A facile synthesis of microporous organic polymers for efficient gas storage and separation

Article abstract of DOI:10.1039/c4ta05349d

A series of porous hyper-cross-linked polymers with excellent physiochemical stability have been designed and prepared facilely through template-free Friedel-Crafts alkylation reactions between benzene/biphenyl/1,3,5-triphenylbenzene as co-condensing rigid aromatic building blocks and 1,3,5-tris(bromomethyl)benzene or 1,3,5-tris(bromomethyl)-2,4,6-trimethylbenzene as cross-linkers under the catalysis of anhydrous AlCl₃ or FeCl₃. The systematic study of gas uptake ability shows that anhydrous AlCl₃ is a much more effective catalyst than anhydrous FeCl₃. The synthesized polymers are thermally stable and are predominantly microporous with high surface areas up to 1783 m² g^-1. In addition, they exhibit high H₂ and CO₂ uptake capacity/selectivity. Among these materials, C1M3-Al has the highest H₂ uptake capacity at 77 K and 1 bar (19.1 mg g^-1) and CO₂ uptake capacity at 273 K and 1 bar (181 mg g^-1); the best CO₂/N₂ (15/85) selectivity calculated by IAST at 273 K and 1 bar belongs to C1M2-Al (32.3). Moreover, the synthesis route exhibits cost-effective advantages, which are essential for scale-up preparation, thus showing great potential for clean energy applications.

Full text of DOI:10.1039/c4ta05349d

View Article Online
View Journal
Journal of
Materials Chemistry A
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: G. Liu, Y. Wang,
C. Shen, Z. Ju and D. Yuan, J. Mater. Chem. A, 2014, DOI: 10.1039/C4TA05349D.
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Accepted Manuscripts are published online shortly after
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. We will replace this Accepted Manuscript with the edited
and formatted Advance Article as soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the Ethical guidelines still
apply. In no event shall the Royal Society of Chemistry be held
responsible for any errors or omissions in this Accepted Manuscript
or any consequences arising from the use of any information it
contains.
www.rsc.org/materialsA

Page 1 of 9
Journal of Materials Chemistry A
Journal Name
RSCPublishing
View Article Online
DOI: 10.1039/C4TA05349D
ARTICLE
A facile synthesis of microporous organic polymers
for efficient gas storage and separation
Cite this: DOI: 10.1039/x0xx00000x
a,b
a,b
a
a
Guoliang Liu, Yangxin Wang, Chaojun Shen, Zhanfeng Ju and Daqiang
Yuan
*
,a
Received 00th January 2012,
Accepted 00th January 2012
A series of porous hyper-cross-linked polymers with excellent physiochemical stability have been
designed and prepared facilely through template-free Friedel-Crafts alkylation reactions between
benzene / biphenyl / 1,3,5-triphenylbenzene as co-condensing rigid aromatic building blocks and
1,3,5-tris(bromomethyl)benzene or 1,3,5-tris(bromomethyl)-2,4,6-trimehylbenzene as cross-linkers
DOI: 10.1039/x0xx00000x
www.rsc.org/
under the catalysis of anhydrous AlCl
anhydrous AlCl is a much more effective catalyst than anhydrous FeCl
thermally stable and are predominantly microporous with high surface areas up to 1783 m g . In
addition, they exhibit high H and CO uptake capacity/selectivity. Among these materials, C1M3-Al
has the highest H uptake capacity at 77 K and 1 bar (19.1 mg·g ) and CO
3
or FeCl
3
. The systematic study of gas uptake ability shows that
3
3
. The synthesized polymers are
2
-1
2
2
-
1
2
2
uptake capacity at 273 K and
-
1
1
bar (181 mg·g ); the best CO /N (15/85) selectivity calculated by IAST at 273 K and 1 bar belongs to
2 2
C1M2-Al (32.3). Moreover, the synthesis route exhibits cost-effective advantages, which are essential
for scale-up preparation, thus showing great potential for clean energy applications.
Introduction
the presence of cheap, readily available Lewis acids as catalysts.
They have the advantages of low production cost and easy scale
Recently, climatic warming due to the rapid consumption of
fossil fuels and biomass has gradually produced disastrous
consequences. How to effectively capture CO2 has been a
production. There are two common approaches through Friedel-
Crafts reaction to synthesize HCPs: one is direct polymerization
of monomers, and the other one is intermolecular and
intramolecular post crosslinking of preformed polymer
1
common topic among the global scientific community. The
conventional CO2 capture process based on alkanolamine
solvents has significant drawbacks such as high energy
consumption, corrosion of equipment and some environmental
13
chains. Efforts made to explore such new hyper-cross-linked
materials have achieved well-pleasing fruit. Some of these
polymers featured great capability in carbon-capture. For
example, Cooper’s group reported an alcohol-containing
issues. In order to solve those problems, the new generation
2
CO capture technologies must be developed on a global scale.
2
polymer network with a significantly higher CO uptake of 174
2
Porous materials relying on physical adsorption are potential
candidates for CO capture because of their low regeneration
energy consumption, high CO sorption capacity and synthetic
diversification. Microporous organic polymers (MOPs) are an
important class of porous materials which are constructed from
monomers as organic building blocks and have shown great
potential in a variety of applications, such as gas storage and
-1
13c
mg·g at 1 bar and 273 K. Recently, Dai’s group reported a
2
new triazine and carbazole bifunctionalized task-specific
2
-1
polymer whose CO uptake of 180 mg·g at 1 bar and 273 K is
2
3
14
among the highest uptake in porous HCPs. Experimental
results indicate that the innate abilities of the porous HCPs for
the gas storage or separation are correlated to their pore
structure including specific surface area, pore geometry, pore
volume and pore size distribution. The Brunauer-Emmett-Teller
4
separation, catalysis, chemical sensing, etc. MOPs is a wide
5
concept which includes polymers of intrinsic microporosity
(
BET) specific surface area is a very important parameter in the
6
7
(
PIMs), conjugated microporous polymers (CMPs), covalent
pore structure for the HCPs, which can be tuned in the range of
8
organic frameworks (COFs), hyper-cross-linked polymers
2
-1
3
00-2090 m ·g by manipulating the structure of the monomers
9
10
(
HCPs), crystalline triazine-based frameworks (CTFs),
13h
and/or reaction parameters. Therefore, designing monomer
and optimizing the synthetic condition to synthesize HCPs with
higher specific surface areas are critical for the applications
such as gas storage or separation.
