AgO修饰硅藻土基多孔陶瓷复合材料的制备及热分解非等温动力学

Preparation and Kinetics of Thermal Decomposition of Silver Peroxide Decorated Diatomite-Based Porous Ceramic Composite

采用化学氧化法,以过硫酸钾为氧化剂制备了AgO修饰硅藻土基多孔陶瓷复合材料,用XRD、XPS、压汞仪对制备的复合材料进行表征,借助热重法和线性升温理论对复合材料的热分解过程和热分解动力学进行研究。结果表明,AgO修饰硅藻土基多孔陶瓷复合材料具有晶体结构,主要由正方晶系方石英和单斜晶系AgO组成;复合材料平均孔直径为3.862μm,中值孔直径为0.354μm,表观密度为1.794 g.mL-1,孔隙率为57.985%;复合材料中AgO的分解分两步,在158℃开始分解成Ag2O,更高温度时进一步分解成Ag;AgO分解服从核生成和核成长机理,其表观活化能为136.94 kJ.mol-1,反应频率因子为2.48×1014 s-1。同参比AgO粉末相比,复合材料中AgO的热稳定性提高。

Silver peroxide decorated diatomite-based porous ceramic composite was prepared by chemical oxidation method using potassium persulfate as oxidant and characterized by X-ray diffraction,X-ray photo electron spectroscopy and mercury injection apparatus.The process and kinetic behavior of thermal decomposition of the composite prepared were studied by means of thermogravimetry and linear temperature theory.The results show that the silver peroxide decorated diatomite-based porous ceramic composite prepared has crystal structure and is mainly made up of tetragonal christobalite and monoclinic silver peroxide.And the average pore diameter,median pore diameter,apparent density and porosity of the composite are 3.862 μm,0.354 μm,1.794 g·mL-1 and 57.985% respectively.Silver peroxide in the composite decomposes at 158 ℃ along with the formation of silver oxide followed by decomposing into silver at higher temperature.The mechanism of decomposition reaction is random nucleation and subsequent growth（A1）,and the apparent activation energy and reaction frequency factor are 136.94 kJ·mol-1 and 2.48×1014 s-1,respectively.Compared with reference silver peroxide powders,the thermal stability of silver peroxide in the composite rises.