Facile one-step synthesis of hierarchical porous carbon monoliths as superior supports of Fe-based catalysts for CO2 hydrogenation

Article abstract of DOI:10.1039/c5ra26009d

A versatile strategy involving one-step desilication of coke-deposited spent zeolite catalyst was successfully developed to prepare hierarchical porous carbon monoliths (HPCMs). Such a strategy avoids the use of hard or soft templates and carbon sources,

Full text of DOI:10.1039/c5ra26009d

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ARTICLE
Facile one-step synthesis of hierarchical porous
carbon monoliths as superior support of Fe-based
catalyst for CO2 hydrogenation
Cite this: DOI:
10.1039/x0xx00000x
Chengyi Dai,a Anfeng Zhang,a Min Liu,a Junjie Li,a Fangyu Song,a Chunshan
Songa,b* and Xinwen Guoa*
Received 00th January 2012,
Accepted 00th January 2012
A
versatile strategy involving oneꢀstep desilication of cokeꢀdeposited spent zeolite catalyst was
DOI: 10.1039/x0xx00000x
successfully developed to prepare hierarchical porous carbon monoliths (HPCMs). Such a strategy avoids
the use of hard or soft templates and carbon source, eliminates high temperature carbonization,
simultaneously, minimizes the emissions from processing spent catalysts. The resulting carbon exhibits a
controlled morphology such as threeꢀdimensional network, hollow sphere or nanosheets, a high degree of
graphitization and multiꢀlevel porous structure. Its mesopore (2ꢀ50 nm) surface area can reach 522 m2/g
and both mesopore and macropore (50ꢀ350 nm) volumes are more than 1.0 cm3/g. Such hierarchical
porous carbon was found to be a superior support for minimizing the nanoparticle size and enhancing the
synergism of FeꢀK catalyst for promoting CO2 hydrogenation. Using such catalyst results in increased the
conversion of carbon dioxide and enhanced selectivity of high value olefins (C2ꢀ4=) and longꢀchain
hydrocarbons (C5+).
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formation of coke with high degree of graphitization, which
could cause the catalyst deactivation.17ꢀ19 With the rapid
1 Introduction
Porous carbon materials can offer superior physical and
chemical properties, such as thermal conductivity, chemical
stability, electric conductivity and low density, leading to their
extensive use in batteries, supercapacitors, gas storage and as
supports for many important catalytic processes.1ꢀ4
Conventional carbon materials, such as activated carbon (AC),
are synthesized by carbonization and chemical (e.g. KOH5)
development of the chemical industry, large amounts of spent
zeolite catalysts are produced every year. However, most of
them are disposed of in landfills, which could lead to a serious
environmental problem and
materials.20
a large waste of valuable
Herein, an efficient and low cost strategy involving oneꢀstep
desilication of cokeꢀdeposited spent zeolite catalyst was
successfully developed to prepare hierarchical porous carbon
monoliths (HPCMs). Such strategy avoids the use of hard or
soft template and carbon source, eliminates high temperature
carbonization under inert atmosphere, and simultaneously,
decreases the emission of spent zeolite catalyst. The resulting
hierarchical carbon has been found to be a superior support of
FeK for minimizing the nanoparticle size and enhancing the Feꢀ
K synergism for promoting catalytic CO2 hydrogenation
reaction, especially for increased conversion of carbon dioxide
and enhanced selectivity of high value olefins (C2ꢀ4=) and longꢀ
activation of organic precursors, such as coal, wood, fruit shell,
7
and polymers.6,
These carbon materials normally have
micropores with high surface area. However, the narrow
channels limit the diffusion of molecules to access the active
site in the micropores. Recently, hierarchical porous carbon
materials have been synthesized using (a) hard templates8ꢀ10
through impregnation, carbonization, and template removal, or
(b) soft templates11ꢀ13 through condensation and carbonization.
These methods overcome the limitation of micropores but
suffer from complicated procedures and high costs. Therefore,
finding an efficient and low cost strategy to synthesize
hierarchical porous carbon is of great importance.14
+
chain hydrocarbons (C5 ).
