Enhancement of Catalytic Activity in Epoxide Hydration by Increasing the Concentration of Cobalt(III)/Salen in Porous Polymer Catalysts

Article abstract of DOI:10.1002/cctc.201501222

The rational design of catalytic materials from the reaction characteristics is expected to be a useful strategy to create highly efficient catalysts. Herein, according to a well-established reaction pathway of epoxide hydration catalyzed a dual-molecular system of Co³⁺/salen in which a high concentration of active sites is favorable to enhance the activity, we provide an alternative way to prepare a highly efficient heterogeneous catalyst with a high concentration of Co³⁺/salen from the polymerization of vinyl-functionalized salen monomers followed by the loading of Co³⁺ species (Co³⁺/POL-salen). Co³⁺/POL-salen has a hierarchical porosity and an extraordinary hydrothermal stability. Importantly, catalytic tests in epoxide hydration demonstrate that Co³⁺/POL-salen affords excellent high activities, which are even better than those of the homogeneous version. This phenomenon is related to the very high concentration of Co³⁺/salen in the catalyst. In addition, this catalyst can be recycled readily because of its excellent hydrothermal stability.

Full text of DOI:10.1002/cctc.201501222

DOI: 10.1002/cctc.201501222
Full Papers
Enhancement of Catalytic Activity in Epoxide Hydration by
Increasing the Concentration of Cobalt(III)/Salen in Porous
Polymer Catalysts
[
a]
[a, b]
[a]
[a]
[a]
[a]
Zhifeng Dai, Qi Sun,
Fang Chen, Shuxiang Pan, Liang Wang, Xiangju Meng,*
[b]
[a]
Jixue Li, and Feng-Shou Xiao*
3
+
3+
3+
The rational design of catalytic materials from the reaction
characteristics is expected to be a useful strategy to create
highly efficient catalysts. Herein, according to a well-estab-
lished reaction pathway of epoxide hydration catalyzed a dual-
the loading of Co species (Co /POL-salen). Co /POL-salen
has a hierarchical porosity and an extraordinary hydrothermal
stability. Importantly, catalytic tests in epoxide hydration dem-
3
+
onstrate that Co /POL-salen affords excellent high activities,
which are even better than those of the homogeneous version.
This phenomenon is related to the very high concentration of
3
+
molecular system of Co /salen in which a high concentration
of active sites is favorable to enhance the activity, we provide
an alternative way to prepare a highly efficient heterogeneous
3+
Co /salen in the catalyst. In addition, this catalyst can be recy-
cled readily because of its excellent hydrothermal stability.
3
+
catalyst with a high concentration of Co /salen from the poly-
merization of vinyl-functionalized salen monomers followed by
Introduction
[
25–27]
The design of catalytic materials from reaction characteristics is
the relatively low hydrothermal stability of MOFs
and or-
[
1–7]
[28,29]
of great help for the preparation of efficient catalysts.
The
dered mesoporous silica materials
still represents a limita-
cooperative activation of reagents by two or more catalytically
active sites is recognized to be a common feature in organic
tion for long-term practical applications, in particular to the
presence of water as a reactant. Therefore, it is strongly desira-
ble to search for hydrothermally stable heterogeneous cata-
[
8–14]
transformations.
Typically, epoxide hydration catalyzed by
3+
3+
Co /salen complex involves the dual activation of the epoxide
lysts with a high Co /salen concentration.
3
+
and water, respectively, and a high concentration of Co /salen
Porous organic polymers (POPs) are an emerging class of
porous materials that have attracted much attention because
[15–18]
is favorable for the enhancement of activities.
Notably,
3+
soluble Co /salen complexes are dispersed homogeneously in
of their excellent hydrothermal and chemical stability, designa-
3+
[30–46]
the catalytic system, and the concentration of Co /salen spe-
ble pore walls, and high surface areas.
If the POPs are con-
3
+
cies is low. In contrast, insoluble Co /salen catalysts are ex-
pected to provide a promising platform to create a confined
structed by salen-functionalized ligand themselves, the resul-
tant materials should have an extremely high concentration of
[
19–21]
[47–50]
3+
space in which the active species could be enriched.
For
salen moieties.
