Design and construction of Ni3-: XCoxO4 nanorods grown on Ni foam for tuning synthetic natural gas heating values

Article abstract of DOI:10.1039/c7nj03904b

Ni_3-xCo_xO₄ nanorods with different Ni/Co ratios were fabricated on Ni foam using a controllable process. The conversion of CO for Ni₂CoO₄ nanorods was the highest during the whole methanation reaction process. The design of the Ni_3-xCo_xO₄ nanorods with different Ni/Co ratios is the origin of the different catalytic activity. The synergistic effect of Ni and Co also tunes the product selectivity, thus controlling the heating value of synthetic natural gas. The nanorods directly grown on the Ni foam can ensure efficient anchoring of the nanorods. The designed synthesis of the Ni_3-xCo_xO₄ nanorods with different Ni/Co ratios provides a new strategy for controlling the catalytic activity and selectivity of syngas methanation.

Full text of DOI:10.1039/c7nj03904b

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Jason B. Benedict et al.
The role of atropisomers on the photo-reactivity and fatigue of
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Design and construction of Ni Co O nanorods grown on Ni foam
3-x
x
4
for tuning synthetic natural gas heating value
Received 00th January 20xx,
Accepted 00th January 20xx
Jiaqiang Sun, * Zheng Chen, Yingying Xue, and Jiangang Chen*
DOI: 10.1039/x0xx00000x
The Ni3-xCo
conversion of CO for Ni
the Ni3-xCo nanorods with different Ni/Co ratio is the origin of the different catalytic activity. The synergetic effect of Ni
and Co also tunes the product selectivity, and thus controlling the heating value of synthetic natural gas. The nanorods
directly grown on the Ni foam can ensure efficient anchoring of the nanorods. The designed synthesis of the Ni3-xCo
x
O
4
nanorods with different Ni/Co ratio have been fabricated on Ni foam by a controllable process. The
2
CoO nanorods was the highest during the whole methanation reaction processing. The design of
4
www.rsc.org/
x
O
4
x 4
O
nanorods with different Ni/Co ratio provides new strategy for controlling the catalytic activity and selectivity of syngas
methanation.
3
the conversion of coke oven gas (21.2 MJ/Nm ) into high-
3
11
1
. Introduction
calorie SNG (41.9 MJ/Nm ) on a fluidized bed reactor. It is
noted that syngas methanation is a strongly exothermic
process and undesired hotspots often arise in the reactor bed,
which makes the temperature-control difficult and even
Methanation is a chemical process used to generate methane
from a mixture of hydrogen and carbon monoxide (syngas),
which can be derived from non-petroleum feedstocks such as
1
2
1
,
2
shortens the catalyst lifetime. Although various technologies
are proposed for solving the limitation of heat transfer, some
other challenges arise simultaneously. Thus, designing and
synthesizing novel catalysts with high reactivity and stability
for developing an energy-efficient SNG process is particularly
desirable. Metal foam catalysts with inherent outstanding
features such as interconnected porous structure, favourable
mass/heat transfer, low pressure drop and desired mechanical
robustness, have been attracting growing interests in
coal, biomass and even coke oven gas.
Previously,
methanation reactions were used for the removal of carbon
monoxide from feed gas in ammonia synthesis. Production of
synthetic natural gas (SNG) by syngas methanation has been
considered as a promising way towards the sustainable
3
development and clean utilization of coal.
Recently,
methanation has received attention in the production of high
4
, 5
calorie SNG. The traditional catalyst for methanation is
supported nickel catalysts. Various supported nickel catalysts
1
3, 14
6
-
heterogeneous catalysis.
The metal foams are opening an
have been explored extensively for the methanation process.
8
opportunity on the development of novel catalyst and reactor
technology for the SNG process from syngas, but effective and
efficient non-coating method for placing catalytic active sites
onto the surface of metal foam is particularly desirable and is
Nickel still has a high activity and a comparatively low price,
but nickel catalysts yield nearly pure methane gas as the
product and so the heating value of the product gas is
9
considerably low. In order to extend the application of
1
5, 16
still a significantly challenge.