ZSMꢀ5 type zeolites offer a strong and tunable acidity,
excellent shape selectivity and good hydrothermal stability,
leading to their widely use in petrochemical fields.15, 16 In the
catalytic process, such as methanol to propylene (MTP)
reaction, the acid sites on the outer surface can lead to the
2 Experimental
2.1 Synthesis of hierarchical porous carbon monoliths
(HPCMs)
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DOI: 10.1039/C5RA26009D
In this work, we selected three kinds of conventional highꢀ Micromeritics, USA) with two lowꢀpressure stations plus one
silica ZSMꢀ5 shaped catalyst, which were denoted as CATꢀ1, highꢀpressure station and a maximum pressure of 33,000 psia.
CATꢀ2 and CATꢀ3, respectively. The MTP reaction was
Xꢀray photoelectron spectroscopy (XPS) was conducted on
o
performed at 500 C in a fixedꢀbed reactor under atmospheric an ESCALAB 250 (Thermo VG Corporation) using Mg Kα
pressure. The WHSV for methanol was 3.0 hꢀ1 with a radiation (1253.6 eV, 15 kV, 10 mA, 150 W). The recorded
MeOH/H2O molar ratio of 1: 1. After fully deactivated in the spectra were fitted by a least square procedure to a product of
MTP reaction, the three kind of spent catalysts were selected as Gaussian–Lorentzian functions. The concentration of each
carbon source. The zeolite was removed using a mixture of element was calculated from the area of the corresponding peak.
hydrofluoric acid (10% in water). After 24 h, the obtained Raman spectra were collected using a Nicolet Almega XR
monolithic carbon was washed with water several times and Raman system with a 532 nm excitation laser from Thermo
dried overnight at 100 oC. The monolithic carbons obtained Fisher Scientific Inc.
from CATꢀ1, CATꢀ2 and CATꢀ3 was denoted as HPCMsꢀ1,
HPCMꢀ2 and HPCMsꢀ3, respectively.
H2ꢀTPR measurements were carried out with ChemBET
Pulsar TPR/TPD equipment (Quantachrome, USA) to analyse
the reducibility of the calcined catalysts. Prior to the reduction,
the calcined sample (0.10g) was placed in a quartz tube in the
2.2 Synthesis of HPCMs supported catalysts
The samples of commercial activated carbon (AC) and interior of a controlled oven. The sample was flushed with high
HPCMsꢀ1 were used as the support materials. The Feꢀbased purity argon at 300 oC for 8 h to remove water and other
catalyst was prepared by the incipient wetness impregnation contaminants then cooled down to room temperature. A gas
method using ethanol aqueous solutions (95 wt%) of Iron(III) mixture containing 5 vol% H2 in Ar was passed through the
acetylacetonate (Fe(acac)3) and potassium nitrate (KNO3). The sample at a total flow rate of 30 ml minꢀ1 with a heating rate at
o
o
o
catalyst was obtained after drying at 100 C overnight followed 10 C minꢀ1 up to 900 C. A cooling trap was placed between
o
by calcination in N2 at 500 C for 3 h to decompose iron and the sample and the detector for removal of released water
potassium precursors, for which the heating rate was 2 oC minꢀ1. formed during the reduction process.
The real Fe and K loading on the HPCMsꢀ1 are 11.4 and 5.7
2.4 Catalytic testing
wt %, respectively, as measured by energy dispersive Xꢀray
(Fig. S1).
The catalytic hydrogenation of carbon dioxide was carried
out in a pressurized fixedꢀbed flow reactor where a weighted 1
g catalyst was pretreated by reduction with pure H2 at 500 C
2.3 Characterization
o
Powder Xꢀray diffraction (XRD) patterns were recorded on a overnight. After the reduction, the feed gas was changed to the
Rigaku Smartlab diffract meter using nickelꢀfiltered CuKα Xꢀ mixture of carbon dioxide and hydrogen under the reaction
ray source at a scanning rate of 0.02o over the range between 5° conditions of n (H2)/n (CO2) =3 (molar ratio); P=3 MPa; T=400
and 80°. The crystallite phases were identified by comparing oC and the space velocity was 3600 mlgꢀ1hꢀ1.
the diffraction patterns with the data of the Joint Committee on
Powder Standards (JCPDS).
