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Available online at www.sciencedirect.com
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Direct internal reforming molten carbonate fuel cell with
coreeshell catalyst
Pengjie Wang a,b, Li Zhou a,*, Guanglong Li a,c, Huaxin Lin a, Zhigang Shao a,**,
Xiongfu Zhang c, Baolian Yi a
a
Fuel Cell System and Engineering Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian,
Liaoning 116023, China
b
Graduate University of Chinese Academy of Sciences, Beijing 100049, China
c
School of Chemistry, Dalian University of Technology, Dalian, Liaoning 116012, China
article info
abstract
Article history:
A sort of coreeshell catalyst as a novel anti-alkali-poisoning concept was prepared, tested
Received 25 June 2011
and applied in the direct internal reforming molten carbonate fuel cell (DIR-MCFC). Results
Received in revised form
showed that the coreeshell catalyst possessed good alkali-poisoning resistance capacity,
21 September 2011
which was explained well by the micropore model of the catalyst. And the cell perfor-
Accepted 28 September 2011
mance could keep above 0.75V during 100 h test. When the steam carbon ratio was 2
Available online 23 November 2011
(S/C ¼ 2) and the current density was 150 mA cm2, the cell potential varied from 0.826 to
0.751 V and the voltage fluctuant phenomenon was explained specifically. Furthermore,
Keywords:
the short stack (three cells) was also assembled, and the maximum output power density
Molten carbon fuel cell
of the short stack was 338.4 mW cm2. The above results indicated that the coreeshell
Direct internal reforming
catalyst could be applied into the DIR-MCFC successfully.
Coreeshell catalyst
Copyright ª 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights
reserved.
1.
Introduction
Molten carbonate fuel cell (MCFC) is a kind of high temperature fuel cell with the operating temperature at 650 C. MCFC
uses hydrogen as fuel, which can be obtained from the
reforming gas of CH4 [1], C6H5OH [2] or landfill gas [3] etc.
Recently, the reforming of steam and methane (SRM) are often
combined with MCFC. There are three ways for the combination of MCFC and SRM technology: external reforming (ER),
indirect internal reforming (IIR) and direct internal reforming
(DIR). For DIR technology, the reforming catalyst is put in the
anode chamber and the reforming reaction of steam and
methane occurs in the anode chamber. As a result, the
hydrogen and carbon monoxide from SRM reaction are
consumed directly by the electrochemical reaction. In addition, the heat produced from the electrochemical reaction is
consumed by SRM reaction simultaneously. Therefore, the
DIR-MCFC has an intrinsically high reforming efficiency.
SRM is a widely practiced technology to produce hydrogen
or synthesis gas [4] Intensive research efforts has been carried
out on Ni-supported catalysts for steam reforming [4e7]. Roh
et al. [4,5] have compared the catalytic activity of various Nibased catalysts, including Ni/Ce-ZrO2, Ni/ZrO2, Ni/MgAl2O4
and Ni/CeO2. Among of them, Ni/Ce-ZrO2 showed higher
methane conversion w60% for CH4:H2O ¼ 1:3 at
750 CLaosiripojana et al. [6] compared the reactivity of
methane stream reforming over Ni/Ce-ZrO2, Ni/CeO2 and
Ni/Al2O3. At the condition of CH4:H2O:H2 ¼ 1:3:0.2 and 900 C,
* Corresponding author. Tel.: þ86 411 84379123; fax: þ86 411 84379185.
** Corresponding author. Tel.: þ86 411 84379153; fax: þ86 411 84379185.
E-mail addresses: [email protected], [email protected] (L. Zhou), [email protected] (Z. Shao).
0360-3199/$ e see front matter Copyright ª 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
doi:10.1016/j.ijhydene.2011.09.151
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Ni/Al2O3 showed the highest initial methane conversion of
72%. Although Ni/Ce-ZrO2 presented better resistance toward
carbon formation and more stable catalytic activity than Ni/
Al2O3, the former proved difficult to commercialize owing to
the high cost [7]. So Ni/Al2O3 was commonly used due to low
cost and easily available.
