Multilayered supported ionic liquids bearing a carboxyl group: Highly efficient catalysts for chemical fixation of carbon dioxide

Journal of Environmental Chemical Engineering 4 (2016) 2565–2572

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Multilayered supported ionic liquids bearing a carboxyl group: Highly efficient catalysts for chemical fixation of carbon dioxide Xu Zhanga , Wenhao Genga , Chengtao Yuea , Wei Wua,** , Linfei Xiaoa,b,* a National Center for International Joint Research on Catalytic Technology, Key Laboratory of Chemical Engineering Process & Technology for High-Efficiency Conversion, College of Heilongjiang Province, School of Chemistry and Material Sciences, Heilongjiang University, Harbin 150080, PR China b State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, PR China

A R T I C L E I N F O

Article history: Received 17 February 2016 Received in revised form 26 April 2016 Accepted 2 May 2016 Available online 3 May 2016 Keywords: Multilayered supported ionic liquids Carbon dioxide Epoxide Cyclic carbonate

A B S T R A C T

A series of carboxyl functional multilayered supported ionic liquids were synthesized and used as efficient catalysts for chemical fixation of carbon dioxide to form cyclic carbonates without any cosolvent and co-catalyst. The excellent yield and selectivity of cyclic carbonate were given with using PSImEImECOOHI2 as a catalyst at 120
C and 2.0 MPa for 2.0 h. The synergistic effect of anions and cations in multilayered supported ionic liquids contributed to the good catalytic activity for the synthesis of cyclic carbonates from carbon dioxide and epoxide. Furthermore, the catalyst showed excellent stability and could be reused up to ten times without any significant loss of catalytic activity. ã 2016 Elsevier Ltd. All rights reserved.

1. Introduction Carbon dioxide is one of the most significant greenhouse gases which caused the global warming and climate change. But, as an abundant, inexpensive and non-toxic renewable C1 resource, CO2 can be used to synthesize various useful chemical products [1–6]. The chemical conversion of CO2 with epoxides to produce fivemembered cyclic carbonates is one of the most promising strategies for the chemical utilization of CO2 [7–9]. Cyclic carbonates are valuable fine organic chemicals, which can serve as polar aprotic solvents in organic synthesis, electrolytes in secondary batteries, monomers for polycarbonates and fine chemicals in biomedical synthesis [10]. Over the last decades, a wide range of catalysts have been developed for the synthesis of cyclic carbonate from CO2 and epoxides [11–13], such as metal oxides [14], alkali metal salts [15,16], organic bases [17,18], transition metal complexes [19–23], N-heterocyclic carbene [24], organocatalyst [25,26], molecular sieves [27,28], metal organic frameworks [29–32] and ionic liquids [33–37], and so on. Although many homogeneous and heterogeneous catalysts systems reported so far are satisfactory in activity

* Corresponding author at: National Center for International Joint Research on Catalytic Technology, Key Laboratory of Chemical Engineering Process & Technology for High-Efficiency Conversion, College of Heilongjiang Province, School of Chemistry and Material Sciences, Heilongjiang University, Harbin 150080, PR China. ** Corresponding author. E-mail addresses: [email protected] (W. Wu), [email protected] (L. Xiao). http://dx.doi.org/10.1016/j.jece.2016.05.001 2213-3437/ ã 2016 Elsevier Ltd. All rights reserved.

and/or reusability, and there are disadvantages such as harsh reaction conditions, water sensitivity of the metal-containing catalysts, and additional volatile organic solvents needed. Hence, developing an efficient catalyst with metal- and solvent- free for the synthesis of cyclic carbonates from carbon dioxide and epoxides under mild conditions is still an interesting topic. Recently, multi-cation ionic liquids have been attracting great interests [38–41]. Compared to traditional mono-cation ionic liquids, multi-cation ionic liquids have advantages in term of thermal stability and volatility, as well as tenability of physical and chemical properties [42]. Potentially, they can be used as lubricants [43] and solvents [44–46] for high-temperature uses, gas chromatography stationary phases [47], and catalysts for esterification [48] and transesterification reactions [49]. In 2014, Wong et al. found the multi-cation ionic liquids were efficient catalysts for synthesis of cyclic carbonate from carbon dioxide and epoxide [50], and when the ZnI2 was employed as a Lewis acid, the catalytic activity of multi-cation ionic liquids were improved [51]. In our laboratory, we worked to develop task-specific ionic liquid catalysts for the conversion carbon dioxide to cyclic carbonates [52]. When cyclic carbonates were synthesized by using carboxyl functional ionic liquids as a catalyst [34], we found that the hydrogen bond was formed between epoxide and ionic liquids and the highly catalytic activity were shown in the coupling reaction. In the present work, a series of carboxyl functional multilayered supported ionic liquids were synthesized and used as catalysts for the synthesis of cyclic carbonate from epoxide and carbon dioxide. Under the optimized reaction conditions, the catalysts showed a

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high activity without using transition metal additives and cosolvents. And the reusability of carboxyl functional multilayered supported ionic liquids was also explored.