After the introduction of Co species,
[
22]
[23,24]
3+
3+
example, Cui et al. and Yang et al.
designed Co /salen
a very high density of Co /salen species could be obtained in
the sample.
species in metal–organic frameworks (MOFs) and ordered mes-
oporous silica materials rationally, respectively. These insoluble
In this contribution, to demonstrate the “proof-of-concept”,
a hierarchically porous salen-functionalized polymer (POL-
salen) was fabricated successfully from the polymerization of
vinyl-functionalized salen monomers. POL-salen has an extraor-
dinary hydrothermal stability, hierarchical porosity, large sur-
face areas, flexible frameworks, and a high concentration of
3+
catalysts have high concentrations of Co /salen species in the
confined space and show superior catalytic performances in
the hydration of epoxides. Despite this encouraging progress,
[
a] Z. Dai, Dr. Q. Sun, Dr. F. Chen, S. Pan, Dr. L. Wang, Dr. X. Meng,
Prof. F.-S. Xiao
À1
salen species (1.56 mmolg ). After metalation with Co species,
3+
Key Laboratory of Applied Chemistry of Zhejiang Province
and Department of Chemistry
Zhejiang University
Hangzhou, Zhejiang, 310028 (P.R. China)
E-mail: mengxj@zju.edu.cn
the obtained Co /POL-salen heterogeneous catalyst exhibits
high activities in the hydration of epoxides to monoalkylene
glycols under mild reaction conditions and outperforms the
homogeneous counterpart. The superior catalytic performance
of the catalyst is strongly related to the high concentration of
fsxiao@zju.edu.cn
3+
3+
[
b] Dr. Q. Sun, Prof. J. Li
Co /salen in the confined pores of the Co /POL-salen cata-
lyst, which promotes the cooperative activation of water and
epoxide.
Electron Microscopy Centre
Zhejiang University
Hangzhou, Zhejiang, 310028 (P.R. China)
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/cctc.201501222.
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1
3
salen. The C magic-angle spinning (MAS) NMR spectrum of
POL-salen (Figure 1C) shows a peak at d=40.3 ppm assigned
to the polymerized vinyl groups in addition to the peaks attrib-
uted to the characteristic structure of the salen ligand (Fig-
Results and Discussion
3
+
Synthesis and characterization of Co /POL-salen
[
47]
POL-salen was synthesized from the polymerization of vinyl-
functionalized salen monomer (Scheme 1, Scheme S1) in the
presence of 1-methyl-2-pyrrolidinone (NMP) solvent at 1008C
for 24 h. After washing with CH Cl and drying at 508C under
ure S2). These results suggest that the structure of the salen
ligand is well maintained during the polymerization process.
N sorption isotherms of POL-salen collected at À1968C show
2
a steep step at P/P <0.01 and a hysteresis loop at 0.1<P/P <
2
2
0
0
vacuum, a yellow solid (POL-salen) in a higher than 99.0%
yield was obtained.
0.98 with a sharp N uptake at a high relative pressure (Fig-
2
ure 1D), which suggests the coexistence of micro-, meso-, and
[
51,52]
The morphology of the POL-salen was examined by SEM
and TEM (Figure 1A and B). POL-salen displays rather rough
surfaces and appears as aggregates of much smaller particles
on the order of tens of nanometers in size. The powder X-ray
diffraction (PXRD) pattern (Figure S1) shows a very broad peak
at 2q=10–308, which indicates the amorphous nature of POL-
macroporsity in the framework.
Correspondingly, pore
sizes of the sample are mainly distributed at 0.65–1.5, 2.7–50,
and over 50 nm (Figure S3), as calculated by the nonlocal den-
sity functional theory method (NLDFT). The BET surface area
and total pore volume of POL-salen are estimated at
2
À1
3
À1
540 m g and 0.74 cm g , respectively. The hieratical porosi-
ty is expected to improve the efficiency of transport processes
[
53–55]
as well as the accessibility of active sites.
3+
The introduction of Co species into POL-salen was per-
formed by the treatment of POL-salen with Co(OAc) ·4H O in
2
2
a mixed solvent of CH Cl and MeOH under a N atmosphere
2
2
2
2+
to obtain Co /POL-salen that was followed by the oxidation
of the metaled POL-salen in open air in the presence of acetic
3
+
acid to obtain Co /POL-salen. The Co species only exist as mo-
lecular species coordinated to salen and do not form aggre-
gates or nanoparticles because of the presence of a large
amount of acetic acid and air, which is also supported by TEM
2+
(
Figure S5). In addition, compared with POL-salen, Co /POL-
salen shows a new peak at approximately l=430 nm in the
2+
UV/Vis spectrum, which can be assigned to d–p* of the Co /
salen complex. After oxidation, the resultant sample gives
Scheme 1. Synthesis of POL-salen polymer from the vinyl-functionalized
salen monomer.
3+
peaks at l=411 and 692 nm, which are characteristic of Co /
13
Figure 1. A) SEM image, B) TEM image, C) C MAS NMR spectrum, and D) N
2
sorption isotherms of POL-salen.
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[
54]
salen species (Figure S6). Similar changes were also observed
tant raw materials for the manufacture of polyester resins, anti-
3+
[57,58]
in homogeneous Co /salen, developed by Jacobsen et al.
freezes, cosmetics, and medicines.