However, the reforming catalyst of DIR-MCFC is more
prone to be poisoned by alkali metal electrolytes [8] in DIRMCFC. Attentions of the scholars on MCFC have been attracted to study the mechanism of the alkali-poisoning of the
catalyst. Covering and sintering of Ni active sites, formation of
Ni-containing solid solution, and blocking of pore structure
are suggested as major deactivation processes [9,10]. Therefore, the alkali-resistance catalysts are developed for application on DIR-MCFC. Park et al. [11] prepared Ni/MgAl2O4 by
co-precipitation method, which showed good alkaliresistance performance. However, they didn’t evaluate the
catalyst in cell. Li et al. [12] not only prepared the Ni/MgSiO3
catalyst, but also evaluated the catalyst in cell. This kind of
catalyst showed alkali-resistance performance, and the cell
with this catalyst operated very well.
Our co-worker Zhou et al. [13] prepared the coreeshell
nickel catalysts by encapsulating Ni/SiO2 and Ni/Al2O3 within
zeolite shells. These catalysts showed better (Li/K)2CO3resistance in the out-of-cell test for 60h.
In this study, the coreeshell Ni-based catalyst (Sil-1/Ni/
Al2O3) was prepared. Specifically, the core Ni/Al2O3 was
prepared by us, which were encapsulated within zeolite shells
by our co-worker. The coreeshell Ni-based catalyst was
applied into the unit cell and short stack (three cells) of DIRMCFC. The cell performance was evaluated, including the
initial cell performance and the durability of the cell for 100h
operation.
2.
Experimental
2.1.
Preparation of coreeshell Ni-based catalyst (Sil-1/
Ni/Al2O3)
Certain proportion of Ni(NO3)2$6H2O(AR, Shantou Xilong
Chemical Ltd.), were dissolved in deionized water, then the gAl2O3 beads (10e20 mess, Dalian Haixin Chemical Ltd) was
immersed in the solution, and the catalyst loading the certain
proportion of Ni was dried at 373 K for 12 h, followed by air
calcinations in the furnace at 923 K for 4 h.
These prepared catalysts were coated with zeolite shell
with our co-workers’ help according to the procedure reported
[13]. The catalysts were examined by scanning electron
microscopy (SEM, KYKY-2000B). After 100h test, the coreeshell
catalyst was also analyzed by energy-dispersive X-ray spectroscopy (EDX, JSM6360-LV). Moreover, the exit gas were
analyzed during the test of the coreeshell catalysts by Gas
Chromatography (GC-7890T).
2.2.
Preparation of aeLiAlO2 power and matrices
Coarse aeLiAlO2 powder was prepared by the calcinations of
Li2CO3 (A.P., Xinhua Chemical Reagent Factory, Beijing, China)
with aeAl2O3 (A.P. Chengdu Chemical Reagent Factory, Si
Chuan Province, China) in an equal molecular ratio at 973 K.
Before the calcinations, Li2CO3 and aeAl2O3 were mixed
sufficiently by ball-mill. Fine aeAl2O3 powder was prepared by
“Chloride” synthesis method [14]. The aeLiAlO2 powder was
mixed with deionized water solvent, polyvinyl alcohol (PVA)
binder and other additives to form a homogeneous slurry.
Then the matrices were fabricated by tape casting [15].
2.3.
Assemblage and assessment of DIR-MCFC
The physical parameters of matrix and electrode were listed
in Table 1.
The unit cell and short stack (three cells) were assembled.
For each unit cell, 4 g catalyst was pre-stored in the anode
chamber and 7.5g electrolyte (0.62Li2CO3þ0.38K2CO3, mol%)
was put in the cathode chamber before the components were
assembled into the cell.
In order to ensure all the components contacts well, the
assembling pressure of the unit cell and the short stacks were
kept at 2.361t and 4.473t, respectively. When the temperature
reached 650 C, gas tightness was examined by N2. The
mixture gas of O2þCO2 (O2/CO2 ¼ 40/60) as oxidant and that of
H2þCO2 (H2/CO2 ¼ 80/20) as fuel gas were fed to the fuel cell
and flowed though the cathode and anode chambers,
respectively. After the coreeshell catalyst in the anode was
reduced for 8 h, the fuel gas was replaced with CH4þH2O, and
the performance of the unit cell and short stack were tested
with SUN-FEL10A electronic load (Dalian sunrise power
limited-liability company).
3.
Results and discussion
3.1.