PS

N

N N Br BrPS-ImEImCOOHBr2 N

COOH

PS

N

N N I IPS-ImEImCOOHI2 N

COOH

2. Experimental PS

2.1. Materials and methods Propylene oxide was produced by Sinopharm Chemical Reagent Co., Ltd., glycidyl phenyl ether, epichlorohydrin, styrene oxide and cyclohexene oxide were purchased from Aldrich Chemical Co., Ltd. The CO2 (99.99%) was obtained from Qinghua Gas Co., Ltd. The other organic compounds were purchased from commercial market and used without further purification. The FT-IR spectra were measured on a PerkinElmer spectrum 100 spectrometer. Elemental analysis was performed over a Vario micro element analyzer. NMR spectra were recorded on a Bruker 400 MHz NMR spectrometer. The products were analyzed by a HP 6890/5973 GC– MS and an Agilent 6820 gas chromatography equipped with a flame-ionized detector.

N

N N Br PS-ImEImEtBr2

N

Br-

Fig. 1. The structure of immobilized ionic liquids.

excess CO2 was released slowly. The resulting mixture was transferred to a 50 mL round bottom flask. By distillation under vacuum, the product propylene carbonate 2a was obtained as a colorless liquid. The products were analyzed by a HP 6890/5973 GC–MS. In order to investigate the reusability of multilayered supported ionic liquids, the catalyst was separated from the resulting mixture by filtration and reused directly in the next reaction without further treatment. 3. Results and discussions

2.2. Preparation of multilayered supported ionic liquids 3.1. Characterization of the catalysts Firstly, 1-(2-bromoethyl)-3-(2-nitrilethyl)imidazolium bromide (BrEImECNBr) was synthesized (Scheme 1): A mixture of 1-(2-nitrilethyl)imidazole (ImECN) (10 mmol), 1,2-dibromoethane (15 mmol), and acetone (20 mL) was refluxed in a round bottom flask (100 mL) for 24 h. Then the solvent was evaporated and the reaction product was washed with ethyl acetate. Followed by drying at 60
C in vacuum for overnight, BrEImECNBr was obtained as a white solid. According to Scheme 1, BrEImECNBr was grafted onto polystyrene (PS) resin to produce multilayered supported ionic liquids. A mixture of BrEImECNBr (10 mmol), PS-Im (2.0 g), and acetone (15 mL) was placed in a round bottom flask (100 mL) under refluxing for 24 h. Then, the solid was filtered and washed three times with ethanol. After dried overnight in vacuum at 60
C, the PS-ImEImECNBr2 was acquired. Then, PS-ImEImECNBr2 (10 mmol) was added into the HCl aqueous solution and refluxing for overnight. Following this, the solvent was removed and the PSImEImECOOHCl2 was obtained. The synthesis procedure of multilayered supported ionic liquid PS-ImEImEtBr2 and PS-ImEImCOOHBr2 was similar to that of PSImEImCOOHCl2, and PS-ImEImCOOHI2 was prepared by anion exchange of PS-ImEImCOOHCl2 (Fig. 1). 2.3. Coupling propylene oxide and CO2 to produce cyclic carbonate The coupling reaction was carried out in a 50 mL stainless steel autoclave equipped with a magnetic stirrer (Scheme 2). The catalyst (0.52 mol%) and propylene oxide 1a (5.0 mL, 71.5 mmol) were charged into the reactor vessel without using any co-solvent and co-catalyst. The reaction was placed under a constant pressure of CO2 and then heated to the required temperature. After reaction completed, the reactor was cooled to room temperature and the

NC

PS

N

N

N

Br

Br

N N Br BrPS-ImEImCNBr2 N

Acetone Reflux

NC

N

CN HCl, H2O PS

N

N

Br

PS

N

FT-IR spectroscopy provided effective evidences for the grafting of carboxyl functional multi-cation ionic liquid onto polystyrene via a covalent bond. As shown in Fig. 2, PS-Cl exhibited the characteristic absorption peaks of C-Cl at 1265 cm1 and 670 cm1. When the imidazole was grafted on PS, three characteristics peaks centered at 1626 cm1, 1553 cm1, 1135 cm1, respectively, were corresponded to the feature band absorption of the imidazole ring. On the other hand, those peaks were absent in non-functionalized polystyrene resin PS-Cl. In comparison with PS-Im, PS-ImEImECNBr2 demonstrated newly developed CRN at 2250 cm1, which confirmed the successful grafting of multi-cation ionic liquid onto polystyrene resin. Furthermore, the band at 1723 cm1 of COOH group absorption was appeared in the FT-IR spectra when the PS-ImEImECNBr2 was hydrolyzed in hydrobromic acid aqueous, which suggested PS-ImEImECOOHBr2 was obtained. The structures of PS-ImEImECOOHI2 were well represented by 13 C solid-state NMR spectra, as shown in Fig. 3. PS-ImEImECOOHI2: d/ppm = 38.7, 51.0 (aliphatic skeleton), 127.9, 128.6, 144.2 (aromatic polystyrene skeleton and imidazolium ring skeleton), 170.2 (carboxyl group skeleton). According to the literature [53,54], all the peaks of 13C MAS NMR were assigned. And 13C MAS NMR was coincide with the results of FT-IR and in fair agreement with the structures of the target product as shown in Fig. 2. SEM reflected the morphology and surface shape of PS-Im and PS-ImEImECOOHI2. As shown in Fig. 4a and b, the surface of PS-Im was smooth. With the grafting of ionic liquid on the material, there was clear roughening of surface (Fig. 4c and d). It suggested that carboxyl functional multi-cation ionic liquid was supported on the PS resin successfully. The loading of ionic liquid grafted on PS was determined by elemental analysis (EA), and the results were shown in Table 1. The result of PS-ImEImECOOHI2 shown that there was 6.98 wt% of N

N

Br-

O

N

Cl-

N

N

COOH Cl-

R

O +

CO2 Multilayered supported ionic liquid

O

O

1a R 2a

PS-ImEImCOOHCl2

Scheme 1. Procedure for the preparation of supported dicationic ionic liquids.

