A non-metal Schiff-base complex anchored cellulose as a novel and

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Kinetics, Catalysis, and Reaction Engineering

A non-metal Schiff-base complex anchored cellulose as a novel and reusable catalyst for the solventfree ring-opening addition of CO2 with epoxides Shiyu Chen, Manoj Pudukudy, Zhongxiao Yue, Heng Zhang, Yunfei Zhi, Yonghao Ni, Shaoyun Shan, and Qingming Jia Ind. Eng. Chem. Res., Just Accepted Manuscript • DOI: 10.1021/acs.iecr.9b03331 • Publication Date (Web): 24 Aug 2019 Downloaded from pubs.acs.org on August 25, 2019

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Industrial & Engineering Chemistry Research

A non-metal Schiff-base complex anchored cellulose as a novel and reusable catalyst for the solvent-free ring-opening addition of CO2 with epoxides

Shiyu Chena, Manoj Pudukudya, Zhongxiao Yuea, Heng Zhanga, Yunfei Zhia, Yonghao Nia, b, Shaoyun Shana, * and Qingming Jiaa, *

a

Faculty of Chemical Engineering, Kunming University of Science and Technology,

Kunming, Yunnan, 650500, China. b

Limerick Pulp and Paper Centre, University of New Brunswick, Fredericton, E3B

5A3, Canada.

* [email protected] * [email protected]

Abstract: The synthesis of metal-free heterogeneous catalyst in environmental catalysis has become a hot area of research. To achieve the goal of a sustainable recycling of biological resources and the mitigation of greenhouse gases, a novel metal-free cellulose-based Schiff-base heterogeneous catalyst (Cell-H2L) is reported in the ring-opening addition reaction of CO2 with epoxides to synthesize cyclic carbonates for the first time. The as-prepared samples were characterized by FT-IR, XPS, SEM, BET/BJH, solid-state NMR and TGA analyses. The successful anchoring of non-metal Schiff base complex on chlorinated cellulose is clearly evident from the structural composition studies. The catalytic activity results showed that the samples exhibited excellent catalytic performance in the solvent-free condition. The yield of resultant propylene carbonate was measured to be 98.7% with ~100% selectivity. The enhanced role of the present catalyst for the ring-opening addition could be attributed to the synergy of its structural hydroxyl, phenolic -OH and Lewis basic (imine) 1

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groups in the catalyst, which are capable of activating the epoxide and CO2, which efficiently participate in the reaction together with the substantial role of nucleophilic ionic (Br-) group from the co-catalyst. The catalyst was effectively reused for five consequent runs without a significant loss in the catalytic activity and showed high effectiveness for a series of other epoxides. Keywords: Metal-free catalyst; Carbon dioxide; Ring opening addition; Cyclic carbonate; Reusability studies

2


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1. Introduction Fossil fuels are the main source of energy in recent years. The utilization of fossil fuels by its combustion process released bulk amount of carbon dioxide into atmosphere. In addition to this, the increased human activities have also become a key factor for bulk CO2 emission. Both of these severely impacts on the global climate and contributes to global warming1-2. In order to reduce the extent of carbon emission, carbon capture and storage (CCS) strategies have been proposed. The utilization of carbon storage strategy requires a lot of energy and waste of our expense resources. Therefore, carbon capture and utilization (CCU) would be an attractive alternative for this limitation3-4. As per a recent report, more than 2 million tons of CO2 were used annually in the global market5. Carbon dioxide is a renewable raw material and plays a pivotal role in organic synthesis and in the production of commercially important chemicals6. As a potentially important carbon source, the chemical fixation and utilization of CO2 not only help to alleviate the ―greenhouse effect‖ caused by excessive CO2 emissions but also reduce the human dependence on non-renewable fossil resources such as coal, oil and natural gas7-9. It is of further great value to the global sustainable development. The use of CO2 to synthesize carbonate species is a great shift in the field of carbon emissions. Cyclic carbonates are a class of compounds that has been synthesized from CO2 and epoxides. Because of its high dipole moment, dielectric constant,

boiling

point,

non-toxicity,

biocompatibility and

high

structural

controllability, it is widely used as an electrolytic component, and also found promising application in the field of fine chemicals, biomedicine, polar aprotic solvents and also in lithium ion batteries10-11. In addition, it is often used in the synthesis of monomers of polyurethane, polycarbonates and polyglycerol12-17. The C=O bond length in CO2 is shorter than the normal C=O bond length due to its strong kinetic and thermodynamic stability18-19. Therefore, the conversion of CO2 to cyclic carbonate still remains as a challenging process. The research works that have been reported in last few years had shown that the 3



utilization of a good catalyst will increase the possibility of ring-opening addition reaction of CO2 with epoxide to synthesize cyclic carbonate. The most widely used catalysts are homogeneous in nature such as quaternary ammonium salts20-21, ionic liquids22-23, metal complexes24-25 and so on. In 2004, Li et al.26 proposed the use of a metal salt (ZnCl2), in combination with a conventional ionic liquid ([BMM]Br) to catalyze the synthesis of cyclic carbonate with high catalytic activity in the reaction. Woo et al.27 synthesized Al-Salen catalyst for the ring-opening addition reaction of CO2 with propylene oxide. The experimental results had showed that at room temperature and a CO2 pressure of 0.5 MPa, the PC yield was 87% for a reaction period of 12 h. In addition, Kleij25 et al. reviewed the catalytic conversion of CO2 using several homogeneous metal-containing catalysts and a detailed discussion has been reported in the activity, product selectivity and mechanistic aspects. Although the homogeneous catalyst is inexpensive with high catalytic efficiency and efficient at mild reaction conditions, there exists the main difficulty of its separation from the product mixture and its reusability. In order to improve the recyclability of the catalyst, researchers have begun to develop heterogeneous catalysts, mainly including metal oxides28, molecular sieves29, supported catalysts30-33 and carbon nanotube-ionic liquids based catalysts34-36. Bhanage et al.37 studied the catalytic performance of metal oxide catalyzed ring-opening addition reaction. The results showed that the catalytic performance of MgO and La2O3 was better than ZrO2, CaO, ZnO and CeO2. For a reaction temperature of 150°C, CO2 pressure of 8 MPa and a reaction time of 15 h, the MgO and La2O3 catalyzed reaction yielded an epoxide conversion rate of up to 34.9% and 73% respectively. The usage of an organic base or quaternary ammonium salt as a catalyst with a molecular sieve, the catalytic activity of the catalyst was remarkably improved. For instance, Srivastava et al.38 used DMAP as a co-catalyst to study the catalytic activity of titanium silicalite. Over a CO2 pressure of 0.69 MPa at 160°C, the yield of the cyclic carbonate obtained was found to be 94%. Xiong et al.39 studied the ring-opening addition reaction of CO2 with epoxide 4