Out-of-cell test
The coreeshell Ni-based catalyst (Sil-1/Ni/Al2O3) was evaluated in the simulated electrolyte surrounding as in the cell by
our co-worker and the results were presented in Fig. 1. As
shown, the fresh Ni/Al2O3 catalyst exhibited high methane
conversion of around 80%, but after 5h alkali vapor treatment
in the apparatus (see Fig. 2), the methane conversion
decreased to less than 1%. In the contrast, the alkali vapor
treatment coreeshell catalyst (poisoned Sil-1/Ni/Al2O3) kept
a stable methane conversion of around 62%, which presented
the shell played an important role in protecting the core from
alkali-poisoning. The principle of alkali-resistance and the
shell structure of the Sil-1/Ni/Al2O3 catalyst were shown in
Fig. 3, and SEM images of Sil-1 seeds layer of the catalyst was
shown in Fig. 4. As shown in Fig. 3, the pore diameter of the
Table 1 e The physical parameters of matrix and
electrode in DIR-MCFC.
Component
Material
Area
(cm2)
Thickness
(mm)
Porosity
(%)
Anode
Cathode
Matrix
Ni-Cr
Ni
aeLiAlO2
25.5
25.5
50.24
0.475
0.48
0.90e0.98
66.78
64.78
50.6
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with CuKa radiation (l ¼ 1.54059 Å) source at 40 kV and 40 mA.
Unfortunately, for its XRD analysis, no crystalline peaks
(2q ¼ 5 w8 , 20 w25 ) of ZSM-5 zeolite were observed [17,18].
The main reason is that the amount of “shell” is not enough to
detect, which implied that the “shell” was quite thin.
The stable methane conversion of the coreeshell catalyst
implied that the catalyst was suited to be applied in DIR-MCFC
and was provided with better capability of anti-poison to
alkali vapor. As mentioned above Knudsen diffusion could be
key step in the mass transfer processes in which Graham’s
law [19] could be applied. The law states that the ratio of
effusion rate of gas 1 to that of gas 2 is inversely proportional
to the square root of their molecular weight, written as follows
Rate 1=Rate 2 ¼
Fig. 1 e Contrast of methane conversion of catalysts’ SRM
reaction with different treatment methods at 923 K. (,)
non-posioned Ni/Al2O3 (B) posioned Ni/Al2O3 (6) posioned
sil-1/Ni/Al2O3.
Sil-1 seeds layer was 5.1e5.6Å, which could be smaller than
the molecular dynamic diameters of CH4, H2O, H2, CO and CO2
in this system (3.82, 2.7e3.2, 2.89, 3.76 and 3.3Å, respectively.
Calculated using Chem 3D Ultra version 9.0 [16]). The Knudsen
diffusion could be considered as the key step of the mass
transfer in the catalytic reaction processes. The gases of
methane and water molecules passed through the pores by
hitting the walls of the pores which pushed the molecules
progressively, arrived at catalytic sites and reacted. The
reaction products of hydrogen, carbon monoxide and carbon
dioxide moved out of the pores by the Knudsen diffusion.
However, the diffusion rate of the reactive gases were slowed
due to the exist of the shell. And the SRM reactive rate also
became a little slower. That is to say, the shell slowed the SRM
reactive rate while protected the core from alkali-poisoning.
So the methane conversion decreased from 80% (no shell
catalysts) to 62% (coreeshell catalysts) in Fig. 1.
As shown in Fig. 4, the thickness of the shell was 3.5 um,
and coated on the surface of the Ni-based catalyst tightly. In
order to confirm the structures of the shell, the coreeshell
catalysts powder X-ray diffraction (XRD) patterns was recorded using a PANalytical X’Pert PRO X-ray power diffractometer
pffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
M2=M1
(1)
Rate 1 is the effusion rate of gas 1; Rate 2 is the effusion rate of
gas 2. M1 is the molar weight of gas 1; M2 is the molar weight
of gas 2.
In the test, the multi-component gas mixture was simplified as binary system in order to explain the alkali-poisoning
resistance mechanism. The gas 1 was mixture gas
(0.37H2 þ 0.10CH4 þ 0.40H2O þ 0.086CO2 þ 0.040CO), gas 2 was
the vapor of molten carbonate (0.62Li2CO3 þ 0.38K2CO3),
according to the Graham’s law, the calculated result being
Rate 1/Rate 2 z 3.
