摘要
利用热重(TG)分析技术对六氨氯化镁的热分解过程及动力学进行了研究,考察了六氨氯化镁在4、7、10、13、16K·min-1线性升温速率和空气气氛下热分解机理,六氨氯化镁热解过程分为3个阶段。提出了一种整体优化的多升温速率迭代的等转化率求取活化能方法,采用该方法,得到六氨氯化镁热解3个阶段的活化能分别为51.38、64.70、73.55kJ·mol-1。采用整体优化的多升温速率等温法确立了六氨氯化镁热解3个阶段的热解机理函数与指前因子:第1步反应的热解机理属于固体相边界反应机理(n=1/4),指前因子为3.281×105s-1;第2步反应的热解机理属成核与生长机理(n=1.8),指前因子为5.624×106s-1;第3步反应属化学反应机理(1.5级反应),指前因子为5.862×105s-1。
Thermal decomposition and non-isothermal kinetic evaluation of magnesium chloride hexammoniate （MgCl2·6NH3） were studied with thermogravimetric analysis （TGA） . The decomposition mechanism of MgCl2·6NH3 was investigated at five heating rates of 4, 7, 10, 13 and 16 K·min^-1 with an air flow of 50 ml·min^-1 . The results showed that the thermal decomposition of MgCl2·6NH3 was divided into three stages. A globally optimized iterative iso-conversion method was proposed to calculate the activation energy of thermal decomposition. The calculated activation energies of MgCl2·6NH3 at each thermal decomposition stage were 51.38, 64.70 and 73.55 kJ·mol^-1 respectively. The most probable decomposition mechanism functions and pre-exponential factors corresponding to each stage of thermal decomposition of MgCl2·6NH3 were derived. The thermal decomposition of MgCl2·6NH3 at the first stage belonged to the phase boundary reaction （n= 1/4）, and the corresponding pre-exponential factor （A） was 3.281×10^5 ·s^-1. The thermal decomposition mechanism of MgCl2·6NH3 at the second stage belonged to the nucleation and growth mechanism （n= 1.8）, and A was 5.624×10^6 ·s^-1. The thermal decomposition mechanism of MgCl2·6NH3 at the third stage belonged to the chemical reaction mechanism （n=1.5）, and A was 5.862×10^5 ·s^-1.
出处
《化工学报》
EI
CAS
CSCD
北大核心
2008年第9期2255-2259,共5页
CIESC Journal
基金
国家"十五"科技攻关计划项目(2004BA311A08)
上海市重点学科建设项目(B506)
关键词
热分解
非等温动力学
六氨氯化镁
热重分析
thermal decomposition
non-isothermal kinetics
magnesium chloride hexammoniate
thermogravimetric analysis
