in gasoline exhaust gas - nanoparticlespassive regeneration (t=200…450°c) 2 no + o 2 2 no ......
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TU Bergakademie Freiberg · Institute of Energy Process Engineering and Chemical Engineering · Chair of Reaction Engineering
Reiche Zeche · Fuchsmuehlenweg 9 · 09599 Freiberg · Phone: +49 3731 394551 · Fax: +49 3731 394555 · www.iec.tu-freiberg.de
Soot oxidation on manganese oxide catalysts
in gasoline exhaust gas
O 2r
r 2 (g)O
2
1
2
2
4
3COOCO(g)
r
r 2
6
5
2 CO(g)COr
r
2
O1
11 θcRT
EexpAr
2
2
Oo22
22 θRT
αEexpAr
θOCO
333 θc
RT
EexpAr
2COO44
44 θRT
EexpAr
θc
RT
EexpAr
2CO5
55
O 2
r
r 2 (g)O
2
1
2
4
3OCO(g)
r
r
dTcH
2
1dTcHdTcHΔH
T
T
Op,
0
Of,
T
T
COp,
0
COf,
T
T
COp,
0
COf,0
22
00
22
T
dTcS
2
1
T
dTcS
T
dTcS
1ΔS
T
T
Op,
0
O
T
T
COp,
0
CO
T
T
COp,
0
CO0
22
00
22R
4OFe3OFe2OFe1OFeO
OFeOFe rArAr2Ar2AdT
dΘβΓA
323232323232
3OFe4OFe6OFe5OFe
CO
OFeOFe rArArArAdT
dΘβΓA
32323232
2
3232
6OFe5OFeein(g),,COaus(g),,CO rArAcVcV323222
2OFe1OFeein(g),,Oaus(g),,O rArAcVcV
323222
3OFeein(g),,COaus(g),CO, rAcVcV32
Christian Singer, Maria Nitzer-Noski, Sven Kureti
Development of particulate emission limits
of EU for gasoline cars
2
0
1
2
3
4
5
6 mg/km
EU VI
PN 6E12 #/km
Strategies of particulate filter regeneration
Passive regeneration (T=200…450°C)
2 NO + O2 2 NO2
2 NO2 + “C” CO2 + 2 NO
Fuel Borne Catalyst: metal-organic compounds
“C” + O2 CO2 T > 300°C
Active regeneration (fuel post-injection)
“C” + O2 CO2 T > 600°C
Catalytic GPF (CGPF): CeO2 and Fe2O3 based catalysts
“C” + O2 CO2 T > 500°C
3
Evaluation of MnOx catalysts
DOC DPF
K. Ohno, Ph.D. thesis 2005
Temperature Programmed Oxidation (TPO)
Plug flow reactor with packed bed
4
T
t
DT/Dt=200 K/h
25°C
Evaluation of soot oxidation activity
PC
TI
FIC
Ar
H2
NO
O2
CO
TI TI
FIC
FIC
FIC
FIC
T controller
MFC
FIC
H2O
FICHC
N2
ppm
NOxppm
O2
vol.%
HCppm
COx
ppm
catalystTPO conditions
Laboratory test bench
y(O2)=1%, y(H2O)=2%, y(N2)=97%
F=500 ml/min (STP)
tight contact, loose contact
m=0.9 g (ncat/nsoot=2)
Model soot Printex U
Screening of MnOx catalysts
Physical-chemical characterisation
• XRD
• N2-physisorption (BET, BJH)
• SEM
• NH3-TPD
300
350
400
450
0 25 50 75 100
Tm
ax
/ C
n(NH3) / µmol/g
Structure-activity correlation
5
FSP-MnOx best catalyst
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
200 300 400 500 600 700 800
y(C
O2)
/ v
ol.
%
T / C
Mn3O4 wet
Mn3O4 FSP
Mn2O3 A.A.
Mn2O3 J.M.
Mn2O3 nano
Effect of contact: tight vs. loose
6
FSP-Mn2O3 requires contact to soot particles
0.0
0.2
0.4
0.6
0.8
1.0
0.0
0.2
0.4
0.6
0.8
1.0
200 300 400 500 600 700 800
y(C
Ox)
/ v
ol.
%
y(C
O2)
/ v
ol.
%
T / C
tight contactloose contactbare soot
Tight and loose contact mode
7
Loose contact Tight contact
Effect of O2 on activity of FSP-Mn2O3
8
0
0.2
0.4
0.6
0.8
1
200 300 400 500 600 700 800
y(C
O2)
/ v
ol.
%
T / C
1.0 vol.% O20.8 vol.% O20.5 vol.% O20.4 vol.% O20.3 vol.% O20.2 vol.% O20.1 vol.% O2
0
100
200
300
400
500
600
700
0
0.1
0.2
0.3
0.4
0.5
0.6
300 500 700 900T
/
C
y(C
O2)
/ v
ol.