The development of
natural gas as town gas, it is extremely important to improve
the heating value. To achieve a high heating value, a proper
amount of C2-4 paraffins, which have greater heating values
than methane, must be formed during the methanation
process. Therefore, selectivity control is one of the key
challenges of research into methanation. So the methanation
catalyst should be modified by the Fischer–Tropsch (FT)
catalysts in a controlled manner. Cobalt catalysts are generally
more selective to linear longchain hydrocarbons, which have
nanotechnology in recent decades brings new opportunities in
1
7, 18
the exploration of high-performance catalysts.
Herein, we report controllable synthesis of the Ni3-xCo
x 4
O
nanorods grown on Ni foam via a hydrothermal process of
precursor and subsequent thermal decomposition. The Ni3-
x
x 4
Co O nanorods with different Ni/Co ratios were studied in
the syngas methanation reaction. The activities of the catalysts
were evaluated in terms of CO conversion, C2–4 selectivity and
heating value based on the produced hydrocarbons. The
1
0
been employed in industry for FT synthesis.
Researchers
x 4
designed synthesis of the Ni3-xCo O nanorods with different
2 3
found that Co–Mn–Ru/Al O showed the best performance in
Ni/Co ratios provides new strategy with an aim at controlling
the catalytic activity and selectivity for syngas methanation.
State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese
Academy of Sciences, Taiyuan, 030001, China
E-mail: chenjg@sxicc.ac.cn; sunjiaqiang@sxicc.ac.cn.
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temperature and the hydrogen consumption was recorded
using a thermal conductivity detector (TCD).
2
. Experimental
2
.1 Catalyst Preparation
A mixture of Co(NO •6H
concentration, 0.1 M; [Ni ]/[Co ] =0, 0.5, 1.0, 2.0 or 0.1M
2
.3 Catalytic Reaction
The catalytic behaviour was investigated in a fixed bed reactor.
The reactor can be supplied with H , synthesis gas (nH2/nCO=2).
3
)
2
2 3 2 2
O, Ni(NO ) •6H O (metal ions total
2
+
2+
2
+
2
2 2
Ni ) and 50 mmol of CO(NH ) were dissolved in 100 mL of
The gas flow is controlled by Brooks 5850E mass flow
controllers (MFC). The pressure is controlled via a back
pressure regulator. The reaction products pass a 130 °C hot
trap and a 5 °C cooling trap at working pressure and can be
measured online by a GC. After in-situ reduction, the reactor
was cooled to 50 °C, the synthesis gas (nH2/nCO=2, GHSV = 5
L/h/g) was fed into the catalysts bed and the temperature was
increased at 1.0 °C/min heating rate to 300 °C. During testing,
the pressure of synthesis gas was maintained at 2.0 MPa. The
reaction rates and hydrocarbon selectivity were evaluated
after 24 h on-stream. The gaseous reaction products were
analysed on-line by gas chromatography (GC 920).
water under magnetic stirring. The homogeneous solution
prepared above was transferred directly into a 200 mL Teflon-
lined stainless steel autoclave. The Ni foam (1 g) was carefully
cleaned with HCl (1 mol/L), absolute ethanol, and distilled
water, and immersed in the homogeneous solution. The
autoclave was sealed and maintained at 120 °C for 8 h and
then allowed to cool down to room temperature naturally. The
catalysts grown on Ni foam was washed several times with
distilled water, dried at 80 °C for 4 h, and calcinated at 400 °C
for 4 h in air, but the NiO precursor was calcinated in N
Finally the produced catalysts were reduced at 500 °C and 0.2
MPa for 4 h by H with a gas hourly space velocity (GHSV) of 10
L/h/g in a fixed-bed reactor.
.2 Characterization
In order to characterize the catalysts, the samples were
prepared by scraping the Ni3-xCo from the Ni foam. Powder
X-ray diffraction (XRD) was performed on a Shimadzu XRD-
2
.
