Boron and Nitrogen Doping in Graphene for the Catalysis of Acetylene Hydrochlorination

Article abstract of DOI:10.1021/acscatal.5b00199

Exploration of environmentally friendly catalysts is important for acetylene hydrochlorination because the traditional HgCl₂ catalyst is highly toxic and harmful to human health. Herein, boron and nitrogen heteroatoms dually doped on oxide graphene (B,N-G) catalyst were synthesized using a model calcination method and applied as a nonmetallic catalyst for acetylene hydrochlorination. The B,N-G catalyst shows acetylene conversion significantly higher (nearly 95%) than that of singly B- or N-doped graphenes and a little lower than that of Au and Hg catalyst. Density functional theory calculations and temperature-programmed desorption results indicate that the synthetic effect of B and N doping can promote HCl adsorption, which is the rate-determining step in acetylene hydrochlorination. The excellent catalytic efficiency and relatively low cost of B,N-G makes it a promising catalyst for acetylene hydrochlorination.

Full text of DOI:10.1021/acscatal.5b00199

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Article
Boron and nitrogen doping in graphene for
the catalysis of acetylene hydrochlorination
Bin Dai, Kun Chen, yang wang, Lihua Kang, and Mingyuan Zhu
ACS Catal., Just Accepted Manuscript • DOI: 10.1021/acscatal.5b00199 • Publication Date (Web): 15 Mar 2015
Downloaded from http://pubs.acs.org on March 17, 2015
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Boron and nitrogen doping in graphene for the catalysis of acetylene
hydrochlorination
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Bin Daia, b, Kun Chena, Yang Wanga, Lihua Kanga,b, Mingyuan Zhua, b
*
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aSchool of Chemistry and Chemical Engineering of Shihezi University, Shihezi,
Xinjiang, 832000, RP China.
bKey Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan,
Shihezi, Xinjiang, 832000, RP China.
*Corresponding author. Tel.: +86 9932057270; Fax: +86 9932057210.
E-mail address: zhuminyuan@shzu.edu.cn (M. Zhu)
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Abstract: Exploration of environmentalꢀfriendly catalysts is important for
acetylene hydrochlorination, due that the traditional HgCl2 catalyst is highly toxic and
harmful to human health. Herein，boron and nitrogen heteroatoms dual doped on
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oxide graphene (B, NꢀG) catalyst was synthesized using a model calcination method
and applied as a nonꢀmetallic catalyst for acetylene hydrochlorination. The B, NꢀG
catalyst shows acetylene conversion significantly higher (nearly 95%) than that of
singly Bꢀ or Nꢀdoped graphenes and a little lower than that of Au and Hg catalyst.
Density functional theory calculations and temperatureꢀprogrammed desorption
results indicate that the synthetic effect of B and N doping can promote HCl
adsorption, which is the rateꢀdetermining step in acetylene hydrochlorination. The
excellent catalytic efficiency and relatively low cost of B, NꢀG makes it a promising
catalyst for acetylene hydrochlorination.
Keywords: Nitrogen and boron doping; Graphene; Metalꢀfree catalyst; Acetylene
hydrochlorination; HCl adsorption
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1. Introduction
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Polyvinylchloride (PVC) polymerization from vinyl chloride monomer (VCM) is
one of the most widely used engineering plastics in various aspects of human life, and
is suitable for numerous manufacturing various products, such as water pipes and
fittings, electric wires, and plastic membranes. The domestic industrial production of
VCM in China is mainly through calcium carbide method (acetylene
hydrochlorination), and the reaction is catalyzed by carbonꢀsupported mercuric
chloride catalyst. However, the toxic mercuric chloride causes serious environmental
problems and harm to human health [1]. Therefore, the extended studies on
environmentalꢀfriendly catalysts have attracted increasing interest and are important
for the industrial application of acetylene hydrochlorination.
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Considerable catalytic activity has been achieved on some chloride of transition
metals, such as Au [2], Bi [3], and Pt [4], towards acetylene hydrochlorination.
Hutchings et al. [5, 6] found that Au/AC has the best activity among these transition
metals. Hutchings et al. also achieved an optimized catalytic activity when the catalyst
contains 1 wt.% Au, although the poor stability of an Au catalyst still could not meet
the criteria for industrial application [7ꢀ9]. As Au catalyst is expensive and scarce,
exploitation of lowꢀcost catalysts may be another development strategy for acetylene
hydrochlorination catalyst [10, 11].
