Palladium nanoparticle supported on metal-organic framework derived N-decorated nanoporous carbon as an efficient catalyst for the Suzuki coupling reaction

Article abstract of DOI:10.1016/j.catcom.2014.12.004

A novel catalyst made of Pd nanoparticles supported on the N-doped nanoporous carbon, which was derived from Al-based metal?organic frameworks, was successfully fabricated for the first time. The prepared catalyst was characterized by transmission electron microscopy, scanning electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy and N₂ adsorption. The as-obtained catalyst showed high catalytic activity for the Suzuki-Miyaura coupling reactions. The coupling reactions can be conducted at room temperature. The yields of the products were in the range from90% to 99%. The catalyst can be recycled and reused at least 6 consecutive cycles without any significant loss in catalytic activity.

Full text of DOI:10.1016/j.catcom.2014.12.004

Palladium nanoparticle supported on metal organic framework derived N-
decorated nanoporous carbon as an efficient catalyst for the Suzuki coupling
reaction
Li Zhang, Cheng Feng, Shutao Gao, Zhi Wang, Chun Wang
PII:
DOI:
Reference:
S1566-7367(14)00496-8
doi: 10.1016/j.catcom.2014.12.004
CATCOM 4158
To appear in:
Catalysis Communications
Received date:
Revised date:
Accepted date:
8 October 2014
29 November 2014
3 December 2014
Please cite this article as: Li Zhang, Cheng Feng, Shutao Gao, Zhi Wang, Chun Wang,
Palladium nanoparticle supported on metal organic framework derived N- decorated
nanoporous carbon as an efficient catalyst for the Suzuki coupling reaction, Catalysis
Communications (2014), doi: 10.1016/j.catcom.2014.12.004
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ACCEPTED MANUSCRIPT
Palladium nanoparticle supported on metal organic
framework derived N-decorated nanoporous carbon as
an efficient catalyst for the Suzuki coupling reaction
Li Zhang, Cheng Feng, Shutao Gao, Zhi Wang, Chun Wang
College of Science, Agricultural University of Hebei, Baoding 071001, China
Correspondence: Chun Wang, College of Sciences, Agricultural University of Hebei, Baoding
0
71001, P. R. China. Tel.: +86 312 7528291. E-mail: chunwang69@126.com

Corresponding author. Tel.: +86-312-7528291; fax: +86-312-7528292.
E-mail address: chunwang69@126.com; wangchun@hebau.edu.cn (C. Wang)
1

ACCEPTED MANUSCRIPT
Abstract:
A novel catalyst made of Pd nanoparticles supported on the N-doped nanoporous carbon,
which was derived from Al-based metal-organic frameworks, was successfully fabricated for the
first time. The prepared catalyst was characterized by transmission electron microscopy, scanning
electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy and N adsorption. The
2
as-obtained catalyst showed high catalytic activity for the Suzuki-Miyaura coupling reactions. The
coupling reactions can be conducted at room temperature. The yields of the products were in the
range from 90% to 99%. The catalyst can be recycled and reused at least 6 consecutive cycles
without any significant loss in catalytic activity.
Keywords: Suzuki-Miyaura coupling reaction; Pd catalyst; N-doped nanoporous carbon;
metal-organic frameworks
1
. Introduction
Palladium-catalyzed Suzuki-Miyaura reaction of aryl halides with arylboronic acids is one of
the most powerful methods for constructing biaryl structures [1]. Usually, the cross-coupling
reactions were performed under homogeneous condition employing soluble palladium complex or
organomentallic complexes as catalysts [2]. However, homogeneous palladium catalysts suffer from
the problems including the difficulty to separate and recycle the expensive metal catalysts from
reaction mixture, and the contamination of the ligand residue in the final products [3]. To overcome
the problems mentioned above, heterogeneous palladium catalysts have been employed in recent
years [1]. Pd supported on different materials, such as polymers [4], glass polymer composites [5],
silica [6], clays and zinc ferrite [1], have been used as catalysts for C-C coupling reactions.
However, these materials have one or more limitations in terms of stability, catalytic efficiency, and
2