2
2
3
. Results and discussion
x 4
O
6
000 diffractometer with Cu Kα radiation (
λ= 1.5418 Å) in the
θ range from 10° to 70°. The morphology and size of as-
2
synthesized samples were monitored by using a scanning
electron microscope (SEM, Zeiss Supra 55). The structure and
composition of the products were characterized by means of a
high-resolution transmission electron microscope (HRTEM,
JEM 2100F) and energy dispersive X-ray spectroscopy (EDS).
The surface area was determined by BET (Brunauer–Emmett–
Teller) measurements using a Tristar
analyser. The precursor (50 mg) was placed in a quartz reactor
and was reduced by a 5% H /N gas mixture at a flow rate of
0 mL/min, as the TPR experiments were performed. The
2
Ⅱ3020 N adsorption
2
2
5
temperature was ramped at 10 °C/min to the final
x 4
Figure 1 XRD patterns of the Ni3-xCo O nanorods with different Ni/Co ratio.
3 4 2 4 4 2 4
Figure 2 SEM images of the catalysts formed on the Ni foam with different Ni/Co ratio: Co O (a, b), NiCo O (c, d), Ni1.5Co1.5O (e, f), Ni CoO (g, h) and NiO (i, j).
2
| J. Name., 2012, 00, 1-3
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The Ni3-xCo
stepwise transformation process based on fabrication of the tip of the Ni3-xCo
hierarchical Co3-x Fe nanowire arrays on an iron substrate. that, a large number of cracks and pores exist on the surface of
A piece of nickel foam was immersed in a solution the nanorods. HRTEM were used to further confirm the phase
O
x 4
nanorod arrays on Ni foam were achieved by a and 2μm, respectively. Figure 3 displays TEM images of near
x 4
O
nanorods, from which we can find
x
O
4
1
9, 20
2
+
2+
containing a mixture of Co and Ni ions and urea. First, by of the nanorods. Figure 3b shows a HRTEM image taken from
using urea as the mineralizer and undergoing an easily the Co nanorod, which indicates a lattice spacing of 0.286
controllable hydrothermal process, a thin film of precursor has nm, corresponding to the (220) crystal planes of Co , in good
been successfully attained on Ni foam. Second, after the agreement with the original XRD pattern in Figure 1. The
3 4
O
3 4
O
o
adequate pyrolysis of precursors at 400 C in air or N
nanorod arrays can be obtained with a robust NiCo
mechanical adhesion to the Ni foam. Figure 1 show the XRD NiCo
2
for 4 h, interplanar spacing of 0.287 nm was detected for an individual
Ni3-xCo
x
O
4
2
2
O
O
4
nanorod, corresponding to the (220) crystal planes of
(Figure 3d). As shown in Figures 3f, an interplanar
4
patterns of the as-prepared samples. All the diffraction peaks spacing of 0.203 nm was detected for an individual nanorod,
of Co can be indexed to cubic phase, which is consistent corresponding to the (400) crystal planes of Ni1.5Co1.5 . The
with the value in the standard card (JCPDS Card No. 43-1003). interplanar spacing of 0.288 nm was detected for an individual
3
O
4
O
4
All the diffraction peaks of NiCo
2
O
4
can be indexed to cubic Ni
2
CoO
CoO
4
nanorod, corresponding to the (220) crystal planes of
(Figure 3h). The interplanar spacing of 0.241 nm was
phase, which is consistent with the value in the standard card Ni
2
4
(
JCPDS Card No. 20-0781). With the increasing of Ni/Co ratios, detected for an individual NiO nanorod, corresponding to the
all the peaks of Ni1.5Co1.5 and Ni CoO have slightly smaller (111) crystal planes of NiO (Figure 3j). The EDS was conducted
θ values compared with the XRD pattern of NiCo , which in-situ with the HRTEM to analyze the composition of the Ni3-
can be attributed to the substitution of some of the cobalt ions Co nanorods (Figure 4). The Ni3-xCo nanorods contained
by nickel in Ni3-xCo . Furthermore, all the diffraction peaks of Co, Ni and O atoms, which shows the atomic ratio of Ni/Co of
NiO also can be indexed to cubic phase, which is consistent NiCo and Ni CoO nanorods to be around 0.66,
with the value in the standard card (JCPDS Card No. 47-1049). 1.00 and 2.10, respectively.