The products were analyzed onꢀline by a gas chromatograph
(FULI GC 97). Carbon monoxide, carbon dioxide and methane
Transmission electron microscopy (TEM) and high were analyzed on a carbon molecular sieve column with a
resolution transmission electron microscopy (HRTEM) images thermal conductivity detector (TCD) while methane and C2ꢀC8
were taken on a JEMꢀ2100F instrument (JEOL Company) with hydrocarbons were analyzed with a flame ionization detector
an acceleration voltage of 200 kV. The samples for TEM (FID) with a HayeSep Q column. Chromatograms were
analysis were prepared by dipping the copper grids into the correlated through methane and product selectivity was
ethanol solutions of the samples and drying at ambient determined based on carbon.
conditions.
Scanning electron microscopy (SEM) images were obtained
on a Hitachi Sꢀ5500 instrument with an acceleration voltage of
3 kV.
3 Results and discussion
3.1 Material synthesis and characterization
Thermo gravimetric analysis (TGA) was performed on an
SDT Q600 (TA Instruments, USA) in the temperature range of
25ꢀ800 °C under air or N2 at a heating rate of 10 °C minꢀ1.
The schematic of HPCMs synthesis is shown in Fig. 1a. For
ZSMꢀ5 zeolite, during the MTP reaction process, the carbon
species are mostly polycyclic aromatics. Due to the limitation
of micropores, carbon deposits often exist on the surface of the
zeolite, leading to severe diffusion restrictions and fast
deactivation of catalyst. Although the activity can be enhanced
by the calcination treatment, the catalyst activity and stability
are difficult to achieve the level of fresh catalyst. Thus, after
several regeneration treatments, the catalyst is no longer able to
meet industrial requirements, and this kind of catalyst is called
spent catalyst. We used spent catalyst as carbon source, after
o
Ar isotherms at ꢀ186 C were measured in a Quantachrome
autosorbꢀiQ2 gas adsorption analyzer. Prior to the measurement,
the samples were degassed in vacuum (p/p0
＜
10ꢀ7) at 300 oC for
10 h. The BrunauerꢀEmmettꢀTeller (BET) method was applied
to calculate the total surface area, while the microꢀmeso porous
size distribution was determined from Ar adsorption isotherm
by quenched solid density functional theory (QSDFT).
The mesoꢀ and macroꢀ porosity of the samples were
measured by a mercury porosimeter (AUTOPORE IV 9500,
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oneꢀstep zeolite removal using hydrofluoric acid, the HPCMs reticular (Fig. 3b), hollow (Fig. 3e) or sheet (Fig. 3h)
were obtained. Fig. 1b shows the image of fresh catalyst, which morphology will be obtained.
is cylinder with height of 2 mm and diameter of 1ꢀ10 mm. The
spent catalyst and HPCMs maintained the macroꢀmorphology
of the fresh catalyst, while the yield of HPCMs depends on the
coke content of spent catalyst. For spent CATꢀ1, the content of
o
coke with weight loss temperature greater than 400 C is 21
wt% (Fig. 2a). After zeolite movement, the yield of HPCMsꢀ1
is about 20 wt%, similar with the coke content of spent CATꢀ1.
The TG and DTG curves (Fig. 2b) show that the weight loss of
HPCMsꢀ1 under N2 at 800 oC was only 6 wt%, indicate the low
content of oxygen or volatile substances in HPCMꢀ1. The TG
curves of it under air confirm that the zeolite could removal
completely via hydrofluoric acid treatment.
Fig. 3 SEM (a, b, d, e, g, h) and TEM (c, f, i) images of CAT-1 (a), CAT-2 (d), CAT-3
(g) and HPCMs-1 (b, c), HPCMs-2 (e, f), HPCMs-3 (h, i).