Currently, the biggest
[
15]
(
Scheme S2, Figure S7).
These results confirm that the Co
challenge encountered in industry is that a large excess of
water (10–25 moles of water per mole of alkylene oxide) is re-
quired to realize a high selectivity of monoalkylene glycol by
suppressing the side reactions of unreacted epoxides with the
formed monoalkylene glycol. As a result, a large amount of
water has to be distilled to enable the recovery of the monoal-
kylene glycols from the reaction mixture, which in turn in-
volves the consumption of a huge amount of energy. This pro-
species in POL-salen is in the 3+ oxidation state. In addition,
the color of POL-salen changed from yellow to dark red after
2+
the introduction of Co species and then became dark brown
after oxidation. These color changes are associated with the
2+
3+
characteristic colors of Co /salen and Co /salen species in
[56]
good agreement with those reported previously. These re-
3
+
sults demonstrate that Co species are coordinated success-
fully with salen ligands in POL-salen. Inductively coupled
plasma optical emission spectroscopy (ICP-OES) revealed a Co
[
59–63]
3+
cess is environmentally unfriendly.
Co /salen-catalyzed
epoxide hydration is considered to be a promising alternative
route toward monoalkylene glycols because it could be operat-
ed at a relatively low molar ratio of water to alkylene oxide (as
low as 2.0) and mild reaction temperatures (such as room tem-
perature). Nevertheless, for practical applications, heterogene-
ous catalysis is more attractive because of the simple and com-
À1
À1
loading of 68.4 mgg (1.16 mmolg ), which suggests that
88% of the salen ligands in POL-salen were coordinated with
ꢀ
3+
Co species. Notably, the Co /POL-salen catalyst still possesses
2
À1
a BET surface area of 512 m g and a total pore volume of
3
À1
0
.58 cm g (Figure 2A). Excitingly, even after hydrothermal
3+
[64–68]
treatment for 48 h at 1008C, Co /POL-salen maintained its sur-
plete separation of the product from the catalyst.
2
À1
3+
face area (519 m g ; Figure 2B, Figure S8). However, the
uptake at a high relative pressure is reduced, which might be
related to the partial aggregation of the polymer. ICP analysis
of the sample shows that the Co species in the catalyst are
stable during the hydrothermal treatment because Co species
are undetectable (<10 ppb) in the filtrate. This catalyst feature
is very helpful for their long-term application in the hydration
of epoxides.
The potential of the Co /POL-salen catalyst for epoxide hy-
dration was evaluated using propylene oxide (PO) as a model
substrate. Hydration reactions were performed at room tem-
perature with a molar ratio of H O/PO of 2:1 and 0.2 mol% of
2
catalyst based on Co species. Catalytic data for the hydration
of PO over various catalysts are presented in Table 1. Notably,
[a]
Table 1. Hydration of PO over various catalysts.
Entry
1
Catalyst
Conversion [%]
Selectivity [%]
3
+
Co /POL-salen
H-ZSM-5
98.1
2.3
5.6
42.1
86.2
91.6
71.5
89.5
97.6
>99.0
87.9
75.3
[b]
2
3
4
5
6
7
8
9
Amberlyst-15
H
2
SO
4
76.1
3
+
Co /salen
Co /POL-salen
Co /salen
Co /POL-salen
>99.0
>99.0
>99.0
>99.0
>99.0
[
[
[
[
c]
c]
d]
e]
3+
3+
3+
3+
Co /POL-salen
[
a] Reaction conditions: PO (0.725 g, 12.5 mmol), H
2
O (0.45 g, 25 mmol),
catalyst (0.2 mol% based on Co species), S/C=500, RT, 10 h; [b] 0.1 g cat-
alyst was used, Si/Al=20; [c] catalyst (0.05 mol%), S/C=2000, 40 h; [d] re-
3
+
cycled five times of Co /POL-salen catalyst (0.05 mol%, S/C=2000);
e] after treatment in boiling water for 48 h and regenerated similarly to
that in the recycling tests.
[
3+
Co /POL-salen gives a conversion of PO as high as 98.1% with
a selectivity for 1,2-propanediol of over 99.0% (entry 1 in
Table 1). This activity and selectivity are even comparable with
3+
those of the heterogeneous catalyst with high Co /salen con-
centration in the mesocages of FDU-12, one of the best heter-
[
22–24]
ogeneous catalysts for epoxide hydration.
In contrast, con-
3
+
ventional solid acid catalysts H-ZSM-5 and Amberlyst-15 afford
very low activities (2.3 and 5.6%, entries 2 and 3 in Table 1);
the conventional liquid acid catalyst of H SO shows a PO con-
2
Figure 2. N sorption isotherms of Co /POL-salen a) before and b) after
treatment in boiling water for 48 h.