1
1
porous polymer networks (PPNs) and porous aromatic
1
2
frameworks (PAFs). However, most MOPs were obtained via
cross-coupling reactions catalysed by precious metal catalysts,
which limited their practical applications.
HCPs with high microporosity is a subclass of MOPs,
which were prepared by Friedel-Crafts alkylation reaction in
In the classical Friedel-Crafts alkylation reaction, benzyl
bromides could also be used as alkylating agents and the small
This journal is © The Royal Society of Chemistry 2013
J. Name., 2013, 00, 1‐3 | 1

Journal of Materials Chemistry A
Page 2 of 9
Journal Name
ARTICLE
gases adsorptive property of the polymers resulting from Table 1 Elemental analysis data of the polymers.
tritopic benzyl bromides have never been systematically
Calculated (%)
FouVniedw(%Art)icle Online
DOI: 1C0 .1039/C4TA H0 5349D
investigated. In addition, almost all the HCPs were carried out
Materials
C1M1-Al
(C36H )
30 n
C1M2-Al
(C H )
54 42 n
C1M3-Al
24 n
(C33H )
C2M1-Al
(C H )
42 42 n
C2M2-Al
60 54 n
(C H )
C2M3-Al
36 30 n
(C H )
C1M3-Fe
(C H )
33 24 n
C2M3-Fe
C
H
1
3h
by using anhydrous FeCl as catalyst. However, we found
3
9
3.46
6.54
81.56
88.60
88.46
86.20
89.40
88.46
64.88
70.86
5.71
5.50
5.49
6.46
6.03
5.88
3.68
4.58
that the gas sorption properties of the polymers were largely
affected by the structure of the polymers which were relevant to
the activity of the reaction catalyst. Here we demonstrate that
93.87
6.13
5.75
7.74
7.02
6.54
5.75
6.54
9
9
9
9
4.25
2.26
2.98
3.46
1
,3,5-tris(bromomethyl)benzene
(C1
)
and
1,3,5-
tris(bromomethyl)-2,4,6-trimehylbenzene) (C2) are firstly used
as cross-linkers and co-condensed with ordinary aromatic
compounds of different sizes to construct a series of cost-
effective porous materials in the presence of anhydrous FeCl3
or AlCl as catalysts. The adsorption of CO and H as well as
3
2
2
the separation of CO /N were evaluated and compared in order
94.25
3.46
2
2
to deeply study the effect of catalyst and building block features
on the pore structures and the properties of target frameworks.
9
(C36
30 n
H )
Physical characterization
Fourier transform infrared (FT-IR) spectra of the MOPs were
Experimental Section
−
1
Materials
recorded on KBr pellets in the 4000−400 cm range using a
Perkin−Elmer Spectrum One FT-IR spectrometer. Elemental
analyses (C, H, and N) were performed on an Elementar Vario
Reagents and solvents were purchased from commercial
suppliers and used without further purification, unless
otherwise indicated. Dichloromethane (DCM) was dried by
activated molecular sieve. 1,3,5-Tris(bromomethyl)benzene and
1
3
MICRO elemental analyzer. Solid-state C CP/MAS NMR
were performed on a Bruker SB Avance III 500 MHz
spectrometer with a 4-mm double-resonance MAS probe, a
sample spinning rate of 9.0 kHz, a contact time of 2 ms and
pulse delay of 5 s. A recycling delay of 10 s was used and 4096
scans were typically acquired for each spectrum. Thermal
gravimetric analysis data were obtained with a NETZSCH STA
1
,3,5-Tris(bromomethyl)-2,4,6-trimehylbenzene
were
1
5
synthesized following the published procedures.
Synthesis of hyper-cross-linked porous polymers
All the microporous organic polymer networks were
synthesized by Friedel-Crafts alkylation of benzene, biphenyl,
or 1,3,5-triphenylbenzene using 1,3,5-tris(bromomethyl)-2,4,6-
trimehylbenzene or 1,3,5-tris(bromomethyl)benzene as cross-
linker promoted by anhydrous AlCl3 or FeCl3 in similar
procedures. The preparation of sample C1M1-Al will serve as
4
49C analyzer. All samples and reference (Al O ) were
2 3
enclosed in a platinum crucible and were heated from 25 °C to
-
1
1
000 °C at a rate of 10 °C min under a N atmosphere.
2
Powder X-ray di
Rigaku-DMAX 2500 di
(
ff
raction (PXRD) patterns were collected on a
ractometer with Cu Kα radiation
λ=1.5406 Å) at a scanning rate of 1° /min for 2θ ranging from
ff
an example: AlCl (anhydrous 500 mg, 3.75 mmol), 1,3,5-
3
5
° to 60°. Scanning Electron Microscopy (SEM) experiments
tris(bromomethyl)benzene(180 mg, 0.5 mmol) and benzene (60
mg, 0.75 mmol) were added to a 100 ml flask, and then 20 ml
dry DCM was added to it. The mixture was stirred under
nitrogen protection at 40 °C for 24 h to form the network. The
colour of the mixture darkens with time. The resulting
precipitate was washed three times with diluted hydrochloric
acid, methanol, DCM and acetone, respectively, and then
extracted by methanol in a Soxhlet for 24 h, and finally dried
were carried on a JSM 6700 at 10.0 kV. EDS was performed
using a JSM 6700 microscope. Before measurement, the
samples were sputter-coated with gold to facilitate conduction.
Metal elemental analysis was carried out on an Ultima-2 ICP
emission spectrometer. The textural properties of various
sorbents were measured by N sorption isotherms at 77 K using
2
a Micromeritics ASAP 2020 surface area and porosimetry
analyser. All samples were degassed at 160 °C for 24 h under
conditions of dynamic vacuum before analysis. The specific
o
under reduced pressure at 160 C for 24 h for further tests.