Recently, several Nꢀdoped carbons materials have been applied as novel
heterogeneous catalysts for acetylene hydrochlorination. In our previous work [12],
we reported that the acetylene conversion on gꢀC3N4/AC catalyst is about 70% that of
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Au/AC catalyst. Wei et al. [13] similarly found that Nꢀdoped carbon nanotubes
(NꢀCNTs) enhances the formation of the covalent bond between C2H2 and NꢀCNTs,
and therefore promotes the catalytic activity for acetylene hydrochlorination. Recently,
Bao et al. [14] reported that a nanocomposite of Nꢀdoped carbon derived from silicon
carbide (SiC@NꢀC) directly activates acetylene hydrochlorination, has stable activity
during acetylene conversion, which can reach 80%, and has vinyl chloride selectivity
over 98% at 200 °C. Although Nꢀdoped carbon has considerable catalytic activity, its
acetylene conversion is still lower than that of Au/AC and Hg/AC catalysts.
In the last few years, Nꢀdoped graphene materials gained substantial attention as
catalyst for oxygen reduction reactions (ORR) [15ꢀ19]. Studies have reported that by
sequentially incorporating N and B into selected sites of the graphene domain
enhances the synergistic coupling effect that facilitates the catalytic ORR. In this
study, N, B dual doped graphene was prepared through a twoꢀstep method, and the
obtained catalyst showed a catalytic activity for acetylene hydrochlorination that is
only a little lower than that of Au catalyst.
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2. Experimental
2.1 Chemicals and reagents
Graphite powder (99.85%, J&K Chemical), Boric Acid (H3BO3, 99.5%, J&K
Chemical), C2H2(gas, 98%), HCl (gas, ≥99%) were used in the present study.
2.2 Catalyst preparation
Graphene oxide (GO) was prepared according to classical Hummers method
[20ꢀ22]. Graphite powder (5 g) was pretreated by the solution of concentrated H2SO4
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(30 mL), K2S2O8 (2.5 g), and P2O5 (2.5 g). The preꢀoxidized graphite powder was
added into H2SO4 (120 mL) solution and stirred for 10 min under ice bath. Then,
KMnO4 (18 g) was added gradually under stirring and the temperature of the mixture
was kept to be below ~15 °C by ice cooling, the mixture was stirred at 35 °C for 2 h.
After diluted with deionized water (250 mL), the mixture was stirred for 2 h
successively. The reaction was cooled to room temperature and poured onto 400 mL
of cold deionized water. Successively, 20 mL of fresh 30% H2O2 was added, until
observation of the mixture color changed into brilliant yellow along with bubbling,
which indicating the complete oxidation of graphite. The resultant solution was
centrifuged to obtain the product. The product was washed by 10% HCl aqueous
solution and deionized water. The GO powder was collected by lyophilization for
further characterizations and experiments.
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To prepare the Bꢀdoped graphene (BꢀG), GO powder was mixed with excess boric
acid in an Al2O3 combustion boat and was heated to 900 °C under flowing Ar for 5 h
with a heating rate of 5 °C/min. After annealing, the furnace was cooled to room
temperature under the flowing Ar, and then the residual B2O3 was removed by
washing with the boiling water. Nꢀdoped graphene (NꢀG) was synthesized by
annealing GO powder under 20% NH3/Ar at 900 °C for 5 h. A twoꢀstep B, N
coꢀdoping of graphene was achieved by annealing the preꢀsynthesized BꢀG
intermediate under 20% NH3/Ar at 900°C for 5 h.
2.3 Catalyst characterization
Physical characterization of the sample was performed using a transmission
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electron microscope (TEM, JEOL, JEM 2010 operating at 200 kV) forits
morphological features. Xꢀray photoelectron spectroscopy (XPS) measurements were
performed using an Axis Ultra spectrometer with a monochromatized Al Kα Xꢀray as
the excitation source (225W). Temperatureꢀprogrammed desorption (TPD) was
conducted using a Micromeritic ASAP 2720 instrument over a temperature ramp of
50 ºC to 600ºC, ramp rate of 10 ºC/min, and flow rate of 40 mL/min under nitrogen
atmosphere. Thermo gravimetric analysis (TGA) was conducted with TGA/DTA
system (SDT Q600, America) at room temperature to 900 ºC with air flow of 10
mL/min. The Raman spectra were obtained using a Raman spectrometer (Renishaw)
with 514.3 nm Ar laser.