2
4
version of 42.1% and 1,2-propanediol selectivity of 76.1%
entry 4 in Table 1).
In particular, the heterogeneous Co /POL-salen catalyst is
Evaluation of catalytic performance
(
3
+
The production of monoalkylene glycols from the hydration of
epoxides has received much attention because they are impor-
3
+
more active than the homogeneous Co /salen catalyst (con-
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version of 98.1 vs. 86.2%, entries 1 and 5 in Table 1). The differ-
dration of PO, and the catalytic activities demonstrated that
the PO conversion increases almost linearly with the mass frac-
tion of salen ligand in the polymer catalysts (Figure 4). As the
textural parameters, such as surface area, are very similar and
active sites are the same in these catalysts (Figure S10,
Table S2), the major difference in them is the continuity of the
active sites in the polymer catalysts with various amounts of
DVB molecules. Presumably, the continuity of the active sites
might affect their local concentration. Therefore, it is reasona-
ble to propose that a high local concentration of the active
3+
ences in terms of the activity between Co /POL-salen and
3+
Co /salen become greater as the catalyst amount decreases in
the catalytic system. For example, if the catalyst amount is re-
3
+
duced to 0.05 mol%, Co /POL-salen still gives a PO conversion
3+
of 91.6%, whereas the soluble Co /salen complex affords
a conversion of only 71.5% (Figure S9, entries 6 and 7 in
Table 1).
Generally, homogeneous catalysts exhibit higher catalytic ac-
tivities than the corresponding heterogeneous catalysts be-
cause the active sites in the homogeneous catalysts are fully
accessible to the reactants. However, here the catalytic tests
3+
sites in the Co /POL-salen catalyst is indeed an important
factor to maximize the cooperative activation of water and ep-
3+
3+
show that the heterogeneous Co /POL-salen catalyst has
a much better catalytic performance than the homogeneous
version with the same number of active sites, which should be
oxide species over Co /salen species, which is further support-
ed by the kinetic tests (Figure S11) and is consistent previous
[
8–14]
studies.
3
+
related directly to the unique features of Co /POL-salen, such
3+
as the porosity and high concentration of Co /salen. It has
3+
been reported that the proposed mechanism of the Co /
salen-catalyzed hydration of epoxides was through a dual-mo-
3+
lecular (Co /salen) cooperative activation pathway (Figure 3).
3
+
Figure 4. Influence of the mass fraction of salen in the polymer (Co /PDVB-
x-salen, x=1 stands for Co /POL-salen) on the catalytic performance (the
3
+
/
3+
Figure 3. Proposed cooperative activation reaction pathway on dual Co
salen species.
selectivity of the reaction is high than 99.0%). Reaction conditions: PO
2
(25 mmol), H O (50 mmol), RT, substrate to catalyst ratio of 2000, 40 h.
3
+
In this case, the high concentration of Co /salen is favorable
3
+
for the cooperative activation of dual Co /salen groups. For
The stability of the catalytic system is of great importance
3+
3+
3+
the Co /POL-salen catalyst, densely populated Co /salen spe-
cies benefit their synergistic cooperation in catalysis. As
a result, the rate of the formation of product is improved sig-
for practical applications. To evaluate the recyclability, Co /
POL-salen was recovered after each reaction by simple centri-
fugation and regenerated under aerobic and acidic conditions.
The catalytic activity and selectivity were well maintained to
give a PO conversion of 89.5% (fresh catalyst affords a conver-
sion of 91.6%) with a selectivity of 1,2-propanediol above
99.0% after five cycles (Table S3), which demonstrates the ex-
3+
nificantly. In comparison, the Co species in the homogeneous
catalytic system is highly separated, and the interaction be-
3+
tween the water and epoxide activated by the Co /salen spe-
cies is relatively difficult. Notably, if the ratio of substrate to
catalyst (S/C) is increased, the concentration of active sites in
3+
cellent recyclability of the Co /POL-salen catalyst. In addition,
after hydrothermal treatment in boiling water for 48 h, the
sample still shows a high conversion (97.6%) and excellent se-
lectivity (>99%, entry 9 in Table 1). These results indicate the
excellent hydrothermal stability of the catalyst, which is very
helpful for its industrial application.
3+
the homogeneous Co /salen system is further diluted, in con-
3+
3+
trast, for Co /POL-salen, the Co species only confined in the
3+
catalyst and the local density of Co species in the catalyst re-
mains almost the same regardless of the change in the S/C
ratio. Consequently, the heterogeneous catalyst shows a much
higher activity than the homogeneous counterpart, especially
at a high S/C ratio.