Elemental analysis (%) Calcd. for (C H ) : C 93.46, H 6.54
3
6
30 n
surface areas for N were calculated using the BET model over
(
based on the 3.0 mmol starting material of benzene completely
2
a relative pressure (P/P ) range of 0.05 – 0.15. Total pore
reacted with 2.0 mmol C1); found: C 81.56, H 5.71.
0
volumes were calculated from the uptake at a relative pressure
of 0.995. Pore size distributions were calculated from the
adsorption isotherms by no-local density functional theory
The same procedure was followed for the synthesis of other
HCPs (Table 2) and the C, H elemental analysis data for all
polymers are listed in Table 1. The deviations between
calculated and found values are expected for such polymers due
to incomplete combustion and trapped adsorbates including
catalyst, gases and water vapour within the pore structure,
(
NLDFT) method. N2 adsorption isotherm at 273 K was
measured in order to evaluate the adsorption selectivity of
CO /N . Hydrogen adsorption isotherms were measured on the
2
2
9
b, 13e, 13i, 16
ASAP 2020 at 77 K and 87 K up to 1.13 bar. Carbon dioxide
adsorption isotherms were also collected on the ASAP 2020 at
which are consistent with the literature reported.
2
73 K, 283 K and 298 K, respectively.
2
| J. Name., 2012, 00, 1‐3
This journal is © The Royal Society of Chemistry 2012

Page 3 of 9
Journal Name
Journal of Materials Chemistry A
ARTICLE
Results and Discussion
indicates some bromomethyl groups may remain unsubstituted
under the investigated reaction conditions. SimilarVierwesAurtlictsle wOnelirnee
Synthesis and characterization of HCPs
also reported by other group with residual chlorine or oxygen in
DOI: 10.1039/C4TA05349D
Meanwhile, only relatively small amounts of
5
, 9a
We used 1,3,5-tris(bromomethyl)benzene (C1) and 1,3,5- the HCPs.
tris(bromomethyl)-2,4,6-trimehylbenzene (C2) as 3-connected residual iron or aluminium were found in all these networks
cross-linkers to construct a series of porous polymers. The (Table S2, ESI†), indicating that most of the catalysts were
polymers were readily obtained in good yields under mild removed during the workup procedure.
reaction conditions by mixing cross-linker, monomer, catalyst,
dry dichloride methane (DCM), and stirring at 40 °C for 24 h.
The synthesis route for these polymer networks is present in
Scheme 1. The resulting precipitate was fully washed three
times with dilute hydrochloric acid, methanol, acetone and
DCM, respectively. The product was purified through Soxhlet
extractor in methanol for 24 h in order to remove all the
remaining catalyst and monomer. The product was obtained as
brownish power after dried under reduced pressure at 160 °C
for 24 h.
AlCl
3
, DCM
C1M1-Al, C2M1-Al
C1M2-Al, C2M2-Al
4
0 oC, 24 h
M1
M2
Br
3
AlCl , DCM
4
0 oC, 24 h
R
R
+
Br
13
Fig. 1 Experimental C CP‐MAS NMR spectra of the polymer networks. Asterisks
AlCl
3
, DCM
denote spinning sidebands.
R
Br
C1M3-Al, C2M3-Al
C1M3-Fe, C2M3-Fe
4
0 oC, 24 h
C1: R = H
C2: R = Me
The power X-ray diffraction measurement showed that all
the samples were amorphous (Fig. S4, ESI†). The molecular
details of the samples were confirmed by Fourier transform
FeCl
3
, DCM
4
0 oC, 24 h
M3
Scheme 1. Synthesis route for the HCPs
13
infrared (FTIR) spectroscopy, C cross-polarization magic-
angle spinning (CP/MAS) NMR and elemental analysis (EA).
In the FTIR spectrum of all samples, peaks near 1600, 1500,
-
1
and 1450 cm were attributed to aromatic ring skeleton
1
3
vibrations (Fig. S3, ESI†). The C CP/MAS NMR of all tested
samples are similar to the porous polymers obtained using
1
3b
formaldehyde dimethyl acetal (FDA) as cross-linker.
The
Br
resonance peaks near 139 and 130 ppm can be easily ascribed
to the substituted aromatic carbon and non-substituted aromatic
carbon, respectively. All samples displayed methylene
resonance peaks near 35 ppm, supporting the formation of
methylene linker after Friedel-Crafts reaction and indicating the
presence of the monomer moiety within the polymer network.
+
AlCl3, DCM
Br
Br
M3
C1
C1M3-Al
Scheme 2 Schematic presentation of the linkage (blue) between the monomers
as well as the structure of the resulted polymers (C1M3‐Al as an example)
C2-based polymers of C2M1-Al, C2M2-Al and C2M3-Al
showed strong methyl resonance peaks near 16 ppm (Fig. 1).
The resonance peaks of different samples revealed a little
variation according to the character of the monomers and the
knitting degree.
We chose C1 or C2 as 3-connected building blocks and
reacted with 1,3,5-triphenylbenzene (M3) in the presence of
anhydrous AlCl or FeCl , respectively, to evaluate the effect of
3
3
catalysts on the structural features of the porous polymers. In
The morphology of the porous polymers was investigated
by scanning electron microscopy (SEM). The SEM images
revealed the formation of aggregated nanoparticles for all these
polymers (Fig. S6-S13, ESI†). The materials were found to be
stable in most common organic solvents and showed no
degradation towards humidity. Further analyses of the polymers
by thermal gravimetric analysis (TGA) showed that all the
samples were stable up to 300 °C under nitrogen atmosphere
and retained more than 60-85 % of their mass even at 1000 °C
addition, C1 or C2 were reacted with benzene (M1), biphenyl
(M2), and 1,3,5-triphenylbenzene (M3), respectively, to afford
six polymers under the catalysis of anhydrous AlCl (Scheme 1
3
and 2).
Theoretically, each bromomethyl group should be converted
into a methylene bridge by elimination of one hydrogen
bromide molecule. But in fact, the residual bromine in the
resulting polymers was found according to Energy Dispersive
Spectrometer (EDS) (Table S1, Figure S1, ESI†), which
This journal is © The Royal Society of Chemistry 2012
J. Name., 2012, 00, 1‐3 | 3

Journal of Materials Chemistry A
Page 4 of 9
Journal Name
ARTICLE
(
Fig. S2, ESI†), suggesting a good thermal stability due to the anhydrous FeCl
3
. As a result, anhydrous AlCl
the catalyst in the following polymers synthesis.