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recyclability. Therefore, it is still attractive to explore efficient heterogeneous Pd catalyst for the
coupling reactions.
Carbons, especially nanoporous carbon (NPC) materials, have been the most important and
traditionally support for heterogeneous catalyst due to their high specific surface area and large pore
volume in combination with excellent thermal, chemical and mechanical stability [7,8]. Recently,
the utilization of metal-organic-frameworks (MOFs) as templates or precursors for the preparation
of porous carbon materials has been received considerable attention. Due to the highly ordered
porous structures with significant amount of carbon source, MOFs might be the promising
candidates to give highly porous carbon materials under proper thermolysis conditions [9-10]. So
far, several MOFs, such as MOF-5 [11], IRMOF [12], ZIF-63 [13], and ZIF-8 [14], have been
demonstrated as promising templates to construct nanoporous carbons. The MOF-derived porous
carbon materials have found a wide range of applications [15], such as contamination removal [16,
1
7], energy storage [18], electrode materials [14] and carriers for drug delivery systems [16].
However, to the best of our knowledge, there has been no report on the application of MOF-derived
nanoporous carbon as catalyst carriers till now.
It has been demonstrated that the coupling of nitrogen into the carbon materials could enhance
the mechanical, energy-storage properties, and showed more stability for the noble metals (e.g., Pt,
Pd) nanoparticles due to the activation of neighboring carbon atoms caused by the electron affinity
of nitrogen, which is rather beneficial for heterogeneous catalysts [19, 20]. These N-decorated
carbon materials are thermally/chemically stable and have good regeneration ability. In general,
N-decorated porous carbons could be synthesized via amine grafting on the carbon matrix. However,
the postsynthetic incorporation method not only blocks pores but also suffers from leaching and
3

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instability in any subsequent regeneration step. Another synthesis strategy of N-decorated porous
carbons is high temperature pyrolysis of N-containing precursors.
In this report, nitrogen-doped nanoporous carbon was fabricated by direct carbonization of the
nitrogen containing Al-based MOF [21]. The MOF itself acts as the carbon source, the nitrogen
source, as well as the template, thus reducing a number of steps required to modify porous carbon
with nitrogen. In continuation of our interest in exploring efficient catalysts for organic
transformations [3, 22-25], Pd nanoparticle was immobilized onto the as-prepared N-doped NPC for
the first time. To evaluate the catalytic activity of the prepared catalyst, the Suzuki–Miyaura
coupling reaction was employed as the model reaction.
2
2
. Experimental
.1. Materials and methods
Aluminium chloride hexahydrate, 2-amino-1,4-benzene-dicarboxylic acid (H N-H bda),
2
2
sodium borohydride, potassium carbonate and methanol were all obtained from Chengxin Chemical
Reagents Company (Baoding, China). Aryl boronic acids, aryl halides, and palladium chloride
(
PdCl ) were purchased from Aladdin Reagent Limited Company and used as received.
2
The size and morphology of the nanoparticles were observed by transmission electron
microscopy (TEM) using a JEOL model JEM-2011(HR) at 200 kV. Scanning electron microscopy
SEM) studies were conducted on a Hitachi (Model S4800) instrument. The XRD patterns of the
samples were recorded with a Rigaku D/max 2500 X-ray diffractometer using Cu Kα radiation (40
(
o
o
kV, 150 mA) in the range 2θ = 10 - 90 . X-ray photoelectron spectroscopy (XPS) was performed
with a PHI 1600 spectroscope using Mg Kα X-ray source for excitation. The
Brunauer–Emmett–Teller (BET) surface areas were determined from the N adsorption at 300 K
2
4