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2.4 Catalytic performance evaluation
The catalyst performance evaluation was performed in a fixed bed microreactor (i.d.
of 10mm). Before initiating the reaction, the reactor was purged with nitrogen to
remove water and air in the reaction system. Hydrogen chloride gas was passed
through the pipeline at a flow rate of 20 mL/min to activate the catalyst (0.5 g) until
the microreactor was heated to 150°C. Afterward, acetylene and hydrogen chloride
were fed through the microreactor, producing a gas hourly space velocity (GHSV,
C2H2) of 36 hꢀ1. The exit gas mixture was passed through an absorption bottle
containing clean water, and injected into a Shimadzu GCꢀ2014C chromatograph for
analysis. The conversion of acetylene (XA) and the selectivity to VCM (SVC) as the
criteria of catalytic performance were defined as following equations [9], respectively.
ꢀ
ꢃꢀ
ꢁꢂ
ꢀ
ꢁꢂ
ꢁ
XA=
× 100%
(1)
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ꢀ
ꢄꢅ
SVC=
× 100%
(2)
ꢆꢃꢀ
ꢁ
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In the equations, ϕA0 is defined as the volume fraction of acetylene in the raw gas
and ϕA is defined as the volume fraction of remaining acetylene in the product gas,
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ϕ
VC is the volume fraction of vinyl chloride in product gas.
The turn over frequency (TOF) of acetylene as the criteria of catalytic performance
was calculated using the following equation.
ꢇ
ꢈ
ꢊ
ꢉ
ꢉ
TOF =
(3)
ꢇ
×ꢌ
ꢋ
2.5 Computational details
DFT calculations were performed using the hybrid B3LYP [23, 24] function, as
implemented in the Gaussian 09 computer program package [25]. The standard
6ꢀ311G ++** basis set was used for H, C, N, B and Cl atoms. Atomic charges were
calculated using the Mulliken type. The geometries of all structures involved in the
mechanism were optimized fully without any restrictions. The frequencies of all
geometries were calculated at the same level to identify the nature of the stationary
points and obtain the zeroꢀpointꢀenergy (ZPE) corrections. All stationary points were
characterized as minima (no imaginary frequencies) via Hessian calculation. An
important reference point for this calculation is the adsorption energy for HCl on NꢀG
and B, NꢀG. In this paper, we used the following definitions for adsorption energy.
When HCl is adsorbed on graphene (NꢀG and B, NꢀG), the adsorption energy is
calculated as:
E= E (system) –E (G) –E (HCl)
(4)
E (system) is the total energy of adsorption system; E (G) denotes the energy of NꢀG or B,
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NꢀG; E (HCl) is the energy of HCl, respectively.
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3. Results and discussions
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Fig. 1aꢀc shows the TEM images that display the typical structures and
morphologies of GO, NꢀG, and B, NꢀG transparent sheets with wrinkled and
voileꢀlike features. Despite of the pristine GO with the substitution of several carbon
atoms with heteroatoms, the nanosheet morphology was preserved. Fig. 2a shows the
room temperature Raman spectra for pristine GO, NꢀG, and B, NꢀG at 514.3 nm
excitation. The IG/ID is a known parameter of carbon materials, which is important in
evaluating the degree of graphitization. The G band at 1597 cmꢀ1 originates from the
bond stretching of all sp2ꢀbonded pairs, and the D band at 1352 cmꢀ1 is associated with
the sp3 defect sites. The graphiteꢀinduced Gꢀband notably shows a sequential decrease
in intensity, which suggests that the increasing presence of N or B heteroatoms in the
target is, in fact, bringing about a noticeable change in the ordering degree of the
hexagonal lattice. These results are consistent with those of a previous report [26ꢀ28].
