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Ionic liquids (ILs) have shown predominant catalytic activity in the field of catalytic conversion of CO2. Unfortunately, ILs catalysts can be only used in kettle catalysis as homogeneous systems, which suffered from the difficulty in product purification and catalysts recycling so affect their industrial application. In this work, a series of comp...
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Various types of mesoporous silica were used as carriers to synthesize a series of immobilized imidazolium-based ionic liquids. Their activity was tested in the synthesis of styrene carbonate from CO2 and styrene. This is one-pot process, whereby two stages are carried out in one reactor and there is no need to isolate the intermediate product, epo...
A series of eight Mn(III)-porphyrin (MnP) complexes with electron-withdrawing substituents at the meso and/or β-pyrrole positions of the macrocycle were designed to uncover electronic and structural aspects of MnP catalytic activity in the cycloaddition of CO2 with epoxides. The complexes, when combined with tetrabutylammonium halides, were active...
Hollow and microporous metal free/Cr-porphyrin networks were prepared via the Sonogashira coupling of metal-free or Cr- tetra(4-ethynylphenyl) porphyrins and 1,4-diiodobenzene on the surface of silica templates followed by silica etching. Zinc was introduced to hollow and microporous metal free porphyrin network (H-MPN) through postsynthetic modifi...
Citations
... Research Article doi.org/10.1002/chem.202202105 that the ILs were grafted on the surface and channels without affecting mass transference. [35] ICP-OES was used to confirm the content of metal elements. The specific data is shown in Table 1. ...
Herein, the synthesis of a new type of catalyst, SBA−M (Schiff complex of different metal types grafted on SBA‐15) based on a quaternization reaction, is described. Various amounts of ionic liquid were grafted into the pore channels of SBA‐15 using the post‐grafting method, which allowed the ionic liquid to be grafted into the pore channels restrictively. Notably, over six cycles, SBA−Mn (0.2) has been shown to maintain its catalytic activity and stability. In addition, a reaction mechanism for the cycloaddition of CO2 with epoxides based on density‐functional theory is proposed. The cycloaddition reaction of CO2 and epoxides is an efficient way of carbon fixation. It is demonstrated that the metal coordinated with the oxygen atom of the epoxides and that a halogen attacked the carbon of epoxides. Moreover, theoretical calculations and synthesis strategy provide a new approach for CO2 conversion.
... The catalytic performance of the above-mentioned three immobilized catalysts for synthesizing PC with CO2 and PO was investigated and the results were shown in Table 1. [9][10]. The conversion rate and selectivity were 92.7% and 82.7%. ...
In this work, three composite polyether imidazole ionic liquids (PIILs) supported on molecular sieve (MCM-22) with terminal hydroxyl, carboxyl and amino groups were synthesized with the help of silane coupling agent 3-chloropropyltriethoxysilane (CPTES). They were used for cycloaddition of CO 2 and propylene oxide (PO) in a fixed-bed reactor. The results showed that MCM-22-CPTES-HOOC-[PECH-MIM]Cl/[ZnBr 2 ] was the best catalytic properties in this reaction. The conversion rate and selectivity were 92.7% and 82.7%.
... Ionic liquids (ILs), as environmentally friendly chemical materials, have been widely used in various fields including organic synthesis, biomass dissolution, catalysis, and composite materials preparation due to their unique properties [6][7][8][9][10]. In recent years, studies on the conversion of CO 2 to cyclic carbonate using ILs as catalysts have been widely reported [11][12][13], demonstrating that the catalytic performance of ILs as a single component in catalysts is unfavorable, and the addition of Lewis acids or other co-catalysts in the catalysts is necessary to achieve better catalytic activity. However, these studies are still associated with several disadvantages including limitation of the intermittent tank reaction system, catalyst separation, and product purification [14]. ...
Traditional ionic liquids (ILs) catalysts suffer from the difficulty of product purification and can only be used in homogeneous catalytic systems. In this work, by reacting ILs with co-catalyst (ZnBr2), we successfully converted three polyether imidazole ionic liquids (PIILs), i.e., HO-[Poly-epichlorohydrin-methimidazole]Cl (HO-[PECH-MIM]Cl), HOOC-[Poly-epichlorohydrin-methimidazole]Cl (HOOC-[PECH-MIM]Cl), and H2N-[Poly-epichlorohydrin-methimidazole]Cl (H2N-[PECH-MIM]Cl), to three composite PIIL materials, which were further immobilized on ZSM-5 zeolite by chemical bonding to result in three immobilized catalysts, namely ZSM-5-HO-[PECH-MIM]Cl/[ZnBr2], ZSM-5-HOOC-[PECH-MIM]Cl/[ZnBr2], and ZSM-5-H2N-[PECH-MIM]Cl/[ZnBr2]. Their structures, thermal stabilities, and morphologies were fully characterized by Fourier-transform infrared spectroscopy (FT-IR), X-ray diffractometry (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The amount of composite PIIL immobilized on ZSM-5 was determined by elemental analysis. Catalytic performance of the immobilized catalysts was evaluated through the catalytic synthesis of propylene carbonate (PC) from CO2 and propylene oxide (PO). Influences of reaction temperature, time, and pressure on catalytic performance were investigated through the orthogonal test, and the effect of catalyst circulation was also studied. Under an optimal reaction condition (130 °C, 2.5 MPa, 0.75 h), the composite catalyst, ZSM-5-HOOC- [PECH-MIM]Cl/[ZnBr2], exhibited the best catalytic activity with a conversion rate of 98.3% and selectivity of 97.4%. Significantly, the immobilized catalyst could still maintain high heterogeneous catalytic activity even after being reused for eight cycles.