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using tributyl phosphonium salt on a highly crosslinked chloromethylated polystyrene as catalyst. The results showed that a high cyclic carbonate yield of 98.6% with 100% selectivity were achieved under a pressure of 5 MPa CO2 at 150 °C for 6 h. Han et al. 40

successfully loaded the imidazolium ionic liquid onto multi-walled carbon

nanotubes and used it as a highly efficient heterogeneous catalyst for the synthesis of various cyclic carbonates by ring-opening addition reaction. The use of oxidized multi-walled carbon nanotubes as a support material significantly improved the catalytic performance of immobilized ionic liquids compared to conventional porous SiO2 and polymeric supports. The use of heterogeneous catalysts greatly eases the limitations of recyclability. However, most of the reported supports are non-renewable and suffers the issue of toxicity. In addition, the demand of most commonly used metals is decreasing considerably together with their low recycling rates. Therefore, for a sustainable development strategy, it is necessary to develop green, renewable and alternative metal free catalysts for environmental applications. Kleij and Detrembleur et al.41-43 reviewed the use of organocatalysts for the ring-opening addition reaction. The organocatalysts are cheap, readily available and non-toxic compounds with high chemical stability towards moisture and air. Additionally, they were effectively participates in the reaction to increase process sustainability by efficient energy use with the high conversion of substrate materials, avoiding the use of solvents and metals, and increasing the reaction efficiency. Cellulose is the most abundant member of biopolymers on the planet and it is a renewable resource. Cellulose macromolecules are characterized by well-defined chain length and extensive network of ordered intermolecular and intramolecular hydrogen bonds44-45. In addition to its unique structure, biocompatibility, non-toxicity, reactivity and low cost, cellulose can be used to produce renewable biopolymers of functional materials to ensure sustainability46. In addition, the cellulose surface has a large number of highly active hydroxyl groups, which are quite prone to chemically modify, providing almost inexhaustible supply requirements for the development of a greener support for catalytic organo-frameworks47. Cellulose as a hydrogen bond 5



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donor has been reported in many works48-50. Park et al.48 synthesized quaternized ethylenediamine cellulose by a microwave irradiation method and successfully used for the cycloaddition of CO2 with epoxide under the solvent-free conditions, with excellent thermal and humidity stability. Han et al.49-50 also reported the use of cellulose coupled with KI and 1, 8-diazabicyclo [5.4.0]-undec-7-ene (DBU) for the synthesis of cyclic carbonates by cycloaddition of CO2 with epoxides. They stated that the presence of vicinal hydroxyl groups in cellulose is critical for CO2 conversion with the synergy of the coupled material. In this paper, we report on the synthesis, characterization and catalytic application of metal-free Schiff base complex anchored on cellulose in the ring-opening addition reaction of CO2 with epoxide in solvent-free condition for the first time. The Schiff base complexes were reported several advantages such as simple preparation, insensitivity to water and air, easy modification and the phenolic -OH group from the Schiff base also actively part in the activation of epoxide by hydrogen bonding42-43,51-53. Moreover, the prepared materials were characterized and the reaction parameters were optimized. The synergistic effects of hydroxyl, phenolic -OH and Lewis basic (imine) sites in the catalyst have a strong effect on the adsorption and activation of reactant molecules for the cycloaddition reaction together with the enhanced role of nucleophilic group (Br-) in the co-catalyst.

2. Experimental 2.1 Materials and methods Microcrystalline cellulose (MCC, < 25 μm, Aladdin), propylene oxide (PO, 99%, Aladdin), ethylene oxide (99.5%, Aladdin), epichlorohydrin (AR, Aladdin), 1,2-butylene oxide(>99%, Aladdin), styrene oxide(98%, Aladdin), epoxycyclohexane (98%, Aladdin), N,N-dimethylformamide (DMF, 99.5%, Aladdin), chlorosulfoxide (99%, Aladdin) and diethylenetriamine (99%, Aladdin) were used directly. The other reagents

such

as

tetrabutylammonium

(triphenylphosphoranylidene)

ammonium

bromide chloride

6


(TBAB,

99%),

(PPNCl,

bis 96%),

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4-Dimethylaminopyridine (DMAP, 99%), ammonia (25%-28%), salicylaldehyde (98%) and ethanol (99.5%), were obtained from other commercial sources, all of which are analytical grade and no further purification was made before use. The CO2 gas (> 99.99%) was purchased from Kunming Meser gas co., LTD., China. 2.2 Synthesis of cellulose-based Schiff base complex (Cell-H2L) 2.2.1 Preparation of Chlorocellulose (Cl-cell) The measured quantities of microcrystalline cellulose (MCC, 30.86 mmol, 5 g) and N, N-dimethylformamide (DMF, 129.22 mmol, 100 ml) were mixed in a 250 ml three-necked flask, and the mixture was heated to 80°C. Next, thionyl chloride (196.19 mmol, 17 ml) was slowly added and the temperature of the reaction mixture was strictly controlled below 90°C. After 2.5 h of reaction, the heating was stopped, and the resultant product was cooled to room temperature with stirring, washed with deionized water followed by 3% ammonia in water until it becomes neutral and then the sample was filtered. It was then dried in the vacuum oven at 60°C for 12 h to obtain chlorinated cellulose (Cl-cell)54. 2.2.2 Preparation of cellulose-based Schiff base complex (Cell-H2L) In a typical procedure, the required amount of salicylaldehyde (150 mmol, 15.65 ml) and diethylenetriamine (75 mmol, 8.07 ml) were mixed in a 250 ml round bottom flask containing 100 ml of ethanol. The mixture was refluxed at 75°C for 24 h. The reaction mixture was then cooled at room temperature, and the solvent was evaporated in a rotary evaporator to obtain a concentrated orange coloured liquid product. The as-obtained Schiff base complex (H2L) was then dried in a vacuum oven at 60ºC. In the next step, the weighed amount of previously prepared Cl-cell (10 mmol, 1.8 g) and H2L (3.11 g, 10 mmol) were added to a 250 ml three-necked round bottom flask (1:1 mol ratio) containing 100 ml of ethanol, and the mixture was stirred with heating at 70°C for 6 hours and finally washed with ethanol. The pale-yellow coloured solid sample was then collected by filtration, washed with water to remove the impurities and which was dried in a vacuum oven to obtain the final catalyst. A schematic representation of the synthesis route is shown in scheme 1. 7



Scheme 1. Schematic representation of the synthesis of chlorinated cellulose support (Cl-cell) and metal-free heterogeneous catalyst (Cell-H2L).

2.3 Characterization of the prepared samples The FTIR spectra of the samples were recorded in a Bruker 70 vertex instrument in the wavenumber range of 400-4000 cm-1 with anhydrous KBr pellet method. The solid-state NMR spectra of samples were obtained on a Bruker Avance DPX300 NMR spectrometer at room temperature. The surface chemistry analysis was performed using X-ray photoelectron spectroscopy (XPS, Thermo Fisher ESCALAB 250Xi) equipped with Al Kα radiation as the monochromatic source and the peaks were calibrated using binding energy of C1s peak at 284.6 eV. The elemental analysis was carried out using a Vario EL III elemental analyzer (Elementar, Germany) to determine the C, H, and N content of the samples. The specific surface area and pore parameters of the materials were measured by N2 physisorption analysis at -196℃ using a BET specific surface area analyzer (3H-2000BET-A). The samples were degassed at 60ºC for 12 h in vacuum prior to the BET analysis. The morphological characteristics of the samples were investigated through a scanning electron 8