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using V-Sorb 2800P. The Pd and Al content of the catalyst was determined by means of inductively
coupled plasma atomic emission spectroscopy (ICP-AES) on Thermo Elemental IRIS Intrepid II.
2
.2 Synthesis of N-doped NPC-Pd
Al-MOF was prepared according to the procedure reported by Tim Ahnfeldt [19]. AlCl ·6H O
3
2
(
0.927g, 3.84 mmol), H N-H bda (0.233 g, 1.29 mmol) and methanol (12.35 mL) was transferred
2 2
o
into a 50 mL Teflon-lined stainless steel autoclave and heated to 125 C for 5 h under autogenous
pressure. After the reaction mixture was cooled down to room temperature, the precipitate was
filtered and a yellow microcrystalline product was obtained. The microcrystalline product was
washed with water for three times and dried at 80 °C under vacuum. The carbonization of the
Al-MOF was performed at 800 °C for 10 h with an N flow. The resulting product was denoted as
2
N-doped NPC.
Pd nanoparticles were immobilized on the N-doped NPC by an impregnation method. 50 mg of
N-doped NPC were dispersed in 5 mL water. 6 mg PdCl (0.034 mmol) was added and the mixture
2
was sonicated (200 W, 40 kHz) for 5 min. Then the solution was stirred overnight. After filtration,
the solid was washed with water and dried under vacuum at 80 °C. The obtained solid was
dispersed in 5 mL of water, and then 5.5 mg sodium borohydride (0.0135 mmol) was added. The
pH of the mixture was adjusted to 10 with 25% ammonium hydroxide and the reaction was carried
out at 98 °C for 2 h. The final product, N-doped NPC-Pd, was washed with water and dried in
vacuum at 50 °C. As the preparation process was illustrated in Scheme 1.
For the preparation of aluminium-free N-doped NPC, 100 mg of N-doped NPC powder was
suspended in 35 mL of 10 % HCl and stirred for 5 h. Then the mixture was filtered and the obtained
solid was washed with distilled water. Finally, the N-doped NPC without aluminium oxide or
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o
aluminum was obtained by vacuum drying at 80 C overnight. The aluminium-free N-doped
NPC-Pd was fabricated according to the same procedure for N-doped NPC-Pd except that 50 mg
N-doped NPC was replaced by 50 mg aluminium-free N-doped NPC.
2
.3. General procedure for Suzuki–Miyaura reactions
In a round-bottomed flask, a solution of aryl halide (0.5 mmol), phenylboronic acid (0.6 mmol),
the catalyst (2.2 mg, 0.2 mol%), and K CO (1.45 mmol) were dissolved in a mixture of 4 mL
2
3
H O:EtOH (1:1, v/v). The mixture was stirred at room temperature for a desired reaction time.
2
Upon the completion of the reaction, the reaction mixture was diluted with 10 mL H O and
2
extracted with ethyl acetate (3 × 10 mL). The organic layer was combined, dried with MgSO , and
4
filtered. The filtrate was concentrated by vacuum. The residue was subjected to column
chromatography with petroleum ether/ethyl acetate as the eluent to afford the desired biphenyl
product.
3
3
. Results and discussion
.1. Characterization of the catalyst
The typical TEM and SEM images of N-doped NPC-Pd were shown in Fig. 1. As can be seen
from Fig. 1a, the Pd was well dispersed on the surface of N-doped NPC. The particle size of Pd
nanoparticles was about 5 nm. It can be clearly seen from the SEM image (Fig. 1b) that the
crumpled silk waves-like carbon sheets exist.
Fig. 2 displays the XRD pattern of N-doped NPC-Pd composite. The wide diffraction peak at
2
8
θ = 26° can be indexed to porous carbon [26]. The well-defined peaks around 40°, 47°, 68° and
0
3° can be assigned to (111), (200), (220) and (311) crystal planes of Pd in the composite [3]. The
o
o
o
characteristic peaks of aluminum at 39 , 45 , and 65 can be assigned to (111), (200), and (220)
6

