Combining Experimental And Theoretical Study On The Investigation And Transformation Of CO₂

Converting CO₂ into raw chemical materials,which have high added value,is a crucial procedure to effectively attenuate the content of CO₂ in atmosphere.Green chemistry is always the hot topic to scientists,comparing with most inorganic catalysts in CO₂ catalytic reaction,organic catalysts play an essential role in green friendly-environment.N-Heterocyclic Olefins?NHOs?,as environment-friendly organic catalysts,could catalyze the formation of epoxy carbonates by reacting CO₂ gas with alkyne alcohols in excellent yields under very mild condition.Moreover,Covalent Organic Frameworks?COFs?have been widely utilized in the cycloaddition of CO₂ to epoxides to produce cyclic carbonates because of its excellent chemstability,well-defined porous structure and abundant catalytic active center.In view of its particular optical property,small organic molecular squaraines have also been extensively reported in the field of CO₂ gas capture and detection.In this paper,firstly,by theoretically simulating the reaction of CO₂ gas and alkyne alcohols in the preparation of epoxy carbonates catalyzed NHOs,the overall pathway and potential mechanisms has been detailedly investigated.Moreover,the metalloporphyrin has been firstly incorporated into COFs materials as the basic unit,and applied those metalloporphyrin-based COFs to catalyze the cycloaddition reaction of epoxide with CO₂ gas.Finally,the squaraine SQ has been applied in the optical qualitative and quantitive detection of CO₂ gas in the absence of any alkaline medium.The following conclusions are drawn from the research:?1?Through the theoretical simulation of the potential path ways?A and B?in the reaction of alkyne alcohols and CO₂ gas to produce epoxy carbonates catalyzed by NHOs,results showed the path B holds an lower energy barrier values?12.25 Kcal/mol?and subjected to three steps,which indicated that path B is the optimal path and fit in with experimental data.?2?The porphyrin-based COF material?COF-366?was prepared and different metal ions M?M = Zn,Co?were loaded on the center of the porphyrin ring of COF material?COF-366-Zn and COF-366-Co?.Subsequently,the catalytic performance of these two COFs was investigated in the conversion of CO₂ gas into the epoxy carbonates.Results showed that the COF-366-Zn exhibited the excellent catalytic activity with the yield up to 95% and selectivity of 99%,and the catalyst performance remained invariablenes after five times repeated.?3?The squaraine SQ was prepared and its optical response to the CO₂ gas was studied in alcohols without any alkaline medium.Results showed SQ can be applied to “naked-eye” detection of CO₂ gas in methanol,the color of solution turned form colorless to cyan.Moreover,this detection carried out to be qualitative and quantitive and hold the limit of detection down to 26 ppm.