Similarly, epichlorohydrin, 1,2-epoxyhexane, and 1,2-epoxy-
ethylbenzene were employed as the substrate for epoxide hy-
3+
To further access the importance of the local concentration
dration over Co /POL-salen. Interestingly, the heterogeneous
3
+
3+
of active species in the Co /POL-salen catalyst, we have syn-
thesized a series of catalysts with an adjustable concentration
Co /POL-salen catalyst still exhibits a much higher activity
3+
than the homogeneous Co /salen catalyst (Figure 5, Table S4).
3+
3+
of Co /salen species by the copolymerization of vinyl-func-
tionalized salen monomers with divinybenzene (DVB) at vari-
ous mass ratios (PDVB-x-salen, x is the mass fraction of salen in
the polymer). After the metalation of PDVB-x-salen polymers
These results confirm the high efficiency of the Co /POL-salen
catalyst for epoxide hydration.
3+
with Co species, the resultant catalysts were tested in the hy-
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2+
Synthesis of Co /POL-salen
2+
Co /POL-salen was synthesized by the addition of a solution of
Co(OAc) ·4H O (0.22 g) in MeOH (20 mL) to POL-salen (0.5 g),
2
2
which was preswelled in CH Cl (20 mL) with stirring under N at
2
2
2
RT. After 12 h, the polymer was collected by filtration, rinsed se-
quentially with MeOH and CH Cl , and then dried under vacuum to
2
2
yield the product as a dark red powder.
3+
Synthesis of Co /POL-salen
2+
Co /POL-salen (0.5 g) was added to a 9:1 PhMe/AcOH solution
(20 mL). The mixture was stirred in air at RT for 3 h. The polymer
was collected by filtration, rinsed with CH Cl , and dried under
3
+
Figure 5. Catalytic performance of Co /POL-salen (orange) and homogene-
3+
ous Co /salen (green) for the hydration of various epoxides. Reaction condi-
tions: epoxide (12.5 mmol), H O (25 mmol), 408C for A) epichlorohydrin, S/
C=500, 8 h, B) 1,2-epoxyhexane, S/C=500, 16 h, and C) 1,2-epoxyethyl-
benzene, S/C=250, 60 h.
2
2
2
vacuum to yield the product as a dark brown powder.
Procedure for the hydration of epoxides
Conclusions
3
+
Typically, Co /POL-salen (10.8 mg) was added into a 10 mL glass
tube followed by the addition of PO (1.45 g, 25 mmol) and water
We have demonstrated a successful rational design of a highly
efficient heterogeneous catalyst based on the reaction mecha-
(
0.9 g, 50 mmol). After the mixture was stirred at RT for 40 h, the
reaction was diluted with MeOH, and the catalyst was removed
from the system by centrifugation or by passing through a short
silica gel column. The solution was analyzed by GC (GC-1690
Kexiao Co., with a flame ionization detector) with a flexible quartz
capillary column coated with FFAB.
3
+
nism, as exemplified by Co /salen-catalyzed epoxide hydra-
tion. An efficient heterogeneous catalyst that has an extremely
3+
high concentration of Co /salen has been synthesized from
the polymerization of vinyl-functionalized salen ligand mono-
3+
3+
mer followed by the introduction of Co species (Co /POL-
salen). Interestingly, in comparison with that of the homogene-
3+
3
+
Recycling of Co /POL-salen
ous Co /salen catalytic system, a significant rate acceleration
3
+
was observed for Co /POL-salen in epoxide hydration. The
After the reaction, the solid catalyst was separated by centrifuga-
tion and washed thoroughly with CH Cl and MeOH. The catalyst
3
+
high concentration of the Co /salen confined in the heteroge-
neous catalyst is responsible for the extraordinary activities of
2
2
was regenerated by treating it with AcOH/PhMe (1:9 v/v, 5.0 mL)
under air for 3 h. The catalyst was isolated, dried under vacuum,
and used in the next cycle.
3+
Co /POL-salen. In addition, the excellent hydrothermal stabili-
ty of the catalyst is helpful for the long-term industrial applica-
tions in epoxide hydration. This approach to prepare porous
organic ligand materials offers a good opportunity to design
heterogeneous catalysts rationally and efficiently in the future.
Characterization methods
N sorption isotherms at 77 K were measured by using Micromerit-
2
ics ASAP 2020M and Tristar systems. The samples were outgassed
for 10 h at 1008C before the measurements. ICP-OES was mea-
sured by using a PerkinElmer plasma OES8000. H NMR spectra
Experimental Section
1
were recorded by using a Bruker Avance-400 (400 MHz) spectrome-
ter. Chemical shifts are expressed in ppm downfield from TMS at
d=0 ppm, and J values are given in Hz. C (100.5 MHz) cross-po-
larization magic-angle spinning (CP-MAS) solid-state NMR spectra
were recorded by using a Varian infinity plus 400 spectrometer
Chemicals and materials
Solvents were purified according to standard laboratory methods.