ACCEPTED MANUSCRIPT
o
crystal planes of aluminum. Besides, the peak of -aluminium oxide can also be observed at 16 ,
o
and 20 .
The XPS of N-doped NPC before and after Pd deposition was measured and the images were
shown in Fig. 3. From which we can see that the Al's binding energy was 74.17 eV in the N-doped
NPC sample (Fig. 3a). However, the Al's binding energy increased to 75.01 eV after Pd deposition
on the N-doped NPC sample (Fig. 3b), which indicated that there is a strong interaction between Pd
and Al. The electron transfer between Pd and Al might lead to the change of Al's binding energy.
The XPS of Pd 3d5/2 and 3d3/2 (Fig. 3c) showed that the fitted peaks at 335.5 and 340.98 eV
corresponded to Pd(0), which demonstrated that the Pd species in the N-doped NPC-Pd was present
in the metallic state. The N1s peaks appear at 399.2 eV (Fig. 3d) obviously confirm the presence of
nitrogen in the Al-MOF derived NPC. Nitrogen element in the carbon texture is favorable for the
stabilization of highly dispersed Pd nanoparticles.
The pore properties of the N-doped NPC-Pd composite were investigated by nitrogen
adsorption-desorption isotherms. The general shape of the N sorption isotherms for the N-doped
2
NPC-Pd (Fig. 4A) could confirm the existence of different pore sizes spanning from micro- to
macropores. The steep increase in the adsorbed volume at low relative pressures reveals the
presence of the micropores in the catalyst, and the following small slope observed at
medium relative pressures as well as the desorption hysteresis denotes the existence of the
mesopores while the final almost vertical increase at the relative pressures near 1.0 points to the
presence of macropores. The pore size distributions of the N-doped NPC-Pd calculated from the
nitrogen adsorption branches were shown in Fig. 4B. The BET surface area, total pore volume, total
2
-1
3
-1
adsorption average pore width and SF median pore width are 600 m g , 0.55 cm g , 7.98 nm and 0.72 nm,
respectively.
In older to check the actual loading of Pd and the amount of Al in the N-doped NPC-Pd, the
ICP-AES analysis was performed. The results indicated that the palladium content in N-doped
7

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NPC-Pd and aluminium-free N-doped NPC-Pd was 4.3 wt% and 1.5 wt%, respectively. The results
clearly demonstrated that the presence of aluminum oxide and aluminum in N-doped NPC may be
helpful to stabilize the Pd nanoparticles in the nanoporous carbon. After treatment of the N-doped
NPC with 10% HCl solution, no aluminium element can be detected in the N-doped NPC.
3
.2. Suzuki–Miyaura reactions catalyzed by the prepared catalyst
To evaluate the catalytic performance of the as-obtained catalyst and optimize the reaction
conditions of the Suzuki coupling reaction, the coupling of phenyl bromide and phenyl boronic acid
was selected as a model reaction. The results indicated that N-doped NPC-Pd could catalyze the
reaction efficiently even at room temperature. When the amount of the catalyst was 0.2 mol%, the
coupling reaction can be completed within 1 h to afford the corresponding biphenyl in 97% yield
with EtOH/H O (1:1, v/v) as the solvent. The reaction does not take place in the absence of catalyst
2
or using N-doped NPC as a catalyst, which indicated that aluminium oxide containing in the
N-doped NPC has not catalytic activity for the coupling reaction. However, when the N-doped NPC
was treated by 10 % HCl for 5 h to remove the aluminium oxide or aluminum, only 69% yield of
biphenyl was obtained with the corresponding aluminium–free NPC-Pd as a catalyst. The results
clearly demonstrated that the presence of aluminum oxide and aluminum in N-doped NPC may be
helpful to improve the dispersion of the Pd nanoparticles. In general, regardless of the exact
mechanism of the reaction, the catalytic activity of nanocatalyst is determined by the size of
nanoparticles. The smaller the nanoparticle is, the more effective the catalytic activity become.
N-doped NPC-Pd exhibited high activities due to the good dispersion and small size of the Pd
nanoparticles. With the commercially available Pd supported on activated carbon (5% Pd/C, the
most often used catalyst in heterogeneous Pd catalyzed coupling reactions) as the catalyst, only
8