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microscope (SEM, LeoSupra 50VP), operated at an accelerating voltage of 20.0 kV. The thermogravimetric analysis was carried out in a thermal analyzer (TG, NETZSCH STA449F3) from room temperature to 600°C under N2 atmosphere with a flow rate of 50 ml/min. 2.4 Catalytic performance of the samples The catalytic performance of the prepared catalysts was carried out in a Teflon lined stainless-steel autoclave with a total capacity of 100 ml in the batch mode. The reactant species and catalysts were stirred by means of magnetons. In a typical experiment, the molar ratio of Cell-H2L to propylene oxide (PO) was kept 1:250 (~0.25 g for Cell-H2L and ~10 ml for PO) and the molar ratio of Cell-H2L to TBAB (co-catalyst) was kept 1:0.5 (about 0.09 g of TBAB). All of these reactant and catalyst species were added into Teflon lined stainless steel autoclave, closed tightly and sealed. Then, high-purity CO2 was introduced into the autoclave and sequentially discharged few times to remove the impurities and other kinds of trapped gases inside the reactor. Finally, the reactor was pressurized to the required CO2 pressure (1 MPa) and the reactor was heated to desired reaction temperature (70ºC). Once the set reactor temperature has been attained, the reaction was started for a specific period of time with a stirring rate of 280 rpm/min. After the completion of reaction, the autoclave was cooled to 0ºC using an ice bath, and the remaining CO2 in the autoclave was slowly released. The reaction mixture was then collected manually and the catalyst was separated from the reaction mixture by simple filtration. The product sample was then characterized by using 1H NMR analysis. For this analysis, ~50 μml of product was taken in a NMR tube and mixed with CDCl3 as a solvent with TMS as internal standard. The product was detected by 1H MNR spectrum (NMR, Bruker Advance III HD 600) at ambient temperature. The conversion of propylene oxide and the yield of cyclic carbonate were calculated using the peak integral method as reported previously55-57. For the reusability studies, the used catalyst from the reaction medium

was

separated by filtration, washed with

ethanol followed by

dichloromethane and then dried in the vacuum oven at 60℃ for 2 h and then used for 9



next catalytic run. Same experimental conditions were used for the recyclability experiments and in each run fresh TBAB was added. 3. Results and discussion 3.1 Material characterization FTIR spectra of the MCC, Cl-cell and Cell-H2L are presented in Figure 1. Compared to microcrystalline cellulose (Figure 1(a)), two well resolved transmission bands were observed in the sample treated with thionyl chloride (Figure 1(b)) which is located at 752 cm-1 and 709 cm-1. These two bands were attributed to the stretching and bending vibration of the carbon-chloride bond (C-Cl)54. Moreover, the characteristic transmission band of primary hydroxyl group at 1100 cm-1 in the raw cellulose was significantly weakened after chlorination as shown. It indicates that the hydroxyl group at C6 position of microcrystalline cellulose was successfully chlorinated. The chlorination is highly desired for the utilization cellulose as a support material in the heterogeneous catalysis. The reason behind for this chlorination is according to the reactivity of the substituted atom, as chloride group exhibits higher reactivity than the original hydroxyl group in the cellulose. This further ensures the possibility of next loading or anchoring of ligands in cellulose54,58. Figure 1(c) shows the FTIR spectra of the Schiff base complex (H2L). The characteristic transmission bands located at 3324 cm-1, 1630 cm-1 and 1037 cm-1 were attributed to the stretching vibrations of the N-H bond, C=N bond and C-N bond respectively. It can be seen from Figure 1(d) that the transmission band of C-Cl bond was completely removed after anchoring of Schiff base onto the chlorinated cellulose, whereas the transmission bands for C=N bond at 1630 cm-1 and C-N bond at 1037 cm-1 was observed to be comparatively intense. It indicates that the Schiff base complex is successfully anchored onto the chlorinated cellulose.

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Figure 1. FT-IR spectra of the samples: (a) MCC, (b) Cl-cell, (c) H2L and (d) Cell-H2L.

In order to study the ultrastructural features and their changes during the surface modification, the microcrystalline cellulose, chlorinated cellulose and Cell-H2L were characterized by 13C solid-state nuclear magnetic resonance spectroscopy. As shown in Figure 2(a), the chemical shifts at 105 ppm and 88 ppm are characteristics of the cellulosic carbon at C1 and C4 positions respectively. The chemical shifts in between 72-75 ppm could be due to the presence of C2, C3 and C5 positions as they are in similar chemical environment59-60. C6 is an important carbon atom that is attached to the ring and bonded to the hydroxyl group at a minimum chemical shift distribution of 65 ppm. In addition, the disordered peaks appeared at 85 ppm and 62 ppm in the microcrystalline cellulose are attributed to the chaining of cellulose61-62. Compared to microcrystalline cellulose, the chemical shift of C6 in the chlorinated cellulose is shown in Figure 2(b) and it exhibited a downward shift from 65 ppm to 44 ppm, 11



indicating efficient synthesis of chlorocellulose60. As shown in Figure 2(c), the cellulose modified by the Schiff base ligand undergone a significant structural change. Due to the presence of imine groups, the C9 peak is located at a higher chemical shift values to create a cross-linking process54. The chemical shift signal of C6 is found to be quite closer to C7 and C8 positions. Moreover, the carbon chemical shifts of the benzene ring were positioned at higher chemical shifts than in the carbons of the cellulosic carbon. Thus, it is clear that the chlorinated cellulose is successfully complexed with the Schiff base ligand.

Figure 2. Solid-state 13C NMR spectra of (a) MCC, (b) Cl-cell, (c) Cell-H2L.

To confirm the surface characteristics and chemical composition of the cellulose supported Schiff base complex, XPS analysis was performed. As shown in the wide 12


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scan spectra (Figure 3(a)), the catalyst exhibited only the peaks for C 1s, N 1s and O 1s as main elements and confirmed that the sample is free from any metal species. Moreover, no peaks related to chlorine were detected in the catalyst. It indicates the absence of chlorine coordination in the Schiff base complex and therefore, the formation of a quarternary ammonium salt can be discarded. The deconvoluted narrow scan spectrum of C1s is shown in Figure 3(b). The presence four deconvoluted peaks at binding energies of 284.4 eV, 285.68 eV, 286.58 eV and 288.09 eV were confirmed the existence of C-C/C=C, C-N, C-O and C=N functional groups in the catalyst63. This is highly consistent with the FTIR results shown in Figure 1. There are two deconvoluted peaks were observed in the narrow scan spectrum of O 1s that were found to be located at the binding energies of 531.46 eV and 532.47 eV respectively, as shown in Figure 3(c). These peaks were related to the C-O and O-H groups in the catalyst as indicated in the FTIR spectra64. The narrow scan XPS spectrum of N 1s shown in Figure 3(d) further confirmed the presence of C=N, C-N groups as confirmed by the peaks at the binding energies of 398.9 eV and 400.63 eV respectively65. These results further validate the successful formation Cell-H2L.

13



Figure 3. XPS analysis of the Cell-H2L: (a) survey scan spectrum and (b-d) narrow scan spectrum of C 1s (b), O 1s (c) and N 1s (d).

Table S1 shows the elemental composition of MCC, Cl-cell and Cell-H2L. The results show that the elemental composition of Cell-H2L is significantly different from that of MCC and Cl-cell. There is an entering of N element and the content of C and N were significantly increased in the sample. It can be also seen from the Table S1 that the percentage of C, H, and N elements measured by the elemental analysis is basically consistent with their theoretical percent. It further indicates that the Schiff base complex is entirely replaced the chlorine substituents on cellulose. Figure 4 shows the SEM images of the cellulose, Cl-cell, and Cell-H2L. It can be seen that the cellulose possesses a micro-flake like morphology with smooth surface. The size of the flakes varied greatly. However, after the thionyl chloride treatment of 14


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cellulose, it exhibited a drastic change in the surface morphology. A dense network of fiber-like nanostructure was seen in the sample with a porous texture66. This could be due to the surface bleaching of cellulose after clorination. This porous surface structure was found to be well maintained in the ligand anchored cellulosic catalyst as shown in Figure 4(c). Because of the presence of porous surface structure in the sample, the reactant molecules can be easily diffused through the pores for a better catalytic performance via increased active contact sites67.

Figure 4. SEM images of the prepared samples: (a) MCC, (b) Cl-cell, (c) Cell-H2L.