3
was chosen as
highly cross-linked network of the polymers.
View Article Online
DOI: 10.1039/C4TA05349D
Porosity and gas sorption studies
Permanent porosity was retained as expected even though
removing the solvent, owing to numerous rigid knitting points
preventing the framework collapse of the material. The surface
area and porosity parameters of the samples were analysed by
standard nitrogen sorption analysis at 77 K. As shown in Fig. 3,
these porous polymers display a Type I isotherm with type IV
character at higher relative pressures. The adsorption isotherms
are characterized by a steep nitrogen gas uptake at low relative
pressure (P/P <0.1), indicating permanent microporosity of all
0
tested samples. The C2-based samples show different degree of
hysteresis loop indicating partial mesoporosity. The gradual
increase of nitrogen adsorption of the polymers at medium and
0
high pressure region (P/P =0.8-1.0) indicates the presence of
macroporous structure which can be interpreted as loose
packing induced by inter-particulate voids in these materials. A
small hysteresis is observed in the whole pressure range of
desorption for all samples, which is consistent with the swelling
11 8
effect as a result of gas sorption.
Fig. 2 The effects of the catalyst on porosity. (a) BET surface area. (b) micropore
2 2
volume. (c) H uptake at 77 K and 1 bar. (d) CO uptake at 273 K and 1 bar.
1
200
000
C1M1-Al
C1M2-Al
C1M3-Al
C2M1-Al
C2M2-Al
C2M3-Al
700
00
1
6
Effect of catalyst on the porosity of HCPs
800
600
400
200
0
500
400
300
The Friedel-Crafts alkylation reaction can be catalysed by
anhydrous AlCl , FeCl or other Lewis acids. David C.
3 3
Sherrington and his co-worker have explored the effect of the
catalyst on the BET surface area of the resulting polymers and
2
00
00
0
1
0
.0
0.2
0.4
0.6
0.8
1.0
0.0
0.2
0.4
0.6
0.8
1.0
they found that FeCl
catalyst than AlCl and SnCl
almost all of the following HCPs were synthesized by using
anhydrous FeCl as catalyst. However, the activities of catalyst
3
is a much more effective Lewis acid
P/P0
P/P0
1
3h
3
4
.
Influenced by this result,
Fig. 3
(
2
N sorption isotherms of the C1MX‐Al and C2MX‐Al (X = 1, 2 ,3) at 77 K
filled, adsorption; open, desorption).
3
are closely related to the different reactants and reaction
conditions. In our case, the C1M3 and C2M3 were selected to
The characterization of pore structure including surface area
and the pore volume and gas sorption for these porous polymers
are summarized in Table 2. The BET method was applied to
determine the surface areas of these samples. As there are
macropores in these polymers, the selection of isotherm points
for BET surface area calculations had to be subjected to the
carry on a performance contrast experiment of anhydrous AlCl
or FeCl . The result showed that the two catalysts had no
substantial difference in synthetic efficiency. However, the
porosity of samples catalysed by AlCl outperformed that of
samples catalysed by FeCl . Fig. 2 clearly demonstrates that the
BET surface areas, micropove volume, H uptake and CO
3
3
3
3
0 0
values of V(P -P) which increased continuously with P/P in
2
2
addition to a linear BET plot and a positive value of the c
parameter (Fig. S14-S21, ESI†). The BET surface areas are in
uptake of the polymers with anhydrous AlCl
significantly superior to those with anhydrous FeCl
It is not entirely clear why such significant differences arise
between these species, however it may be that anhydrous AlCl
is the more powerful and common used catalyst than anhydrous
3
as catalyst are
as catalyst.
2
-1
3
the range of 609 to 1783 m ·g for this series. It is interesting
to note that the BET surface area of the polymers based on the
2
-1
3
same cross-linker dramatically increase (from 688 m ·g of
2
-1
2
-1
C1M1-Al, 1164 m ·g of C1M2-Al to 1783 m ·g of C1M3-
Al) when the size of the monomer increase. This trend is
1
7
FeCl
higher polymerization degree with the conversion of more
CH Br groups into methylene bridges, which confirmed by
3 3
. The resulting polymers in the presence of AlCl show a
13b
different from which obtained by Tan’s group. Their research
2
showed that benzene-based rather than M3-based network
element analysis (high C and H contents) and EDS (low Br
content). The networks with higher degrees of condensation are
less able to collapse and densify, thus leading to higher levels
using FDA as cross-linker had the highest BET surface area,
which was high up to 1391 m ·g . When the AlCl was used as
3
catalyst, the polymers based on C1 showed higher surface area
compared to the polymers based on C2. However, the polymers
2
-1
9
b
of microporosity. Considering the better porosity, we may
conclude that anhydrous AlCl is a much effective catalyst than
3
of FeCl -catalyzed did not follow this trend and C2 based
3
polymer showed ~20% higher specific surface area (Table 2),
4
| J. Name., 2012, 00, 1‐3
This journal is © The Royal Society of Chemistry 2012

Page 5 of 9
Journal Name
Journal of Materials Chemistry A
ARTICLE
3
which reflected the significant difference between AlCl and
Pore size distribution (PSD) for these polymers was
FeCl as catalyst in this case. These data further highlight the calculated using nonlocal density functional theoVryiew(ANrtiLclDe OFnTlin)e,
3
fact that the porous properties of the resulting polymers are indicating that these networks are filleDdOI:w10it.1h03a9/Cs4iTgAn0if5i3c4a9nDt
synthetically affected by the nature of monomers and catalyst.
fraction of micropore less than 10 Å in size (Fig. S5, ESI†).
2
-1
The highest BET surface area (1783 m ·g ) and pore Previous studies suggest that only pores less than 10 Å are
3
-1
volume (1.29 cm ·g ) were obtained for C1M3-Al. The results proved to be effective for H storage or CO capture at low
2
2
of our work can be comparable to or higher than that of other pressure since the kinetic diameters of H and CO are 2.9 and
2
2
9
b, 16, 19
HCPs produced by Friedel-Crafts alkylation (Table 3). The 3.3 Å, respectively.