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7
8% yield of biphenyl was obtained under the same conditions.
The influence of the amount of catalyst was also investigated. The results indicated that 0.2
mol% amount of N-doped NPC-Pd was sufficient to guarantee a clean and complete conversion.
When the amount of N-doped NPC-Pd increased from 0.02 mol% to 0.20 mol%, the yield of
biphenyl increased from 80% to 97%. When the amount of catalyst was higher than 0.20 mol%, the
yield of biphenyl almost remained constant.
To generalize the application of the N-doped NPC-Pd catalyst, the coupling reactions of
various substituted aryl halides and phenylboronic acids were carried out in the presence of K CO
2
3
using H O:EtOH (1:1) as environmentally benign solvents. The results are summarized in Table 1.
2
For all the substrates, the reactions could be completed in 0.5-3 h with the substrates having either
electron-donating groups (Entries 2-4, 10), such as –CH , -OCH , or electron-withdrawing groups
3
3
(
Entries 5-9), such as -COCH , -OH. The yields of the corresponding coupled products were in the
3
range from 90% to 99%. Additionally, aryl chlorides was chosen as the challenging substrates
Table 1 entry 14), however, the catalytic system was less effective even prolonged reaction time,
(
which might be ascribed to the strong strength of the C-Cl bond, whose bond dissociation energy
was 96 kcal/mol [27].
The recyclability of the catalyst was further investigated because the recycling of the
heterogeneous catalysts is desirable in practical applications. The Suzuki-Miyaura cross-coupling
reaction between bromobenzene and phenyl boronic acid catalyzed by 0.2 mol% of N-doped
NPC-Pd was chosen as a model reaction. The results indicated that N-doped NPC-Pd can be reused
6
times without significant loss of its catalytic activity (Fig. 5). Good reusability mainly attributed
to the high specific surface area N-doped NPC. Moreover, nitrogen element in carbon texture is also
9

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playing an important role for stabilizing highly dispersed Pd nanoparticles. Therefore, the Pd NPs
deposited on N-doped NPC are not easily leached during catalytic processes.
4
. Conclusions
In this paper, N-doped nanoporous carbon was fabricated by direct carbonization of the
nitrogen containing Al-based MOF and which was used as the carrier material for palladium
nanoparticle. The as-obtained heterogeneous catalyst, N-doped NPC-Pd, exhibited excellent
catalytic activity for the Suzuki cross-coupling reaction even when the reaction was carried out at
room temperature for a relative short time. The catalyst can be readily recovered and reused at least
6
times without significant loss of its catalytic activity. The present research might highlight the
development of high catalytic activity heterogeneous catalysts by using MOF-derived porous
carbon as hosts for ultrafine metal nanoparticles.
Acknowledgements
This work was financially supported by the National Natural Science Foundation of China (no.
3
1171698, 31471643), the Innovation Research Program of Department of Education of Hebei for
Hebei Provincial Universities (LJRC009), Natural Science Foundation of Hebei Province
(
B2011204051) and the Natural Science Foundation of Agricultural University of Hebei
LG201404).
(
References
[
[
[
1] S.S. Shendage, A.S. Singh, J.M. Nagarkar, Tetrahedron Lett. 55 (2014) 857-860.
2] H. Sakurai, T. Tsukuda, T. Hirao, J. Org. Chem. 67 (2002) 2721–2722.
3] N.Z. Shang, C. Feng, H.Y. Zhang, S.T. Gao, R.X. Tang, C. Wang, Z. Wang, Catal. Commun. 40
1
0