In order to evaluate the specific surface area and pore parameters of the samples, Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) method was used. The results had shown that the specific surface area of raw cellulose is 4.9 m2/g with an average pore diameter distribution of ~19 nm. After SOCl2 treatment, the specific surface area of the cellulose was drastically increased to 11.5 m2/g with a reduction in its pore size (9.58 nm). It could be due to the influence of chlorination, which is consistent with the SEM results shown in Figure 4. Moreover, compared to cellulose and its chlorinated form, the Cell-H2L has higher specific surface area of 20.6 m2/gcat, whereas its pore diameter remained same as that of Cl-cell. The average pore diameter was measured to be 9.17 nm. The increased specific surface area of the metal-free heterogeneous Cell-H2L catalyst exposes more hydrogen bond demanding hydroxyl groups and Lewis basic active groups (C=N) in it, which could be expect to increase 15



the collision and adsorption of reactant molecules on the catalyst interface. Figure 5 shows the TGA-DTA curves of the as-prepared heterogenous catalyst. There is a negligible amount of mass loss was noticed in between 30-120°C (3.6%), which could be attributed to the loss of any adsorbed gas or water molecules from the catalyst. However, the main weight loss observed in the region of 237-450°C, as confirmed in the DTG curve, with a total weight reduction of 73.3 % could be ascribed to the thermal degradation of the cellulose and Schiff base ligand68-69.

Figure 5. TGA/DTG curves of the Cell-H2L.

3.2 Catalytic activity of the prepared samples After the evident structural characterization of the Cell-H2L, it was successfully used as a metal-free heterogeneous catalyst for the solvent-free synthesis of cyclic carbonate in the ring-opening addition reaction of CO2 with epoxide. Initially, propylene oxide was used as model epoxide. Table S2 shows the results obtained in the preliminary catalytic experiments of the reaction with different reaction conditions such as the impact of a catalyst and co-catalysts under same reaction conditions. The 16


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data in Table S2 shows that, in the absence of catalyst and with MCC, Cl-cell, there is no formation of propylene carbonate (Table S2, entry 1, 2, 3). Even though there is a high possibility for the adsorption of epoxide molecules due to the presence of hydroxyl groups in the cellulosic structure, the catalytic inactiveness for epoxidation could be due to the absence of Lewis basic active sites. However, when the reaction was carried out with Schiff base complex (H2L), physically mixed Schiff base complex and cellulose (MCC/H2L), and cellulose-based Schiff base catalyst, the results are satisfactory (Table S2, entries 4, 5 and 6). This could be attributed to the fact that the sample contains not only an OH groups to provide a hydrogen bond donor to the epoxide but also has Lewis basic sites for activating the CO2 molecule. The presence of phenolic -OH groups also effectively participates in the epoxide activation as reported previously70. The catalytic performance of these catalytic materials followed the order of Cell-H2L > MCC/H2L > H2L. The reason for the lowest catalytic performance of H2L is that the cellulose contains a hydrogen bond donor, which makes the epoxide easier to open as reported by Park and Zhang et al.48,50. Although the catalytic performance of MCC/H2L is comparable to that of Cell-H2L, MCC/H2L has the disadvantage of its reusability as it is considered as a homogeneous catalyst. The effect of three different co-catalysts was further studied in the reaction without adding the Cell-H2L catalyst. The results in Table S2 show that all of the co-catalysts have negligible catalytic activity (Table S2, entries 7, 8 and 9). Taking into the economic benefits and reactivity, we had tested the TBAB co-catalyzed reaction with the Cell-H2L catalyst. The results showed that the catalytic efficiency of the reaction in this case was higher than that of the same when the reaction performed with Cell-H2L and TBAB alone (Table S2, entry 10). Their synergistic role in the ring opening addition reaction of CO2 with epoxide is discussed together with the reaction mechanism. The product obtained by the cyclic addition of CO2 with propylene oxide was characterized by FT-IR. As shown in Figure S1, two intense transmission bands were 17



observed at 1783 cm -1 and 1176 cm-1. These bands are attributed to the stretching vibration of the C=O and C-O bonds in propylene carbonate respectively71. Therefore, the formation of cyclic carbonate in the catalytic reaction can be confirmed. To confirm the structure of the cyclic carbonate, 1H nuclear magnetic resonance spectra of the reactant was recorded and the results are shown in Figure S3. The chemical shift signals for the propylene carbonate are given as follows: CH3 (methyl): 1.45-1.50 (t, 1H), CH2 (methylene): 4.03-4.07 (t, 1H) and 4.57-4.61 (t, 1H), CH (methine): 4.87-4.92 (dd, 1H). It completely validates the formation of propylene carbonate by the ring-opening addition of CO2 with PO55,72. The reaction conditions such as the reaction temperature, CO2 pressure and reaction time were further varied to optimize their effect on the reaction efficiency. The yield and selectivity of the propylene carbonate at different reaction conditions are shown in Figure 6. The influence of reaction temperature is firstly studied and the result is shown in Figure 6(a). The reaction temperature had a significant effect in the present catalytic reaction. As seen, when the reaction temperature increased from 60°C to 100°C, the yield of PC increased from 42.6% to 71.5% as expected. This could be due to the endothermic nature of the reaction73. Therefore, for the next set of studies, 100°C was selected for the CO2-propylene oxide ring-opening addition reaction. The effect of CO2 pressure on the catalytic performance is shown in Figure 6(b). The increase of CO2 pressure from 0.5 MPa to 3 MPa, resulted in a drastic increase of the yield of PC, whereas the further increase of CO2 pressure to 4 MPa, a negative effect was noticed. Similar results were previously reported for other kind of catalysts. It could be attributed to the different concentration gradients of the reactants in the reaction system. Under the condition of high CO2 pressure, the concentration of liquid PO in the vicinity of the catalyst gets lowered, which is not good for an efficient catalyst reaction as the interaction between PO and Cell-H2L gets significantly weakened for the better conversion under the applied conditions9,74. Therefore 3 MPa is the optimized pressure that has been used in the synthesis of cyclic carbonate. Figure 6(c) shows the trend of yield and selectivity of PC as a 18


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function of time. The yield was found to be increased with time for a period of 3 to 6 h. A highest yield of 98.7% was noticed for a period of 6 h reaction with selectivity close to 100%. It remained almost same for the further increase of reaction time.

Figure 6. Effect of reaction parameters on the reaction efficiency: (a) Effect of temperature [Catalyst 0.57 mmol, TBAB 0.28 mmol, 1 MPa CO2, 4 h], (b) Effect of CO2 pressure [Catalyst 0.57 mmol, TBAB 0.28 mmol, 100°C, 4 h], (c) Effect of reaction time [Catalyst 0.57 mmol, TBAB 0.28 mmol, 100°C, 3 MPa CO2]. To demonstrate the efficiency of the prepared catalyst, a comparison of the catalytic activities of different catalytic systems is summarized in Table 1. It can be seen that the Cell-H2L/TBAB catalytic system processes competitive activity with some of the reported efficient catalysts. The present catalyst has several advantages such as simple preparation, small catalyst loading, mild reaction conditions and good catalytic recyclability compared with the reported catalytic systems. This further 19



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indicates that the Cell-H2L/TBAB catalytic system is a potential candidate in the chemical conversion of CO2 into cyclic carbonates by ring-opening addition reaction.