The XPS survey spectrum of the elemental compositions of GO, BꢀG, NꢀG, and B,
NꢀG shown in Fig. 2b, which presents a predominant C1s peak (284.5 eV) and an O1s
peak (532.0 eV). The detailed list showing the results of the quantitative evaluations
performed through XPS confirms the existence of elemental N and B in the different
graphene samples (Table1). Unlike undoped graphene, all the Nꢀdoped graphene
samples show a visible N1s peak (399.5eV). The N levels in NꢀG, and B, NꢀG, are
5.47%, and 10.96%, respectively. These results suggest nitrogen can be incorporated
inꢀsitu into the sp2 hybridized network in the presence of NH3. Similarly, the binding
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energy values coincide with the data from literature [26, 29]. The XPS results together
with that of Raman spectroscopy strongly confirmed that N and B atoms were
successfully introduced into the graphene framework through covalent bonds.
To gain more insight into molecular structure of N/Bꢀbonding configurations,
detailed scans for the N1s and B1s, including their deconvolutions from
highꢀresolution XPS, are shown in Fig. 2cꢀd. Compared with the N1s of NꢀG
(Supporting information, Figure S1), highꢀresolution N1s peaks of B, NꢀG
downꢀshifted to a lower binding energy. The lowest binding energy (398.0 eV) in the
N1s spectrum is related to NꢀB bonded groups, which means that first with B and then
to N can results boron nitride species. In addition, B, NꢀG have two split peaks in the
highꢀresolution XPS B1s spectrum, the main peak at around 188.9 eV is attributable
to BC3, indicating that B heteroatoms have been successfully incorporated into the
graphene lattice network. The BꢀN chemical bonds have also been observed in 190.9
eV [30, 31].
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Under the same reaction conditions, the catalytic activity of GO, BꢀG, NꢀG, and B,
NꢀG catalysts were evaluated using a fixed bed reactor, and the results are shown in
Fig.3a. The figure shows that the initial acetylene conversion has the following trend:
B, NꢀG > NꢀG > BꢀG > GO. Pristine GO showed negligible acetylene conversion
(12.07%), and the acetylene conversion of BꢀG is only 26.96%, indicating that the B
dopant has minimal effect on the catalytic activity on GO. However, NꢀG displays a
substantially higher catalytic activity, and its acetylene conversion reach 62.74%.
Numerous literatures have reported that Nꢀdoped carbon acts as a nonꢀprecious
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catalyst for acetylene hydrochlorination [12ꢀ14]. Li et al. reported that the acetylene
conversion of graphitic carbon nitride (gꢀC3N4/AC) was about 45% at a GHSV of 50
hꢀ1, and the catalytic performance of NꢀG for acetylene hydrochlorination is similar
with those reported in literature. Dualꢀdoped B, NꢀG catalyst interestingly exhibits an
acetylene conversion of 94.98%, indicating that the B atom improves the catalytic
activity of NꢀG for acetylene hydrochlorination. Supporting information, Figure S2,
exhibited excellent selectivity of the singly/doubly doped graphenes for vinyl chloride
monomers (at more than 98%) throughout the process, while pristine GO had a
slightly lower selectivity. To compare the capacity of chlorinating C2H2 into VCM, the
turn over frequency (TOF) value of metalꢀbased catalysts (including Au, Hg), as well
as the NꢀG and B, NꢀG metalꢀfree catalysts are illustrated in Fig. 3b. The TOFs of
NꢀG and B, NꢀG catalysts were 8.33 ×10ꢀ3 minꢀ1 and 3.32×10ꢀ2 minꢀ1, respectively.
TOF of SiC@NꢀC catalyst reported by Bao et al. was about 5.63×10ꢀ3 minꢀ1 [14], and
that of C3N4 material in our previous work was 1.42×10ꢀ2 minꢀ1 [12]. Those results
indicate that the acetylene hydrochlorination rate on B, NꢀG is somewhat higher than
the previous reported catalysts. From Fig. 3b, it can also be seen that the TOF of
Au/AC and Hg/AC are 5.38 minꢀ1 and 0.22 minꢀ1, respectively, being close to the
literature [8]. It can be concluded the catalytic performance of B, NꢀG is about 15% of
Hg/AC and 6‰ of Au/AC catalyst. The addition of the second heteroatoms has
minimal effect on the selectivity, but dramatically enhances the catalytic activity. Both
experimental and theoretical studies reveal that the carbon atoms bonded with N
species are the active sites, and the schematic illustration of acetylene
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hydrochlorination for B, NꢀG catalysts was shown in Fig. 4, more details of which
would be stated subsequently.
