Study On The Synthesis Of Propylene Carbonate From Carbon Dioxide Catalyzed By Magnesium Oxide And Alumina Oxide

Carbon dioxide?CO₂?and its increasing concentration in the global has been becoming a hot issue with the acceleration of industrialization.It has repoted that the emission of CO₂ has caused an increasingly?green house?.But,the synthesis of propylene carbonate?PC?from CO₂ and propylene epoxide?PO?is one of the most successful chemical fixations of CO₂ for its abundant,cheap and renewable carbon source.The fixation of CO₂ to synthesis PC is a very attractive route,which not only satisfy growing human demand for chemical raws,but also act as a significant role to positively affect the environment issue.In order to overcome the disadvantages for the numerous catalysts,such as unsatisfactory,expensive cost,difficulties in products separation and reused etc.Based on the abundant of magnesium chloride and aluminum resource,urea reacted as the precipitant for it could prepare multi-pores catalyst.we prepared high activity MgO and?-Al₂O₃ through direct precipitation method and the samples are characterized by XRD,FT-IR and SEM etc.In this paper,the high activity MgO were prepared by MgCl₂ and CO?NH₂?₂ and different morphologes of MgO catalyst under different calcination temperature were used for the heterogeneous catalytic to synthesise PC from CO₂ and PO,the results indicted that the polyhedron MgO catalyst under 800?calcination temperature gave better catalytic performance.The amount of MgO,reaction time,reaction temperature and initial CO₂pressure etc factors were investigated in the cycloaddition reaction.When used 0.20 g MgO to fulfill CO₂ cycloaddition reaction,the PC yield was 95%and selectivity was above 98%under 140?,1.50 MPa initial CO₂ for 10 h.In addition,we also studied the catalytic performance different morphologies MgO through several precipitants and commercial MgO,the results indicated that the prepared MgO by urea precipitant had higher catalytic activity.In addition,the polyhedron MgO still retained better yield?88%?after four cycles.We also successfully prepared soild spherical?-Al₂O₃ through aluminum sulfate and urea,the different solvents,amount of catalyst,reaction time,reaction temperature and nitial CO₂pressure etc factors were investigated in the CO₂ coupling reaction.The optimum reaction conditions of 1 mL methyl formamide as the solvent,10 mL PO,140?,1.50 MPa initial CO₂,10 h reaction time and the catalyst amount of 0.20 g?-Al₂O₃,the yield of PC could reach 93%and the selectivity of PC was above 99%.Besides,different types of metal oxide were used to carried the CO₂ cycloaddition,we found that?-Al₂O₃ had better results in our work,the PC yield was above 80%after four times.The prepared high active MgO and?-Al₂O₃ catalyst by cheap magnesium chloride,aluminum sulfate and urea have a huge potential.