Solid State Electrochemical Removal of Pollutants

Solid State Electrochemical Removal of Pollutants
K.K. Hansen
Department of Energy Conversion and Storage
Technical University of Denmark, DTU
e-mail: [email protected]
Outline
•
•
•
•
•
Introduction
Motivation
The idea
History/literature
Work at DTU
– Reduction of NOx
– Oxidation of C3H6
• Conclusion/Outlook
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DTU Energy Conversion, Technical University of Denmark
27-01-14
Sources and main pollutants
• Many sources of flue gas and exhaust gas
• Major pollutants are:
• Particulate matter
• sulphur oxides
• nitrogen oxides
• carbon monoxide
• hydrocarbons
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DTU Energy Conversion, Technical University of Denmark
27-01-14
Motivation
• Why are we pursuing this technology?
– Competitive (no noble metals, low fuel penalty, space requirements,
highly effective)
Kilde: Hamamoto, K. 2009
– Expertice in functional ceramics and processing
– Expertice in electrochemistry
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DTU Energy Conversion, Technical University of Denmark
27-01-14
Electrochemical removal of pollutants
• Current is used to drive the
processes; no extra chemicals!
• Cathode
2NO + 4 e2NO + 2 eO2 + 2 e-
→ N2 + 2 O2→ N2O + O2→ 2 O2-
• Anode:
C + 2 O2CO + O2C3H6 + 9 O22 O2-
→
→
→
→
5
CO2 + 4 eCO2 + 2 e3CO2 + 3H2O + 18 eO2 + 4 e-
DTU Energy Conversion, Technical University of Denmark
27-01-14
Power consumption of an electrochemical reactor
P =U*I
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DTU Energy Conversion, Technical University of Denmark
27-01-14
Literature
• Low current efficiency on noble metals
– Competing reduction of oxygen at cathode
• Addition of adsorption layer increases activity and current efficiency
– RuO2 on silver; 13% current efficiency (Iwayama et al)
– K/Pt/Al2O3 on NiO/Ni; 12% current efficiency (Hamamoto et al)
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DTU Energy Conversion, Technical University of Denmark
27-01-14
Experimental Setup/Conditions
Test set-up
Zoom on the sample position
Tubular reactor scheme
Image of the whole test-set up
Electrochemical, Catalytic Activity and Structural Characterization
Cells: Electrolyte supported or porous cell stacks (self supported)
Temperature range: 300-500 oC
Gas compositions: 1000 ppm NO or 1000 ppm C3H6 + 10% O2
 Catalytic activity; CLD, MS, GC
Electrochemical activity; EIS, CV
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DTU Energy Conversion, Technical University of Denmark
27-01-14
Ni-electrode (1000 ppm NO, 2% O2, -2.5V)
J. Shao, K.K. Hansen, J. Solid State Electrochem., 16 3331 (2012)
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DTU Energy Conversion, Technical University of Denmark
27-01-14
K/Pt/Al2O3|Ag (0.1% NO, 10% O2, 400 oC)
50
16
Conversion
Current effciency
14
40
10
30
8
20
6
Current efficiency / %
Conversion / %
12
4
10
2
0
0.50
0.75
1.00
1.25
1.50
0
1.75
-E / V
J. Shao, K. Kammer Hansen, J. Electrochem. Soc., 160 H294 (2013)
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DTU Energy Conversion, Technical University of Denmark
27-01-14
Power consumption (400 oC)
• P = U*I
– 1.4 l diesel engine, 2500 rpm, 52 kW, 500 ppm NOx
– Power consumption: 2 kW
• Further reduction of power consumption needed.
