摘要
研究不同升温速率（β=5、10、20、40 K/min）下羟基酪醇的热稳定性、分解动力学和贮存期。利用热重分析得到羟基酪醇在氮气氛围中不同升温速率（β）下的热分解曲线,运用3种多升温速率法Kissinger法、Friedman法和Flynn-Wall-Ozawa法以及2种单升温速率方法 Coats-Redfern法和Achar法进行动力学分析,计算热分解的表观活化能（Ea）和指前因子（A）,且根据Ea和A推算羟基酪醇的贮存期。结果显示：羟基酪醇的热分解过程一步完成,在升温速率为10 K/min时,从260-409℃为羟基酪醇的主要失重阶段;TG曲线随着温度的升高而迅速出现陡峭明显的失重台阶,DTG曲线亦出现负值,且随着温度的升高而急剧下降,在305.2℃达到了DTG的峰值,此时达到最大热失重速率为-12.91%/min;升温速率的变化对羟基酪醇的分解有影响,随着速率的升高,羟基酪醇的热分解温度逐渐升高,热分解曲线略微向高温移动,呈现了分解滞后现象。羟基酪醇的热分解机制符合一维扩散（D1）模型。测得平均Ea为122.40 k J/mol,A为3.37×1010min-1。根据Ea和A可推断,在室温25℃下,羟基酪醇在氮气氛围下的理论贮存期为4-5年。
The thermal stability decomposition kinetics and shelflife of hydroxytyrosol were studied at different heating rates （β=5, 10, 20, 40 K/min）. Thermal decomposing curves were obtained in the nitrogen atmosphere by TG analysis. Five thermal analysis kinetic methods of multi-heating rate methods（ Kissinger, Friedman, Flynn-Wall-Ozawa） and single heating rate methods （Coats-Redfern and Achar） were used to speculate the probable mechanism of thermal decomposing reaction and the kinetic parameters including activation energy Ea and pre-exponential factor A. The shelflife of hydroxytyrosol at room temperature （25 ℃ ） was calculated by the kinetic parameters. The TG curve showed the decomposition of hydroxytyrosol was finished by one step, and the temperature of 260-409 ℃ was the main thermal decomposition stage at the heating rate of 10 K/min. With the increase of temperature, the steep and obvious weight loss occurred rapidly in the TG analysis. The DTG curve presented as negative value and decreased rapidly with the maximum loss ratio of - 12.91%/min at 305.2℃. With the increase of the heating rate, thermal decomposing temperature of hydroxytyrosol rose, the thermal decomposing curves moved toward high temperature slightly and the decomposition showed hysteresis phenomenon. The probable kinetic mechanisms of thermal decomposition were one-dimensional diffusion. The average apparent activation energy （Ea ） was 122. 40 kJ/mol and preexponential factor （A） was 3.37 × 10^10 min-1. The theoretical shelflife of hydroxytyrosol at room temperature was about 4-5 years in the nitrogen atmosphere.
出处
《林产化学与工业》
EI
CAS
CSCD
北大核心
2016年第6期87-92,共6页
Chemistry and Industry of Forest Products
基金
甘肃省科技重大专项(143NKDK025)
国际科技合作专项项目(2014DFR31300)
关键词
羟基酪醇
热分析
热重
热分解动力学
贮存期
hydroxytyrosol
thermal analysis
thermogravimatry
thermal decomposition kinetics
shelflife