ACCEPTED MANUSCRIPT
(
2013) 111-115.
4] J.F. Hu, Y.P. Wang, M. Han, Y.M. Zhou, X.Q. Jiang, P.P. Sun, Catal. Sci. Technol. 2 (2012)
332–2340.
[
2
[
[
5] S.S. Shendage, A.S. Singh, J.M. Nagarkar, Tetrahedron Lett. 54 (2013) 3457-3461.
6] Y.Q. He, N.N. Zhang, Q.J. Gong, Z.L. Li , J.P. Gao, H.X. Qiu, Mater. Chem. Phy. 134 (2012)
5
85-589.
[
[
[
7] J.K. Sun, Q.Xu, Energy Environ. Sci. 7 (2014) 2071–2100.
8] W. Chaikittisilp, K. Ariga, Y.Yamauchi, J. Mater. Chem. A, 1 (2013) 14-19.
9] F. Afsahi, H. Vinh-Thang, S. Mikhailenko, S. Kaliaguine, J. Power Sources 239 (2013)
4
15-423.
[
[
10] H.B. Aiyappa, P.Pachfule,R. Banerjee, S. Kurungot, Cryst. Growth Des. 13 (2013) 4195-4199.
11] J.S. Li, S.L. Li, Y.J. Tang, K. Li, L. Zhou, N. Kong, Y.Q. Lan, J.C. Bao, Z.H. Dai, Sci. Reports
4
(2014) 5130-5138.
[
[
12] S.J. Yang, T. Kim, K. Lee, Y.S. Kim, J. Yoon, C.R. Park, Carbon 71 (2014) 294-302.
13] Y.Y. Lu, W.W. Zhan, Y. He, Y.T. Wang, X.J. Kong, Q. Kuang, Z.Q. Xie, L. Zheng, ACS Appl.
Mater. Inter. 6 (2014) 4186-4195.
[
[
[
14] H.L. Jiang, B. Liu, Y.Q. Lan, K. Kuratani, T. Akita, H. Shioyama, F. Zong, Q. Xu, J. Am.
Chem. Soc. 133 (2011) 11854-11857.
15] S.J. Yang, T. Kim, J.H. Im, Y.S. Kim, K. Lee, H. Jung, C.R. Park, Chem. Mater. 24 (2012)
4
64-470.
16] M. Hu, J. Reboul, S. Furukawa, N.L. Torad, Q. Ji, P. Srinivasu, K. Ariga, S. Kitagawa, Y.
Yamauchi, J. Am. Chem. Soc. 134 (2012) 2864-2867.
11

ACCEPTED MANUSCRIPT
[
17] N.L. Torad, M. Hu, S. Ishihara, H. Sukegawa, A.A. Belik, M. Imura, K. Ariga, Y. Sakka, Y.
Yamauchi, Small 10 (2014) 2096-2107.
[
[
[
18] X.L. Yan, X.J. Li, Z.F. Yan, S. Komarneni, Appl. Surf. Sci. 308 (2014) 306-310.
19] M. Li, X. Xu, Y. Gong, Z. Wei, Z. Hou, H. Li, Y. Wang, Green Chem. 16 (2014) 4371.
20] H.L. Jiang, B.Liu, Y.Q. Lan, K. Kuratani, T. Akita, H. Shioyama, F. Zong, Q. Xu, J. Am.
Chem. Soc. 133 (2011) 2362-2365.
[
[
[
21] T. Ahnfeldt, N. Guillou, D. Gunzelmann, I. Margiolaki, T. Loiseau, G. Ferey, J. Senker, N.
Stock, Angew. Chem. Int. Ed. 48 (2009) 5163-5166.
22] N.Z. Shang, S.T. Gao, X. Zhou, W.H. Liu, C. Wang, Z. Wang, RSC Adv. 4 (2014)
5
4487–54493.
23] H.Y. Zhang, S.T. Gao, N.Z. Shang, C. Feng, C. Wang, Z. Wang, RSC Adv. 4 (2014)
1328-31332.
3
[
[
24] S.T. Gao, N.Z. Shang, C. Feng, C. Wang, Z. Wang, RSC Adv. 4 (2014) 39242-39247.
25] N.Z. Shang, S.T. Gao, C. Feng, H.Y. Zhang, C. Wang, Z. Wang, RSC Adv. 3 (2013)
2
1863-21868.
[
[
26] H.S. Bo Liu, Tomoki Akita, Q. Xu, J. Am. Chem. Soc. 130 (2008) 5390–5391.
27] F. Durap, M.Rakap, M. Aydemir, S. Özkar, Appl. Catal. A: Gen. 382 (2010) 339–344.
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Table 1 Suzuki–Miyaura coupling of arylboronic acids and aryl halides catalyzed by N-doped
a
NPC-Pd
b
Entry
1
Aryl halides
Arylboronic acids
t/ h
1
Yield /%
Br
B(OH)2
97
2
3
Br
CH3
B(OH)2
B(OH)2
1
1
95
90
CH3
Br
4
5
Br
Br
Br
Br
OCH3
OH
B(OH)2
B(OH)2
B(OH)2
B(OH)2
B(OH)2
B(OH)2
B(OH)2
1
1
94
94
98
96
95
99
97
c
6
NO2
COH
COCH3
NO2
0.5
1
7
8
Br
1
c
9
I
0.5
1
1
1
0
1
I
OCH3
CH3
Br
Br
Br
1.5
1
90
92
B(OH)2
H C
3
1
1
2
3
B(OH)2
CH3
1
3
94
14
B(OH)2
d
1
4
B(OH)2
a
Reaction conditions: bromobenzene (0.5 mmol), phenyl boronic acid (0.6 mmol), K CO (1.5 mmol), solvent: 2
2
3
1
3