Table 1. Comparison of the different catalytic systems for cycloaddition of CO2 with PO

Entry

Catalysts

T

P

Time

Yield

(℃)

(MPa)

(h)

(%)

Reference

1

HbetI

140

8

8

98

75

2

p-methoxyphenol/DMAP

120

3.57

48

89

76

3

DBU/MCC

120

2

2

90

50

4

HbimCl-NbCl5/HCMC

130

1.5

3

98.1

77

5

CS-N+Me3Cl-

160

4

6

98

78

6

bis-β-CD 1a/TBAB

120

4

2

94

79

7

Lignin/KI

140

2

12

93

80

8

CS-EMImBr

120

2

4

96

9

9

Cell-H2L/TBAB

100

3

6

99

this work

Under optimized reaction conditions, i.e., at a reaction temperature of 100ºC, CO2 pressure of 3.0 MPa and a reaction time of 6 h (except entry 1 (1 MPa) and entry 3 (2 MPa)), the ring opening addition reaction was carried with a set of terminal and internal epoxides. The results are summarized in Table 2. As shown in Table 2 (entries 1-5), the sample showed higher catalytic activity specifically for terminal epoxides either containing an electron withdrawing or donating group in it. However, for cyclohexene oxide (entry 6), no product formation was noticed for a period of 6 hours. 20


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Therefore, the reaction time was further extended to 20 h. However, a trace amount of the corresponding cyclic carbonate was formed. The inactiveness could be attributed to its high steric hindrance and intrinsic inertness as reported previously13-14.

Table 2. Comparison of the catalytic activity of the catalyst with different epoxidesa.

Entry

Substrate

Time

Product

(h) 1

O

3

O

O

Yield

Selectivity

(%)

(%)

>99

>99

98.7

>99

99

>99

60

>99

74.5

>99

Trace

n.d.

O O

O

2

O

6

H3C

O

H3C

O

3

O Cl

6

O

O

Cl

O

4

O H 3C

6

O

O

H3C O O

O

5

6

O

O O

6

a

O

O

20

Reaction conditions: amount of substrate (142.9 mmol), catalyst (0.57 mmol), TBAB

(0.28 mmol), 100°C, CO2 pressure 3 MPa (except entry 1 (1 MPa) and entry 3 (2 21



MPa)) and 280 rpm stirring rate. A possible reaction mechanism for the synthesis of cyclic carbonates from CO2 and epoxide over Cell-H2L catalyst using TBAB co-catalyst has been proposed and a schematic illustration is shown in Figure 7. The reaction begins with the activation of epoxide. First, the hydroxyl groups on the cellulosic support forms intra-molecular hydrogen bond with the oxygen of epoxide to achieve its activation. This makes the epoxide quite easier to open74. The phenolic -OH group from the Schiff base part of the Cell-H2L also actively part in the activation of epoxide by hydrogen bonding70. At the same time, the nucleophile from the co-catalyst (Br-) attacks the sterically hindered β-C atom of the epoxide20,81. This is followed by the adsorption and activation of CO2 on the Lewis basic sites (imine) of the catalyst, especially located in the ligand, at its attachment with the cellulose. During this stage, the β-C-O bond of the epoxide could be broken and a ring opening is resulted. After ring opening, an oxygen anion intermediate containing a β-C-Br bond is formed as shown in step II. In the next step, the CO2 activated on the Lewis basic site inserts into the oxygen anion intermediate containing β-C-Br bond (step III). This is followed by the loop close process of the reaction and which is preceded through the intramolecular nucleophilic attack resulting in the formation of cyclic carbonate, and resultant vacant active sites were further used in the next catalytic process. Thus, the synergistic effects of OH groups and Lewis basic sites are of great importance in the reaction3,82-83.

22


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Figure 7. Schematic representation of the possible reaction mechanism.

The interaction of the Schiff base ligand on CO2/PO system by density functional theory (DFT) was further studied. The simulation results show that the phenolic -OH groups in the Schiff base complex delivers a hydrogen bond with PO at a length of 1.787 Å (Figure 8). After the hydrogen bond formation between PO and phenolic -OH, the length of the C-O bonds in epoxide increased from 1.435 Å to 1.451 Å and 1.434 Å to 1.445 Å, respectively. It makes the ring opening easier. Moreover, the DFT simulation results show that after interacting with H2L, the linear CO2 bond angle was changed from 180°to 177°. It results in polarization and the CO2 gets activated.

23



Figure 8. DFT study of the Schiff base complex (H2L) interaction with propylene oxide and CO2.

In order to test the recyclability of Cell-H2L, the ring-opening addition reaction was carried out with PO as a substrate at 100°C under a CO2 pressure of 3 MPa for a period of 6 h. As shown in Figure 9, after five continual runs, the yield and selectivity of PC was not changed considerably. However, the negligible decrease in activity per run could be attributed to the loss of very small amount of catalyst in successive cycles. The structural stability of the reused sample was studied using FTIR spectroscopy and the spectra are shown in Figure 10. It shows that the characteristic transmission bands of the fresh sample, i.e., at ~1630 cm-1 (C=N) and ~1037cm-1 (C-N) were not disturbed even after 5 cycles of reaction. However, some of the additional bands were also noticed which could be assigned to the influence of the adsorbed products. As it is quite difficult to separate the catalyst from the products completely after five cycles, the bands at 1783 cm-1 and 1176 cm-1 could be attributed to the C=O and C-O bonds in the propylene carbonate. It further indicates the high 24


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catalytic stability of the catalyst.

Figure 9. Reusability performance of the Cell-H2L catalyst.

Figure 10. FT-IR spectral variation of the catalyst (Cell-H2L) after 5 cycles. 4. Conclusions In summary, a non-metal Schiff base complex anchored on cellulose was 25



Page 26 of 35

prepared by a facile technique and it was used for the synthesis of cyclic carbonate by the ring-opening addition of CO2 with epoxide in a solvent-free condition. The prepared samples were completely characterized for their structural characterization using several analytical techniques of FTIR, SEM, XPS, Solid-state

13

C NMR and

TGA. The cellulose-based Schiff base complex together with a nucleophilic agent such as TBAB (co-catalyst) resulted in a high yield of the desired cyclic carbonate with >99% selectivity. The hydroxyl groups from cellulose and phenolic –OH groups from ligand and Lewis basic sites in the catalyst itself played an important role in the adsorption and activation of the reactant molecules for an efficient reaction with high selectivity. The optimization studies had shown that a maximum yield of 98.7% with ~100% selectivity was observed at the conditions of a reaction temperature of 100°C, CO2 pressure of 3 MPa and a reaction period of 6 h. Furthermore, the metal-free cellulose-based Schiff base complex was successfully recycled by a simple filtration method and reused nearly five times without any significant loss its catalytic activity. As the catalyst is free from metals, containing natural support, heterogeneous, environmentally friendly, and showing high activity in a solvent free reaction, it is recommended to use in other related catalysis and also in industries. Supporting Information Elemental analysis and initial catalyst screening (Tables S1 & S2), FT-IR spectra of propylene oxide and propylene carbonate (Figure S1), 1H NMR spectra of different epoxides and cyclic carbonates (Figure S2-S7) and

1

H NMR data for cyclic

carbonates. This information is available free of charge via the Internet at http://pubs.acs.org/. Acknowledgments This work was financially supported by the National Natural Science Foundation of China (Grant Nos. 21566014 and 21766016). M Pudukudy acknowledges China Postdoctoral Science Foundation (Grant No. 2019M653845XB) and Postdoctoral Research Funding of Kunming University of Science and Technology (10988880). ORCID 26