%
t /s
9
1.0% O2: ΔTmax=25 K
2.5% O2: ΔTmax=70 K
Temperature inside catalyst bed
1.0%O2
Temperature evolution in catalyst bed
Temperature on catalyst surface
2.5%O2
1.0%O2
0
100
200
300
400
500
600
700
0
0.2
0.4
0.6
0.8
1
1.2
1.4
400 540 680 820
T /
C
y(C
O2)
/ vo
l.%
t /s
2.5%O2
10
transfer of ca. 17% of catalyst oxygen
importance of bulk oxygen
TPO
HTPR
Isotopic TPO with 18O2
MnOx
Thermal stability of FSP-Mn2O3
11
0.0
0.2
0.4
0.6
0.8
1.0
200 300 400 500 600 700
y(C
O2)
/ v
ol.
%
T / C
fresh
after 1050°C (4 h)
Activity after exposure for 4 h at 1050°C (static air)
SO2 stability of FSP-Mn2O3
12
Activity after SO2 exposure for 16 h at 250°C
(20 ppm SO2, 5% O2, 8% H2O, N2 balance)
0.0
0.2
0.4
0.6
0.8
1.0
200 300 400 500 600 700
y(C
O2)
/ v
ol.
%
T / C
fresh
after SOxexposure
Oxidation of ethanol-based soot on FSP-Mn2O3
13
very similar oxidation kinetics
of different soot samples
0
0,25
0,5
0,75
1
0 200 400 600 800
y(C
O2)
/ v
ol.
%
T / C
E0 FSP 550
E65 FSP 550
E100 FSP 550
Soot obtained from combustion of iso-octane/ethanol (Prof. Trimis, KIT)
Soot characteristics and catalytic oxidation
Soot d / nm S(BET) / m2/g
PrintexU 25 91
E0 12 425
E65 10 211
E100 6 96
14
Test of catalytic particulate filters
300 cpsi
60% porosity
FSP bench
Lab-GPF
Catalytic coating of lab-GPF Soot deposition on catalytic GPF
TPO conditions
Catalyst loading: 22 g/L
Soot loading: ca. 1.5 g/L
y(O2)=1%, y(H2O)=2%, N2 balance
F=6500 mL/min (S.V.≈20’000/h)
fuel air
N2
GPF
soot generator
1“
2“
1“
15
0
50
100
150
200
250
300
350
100 200 300 400 500 600 700
y(C
O2) / p
pm
T / °C
mit Kat
ohne Kat Effect of catalytic coating
Presence of loose and tight contact mode
Implementation into Three Way Catalysts
0
20
40
60
80
100
150 200 250 300 350 400 450 500 550 600
X / %
T / C
C3H6
ESF5-K1
ESF4g
ESF5-K2
ESF4o
0
20
40
60
80
100
150 200 250 300 350 400 450 500 550 600
X / %
T / C
CO
ESF5-K1
ESF4g
ESF5-K2
ESF4o
0
20
40
60
80
100
150 200 250 300 350 400 450 500 550 600
X / %
T / C
NO
ESF5-K1
ESF4g
ESF5-K2
ESF4o
C3H6 CO NO
catalytic GPF
Activity of GPF coated with FSP catalyst
bare GPF
Summary
16
Manganese oxides are effective in soot oxidation and show high resistance
towards thermal and SOx exposure
Manganese oxide catalyst requires
intimate contact to soot
FSP-Mn2O3 strongly supplies bulk oxygen
to soot
Beneficial effect of FSP catalyst also
occurs onto particulate filters
MnOx
Financial support from German Agency of
Renewable Resources (project BiOtto) is
thankfully acknowledged
Preparation and characterisation of the soot
17
number of primary particles
0 20 40 60 80 100d / nm
fuel air
N2
C3H6/O2 diffusion flame
Adsorbed species: 2.5 wt.%
Chemical composition
98.8 wt.% C
0.7 wt.% O
0.5 wt.% H
<0.1 wt.% N
SBET = 65 m2/g
d = 45 nm (most frequent diameter)
200 nm
Thermal stability of FSP-Mn3O4 catalyst
18
0
4
8
12
16
250 300 350 400 450
y(C
O2)
/ vo
l.%
T / C
fresh
after 4 h at 1050 C (air)
after 16 h at 750 C (10% H2O, 10% O2)
TPO conditions:
y(O2)=10%, N2
DT/Dt=100 K/h
m=0.9 g
ncat/nsoot=2
Performance of lab-DPF coated with FSP-Mn3O4
under diesel conditions
19
0
50
100
150
200
250
300
350
150 250 350 450 550 650 750
y(C
Ox)
/ vo
l.%
T / C
bare DPF
FSP-Mn3O4
@DPF
0
50
100
150
200
250
300
350
150 250 350 450 550 650 750
y(C
Ox)
/ vo
l.%
T / C
bare DPF
Ce@DPFFSP-Mn3O4
@DPF
TPO conditions:
Soot load: ca. 1.5 g/L
Catalyst load: 22 g/L
y(O2)=10%, y(H2O)=2%, N2
DT/Dt=100 K/h
S.V.≈20’000/h
20
0
50
100
150
200
250
300
350
100 200 300 400 500 600 700 800
y(C
Ox)
/ vo
l.%
T / C
diesel conditions
gasoline conditions
TPO conditions:
Soot load: ca. 1.5 g/L
Catalyst load: 22 g/L
y(O2)=1 or 10%, y(H2O)=2%, N2
DT/Dt=100 K/h
S.V.≈20’000/h
Performance of lab-DPF coated with FSP-Mn3O4
under diesel and lean gasoline conditions
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