diesel fuel quality and sulfur effects on catalyst-based exhaust emission controls: manufacturers of...
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Diesel Fuel Quality and Sulfur Effects on Catalyst-Based Exhaust Emission
Controls:
Manufacturers of Emission Controls Association
May 2000
Presentation OutlinePresentation Outline
Introduction Impact of Fuel Sulfur on Catalyst Emission Control
Technology Noble Metal Function NOx Control Technology PM Control Technology
Conclusions
IntroductionIntroduction
Fuel Quality Is an Integral Part of a Complete Emission Control System for Both Gasoline and Diesel Powered Vehicles
Although Other Fuel Constituents Affect Engine-Out Emissions, Fuel Sulfur Is the Single Most Important Constituent for Catalyst-Based Emission Control Technology
Sulfur in Diesel Fuel Adversely Affects the Emission Control Performance of All Catalyst-Based Emission Control Technologies
Introduction (cont.)Introduction (cont.)
Near Zero Diesel Sulfur Levels Would Enable the Application of the Full Range of Control Technologies and Would Permit Each Technology to Be Optimized for Maximum Emission Control Performance
EPA Has Proposed Phase 2 On-Road HDE Standards of 0.2 g/bhp-hr NOx and 0.01 g/bhp-hr Particulate to Take Effect in the 2007 Timeframe
Fuel Sulfur Levels Will Be Instrumental in Meeting These Aggressive Targets
Zeolite or refractory oxide support
Precious Metal
SOSO33
SOSO44==
Transition Metal
HH22SOSO44
OO22
Sulfate make
Sulfur inhibition
Sulfate Poisoning
SOSO22
Sulfur EffectsSulfur Effects
Test procedure: Engine test bench, partial load, 1.9 L TDI engine
Noble Metal Function: Sulfur Increases Noble Metal Function: Sulfur Increases Light-Off Temperature and Reduces Peak Light-Off Temperature and Reduces Peak
ConversionConversion
80 120 160 200 240
100
80
60
40
20
0
CO
Co
nve
rsio
n (
%)
Exhaust temperature before catalytic converter (oC)
Regular Diesel fuel (350 ppm S)
Quissel et al, VDA-Fortschrittsberichte, 12 (348), Bd. 2, 225-246 (1998)
80 120 160 200 240
100
80
60
40
20
0
CO
Co
nve
rsio
n (
%)
Exhaust temperature before catalytic converter (oC)
Sweden Diesel fuel (<10 ppm S)
1/2 hr Conditioned32 hr Aging
OxidationCatalyst
Sulfur Adversely Affects Non-Precious Sulfur Adversely Affects Non-Precious Metal Metal
Lean NOx CatalystsLean NOx Catalysts
0
5
10
15
20
25
30
35
40
45
50
250 350 450 550 650
Inlet Temperature (C)
NO
x C
on
vers
ion
(%
)
NOx = 500ppmHC/NOx = 5SV =25,000/hr
1 ppm
350 ppm
NOx Adsorbers: Sulfur EffectsNOx Adsorbers: Sulfur Effects
Sulfur Poisoning and Inhibition Inhibits Conversion of Unregulated Emissions (e.g. toxic HC
emissions) Prevents NOx Conversion Increases Fuel Economy Penalty
Sulfate Make
Sulfur Poisons NOx Adsorbers Sulfur Poisons NOx Adsorbers Storage SitesStorage Sites
30s/2s30hrs at 400 C
0
10
20
30
40
50
60
70
80
90
100
200 250 300 350 400 450 500
Evaluation Temperature (C)
NO
x C
onve
rsio
n (
%)
13
0
20
40
60
80
100
120
1 2 3 4 5 6 7 8 9 10 11 12
Depth into Washcoat
S/B
a M
ola
r R
atio
(%
)
200 ppm 100 ppm 0 ppm40 ppm*equivalent fuel sulfur content*
The extent of poisoning increases with fuel sulfur content and duration of exposure.
Low Levels of Sulfur Are Needed to Maintain NOx Adsorber Catalyst Efficiency
0
20
40
60
80
100
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
Miles Traveled
Cat
alys
t N
Ox
Bre
akth
rou
gh
, %
7 ppm Sulfur FuelCatalyst "A"
150 ppm Sulfur FuelCatalyst "A"
300 ppm Sulfur FuelCatalyst "B"
0.1 ppm Sulfur FuelCatalyst "c"
7 ppm Fuel:1700 Miles
150 ppm Fuel:115 Miles
300 ppm Fuel:55 Miles
Mileage Interval vs Fuel Sulfur Content which Leads to a 5% Decrease in
Catalyst Efficiency(Note: T/P NOx emissions double when catalyst
efficiency drops from 95 to 90% )
0.1 ppm Fuel:>5,000 Miles
0 20 40 60 80 100 120 140 160
100
90
80
70
60
50
40
30
20
10
0
Poisoning period (hr)
NO
x C
on
vers
ion
(%
)
Gasoline fuel: California Phase 2 (ca. 30 ppm S) - Catalytic converter B
Gasoline fuel: Super Plus (130 ppm S)Catalytic converter A
Gasoline fuel: California Phase 2 (ca. 30 ppm S)Catalytic converter A
Cycle during poisoning and measurement: 30/2 S lean/rich
Test Procedure: Engine test bench, partial load operation
Quissel et al, VDA-Fortschrittsberichte, 12 (348), Bd. 2, 225-246 (1998)
Advances in NOx Adsorber Sulfur Advances in NOx Adsorber Sulfur ResistanceResistance
Catalytic Particulate Filters: Sulfur Catalytic Particulate Filters: Sulfur EffectsEffects
Sulfur Poisoning and Inhibition Inhibits Control of Unregulated Emissions Increases Regeneration Temperature
Formation of Sulfate
Catalytic Filter Regeneration Is Adversely Affected by Sulfur
A Low Regeneration Temperature Insures Reliable Catalytic Filter Operation and Durability
A Low Regeneration Temperature Allows Filter Technology to Be Applied to a Broad Range of Vehicle Applications
Higher Sulfur Levels in Diesel Fuel Increase a Catalytic Filter’s Regeneration Temperature In the DECSE Program, Increasing the Fuel Sulfur Content
from 3 ppm to 30 ppm Increased the Regeneration Temperature of Two Different Catalytic Filter Systems by 23 to Over 30 oC.
