Study On The Preparation Of Propylene Carbonate And N-formylpyrrolidine By CO₂ Fixed Conversion

In view of the growing global greenhouse effect,carbon dioxide?CO₂?has been paid close attention to by chemical methods.At the same time,it is urgent to develop a practical and environmentally friendly carbon resource to replace non renewable fossil fuels.As a abundant,low-cost and nontoxic C1 resource,the transformation of carbon dioxide?CO₂?into value-added compounds has attracted wide attentions in the both fields of green and synthetic chemistry.Moreover,the utilization of CO₂ as carbon source for fine chemical synthesis is one of primary methods to reduce the am ount of CO₂ in the atmosphere.Therefore,this paper starts with the fixed carbon dioxide,which can be converted into useful chemicals.The main results are shown as follows:1)Bimetallic Pd-Au catalyst was prepared by depositing the Pd-Au alloy nanoparticles on polyaniline-functionalized carbon nanotubes?PANI-CNT?and the resulting Pd-Au/PANI-CNT catalyst exhibited excellent catalytic activity for the N-formylation of pyrrolidine using CO₂/H2..Under the optimum conditions,the yield of98.3% N-pyrrolidine was obtained by Pd-Au/PANI-CNT and CO₂/H2 at with a molar ratio of Pd/Au to 1:1.Our research further reveals that Pd atoms should be the true active sites for the hydrogenation reaction and the N-formylation reaction might occur mainly over Pd atoms or over the interface between Pd atoms and Au atoms for the bimetallic Pd-Au/PANI-CNT catalyst.The enhanced catalytic performance of bimetallic Pd-Au/PANI-CNT is mainly related to beneficial interactions between Pd atoms and Au atoms,leading to the changes of the electronic properties of the formed bimetallic Pd-Au nanoparticles.The catalyzed range and limitations of the catalyst were explored on the basis of the model reaction.The limitations of the catalyst and the catalytic range are explored by the addition of different types of substrates such as linear amines,aromatic amines,primary amines,secondary amines and the like.2)A new core-double-shell microsphere [Fe3O4@SiO₂@Zn?Por?OP] was designed and prepared by coating a core-shell composite of Fe3O4 magnetic core and SiO₂ shell?Fe3O4@SiO₂?with a zinc porphyrin-based organic polymer [Zn?Por?OP].Besides,removing the inner core-shell particles of Fe3O4@Si O₂ from Fe3O4@SiO₂@Zn?Por?OP led to the formation of the Zn?Por?OP hollow microspheres which exhibited efficient catalytic performance for cycloaddition of carbon dioxide and propylene oxide to give propylene carbonate?PC?.For Fe3O4@SiO₂@Zn?Por?OP composite,the outer organic shellZn?Por?OP serves as the catalytically active layer for the cycloaddition and a PC yield of97% was obtained.More importantly,the catalyst could be easily recycled from the reaction mixture by magnetic separation and no significant loss of activity was observed after sixteen cycles.Therefore,this composite microsphere can provide insightful information for further design of magnetic materials with controllable morphology regulation as well as can be extended toward the development of highly efficient,stable and recyclable catalysts in other catalytic reaction system.