The SEM images in Figure 2 clearly show the morphology of The reduction behavior of the Ni3-xCo
the Ni3-xCo nanorods directly grown on the Ni foam. The investigated by H -TPR and the profiles are shown in Figure 5.
gathered Ni3-xCo nanorod arrays with a relatively high There are two peaks in the temperature range between 150 °C
density are obviously observed, especially, the NiO possess and 450 °C for Co . The smaller peak centered at 230 °C can
rod-on-sheet architecture. According to the high-magnification be attributed to the reduction process of Co to Co . The
images, the average diameter and length of the Ni3-xCo larger peak centered at 335 °C can be attributed to the
nanorods with a sharp tip are estimated to be about 100 nm reduction of Co to Co .
O
4
2
4
2
2 4
O
x
O
x 4
x 4
O
x 4
O
2
O
4
, Ni1.5Co1.5
O
4
2
4
x 4
O nanorods was
x
O
4
2
x 4
O
3 4
O
3
+
2+
x
O
4
2
+
0
Figure 3 TEM (a) and HRTEM (b) images of the Co
O
3 4
nanorods; TEM (c) and HRTEM (d) images of the NiCo
2 4 4
O nanorods; TEM (e) and HRTEM (f) images of the Ni1.5Co1.5O
nanorods; TEM (g) and HRTEM (h) images of the Ni CoO
2
4
nanorods; TEM (i) and HRTEM (j) images of the NiO nanorods.
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2 x 4
Figure 5 H -TPR profiles of the Ni3-xCo O nanorods with different Ni/Co ratio.
Figure 6 Nitrogen adsorption–desorption isotherms (a) and pore size distributions (b)
of the Ni3-xCo nanorods with different Ni/Co ratio.
x 4
O
3
+
3+
2+
2+
Figure 4 EDS spectra of NiCo
2
O
4
(a), Ni1.5Co1.5
O
4
(b) and Ni
2
CoO
4
(c) nanorods.
of Co , Ni , Co and Ni , respectively. For the NiO nanorods,
there is only one peak centered at 395 °C, which can be
There are four peaks in the temperature range between 150 °C
and 450 °C for NiCo O Ni1.5Co1.5O and Ni CoO . They are
2+
0
attributed to the reduction process of Ni to Ni .
adsorption-desorption isotherms measurements were used
to determine the specific surface area, average pore size and
pore volume of the Ni3-xCo nanorods. Figure 6 shows the N
adsorption-desorption isotherms and the corresponding pore
size distributions of the Ni3-xCo nanorods. The BET surface
areas of Co , NiCo , Ni CoO and NiO
nanorods were calculated to be 62.2 m /g, 64.7 m /g, 79.9
2
4,
4
2
4
N
2
distinguished corresponding to the consecutive stepwise
3
reduction of Co , Ni , Co and Ni . For the NiCo O
+
3+
2+
2+
2
4
O
x 4
2
nanorods, the peak centered at 265 °C can be attributed to the
3
reduction process of Co to Co ; the peak centered at 303 °C
+
2+
x 4
O
3
+
2+
can be attributed to the reduction process of Ni to Ni ; The
peak centered at 373 °C can be attributed to the reduction of
3
O
4
2
O
4
, Ni1.5Co1.5
O
4
2
4
2
2
2
Co to Co ; The peak centered at 423 °C can be attributed to
+
0
2
2
2
m /g, 62.6 m /g and 62.5 m /g, respectively. The total pore
volumes of Co , NiCo , Ni CoO and NiO
nanorods were calculated to be 0.31 cm /g, 0.26 cm /g, 0.32
2
+
0
the reduction of Ni to Ni . With the increase of Ni and Co
ratios, the reduction peak shifted slightly to lower
3
O
4
2
O
4
, Ni1.5Co1.5
O
4
3
2
4
3
temperature. For the Ni1.5Co1.5O nanorods, there are two
4
3
3
3
cm /g, 0.21 cm /g and 0.20 cm /g, respectively. The pore size
distribution curves of the Ni3-xCo nanorods derived from
peaks centered at 245 °C and 270 °C can be attributed to the
3
x 4
O
+
3+
reduction process of Co and Ni ; while the larger peak
centers at 341 °C and 392 °C can be attributed to the reduction
the desorption branches using the Barett-Joyner-Halenda
model. It can be clearly seen that the pores centered at around
2
process of Co and Ni , respectively. For the Ni CoO
+
2+
2
4
1
7 nm, 9 nm, 8 nm, 7 nm and 4 nm were attributed to the
mesoporous of Co , NiCo , Ni CoO and NiO
nanorods, respectively (Fig. 6b).