Fig. 1 (a) Schematic of the HPCMs synthesis; image of fresh catalyst (b), spent
catalyst (c) and HPCMs (d)
Fig. 4 Ar adsorption and desorption isotherms at -186 oC (a), micro-meso pore
size distribution (b), Hg intrusion curve (c) and macro pore size distribution (d) of
HPCMs-1. The micro-meso porous size distribution was determined from Ar
adsorption isotherm by quenched solid density functional theory (QSDFT), and
the macroporous distribution was determined from Hg intrusion curve.
To determine the pore structure of HPCMs, Ar adsorption
and desorption isotherms and Hg intrusion curve were
measured. For HPCMsꢀ1, the Ar adsorption and desorption
Fig. 2 TG and DTG curves of (a) spent CAT-1 under air, (b) HPCMs-1 under air and
N2
isotherms show type
Ⅲ
/
Ⅳ
(macropore/mesopore)
characteristies (Fig. 4a). The increase in adsorption amount at
p/p0 (0.6ꢀ0.9) indicates the existence of mesopores, from which
calculated mesoporous (2ꢀ50 nm) volume is 0.53 cm3gꢀ1 (Table
1). The further Ar uptake at high p/p0 (0.9ꢀ1.0) demonstrates
the existence of macropores. To exactly determine the
macroporous structure of HPCMsꢀ1, Hg intrusion curve was
Fig. 3 shows the SEM and TEM images of the fresh catalyst
and HPCMs. Due to the coke often deposit on the surface of
ZSMꢀ5, after zeolite remove treatment, the morphology of
HPCMs will reverse copy the morphology of zeolite. For
example, if the morphology of zeolite is aggregate (Fig. 3a),
sphere (Fig. 3d) or rectangle (Fig. 3g), the HPCMs with
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DOI: 10.1039/C5RA26009D
measured (Fig. 4c), from which calculated macroporous (50ꢀ
350 nm) volume was 1.39 cm3gꢀ1. Fig. 4b and 4d show the
Table 1 Textural properties of the samples
[a]
[b]
[a]
[a]
[a]
[c]
Sample
Code
Smicro
SBET
Vmicro
Vmeso
Vmacro
Vpore
[m2g-1]
[m2g-1]
218
[cm3g-1]
[cm3g-1]
0.53(0.51d)
1.01
[cm3g-1]
0.94(1.39d)
1.07
[cm3g-1]
1.47
HPCMsꢀ1
HPCMsꢀ2
HPCMsꢀ3
HPCMsꢀ1ꢀ650
HPCMsꢀ1ꢀ750
HPCMsꢀ1ꢀ850
0
0
0
47
479
481
0
0
0
0.02
0.16
0.18
557
253
301
724
2.08
1.19
1.37
1.70
0.59
0.45
0.60
0.72
0.60
0.90
0.94
0.87
941
1.77
[a] QSDFT method, micropore (d<2 nm), mesopore (2 nm<d<50 nm) and macropore (d>50 nm) [b] BET method, [c] p/p0=0.99, [d] measured from Hg
intrusion, mesopore (24 nm<d<50 nm) and macropore (50 nm<d<350 nm)
microꢀmeso pore size distribution determined from Ar
The effect of KOH activation was also estimated. Ar
o
adsorption isotherm and the macropore distribution was adsorption and desorption isotherms at ꢀ186 C and pore size
determined from Hg intrusion curve, respectively. In addition, distributions of HPCMsꢀ1 after KOH activation are shown in
the pore structure of HPCMsꢀ2 and HPCMsꢀ3 were also Fig. 6a and 6b. With the rising temperature from 650 to 850 oC,
determined by Ar adsorptionꢀdesorption technique, (Fig. 5) the adsorption isotherms change from type
indicate all of the three HPCMs were mesoꢀmacro porous type (micropore/macropore/mesopore). Compared
materials without micropores.
Ⅲ/Ⅳ to combined
Ⅰ / Ⅲ / Ⅳ
with HPCMꢀ1, the BET surface area of HPCMsꢀ1ꢀ850
increased from 218 m2gꢀ1 to 941 m2gꢀ1, mainly of micropores
area growth. The micropore volume was also increased from 0
to 0.18 cm3gꢀ1. That because during the KOH activation, gases
such as CO2 and CO were generated, resulting in the formation
of micropores,21 meanwhile the mesopore and macropore were
still retained after KOH activation, and finally obtained microꢀ
mesoꢀmacro porous carbon monoliths as shown in Fig. 6b.
