Prearation Of PBA Material And Its Catalystic Performance For Cycloaddition Of Propylene Oxide

The cyclic carbonates formed by the reaction of carbon dioxide and epoxides have attracted the attention of the scientific community because of their 100%atomic economy.Five-membered cyclic carbonates are attractive in industry because of their wide range of uses.In electrochemistry,as an electrolytic element for lithium-ion batteries.In agriculture,as an aprotic solvent for cosmetics synthesis of acyclic carbonate intermediate.Used as a precursor in the synthesis of polymers in fine chemicals,pharmaceuticals and resins.Therefore,a variety of related high performance catalysts have been reported,including organometallic compounds,metal oxides,silicon-based main-chain imidazole salts,metal complexes,zeolites,tetrarylphosphonates,polymer-supported catalysts,ion exchange resins,N-heterocyclic carbenes,and ionic liquids（ILs）.However,most of them require high temperature and high pressure reaction conditions and have inherent limitations such as difficulties in separation and recovery.Therefore,it has become the research direction to prepare a new reusable heterogeneous catalyst for the cycloaddition reaction of carbon dioxide and propylene oxide.The bimetallic cyanide PBA is a candidate for cycloaddition reaction of propylene oxide due to its advantages of good stability,microporous structure and high specific surface area.Due to its structural defects,bimetal cyanide can be functionalized to enhance its catalytic performance.In this paper,a series of PBA catalysts were prepared by coprecipitation method,and ZnCoPBA was modified by organic solvent.The surface morphology,morphology and stability of the prepared bimetal cyanide materials were analyzed by XRD,FT-IR,XPS,SEM and TG.In addition,the catalytic performance and stability of the prepared Zncopba-TBA material for carbon dioxide cycloaddition reaction were investigated,and the difference of catalytic performance was analyzed.Combined with the characterization and experimental results,the following conclusions are drawn:（1）A series of Prussian blue analogues were prepared,which maintained the same octahedral shape and structure characteristics,with many internal channels,large specific surface area and Lewis acid sites,which made Prussian blue analogues a good candidate for catalyst.（2）When Prussian blue analogues were used to catalyze the cycloaddition reaction of propylene oxide and carbon dioxide,the catalytic activity of different bimetals for the reaction was different.Among the prepared Prussian blue analogues,ZnCoPBA shows the best catalytic activity,with a conversion rate of 90.8%for propylene oxide and a selectivity of>95%for propylene carbonate,indicating that there are differences in synergistic effects between different bimetals.（3）In this study,bimetal cyanide Zn₃[Co（CN）₆]₂was successfully modified by different organic ligands（methanol,ethanol,tert-butanol,DMF）,and the modified catalytic materials all have good crystallinity.The introduction of different organic ligands changed the crystallinity and morphology of ZnCoPBAs catalyst.The morphology of ZnCoPBA-MT,ZnCoPBA-ET and ZnCoPBA-TBA was spherical,while that of ZnCoPBA-DMF was cubic.（4）The prepared ZnCoPBA-MT,ZnCoPBA-ET,ZnCoPBA-TBA and ZnCoPBA-DMF catalytic materials were applied to the cycloaddition reaction of propylene oxide and carbon dioxide.The catalytic test results show that Zn COPBA-TBA has the highest catalytic activity,can make the propylene oxide conversion of more than 95%,at the same time,1,2-propylene glycol carbonate selectivity of 99%,and in the stability of the catalyst test results obtained that the catalyst has good repeatable practicality,good stability of the catalyst.