Scheme 2. Synthesis of cyclic carbonates using multilayered supported ionic liquids.

X. Zhang et al. / Journal of Environmental Chemical Engineering 4 (2016) 2565–2572

d

Transmittance / %

1723 cm

-1

c 2250 cm

b

-1

1626 cm

-1

1553 cm

-1

1135 cm

-1

a 1265 cm

4000

3500

3000

2500

2000

Wavenumber / cm

1500

-1

1000

670 cm

-1

500

-1

Fig. 2. FT-IR spectra comparison of: (a) PS-Cl, (b)PS-Im, (c) PS-ImEImECNBr2, (d) PSImEImECOOHBr2.

element in the catalyst, demonstrating 1.25 mmol/g of ionic liquid was immobilized on the PS. And the fixing amount of PSImEImEBr2, PS-ImEImECNBr2, PS-ImEImECOOHCl2 and PS-ImEImECOOHBr2 were 1.45 mmol/g, 1.50 mmol/g, 1.44 mmol/g and 1.37 mmol/g, respectively. 3.2. Catalytic performance A series of different multilayered supported ionic liquids were synthesized and their catalytic performances for cycloaddtion of carbon dioxide and propylene oxide were investigated. And the results were depicted in Table 2. It can be seen that no product was detected in the reaction mixture without a catalyst or just using the polystyrene resin (PS-Cl) as a catalyst (Table 2, entries 1 and 2). With the introduction of ionic liquids on the PS-Cl, there is an improvement of the catalytic activity. When using PS-ImEImEBr2 as a heterogeneous catalyst for converting CO2 into cyclic carbonate, the middle yield of propylene carbonate was obtained (Table 2, entry 3). When PS-ImEImECNBr2, functionalized by nitrile group, was employed as a catalyst, the propylene carbonate was yield to 43.5  1.5% (Table 2, entry 4). It was because that the weak

Fig. 3.

13

C MAS NMR spectra of PS-ImEImECOOHI2.

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hydrogen bonds were formed between ionic liquid and propylene oxide [55] and it couldn’t effectively activate propylene oxide. In the previous work, it was found carboxylic group, as a hydrogen bond donor, could activate epoxide by the hydrogen bond between the H of carboxylic group and O from epoxide, and accelerated synthesis of cyclic carbonate from carbon dioxide and epoxides [34]. The multilayered supported ionic liquids with carboxylic group were prepared by the acidolysis of PS-ImEImECNBr2. To our delight, when introduce carboxyl group into ionic liquids, the catalytic activity of multilayered supported ionic liquid was improved. When the PS-ImEImECOOHBr2 was employed as a catalyst in the cycloaddition of carbon dioxide and propylene oxide, the yield of propylene carbonate was increased to 62.6  1.3% (Table 2, entry 6). It was because the stronger hydrogen bond was formed between the ionic liquid and propylene oxide and propylene oxide was activated. In the literatures [56], it was reported halide anion of ionic liquid had great influence on the catalytic activity in this reaction. Multilayered supported carboxylic functional ionic liquids with different halide anion were synthesized. When Cl was used as an anion of supported ionic liquid, the yield of propylene carbonate was decreased to 52.2  1.4% (Table 2, entry 5). While, multilayered supported ionic liquid PS-ImEImECOOHI2 was chosen as a catalyst, the yield of propylene carbonate was achieved 76.3  1.6% (Table 2, entry 7). On the basis of these results, it can be seen that the catalytic activity of the halide anions decrease in the order of I > Br > Cl (Table 2, entries 3–5). According to the mechanism proposed in previous works [37], it was because that I shown the best nucleophilicity and leaving ability in the processes for activating propylene oxide and intramolecular ring closing to form propylene carbonate. From Table 2, it can be seen that the yield of propylene carbonate was increased with increasing the concentration of supported ionic liquid catalyst PS-ImEImECOOHI2. In the presence of 0.87 mol% PSImEImECOOHI2, propylene carbonate was yield to 94.4  1.6% (Table 2, entry 10). And further increasing the amount of ionic liquid catalyst to 1.00 mol%, the yield of propylene carbonate was improved slightly (Table 2, entry 11). 3.3. Effects of reaction parameters Since the PS-ImEImECOOHI2 showed good catalytic activity in the cycloaddition reaction, the effects of reaction parameters (temperature, CO2 pressure, and time) were further investigated with PS-ImEImECOOHI2 catalytic system. Firstly, the influence of reaction temperature on the synthesis of cyclic carbonate was investigated and the results were shown in Fig. 5. From Fig. 5, it can be seen that the temperature has a pronounced positive effect on the cycloaddition reaction. When the temperature was raised from 90
C to 120
C, the yield of propylene carbonate was increased. To our delight, the selectivity to propylene carbonate (99%) was not affected by the temperature. But a further rise to 130
C, the yield of propylene carbonate was improved slightly. Therefore, the optimal reaction temperature was 120
C in the presence of PS-ImEImECOOHI2. A significant drawback associated with using carbon dioxide as a reagent in organic synthesis is the potential dangers associated with operating at high pressures. In order to select the optimum reaction pressure, the effect of pressure on coupling carbon dioxide and propylene oxide was particularly investigated (Fig. 6). Interestingly, the yield of propylene carbonate was sensitive to CO2 pressure when the reaction pressure was under 2.0 MPa. When the reaction was carried out at 0.5 MPa, the yield of propylene carbonate was lower than 20%. With increasing the reaction pressure to 2.0 MPa, the yield of propylene carbonate was enhanced to 94.4  1.6%. According to the previous literatures [36], the results were attributed to the phase behavior involving