Experience in Countries Characterized by Very Cold Temperatures, e.g. Sweden, Indicates that There Have Been No Durability Problems with Systems Having Accumulated in Excess of 475,000 km when Diesel Fuel with <10 ppm Is Used
IMPACT OF FUEL SULFUR ON HEAVY DUTY PM EMISSIONSASSUME: BSFC = 0.355 H2O/SO4 = 1.3
0.000
0.005
0.010
0.015
0.020
0.025
0.030
0 5 10 15 20 25 30 35 40 45 50
FUEL SULFUR, ppm
SU
LF
UR
CO
NT
RIB
UT
ION
TO
PM
g
/bh
p-h
r
40% S CONV 50% S CONV 60% S CONV DECSE SwRI
Impact of Sulfur on Heavy-Duty PM Impact of Sulfur on Heavy-Duty PM EmissionsEmissions
90% Reduction from 2004 Std.
CALCULATED IMPACT OF FUEL SULFUR ON LIGHT DUTY DIESEL PM EMISSIONS ASSUME: 25 MPG H20/SO4=1.3
0.000
0.005
0.010
0.015
0.020
0.025
0.030
0.035
0.040
0.045
0.050
0 5 10 15 20 25 30 35 40 45 50
FUEL SULFUR, PPM
SU
LFA
TE
CO
NT
RIB
UT
ION
TO
PM
, G
/MIL
E
25% S CONV
50% S CONV
75% S CONV
TIER II LIMITS BINS 6-7
TIER II LIMITS BINS 2-5
Impact of Sulfur on Light-Duty PM EmissionsImpact of Sulfur on Light-Duty PM Emissions
The DECSE Study Is Showing That Low Sulfur Is Critical to Achieving a 0.01 g/bhp-
hr PM Standard(System 1)
From DOE website; Diesel Emission Control - Sulfur Effects;
Sponsored by DOE, EMA, MECA, and National Labs
OICA 13-mode cycle; CAT 3126 engine
~95% efficiency at 3 ppm sulfur
~70% efficiency at 30 ppm sulfur
~0% efficiency at 150 ppm sulfur
Negative efficiency at 350 ppm sulfur
00.020.040.060.080.1
0.120.140.160.180.2
3 30 150 350
OtherSulfateSolid
The DECSE Study Is Showing That Low Sulfur Is Critical to Achieving a 0.01 g/bhp-
hr PM Standard(System 2)
From DOE website; Diesel Emission Control - Sulfur Effects;
Sponsored by DOE, EMA, MECA, and National Labs
OICA 13-mode cycle; CAT 3126 engine
~95% efficiency at 3 ppm sulfur
~70% efficiency at 30 ppm sulfur
~0% efficiency at 150 ppm sulfur
Negative efficiency at 350 ppm sulfur
0
0.05
0.1
0.15
0.2
0.25
3 30 150 350
OtherSulfateSolid
Status of Reducing Impacts of Sulfur Status of Reducing Impacts of Sulfur on NOx Adsorberson NOx Adsorbers
MECA Members Continue Research Efforts in Decreasing Sulfur Sensitivity
BUT, Desulfurization Frequency Needs to Be Minimized for
Commercial Viability of NOx Adsorbers Minimize Fuel Economy Penalty Maximizes the Opportunity for Operating Conditions
Conducive to Desulfurization to Be Met Under Normal In-Service Operation
To Meet Very Low Emission Levels Only an Approximately 5% Decrease in Performance Can Be Tolerated
Control of Unregulated Emissions Is Inhibited Off-Cycle Emissions During Desulfurization Inhibition of the Performance of Other Emission Control
Devices Sulfur Inhibition Is Cumulative
Status of Reducing Impacts of Sulfur Status of Reducing Impacts of Sulfur on Catalytic Particulate Filterson Catalytic Particulate Filters
MECA Members Continue Research Efforts in Decreasing Sulfur Sensitivity
BUT, Sulfur Significantly Increase the Balance Point
Temperature Due to Sulfur Inhibition which Adversely Affects Filter Regeneration
Control of Unregulated Emissions Is Inhibited Cold Climatic Conditions Exasperate the Effects of
Sulfur Inhibition Sulfur Inhibition Is Cumulative
ConclusionConclusion
To Help Insure that Diesel Fuel Remains Competitive with Other Fuels, It Is Incumbent on the Engine Manufacturers, the Emission Controls Industry, and the Fuel Providers to Work Together to Provide a “Truly Clean” Diesel Engine so that the Public Accepts the Fuel As an Environmentally Friendly, Safe, and Efficient Means to Meet the Nation’s Transportation Needs