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Manoj Pudukudy: 0000-0003-3370-4752 Qingming Jia: 0000-0002-1369-7156 Conflicts of Interest: none Refenences (1) Zhou, Q. S.; Peng, X. W.; Zhong, L. X.; Li, X. H.; Chua, W. T.; Sun, R. C. Xylan/DBU as an efficient and green catalyst for chemical fixation of CO2. Fuel Process. Technol. 2018, 176, 146-152. (2) Khattak, Z. A.; Younus, H. A.; Ahmad, N.; Yu, B.; Ullah, H.; Suleman, S.; Chughtai, A. H.; Moosavi, B.; Somboon, C.; Verpoort, F. Mono-and dinuclear organotin (IV) complexes for solvent free cycloaddition of CO2 to epoxides at ambient pressure. J. CO2 Util. 2018, 28, 313-318. (3) Samikannu, A.; Konwar, L. J.; Mäki-Arvela, P.; Mikkola, J.-P. Renewable N-doped active carbons as efficient catalysts for direct synthesis of cyclic carbonates from epoxides and CO 2. Appl. Catal., B 2019, 241, 41-51. (4) Chen, J.; Li, H.; Zhong, M.; Yang, Q. Hierarchical mesoporous organic polymer with an intercalated metal complex for the efficient synthesis of cyclic carbonates from flue gas. Green Chem. 2016, 18 (24), 6493-6500. (5) Kim, H. G.; Seo, B.; Lim, C. S. Metal- and halide-free catalysts supported on Silica and their applications to CO2 cycloaddition reactions. J. Ind. Eng. Chem. 2019, 75: 202-210. (6) Lu, X. B.; Darensbourg, D. J. Cobalt catalysts for the coupling of CO 2 and epoxides to provide polycarbonates and cyclic carbonates. Chem. Soc. Rev. 2012, 41 (4), 1462-1484. (7) North, M.; Pasquale, R.; Young, C. Synthesis of cyclic carbonates from epoxides and CO 2. Green Chem. 2010, 12 (9), 1514-1539. (8) Liu, Q.; Wu, L.; Jackstell, R.; Beller, M. Using carbon dioxide as a building block in organic synthesis. Nat. Commun. 2015, 6, 5933. (9) Sun, J.; Wang, J.; Cheng, W.; Zhang, J.; Li, X.; Zhang, S.; She, Y. Chitosan functionalized ionic liquid as a recyclable biopolymer-supported catalyst for cycloaddition of CO2. Green Chem. 2012, 14 (3), 654-660. (10) Ravi, S.; Puthiaraj, P.; Ahn, W. S. Cyclic carbonate synthesis from CO2 and epoxides over diamine-functionalized porous organic frameworks. J. CO2 Util. 2017, 21, 450-458.

27



(11) Chaugule, A. A.; Tamboli, A. H.; Kim, H. Ionic liquid as a catalyst for utilization of carbon dioxide to production of linear and cyclic carbonate. Fuel 2017, 200, 316-332. (12) Castro-Osma, J. A.; Lamb, K. J.; North, M. Cr (salophen) complex catalyzed cyclic carbonate synthesis at ambient temperature and pressure. ACS Catal. 2016, 6 (8), 5012-5025. (13) Lan, D. H.; Chen, L.; Au, C. T.; Yin, S. F. One-pot synthesized multi-functional graphene oxide as a water-tolerant and efficient metal-free heterogeneous catalyst for cycloaddition reaction. Carbon 2015, 93, 22-31. (14) Jiang, Y.; Li, J.; Jiang, P.; Li, Y.; Leng, Y. Amino acid-paired dipyridine polymer as efficient metal- and halogen-free heterogeneous catalysts for cycloaddition of CO2 and epoxides into cyclic carbonates. Catal. Commun. 2018, 111, 1-5. (15) Kamphuis, A. J.; Picchioni, F.; Pescarmona, P. P. CO2-fixation into cyclic and polymeric carbonates: principles and applications. Green Chem. 2019, 21 (3), 406-448. (16) Yadav, N.; Seidi, F.; Crespy, D.; D'Elia, V. Polymers Based on Cyclic Carbonates as Trait d'Union Between Polymer Chemistry and Sustainable CO2 Utilization. ChemSusChem 2019, 12 (4), 724-754. (17) Grignard, B.; Gennen, S.; Jérôme, C.; Kleij, A. W.; Detrembleur, C. Advances in the use of CO2 as a renewable feedstock for the synthesis of polymers. Chem. Soc. Rev. 2019, 48, 4466-4514. (18) Liu, D.; Li, G.; Liu, J.; Yi, Y. Organic-inorganic hybrid mesoporous titanium silica material as bi-functional heterogeneous catalyst for the CO2 cycloaddition. Fuel 2019, 244, 196-206. (19) Rodrigues, D. M.; Hunter, L. G.; Bernard, F. L.; Rojas, M. F.; Dalla Vecchia, F.; Einloft, S. Harnessing CO2 into carbonates using heterogeneous waste derivative cellulose-based poly (ionic liquids) as catalysts. Catal. Lett. 2019, 149 (3), 733-743. (20) Calo, V.; Nacci, A.; Monopoli, A.; Fanizzi, A. Cyclic carbonate formation from carbon dioxide and oxiranes in tetrabutylammonium halides as solvents and catalysts. Org. Lett. 2002, 4 (15), 2561-2563. (21) Rokicki, G.; Kuran, W.; Pogorzelska-Marciniak, B. Cyclic carbonates from carbon dioxide and oxiranes. Monatsh. Chem. 1984, 115 (2), 205-214. (22) Zhang, Y.; Chan, J. Y. G. Sustainable chemistry: imidazolium salts in biomass conversion and CO2 fixation. Energy Environ. Sci. 2010, 3 (4), 408-417.

28


Page 28 of 35

Page 29 of 35 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(23) Cho, H. C.; Lee, H. S.; Chun, J.; Lee, S. M.; Kim, H. J.; Son, S. U. Tubular microporous organic networks bearing imidazolium salts and their catalytic CO2 conversion to cyclic carbonates. Chem. Commun. 2011, 47 (3), 917-919. (24) North, M.; Quek, S. C.; Pridmore, N. E.; Whitwood, A. C.; Wu, X. Aluminum (salen) complexes as catalysts for the kinetic resolution of terminal epoxides via CO 2 coupling. ACS Catal. 2015, 5 (6), 3398-3402. (25) Martin, C.; Fiorani, G.; Kleij, A. W. Recent advances in the catalytic preparation of cyclic organic carbonates. ACS Catal.2015, 5 (2), 1353-1370. (26) Li, F.; Xiao, L.; Xia, C.; Hu, B. Chemical fixation of CO 2 with highly efficient ZnCl2/[BMIm] Br catalyst system. Tetrahedron Lett. 2004, 45 (45), 8307-8310. (27) Woo, W. H.; Hyun, K.; Kim, Y.; Ryu, J. Y.; Lee, J.; Kim, M.; Park, M. H.; Kim, Y. Highly Active Salen-Based Aluminum Catalyst for the Coupling of Carbon Dioxide with Epoxides at Ambient Temperature. Eur. J. Inorg. Chem. 2017, 2017 (45), 5372-5378. (28) Yamaguchi, K.; Ebitani, K.; Yoshida, T.; Yoshida, H.; Kaneda, K. Mg-Al mixed oxides as highly active acid-base catalysts for cycloaddition of carbon dioxide to epoxides. J. Am. Chem. Soc. 1999, 121 (18), 4526-4527. (29) Davis, R. J.; Doskocil, E. J.; Bordawekar, S. Structure/function relationships for basic zeolite catalysts containing occluded alkali species. Catal. Today 2000, 62 (2-3), 241-247. (30) Sankar, M.; Ajithkumar, T. G.; Sankar, G.; Manikandan, P. Supported imidazole as heterogeneous catalyst for the synthesis of cyclic carbonates from epoxides and CO 2. Catal. Commun. 2015, 59, 201-205. (31) Subramanian, S.; Park, J.; Byun, J.; Jung, Y.; Yavuz, C. T. Highly efficient catalytic cyclic carbonate formation by pyridyl salicylimines. ACS Appl. Mater. Interfaces 2018, 10 (11), 9478-9484. (32) Ghazali-Esfahani, S.; Song, H.; Păunescu, E.; Bobbink, F. D.; Liu, H.; Fei, Z.; Laurenczy, G.; Bagherzadeh, M.; Yan, N.; Dyson, P. J. Cycloaddition of CO 2 to epoxides catalyzed by imidazolium-based polymeric ionic liquids. Green Chem. 2013, 15 (6), 1584-1589. (33) Kohrt, C.; Werner, T. Recyclable bifunctional polystyrene and silica gel-supported organocatalyst for the coupling of CO2 with epoxides. ChemSusChem 2015, 8 (12), 2031-2034.

