摘要
采用不同的升温速率,通过非等温热重法研究了氢氧化镧在氮气气氛中的热分解动力学。该氢氧化物在氮气气氛中为两步分解,第一阶段是氢氧化镧失去一分子水分解为羟基氧化镧,第二阶段是由羟基氧化镧失去一分子水分解为三氧化二镧。使用Flynn-Wal1-Ozawa和Kissinger-Akahira-Sunose等转化率法求出两阶段分解的活化能,同时利用Achar-Brindley-Sharp微分方程和Coats-Redfern积分方程研究了其热分解机理。结果表明,在0.20至0.80的转化率范围内,氢氧化镧在氮气气氛下第一阶段的热分解活化能为155.6 k J·mol-1,机理方程符合收缩球状方程;第二阶段的热分解活化能为192.9 k J·mol-1,机理方程符合收缩圆柱体方程。
The thermal decomposition kinetics of lanthanum hydroxide was studied by non-isothermal thermogravimetry in a nitrogen atmosphere at different heating rates. The first stage is the dehydration of water producing LaOOH, the second stage is the transformation of LaOOH to La2O3. The two step decomposition activation energy was calculated by using Flynn-Wall- Ozawa （FWO） and Kissinger-Akahira-Sunose （KAS） conversion method. In the meantime, the thermal decomposition mechanism was investigated by using Achar-Brindley-Sharp differential equation and Coats-Redfern integral equation. The results show that, within the scope of 0.2 to 0.8 conversion rate, the thermal decomposition activation energy of the first step is 155.6 kJ·mol-1 , and mechanism equation is in conformity with the contract globular equation; the thermal decomposition acti- vation energy of the second step is 192.9 kJ· mol- ,which conform to the shrinkage of cylinder mechanism equation.
出处
《稀土》
EI
CAS
CSCD
北大核心
2015年第4期116-119,共4页
Chinese Rare Earths
基金
辽宁省自然科学基金项目(201202122)
关键词
氢氧化镧
热分解
活化能
机理函数
lanthanum hydroxide
thermal decomposition
activation energy
mechanism of function