Thus, an expected excellent
porosity in these polymers is controlled not only by the level of adsorption performance may be achieved for these materials,
cross-linking but also by subtle changes in the design of the which inspired us to further study the H and CO uptake
2
2
rigid monomer units.
abilities of these polymers.
Table 2 Synthetic condition, surface area and pore volume and gas sorption properties of this series.
c
d
CO
2
uptake
2
H uptake
a
b
Crosslinker
mmol
Monomer
mmol
SABET
m ·g
V
Total
3
V
cm ·g
Micro
2 2
CO /N
Selectivity
Materials
2
-1
-1
3
-1
Qst
kJ·mol
Qst
-1
e
-
1
-1
cm ·g
mg·g
mg·g
-
1
kJ·mol
C1M1-Al
C2M1-Al
C1M2-Al
C2M2-Al
C1M3-Al
C2M3-Al
C1M3-Fe
C2M3-Fe
C1 (0.5)
C2 (0.5)
C1 (0.5)
C2 (0.5)
C1 (0.5)
C2 (0.5)
C1 (0.5)
C2 (0.5)
Benzene (0.75)
Benzene (0.75)
Biphenyl (0.75)
Biphenyl (0.75)
TPB (0.5)
688
609
0.40
0.35
0.73
0.98
1.29
1.06
0.62
0.66
0.19
0.14
0.26
0.17
0.37
0.20
0.10
0.13
101
8.0
7.2
63.6
150
112
181
128
67.7
79.9
1164
1103
1783
1342
628
22.3
20.6
20.9
20.1
14.5
12.1
19.1
14.6
7.3
8.5
9.1
7.9
8.1
32.3
27.7
23.4
24.9
TPB (0.5)
TPB (0.5)
TPB (0.5)
755
9.0
a
b
c
d
e
Pore volume calculated from N
2
isotherm at P/P
0
= 0.95 and 77 K. Micropore volume calculated from t-Plot method. 273 K and 1 bar. 77 K and 1 bar.
IAST-predicted adsorption selectivities at 273 K and 1 bar using a 15:85 CO
2
:N
2
ratio.
knowledge, the adsorption capacities of C1M3-Al for CO
H is the highest in the HCPs under similar conditions reported
2
2
and
Table 3 Summary of the gas-uptake capacities of various HCPs for H
CO at low pressure.
2
and
2
so far (Table 3). These data prove that specific surface area,
molecular structure and chemical character of the resulting
porous polymers should be optimized in a synergistic way in
order to enhance the gas uptake capacity. In general, increased
gas uptake capacities were observed with increased surface
a
b
Cross-
linker
S
m g
BET
-1
H
2
uptake
mg g
CO
mg g
2
uptake
Monomer
2
-1
-1
Ref
this
work
14
c
TPB
C1
1783
19.1
181
d
e
TCT
FDA
913
-
180
159
f
13b
13c
area, i.e., CO
surface areas of these polymer networks when same cross
linker used: C1M3-Al C1M2-Al C1M1-Al. The CO and H
uptake properties of C1-based polymers are better than C2
2 2
and H uptakes at 1 bar follow the order of
TPB
FDA
FDA
1059
15.8
-
1
,1’-bi-2-
1015
-
174
>
>
2
2
naphthol
g
13a
13e
13b
20
-
fluorene
BCMBP
FDA
FDA
FDA
b
1700
1980
1391
1470
16.3
17.6
-
based polymers when the same monomer was used. For
h
TPE
160
135
130
example, C2M3-Al has lower H and CO uptake capacities
2
2
f
benzene
14.5
than C1M3-Al
.
i
TPM
-
(
a)180
(b)20
18
a
c
d
C1M3-Al
C1M2-Al
C1M1-Al
C2M3-Al
C2M2-Al
C2M1-Al
7
7 K and 1 bar. 273 K and 1 bar. TPB: 1,3,5-triphenylbenzene. TCT:
e f
160
2
,4,6-Tricarbazolo-1,3,5-triazine. FDA: formaldehyde dimethyl acetal. 1.13
16
g
h
140
14
bar. BCMBP: 4,4’-bis(chloromethyl)biphenyl. TPE: tetraphenylethylene.
1
20
00
i
12
TPM: tetraphenylmethane
1
1
0
8
6
4
2
0
80
60
40
2 2
A summary of the H and CO uptakes for the various
porous polymers are presented in Fig. 4. All samples show
significant H2 uptake even though their surface areas are
moderate, and no saturation was observed in the studied range
of pressures and temperatures, which indicates that higher H2
capacity can be achieved by increasing the pressure above 1
20
0
0
100
200
300
400
500
600
700
800
0
100
200
300
400
500
600
700
800
Pressure (mmHg)
Pressure (mmHg)
2
Fig. 4. Small gas adsorption of the samples at low pressure. (a) CO adsorption
isotherms at 273 K; (b) H adsorption isotherms at 77 K.
2
-
1
bar. The CO uptake of C1M3-Al is up to 181 mg·g at 1 bar
and 273 K, which is comparable to that of BILP-10 (177 mg g
2
2 2
Isosteric heat of adsorption of CO and H
-
1
21
-
To provide a further understanding of the binding affinity of the
)
)
,
,
OH functionalized porous organic frameworks (183 mg g
and other polymer networks. To the best of our
1
22
23
studied porous polymers toward CO , the isosteric heat of
2
This journal is © The Royal Society of Chemistry 2012
J. Name., 2012, 00, 1‐3 | 5

Journal of Materials Chemistry A
Page 6 of 9
Journal Name
ARTICLE
adsorption (Qst) was also calculated from the CO
2 2
isotherms investigate the gas selectivity of these networks. N adsorption
measured at 273, 283 and 293 K. The calculated Q values at experiments of four selected samples with high CO uptake
st
2
View Article Online
the initial adsorption stage for C1M2-Al
, C2M2-Al, C1M3-Al were carried out at 1 bar to examine the separation capability.
