Post on 07-Feb-2018
OAK RIDGE NATIONAL LABORATORYU.S. DEPARTMENT OF ENERGY
Fuel-Borne Reductants for NOx Aftertreatment: Preliminary EtOH SCR Study
Diesel Engine Emissions Reduction WorkshopAugust 28, 2003
Oak Ridge National Laboratory: John Thomas, Mike Kass, Sam Lewis,John Storey, Ron Graves, Bruce Bunting
Caterpillar: Alexander Panov, Paul Park
Other contributors: Williams-Pekin: Fuel grade ethanolGE Betz: Blending agent, blend testingGromark: Blended fuelIllinois DOCCA: Coordinated delivery
Sponsor: US DOE, OFCVT, Team Leader: Steve Goguen
OAK RIDGE NATIONAL LABORATORYU.S. DEPARTMENT OF ENERGY
Background Leading to Current Effort
1. Previous work: E-diesel, urea SCR, adsorber catalysts. 2. HC SCR receiving less attention than other aftertreatment
technologies.3. ORNL formulated concepts for fuel-borne reductant systems.
EtOH seen as a removable fuel-borne reductant for HC SCR4. Caterpillar marketed an EtOH SCR system for stationary
diesels. Co-operative effort developed between Caterpillar and ORNL
OAK RIDGE NATIONAL LABORATORYU.S. DEPARTMENT OF ENERGY
Comparison of Urea SCR to EtOH SCR
Urea SCR
Commercial technology for stationary engines
NOx Reduction > 90% achievable for 300-500°C
Uses ~ 1:1 NH3/NOx mol ratio
Aqueous solution injected into exhaust
32.5% urea freezes at 12°F
Can produce/slip NH3, N2O, inert PM, reactive solids
EtOH SCR
R&D, utility being explored
NOx Reduction ~ 80% thought to be possible for 400-500°C?
Uses ≥ 3:1 C/NOx mole ratio
Used undiluted, can be fuel-borne
Freezing not an issue
Unwanted products/slip likely:, NH3, N2O, aldehydes, HC
OAK RIDGE NATIONAL LABORATORYU.S. DEPARTMENT OF ENERGY
Initial Project Objectives:
• Evaluate performance of EtOH reductant, Ag-Alumina SCR catalyst system on diesel exhaust. Look at unregulated emissions
• Demonstrate EtOH stripping from E-diesel & its usefulness for NOx reduction.
• Later: consider other fuel-borne reductants, catalysts
OAK RIDGE NATIONAL LABORATORYU.S. DEPARTMENT OF ENERGY
Ethanol Was Stripped From 15% E-Diesel
Using “mild distillation” nearly all EtOH was removed and then recovered
NTRC Analytical Lab.
OAK RIDGE NATIONAL LABORATORYU.S. DEPARTMENT OF ENERGY
Experimental Configuration
• Donated 1999 Cummins ISB, 5.9 L, With Cummins provided cooled EGR, upgraded fuel system, turbo., controls. Configured for “Near-2004” emissions.
• 285 hp DC motoring dynamometer• Measured gases in exhaust via
standard benches• FTIR and GC-MS used to look for
specific HCs, N2O, NH3, Acetaldehyde
FTIR
Analytical Bench: O2NOx, CO, HC, CO2
Analytical Bench: O2NOx, CO, HC, CO2
Injector
Ag Catalyst
Engine
UEGO NGK NOx sensor
PhotoacousticSpectrometer
GC-MSBag SampleMicrodilution
Tunnel
OAK RIDGE NATIONAL LABORATORYU.S. DEPARTMENT OF ENERGY
Cummins 5.9 L Engine
BU
RN
ER
•
OAK RIDGE NATIONAL LABORATORYU.S. DEPARTMENT OF ENERGY
Reductant Injector and Catalyst in the ExhaustORNL/NTRC Cell 3
7 L catalyst located 1 m downstream of the injector.
Automotive EFI injector downstream of turbo outlet.
OAK RIDGE NATIONAL LABORATORYU.S. DEPARTMENT OF ENERGY
SCR Performance Experimental Methodology• Shakedown, de-green catalyst for ~10 hours at 400°C.
• Performance Investigation at Two Engine Conditions / Space Velocities:compared conversion at a low & high space velocity while maintaining similar catalyst temperature and NOx flux.