For example, THF was distilled over sodium/benzophenone, and
toluene was distilled over calcium hydride. Azobisisobutyronitrile
13
(
AIBN), DVB, and ethylbenzene were obtained from Tianjin Guang-
equipped with a magic-angle spin probe in a 4 mm ZrO rotor. UV/
2
fu Chemical Reagent. SnCl , 4-vinylphenylboronic acid, paraformal-
4
Vis spectra were recorded by using a Shimadzu UV2450 spectrom-
eter. SEM was performed by using a Hitachi SU 1510. TEM was per-
formed by using a Hitachi HT-7700.
dehyde, Co(OAc) ·4H O, 3-tert-butylphenol, 1,2-cyclohexanedi-
2
2
amine, and tributylamine were purchased from Aladdin Company,
Co. Ltd and were used directly without further purification.
Acknowledgements
Synthesis of POL-salen
This work was supported by the National Natural Science Foun-
dation of China (21333009, 21422306), Fundamental Research
Funds for the Central Universities (2015XZZX004-04), and Zhe-
jiang Provincial Natural Science Foundation of China under
Grant No. LR15B030001.
POL-salen was synthesized by polymerization. Typically, vinyl-func-
tionalized salen monomer (0.5 g) was dissolved in NMP (5.0 mL),
and AIBN (20 mg) was added. The mixture was transferred into an
autoclave at 1008C and maintained for 24 h. After extraction with
CH Cl , a yellow solid with a yield higher than 99.0% was obtained.
2
2
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[
36] S. De, A. Balu, J. C. van der Waal, R. Luque, ChemCatChem 2015, 7,
Keywords: cobalt · heterogeneous catalysis · mesoporous
materials · microporous materials · polymers
1608–1629.
[37] Z.-A. Qiao, S.-H. Chai, K. Nelson, Z. Bi, J. Chen, S. M. Mahurin, X. Zhu, S.
Dai, Nat. Commun. 2014, 5, 3705.
[
38] B. Li, Y. Zhang, R. Krishna, K. Yao, Y. Han, Z. Wu, D. Ma, Z. Shi, T. Pham, B.
Space, J. Liu, P. K. Thallapally, J. Liu, M. Chrzanowski, S. Ma, J. Am. Chem.
Soc. 2014, 136, 8654–8660.
[
[
1] W.-Y. Gao, M. Chrzanowski, S. Ma, Chem. Soc. Rev. 2014, 43, 5841–5866.
2] Z.-A. Qiao, P. Zhang, S.-H. Chai, M. Chi, G. M. Veith, N. C. Gallego, M.
Kidder, S. Dai, J. Am. Chem. Soc. 2014, 136, 11260–11263.
[
[
[
[
[
39] Y. Zhang, B. Li, S. Ma, Chem. Commun. 2014, 50, 8507–8510.
40] P. Kaur, J. T. Hupp, S. T. Nguyen, ACS Catal. 2011, 1, 819–835.
41] Y. Zhang, S. N. Riduan, Chem. Soc. Rev. 2012, 41, 2083–2094.
42] E. B. Anderson, M. R. Buchmeiser, ChemCatChem 2012, 4, 30–44.
43] Q. Zhao, P. Zhang, M. Antonietti, J. Yuan, J. Am. Chem. Soc. 2012, 134,
[
3] D. Wang, R. Cai, S. Sharma, J. Jirak, S. K. Thummanapelli, N. G. Akhme-
dov, H. Zhang, X. Liu, J. L. Petersen, X. Shi, J. Am. Chem. Soc. 2012, 134,
9
012–9019.
4] R. G. Konsler, J. Karl, E. N. Jacobsen, J. Am. Chem. Soc. 1998, 120,
0780–10781.
5] H. Steinhagen, G. Helmchen, Angew. Chem. Int. Ed. Engl. 1996, 35,
339–2342; Angew. Chem. 1996, 108, 2489–2492.
6] Y. Wang, G. Ye, H. Chen, X. Hu, Z. Niu, S. Ma, J. Mater. Chem. A 2015, 3,
5292–15298.
[
[
[
1
11852–11855.
[
44] K. K. Tanabe, M. S. Ferrandon, N. A. Siladke, S. J. Kraft, G. Zhang, J.
Niklas, O. G. Poluektov, S. J. Lopykinski, E. E. Bunel, T. R. Krause, J. T.
Miller, A. S. Hock, S. T. Nguyen, Angew. Chem. Int. Ed. 2014, 53, 12055–
2
1
1
2058; Angew. Chem. 2014, 126, 12251–12254.