DOI: 10.1039/C4TA05349D
-
1
and C2M3-Al are on the scale of 20.1-22.3 kJ·mol (Table 1), The single-component gas sorption experiments were first
-
1 9b
which are comparable to other HCPs (20-24 kJ·mol ),
while lower than those The CO and N isotherms of all the tested samples show no
2 2
microporous polymers decorated with functional groups.
carried out on CO and N at 273 K and pressured up to 1 bar.
2 2
-
1 24
BLPs(20.2-28.3 kJ·mol ),
1
1c, 25
isotherm inflection and are fitting by the single-site Langmuir-
The values remain well below the energy of the chemical bond Freundlich equation to get equilibrium parameters, saturation
suggesting the polymers interact moderately with CO2 capacities and Langmuir constants. The CO /N selectivity was
2
2
molecules which is desirable for the regeneration of adsorbents. predicted using ideal adsorption solution theory (IAST), which
The isotherms exhibit relatively steep initial uptakes at low has frequently been used to predict the behaviour of mixed
pressures which indicates a strong affinity towards H gas. The component isotherms based on single component isotherms.
2
H2 Qst values were also calculated from the H2 isotherms The IAST calculations were carried out for binary mixture
measured at 77 K and 87 K (Table 1, Fig. 5). At the onset of containing 15% CO and 85% N in the typical flue gases, and
2
2
-
1
adsorption, the H Q values are 8.5, 9.1, 7.9 and 8.1 kJ·mol
the results are shown in Fig. 6 and the selectivities of the
polymers for CO /N at 1 bar and 273 K was given in Table 1.
2
st
for C1M2-Al
,
C2M2-Al
,
C1M3-Al and C2M3-Al,
2
2
respectively, which are higher than other organic polymers such As shown in Fig. 6, the CO /N selectivities of the four samples
2
2
-
1 11a
as porous polymer networks (PPNs, 5.5-7.6 kJ·mol ),
at 273 K decrease slowly as pressure increase. It is interesting
-
1 26
polyimide networks (5.3-7.0 kJ mol ) and nitrogen rich that the C1M2-Al in the four samples shows the highest
-
1 27
porous aromatic frameworks (NPAF, 5.2 kJ mol ). The H Q
CO /N selectivity (32.3 at 1 bar and 273 K), which is higher
2 2
2
st
2
8
29
30
of the polymers based on C2 are higher than that of the than PPFs (14.5-20.4), FCTF-1 (31) and NPOF-4 (12), but
polymers based on C1 when same monomer used, which lower than those functionalized porous organic frameworks.
indicates that the introduction of methyl group narrow the pores
and thus strengthen the interaction between H and polymers.
1
1c,
3
1
In our case, the high BET surface area has not led to the high
CO /N selectivity, which indicates that CO /N selectivity is
2
2
2
2
2
influenced by a combination of factors of pore structure. An
ideal adsorbent should be capable of adsorbing a large amount
of CO2 with a high CO /N selectivity at low CO2 partial
(
a)25
(b)10
20
15
10
5
0
2
2
8
6
4
2
C1M2-Al
C1M3-Al
C2M2-Al
C2M3-Al
pressures (< 0.2 bar). Among these polymers, C1M2-Al is the
good candidate for the balanced CO2 uptake capacity and
CO /N selectivity.
2
2
Conclusions
0
20
40
60
80
100
120
140
0
2
4
6
8
10
12
-1
)
-1
CO2 Adsorbed (mg g
H2 Adsorbed (mg g
)
We have successfully synthesized a series of porous polymer
frameworks with two different tritopic benzyl bromide cross-
linkers and different aromatic monomers through the
Friedel−Crafts alkylation. The catalyst effect for the pore
structure has been re-evaluated. A comparative study of gas
2 2
Fig. 5 Plots of the isosteric heat of adsorption (Qst) for CO and H
uptake ability shows that the anhydrous AlCl is a much more
3
effective Lewis acid catalyst than anhydrous FeCl and is more
3
beneficial in terms of porosity and gas sorption. The BET
2
−1
surface area of these polymers is up to 1783 m g . As
expected, these polymers exhibit exceptionally high H uptake
2
-
1
of up to 19.1 mg·g (77 K and 1 bar), and high CO uptake of
81 mg·g (273 K and 1 bar), which are among the highest
2
-
1
1
reported values for HCPs under the same conditions. These
polymers also exhibit excellent CO sorption selectivity, the
2
best CO /N (15/85) selectivity calculated by IAST at 273 K
2
2
and 1 bar is up to 32.3 for C1M2-Al. In our case, the gas
sorption properties depend on the nature of the cross-linker
Fig. 6 IAST selectivities of CO
composition at 273 K
2
over N
2
for binary gas mixtures of 15/85 molar used. Due to the inexpensive starting material, the preparative
strategy exhibits cost-effective advantages and these porous
polymers are promising candidates for energy applications on a
larger scale.
Gas selectivity studies
The above results indicate that these porous polymers possess
Acknowledgements
the excellent CO uptake abilities, which motivate us to further
2
6
| J. Name., 2012, 00, 1‐3
This journal is © The Royal Society of Chemistry 2012

Page 7 of 9
Journal Name
Journal of Materials Chemistry A
ARTICLE
This work was supported by the NSFC (Grants 21271172 and
T. Li and B. Tan, J. Mater. Chem.
A
,
2014, DOI:
2
1131006), the “One Hundred Talent Project” from Chinese
10.1039/c4ta05265j.
View Article Online
DOI: 10.1039/C4TA05349D
Academy of Sciences, and the NSF of Fujian Province (Grant 10. (a) P. Kuhn, M. Antonietti and A. Thomas, Angew. Chem. Int. Ed.
,
2
012J01058)
47, 3450; (b) M. J. Bojdys, J. Jeromenok, A. Thomas and M.
2
008,
Antonietti, Adv. Mater., 2010, 22, 2202; (c) M. X. Tan, Y. Zhang and
J. Y. Ying, ChemSusChem, 2013, , 1186.
Notes and references
State Key Laboratory of Structural Chemistry, Fujian Institute of
6
a
1
1. (a) W. Lu, D. Yuan, D. Zhao, C. I. Schilling, O. Plietzsch, T. Muller,
S. Bräse, J. Guenther, J. Blümel, R. Krishna, Z. Li and H.-C. Zhou,
Chem. Mater., 2010, 22, 5964; (b) D. Yuan, W. Lu, D. Zhao and H.