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Fig. 4. SEM image of multilayered immobilized ionic liquids: (a and b) PS-Im and (c and d) PS-ImEImECOOHI2.

CO2-rich gas phase and liquid phase in this heterogeneous catalytic system. The initial increase of CO2 pressure resulted in the enhancement of CO2 concentration in propylene oxide or “liquefies” through the formation of a CO2-propylene oxide complex, thus improving the propylene carbonate yield. However, further increasing CO2 pressure up to 2.5 MPa, the yield of propylene carbonate was decreased, it was because that the higher pressure extracted more propylene oxide into the gas phase, causing the reduction of propylene oxide concentration in the vicinity of the catalysts in the liquid phase [54]. Conclusively, 2.0 MPa was the optimal CO2 pressure for propylene carbonate synthesis from carbon dioxide and propylene oxide. In order to obtain the optimal reaction pressure and temperature, the 3-dimensional graph on the pressure-temperature-yield domain was shown in Fig. 7. From Fig. 7, it can be seen that the highest yield of propylene carbonate was given when the reaction pressure was 2.0 MPa and the reaction temperature was 120
C. Additionally, the effects of reaction time on the propylene carbonate synthesis were also evaluated under the conditions of 120
C and 2.0 MPa. From Fig. 8, it can be seen that it was beneficial to synthesis of propylene carbonate prolonging reaction time from 0.5 h to 2.0 h and the yield of propylene carbonate was sharply increased. However, the further extending reaction time to 2.5 h resulted in only a slight rise in propylene carbonate yield. Again, the selectivity to propylene carbonate stayed above 99% throughout. Therefore, a reaction time of 2.0 h is chose as the appropriate operating time.

Table 1 Elemental analysis of multilayered immobilized ionic liquids. Entry

Catalyst

N/%

C/%

H/%

Amount of IL/mmol g1

1 2 3 4 5

PS-ImEImEBr2 PS-ImEImECNBr2 PS-ImEImECOOHCl2 PS-ImEImECOOHBr2 PS-ImEImECOOHI2

8.14 8.43 8.08 7.66 6.98

60.33 65.87 60.93 56.79 52.75

6.24 6.85 6.60 5.95 5.30

1.45 1.50 1.44 1.37 1.25

3.4. Synthesis of other cyclic carbonates In order to study the efficiency and general applicability of the catalyst PS-ImEImECOOHI2, the cycloaddition of CO2 with various epoxides under optimal reaction conditions was carried out and the results were listed in Table 3. PS-ImEImECOOHI2 was found to be an effective catalyst for a variety of terminal epoxides producing corresponding cyclic carbonates with high yield and selectivity (Table 3, entries 1–4). When the epichlorohydrin 2a was used as a substrate, the excellent yield of corresponding cyclic carbonate 2b was obtained (entry 2), it was because the electron-withdrawing effect of its substituent, which facilitated nucleophilic attack to open the epoxide ring. In general, the styrene oxide 4a was a phenyl-substituted epoxide and its conversion to styrene carbonate 4b was low compared with that of 1a, and it was because a planar conformation allows the aromatic ring to stabilize the charge in the coordinated alkyloxide

Table 2 The effect of multilayered supported ionic liquid on the synthesis of propylene carbonate.a Entry

Catalyst

Selectivity%

Yieldb %

1 2 3 4 5 6 7 8c 9d 10e

PS-Cl None PS-ImEImEBr2 PS-ImEImECNBr2 PS-ImEImECOOHCl2 PS-ImEImECOOHBr2 PS-ImEImECOOHI2 PS-ImEImECOOHI2 PS-ImEImECOOHI2 PS-ImEImECOOHI2

– – 99 99 99 99 99 99 99 99

0 0 50.1  1.4 43.5  1.5 52.2  1.4 62.6  1.3 76.3  1.6 88.4  1.5 94.4  1.6 98.3  0.8

a Reaction conditions: supported ionic liquid 0.52 mol%, propylene oxide 71.5 mmol, reaction pressure 2.0 MPa, reaction temperature 120
C, reaction time 2.0 h. b Isolated yield. c Supported ionic liquid 0.70 mol%. d Supported ionic liquid 0.87 mol%. e Supported ionic liquid 1.00 mol%.

