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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.

We report for the first time the hydrothermal synthesis of MgO–SnO2 solid superbase using P123 as template. The basicity of the materials was determined by two approaches of Hammett indicators method and temperature-programmed desorption using CO2 as adsorbate (CO2-TPD). It was found that Mg/Sn molar ratio has an effect on MgO–SnO2 basicity, and superbasicity was observed only at Mg/Sn molar ratio of 1. With variation of Mg/Sn molar ratio, superbase strength (H -) was in the 26.5–33.0 range, showing superbasic value up to 0.939 mmol/g. The structure and texture of the as-prepared materials were studied by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and N2 physio-adsorption methods. We detected particles of spherical morphology having diameter of ca. 150 nm. N2 adsorption–desorption results suggested that the materials are of mesoporous structure, having specific surface area of 115.2 m2/g and average pore diameter of 6 nm. The superbase was found to exhibit excellent catalytic activity towards the one-pot synthesis of polyfunctionalized 4H-pyrans through the condensation of aldehydes, malononitrile, and an active methylene compound. Its excellent catalytic efficiency is related to its superbasicity of the MgO–SnO2. The results provide a new route for the design and preparation of composite oxide superbases. Furthermore, the solid superbases will facilitate a strategy for high-efficiency synthesis of polyfunctionalized 4H-pyrans. Novel MgO–SnO2 solid superbase was prepared using P123 as template. Its superbase strength was in the 26.5–33.0 range, showing superbasic sites up to 0.939 mmol/g. The material is of mesoporous structure,(having specific surface area of 115.2 m2/g and average pore diameter of 6 nm. It was found to exhibit excellent catalytic activity towards the one-pot solvent-free synthesis of polyfunctionalized 4H-pyrans through the condensation of aldehydes, malononitrile, and an active methylene compound. The results provide a new route for the design and preparation of composite oxide superbases.

3-(2-hydroxyl-ethyl)-1-propylimidazolium bromide (HEPIMBr) was immobilized onto SBA-15, Al-SBA-15 mesoporous molecular sieves and SiO2 by chemical grafting method. The materials were characterized and used as catalysts for solvent-free synthesis of cyclic carbonates from CO2 and epoxides under relatively mild conditions. Among them, the HEPIMBr immobilized on SBA-15 performs the best, showing carbonate selectivity and yield of ca. 100% (120 °C, 2.0 MPa, 2 h). The catalyst is thermally stable and shows good reusability. Based on the experimental results, a plausible reaction mechanism has been proposed for the catalytic reaction. 3-(2-hydroxyl-ethyl)-1-propylimidazolium bromide (HEPIMBr) was immobilized on SBA-15 mesoporous molecular sieve by chemical grafting method. It was found the material shows high catalytic efficiency and good stability towards the cyclic carbonates synthesis via. Cycloaddition of CO2 to epoxides. Moreover, the catalyst can be easily separated from the product. A plausible reaction mechanism has been proposed for the catalytic action.

A series of Zn-Al composite oxides that were modified with alkaline earth metals, Zn-M-Al-O (M = Mg, Ca, Sr, and Ba) were fabricated via calcination of the corresponding hydrotalcite precursors, and evaluated as catalysts for the synthesis of propylene carbonate (PC) from CO2 and propylene oxide. Among the Zn-M-Al-O catalysts, Zn-Mg-Al-O (Zn/Mg = 4.0, pH = 10, without hydrothermal treatment) is the best in performance, showing PC selectivity of 99.2% and yield of 88.8% (140 °C, 12 h). Furthermore, the Zn-Mg-Al-O catalyst can be readily reused and recycled without any loss of activity in a test of five cycles. Through detailed studies of the basic nature of the Zn-M-Al-O catalysts, it was found that a moderate basicity (6.1 ≤ H 0