Salen-Cu(Ⅱ)@MIL-101(Cr)as an efficient heterogeneous catalyst for cycloaddition of CO2 to epoxides under mild conditions

A double active center system, namely Salen-Cu（Ⅱ）@MIL-101（Cr）, was successfully synthesized via the"ship in a bottle" approach, which acted as a bifunctional material for both capture and conversion of COin a single process. For the first time, Salen-Cu（Ⅱ）@MIL-101（Cr） catalyst was developed for the synthesis of propylene carbonate from COand propylene oxide under room temperature and ambient pressure with a yield of 87.8% over 60 h. Furthermore, the reaction mechanism was also discussed.

Mesoporous poly(ionic liquid)s with dual active sites for highly efficient CO_(2)conversion

Atmospheric CO_(2)concentrations are soaring due to the continued use of fossil fuels in energy production,an anthropogenic activity that is playing a leading role in global warming.Thus,research aimed at the capture and conversion of CO_(2)into value-added products,such as cyclic carbonates,is booming.While CO_(2)is an abundant,cheap,non-toxic,and readily accessible Cl feedstock,its thermodynamic stability necessitates the development of highly efficient catalysts that are able to promote chemical reactions under mild conditions.In this work,a novel mesoporous poly(ionic liquid)with dual active sites was synthesized through a facile method that involves co-polymerization,post-synthetic metalation,and supercritical CO_(2)drying.Due to a high density of nucleophilic and electrophilic sites,the as-prepared poly(ionic liquid),denoted as P2D-4BrBQA-Zn,offers excellent performance in a CO_(2)cycloaddition reaction using epichlorohydrin as the substrate(98.9%conversion and 96.9%selectivity).Moreover the reaction is carried out under mild,solvent-free,and additive-free conditions.Notably,P2D-4BrBQA-Zn also efficiently promotes the conversion of various other epoxide substrates into cyclic carbonates.Overall,the catalyst is found to have excellent substrate compatibility,stability,and recyclability.

Green and efficient cycloaddition of CO2 toward epoxides over thiamine derivatives/GO aerogels under mild and solvent-free conditions

Thiamine derivatives that are cheap, readily available, non-toxic and green are used as heterogeneous catalyst for the generation of cyclic carbonates through cycloaddition of CO_2 to epoxides without the need of co-catalyst and solvent. The interaction between thiamine hydrochloride(VB_1-Cl) and substrates(CO_2 and propylene oxide) was proven by ultraviolet-visible spectroscopy and ~1H nuclear magnetic resonance analysis, and it is deduced that the synergistic action among multi-functional groups(hydroxyl, halide anion and amine) is a favorable factor for cycloaddition reaction. A series of VB_1/GO aerogels were facilely prepared through the addition of aqueous VB_1 derivatives to a suspension of GO in ethanol at room temperature. It was found that the aerogel generated through the interaction of VB_1-Cl with GO shows catalytic activity and stability higher than those of VB_1-Cl. It is because the electrostatic interaction between GO and VB_1-Cl enhances the nucleophilicity and leaving ability of anion. The effects of reaction temperature, catalyst loading, CO_2 pressure and reaction time on CO_2 cycloaddition to propylene oxide were thoroughly studied.