Test Speed Torque SV Cat T NOxSetting RPM ft-lbs 1/h °C g/min
AVL8-M3 1115 230 21000 360-400 ~1.5~AVL8-M6 2225 180 57000 360-400 ~2.1
Fuel-Reductant Combinations: Fuel Reductant
1. ECD-1 fuel-grade EtOH2. ECD-1 “stripped” fuel-grade EtOH3. E-diesel “stripped” fuel-grade EtOH4. ECD-1 reagent grade EtOH
OAK RIDGE NATIONAL LABORATORYU.S. DEPARTMENT OF ENERGY
Excellent NOx Conversion Was Achieved at 21000/h, 360-400°C
NOx conversion vs C/N ratio, 1115 RPM
0
10
20
30
40
50
60
70
80
90
100
0 1 2 3 4 5 6 7 8 9 10carbon/nitrogen ratio (2X Ethanol/NO2)
NO
x co
nver
sion
(%)
ECD1, fuel EtOH, test 1
Space Velocity ~ 21,000 1/hCatalyst temperature: 360-390 C
OAK RIDGE NATIONAL LABORATORYU.S. DEPARTMENT OF ENERGY
Excellent NOx Conversion Was Achieved at 21000/h, 360-400°C
NOx conversion vs C/N ratio, 1115 RPM
0
10
20
30
40
50
60
70
80
90
100
0 1 2 3 4 5 6 7 8 9 10carbon/nitrogen ratio (2X Ethanol/NO2)
NO
x co
nver
sion
(%)
ECD1, fuel EtOH, test 1
ECD1, fuel EtOH, test 2
ECD1, stripped EtOH, test 3
Space Velocity ~ 21,000 1/hCatalyst temperature: 360-390 C
OAK RIDGE NATIONAL LABORATORYU.S. DEPARTMENT OF ENERGY
NOx Conversion Was Excellent at 21000/h and 360-400°CSelectivity appeared to improved as catalyst is exposed to more sulfur
NOx conversion vs C/N ratio, 1115 RPM
0
10
20
30
40
50
60
70
80
90
100
0 1 2 3 4 5 6 7 8 9 10carbon/nitrogen ratio (2X Ethanol/NO2)
NO
x co
nver
sion
(%)
ECD1, fuel EtOH
ECD1, fuel EtOH
ECD1, stripped EtOH
E-diesel, stripped EtOH
ECD1, fuel EtOH
ECD1, high-grade EtOH
Space Velocity ~ 21,000 1/hCatalyst temperature: 360-390 C
1.5% fuel penalty: energy basis
OAK RIDGE NATIONAL LABORATORYU.S. DEPARTMENT OF ENERGY
Good NOx Conversion Achieved at 57000/h and 360-400°C
NOx conversion vs C/N ratio, 2225 RPM
0
10
20
30
40
50
60
70
80
90
100
0 2 4 6 8 10 12carbon/nitrogen ratio (2X Ethanol/NO2)
NO
x co
nver
sion
(%)
ECD1, fuel EtOH
E-diesel, stripped EtOH
ECD1, fuel EtOH
Space Velocity ~ 57,000 1/hCatalyst temperature: 360-390 C
1.5% fuel penalty: energy basis
NOx conversion very similar for the different fuel-reductant combinations
OAK RIDGE NATIONAL LABORATORYU.S. DEPARTMENT OF ENERGY
HC Slip Changed with Progression of Experiments
Reagent grade EtOH
HC slip vs C/N ratio, 1115 RPM
0
20
40
60
80
100
120
140
160
0 1 2 3 4 5 6 7 8 9 10carbon/nitrogen ratio
HC
slip
(ppm
)
ECD1, fuel EtOH ECD1, fuel EtOH ECD1, stripped EtOHE-diesel, stripped EtOHECD1, fuel EtOHECD1, high grade EtOH
Space Velocity ~ 21,000 1/hCatalyst temperature: 360-390 C
OAK RIDGE NATIONAL LABORATORYU.S. DEPARTMENT OF ENERGY
HC slip at high SV was about the same ppm level, mass flux is ~2.7 times greater
HC slip vs C/N ratio, 21,000 1/h & 57,000 1/h
0
50
100
150
200
250
0 2 4 6 8carbon/nitrogen ratio
HC
slip
(ppm
)
low SV, E-diesel, stripped EtOH
low SV, ECD1, fuel EtOH
low SV, ECD1, reagent EtOH
High SV, E-diesel, stripped EtOH
High SV, ECD1, fuel EtOH
Catalyst temperature: 360-390 C