nanorods, there are two smaller peaks centered at 228 °C and
48 °C, and two larger peak centered at 319 °C and 381 °C,
3
O
4
2
O
4
, Ni1.5Co1.5
O
4
2
4
2
corresponding to the reduction
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Figure 7 CO conversion profiles of NiCo
2
O
4
(a), Ni1.5Co1.5
O
4
(b) and Ni
2
1
CoO
4
(c) nanorods. nanorods, 47.0% over Ni CoO nanorods and 42.3% over NiO
2 4
-
-1
Reaction conditions: catalyst 1.0 g P=2.0 MPa, H
2
/CO=2, GHSV=5 L·g ·h
nanorods at 300 °C, respectively.
At the same reaction conditions, with the increasing of mole
ratio of Ni and Co, the CO conversion increased obviously,
indicting that Ni specie is more active than Co spices for CO
2
1
methanation reaction.
influence factor among other factors for catalyst. At 400 °C,
Co , NiCo , Ni CoO and NiO nanorods
showed the highest conversion of CO, which was 71.7%,
0.6%, 94.2%, 97.9%, and 95.7%, respectively. The conversion
of CO for Ni CoO nanorods was the highest during the whole
The Ni content is a significant
2
2
3
O
4
2
O
4
, Ni1.5Co1.5O
4
2
4
9
2
4
reaction processing, which might be mainly attributed to the
synergetic effect between Ni and Co. The design of the Ni3-
x
Co
different catalytic activity. The selectivity (expressed as mol%
without CO ) of the Ni3-xCo nanorods with temperature on
stream are shown in Figure 8 and Figure 9. The Ni3-xCo
nanorods catalysts mainly produce light alkane. CH and C
are the main component in the hydrocarbon products. It can
be seen that the CH selectivity of Co nanorods is 54.3% at
00 °C; The CH selectivity of NiCo nanorods is 67.9% at 300
C, when further increasing Ni proportion, the CH selectivity
nanorod catalysts increases to 81.9% at 300
selectivity of Ni CoO nanorods is similar with that
nanorods at 300 °C. While the CH selectivity of
NiO nanorods is 75.6% at 300 °C, which is lower than that of
and Ni CoO nanorods. The selectivity of CH over
all the catalysts except for Ni CoO increases slightly with
increasing reaction temperature. With the increasing of
temperature, the selectivity of CH is up to 90% over
nanorods. The Co nanorods show the lowest
selectivity compared with the bimetallic catalysts and NiO
at all the temperature ranges. Figure 9 shows C2-4 selectivity
x 4
O nanorods with different Ni/Co ratio is the origin of the
2
x 4
O
x 4
O
2 4
-
Figure 8 CH
4
x 4
selectivity profiles of the Ni3-xCo O nanorods catalysts with different
4
-
1
-1
Ni/Co ratio. Reaction condition: catalyst 1.0 g P=2.0 MPa, H
2
/CO=2, GHSV=5 L·g ·h
4
3 4
O
3
4
2 4
O
°
4
of the Ni1.5Co1.5O
4
°
C. The CH
4
2
4
of Ni1.5Co1.5
O
4
4
Ni1.5Co1.5
O
4
2
4
4
2
4
4
Ni1.5Co1.5
O
4
3 4
O
CH
4
profiles of the Ni3-xCo nanorods catalysts with different
x
O
4
3 4
Ni/Co ratio. The Co O nanorods show the highest C2-4
Figure 9 C2-4 selectivity profiles of the Ni3-xCo
x 4
O nanorods catalysts with different Ni/Co
-
1
-1
selectivity at 300 °C. When further decreasing Co proportion,
the C2-4 selectivity of the bimetallic catalysts decreases and the
ratio. Reaction condition: catalyst 1.0 g P=2.0 MPa, H
2
/CO=2, GHSV=5 L·g ·h
Ni
be seen that C2-4 selectivity of Ni
NiO above 320 °C. Furthermore, the selectivity of C5+ over all
of the Ni3-xCo nanorods is very low.
