Catalyst For Cycloaddition Of CO2 Research Articles

Graphene oxide grafted hydroxyl-functionalized ionic liquid: A highly efficient catalyst for cycloaddition of CO2 with epoxides

A grafted 1-(2-hydroxyl-ethyl)-imidazolium-based ionic liquid (GO-HEIMBr) was developed via immobilizing 2-bromoethanol onto an imidazole-modified graphene oxide, which was prepared in a one-pot process. The physicochemical properties of GO-HEIMBr were characterized by atomic force microscopy, X-ray photoelectron spectroscopy, thermogravimetry analysis, Fourier transform infrared spectroscopy, and elemental analysis. In the solvent-free cycloaddition reactions of CO2 with epoxides to cyclic carbonates, GO-HEIMBr exhibited excellent catalytic activities. A maximum yield of the target cyclic carbonate arrived at 99% using 0.35mol% catalysts at 140°C in 4h. In addition, the catalyst could be easily recovered and reused for seven times without significant loss of activity. A possible catalytic mechanism was proposed for the cycloaddition over GO-HEIMBr.

Amino-Functional Imidazolium Ionic Liquids for CO2 Activation and Conversion to Form Cyclic Carbonate

A series of amino-functional imidazolium ionic liquids have been prepared and used as catalysts for cycloaddition of CO2 with epoxide. The reactions generated the cyclic carbonate even at room temperature under atmospheric pressure. Under the optimal reaction conditions, the propylene carbonate was yield to 98.0 % in the presence of [APbim]I, and the ionic liquids could be reused at least nine times without noticeable decrease in activity and selectivity. Besides, the reaction mechanism was proposed. Cycloaddition of CO2 with epoxides catalyzed by amino-functionalized imidazolium ionic liquid can achieve CO2 activation and conversion directly. The reactions generated the corresponding products even at room temperature under atmospheric pressure. Amino-functionalized imidazolium ionic liquid has showed excellent catalytic activity, reusability and general applicability.

C60 fullerenol as an active and stable catalyst for the synthesis of cyclic carbonates from CO2 and epoxides.

C60 fullerenol was found to be a highly active, selective and stable catalyst for cycloaddition between CO2 and epoxides to produce various cyclic carbonates with excellent yields (89-99%). A solid/liquid interfacial hydrogen-bond assisted mechanism was proposed to account for its high efficiency.

Low-Cost Polymer-Supported Quaternary Ammonium Salts as High-Efficiency Catalysts for Cycloaddition of CO2 to Epoxides

Polystyrene grafted with quaternary ammonium salts were obtained by direct quaternarization of chloromethylated polystyrene with N,N-dimethylethylamine, N,N-dimethylglycine (denoted as PS-QNS and PS-CQNS, respectively). These two polymer-supported ionic liquids were found to show high catalytic efficiency towards the cycloaddition of CO2 to epoxides. The effects of catalyst amount, reaction temperature, initial CO2 pressure, and reaction time on the yield of cyclic carbonates were investigated systematically. Under the optimal reaction conditions (150 °C, initial CO2 pressure 2.0 MPa and 5 h), propylene carbonate yield and selectivity in the cycloaddition of CO2 to propylene oxide over PS-CQNS were 96.2 and 99.3 % whereas those over PS-QNS were 97.9 and 99.5 %, respectively. It was observed that the reusability of PS-QNS was excellent. From the viewpoint of industrial application, PS-QNS is attractive in terms of catalytic efficiency, cost and simplicity in preparation. Polystyrene bearing quaternary ammonium salt ionic liquids (denoted as PS-QNS and PS-CQNS) were fabricated and evaluated for solventless synthesis of cyclic carbonates from CO2 and epoxides. The catalysts are low in cost and simple to prepare, and show good activity, selectivity, stability and reusability towards the cycloaddition reaction.

Chitosan functionalized ionic liquid as a recyclable biopolymer-supported catalyst for cycloaddition of CO2

Development of efficient, cheap and recyclable catalysts for a reaction under green reaction conditions is still a very attractive topic. In this work, the cycloaddition reactions of CO2 with various epoxides to form five-membered cyclic carbonates catalyzed by chitosan functionalized 1-ethyl-3-methyl imidazolium halides (CS-EMImX, X = Cl, Br) without additional solvent and metal co-catalyst were achieved in high yield and selectivity. The catalyst could be easily recovered and reused five times with high catalytic activity and selectivity. Besides, a possible catalytic cycle for the hydrogen bond assisted ring-opening of epoxide and activation of CO2 induced by the nucleophilic tertiary nitrogen of the chitosan was also proposed. The process represents a simple, ecologically safe and cost-effective route to synthesize cyclic carbonates with high product yield, as well as easy catalyst recycling.

Carboxylic acid functionalized imidazolium-based ionic liquids: efficient catalysts for cycloaddition of CO2 and epoxides

In this study, a series of imidazolium-based ionic liquids (ILs) having carboxylic acid moieties were synthesized and used as new homogeneous catalysts to synthesize cyclic carbonates from CO2 and epoxides. Even in the absence of any co-catalyst and organic solvent, carboxylic-acid-functionalized ILs showed better catalytic activity in the coupling reaction of CO2 and styrene oxide for the production of styrene carbonate than did hydroxyl-functionalized ILs and conventional ILs without any functional moieties. A detailed investigation was carried out on a variety of factors that affected the reactivity, such as the alkyl chain length and the molecular composition of IL molecules including the halide ions. The effect of various reaction parameters such as reaction time, temperature, CO2 pressure and catalyst amount was also investigated in detail. The mechanism underlying the enhanced rate of the cycloaddition reaction in the presence of carboxylic-acid-functionalized ILs was proposed.

A facile one-step synthesis to cross-linked polymeric nanoparticles as highly active and selective catalysts for cycloaddition of CO2 to epoxides

A very convenient one-step synthesis to cross-linked polymeric nanoparticles by conventional radical copolymerization without the addition of stabilizers or surfactants was explored. Moreover, these nanoparticles exhibited excellent stability, activity and selectivity in the cycloaddition reaction of CO(2) to epoxides and could be separated from the products easily and reused.

Synthesis of cyclic carbonates from epoxides and CO2 catalyzed by potassium halide in the presence of β-cyclodextrin

Development of efficient, cheap and non-toxic catalysts for cycloaddition of CO2 with epoxides to produce five-membered cyclic carbonates under greener reaction conditions is still a very attractive topic. In this work, cycloaddition of CO2 with propylene oxide (PO) to propylene carbonate (PC) catalyzed by potassium halide (KCl, KBr, and KI) in the presence of β-cyclodextrin was studied at various conditions. It was discovered that potassium halide and β-cyclodextrin (β-CD) showed excellent synergetic effect in promoting the reactions, and KI-β-CD catalytic system was the most efficient among them. The optimal temperature for the reaction was around 120 °C, and the reaction rate reached maximum at about 6 MPa at this temperature. The reaction could be completed in 4 h with very high selectivity. The decrease of the yield of PC was not noticeable after KI-β-CD was reused five times, indicating that the catalyst was very stable. KI-β-CD catalytic system was also very active and selective for cycloaddition of CO2 with other epoxides, such as glycidyl phenyl ether, epichlorohydrin, and styrene oxide. The mechanism for the synergetic effect is discussed.