... catalyst by SEM, the results were shown in Fig. 4. The apparent morphology of SBA-15 was porous structure. At the same magnification, the surface of SBA-15 had a little change before and after supporting ionic liquids, there was a layer of liquid for the apparent of SBA-15 [55][56][57]. It suggested that the part of TEA immobilized on the support pore, and some of them were transferred to the surface of the supporter. ...
... It suggested that the part of TEA immobilized on the support pore, and some of them were transferred to the surface of the supporter. However, the above phenomenon did not have influence on the phase transition [55]. ...
A series of triethanolamine-modified mesoporous SBA-15 catalysts were synthesized by a facile one-pot process, and used as the catalyst for the synthesis of cyclic carbonates through the cycloaddition of CO2 with epoxides. The properties of catalysts were characterized by nitrogen adsorption–desorption, elemental analysis (EA), Fourier transform infrared (FT-IR) spectra, Magic angle spinning nuclear magnetic resonance (MAS NMR), X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscopy (TEM), and the results suggested that triethanolamine (TEA) had been successfully immobilized on SBA-15. It was highly active in the cycloaddition reaction, in which the maximum yield of PC could achieve 93.47% under the conditions as follow: catalyst amount of 0.20 g, reaction temperature of 110 °C, reaction pressure of 2.0 MPa and reaction time of 4 h. Notably, the catalyst can be easily recovered by filtration, and it can be retained most of its catalytic stability and activity after five recycling times. On the basis of the experimental results, the interactions between the catalysts and the substrates were studied by DFT calculations, and the possible mechanism for the reaction was proposed.
... Given the liquid nature of ILs, a number of practical impediments can complicate their use in actual devices. [16][17][18] These issues have been addressed by IL immobilization by various techniques that include covalent attachment of IL cations or anions to solid supports, [18][19][20][21] formation of thin a) Author to whom correspondence should be addressed: bakergar@ missouri.edu liquid films adsorbed to resins, 22 confinement within porous structures, 23 or polymerization of reactive monomers to generate polymer analogs of ionic liquids (i.e., poly-ILs). ...
Bacterial cellulose ionogels (BCIGs) represent a new class of material comprising a significant content of entrapped ionic liquid (IL) within a porous network formed from crystalline cellulose microfibrils. BCIGs suggest unique opportunities in separations, optically active materials, solid electrolytes, and drug delivery due to the fact that they can contain as much as 99% of an IL phase by weight, coupled with an inherent flexibility, high optical transparency, and the ability to control ionogel cross-sectional shape and size. To allow for the tailoring of BCIGs for a multitude of applications, it is necessary to better understand the underlying principles of the mesoscopic confinement within these ionogels. Toward this, we present a study of the structural, relaxation, and diffusional properties of the ILs, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([emim][Tf2N]) and 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([bmpy][Tf2N]), using ¹H and ¹⁹F NMR T1 relaxation times, rotational correlation times, and diffusion ordered spectroscopy (DOSY) diffusion coefficients, accompanied by molecular dynamics (MD) simulations. We observed that the cation methyl groups in both ILs were primary points of interaction with the cellulose chains and, while the pore size in cellulose is rather large, [emim]⁺ diffusion was slowed by ∼2-fold, whereas [Tf2N]⁻ diffusion was unencumbered by incorporation in the ionogel. While MD simulations of [bmpy][Tf2N] confinement at the interface showed a diffusion coefficient decrease roughly 3-fold compared to the bulk liquid, DOSY measurements did not reveal any significant changes in diffusion. This suggests that the [bmpy][Tf2N] alkyl chains dominate diffusion through formation of apolar domains. This is in contrast to [emim][Tf2N] where delocalized charge appears to preclude apolar domain formation, allowing interfacial effects to be manifested at a longer range in [emim][Tf2N].