X. Zhang et al. / Journal of Environmental Chemical Engineering 4 (2016) 2565–2572

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100

100

90

80

Yield / %

Yield %

80

70

60

60

40

20

50

40

0

90

100

110

120

Re

o

Reaction temperature / C Fig. 5. The effect of temperature on the yield of propylene carbonate.

and the inductive effect of the phenyl group is responsible for stabilization of the charge in the transition state describing the ring-closing step [21,26] (entry 4). Additionally, we also examined the cyclohexene oxide 5a was used as a substrate in this coupling process. Because the higher hindrance created from the two rings of 5a, which obstructed the nucleophilic attack of I and caused the decrease of ring-opening rate, the middle yield of corresponding cyclic carbonate 5b was obtained when the reaction time was prolonged to 24 h (entry 5). 3.5. Catalyst reusability As we all know, the stability and reusability of a catalyst system are the two keys for its potentially practical application in industry. To evaluate the catalyst reusability, a set of reusing experiments were carried out under the optimal conditions when PSImEImECOOHI2 was employed as a catalyst and the corresponding catalytic results were listed in Fig. 9. After each reaction, the catalyst was recovered by simple filtration and directly used for the next reaction without any disposed. As shown in Fig. 8, the catalyst can be recycled at least ten times without obvious loss in catalytic activity and the yield of propylene carbonate has shown without

120

2.5

act ion 2.0 1.5 p re ssu re / 1.0 MP a

110 100 90

0.5 0.0

Re

ac

tio

em nt

pe

r

re atu

o

/

significant decreased. Moreover, the recovered catalyst (after ten runs) was characterized by FT-IR (Fig. 10). It was found that the FT-IR spectrum of the recovered catalyst was same to that of the fresh one. This result demonstrates that PS-ImEImECOOHI2 was highly stable in the synthesis of cyclic carbonate from epoxide and carbon dioxide. Consequently, the recyclability of the catalyst makes the process economically and potentially viable for commercial applications in the fixation of carbon dioxide to produce cyclic carbonate. Moreover, this organic solvent-free process presented here could show much potential application in industry due to its simplicity, easy product separation from reaction medium and catalyst recycling. 3.6. Possible reaction mechanism Based on the previous reports [34,37,51,56] and our experimental results, a reasonable catalytic cycle was supposed for the

100

90

Yield / %

80

60

40

80

70

60 20

50 0 0.5

1.0

1.5

2.0

2.5

Reaction pressure / MPa Fig. 6. The effect of CO2 pressure on the yield of propylene carbonate.

C

Fig. 7. 3-dimensional graph on the pressure-temperature-yield domain of propylene carbonate.

100

Yield %

130

3.0

130

0.5

1.0

1.5

2.0

2.5

Reaction time / h Fig. 8. The effect of reaction time on the yield of propylene carbonate.

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Table 3 Synthesis of cyclic carbonates from epoxides and CO2.a Entry

Substrate

Product

1

94.4  1.6

99

96.7  1.1

99

94.6  1.5

99

90.1  1.8

99

43.0  1.2

2b

2a 3

3a

3b

4

4b

4a 5b

5b

5a

b

Yield (%)

99

1b

1a 2

a

Selectivity (%)

Reaction conditions: epoxide 71.5 mmol, supported ionic liquid 0.87 mol%, reaction pressure 2.0 MPa, reaction temperature 120
C, reaction time 2.0 h. Reaction time 24.0 h.

coupling reaction from CO2 and propylene oxide in the presence of PS-ImEImECOOHI2. As depicted in Scheme 3, propylene oxide was firstly activated by the H atom in carboxylic acid group, C(2)-H of imidazolium and electronic interaction with the imidazolium dication, the I anions of the ionic liquid as a Lewis base subsequently attacked on the less sterically hindered b-carbon atom of epoxide to make the epoxy ring open to give the oxyanion intermediate (II). Then the oxy-anion intermediatemade (II) the

nucleophilic attack on CO2 species activated by tertiary nitrogen of imidazolium to produce an alkyl carbonate anion (III). Finally, the intermediate (III) further converted to the corresponding cyclic carbonate through intramolecular ring closing. In meantime, the catalyst was regenerated. During the entire process of reaction, the synergistic effect of polarization (due to hydrogen bonding) and electronic interaction (due to double imidazolium cations), as well

100

Recovered

Transmittance / %

90

Yield / %

80

70

60

Fresh

50

40 0

2

4

6

8

Recycle Fig. 9. Recycling experiments for PS-ImEImECOOHI2.

10

4000

3500

3000

2500

2000

wavenumber / cm

1500 -1

Fig. 10. FT-IR spectra of PS-ImEImECOOHI2.