29



(34) Al-Garni, T.; Al-Jallal, N.; Aouissi, A. Synthesis of propylene carbonate from epoxide and CO2 catalyzed by carbon nanotubes supported Fe1.5PMo12O40. J. Chem. 2017, Article ID 5641604. (35) Jayakumar, S.; Li, H.; Chen, J.; Yang, Q. Cationic Zn–porphyrin polymer coated onto CNTs as a cooperative catalyst for the synthesis of cyclic carbonates. ACS Appl. Mater. Interfaces 2018, 10 (3), 2546-2555. (36) Baj, S.; Krawczyk, T.; Jasiak, K.; Siewniak, A.; Pawlyta, M. Catalytic coupling of epoxides and CO2 to cyclic carbonates by carbon nanotube-supported quaternary ammonium salts. Appl. Catal., A 2014, 488, 96-102. (37) Bhanage, B. M.; Fujita, S. i.; Ikushima, Y.; Arai, M. Synthesis of dimethyl carbonate and glycols from carbon dioxide, epoxides, and methanol using heterogeneous basic metal oxide catalysts with high activity and selectivity. Appl. Catal., A 2001, 219 (1-2), 259-266. (38) Srivastava, R.; Srinivas, D.; Ratnasamy, P. Synthesis of polycarbonate precursors over titanosilicate molecular sieves. Catal. Lett. 2003, 91 (1-2), 133-139. (39) Xiong, Y.; Bai, F.; Cui, Z.; Guo, N.; Wang, R. Cycloaddition reaction of carbon dioxide to epoxides catalyzed by polymer-supported quaternary phosphonium salts. J. Chem. 2013, Article ID 261378. (40) Han, L.; Li, H.; Choi, S. J.; Park, M. S.; Lee, S. M.; Kim, Y. J.; Park, D. W. Ionic liquids grafted on carbon nanotubes as highly efficient heterogeneous catalysts for the synthesis of cyclic carbonates. Appl. Catal., A 2012, 429, 67-72. (41) Fiorani, G.; Guo, W.; Kleij, A. W. Sustainable conversion of carbon dioxide: the advent of organocatalysis. Green Chem. 2015, 17 (3), 1375-1389. (42) Alves, M.; Grignard, B.; Méreau, R.; Jerome, C.; Tassaing, T.; Detrembleur, C. Organocatalyzed coupling of carbon dioxide with epoxides for the synthesis of cyclic carbonates: catalyst design and mechanistic studies. Catal. Sci. Technol. 2017, 7 (13), 2651-2684. (43) Buettner, H.; Longwitz, L.; Steinbauer, J.; Wulf, C.; Werner, T. Recent developments in the synthesis of cyclic carbonates from epoxides and CO2. Top. Curr. Chem. 2017, 375:50, 1-56. (44) Schnepp, Z. Biopolymers as a flexible resource for nanochemistry. Angew. Chem. Int. Ed. 2013, 52 (4), 1096-1108.

30


Page 30 of 35

Page 31 of 35 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(45) Zhi, Y.; Deng, X.; Ni, Y.; Zhao, W.; Jia, Q.; Shan, S. Cellulosic Cr (salen) complex as an efficient and recyclable catalyst for copolymerization of SO2 with epoxide. Carbohydr. Polym. 2018, 194, 170-176. (46) Deng, X.; Zhi, Y.; Shan, S.; Miao, Y.; Jia, Q.; Ni, Y. Effective and reusable microcrystalline cellulosic Salen complexes for epoxidation of alpha-pinene. Cellulose 2018, 25 (2), 1281-1289. (47) Roy, D.; Semsarilar, M.; Guthrie, J. T.; Perrier, S. Cellulose modification by polymer grafting: a review. Chem. Soc. Rev. 2009, 38 (7), 2046-2064. (48) Roshan, K. R.; Jose, T.; Kathalikkattil, A. C.; Kim, D. W.; Kim, B.; Park, D. W. Microwave synthesized quaternized celluloses for cyclic carbonate synthesis from carbon dioxide and epoxides. Appl. Catal., A 2013, 467, 17-25. (49) Liang, S.; Liu, H.; Jiang, T.; Song, J.; Yang, G.; Han, B. Highly efficient synthesis of cyclic carbonates from CO2 and epoxides over cellulose/KI. Chem. Commun. 2011, 47 (7), 2131-2133. (50) Sun, J.; Cheng, W.; Yang, Z.; Wang, J.; Xu, T.; Xin, J.; Zhang, S. Superbase/cellulose: an environmentally benign catalyst for chemical fixation of carbon dioxide into cyclic carbonates. Green Chem. 2014, 16 (6), 3071-3078. (51) Darensbourg, D. J. Making plastics from carbon dioxide: salen metal complexes as catalysts for the production of polycarbonates from epoxides and CO 2. Chem. Rev. 2007, 107 (6), 2388-2410. (52) Darensbourg, D.; Yeung, A. Kinetics of the (salen)Cr (Ⅲ)- and (salen)Co(Ⅲ)-catalyzed copolymerization of epoxides with CO2, and of the accompanying degradation reactions. Polym. Chem. 2015, 6 (7), 1103-1117. (53) Fazekas, E.; Nichol, G. S.; Shaver, M. P.; Garden, J. A. Stable Fe (Ⅲ) phenoxyimines as selective and robust CO2/epoxide coupling catalysts. Dalton Trans. 2018, 47 (37), 13106-13112. (54) da Silva Filho, E. C.; de Melo, J. C.; da Fonseca, M. G.; Airoldi, C. Cation removal using cellulose chemically modified by a Schiff base procedure applying green principles. J. Colloid Interface Sci. 2009, 340 (1), 8-15. (55) Cho, W.; Shin, M. S.; Hwang, S.; Kim, H.; Kim, M.; Kim, J. G.; Kim, Y. Tertiary amines: A new class of highly efficient organocatalysts for CO2 fixations. J. Ind. Eng. Chem. 2016, 44, 210-215.

