Study On The Direct Synthesis Of Cyclic Carbonates From Olefins And CO₂

Carbon dioxide(CO2)is arguably one of the most well-known greenhouse gases,but also an abundant,renewable,and low toxicity C1 feedstock.The catalytic conversion of CO2 into valuable chemicals is a one of the most fascinating way for carbon capture and utilization(CCU).And the chemical fixation of CO2 into cyclic carbonates is one of the most promising CO2 utilization routes in industry.Currently,cyclic carbonates are generally synthesized by the cycloaddition of CO2 into epoxides.However,this reaction usually involves the use of expensive and toxic epoxides,and often faced with storage problems.Moreover,the high requirement of equipment,huge energy consumption and low economic benefits severely restrict the industrial scale and market competitiveness of cyclic carbonates.Olefins,a kind of cheap and low-toxicity bulk chemicals,are the raw materials for preparing epoxides in industry.Therefore,the direct synthesis of cyclic carbonates from olefins instead of epoxides would be appealing because of the improved economic efficiency and environmental friendliness.It is also of great significance for the traditional process innovation.However,most of the reported catalytic systems faced with problems of poor selectivity and harsh reaction conditions.In this thesis,based on biomimetic catalysis and micro-nano catalysis,new efficient catalytic systems have been developed to realize the one-step preparation of cyclic carbonate from olefin and CO2 under mild reaction conditions.The main contents of this paper are as follows:1.Four metalloporphyrin complexes,such as MnTPP,Mn(TDCPP)Cl,T(p-Cl)PPMn and T(p-Cl)PPZn,were synthesized and characterized by NMR,MALDI-TOF and so on.And a biomimetic metalloporphyrin catalyzed olefin-O2/H2O2-CO2 system was developed for the synthesis of cyclic carbonates.Utilizing a two-step temperature controlled strategy,Mn(TDCPP)Cl effectively catalyzes the transformation of styrene to cyclic carbonate with 59%yield.2.Four porous metal-organic frameworks M-gallates(M=Ni,Mn,Co,Mg)were synthesized by the treatment of different metal salts with inexpensive gallic acid and used as catalysts for the cycloaddition of CO2 to epoxides via a tandem olefin epoxidation-cycloaddition reaction.The Co-gallate is superior to other isostructural M-gallates and can effectively catalyze the cycloaddition reaction of CO2 with various epoxides(isolated yields up to 90%)under ambient pressure and solvent free reaction conditions.Furthermore,Co-gallate could be recycled five times without loss of catalytic activity.To investigate the influence of external surface area on the reaction,Co-gallate-T with different crystal sizes were prepared at different temperatures.In addition,M-gallates were also successfully applied to the direct preparation of cyclic carbonates from olefins,among which Ni-gallate showed the best catalytic performance for this reaction with 99%conversion of styrene and 84%selectivity for styrene carbonates.3.Inspired by the tunability of metal-organic frameworks(MOFs),we introduced amino groups to the organic linkers of Co(Hoba)2.The obtained amino modified MOF material Co(Hoba)2-NH2 shows significantly higher catalytic activity for the direct conversion of olefin to cyclic carbonate as compared with that of Co(Hoba)2.In addition,based on the experimental results and previously reported works in literature,the mechanism of Co(Hoba)2-NH2 catalyzed reaction of olefin with CO2 to form cyclic carbonates was discussed.