45] Q. Fang, S. Gu, J. Zheng, Z. Zhuang, S. Qiu, Y. Yan, Angew. Chem. Int. Ed.
014, 53, 2878–2882; Angew. Chem. 2014, 126, 2922–2926.
[
[
[
7] D. S. Su, S. Perathoner, G. Centi, Chem. Rev. 2013, 113, 5782–5816.
8] M. Sawamura, Y. Ito, Chem. Rev. 1992, 92, 857–871.
9] M. Shibasaki, N. Yoshikawa, Chem. Rev. 2002, 102, 2187–2210.
[
[
[
[
[
[
2
46] Q. Fang, Z. Zhuang, S. Gu, R. B. Kaspar, J. Zheng, J. Wang, S. Qiu, Y. Yan,
Nat. Commun. 2014, 5, 4503.
47] Q. Sun, Z. Dai, X. Liu, N. Sheng, F. Deng, X. Meng, F.-S. Xiao, J. Am.
Chem. Soc. 2015, 137, 5204–5209.
48] Q. Sun, M. Jiang, Z. Shen, Y. Jin, S. Pan, L. Wang, X. Meng, W. Chen, Y.
Ding, J. Li, F.-S. Xiao, Chem. Commun. 2014, 50, 11844–11847.
49] Y. Huangfu, Q. Sun, S. Pan, X. Meng, F.-S. Xiao, ACS Catal. 2015, 5,
[
10] H. Peng, N. G. Akhmedov, Y.-F. Liang, N. Jiao, X. Shi, J. Am. Chem. Soc.
015, 137, 8912–8915.
11] C. Baleiz¼o, H. Garcia, Chem. Rev. 2006, 106, 3987–4043.
12] R. Cai, M. Lu, E. Y. Aguilera, Y. Xi, N. G. Akhmedov, J. L. Petersen, H.
Chen, X. Shi, Angew. Chem. Int. Ed. 2015, 54, 8772–8776; Angew. Chem.
2
[
[
2015, 127, 8896–8900.
[
[
[
[
[
[
[
[
[
13] B. M. Trost, V. S. C. Yeh, Angew. Chem. Int. Ed. 2002, 41, 861–863;
Angew. Chem. 2002, 114, 889–891.
14] J.-A. Ma, D. Cahard, Angew. Chem. Int. Ed. 2004, 43, 4566–4583; Angew.
Chem. 2004, 116, 4666–4683.
1
556–1559.
50] Y. Xie, T.-T. Wang, X.-H. Liu, K. Zou, W.-Q. Deng, Nat. Commun. 2013, 4,
960.
1
[
[
51] K. S. W. Sing, Pure Appl. Chem. 1987, 57, 603–619.
52] J. Rouquerol, D. Avnir, C. W. Fairbridge, D. H. Everett, J. M. Haynes, N.
Pernicone, J. D. F. Ramsay, K. S. W. Sing, K. K. Unger, Pure Appl. Chem.
15] M. Tokunaga, J. F. Larrow, F. Kakiuchi, E. N. Jacobsen, Science 1997, 277,
9
36–938.
16] B. M. Rossbach, K. Leopold, R. Weberskirch, Angew. Chem. Int. Ed. 2006,
5, 1309–1312; Angew. Chem. 2006, 118, 1331–1335.
17] X. Zheng, C. W. Jones, M. Weck, J. Am. Chem. Soc. 2007, 129, 1105–
112.
18] R. Breinbauer, E. N. Jacobsen, Angew. Chem. Int. Ed. 2000, 39, 3604–
607; Angew. Chem. 2000, 112, 3750–3753.
1994, 66, 1739–1758.
4
[
53] B.-L. Su, C. Sanchez, X.-Y. Yang, Hierarchically Structured Porous Materials
from Nanoscience to Catalysis, Separation, Optics, Energy, and Life Sci-
ence, Wiley-VCH, Weinheim, 2012.
54] W. Xuan, C. Zhu, Y. Liu, Y. Cui, Chem. Soc. Rev. 2012, 41, 1677–1695.
55] P. Zhang, H. Zhu, and S. Dai, ChemCatChem 2015, DOI: 10.1002/
cctc.201500368.
1
[
[
3
19] K. Venkatasubbaiah, Y. Feng, T. Arrowood, P. Nickias, C. W. Jones, Chem-
CatChem 2013, 5, 201–209.
[
[
56] X. Zheng, C. W. Jones, M. Weck, Chem. Eur. J. 2006, 12, 576–583.
57] R. E. Kirk, D. F. Othmer in Encyclopedia of Chemical Technology (Ed.: A.
Seidel), Wiley, New York, 2005, pp. 644–660.
20] S. Bai, B. Li, J. Peng, X. Zhang, Q. Yang, C. Li, Chem. Sci. 2012, 3, 2864–
2
867.
