Preparation And Characterization Of Perovskite-type Complex Oxides And Inquiry Of Its Activity

Perovskite complex oxides ABOy is widely used because of its special crystal structure and excellent physical, chemical performance. And more and more researchers pay attention to it. Perovskite complex oxides ABOy was prepared and explored in this paper, which lay foundation for future industrial application.The solid phase sintering, citric acid and microemulsion method were adopted to synthesize perovskite composite oxides Then, the influence of different reaction conditions on product forming process was examined, and the optimum reaction conditions were determined Finally, the activity of BaFeO2.64 as catalyst in the catalytic hydrogenation of tert-butylbenzene and dehydrogenation reaction of methylcyclohexane was explored. The results were as follows: The appropriate calcination temperature and time of solid phase method synthesizing Ba FeO2.64 were 977℃ and 12 h, respectively. The perovskite composite oxides BaFeO2.64 had been confirmed to be 6H-type hexagonal structures.It belonged to P63/mmc group,and the size of the cell was 17.1nm. The aperture was so large that large molecules was easy to enter. Unfortunately, the overall uniformity of the powder was poor. The suitable reaction temperature and time of citric synthesizing Ba FeO2.64 was 70℃and 2h.The suitable calcination temperature time was 900℃and 8h. Compared with the solid sintering method, the perovskite composite oxides powder prepared by citric was more uniform without reunion phenomenon. On the basis of microemulsion preparing for M type barium ferrite, perovskite composite oxides were synthesized by microemulsion method. The results showed that: The suitable water bathing temperature was 60℃.The appropriate surfactant concentration S was 0.20mol/L. The suitable calcination temperature is 750℃.The appropriate calcination time is 3h.The influence of hydrogen reduction on perovskite composite oxides BaFeO2.64 was also examined under high temperature and pressure. The results showed that the number of oxygen reduced gradually, and even some BaFeO2 appeared. This result lay theoretical foundation for the research of nature BaFeO2 in the future. In addition, BaFeO3 has been applied in industrial catalysis, the catalytic activity of BaFeO2.64 was explored in this article. Results of BaFeO2.64 as catalysts used in the catalytic hydrogenation showed that when the reaction temperature was 351℃, the reaction time of 2h, hydrogen pressure of 11 MPa, the conversion rate for tertiary butyl benzene was highest(1.40%), in general, the catalyst activity in hydrogenation reaction was low. The results of BaFeO2.64 as catalysts used in the catalytic dehydrogenation reaction showed that when the rate of catalyst was 1:4, the reaction temperature was 420℃, the highest conversion rate of methyl cyclohexane was 4.62%, but the catalyst activity was still low on industrial applications. However, mass spectrometry analysis results demonstrated that the perovskite composite oxides catalysts had the ability of inducing methyl cyclohexane selectively dehydrogenate into methyl cyclohexene, this finding adds new path for the synthesis of methyl cyclohexene and paves good foundation for the improvement of catalyst in performance and types in the process of the synthesis of methyl cyclohexene.