Group I metals (Na+K) < 5 mg/kg for biodiesel component • The actual deposit amount on the catalysts will depend on the capture efficiency • Real-world biodiesel may have much lower Na & K than the spec
0
1
2
3
4
5
0 20,000 40,000 60,000 80,000 100,000 120,000 140,000 160,000Mileage
Na
or K
Exp
osur
e (w
t%)
SCR
DOC
Potential weight percentage exposure rate of Na/K over a typical DOC and SCR as a
function vehicle mileage. (B100)
-40
-20
0
20
40
60
80
100
100 200 300 400 500 600 700
Inlet Gas Temperature (ºC)
NO
x C
onve
rsio
n (%
)
0.00% K
0.10% K
0.25% K
0.50% K
0.70% K
1.00% K
3.00% K
Cu-SCR#1 NOx activity impact for NO+NH3 as a function of LAB DOPED K contamination level.
SAE 2009-01-2823
Oct 4, 2011 23
Urea Specifications and Refill
• OEMs and suppliers formed USCAR working group to define specifications
• Aqueous urea is sold as “Diesel Exhaust Fluid” or “DEF”
• Current refill uses bottles, drums, totes, and bulk dispensers
• ~ $2.79/gal in bulk • ~ $4.65/gal in bottles http://www.dieselexhaustfluid.com/ Mattina, 16th Annual Fleet Fueling Conference, Sept
2010.
• Websites offer DEF locations
http://www.factsaboutscr.com
Oct 4, 2011 24
Diesel MDV Impact on Sustainability
Year1995 2000 2005 2010 2015
CO
2 (g/
kWh)
at P
eak
Torq
ue
600
700
800
900
1000
Gasoline Diesel
Comparison of Class 2b / Class 3 peak torque brake specific CO2 for medium-duty vehicles 1998 - 2011 calendar years.
• Data from EPA HD database. • Figure from T.J. Wallington, C.K. Lambert, W.C. Ruona, Energy Policy, in review.
• At light/moderate loads the CO2 advantage for SCR-equipped diesel will be > 10%.
Urea SCR used on majority of diesels in 2010+.
0
20
40
60
80
100
120
140
2004 2005 2006 2007 2008 2009 2010 2011 2012
PGM Content Pt Equivalence
Oct 4, 2011 25
Diesel MDV Impact on Sustainability Precious Metal Usage in Super Duty DOCs
Pt rich Pd rich
2011MY J1 DOC+SCR+CDPF
2011MY J2 DOC+SCR+CDPF
DOC only
DOC +CDPF
0.00
500.00
1000.00
1500.00
2000.00
2500.00
Ford LNTResearch 2005
Ford J1 2010 Ford J2 2010
System PGM cost
NOx Catalyst Cost
Total NOx Control Cost*
* including urea hydraulics
Diesel MDV Impact on Sustainability System PGM and NOx Control Cost
Oct 4, 2011 26
DO
C+S
CR
+CD
PF P
GM
DO
C+L
NT+
CD
PF P
GM
LNT
cata
lyst
urea
+
SCR
cat
alys
t
LNT
cata
lyst
SCR
cat
alys
t
DO
C+S
CR
+ C
DPF
PG
M
urea
+
SCR
cat
alys
t
SCR
cat
alys
t
Oct 4, 2011 27
Conclusions • Strategic DOE tech funding can lead to
production components and systems • Important to assess potential early • General focus on saving and/or replacing
critical resources is effective • Tech may be used in products/ways you
did not initially envision
Oct 4, 2011 28
Next Steps for Diesel MDV • Materials cost reductions continue
– PGM reductions – substitution of Pt with Pd
• Aftertreatment efficiency improvements – catalyst durability improvements – catalyst structure improvements – heating strategies – understand non-uniform SCR aging
Oct 4, 2011 29
Further Research Needed on Small Pore Zeolite Catalysts
• Cu/CHA development enabled Cu/zeolite for automotive use • Related patents and publications:
– Zones “Zeolite SSZ-13 and its method of preparation” US4544538, 1985 – Bull et al., “Copper CHA zeolite catalysts”, US7601662, 2009 – Kwak et al., “Excellent activity and selectivity of Cu-SSZ-13 in the selective catalytic
reduction of NOx with NH3”, J. Catal. 275 (2010) 187-190 – McEwen et al., “Integrated operando X-ray and DFT characterization of Cu-SSZ-13
exchange sites during the selective catalytic reduction of NOx with NH3”, Catal. Today, in press.
Basic experimental and computational research
needed to guide rational improvement of small pore zeolites:
• wider temperature window Fe analog? • lower ammonia storage per unit volume • smaller catalyst size per unit volume
Schneider, CLEERS Telecon, Sept 2011
Oct 4, 2011 30
Acknowledgments DOE: DE-FC26-01NT41103 (2001-2005) PNNL-Ford CRADA – Freedom Car (2006-2011) Ford: Kevin Guo, Yisun Cheng, Cliff Montreuil, James Girard, Hungwen
Jen, Scott Williams, Dave Kubinski, Brendan Carberry, Rick Soltis, Devesh Upadhyay, Michiel van Nieuwstadt, Mike Levin and many others
FEV: Erik Koehler, Dean Tomazic, Phillip Adomeit
ExxonMobil: Mike Noorman, Charlie Schleyer, Rich Grosser Catalyst Suppliers: BASF, JMI, Umicore And many, many more …
Oct 4, 2011 31
References • SAE 2002-01-1868, 2004-01-1292, 2007-01-1575, 2008-01-1025, 2009-01-
0627, 2009-01-2823 • Lambert et al., DEER 2004, 2005, 2006 • Cheng et al., DEER 2010 • www.dieselexhaustfluid.com • Mattina, 16th Annual Fleet Fueling Conference, Sept 2010. • www.factsaboutscr.com • Schneider, CLEERS Telecon, Sept 2011 • dieselnet.com