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The high catalytic activity of the doubly doped graphene layers in the acetylene
hydrochlorination can be ascribed to the following two reasons: First, B, NꢀG
provides more active sites compared with NꢀG because B, NꢀG has higher N content
than NꢀG according to the results shown in Table 1; and second, the presence of B
atom changes the electronic state of N atom (Supporting information, Figure S3) and
thus affects the adsorption of HCl on N active sites because the adsorption of chloride
molecule is the rateꢀdetermining step of the acetylene hydrochlorination process.
It is well known that GO is in abundance of oxygen atoms, in order to elucidate the
effect of oxygen containing group on the catalytic performance, we build some valid
models of GO, NꢀG, B, NꢀG with and without the presence of O atom, and the results
was listed in Table S1 and Figure S4. These models are based on a previous study
about oxygen reduction reaction on a heteroꢀdoped graphene [18, 26]. From the
aforementioned XPS analysis, three N species were considered and investigated
because these N species significantly differ in terms of their structures. Different from
traditional Hg and Au catalyst, carbon atom acts as the adsorbing site for C2H2, and
nitrogen atom provides the catalytic active site for HCl. Therefore, the carbon atoms
bonded with N species are the active sites. As shown in Table S1, the presence of
oxygen atom on NꢀG and B, NꢀG catalysts decrease the adsorption of HCl. As the
adsorption of HCl is the rate determining step of acetylene hydrochlorination, it can
be inferred that suggesting that no obvious promoting effect is present for oxygen
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containing group on graphene layer. DFT calculations were also carried out to gain
the fundamental understanding on the adsorption of acetylene (Supporting
information, Figure S5). Theoretically results demonstrated that Bꢀdoping hardly
enhanced the adsorption of acetylene, however, the various N species that interact
with HCl have extremely different functions. Different species of N in the catalytic
active sites for HCl adsorption (Eads) were identified in Fig. 3c. For NꢀG, a twoꢀfold
coordinated pyridinic N dopant at the edge of the cluster had a specific and dominant
HCl adsorption capability. However, no significant HCl adsorption capacity was
observed with pyrrolic N, which agrees with the results of previous studies [12]. For
dualꢀdoped B, NꢀG, a higher Eads value than those surveyed for NꢀG in both three
types N was observed, suggesting that the catalyst enhanced the acetylene
hydrochlorination reaction and thereby supports the aboveꢀdiscussed experimental
results. The previously identified inactive pyrrolic N atom can boost HCl adsorption
because of the coupling interaction between pyridinic N and B, which is shown by the
dramatically increasing adsorption energy. The transition of pyrrolic N group from
“inactive” into “active” after B incorporation can provide a better catalytic activity
compared with NꢀG for the acetylene hydrochlorination. This result highlights the
importance of B in the reaction. As for the graphitic N atom at the center of graphene
layers, the energy of HCl are minimal, the hydrogen chloride molecule is hardly
adsorbed at the active site of graphitic nitrogen. Furthermore, there are no obvious
promoting effect between graphitic N and B atom.
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adsorption and activation of HCl on different graphenes. The desorption temperature
in the TPD profiles reflects the binding strength of the adsorbed species with the
material surface, and the peak areas correspond to the amount of adsorbed species.
Fig.3d shows that the binding strength of HCl with various graphene materials
increases in the following order: GO < NꢀG < B, NꢀG. The desorption temperatures of
the highest peak were 196.8, 219.2, and 275.5 °C, respectively. In addition, GO has a
negligible HCl adsorption ability, implying that almost no catalytic active sites are
found on this catalyst. Compared with the original GO without doping, the
improvement of the adsorption performance of NꢀG highly depends on the
considerably stronger interaction between N and HCl, thus validating the capability of
N for directly activating HCl. A considerable HCl absorption occurred on B, NꢀG
because of additional N content and stronger adsorption of HCl in the presence of B
atoms, which explains the excellent acetylene conversion observed. These results
support our theoretical observation from DFT calculations of the HCl adsorption and
outstanding activity of the B, NꢀG.