The SNG calorie produced from Co
Ni CoO and NiO nanorods was calculated (Table 1), with the
heating value of 62.4 MJ/Nm , 56.6 MJ/Nm , 44.0 MJ/Nm ,
2
CoO
4
catalyst shows the lowest selectivity at 300 °C. It can
x 4
Figure 7 shows the catalytic performance of the Ni3-xCo O
CoO is similar with that of
4
nanorods with different Ni/Co ratio for the syngas
methanation. It can be seen from Figure 7 that the conversion
of CO over the catalyst increases with increasing reaction
temperature. A significant difference in CO conversion was
2
x
O
4
3 4 2 4 4
O , NiCo O , Ni1.5Co1.5O ,
observed in the Ni3-xCo
catalysts, Co nanorods exhibit the lowest activity and the
CO conversion is 3.5% at 300 °C. However, the CO conversion
is 6.8% over NiCo nanorods, 21.6% over Ni1.5Co1.5
x 4
O nanorods. Among the tested
2
4
3
3
3
3
O
4
3
3
5
0.0 MJ/Nm and 48.3 MJ/Nm , respectively. The highest
heating value of Co nanorods was ascribed to the highest
2+ hydrocarbons content.
3 4
O
2
O
4
O
4
C
Table 1. Product distributions of catalysts in methanation reaction.
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Catalysts
Q
CO conv.
(%)
Selectivity (%)
(
MJ/Nm3)
CH
4
C
2
H
6
C
3
H
8
C
H
4 10
C
5+
Co
3
O
4
62.4
56.6
44.0
50.0
48.3
71.7
90.6
94.2
97.9
95.7
60.6
69.4
90.3
80.0
83.6
17.4
15.5
6.8
11.5
8.5
1.8
5.5
4.0
7.8
4.6
0.9
1.8
2.6
2.7
2.0
0.2
1.4
0.6
NiCo
2
O
4
Ni1.5Co1.5
O
4
Ni
2
CoO
4
11.3
9.2
NiO
-
1
-1
2
Reaction conditions: catalyst 1.0 g T= 400 °C, P=2.0 MPa, H /CO=2, GHSV=5 L·g ·h
Figure 10 SEM images of Co
3 4 2 4 4 2 4 3 4 2 4 4
O (a), NiCo O (b), Ni1.5Co1.5O (c), Ni CoO (d) and NiO (e) nanorod catalysts after reduction; SEM images of Co O (f), NiCo O (g), Ni1.5Co1.5O (h),
Ni CoO (i) and NiO (j) nanorod catalysts after reaction.
2
4
the morphology after reduction, but the nanorods change into
small particles after reaction, duo to sintering in the reaction
process. The phase characterization of the catalysts used on
stream was examined by XRD (Figure 11). The cubic phase Co
appear in the XRD patterns for the Co
used, which is consistent with the value in the standard card
JCPDS 01-1260). The cubic phase Ni appear in the XRD
3 4
O nanorods catalysts
(
patterns for the NiO nanorods catalysts used, which is
consistent with the value in the standard card (JCPDS 15-0806).