1000

500

X. Zhang et al. / Journal of Environmental Chemical Engineering 4 (2016) 2565–2572

O O O

PS*

PS*

N

N I-

O

N

2

H O (III)

H

O

PS*

O

IN

2

O

O

H

IN

N H

O

(I)

I

O

2

O

H

O I-

O

I-

PS*

N O C O

N H

CO2

2

O (II)

O

H

O

I

Scheme 3. The possible mechanism for the coupling reaction in the presence of immobilized ionic liquids.

as the nucleophilic attack by the iodide anion, accounts for the excellent activity. 4. Conclusion In summary, a series of carboxyl functional multilayered supported ionic liquids were developed and it exhibited highly catalytic activity for the cycloaddition of CO2 with various epoxides without using additional co-catalyst and co-solvent. When the reaction was carried out with 0.87 mol% of catalyst at 120
C under 2.0 MPa of CO2 pressure for 2.0 h, the propylene carbonate yield reached 94.4  1.6%. During the entire process of reaction, the synergistic effect of polarization and electronic interaction, as well as the nucleophilic attack by the iodide anion, accounts for the excellent activity. As a heterogeneous catalyst, PS-ImEImEnOOHI2 can be recycled for at least ten times without obvious loss in activity. From the viewpoints of large-scale production and green chemistry, carboxyl functional multilayered supported ionic liquids is good candidate for further developments and applications in sustainable processes concerned with CO2 fixation the catalyst because of its activity, stability, and recyclability. Acknowledgments We are grateful to the Foundation for Youth Science and Technology Innovation Talents of Harbin of China (RC2013LX018002) and the Chinese National Sciences Foundation (21006021) and the State Key Laboratory of Chemical Resource Engineering (CRE-2015-C-302) for financial support. References [1] A. Pinaka, G.C. Vougioukalakis, Using sustainable metals to carry out green transformations Fe- and Cu-catalyzed CO2 monetization, Coord. Chem. Rev. 288 (2015) 69–97. [2] P. Kumar, P. With, V.C. Srivastava, R. Gläser, I.M. Mishra, Conversion of carbon dioxide along with methanol to dimethyl carbonate over ceria catalyst, J. Environ. Chem. Eng. 3 (2015) 2943–2947. [3] A. Mirvakili, H. Khalilpourmeymandi, M.R. Rahimpour, Reduction of gas emission via optimization of purified purge gas recycle ratio for conversion of CO2 to methanol, J. Environ. Chem. Eng. 4 (2016) 1348–1358. [4] M. Mikkelsen, M. Jorgensen, F.C. Krebs, The teraton challenge. A review of fixation and transformation of carbon dioxide, Energy Environ. Sci. 3 (2010) 43–81. [5] I. Omae, Recent developments in carbon dioxide utilization for the production of organic chemicals, Coord. Chem. Rev. 256 (2012) 1384–1405.