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Fig. 5 evidently shows that the acetylene conversion of B, NꢀG decreased from
94.89% to 61.88% within 4 h, indicating its poor catalytic stability during acetylene
hydrochlorination. The decrease of activity was due to the severe deactivation of
catalyst. It was confirmed that the coke formation covered on the active sites was the
main reason for deactivation according to the TGA results as showed in Fig. 6. TGA
was used to evaluate the degree of carbon deposition on the surface of catalysts,
which based on previous reported calculation method [10]. In generally, there have
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two parts of mass loss within 100ꢀ500 °C; first, the burning of coke deposition on the
catalyst surface; second, the oxidation of carbon carrier in the atmosphere and then
escaping as CO2.. Therefore, the amount of carbon deposition should be equal to the
difference of the mass loss between the fresh and used catalysts in the temperature
range of 100ꢀ500 °C. The mass loss of the spent B, NꢀG is 5.0 wt.% higher than that
of the fresh B, NꢀG catalyst within the 100 °C to 500 °C. This result indicates that
coke deposition occurs on the B, NꢀG catalyst as the reaction proceeds. Therefore,
coke deposition may be the reason for the deactivation of B, NꢀG in acetylene
hydrochlorination. To reactivate the covered active sites, burning off the coke with
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hydrogen in 600 C was studied. After the first regeneration, the activity curve
implied initial acetylene conversion recover to 93% although the acetylene conversion
decreased rapidly as the reaction went on 60 min, which demonstrated well recovery
ability. The second regeneration was employed again to recover the activity of the
deactivated B, NꢀG catalyst. However, the initial acetylene conversion partially
recovers to 82%, which may be caused by the insufficient regeneration. Overall,
o
burning off the deactivated B, NꢀG catalyst with hydrogen in 600 C is an available
technique in recovering activity.
4. Conclusions
In summary, B, NꢀG catalyst was prepared and applied in acetylene
hydrochlorination. This catalyst a exhibited high activity for acetylene conversion,
reaching 94.87%, and is selective to vinyl chloride (above 98%) with GHSV (C2H2)
of 36 hꢀ1 and at 150 °C. The enhanced catalytic activity of B, NꢀG catalyst may be
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attributed to the improved HCl adsorption, which is proved by the DFT calculation
and TPD experiment. Therefore, B, NꢀG is a promising catalyst for acetylene
hydrochlorination because of its high catalytic efficiency and relatively low cost.
Acknowledgments
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This work was supported by the National Basic Research Program of China
(973Program, 2012CB720302), the Program for Changjiang Scholars and Innovative
Research Teams in University (PCSIRT, IRT1161), and National Natural Science
Funds of China(NSFC, 21366027).
References
[1] Li, X.; Zhu, M.; Dai, B. Appl. Catal. B-Environ. 2013, 142, 234ꢀ240.
[2] Hutchings, G.J.; Haruta, M. Appl. Catal. A- Gen. 2005, 291, 2ꢀ5.
[3] Smith, D.; Walsh, P.; Slager, T. J. Catal. 1968, 11, 113ꢀ130.
[4] Mitchenko, S.A.; Krasnyakova, T.V.; Mitchenko, R.S.; Korduban, A.N. J. Mol.
Catal. A- Chem. 2007, 275,101ꢀ108.
[5] Nkosi, B.; Adams, M.D.; Coville, N.J.; Hutchings,G.J. J. Catal. 1991, 128,
378ꢀ386.
[6] Hutchings, G.J. Catal. Today 2002, 72, 11ꢀ17.
[7] Nkosi, B.; Coville, N.J.; Hutchings, G.J.; Adams, M.D.; Friedl, J.; Wagner, F.E. J.
Catal. 1991, 128, 366ꢀ377.
[8] Conte, M.; Carley, A.F.; Heirene, C.; Willock, D.J.; Johnston, P.; Herzing, A.A.;
Kiely, C.J.; Hutchings, G.J. J. Catal. 2007, 250, 231ꢀ239.
[9] Zhang, H.; Dai, B.; Wang, X.; Xu, L.; Zhu, M. J. Ind. Eng. Chem. 2012, 18, 49ꢀ54.
15
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1
2
3
4
5
6
[10] Zhang, H.; Dai, B.; Wang, X.; Li, W.; Han, Y.; Gu, J.; Zhang, J. Green Chem.