This result indicated that the effusion rate of alkali vapor
through the micropores in the catalyst was much slower than
that of the mixture gas, and the most alkali vapor was separated out of micropores in the catalyst. In addition, as known
to all, the adsorption coefficient of silicate-1 zeolite to alkali
vapor (gas 2) was bigger than the mixture gas (gas 1). If the
adsorption coefficient was also considered, the Knudsen
diffusion rate ratio of the two gases would become much
bigger. Unfortunately, the adsorption coefficient of silicate-1
zeolite to alkali vapor was difficult to find. However, it could
be also suggested that the coreeshell Ni-based catalyst
showed good alkali-resistance performance.
3.2.
Unit cell test
In order to investigate the effect of electrolyte on the performance of DIR-MCFC, the single cell was assembled and its
initial performance and durability of 100 h test were shown in
Fig. 5 and Fig. 6 respectively.
Fig. 2 e Alkali vapor treatment apparatus of catalysts and coreeshell catalysts.
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Fig. 3 e The principle of alkali-resistance and the structure of coreeshell catalystethe micropore model of the catalyst.
As shown in Fig. 5, the open circuit potential of the cell rose
from 1.138 to 1.167 V when the reactive gas pressure varied
from 0.1 to 0.4 MPa. At 150 mA cm2, the cell voltage increased
from 0.721 to 0.864 V, indicating that the increment of the
reactive gas pressure promoted the cell performance. Li et al.
[12] also evaluated the performance of DIR-MCFC unit cell. The
output voltage kept about 0.77 V when the current density was
150 mA cm2. However, the operation pressure was not
mentioned in the paper. We tested the performance of DIRMCFC unit cell at different operation pressures and found
that the cell performance raised with the increment of operation pressure. This phenomenon could be explained as
below.
According to the Nernst Equation (2) of electrode reaction
written as follow [20]
E ¼ E0 þ
1=2
RT pH2 pO2
RT pcCO
þ ln a 2
ln
pH2 O
2F
2F pCO2
(2)
E0dthe standard potential of fuel cell, V; Rdideal gas
constant, its value equals to 8.314, J mol1 K1; Tdabsolute
temperature, K; Fdfaraday constant, its value equals to 96500,
C mol1; pdabsolute pressure, Pa; superscript c represents
cathode, a represents anode.
According to the above Equation (2) of electrode reaction,
the increment of reactive gas pressure was in favor of the cell
potential. Further, the increment of reactive gas pressure was
helpful for the mass transfer, which accordingly favored the
processes of electrode reactions and increased the performance of DIR-MCFC.
With the reactive gases at 0.2 MPa and steam to carbon
ratio of 2:1(S/C ¼ 2), the 100 h durability test of DIR-MCFC was
carried out at 150 mA cm2(see Fig. 6). As shown in Fig. 6, the
cell voltage varied in the range between 0.751 and 0.826 V. The
cell voltage experienced three stages: decreasing, increasing
and stable stage. Specifically, the cell voltage varied from 0.782
to 0.750 V at the decreasing stage (0e4 h), from 0.750 to 0.826 V
at the increasing stage(4e17 h), from 0.826 to 0.751 V quite
slowly at the stable stage(17e100 h). This phenomenon was
due to two primary factors: the change of the matrix structure
and the slight alkali-poisoning of the catalyst.
Specifically speaking, in the first stage, the hydrated water
in the matrix was prone to lose at about 650 C by Equation (3)
as fellows [21]
Fig. 4 e SEM images of Sil-1 seeds layer of the coreeshell Ni-based catalyst. (a) SEM image of Sil-1 seeds layer coated with
the catalyst. (b) SEM image of the thickness of the Sil-1 seeds layer coated with the catalyst.
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1.2
180
1.2
160
1.1
140
1.1
Initially
After 100h
120
0.9
0.8
100
80
60
1.0
U(V)
0.1MPa
0.2MPa
0.3MPa
0.4MPa
P(mW cm-2)
U(V)
1.0
0.9
0.8
40
0.7
20
0.6
0
20
40
60
80
0.7
0
100 120 140 160 180 200 220 240 260
0.6
j(mA cm-2)
0
Fig. 5 e The performance of the single cell with different
pressures anode gas: CH4:H2O [ 100:200; cathode gas:
O2:CO2 [ 80:120.
