Preparation Of Perovskite-type Doped LaCoO₃ And Research On Catalytic Thermal Decomposition Of Them On HMX

Recently, intensive attention have been devoted to the perovskite-type compound oxide, because of its important catalytic value and development application.Firstly the method of citric acid sol-gel azeotropic distillation had been used to prepare superfine LaCoO₃. The powder had been characterized by transmission electric mirror (TEM),IR spectra et.al. Also, the mechanism of dryness of the wet congeal had been carried out in the thesis. The result of the experiment demonstrates that the water in the wet congeal glue was substituted by solvent benzene through the physical absorption, which prevent the dryness of the wet congeal glue and the reunion of the powder of the following calcining. In this way, the products prepared are distributed evenly, and the average size of the powder of LaCoO₃ is 50nm.Secondly perovskite LaCoO₃ was prepared by stearic Gel-Combustion process and Sol-Gel process. It can be found that LaCoO₃ prepared by stearic Gel-Combustion process was better. and LaCoO₃ were characterized by TEM, XRD, FTIR, B.E.T and TG-DTA. The results showed that the nano-scaled product LaCoO₃ was prepared. On this base, a series of doped LaCoO₃ ,as La_0.8Sr_0.2CoO₃, La_0.8Bi_0.2CoO₃,LaCo_0.8Bi_0.2O₃, LaCo_0.8Fe_0.2O₃ were prepared by the same way, they were characterized by XRD, results showed that all of them have the structure of ABO₃. The formation mechanism of stearic Gel-Combustion synthesis has been investigated by the time-temperature graph and TG-DSC of gel and stearic.The obtained perovskite nanosized oxide LaCoO₃ by combustion method and series A-site or B-site doped oxide were mingled into HMX (at the rate of 2:98(HMX) in quality), which is an important component of the propellant, the thermal decomposition effect of the nano products on HMX has been measured by TG. It has been found that the doped oxides of LaCoO₃ have vary extent catalytic activity to HMX, and they can made its thermal decomposition temperature bring forward. Among those, B-site doped iron LaCo_0.8Fe_0.2O₃and bismuth doped oxides have better catalytic effect on thermal decomposition of HMX.