The cubic phase CoNi appear in the XRD patterns for the
2 4 4 2 4
NiCo O , Ni1.5Co1.5O and Ni CoO nanorods catalysts used,
which is very similar to those of either fcc Ni (JCPDS 15-0806)
or fcc Co (JCPDS 01-1260) while a slight variation for the peak
position can be observed and all the peak positions lie
2
3, 24
between that of pure fcc Ni and pure fcc Co. (Figure 9).
Furthermore, the carbon peak appear in the XRD patterns for
NiCo , which is due to the coke in the
3 4 2 4 4 2 4
Figure 11 XRD pattern of Co O (a), NiCo O (b), Ni1.5Co1.5O (c), Ni CoO (d) and NiO(e)
nanorod catalysts used.
2 4 4
O and Ni1.5Co1.5O
suface of the catalysts, while there is no carbon peaks for
other catalysts. Experimental results have indicated that, the
syngas methanation proceed on metallic Ni species, which is
Figure 10 shows SEM images of Co
3 4 2 4 4
O , NiCo O , Ni1.5Co1.5O ,
Ni CoO and NiO nanorods after reduction and reaction. From
2
4
the images, it can be seen that there is no larger changing in
8
especially active in methanation.
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ARTICLE
In addition, there is currently a consensus in the literature that
Fischer–Tropsch synthesis proceeds on cobalt metal particles.
1
2
3
J. Kopyscinski, T. J. Schildhauer and S. M. A. Biollaz, Fuel,
010, 89, 1763-1783.
M. Gassnera and F. Maréchal, Energy Environ. Sci., 2012,
768-5789.
V. M. Lebarbier, R. A. Dagle, L. Kovarik, K. O. Albrecht, X. Li, L.
Li, C. E. Taylor, X. Bao and Y. Wang, Appl. Catal. B:Environ.,
2014, 144, 223-232.
M. Chen, J. Zhou, J. Zhang, J. Zhang, Z. Chen, J. Ding, F. Kong,
G. Qian and J. Chen, Appl. Catal. A:Gen., 2017, 534, 94-100.
H. L. Yong, D. W. Lee, H. Kim, H. S. Choi and K. Y. Lee, Fuel,
2
1
0, 20
5,
Therefore, the interaction between Ni and Co might
improve the adsorption and activation of CO and thus enhance
the methanation activity of the Ni3-xCo catalysts. The
5
x 4
O
formation of C2+ hydrocarbons is suppressed for nickel-based
catalysts, therefore the heating value of the product gas is
9
considerably low for nickel-based catalysts. But Co-based
4
5
6
7
8
9
1
1
1
catalysts are generally more selective to linear longchain
2
2
015, 159, 259-268.
J. Gao, Q. Liu, F. Gu, B. Liu, Z. Zhong and F. Su, Rsc Adv.,
2015, , 22759-22776.
5, 26
hydrocarbons.
In consequence, the synergetic effect of Ni
and Co tunes the product selectivity, and thus controlling the
heating value of the product. The nanorods directly grown on
the Ni foam can ensure efficient anchoring of the nanorods
and prevent leaching during catalytic reactions. Furthermore,
the spaces between neighboring nanorods are much larger,
which allows for easy gas diffusion and mass transport,
resulting in a high utilization of materials.
5
T. A. Le, M. S. Kim, S. H. Lee, T. W. Kim and E. D. Park, Catal.
Today, 2017, 293, 89-96.
H. Lu, X. Yang, G. Gao, J. Wang, C. Han, X. Liang, C. Li, Y. Li, W.
Zhang and X. Chen, Fuel, 2016, 183, 335-344.
C. Cheng, D. Shen, R. Xiao and C. Wu, Fuel, 2017, 189, 419-
427.
0 A. Y. Khodakov, W. Chu and P. Fongarland, Chem. Rev., 2007,
07, 1692-1744.
1
1 T. Inui, A. Sakamoto, T. Takeguchi and Y. Ishigaki, Ind. Eng.
Chem. Res., 1989, 28, 427-431.
2 S. Rönsch, J. Schneider, S. Matthischke, M. Schlüter, M. Götz,
Conclusions
J. Lefebvre, P. Prabhakaran and S. Bajohr, Fuel, 2016, 166
2
,
x 4
In summary, the Ni3-xCo O nanorods with different Ni/Co ratio
76-296.