To determine the chemical structure of HPCMsꢀ1, XRD
pattern, Raman spectrum and XPS spectra were measured.
Before the removal of zeolite, the five characteristic diffraction
peaks of MFI topology at 7.8o, 8.8o, 23.0o, 23,9o, and 24.4o
clearly indicate the phase of ZSMꢀ5 (Fig. S2, JCPDS: 44ꢀ0003).
After remove zeolite, Fig. 7a shows the typical XRD patterns of
HPCMsꢀ1, the diffraction peaks of MFI topology disappear.
The broad XRD peak at 2ꢀTheta value of 24.5o was attributed to
the (002) reflection of the graphiticꢀtype lattice and the
corresponding interlayer spacing (0.36 nm) is slightly larger
than that of natural graphite (0.34 nm), which represents wellꢀ
developed graphitization.22, 23 The interlayer spacing could also
be measured from HRTEM image (Fig. 7a inset, Fig. S3),
which in agreement with the XRD result. The weak XRD peak
at 2ꢀTheta of 43.5o was attributed to the (101) reflection of
carbon structure.
o
Fig. 5 Ar adsorption and desorption isotherms at -186 C (a, c) and micro-meso
pore size distribution (b, d) of HPCMs-2 (a, b) and HPCMs-3 (c, d).
The Raman spectrum of HPCMsꢀ1 is shown in Fig. 7b. The
peak positions of the D and G bands are 1340 and 1587 cmꢀ1,
respectively. The D band is a common feature of disordered
carbons, while the G band is related to a graphitic carbon phase
with an SP2 electronic configuration.24 The radio of these two
bands (ID/IG) is 0.93:1, reflecting the partial graphitization of
the carbons in the HPCMs. The XPS spectrum of HPCMsꢀ1 is
shown in Fig. 7c. According to the XPS data, atomic
percentages of C (96.0 at%) and O (4.0 at%) can be determined.
The highꢀresolution C1S XPS spectrum showed a dominant
Fig. 6 Ar adsorption and desorption isotherms at -186 oC (a) and micro-meso
pore size distributions (b) of HPCMs-1 after KOH activation at 650, 750 and 850
oC for 3 h, respectively, KOH/HPMS-1=2:1 (weight ratio). The micro-meso pore
size distribution was determined from Ar adsorption isotherm by quenched solid
density functional theory (QSDFT).
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peak at 284.5 eV and two small peaks at 285.9 and 288.4 eV
The reduction behavior of catalysts was studied by H2ꢀTPR.
(Fig. 7d). The peak at 284.5 eV corresponds to the SP2ꢀ As shown in Fig. 8f, for the FeꢀK supported on the AC, the
hybridized graphitic carbon, while the peaks at 285.9 and 288.4 reduction temperature of metal oxide is lower than the monoꢀ
eV are attributed to CꢀOH and C=O configurations, metal loading samples. That is because the FeꢀK catalyst has a
respectively.25
higher metal dispersion, which has been proved by TEM
images and XRD patterns. Thus, the catalyst FeꢀK/HPCMs has
the lowest reduction temperature, this result suggests that the
catalyst FeꢀK/HPCMs had the highest degree of reduction after
reduction with pure H2 at 500 oC overnight.