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mL ethanol + 2 mL H O, catalyst: N-doped NPC-Pd (0.2 mol%), Room temperature.
2
b
Isolated yield based on column chromatography;
c
d
o
The reaction temperature is 50 C.
o
The reaction temperature is 60 C.
self-assembly
carbonization
Al-MOF
Pd
impregnation
reduction
3
+
Al
H N-H bd
2
2
N-doped NPC-Pd
Scheme 1. Schematic illustration of the synthetic processes of N-doped NPC-Pd
a
b
Fig. 1. TEM (a) and SEM (b) images of N-doped NPC-Pd. The inset in (a) is the HRTEM image.
1
4

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1
000
*
#
Al O3
&
2
C
*
*
8
6
4
2
00
00
00
00
0
&
%
Pd
Al
#
%
&
%
%
&
&
2
0
40
60
80
Two-Theta (degree)
Fig. 2. XRD patterns of N-doped NPC-Pd
8000
7000
6000
5000
4000
3000
2000
1000
0
30000
a
Al 2p
b
Al 2p
2
2
5000
0000
15000
0000
1
5
000
0
65
70
75
80
85
65
70
75
80
85
Binding Energy
Binding Energy
8
8
8
8
800
Pd 3d5/2
1
1
1
1
3000
2000
1000
0000
c
d
N1s
600
400
200
Pd 3d3/2
8000
7
7
7
7
800
600
400
200
9
8
7
6
000
000
000
000
7000
3
92 394 396 398 400 402 404 406 408 410 412
3
30 332 334 336 338 340 342 344 346 348 350
Binding Energy
Binding Energy
Fig. 3. The XPS image of N-doped NPC (a) and N-doped NPC-Pd (b, c and d).
1
5

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8
7
6
5
4
3
2
1
00
00
00
00
00
00
00
00
0
A
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
B
0
.0
0.2
0.4
0.6
0.8
1.0
0.5
1.0
1.5
2.0
2.5
Relatave pressure(P/PO)
Pore width (nm)
Fig. 4. The nitrogen adsorption-desorption isotherm (A) and pore size distributions (B) of the
N-doped NPC-Pd
1
00
8
6
4
2
0
0
0
0
0
1
2
3
4
5
6
Cycle Number
Fig. 5. Recyclability of the N-doped NPC-Pd for the Suzuki-Miyaura reaction
1
6

ACCEPTED MANUSCRIPT
Graphical abstract
N-doped nanoporous carbon was fabricated by direct carbonization of the nitrogen containing
Al-based MOF and which was used as the carrier material for palladium nanoparticle for the first
time. The as-obtained heterogeneous catalyst, N-doped NPC-Pd, exhibited excellent catalytic
activity for the Suzuki cross-coupling reaction.
self-assembly
carbonization
Al-MOF
Pd
impregnation
reduction
3
+
Al
H N-H bd
2
2
N-doped NPC-Pd
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ACCEPTED MANUSCRIPT
Highlights
►
N-doped porous carbon (NPC) was synthesized by direct carbonization of
Al-based MOF. ► Heterogeneous catalyst, NPC-Pd, was prepared for the first time.
NPC-Pd exhibited excellent catalytic activity for the Suzuki coupling reaction.
►
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