3 J. A. Moulijn, M. T. Kreutzer, T. A. Nijhuis and F. Kapteijn, Adv.
Catal., 2011, 54, 249-327.
have been fabricated on Ni foam by a controllable process
involving the hydrothermal growth and calcinations of
1
x 4
precursor. The Ni3-xCo O
nanorods show different catalytic 14 R. J. Farrauto, Y. Liu, W. Ruettinger, O. Ilinich, L. Shore and T.
Giroux, Catal. Rev., 2007, 49, 141-196.
activity and selectivity in the syngas methanation reaction. It
can be found that the selectivity to methane increase at higher
1
1
5 Y. Li, Q. Zhang, R. Chai, G. Zhao, Y. Liu and Y. Lu,
Chemcatchem, 2015, 7, 1427-1431.
CO conversion levels for Ni1.5Co1.5
4 2 4
O nanorods. The Ni CoO
6 Y. Li, Q. Zhang, R. Chai, G. Zhao, F. Cao, L. Ye and L. Yong,
Appl. Catal. A: Gen., 2016, 510, 216-226.
heating value of product at 400 °C, which were 97.9% and 50.0 17 S. Liu, L. Hu, X. Xu, A. A. Al‐Ghamdi and X. Fang, Small,
nanorods showed the highest CO conversion and the suitable
3
2
015, 11, 4267.
8 Q. Wang, X. Wang, B. Liu, G. Yu, X. Hou, D. Chen and G. Shen,
J.Mater. Chem. A, 2013, , 2468-2473.
MJ/Nm . The synergetic effect of Ni and Co tuned the product
selectivity, and thus controlling the heating value of the
product. The present results suggest that specifically designed
1
1
1
9 J. Sun, Y. Li, X. Liu, Q. Yang, J. Liu, X. Sun, D. G. Evans and X.
Duan, Chem. Commun., 2012, 48, 3379-3381.
x 4
Ni3-xCo O nanorods with different Ni/Co ratios by controlling
synthesis parameters on Ni foam might bring new 20 J. Sun, S. Zheng, K. Zhang, D. Song, Y. Liu, X. Sun and J. Chen,
J. Mater. Chem. A, 2014, 2, 13116-13122.
opportunities for developing highly efficient catalysts.
2
2
1 M. A. Vannice, J. Catal., 1975, 37, 449-461.
2 S. Hwang, J. Lee, U. G. Hong, J. G. Seo, C. J. Ji, J. K. Dong, H.
Lim, C. Byun and I. K. Song, J. Ind. Eng. Chem., 2011, 17, 154-
1
57.
3 M. Cheng, M. Wen, S. Zhou, Q. Wu and B. Sun, Inorg. Chem.,
012, 51, 1495-1500.
4 X. W. Wei, X. M. Zhou, K. L. Wu and Y. Chen, Crystengcomm,
011, 13, 1328-1332.
Acknowledgements
2
2
2
This work was supported by the National Natural Science
Foundation of China (21503256, 21373254), the autonomous
2
research project of State Key Laboratory of Coal Conversion 25 Q. Zhang, J. Kang and Y. Wang, Chemcatchem, 2010,
SKLCC 2013BWZ004).
1058.
6 Q. Zhang, K. Cheng, J. Kang, W. Deng and Y. Wang,
Chemsuschem, 2014, , 1251-1264.
2, 1030-
(
2
7
Notes and references
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New Journal of Chemistry
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The table of contents entry
Design and construction of Ni Co O nanorods grown on Ni foam for tuning
3
-x
x
4
synthetic natural gas heating value
Jiaqiang Sun, * Zheng Chen, Yingying Xue, and Jiangang Chen*
Keyword (Ni Co O4, nanorods, tuning, heating value
)
3
-x
x
TOC figure
The Ni Co O nanorods with different Ni/Co ratio have been fabricated on Ni foam, which show
3
-x
x
4
excellent catalytic activity and can tune synthetic natural gas heating value.