Fig. 7 XRD pattern (a), Raman spectrum (b), XPS survey (c) and high-resolution
C1s XPS spectra (d) of HPCMs-1 (inset a: HRTEM image of HPCMs-1. inset c: chart
showing the percentages of carbon and oxygen according to XPS data)
3.2 HPMCs as the support of Fe-based catalyst for the
hydrogenation of carbon dioxide
Fig. 8a and 8bꢀd show TEM images of FeꢀK/AC and Feꢀ
K/HPCMsꢀ1, for the commercial activated carbon (AC) as
support, the metal oxide particles are of 17 nm mean size,
whereas using HPMCsꢀ1 as support, the mean size of metal
oxide particles decrease to about 9 nm. The lattice spaces are
measured to be 2.5 and 3.0 Å (Fig. 8d), which matches the
values of the dꢀspacing of Fe3O4 (311) and Fe3O4 (220),
respectively (JCPDS: 65ꢀ3107). Fig. S4 shows carbon (yellow),
iron (red) and potassium (green) element mapping images of
FeꢀK/AC (a, b, c, d) and 15Fe10K/HPCMsꢀ1 (e, f, g, h),
respectively. Compared with FeꢀK/AC, the iron and potassium
in the sample of HPMCsꢀ1 exhibit more uniform distribution,
which is conducive to enhancing the promotion and improves
the activity of the catalyst.
The decrease of particle size of metal oxide supported on the
HPMCsꢀ1 was also demonstrated by XRD patterns in Fig. 8e.
For the fresh catalysts, the XRD patterns exhibited the
characteristic diffraction peaks of Fe3O4 (JCPDS: 65ꢀ3107) at
30.1o, 35.5o, 43.2o, 53.5o, 56.9o and 62.6o. The Fe/AC shows a
sharp (311) peak, indicating the large particle size of Fe3O4.
When the potassium was introduced in the catalyst, the peaks of
Fe3O4 became broader, indicate the introduction of potassium is
interaction to the enhancement of iron disperse, which is
attributed to the interaction of iron and potassium. The wide
diffraction peaks of FeꢀK/HPCMsꢀ1 suggest that Fe3O4 particle
size is much smaller than on sample FeꢀK/AC, which is
consistent with the TEM and element mapping results.
Fig. 8 TEM (a, b, c) and HRTEM (d) images of Fe-K/AC (a) and Fe-K/HPCMs-1 (b, c,
d), respectively; (e) XRD patterns of Fe/AC (e-1), Fe-K/AC (e-2) and Fe-K/HPCMs-
1 (e-3); (f) H2 TPR profiles of Fe/AC (f-1), K/AC (f-2), Fe-K/AC (f-3) and Fe-K/
HPCMs-1 (f-4). The insets in (a) and (b) show the particle size distributions of
metal oxide based on measurements of approximately 100 nanoparticles by TEM.
Table 2 shows the catalytic performances of the carbon
supported Feꢀbased catalysts for CO2 hydrogenation. For monoꢀ
metal Fe catalyst (Fe/AC), the conversion of CO2 was very low
(5.6 %) because of the weak adsorption of iron species to
carbon oxide. For monoꢀmetal
K catalyst (K/AC), the
conversion of CO2 was increase to 15.6, however, due to its
weak activation ability to hydrogen, the selectivity of CO is
very high (93.6%), mainly occurred reversedꢀwaterꢀgasꢀshift
reaction. When the potassium was introduced in the ironꢀbased
catalyst (FeꢀK/AC), the synergistic effect of iron and potassium
simultaneously enhances the activation of hydrogen and
adsorption of carbon dioxide,26, 27 increasing the conversion of
carbon dioxide to 27.0%. However, because of the uneven
distribution of iron and potassium, the selectivity of
hydrocarbon has not been improved. As expected, the use of
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HPCMsꢀ1 as the support significantly increased the conversion b EMS Energy Institute, PSUꢀDUT Joint Center for Energy Research,
of CO2 to 33.4%, decreased the selectivity of CO to 38.9% as Department of Energy & Mineral Engineering, and Department of
=
+
well as increased the selectivity of high value C2ꢀ4 and C5
Chemical Engineering Pennsylvania State University, University Park,
hydrocarbons to 18.0% and 18.1%, respectively. Pennsylvania 16802, United States. Fax: 814ꢀ865ꢀ3573; Tel: 814ꢀ863ꢀ
Characterization and catalytic performance results show that 4466; Eꢀmail: csong@psu.edu.
the HPCMs is a superior support of FeK for minimizing the †Electronic Supplementary Information (ESI) available: [HRTEM image
nanoparticle size and enhancing the FeꢀK interaction for of HPCMsꢀ1, Raman spectra of HPCMsꢀ1 after thermal treatment at
promoting catalytic performance of CO2 hydrogenation.
different temperatures under N2].