LiAlO2 $nH2 O/LiAlO2 þ nH2 O
(3)
0.9
0.8
U(V)
0.7
0.6
0.5
0.4
0.3
0.2
0.1
20
30
40
50
60
70
80
90
100
t(h)
Fig. 6 e The durability of 100 h test of the single cell. P:
0.2 MPa; anode gas: CH4:H2O [ 100:200; cathode gas:
O2:CO2 [ 80:120.
200
Fig. 7 e The EDX analysis of the coreeshell catalyst after
100 h test.
1.0
10
150
j(mA cm )
1.1
0
100
-2
Then the lost water reacted with Li2CO3 to produce Li2O
whose melt point is higher than 1432 C [22], which blocked
the pores in the matrix. Accordingly, the matrix conductivity
decreased owing to the change of the electrolyte composition
and some blocked pores in the matrix. Thus, the cell voltage
dropped at the first stage. Simultaneously, the migrated
amounts of the electrolyte from cathode to anode decreased
due to the blocked pore, and also the amounts of alkali that
the coreeshell catalyst adsorbed reduced. As a result of which,
the cell showed stable performance. Along with the reaction,
the CO2 accumulated at the surface of cathode and matrix,
Li2O reacted with CO2 and changed back into Li2CO3 gradually
[22], and the blocked pores were released. On the other hand,
the electrolyte was well-distributed on the effect of reactive
gas pressure, and the cell voltage rebounded to 0.826 V.
0.0
50
As shown in Fig. 7, the cell voltage changed from 0.788 to
0.755 V at 150 mA cm2 after the 100 h operation. The 33 mV
difference suggested that the coreeshell Ni-based catalyst
exhibited good alkali-resistance ability. The role mechanism
of coreeshell Ni-based catalyst was demonstrated by
the micropore model of the catalyst as shown in Fig. 3.
According to Graham’s law, in the same manner managing
the complicated system in DIR-MCFC as a simple one in which
only two gases contained, gas1 was the mixture gas
(H2 þ CH4 þ H2O þ CO2 þ CO), gas 2 was the vapor of molten
carbonate (0.62Li2CO3 þ 0.38K2CO3). The calculated values of
Rate 1/Rate 2 were shown in Table 2, as indicated in the Table,
the calculated results being Rate 1/Rate 2 z 3 under the
conditions of run on at 150 mA cm2 and open circuit of DIRMCFC. It illustrated obviously that the effusion rate of molten
carbonate vapor was much slower than that of the mixture
gas through the micropores in the catalyst through which the
most vapor of molten carbonate couldn’t pass to arrive at the
active site of the catalyst in which some zigzags enhanced the
passing difficulty of molten carbonate vapor through the
micropores in the catalyst because of its bigger molecules. The
catalyst could suffer from slight poison with molten carbonate
vapor, holding the comparatively higher and stable activity for
the methane steaming reforming reaction. So the catalyst
played an important role in alkali vapor resistance, which was
also explained by micropore model of the catalyst as above.
After 100 h test, the EDX analysis of the coreeshell catalyst
in unit cell was preceded. As shown in Fig. 8, the amount of
potassium atom was 0.47%, lithium atom was not found in the
coreeshell catalyst. Finally, the voltage of the single cell began
decreasing very slowly owing to the slight alkali-poison of the
coreeshell catalyst and the slight loss of the electrolyte.
3.3.
Short stack test
A short stack (three cells) was assembled and the stack
performance was shown in Fig. 9. The assembly of the short
stack was different from that of the single cell owing to the
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Table 2 e The values of Rate 1/Rate 2 under the conditions of run on at 150 mA cmL2 and open circuit for DIR-MCFC.
g1 (the mixture gases)
g2 (molten carbonate vapor)
0.48H2 þ 0.12CH4 þ 0.24H2O þ 0.074CO þ 0.086CO2
0.30H2 þ 0.17CH4 þ 0.43H2O þ 0.030CO þ 0.070CO2
M2/M1
0.62Li2CO3 þ 0.38K2CO3
0.62Li2CO3 þ 0.38K2CO3
Rate 1/Rate 2
Conditions
z3
z3
O.C.V
150 mA cm2
98/13
98/15
Fig. 8 e The performance comparison of the single cell initially and after 100 h. P: 0.2 MPa; anode gas: CH4:H2O [ 100:200;
cathode gas: O2:CO2 [ 80:120.
increased number of matrix. The differences of the stacking
pressures were shown in Fig. 10 during their first start-ups.