• Area:
– 16.3 m2, 400 cells, (20*20 cm2), length: 0.2 m
• Further increase of activity needed
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DTU Energy Conversion, Technical University of Denmark
27-01-14
Different cell structures
LSM|CGO
CGO
Electrochemical cell
LSM|CGO
Infiltrated with BaO
nano particles
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Coated with
Ba|Pt|Al2O3
adsorption layer
27-01-14
Ba/Pt/Al2O3|LSM at 450 oC in 0.1% NO, 10% O2
Significantly improved the NOx removal properties above 350 oC
DC
Square wave
J. Shao, K. Kammer Hansen, J. Mater. Chem. A, 1 7137 (2013)
13
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27-01-14
A Porous cell stack
Gas
iii
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27-01-14
SEM of a 5 times Ba-infiltrated cell stack
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27-01-14
The use of a storage compound
NO + O2
Anodic polarization
BaO
LSM15
Ba(NO3)2
LSM15
N2
BaO
O216
LSM15
DTU Energy Conversion, Technical University of Denmark
Cathodic polarization
27-01-14
Non-impregnated LSM15-CGO10 cell stack
Polarisation at 400 oC in 1000 ppm NO +10% O2
NOx concentration
2000
1800
1600
Conc. [ppm]
1400
1200
-3V
-5V
-7V
-9V
1000
800
600
400
200
0
0
17
100
200
300
400
Time [min]
DTU Energy Conversion, Technical University of Denmark
500
600
700
800
27-01-14
BaO impregnated LSM15-CGO10 cell stack
NOx concentration
-5V -7V -9V -7V -5V
-3V
-3V
Conc. [ppm]
2000
Polarisation at 400 oC in 1000 ppm NO +10% O2
1500
1000
500
0
0
200
400
600
Time [min]
800
1000
N2 concentration
700
-9V
600
Conc. [ppm]
Polarisation NOx conversion Current efficiency
[%]
[%]
-3V (a)
0
0
-5V (a)
15
6
-7V (a)
41
9
-9V (a)
61
8
-7V (b)
49
11
-5V (b)
21
9
-3V (b)
2
2
-7V
500
-5V
400
-5V
-3V
300
-3V
200
100
0
0
18
-7V
DTU Energy Conversion, Technical University of Denmark
200
400
600
Time [min]
800
1000
27-01-14
Infiltration of O-2 conductor: CGO10
1000 ppm C3H6 , 10% O2 , O.C.V
0.12
CGO10-Tr
0.11
CGO10-water
2.7 % w/w loading (1 step)
backbone
rC3H6 (mol(s*g))
0.10
•
30 h polarization
0.09
it is possible to observe an increase of
reaction rate after 30 hrs of test;
0.08
•
0.07
0.05
CGO10
infiltration improve the
reaction rate towards propene oxidation
48.7 %
0.06
the
as measured at OCV;
37.2 %
0.04
26.4 %
0.03
350
400
450
Rate enhancement ratio (ρ)
500
Temperature (°C)
1.22
backbone
CGO10-Tr
1.20
T=
CGO10-water
1.18
backbone
CGO10-Tr
CGO10-water
1.26
450ºC
1.23
T= 350ºC
1.16
1.20
1.14
1.17
1.10
1.08
r/r0
r/r0
1.12
1.06
1.14
1.11
1.04
1.08
1.02
1.00
1.05
0.98
200
400
600
800
1000
1.02
applied voltage (mV/cell)
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DTU Energy Conversion, Technical University of Denmark
200
400
600
800
applied voltage (mV/cell)
1000
27-01-14
Activity of electrodes with Co
substitution
3 % Co at the B-site (La0.85Sr0.15)0.99Co0.03Mn0.97O3-δ
Doping with Co on B-site gives much higher electrochemical activity and
reduces the polarisation resistance.
400 oC, 0.1 % NO + 10 % O2 in Ar
300 oC, 0.1% NO + 10% O2 in Ar
0.003
LSM/CGO
LSMCo/CGO
6000
2
cm ]
8000
0.002
0
0
2000
4000
6000
8000
10000 12000 14000 16000 18000 20000
Z' [
cm2]
Temp
Imax(LSCoM)/Imax(LSM)
300 °C
28
400°C
9
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DTU Energy Conversion, Technical University of Denmark
0.001
-2
LSM/CGO
LSCoM/CGO
2000
I [A cm ]
-Z'' [
4000
0.000
-0.001
-0.002
-0.003
-5
-4
-3
-2
-1
0
1
2
3
E [V]
27-01-14
4
5
Mg + Fe infiltration
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DTU Energy Conversion, Technical University of Denmark
27-01-14
Catalytic Activity of La0.65Sr0.35MnO3+
100
NO to N2
NO to NO2
Conversion / %
80
C3H6 to CO2
60
40
20
0
150
200
250
300
350
400
450
500
o
T/ C
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DTU Energy Conversion, Technical University of Denmark
27-01-14
Formation of NO2
100
+propene
3x10
-6
Calculated
75
2x10
-6
50
S
Amount NO2 formed / %
-propene
1x10
-6
25
0
100
200
300
400
500
0
600
o
T/ C
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DTU Energy Conversion, Technical University of Denmark
27-01-14
NO2 reduction
73.8%
27.4%
38.4%
7.4%
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DTU Energy Conversion, Technical University of Denmark
27-01-14
Conclusions
• NOx removal down to 300 oC
• CE at 400 oC: 15 %, with a silver based electrode
• Oxidation of propene shown possible
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DTU Energy Conversion, Technical University of Denmark
27-01-14
The group
Kent Kammer Hansen
Frederik Berg Nygaard
Kjeld Bøhm Andersen Rebecka Werchmeister
Marie Lund Traulsen
26
Anja Zarah Friedberg
Janet Bentzen
Jing Shao
Davide Ippolito
DTU Energy Conversion, Technical University of Denmark
Cristine Grings Schmidt
27-01-14

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