C. Zhou, Adv. Mater., 2011, 23, 3723; (c) W. Lu, D. Yuan, J. Sculley,
Research on the Structure of Matter, Chinese Academy of Sciences,
Fuzhou, Fujian 350002 (P. R. China). E-mail: ydq@fjirsm.ac.cn
b
University of Chinese Academy of Sciences, Beijing 100049 (P. R.
China).
D. Zhao, R. Krishna and H.-C. Zhou, J. Am. Chem. Soc., 2011, 133
8126.
2. (a) T. Ben, H. Ren, S. Ma, D. Cao, J. Lan, X. Jing, W. Wang, J. Xu,
F. Deng, J. M. Simmons, S. Qiu and G. Zhu, Angew. Chem. Int. Ed.
009, 48, 9457; (b) C. Zhang, L.-H. Peng, B. Li, Y. Liu, P.-C. Zhu,
Z. Wang, D.-H. Zhan, B. Tan, X.-L. Yang and H.-B. Xu, Polym.
Chem., 2013, , 3663.
3. (a) M. G. Schwab, A. Lennert, J. Pahnke, G. Jonschker, M. Koch, I.
Senkovska, M. Rehahn and S. Kaskel, J. Mater. Chem., 2011, 21
131; (b) B. Li, R. Gong, W. Wang, X. Huang, W. Zhang, H. Li, C.
,
†
Electronic Supplementary Information (ESI) available: Synthesis and
1
Characterization data. See DOI: 10.1039/b000000x/
1
1
1
.
(a) K. Sumida, D. L. Rogow, J. A. Mason, T. M. McDonald, E. D.
Bloch, Z. R. Herm, T. H. Bae and J. R. Long, Chem. Rev., 2012, 112
24; (b) Z. Chang, D. S. Zhang, Q. Chen and X. H. Bu, Phys. Chem.
Chem. Phys., 2013, 15, 5430; (c) S. Xu, Y. Luo and B. Tan,
Macromol. Rapid Commun. 2013, 34 471; (d) S. Enthaler,
ChemSusChem, 2008, , 801; (e) K. M. Yu, I. Curcic, J. Gabriel and
S. C. Tsang, ChemSusChem, 2008, , 893.
,
,
2
7
4
,
,
1
,
1
2
2
3
4
.
.
.
(a) G. T. Rochelle, Science, 2009, 325, 1652; (b) N. MacDowell, N.
Florin, A. Buchard, J. Hallett, A. Galindo, G. Jackson, C. S. Adjiman,
C. K. Williams, N. Shah and P. Fennell, Energy Environ. Sci., 2010,
Hu and B. Tan, Macromolecules, 2011, 44, 2410; (c) R. Dawson, L.
A. Stevens, T. C. Drage, C. E. Snape, M. W. Smith, D. J. Adams and
A. I. Cooper, J. Am. Chem. Soc., 2012, 134, 10741; (d) X. F. Jing, D.
3
, 1645; (c) D. M. D'Alessandro, B. Smit and J. R. Long, Angew.
L. Zou, P. Cui, H. Ren and G. S. Zhu, J. Mater. Chem. A, 2013, 1,
Chem. Int. Ed., 2010, 49, 6058.
1
3926; (e) S. W. Yao, X. Yang, M. Yu, Y. H. Zhang and J. X. Jiang,
(a) S. Choi, J. H. Drese and C. W. Jones, ChemSusChem, 2009,
2
,
J. Mater. Chem. A, 2014, 2, 8054; (f) J. Y. Lee, C. D. Wood, D.
7
96; (b) A. Goeppert, H. Zhang, M. Czaun, R. B. May, G. K.
Bradshaw, M. J. Rosseinsky and A. I. Cooper, Chem. Commun.
006, 2670; (g) M. G. Schwab, I. Senkovska, M. Rose, N. Klein, M.
Koch, J. Pahnke, G. Jonschker, B. Schmitz, M. Hirscher and S.
Kaskel, Soft Matter, 2009, , 1055; (h) J.-H. Ahn, J.-E. Jang, C.-G.
Oh, S.-K. Ihm, J. Cortez and D. C. Sherrington, Macromolecules
006, 39, 627; (i) R. Dawson, T. Ratvijitvech, M. Corker, A.
Laybourn, Y. Z. Khimyak, A. I. Cooper and D. J. Adams, Polym.
Chem., 2012, , 2034.
,
Prakash, G. A. Olah and S. R. Narayanan, ChemSusChem, 2014,
7
,
2
1
386; (c) Y. Hu, W. M. Verdegaal, S. H. Yu and H. L. Jiang,
ChemSusChem, 2014, , 734.
(a) R. Dawson, A. I. Cooper and D. J. Adams, Prog. Polym. Sci.
7
5
,
,
,
2
2
012, 37, 530; (b) J.-X. Jiang and A. I. Cooper, Top. Curr. Chem.
010, 293, 1.
2
5
6
.
.
Y. L. Luo, S. C. Zhang, Y. X. Ma, W. Wang and B. Tan, Polym.
Chem., 2013, , 1126.
3
4
1
1
4. X. Zhu, S. M. Mahurin, S. H. An, C. L. Do-Thanh, C. Tian, Y. Li, L.
W. Gill, E. W. Hagaman, Z. Bian, J. H. Zhou, J. Hu, H. Liu and S.
Dai, Chem. Commun., 2014, 50, 7933.
(a) N. B. McKeown, P. M. Budd, K. J. Msayib, B. S. Ghanem, H. J.
Kingston, C. E. Tattershall, S. Makhseed, K. J. Reynolds and D.
Fritsch, Chem. Eur. J., 2005, 11, 2610; (b) N. B. McKeown, B.
Gahnem, K. J. Msayib, P. M. Budd, C. E. Tattershall, K. Mahmood,
S. Tan, D. Book, H. W. Langmi and A. Walton, Angew. Chem. Int.
Ed., 2006, 45, 1804; (c) B. S. Ghanem, K. J. Msayib, N. B.