21] M. Shakeri, R. J. M. K. Gebbink, P. E. de Jongh, K. P. de Jong, Angew.
Chem. Int. Ed. 2013, 52, 10854–10857; Angew. Chem. 2013, 125, 11054–
[
58] K. Weissermel, H. J. Arpe, Industrial Organic Chemistry, Wiley-VCH, Wein-
heim, 1993.
1
1057.
22] C. Zhu, G. Yuan, X. Chen, Z. Yang, Y. Cui, J. Am. Chem. Soc. 2012, 134,
058–8061.
23] H. Q. Yang, L. Zhang, L. Zhong, Q. Yang, C. Li, Angew. Chem. Int. Ed.
007, 46, 6861–6865; Angew. Chem. 2007, 119, 6985–6989.
24] B. Li, S. Bai, X. Wang, M. Zhong, Q. Yang, C. Li, Angew. Chem. Int. Ed.
012, 51, 11517–11521; Angew. Chem. 2012, 124, 11685–11689.
25] W. Zhang, Y. Hu, J. Ge, H.-L. Jiang, S.-H. Yu, J. Am. Chem. Soc. 2014, 136,
6978–16981.
[
[
[
59] J. W. Van Hal, J. S. Ledford, X. Zhang, Catal. Today 2007, 123, 310–315.
60] D. F. Othmer, M. S. Thakar, Ind. Eng. Chem. 1958, 50, 1235–1244.
61] V. F. Shvets, R. A. Kozlovskiy, I. A. Kozlovskiy, M. G. Makarov, J. P. Suchkov,
A. V. Koustov, Org. Process Res. Dev. 2005, 9, 768–773.
62] Y. C. Li, S. R. Yan, L. P. Qian, W. M. Yang, Z. K. Xie, Q. L. Chen, B. Yue, H. Y.
He, J. Catal. 2006, 241, 173–179.
[
[
[
[
8
2
[
[
2
63] Y. C. Li, S. R. Yan, B. Yue, W. M. Yang, Z. K. Xie, Q. L. Chen, H. Y. He, Appl.
Catal. A 2004, 272, 305–310.
1
[
[
64] B. C. Gates, Catalytic Chemistry, Wiley, New York, 1992.
65] F. Zhang, X. Yang, F. Zhu, J. Huang, W. He, W. Wang, H. Li, Chem. Sci.
[
[
[
26] K. K. Tanabe, S. M. Cohen, Chem. Soc. Rev. 2011, 40, 498–519.
27] J. B. DeCoste, G. W. Peterson, Chem. Rev. 2014, 114, 5695–5727.
28] F.-S. Xiao, Y. Han, X. Meng, M. Yang, S. Wu, J. Am. Chem. Soc. 2002, 124,
2
012, 3, 476–484.
66] D. E. De Vos, M. Dams, B. F. Sels, P. Jacobs, Chem. Rev. 2002, 102, 3615–
640.
[
[
[
8
88–889.
3
[
[
[
29] D. Zhao, J. Feng, Q. Huo, N. Melosh, G. H. Fredrickson, B. F. Chmelka,
G. D. Stucky, Science 1998, 279, 548–552.
30] C. E. Chan-Thaw, A. Villa, P. Katekomol, D. S. Su, A. Thomas, L. Prati,
Nano Lett. 2010, 10, 537–541.
67] K. G. M. Laurier, F. Vermoortele, R. Ameloot, D. E. De Vos, J. Hofkens,
M. B. J. Roeffaers, J. Am. Chem. Soc. 2013, 135, 14488–14491.
68] F. Vermoortele, M. Vandichel, B. V. de Voorde, R. Ameloot, M. Waroquier,
V. Van Speybroeck, D. E. De Vos, Angew. Chem. Int. Ed. 2012, 51, 4887–
31] S. Fischer, J. Schmidt, P. Strauch, A. Thomas, Angew. Chem. Int. Ed. 2013,
4890; Angew. Chem. 2012, 124, 4971–4974.
5
2, 12174–12178; Angew. Chem. 2013, 125, 12396–12400.
[
[
32] M. Rose, ChemCatChem 2014, 6, 1166–1182.
33] L. Wang, J. Zhang, J. Sun, L. Zhu, H. Zhang, F. Liu, D. Zheng, X. Meng, X.
Shi, F.-S. Xiao, ChemCatChem 2013, 5, 1606–1613.
Received: November 5, 2015
Revised: December 12, 2015
[
[
34] P. Zhang, Z. Weng, J. Guo, C. Wang, Chem. Mater. 2011, 23, 5243–5249.
35] Z. Ma, J. Yu, S. Dai, Adv. Mater. 2010, 22, 261–285.
Published online on January 15, 2016
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