The chemical conversion of CO2 into cyclic carbonate is an effective method for the resource utilization of CO2 and the production of cyclic carbonates. Herein, a series of polymer‐supported quaternary phosphonium ionic liquid catalysts with high grafting amount have been systematically designed and synthesized, and all catalysts could promote efficient fixation of CO2 into cyclic carbonate. According to the results of the experiment and simulation, it was found that the high catalytic activity was ascribed to the weak interaction energy of the anion and cation of the catalyst. Among them, PS−TPP−Cl, with lower interaction energy of 72.2 KJ/mol, showed better performance. Yet even after being recycled five times, its conversion of propylene oxide with little loss was still above 95 %. Furthermore, a possible cycloaddition mechanism for the synergetic effect of cation‐anion coordination has been proposed. This work will shed new light on the development of novel heterogeneous catalysts with promising properties for industrial applications.
Carbon dioxide as the main culprit of global temperature rising has seized the attention worldwide. CO2 capture and storage can rapidly decrease the CO2 concentration in the atmosphere. As it is also recognized as eminent C1 source, reasonable CO2 utilization is a promising method for solving CO2 problems. Among various CO2 conversion pathways, epoxide-CO2 cycloaddition is a fascinating approach owing to its 100% atomic efficiency. Till nowadays, various sorbents and catalysts emerged for efficient CO2 capture and epoxide-CO2 cycloaddition catalysis. Mesoporous SiO2 as a good carrier attracts tremendous interests in its improvements for more effective CO2 capture and conversion catalysis in the past two decades resulting from its good hydrothermal stability and easy-modification. Abundant silanol as hydrogen bond donors also benefits the reaction catalysis. Functionalization from metal introduction to nonmetal active components supporting has been applied to improve the CO2 adsorption capacity and the catalytic activity of mesoporous SiO2 to epoxide-CO2 cycloaddition. Therefore, an overview on the progress in functionalized mesoporous SiO2 for CO2 capture and conversion to cyclic carbonates catalysis is summarized here to make a clear understanding to the role of functionalized mesoporous SiO2 as CO2 sorbents and catalysts in the epoxide-CO2 cycloaddition reaction.
The conversion of atmospheric carbon dioxide (CO2) gas mixtures and epoxides to cyclic carbonates is an environmentally beneficial execution strategy, which is a useful platform chemical. However, this reaction is overly dependent on harsh reaction conditions including temperature and/or CO2 pressure in the traditional conversion process. We report a series of facilely prepared functionalized ionic liquids (ILs) for the one-pot synthesis of styrene carbonate (SC) from pure/diluted CO2 with styrene oxide (SO). Which achieved a yield up to 99% under atmospheric CO2 conditions. In addition, with the assistance of a small amount of catalyst, the product yield remained at 99% under diluted CO2 conditions. This result demonstrates that functionalized ILs could effectively catalyze the cycloaddition reaction of low-pressure CO2 without any co-catalysts such as metals, organic solvents, and active additives. The density functional theory (DFT) calculations combined with experimental results revealed that the highest catalytic ability of Cat.2 was ascribed to the synergic catalysis between positive charge delocalized cations and Br⁻ anions to efficiently activate the substrates. Furthermore, the best ILs catalyst can be reused five times without significant reduction in catalytic activity, which shows its great potential for chemical conversion of atmospheric CO2.
Graphical Abstract
The cycloaddition reaction of CO2 with epoxides is challenging, thereby requiring the development of environmentally friendly catalysts. Herein, a strategy was developed to construct a multifunctional heterogeneous magnetic catalyst (MPNPs-[ImR2NH2][ZnBr3]) of aminoethyl imidazole metal halide ionic liquids coated on nano-sized CoFe2O4@polystyrene for CO2 cycloaddition. The created catalytic system displayed the intramolecular synergy of ternary active sites (Zn²⁺, Br⁻, and –NH2), as well as coupling of catalysis and magnetic separation. In the absence of co-catalyst and solvent, MPNPs-[ImR2NH2][ZnBr3] exhibited excellent catalytic performance for CO2 cycloaddition (99.92% yield and 100% selectivity) at 120 ℃ with 0.16 mol% catalyst dosage in 2.5 h. By appropriately increasing the reaction duration and catalyst dosage, 98.83% conversion and 99.26% selectivity were achieved even at mild conditions of 60 °C and 0.1 MPa. After 10 cycles of reuse, the recycled MPNPs-[ImR2NH2][ZnBr3] demonstrated the same high-efficiency activity as the fresh catalyst, as well as excellent stability and magnetic separation. Based on the density functional theory (DFT) calculations, the intramolecular synergy of ternary active sites and the catalytic mechanism of bimolecular activation based on the multifunctional structure were proposed. This excellent catalyst was attributed to the intramolecular synergy of ternary active sites, large loading of active centers, lower internal diffusion resistance, the inert protective effect of polystyrene layer and the easily magnetic separation of CoFe2O4, highlighting a new direction for green catalytic chemistry.