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[6] N.A.M. Razali, K.T. Lee, S. Bhatia, A.R. Mohamed, Heterogeneous catalysts for production of chemicals using carbon dioxide as raw material: a review, Renew. Sust. Energ. Rev. 16 (2012) 4951–4964. [7] X.B. Lu, W.M. Ren, G.P. Wu, CO2 copolymers from epoxides catalyst activity, product selectivity, and stereochemistry control, Acc. Chem. Res. 45 (2012) 1721–1735. [8] A.A.G. Shaikh, Organic carbonates, Chem. Rev. 96 (1996) 951–976. [9] L.F. Zhang, X.L. Fu, G.H. Gao, Anion-cation cooperative catalysis by ionic liquids, ChemCatChem 3 (2011) 1359–1364. [10] T. Sakakura, J.C. Choi, H. Yasuda, Transformation of carbon dioxide, Chem. Rev. 107 (2007) 2365–2387. [11] X.B. Lu, D.J. Darensbourg, Cobalt catalysts for the coupling of CO2 and epoxides to provide polycarbonates and cyclic carbonates, Chem. Soc. Rev. 41 (2012) 1462–1484. [12] P.P. Pescarmona, M. Taherimehr, Challenges in the catalytic synthesis of cyclic and polymeric carbonates from epoxides and CO2, Catal. Sci. Technol. 2 (2012) 2169–2187. [13] Y.G. Zhang, J.Y.G. Chan, Sustainable chemistry imidazolium salts in biomass conversion and CO2 fixation, Energy Environ. Sci. 3 (2010) 408–417. [14] W.L. Dai, S.L. Luo, S.F. Yin, C.T. Au, The direct transformation of carbon dioxide to organic carbonates over heterogeneous catalysts, Appl. Catal. A Gen. 366 (2009) 2–12. [15] M.R. Reithofer, Y.N. Sum, Y.G. Zhang, Synthesis of cyclic carbonates with carbon dioxide and cesium carbonate, Green Chem. 15 (2013) 2086–2090. [16] Z.L. Wu, H.B. Xie, X. Yu, E.H. Liu, Lignin-based green catalyst for the chemical fixation of carbon dioxide with epoxides to form cyclic carbonates under solvent-free conditions, ChemCatChem 5 (2013) 1328–1333. [17] M.S. Liu, B. Liu, L. Shi, F.X. Wang, L. Liang, J.M. Sun, Melamine-ZnI2 as heterogeneous catalysts for efficient chemical fixation of carbon dioxide to cyclic carbonates, RSC Adv. 5 (2015) 960–966. [18] J. Sun, W.G. Cheng, Z.F. Yang, J.Q. Wang, T.T. Xu, J.Y. Xin, S.J. Zhang, Superbase/ cellulose an environmentally benign catalyst for chemical fixation of carbon dioxide into cyclic carbonates, Green Chem. 16 (2014) 3071–3078. [19] Y.L. Shi, P. Zhang, D.H. Liu, P.F. Zhou, L.B. Sun, Homogenous dual-ligand zinc complex catalysts for chemical fixation of CO2 to propylene carbonate, Catal. Lett. 145 (2015) 1673–1682. [20] D.W. Tian, B.Y. Liu, Q.Y. Gan, H.R. Li, D.J. Darensbourg, Formation of cyclic carbonates from carbon dioxide and epoxides coupling reactions efficiently catalyzed by robust, recyclable one-component aluminum-salen complexes, ACS Catal. 2 (2012) 2029–2035. [21] F. Castro-Gómez, G. Salassa, A.W. Kleij, C. Bo, A DFT Study on the mechanism of the cycloaddition reaction of CO2 to epoxides catalyzed by Zn(salphen) complexes, Chem. A Eur. 19 (2013) 62896298. [22] J.A. Castro-Osma, M. North, X. Wu, Development of a halide-free aluminiumbased catalyst for the synthesis of cyclic carbonates from epoxides and carbon dioxide, Chem. A Eur. 20 (2014) 1500515008. [23] C. Maeda, T. Taniguchi, K. Ogawa, T. Ema, Bifunctional catalysts based on mphenylene-bridged porphyrin dimer and trimer platforms synthesis of cyclic carbonates from carbon dioxide and epoxides, Angew. Chem. Int. Ed. 54 (2015) 134–138. [24] Y. Kayaki, M. Yamamoto, T. Ikariya, N-heterocyclic carbenes as efficient organocatalysts for CO2 fixation reactions, Angew. Chem. Int. Ed. 48 (2009) 4194–4197. [25] H. Buttner, J. Steinbauer, T. Werner, Synthesis of cyclic carbonates from epoxides and carbon dioxide by using bifunctional one-component phosphorus-based organocatalysts, ChemSusChem 8 (2015) 2655–2669. [26] C.J. Whiteoak, A. Nova, F. Maseras, A.W. Kleij, Merging sustainability with organocatalysis in the formation of organic carbonates by using CO2 as a feedstock, ChemSusChem 5 (2012) 2032–2038. [27] F.Y. Zhang, Y.J. Xie, P.L. Ling, F. Hao, Z.J. Yao, H.A. Luo, Cycloaddition reaction of propylene oxide and carbon dioxide over NaX zeolite supported metalloporphyrin catalysts, Catal. Lett. 144 (2014) 1894–1899. [28] E.J. Doskocil, Effect of water and alkali modifications on ETS-10 for the cycloaddition of CO2 to propylene oxide, J. Phys. Chem. B 109 (2005) 2315–2320. [29] B. Zou, L. Hao, L.Y. Fan, Z.M. Gao, S.L. Chen, H. Li, C.W. Hu, Highly efficient conversion of CO2 at atmospheric pressure to cyclic carbonates with in situgenerated homogeneous catalysts from a copper-containing coordination polymer, J. Catal. 329 (2015) 119–129. [30] M.H. Beyzavi, R.C. Klet, S. Tussupbayev, J. Borycz, N.A. Vermeulen, C.J. Cramer, J. F. Stoddart, J.T. Hupp, O.K. Farha, A hafnium-based metal-organic framework as an efficient and multifunctional catalyst for facile CO2 fixation and regioselective and enantioretentive epoxide activation, J. Am. Chem. Soc. 136 (2014) 15861–15864. [31] W.Y. Gao, Y. Chen, Y.H. Niu, K. Williams, L. Cash, P.J. Perez, L. Wojtas, J.F. Cai, Y.S. Chen, S.Q. Ma, Crystal engineering of an nbo topology metal-organic framework for chemical fixation of CO2 under ambient conditions, Angew. Chem. Int. Ed. 53 (2014) 2615–2619. [32] A.C. Kathalikkattil, R. Babu, J. Tharun, R. Roshan, D.W. Park, Advancements in the conversion of carbon dioxide to cyclic carbonates using metal organic frameworks as catalysts, Catal. Surv. Asia 19 (2015) 223–235. [33] J.J. Peng, Y. Deng, Cycloaddition of carbon dioxide to propylene oxide catalyzed by ionic liquids, New J. Chem. 25 (2001) 639–641. [34] L.F. Xiao, D.W. Lv, D. Su, W. Wu, H.F. Li, Influence of acidic strength on the catalytic activity of Brønsted acidic ionic liquids on synthesizing cyclic carbonate from carbon dioxide and epoxide, J. Clean. Prod. 67 (2014) 285–290.

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X. Zhang et al. / Journal of Environmental Chemical Engineering 4 (2016) 2565–2572

