迪开石热分解及重结晶的非等温动力学  

Non-isothermal Kinetics for Thermal Decomposition and Recrystallization of Dickite

作　　者：曾远[1] 何明中[1,2] 周佳[1] 雷雯[1] 傅凤英[1] 

机构地区：[1]中国地质大学(武汉)材料与化学学院 [2]纳米矿物材料及应用教育部工程研究中心,武汉430074

出　　处：《高等学校化学学报》2011年第12期2865-2871,共7页Chemical Journal of Chinese Universities

基　　金：国家自然科学基金(批准号:50972135)资助

摘　　要：采用热分析(TG-DTG-DSC)和X射线衍射(XRD)技术研究了福州迪开石在动态空气气氛条件下的热分解及重结晶过程,利用TG和DSC数据分别对迪开石的热分解和重结晶过程进行动力学分析.由Friedman法求得热分解过程的表观活化能,以此为初始值,通过非线性回归法拟合得到了热分解过程最可能的反应机理和动力学参数;将迭代的等转化率法和最小偏差法相结合计算得到了高温下迪开石重结晶过程最可能的反应机理和动力学参数.研究结果表明,迪开石在450～750℃内发生热分解,脱去2个水分子,生成无定形的准迪开石,此过程为两步连串反应,第一步为随机成核和随后生长机理An,第二步为自催化反应机理CnC;在975～1050℃内,准迪开石重结晶转化为莫来石,此过程对应的反应机理为An.The processes of the thermal decomposition and recrystallization of dickite from Fuzhou,Fujian Province have been studied in dynamic air atmosphere by a simultaneous thermal analysis instrument（thermogravimetric analysis-derivative thermogravimetric analysis-differential scanning calorimetry,TG-DTG-DSC） and X-ray diffraction techniques.The data of TG and DSC were used to carry out the kinetic triplet of the thermal decomposition and recrystallization,respectively.The Friedman method together with the non-linear regression approach was employed to determine the reaction mechanism and the kinetic parameters of the thermal decomposition.The iterative procedure and minimum deviation were used to determine the reaction mechanism and the kinetic parameters of the recrystallization.The results show that the thermal decomposition（dehydrate 2 molecules of water） of dickite occurs in the temperature range of 450—750 ℃ and the reaction mechanisms contains two steps continuously.The process conforms to a random nucleation and nuclei growth model（An） and auto-catalytic model（CnC）.The recrystallization of dickite appears in the temperature range of 975—1050 ℃.The reaction mechanism is best described by the random nucleation and nuclei growth model（An）.

关 键 词：迪开石 热分解 重结晶 非等温动力学 非线性拟合 

分 类 号：O643.12[理学—物理化学]