2013, 15, 829ꢀ836.
7
8
9
[11] Huang, C.; Zhu, M.; Kang, L.; Li, X.; Dai, B. Chem. Eng. J. 2014, 242, 69ꢀ75.
[12] Li, X.; Wang, Y.; Kang, L.; Zhu, M.; B. Dai, J. Catal. 2014, 311, 288ꢀ294.
[13] Zhou, K.; Li, B.; Zhang, Q.; Huang, J.Q.; Tian, G.L.; Jia, J.C.; Zhao, M.Q.; Luo,
G.H.; Su, D.S.; Wei, F. ChemSusChem 2014, 7, 723ꢀ728.
10
11
12
13
14
15
16
17
18
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20
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22
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25
26
27
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45
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52
53
54
55
56
57
58
59
60
[14] Li, X.; Pan, X.; Yu, L.; Ren, P.; Wu, X.; Sun, L.; Jiao, F.; Bao, X. Nat. Commun.
2014, 5, 3688ꢀ3694.
[15] Wang, H.; Maiyalagan, T.; Wang, X. ACS Catal. 2012, 2, 781ꢀ794.
[16] Jiao, Y.; Zheng, Y.; Jaroniec,; M.; Qiao, S.Z. J. Am. Chem. Soc. 2014, 136,
4394ꢀ4403.
[17] Deng, D.; Pan, X.; Yu, L.; Cui, Y.; Jiang, Y.; Qi, J.; Li, W.X.; Fu, Q.; Ma,X.;
Xue, Q. Chem.Mater. 2011, 23, 1188ꢀ1193.
[18] Zhao, Y.; Yang, L.; Chen, S.; Wang, X.; Ma, Y.; Wu, Q.; Jiang, Y.; Qian, W.; Hu,
Z. J. Am. Chem. Soc. 2013, 135, 1201ꢀ1204.
[19] Stankovich, S.; Dikin, D.A.; Dommett, G.H.; Kohlhaas, K.M.; Zimney, E.J.;
Stach, E.A.; Piner, R.D.; Nguyen,S.T. ; Ruoff, R.S. Nature 2006, 442,282ꢀ286.
[20] Hummers Jr, W.S.; Offeman, R.E. J. Am. Chem. Soc. 1958, 80,1339ꢀ1339.
[21] Su, Q.; Pang, S.; Alijani, V.; Li, C.; Feng, X.; Müllen, K. Adv. Mater. 2009, 21,
3191ꢀ3195.
[22] Park, S.; Ruoff, R.S. Nat. Nanotechnol. 2009, 4, 217ꢀ224.
[23] Li, D.; Müller, M.B.; Gilje, S.; Kaner, R.B.; Wallace, G.G. Nat. Nanotechnol.
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2
3
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2008, 3, 101ꢀ105.
5
6
7
[24] Becke, A.D. J. Chem. Phys. 1993, 98, 5648ꢀ5652.
8
9
[25] Frisch, M.J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb, M. A.;
Cheeseman, J. R.; Scalmani, G.; Barone, V.; Mennucci, B.; Petersson, G. A., Gaussian
09, Revision C.01; Gaussian, Inc., Wallingford CT, (2010).
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52
53
54
55
56
57
58
59
60
[26] Zheng, Y.; Jiao, Y.; Ge, L.; Jaroniec, M.; Qiao, S.Z. Angew. Chem. Int. Edit. 2013,
125, 3192ꢀ3198.
[27] Niyogi, S.; Bekyarova, E.; Itkis, M.E.; Zhang, H.; Shepperd, K.; Hicks, J.;
Sprinkle, M.; Berger, C.; Lau, C.N.; Deheer, W.A. Nano Lett. 2010, 10, 4061ꢀ4066.
[28] Dikin, D.A.; Stankovich, S.; Zimney, E.J.; Piner, R.D.; Dommett, G.H.;
Evmenenko, G.; Nguyen, S.T.; Ruoff, R.S. Nature 2007, 448, 457ꢀ460.
[29] Ci, L.; Song, L.; Jin, C.; Jariwala, D.; Wu, D.; Li, Y.; Srivastava, A.; Wang, Z.;
Storr, K.; Balicas, L. Nat. Mater. 2010, 9, 430ꢀ435.