McKeown, K. D. Harris, Z. Pan, P. M. Budd, A. Butler, J. Selbie, D.
Book and A. Walton, Chem. Commun., 2007, 67.
5. (a) C. A. Ilioudis, D. A. Tocher and J. W. Steed, J. Am. Chem. Soc.
004, 126, 12395; (b) A. W. van der Made and R. H. van der Made,
J. Org. Chem., 1993, 58, 1262.
6. Y. Liu, S. Wu, G. Wang, G. Yu, J. Guan, C. Pan and Z. Wang, J.
Mater. Chem. A, 2014, , 7795.
,
2
1
1
2
7. (a) W. Chaikittisilp, M. Kubo, T. Moteki, A. Sugawara-Narutaki, A.
7
8
.
.
J. X. Jiang, F. Su, A. Trewin, C. D. Wood, N. L. Campbell, H. Niu,
C. Dickinson, A. Y. Ganin, M. J. Rosseinsky, Y. Z. Khimyak and A.
I. Cooper, Angew. Chem. Int. Ed., 2007, 46, 8574.
Shimojima and T. Okubo, J. Am. Chem. Soc., 2011, 133, 13832; (b)
M. B. Smith and J. March, in March's Advanced Organic Chemistry
John Wiley & Sons, Inc., 2006, 729.
,
,
,
(a) H. M. El-Kaderi, J. R. Hunt, J. L. Mendoza-Cortes, A. P. Cote, R.
E. Taylor, M. O'Keeffe and O. M. Yaghi, Science, 2007, 316, 268;
1
1
2
2
2
8. J. Weber, M. Antonietti and A. Thomas, Macromolecules, 2008, 41
2
880.
9. J. A.-M. D. Cazorla-Amorós, and A. Linares-Solano, Langmuir
996, 12, 2820.
0. R. Dawson, E. Stöckel, J. R. Holst, D. J. Adams and A. I. Cooper,
Energy Environ. Sci., 2011, , 4239.
(
b) F. J. Uribe-Romo, C. J. Doonan, H. Furukawa, K. Oisaki and O.
M. Yaghi, J. Am. Chem. Soc., 2011, 133, 11478.
1
9
.
(a) C. D. Wood, B. Tan, A. Trewin, H. Niu, D. Bradshaw, M. J.
Rosseinsky, Y. Z. Khimyak, N. L. Campbell, R. Kirk, E. Stockel and
A. I. Cooper, Chem. Mater., 2007, 19, 2034; (b) C. F. Martín, E.
Stöckel, R. Clowes, D. J. Adams, A. I. Cooper, J. J. Pis, F. Rubiera
and C. Pevida, J. Mater. Chem., 2011, 21, 5475; (c) S. Xu, K. Song,
4
1. M. G. Rabbani, A. K. Sekizkardes, O. M. El-Kadri, B. R. Kaafarani
and H. M. El-Kaderi, J. Mater. Chem., 2012, 22, 25409.
2. A. P. Katsoulidis and M. G. Kanatzidis, Chem. Mater., 2011, 23
818.
,
1
This journal is © The Royal Society of Chemistry 2012
J. Name., 2012, 00, 1‐3 | 7

Journal of Materials Chemistry A
Page 8 of 9
Journal Name
ARTICLE
2
3. (a) G. Li and Z. Wang, Macromolecules, 2013, 46, 3058; (b) S. Wu,
S. Gu, A.-Q. Zhang, G. Yu, Z. Wang, c. Pan and X. Jian, J. Mater.
Chem. A, 2014, DOI: 10.1039/c4ta04734f.
View Article Online
DOI: 10.1039/C4TA05349D
2
4. (a) K. T. Jackson, M. G. Rabbani, T. E. Reich and H. M. El-Kaderi,
Polym. Chem., 2011,
Jackson, P. Jena and H. M. El-Kaderi, J. Mater. Chem., 2012, 22
3524.
5. R. Dawson, D. J. Adams and A. I. Cooper, Chem. Sci., 2011, 2, 1173.
2, 2775; (b) T. E. Reich, S. Behera, K. T.
,
1
2
2
6. Z. Wang, B. Zhang, H. Yu, L. Sun, C. Jiao and W. Liu, Chem.
Commun., 2010, 46, 7730.
2
7. D. E. Demirocak, M. K. Ram, S. S. Srinivasan, D. Y. Goswami and
E. K. Stefanakos, J. Mater. Chem. A, 2013, 1, 13800.
2
2
8. Y. Zhu, H. Long and W. Zhang, Chem. Mater., 2013, 25, 1630.
9. Y. Zhao, K. X. Yao, B. Teng, T. Zhang and Y. Han, Energy Environ.
Sci., 2013,
0. T. İslamoğlu, M. Gulam Rabbani and H. M. El-Kaderi, J. Mater.
Chem. A, 2013, , 10259.
6, 3684.
3
3
1
1. (a) W. Lu, J. P. Sculley, D. Yuan, R. Krishna, Z. Wei and H.-C.
Zhou, Angew. Chem. Int. Ed., 2012, 51, 7480; (b) Z. Qiao, Z. Wang,
S. Zhao, S. Yuan, J. Wang and S. Wang, RSC Adv., 2013,
H. A. Patel, S. Hyun Je, J. Park, D. P. Chen, Y. Jung, C. T. Yavuz
and A. Coskun, Nat. Commun., 2013, , 1357.
3, 50; (c)
4
8
| J. Name., 2012, 00, 1‐3
This journal is © The Royal Society of Chemistry 2012

Page 9 of 9
Journal of Materials Chemistry A
View Article Online
DOI: 10.1039/C4TA05349D
TOC
A facile synthesis of microporous organic polymers for
efficient gas storage and separation
a,b
a,b
a
a
*,a
Guoliang Liu, Yangxin Wang, Chaojun Shen, Zhanfeng Ju and Daqiang Yuan
A series of porous polymers based on tritopic benzyl bromide exhibit high H and CO uptake
2
2
capacities and CO /N selectivities.
2
2