~ 0.5 g/hp-h
~ 0.19 g/hp-h
OAK RIDGE NATIONAL LABORATORYU.S. DEPARTMENT OF ENERGY
FTIR Results: Ammonia Emissions
0
10
20
30
40
50
60
0 2 4 6 8 10 12C1:NOx Ratio
NH
3 (pp
m)
NH3 @ 21000/hNH3 @ 57000/h
OAK RIDGE NATIONAL LABORATORYU.S. DEPARTMENT OF ENERGY
In the past, some catalyst formed large amounts of N2O
FTIR Results: N2O Emissions
0
1
2
3
4
5
6
0 2 4 6 8 10 12C1:NOx Ratio
N2O
Lev
el (p
pm)
N2O @ 21000/hN2O @ 57000/h
OAK RIDGE NATIONAL LABORATORYU.S. DEPARTMENT OF ENERGY
FTIR Results: NOX, Versus Acetaldehyde Emissions
0
10
20
30
40
50
60
0 2 4 6 8 10 12C1:NOx Ratio
Ace
tald
ehyd
e (p
pm)
Acet @ 21000/hAcet @ 57000/h
OAK RIDGE NATIONAL LABORATORYU.S. DEPARTMENT OF ENERGY
We Have Begun to Look at Other Fuel-borne ReductantsNote: much higher SV and NOx flux
7 liter Ag alumina catalyst, 2225 rpm, 360 deg.C, 90000 SV,
0
10
20
30
40
50
60
70
80
0 1 2 3 4 5 6 7ethanol flow, wt% of fuel flow
% N
OX
con
vers
ion EtOH
Octanol
Heptane
OAK RIDGE NATIONAL LABORATORYU.S. DEPARTMENT OF ENERGY
Reductant stripping experiments
ethanol 78 20 201-propanol 97 20 181-butanol 117 20 17.5n-hexane 69 20 4.9n-heptane 98 20 51-octanol 196 20 0
REDUCTANT BOILING POINT, deg.C
% BLENDED IN ECD1 FUEL
% SEPARATED (rotovap, 100 CC, 10
minutes, 90 deg.C, 200 mm Hg vacuum)
OAK RIDGE NATIONAL LABORATORYU.S. DEPARTMENT OF ENERGY
Low Temperature Effectiveness of Catalyst
Low Temperature Evaluation: For low SV, catalyst temperatures near 250°C, 300°C, 340°C and 370°C were examined at two C/N ratios
NOx conversion vs catalyst temperature
0
10
20
30
40
50
60
70
80
90
100
240 260 280 300 320 340 360 380Ag catalyst temperature (C)
NO
x co
nver
sion
(%)
1115 RPMECD1, fuel ethanolSV varies from 17,000 to 21,000 1/h
C/N ~ 6
C/N ~ 3
OAK RIDGE NATIONAL LABORATORYU.S. DEPARTMENT OF ENERGY
GC-MS Results Clearly Show Different Nature of Slip HC for The 3 EtOH “Grades”
2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.000
200000
400000
600000
800000
1000000
1200000
1400000
1600000
Time-->
Abundance
Reagent grade EtOH
Denatured, fuel grade EtOH: gasoline components seen
E-diesel distilled, fuel grade EtOH: evidence of gasoline & diesel components
SV = 21,000 1/h
C9
C10
OAK RIDGE NATIONAL LABORATORYU.S. DEPARTMENT OF ENERGY
Observations & Conclusions• Ethanol SCR effectively reduced NOx emissions of diesel exhaust for
catalyst temperatures between 360-400°C− moderate C1/NOx ratios− 90% for 21000/h and 80% for 57000/h− Some conversion observed at 250°C
• Saw catalyst performance improve with sulfur exposure• Low levels of N2O (< 6 ppm ) were produced• Ethanol was converted to acetaldehyde: slipped at 57000 1/h• Ammonia was produced (high C/N, low SV), but may not be problematic• Fuel-borne feasibility was demonstrated by stripping EtOH from E-diesel –
use as reductant in the SCR system• Technology may show promise - examining a broader set of
parameters/conditions is warranted