Table 2 CO2 conversion and selectivity of Fe/AC, K/AC, FeꢀK/AC and
FeꢀK/ HPCMsꢀ1, respectively. Reaction conditions: n (H2)/n (CO2) =3
1. C. Liang, Z. Li and S. Dai, Angew. Chem. Int. Ed, 2008, 47, 3696ꢀ
3717.
o
(molar ratio); P=3 MPa; T=400 C and the space velocity was 3600
mlgꢀ1hꢀ1, time on stream 5h.
2. S. Wang, C. Han, J. Wang, J. Deng, M. Zhu, J. Yao, H. Li and Y.
Wang, Chem. Mater., 2014, 26, 6872ꢀ6877.
CO2
Conv.
(%)
Selectivity (%)
3. B. Zhu, K. Li, J. Liu, H. Liu, C. Sun, C. E. Snape and Z. Guo, J.
Catalyst
=
0
+
Mater. Chem. A, 2014, 2, 5481ꢀ5489.
CO CH4 C2ꢀ4
C2ꢀ4
C5
4. M. Park, J. Ryu, Y. Kim and J. Cho, Energy Environ. Sci., 2014,
3727ꢀ3735.
7,
Fe/AC
K/AC
FeꢀK/AC
FeꢀK/
5.6
15.6
27.0
66.3 24.6
93.6 4.6
92.5 4.2
0.4
0.1
0.6
8.7
1.7
2.4
0
0
0.3
5. M. Li, C. Liu, H. Cao, H. Zhao, Y. Zhang and Z. Fan, J. Mater. Chem.
A, 2014, , 14844.
2
6. L. Zhou, H. Cao, S. Zhu, L. Hou and C. Yuan, Green Chem., 2015,
17, 2373ꢀ2382.
33.4
38.9 13.5
18.0
11.5
18.1
HPCMsꢀ1
7. L. Zhu, Q. Gao, Y. Tan, W. Tian, J. Xu, K. Yang and C. Yang,
Microporous and Mesoporous Mater., 2015, 210, 1ꢀ9.
8. W. Nickel, M. Oschatz, M. v. d. Lehr, M. Leistner, G.ꢀP. Hao, P.
Adelhelm, P. Müller, B. M. Smarsly and S. Kaskel, J. Mater. Chem.
4 Conclusions
In this work, hierarchical porous carbon monoliths have been
successfully synthesized by an efficient and low cost strategy
from cokeꢀdeposited spent zeolite catalyst. The resulting carbon
A, 2014,
2, 12703.
9. P. Strubel, S. Thieme, T. Biemelt, A. Helmer, M. Oschatz, J.
Brückner, H. Althues and S. Kaskel, Adv. Funct. Mater., 2015, 25
,
exhibits
a
controlled morphology,
a
high degree of
287ꢀ297.
graphitization and a mesoꢀmacro porous structure. Such
hierarchical porous carbon was found to be a superior support
of FeK for minimizing the nanoparticle size and enhancing the
FeꢀK interaction for promoting catalytic performance of CO2
hydrogenation.
10. L. Song, L. Li, X. Gao, J. Zhao, T. Lu and Z. Liu, J. Mater. Chem. A,
2015, , 6862ꢀ6872.
3
11. S. D. C. Liang, J. Am. Chem. Soc., 2006, 128, 5316ꢀ5317.
12. C. Liang, K. Hong, G. A. Guiochon, J. W. Mays and S. Dai, Angew.
Chem. Int. Ed, 2004, 43, 5785ꢀ5789.
The present strategy in this work can be used for preparing a
wide range of synthetic hierarchical porous carbon materials,
because the spent catalyst with specific channels and
morphologies can be selected to obtain the carbon material we
need. For example, some spent zeolite catalysts with a large
microꢀpore size (e.g. Y or Beta) may be used to synthesize
microporous carbon material with high surface area.