[30] RaymundoꢀPinero, E.; CazorlaꢀAmorós, D.; LinaresꢀSolano, A.; Find, J.; Wild,
U. ; Schlögl, R. Carbon 2002, 40, 597ꢀ608.
[31] Park, S.; Hu,Y.; Hwang, J.O.; Lee, E.S.; Casabianca, L.B.; Cai, W.; Potts, J.R.;
Ha, H.W.; Chen, S.; Oh, J. Nat. Commun. 2012, 3, 638ꢀ645.
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Table 1The calculated mass concentrations of different atoms in various graphenesa.
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Sample
GO
C/%
65.51
51.73
89.77
90.40
55.71
57.55
O/%
34.48
37.20
4.76
N/%
ꢀ
B/%
ꢀ
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BꢀG
ꢀ
11.07
ꢀ
NꢀG
5.47
4.97
10.96
9.59
NꢀG (spent)
B, NꢀG
4.63
ꢀ
17.86
17.63
15.47
15.23
B, NꢀG (spent)
aThe elemental composition and elemental content of catalysts were determined by XPS method.
Fig.1 TEM images of: a) GO, b) NꢀG, c) B, NꢀG.
a
GO I
D
/I =0.82
G
N-G I
D
/I =1.01
G
B, N-G I
D
/I =1.08
G
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Raman Shift / cm-1
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C1s
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O1s
N1s
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B1s
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N-G
B-G
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GO
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Binding Energy / ev
18000
16000
14000
12000
10000
8000
c
N-B
N-C
N=C
6000
4000
394
396
398
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402
404
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408
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10000
d
9000
8000
7000
6000
5000
4000
3000
2000
1000
B-C
B-N
182
184
186
188
190
192
194
Binding Energy / ev
Fig.2 (a) Raman spectra for GO, NꢀG and B, NꢀG. (b) XPS survey spectra. (c) Highꢀresolution
N1s spectra of B, NꢀG. (d) Highꢀresolution B1s spectra of B, NꢀG.
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0
a
B, N-G
N-G
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GO
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Reaction Time / min
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1E-3
Au/AC
Hg/AC
SiC@N-C g-C3N4/AC
B, N-G
N-G
Catalysts
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B, N-G
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Temperature / oC
Fig.3 (a) Catalytic reactivity evaluation of: GO, BꢀG, NꢀG and B, NꢀG. Reactions were carried out
at 150 °C, atmospheric pressure, a gas hourly space velocity (GHSV) of 36 hꢀ1, HCl/C2H2=1.15/1
(volume ratio). (b) The TOFs for different catalysts: Au/AC, Hg/AC, SiC@NꢀC, gꢀC3N4/AC, B,
NꢀG, NꢀG. (c) Eads of HCl on different types of active sites in NꢀG and B, NꢀG. Ⅰ: The carbon
atoms bonded with pyridinic N species.Ⅱ: The carbon atoms bonded with pyrrolic N species. Ⅲ:
The carbon atoms bonded with graphitic N species. Please refer to Figure S3ꢀS4 in the Supporting
information for detailed molecular structures and the calculated HOMO states. (d) TPD profile of
GO, NꢀG and B, NꢀG. The samples were preꢀadsorbing by HCl gas for 2 h at a flow rate of 20
mL/min in the microreactor was heated to 150°C. Then it was taken out from the microreactor
when the sample was cooling down to room temperature. Subsequently, Temperatureꢀprogrammed
desorption TPD was conducted using a Micromeritic ASAP 2720 instrument.
Fig. 4 Schematic illustration of acetylene hydrochlorination catalyzed by B, NꢀG catalysts.
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B, N-G
The first regeneration
The second regeneration
0
40
80
120
160
200
240
Reaction Time / min
Fig.5 Conversion of acetylene during 4 h for B, NꢀG and regenerated B, NꢀG. The detailed
regenerated condition: hydrogen atmosphere, 10 mL/min, 600 oC, 2 h.
100
Fresh B, N-G
90
80
Spent B, N-G
70
60
50
40
0
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Temperature / oC
Fig.6 Thermogravimetric analysis curves recorded in air atmosphere of fresh B, NꢀG catalyst and
spent B, NꢀG catalyst.
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