31



Page 32 of 35

(56) Xiang, W.; Sun, Z.; Wu, Y.; He, L. N.; Liu, C. j. Enhanced cycloaddition of CO2 to epichlorohydrin over zeolitic imidazolate frameworks with mixed linkers under solventless and co-catalyst-free condition. Catal. Today 2019, https://doi.org/10.1016/j.cattod.2019.01.050. (57) Milani, J. L. S.; Meireles, A. M.; Cabral, B. N.; de Almeida Bezerra, W.; Martins, F. T.; da Silva Martins, D. C.; das Chagas, R. P. Highly active Mn (III) meso-tetrakis (2, 3-dichlorophenyl) porphyrin catalysts for the cycloaddition of CO2 with epoxides. J. CO2 Util. 2019, 30, 100-106. (58) Chen, Q.; Peng, C.; Xie, H.; kent Zhao, Z.; Bao, M. Cellulosic poly (ionic liquid) s: synthesis, characterization and application in the cycloaddition of CO2 to epoxides. RSC Adv. 2015, 5 (55), 44598-44603. (59) Zuckerstätter, G.; Terinte, N.; Sixta, H.; Schuster, K. C. Novel insight into cellulose supramolecular structure through

13

C CP-MAS NMR spectroscopy and paramagnetic relaxation

enhancement. Carbohydr. Polym. 2013, 93 (1), 122-128. (60) Silva Filho, E. C.; Lima, L. C.; Silva, F. C.; Sousa, K. S.; Fonseca, M. G.; Santana, S. A. Immobilization of ethylene sulfide in aminated cellulose for removal of the divalent cations. Carbohydr. Polym. 2013, 92 (2), 1203-1210. (61) Okushita, K.; Komatsu, T.; Chikayama, E.; Kikuchi, J. Statistical approach for solid-state NMR spectra of cellulose derived from a series of variable parameters. Polym. J. 2012, 44 (8), 895. (62) Idström, A.; Schantz, S.; Sundberg, J.; Chmelka, B. F.; Gatenholm, P.; Nordstierna, L.

13

C NMR

assignments of regenerated cellulose from solid-state 2D NMR spectroscopy. Carbohydr. Polym. 2016, 151, 480-487. (63) Tang, X.; Tang, P.; Liu, L. Preparation of tetraethylenepentamine modified magnetic graphene oxide for adsorption of dyes from aqueous solution. J. Bra. Chem. Soc. 2018, 29 (2), 334-342. (64) Yang, J.; Duan, J.; Zhang, L.; Lindman, B.; Edlund, H.; Norgren, M. Spherical nanocomposite particles prepared from mixed cellulose–chitosan solutions. Cellulose 2016, 23 (5), 3105-3115. (65) Jiao, C.; Zhang, Z.; Tao, J.; Zhang, D.; Chen, Y.; Lin, H. Synthesis of a poly (amidoxime-hydroxamic acid) cellulose derivative and its application in heavy metal ion removal. RSC Adv. 2017, 7 (44), 27787-27795.

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(66) da Silva Filho, E. C.; de Melo, J. C.; Airoldi, C. Preparation of ethylenediamine-anchored cellulose and determination of thermochemical data for the interaction between cations and basic centers at the solid/liquid interface. Carbohydr. Res. 2006, 341 (17), 2842-2850. (67) Pudukudy, M.; Yaakob, Z.; Mazuki, M. Z.; Takriff, M. S.; Jahaya, S. S. One-pot sol-gel synthesis of MgO nanoparticles supported nickel and iron catalysts for undiluted methane decomposition into COx free hydrogen and nanocarbon. Appl. Catal., B 2017, 218, 298-316. (68) Trache, D.; Hussin, M. H.; Chuin, C. T. H.; Sabar, S.; Fazita, M. N.; Taiwo, O. F.; Hassan, T.; Haafiz,

M.

M.

Microcrystalline

cellulose:

Isolation,

characterization

and

bio-composites

application—A review. Int. J. Biol. Macromol. 2016, 93, 789-804. (69) Trache, D.; Khimeche, K.; Donnot, A.; Benelmir, R. Thermal analysis of microcrystalline cellulose prepared from esparto grass. MATEC Web of Conferences 2013. 3. Article number: 01067-01608. (70) Yingcharoen, P.; Kongtes, C.; Arayachukiat, S.; Suvarnapunya, K.; Vummaleti, S. V.; Wannakao, S.; Cavallo, L.; Poater, A.; D'Elia, V. Assessing the pKa-Dependent Activity of Hydroxyl Hydrogen Bond Donors in the Organocatalyzed Cycloaddition of Carbon Dioxide to Epoxides: Experimental and Theoretical Study. Adv. Synth. Catal. 2019, 361 (2), 366-373. (71) Zhao, M.; Xiao, H.; Chen, S.; Hu, T.; Jia, J.; Wu, H. Temperature-tuned ferromagnetism in hydrogenated multilayer graphene. RSC Adv. 2018, 8 (24), 13148-13153. (72) Bhunia, S.; Molla, R. A.; Kumari, V.; Islam, S. M.; Bhaumik, A. Zn (Ⅱ) assisted synthesis of porous salen as an efficient heterogeneous scaffold for capture and conversion of CO 2. Chem. Commun. 2015, 51 (86), 15732-15735. (73) Peng, J.; Wang, S.; Yang, H. J.; Ban, B.; Wei, Z.; Wang, L.; Lei, B. Highly efficient fixation of carbon dioxide to cyclic carbonates with new multi-hydroxyl bis-(quaternary ammonium) ionic liquids as metal-free catalysts under mild conditions. Fuel 2018, 224, 481-488. (74) Cheng, W.; Chen, X.; Sun, J.; Wang, J.; Zhang, S. SBA-15 supported triazolium-based ionic liquids as highly efficient and recyclable catalysts for fixation of CO 2 with epoxides. Catal. Today 2013, 200, 117-124.

33



(75) Zhou, Y.; Hu, S.; Ma, X.; Liang, S.; Jiang, T.; Han, B. Synthesis of cyclic carbonates from carbon dioxide and epoxides over betaine-based catalysts. J. Mol. Catal. A: Chem. 2008, 284 (1-2), 52-57. (76) Shen, Y. M.; Duan, W. L.; Shi, M. Chemical fixation of carbon dioxide Co-catalyzed by a combination of schiff bases or phenols and organic bases. Eur. J. Org. Chem. 2004, 2004 (14), 3080-3089. (77) Wu, X.; Wang, M.; Xie, Y.; Chen, C.; Li, K.; Yuan, M.; Zhao, X.; Hou, Z. Carboxymethyl cellulose supported ionic liquid as a heterogeneous catalyst for the cycloaddition of CO 2 to cyclic carbonate. Appl. Catal., A 2016, 519, 146-154. (78) Zhao, Y.; Tian, J. S.; Qi, X. H.; Han, Z.-N.; Zhuang, Y.-Y.; He, L.-N. Quaternary ammonium salt-functionalized chitosan: An easily recyclable catalyst for efficient synthesis of cyclic carbonates from epoxides and carbon dioxide. J. Mol. Catal. A: Chem. 2007, 271 (1-2), 284-289. (79) Peng, J.; Wang, S.; Yang, H.-J.; Ban, B.; Wei, Z.; Wang, L.; Bo, L. Chemical fixation of CO2 to cyclic carbonate catalyzed by new environmental-friendly bifunctional bis-β-cyclodextrin derivatives. Catal. Today 2019, 330, 76-84. (80) Wu, Z.; Xie, H.; Yu, X.; Liu, E. Lignin-based green catalyst for the chemical fixation of carbon dioxide with epoxides to form cyclic carbonates under solvent-free conditions. ChemCatChem 2013, 5 (6), 1328-1333. (81) Sun, J.; Fujita, S. i.; Bhanage, B. M.; Arai, M. One-pot synthesis of styrene carbonate from styrene in tetrabutylammonium bromide. Catal. Today 2004, 93, 383-388. (82) Biswas, S.; Khatun, R.; Sengupta, M.; Islam, S. M. Polystyrene supported Zinc complex as an efficient catalyst for cyclic carbonate formation via CO 2 fixation under atmospheric pressure and organic carbamates production. Mol. Catal. 2018, 452, 129-137. (83) North, M.; Pasquale, R. Mechanism of cyclic carbonate synthesis from epoxides and CO 2. Angew. Chem. Int. Ed. 2009, 48 (16), 2946-2948.

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A non-metal Schiff-base complex anchored cellulose as a novel and

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