[35] L.F. Xiao, D. Su, W. Wu, Protic ionic liquids a highly efficient catalyst for synthesis of cyclic carbonate from carbon dioxide and epoxides, J. CO2 Util. 6 (2014) 1–6. [36] S.M. Sadeghzadeh, A heteropolyacid-based ionic liquid immobilized onto fibrous nano-silica as an efficient catalyst for the synthesis of cyclic carbonate from carbon dioxide and epoxides, Green Chem. 17 (2015) 3059–3066. [37] B.H. Xu, J.Q. Wang, J. Sun, Y. Huang, J.P. Zhang, X.P. Zhang, S.J. Zhang, Polyethylene glycol functionalized dicationic ionic liquids with alkyl or polyfluoroalkyl substituents as high temperature lubricants, Green Chem. 17 (2015) 108–122. [38] M. Gruttadauria, L.F. Liotta, A.M.P. Salvo, F. Giacalone, V.L. Parola, C. Aprile, R. Noto, Multi-layered, covalently supported ionic liquid phase (mlc-SILP) as highly cross-linked support for recyclable palladium catalysts for the Suzuki reaction in aqueous medium, Adv. Synth. Catal. 353 (2011) 2119–2130. [39] X.Y. Shi, X.Y. Han, W.J. Ma, J.F. Wei, J. Li, Q. Zhang, Z.G. Chen, Peroxotungstates immobilized on multilayer ionic liquid brushes-modified silica as an efficient and reusable catalyst for selective oxidation of sulfides with H2O2, J. Mol. Catal. A Chem. 341 (2011) 57–62. [40] A. Pourjavadi, S.H. Hosseini, S.S. Amin, Novel high loaded magnetic nanocatalyst based on multilayered coating of poly(1-vinylimidazole), Chem. Eng. J. 247 (2014) 85–92. [41] P. Agrigento, S.M. Al-Amsyar, B. Sorée, M. Taherimehr, M. Gruttadauri, C. Aprile, P.P. Pescarmona, Synthesis and high-throughput testing of multilayered supported ionic liquid catalysts for the conversion of CO2 and epoxides into cyclic carbonates, Catal. Sci. Technol. 4 (2014) 1598–1607. [42] T. Payagala, J.M. Huang, Z.S. Breitbach, P.S. Sharma, D.W. Armstrong, Unsymmetrical dicationic ionic liquids Manipulation of physicochemical properties using specific structural architectures, Chem. Mater. 19 (2007) 5848–5850. [43] C.M. Jin, C. Ye, B.S. Phillips, J.S. Zabinski, X. Liu, J.M. Liu, W. Shreeve, Polyethylene glycol functionalized dicationic ionic liquids with alkyl or polyfluoroalkyl substituents as high temperature lubricants, J. Mater. Chem. 16 (2006) 1529–1535. [44] X. Han, D.W. Armstrong, Using geminal dicationic ionic liquids as solvents for high-temperature organic reactions, Org. Lett. 7 (2005) 4205–4208.

[45] J.C. Xiao, J.M. Shreeve, Synthesis of 2,20 -biimidazolium-based ionic liquids: use as a new reaction medium and ligand for palladium-catalyzed suzuki crosscoupling reactions, J. Org. Chem. 70 (2005) 3072–3078. [46] R. Wang, C.M. Jin, B. Twamley, J.M. Shreeve, Syntheses and characterization of unsymmetric dicationic salts incorporating imidazolium and triazolium functionalities, Inorg. Chem. 45 (2006) 6396–6403. [47] J.L. Anderson, D.W. Armstrong, Immobilized ionic liquids as high-selectivity/ high-temperature/high-stability gas chromatography stationary phases, Anal. Chem. 77 (2005) 6453–6462. [48] D.S. Zhao, M.S. Liu, J. Zhang, J.P. Li, P.B. Ren, Synthesis, characterization, and properties of imidazole dicationic ionic liquids and their application in esterification, Chem. Eng. J. 221 (2013) 99–104. [49] M.M. Fan, J. Yang, P.P. Jiang, P.B. Zhang, S.S. Li, Synthesis of novel dicationic basic ionic liquids and its catalytic activities for biodiesel production, RSC Adv. 3 (2013) 752–756. [50] W.L. Wong, L.Y.S. Lee, K.P. Ho, Z.Y. Zhou, T. Fan, Z.Y. Lin, K.Y. Wong, A green catalysis of CO2 fixation to aliphatic cyclic carbonates by a new ionic liquid system, Appl. Catal. A Gen. 472 (2014) 160–166. [51] M.S. Liu, L. Liang, T. Liang, X.L. Lin, L. Shi, F.X. Wang, J.M. Sun, Melamine-ZnI2 as heterogeneous catalysts for efficient chemical fixation of carbon dioxide to cyclic carbonates, J. Mol. Catal. A Chem. 408 (2015) 242–249. [52] L.F. Xiao, D.W. Lv, W. Wu, Brønsted acidic ionic liquids mediated metallic salts catalytic system for the chemical fixation of carbon dioxide to form cyclic carbonates, Cataly. Lett. 141 (2011) 1838–1844. [53] D.W. Kim, D.Y. Chi, Polymer-supported ionic liquids imidazolium salts as catalysts for nucleophilic substitution reactions including fluorinations, Angew. Chem. Int. Ed. 43 (2004) 483–485. [54] Y. Lin, F. Wang, Z.Q. Zhang, J. Yang, Y. Wei, Polymer-supported ionic liquids Synthesis, characterization and application in fuel desulfurization, Fuel 116 (2014) 273–280. [55] S. Marmitt, P.F.B. Gonçalves, A DFT study on the insertion of CO2 into styrene oxide catalyzed by 1-butyl-3-methyl-imidazolium bromide ionic liquid, J. Comput. Chem. 36 (2015) 1322–1333. [56] F.W. Li, L.F. Xiao, C.G. Xia, B. Hu, Chemical fixation of CO2 with highly efficient ZnCl2/[BMIm]Br catalyst system, Tetrahedron Lett. 45 (2004) 8307–8310.