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Advanced Metal-Oxide based SCR CatalystsUmicore AG & Co.KGK. Adelmann, N. Soeger, T. Pauly
IntroductionCurrent stage in the development of SCR catalystsMetal-oxide based SCR catalysts
NO-SCR activity & aging stabilityNH3 storage capacityHC resistanceStart-up behaviour
Summary
Agenda
Introduction
2010 DEER Conference 4
NH3-SCR – Basic Reactions
SCR-Reactions:4 NH3 + 4 NO + O2 4 N2 + 6 H2O Standard SCR
4 NH3 + 2 NO + 2 NO2 4 N2 + 6 H2O Fast SCR
NO
DOCNO2 + NO
Urea
SCR
H2O + N2
NH2 NH2
ONH3 +
HN C O
HN C O CO2NH3 +H2O +
NH3 from Urea:
1) thermal decomposition ofurea to Isocyanic Acid
2) catalytic hydrolysis of Isocyanic Acid to NH3
Current StatusFrom V-based to Zeolite-basedCatalysts
2010 DEER Conference 6
NOx Conversion of State-of-the-art SCR Families
Fe-SCR – 16h/750 CCu-SCR – 16h/750 CV-SCR – 16h/600 C
100 150 200 250 300 350 400 450 500 550T [ C]
0
10
20
30
40
50
60
70
80
90
100
NO
x-co
nver
sion
[%]
Fe-SCR – 16h/750 CCu-SCR – 16h/750 CV-SCR – 16h/600 C
Metal-Oxide based SCR Catalysts
2010 DEER Conference 8
NOx Conversion compared to Fe-zeolite
100 150 200 250 300 350 400 450 500 550T [ C]
0
10
20
30
40
50
60
70
80
90
100
NO
x-co
nver
sion
[%]
Fe-SCR – 16h/750 CMO-SCR – 16h/750 C
100 150 200 250 300 350 400 450 500 550T [ C]
0
10
20
30
40
50
60
70
80
90
100
N2O
con
cent
ratio
n [p
pm]
Fe-SCR – 16h/750 CMO-SCR – 16h/750 C
2010 DEER Conference 9
NOx Conversion compared to Cu-zeolite
100 150 200 250 300 350 400 450 500 550T [ C]
0
10
20
30
40
50
60
70
80
90
100
Cu-SCR – 16h/750 CMO-SCR – 16h/750 C
NO
x-co
nver
sion
[%]
100 150 200 250 300 350 400 450 500 550T [ C]
0
10
20
30
40
50
60
70
80
90
100
N2O
con
cent
ratio
n [p
pm]
Cu-SCR – 16h/750 CMO-SCR – 16h/750 C
2010 DEER Conference 10
Impact of NO/NO2 Ratio
0
20
40
60
80
100
120
0 20 40 60 80
NO2 [%]
NO
x co
nver
sion
[%]
350°C250°C200°C175°C
2010 DEER Conference 11
MO-SCR – Aging Influence
100 150 200 250 300 350 400 450 500 550T [ C]
0
10
20
30
40
50
60
70
80
90
100
MO-SCR – Fresh MO-SCR – 200h/600 CMO-SCR – 48h/650 CMO-SCR – 16 h/750 C
NO
x-co
nver
sion
[%]
2010 DEER Conference 12
200°C
0
20
40
60
80
100
Fe-SCR MO-SCR
NO
con
vers
ion
[%]
fresh200h/600°C48h/650°C16h/750°C
Aging Stability compared to Fe-zeolite
Very high aging stability compared to Fe-zeolite
250°C
0
20
40
60
80
100
Fe-SCR MO-SCR
NO
con
vers
ion
[%]
fresh200h/600°C48h/650°C16h/750°C
2010 DEER Conference 13
NH3 Storage Capacity
Target:
stable NH3 storage
a) over temperature
b) over aging
0
500
1000
1500
2000
2500
150 200 250 300 350 400 450T [°C]
m N
H3 [
mg/
L C
at]
Fe-SCR - fresh
Fe-SCR - 16h/750°C
MO-SCR - fresh
MO-SCR - 16h/750°C
2010 DEER Conference 14
NH3 Storage Capacity
Target:
stable NH3 storage
a) over temperature
b) over aging
0
500
1000
1500
2000
2500
150 200 250 300 350 400 450T [°C]
m N
H3 [
mg/
L C
at]
Fe-SCR - freshFe-SCR - 16h/750°CMO-SCR - freshMO-SCR - 16h/750°CCu-SCR - freshCu-SCR - 16h/750°C
2010 DEER Conference 15
Impact of HC/CO – Exotherm Generation
Risk:
Thermal damage by exotherm generation e.g. over acceleration phase after HC storage
0
100
200
300
400
500
600
700
800
900
600 620 640 660 680 700time (s)
T [°
C]
T in front of catalystFe-SCRCu-SCRMO-SCR
2010 DEER Conference 16
Influence of HC/CO
100 150 200 250 300 350 400 450 500 550T [ C]
0
10
20
30
40
50
60
70
80
90
100
MO-SCR – 16h/750 CMO-SCR – 16h/750 C w/- HC/CO
NO
x-co
nver
sion
[%]
100 150 200 250 300 350 400 450 500 550T [ C]
0
10
20
30
40
50
60
70
80
90
100
NO
x-co
nver
sion
[%]
Fe-SCR – 16h/750 CFe-SCR – 16h/750 C w/- HC/CO
2010 DEER Conference 17
Dynamic Start-up
High dynamic start-up compared to Fe-SCR
Fast NH3 break-through in case of overdosing
MO-SCR - 250°C
0
20
40
60
80
100
0 50 100 150 200time [s]
NO
x-co
nver
sion
[%]
0
100
200
300
400
500
c [p
pm]
NOx-conversion [%] c NH3 [ppm]
Fe-SCR - 250°C
0
20
40
60
80
100
0 50 100 150 200time [s]
NO
x-co
nver
sion
[%]
0
100
200
300
400
500
c [p
pm]
NOx-conversion [%] c NH3 [ppm]
2010 DEER Conference 18
Dynamic Start-up
High dynamic start-up compared to Cu-SCR
Fast NH3 break-through in case of overdosing
MO-SCR - 250°C
0
20
40
60
80
100
0 50 100 150 200time [s]
NO
x-co
nver
sion
[%]
0
100
200
300
400
500
c [p
pm]
NOx-conversion [%] c NH3 [ppm]
Cu-SCR - 250°C
0
20
40
60
80
100
0 50 100 150 200
time [s]
NO
x-co
nver
sion
[%]
0
100
200
300
400
500
c [p
pm]
NOx-conversion [%] c NH3 [ppm]
2010 DEER Conference 19
NOx Conversion vs. Amount of NH3 dosed
0
10
20
30
40
50
60
70
80
90
100
0 0.0005 0.001 0.0015 0.002 0.0025 0.003 0.0035 0.004
Amount of NH3 dosed [mol]
NO
x con
vers
ion
[%]
Cu-SCR Fe-SCR MO-SCR
Summary
2010 DEER Conference 21
Characteristics of Metal-Oxide based SCR Catalysts Improved low temperature performance compared to Fe-
zeolites No significant N2O formation High aging stability Stable NH3 storage over temperature & over aging High tolerance towards hydrocarbon, no risk of exotherm
generation High dynamic start-up behaviour
Thank you!