As shown in Fig. 9, under the conditions that S/C was 2 and
current density was 150 mA cm2, the output voltage varied
from 2.079 to 2.256V when the reactive gas pressure rose from
0.1 to 0.3 MPa. Yoshiba et al. [23] assembled one 10 kW-class
stack, which point out that the output voltage of the stacks
was around w0.8 V at an operating current density of 150 mA/
cm2. Owing to the different fuel gases (H2) and higher operating pressure, the performance of the stacks is better than
ours. The maximal output power density of our short stack
was 338.4 mW cm2. The short stack performance also
increased along with elevating the reactive gas pressure
3.4
350
3.2
300
3.0
250
6.0
5.5
200
150
100
2.4
6.5
50
2.2
20
40
60
80
100
120
140
160
4.5
4.0
3.5
0
3.0
-50
2.5
2.0
0
5.0
F(t)
U(V)
2.6
7.0
P(mW cm-2)
0.1MPa
0.2MPa
0.3MPa
2.8
owing to the same reasons as that in the unit cell. It was
implied that the catalytic activity on the catalyst was as high
as that in the unit cell.
As shown in Fig. 10, at the beginning of the processes of
burning matrices (the first start-ups), the stacking pressure of
the single cell and the short stack were 47.0 and 89.0 kg cm2
respectively. The change of stacking pressure of the short stack
along with the temperature was different from that of the single
cell. For the short stack, the stacking pressure changed very
slowly. However, the stacking pressure changed very quickly for
the unit cell. The differences were resulted from the number of
the matrix. During the first start-up of unit cell, the change of
stacking pressure indicated above was affected by the shrink of
j(mA cm-2)
Fig. 9 e The performance of the short stack with different
pressures anode gas: CH4:H2O [ 300:600; cathode gas:
O2:CO2 [ 200:300.
2.0
short stack
single cell
0
100
200
300
400
500
600
700
Fig. 10 e The comparison of stacking pressures change of
the single cell and the short stack along with temperature.
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the matrix brought about on burning matrix in the temperature
range from room temperature to 400 C, and the thermal
expansion of the steel components [24] in the temperature
range from 400 to 650 C. As a result, the stacking pressure for
the unit cell increased at the beginning.
3.4.
The effect of reactive gas pressure on the
performance of DIR-MCFC
The SRM reaction and water-gas shift reaction equations were
listed as follows [25]
CH4 þ H2 O ¼ CO þ 3H2
CO þ H2 O ¼ CO2 þ H2
DH0298 ¼ 206kJ=mol
DH0298 ¼ 41kJ=mol
(4)
(5)
In the light of thermodynamic principle, the increment of
reactive gas pressure went against the process of Equation (4).
If carbon monoxide produced from Equation (4) became less,
the process of Equation (5) would be affected. In one word, the
increment of reactive gas pressure went against the SRM
reaction.
According to the Nernst Equation as above, the performances of the unit cell and the short stack were increased
along with elevating reacting gas pressure, which indicated as
above the increment of reactive gas pressure improved the
processes of electrode reactions in the unit cell and the short
stack, so their performances were increased in sequence. The
SRM reaction was conjugated with the anodic reaction in the
unit cell and the short stack worked on at higher current
density especially, the increment of reactive gas pressure
made for the processes of electrode reactions, significantly
made for those of cathode reactions, at the same time, which
could make for the processes of SRM reaction. Because a big
amount of hydrogen was consumed by the unit cell and the
short stack at higher current density, the SRM reactions could
be promoted forward smoothly under higher reactive gas
pressure, along with which, the performances of the unit cell
and the short stack were getting higher. The results above also
illustrated that the coreeshell Ni-based catalyst possessed
good alkali-poisoning resistance.
4.
Conclusion
The sort of coreeshell catalyst as a novel anti-alkali-poisoning
concept was proved feasible, which supplied a new way to
solve the alkali-poisoning problem in DIR-MCFC. The coreeshell
catalyst was applied to the unit cell and the short stack
successfully. Under the conditions that pressure was 0.2 MPa
and S/C was 2, the potential of the cell could keep above 0.75V at
150 mA cm2 during 100 h test, the initial maximum output
power density was 165.25 mW cm2. The maximal output
power density of the short stacks was 338.4 mW cm2.
Acknowledgments
This work was financially supported by Chinese Ministry of
Science (nos. 2007AA05Z137).
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