13. S. Tanaka, N. Nishiyama, Y. Egashira and K. Ueyama, Chem.
Commun., 2005, 2125ꢀ2127.
14. A. D. Roberts, S. Wang, X. Li and H. Zhang, J. Mater. Chem. A,
2014, 2, 17787ꢀ17796.
15. Z. Qin, L. Lakiss, L. Tosheva, J.ꢀP. Gilson, A. Vicente, C. Fernandez
and V. Valtchev, Adv. Funct. Mater., 2014, 24, 257ꢀ264.
16. S. Mitchell, N. L. Michels, K. Kunze and J. PerezꢀRamirez, Nature
Chem., 2012,
4, 825ꢀ831.
Acknowledgements
17. S. Müller, Y. Liu, M. Vishnuvarthan, X. Sun, A. C. van Veen, G. L.
Haller, M. SanchezꢀSanchez and J. A. Lercher, J. Catal., 2015, 325
,
The authors thank the financial support from the National
Natural Science Foundation of China (21306018, 21503029,
21503027) and the Fundamental Research Funds for the Central
Universities (DUT15ZD236, DUT15RC(3)027).
48ꢀ59.
18. F. Schmidt, C. Hoffmann, F. Giordanino, S. Bordiga, P. Simon, W.
CarrilloꢀCabrera and S. Kaskel, J. Catal., 2013, 307, 238ꢀ245.
19. L. R. Aramburo, S. Teketel, S. Svelle, S. R. Bare, B. Arstad, H. W.
Zandbergen, U. Olsbye, F. M. F. de Groot and B. M. Weckhuysen, J.
Catal., 2013, 307, 185ꢀ193.
Notes and references
20. Q. Zhang, S. Hu, L. Zhang, Z. Wu, Y. Gong and T. Dou, Green
Chem., 2014, 16, 77ꢀ81.
a State Key Laboratory of Fine Chemicals, PSUꢀDUT Joint Center for
Energy Research, School of Chemical Engineering, Dalian University of
Technology, Dalian 116024, P. R. China. Fax: +86ꢀ0411ꢀ84986134; Tel:
+86ꢀ0411ꢀ84986133, +86ꢀ0411ꢀ84986134; Eꢀmail: guoxw@dlut.edu.cn
21. T. Mitome, Y. Iwai, Y. Uchida, Y. Egashira, M. Matsuura, K.
Maekawa and N. Nishiyama, J. Mater. Chem. A, 2014,
22. H. Peng, G. Ma, K. Sun, J. Mu and Z. Lei, J. Mater. Chem. A, 2014,
, 17297ꢀ17301.
2, 10104.
2
6 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 2012

Page 7 of 8
Journal Name
RSC Advances
View ArticAle ROnTliInCeLE
DOI: 10.1039/C5RA26009D
23. S. Tao, Y. Wang, D. Shi, Y. An, J. Qiu, Y. Zhao, Y. Cao and X.
Zhang, J. Mater. Chem. A, 2014, , 12785.
24. X. Meng, H. Cui, J. Dong, J. Zheng, Y. Zhu, Z. Wang, J. Zhang, S.
Jia, J. Zhao and Z. Zhu, J. Mater. Chem. A, 2013, , 9469.
25. P. Chen, L.ꢀK. Wang, G. Wang, M.ꢀR. Gao, J. Ge, W.ꢀJ. Yuan, Y.ꢀH.
2
1
Shen, A.ꢀJ. Xie and S.ꢀH. Yu, Energy Environ. Sci., 2014,
4103.
7, 4095ꢀ
26. R. Satthawong, N. Koizumi, C. Song and P. Prasassarakich, J. CO2
Utilization, 2013, 3-4, 102ꢀ106.
27. C. Dai, A. Zhang, L. Li, K. Hou, F. Ding, J. Li, D. Mu, C. Song, M.
Liu and X. Guo, Chem. Mater., 2013, 25, 4197ꢀ4205.
This journal is © The Royal Society of Chemistry 2012
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A versatile strategy involving one-step desilication of coke-deposited spent zeolite catalyst was
successfully developed to prepare hierarchical porous carbon monoliths (HPCMs).