Abstract:

Thermogravimetric infrared linkage technology(TG-DTG-FTIR) was used to study the pyrolysis characteristics of monounsaturated free fatty acid oleic acid components in rubber seed oil at different heating rates (5℃/min, 10℃/min, 20℃/min, 30℃/min).Then, the characteristic parameters obtained by non-isothermal pyrolysis of oleic acid were studied and calculated by multiple linear regression method, and the corresponding reaction series, activation energy and pre-exponential factor were obtained under different heating rates, and the activation energy and pre-exponential factor of oleic acid pyrolysis under different heating rates were fitted linearly. The experimental results show that the pyrolysis process of oleic acid can be divided into two stages: 0—268℃ and 268—300℃. According to the analysis of the characteristic peak of the infrared spectrum, steam, CH₄, CO₂ and CO volatilized during the thermal decomposition of oleic acid at different heating rates. As the heating rate increases, the maximum weight loss rate of oleic acid pyrolysis increases, and the pyrolysis interval moves towards the high-temperature section. Meanwhile, when the heating rate is from 5℃/min to 30℃/min, the reaction series n=1, the activation energy of thermal decomposition reaction decreases from 105.57kJ/mol to 93.99kJ/mol, and the pre-exponential factor decreases from 6.99×10⁶ to 6.7×10⁵.When n≠1, the activation energy of the thermal decomposition reaction decreased from 102.45kJ/mol to 93.38kJ/mol, and the pre-exponential factor decreased from 3.13×10⁶ to 2.97×10⁴. The activation energy of the reaction and the pre-exponential factor decreased significantly with the increase of the heating rate. By linear fitting of activation energy and exponential factor of oleic acid pyrolysis reaction at different heating rates, it is found that the two have a good compensation effect.

Key words: rubber seed oil, oleic acid, thermogravimetric infrared analysis, pyrolysis, kinetics

摘要：

利用热重红外联动技术（TG-DTG-FTIR）研究了橡胶籽油中的单不饱和游离脂肪酸油酸组分在不同升温速率（5℃/min、10℃/min、20℃/min、30℃/min）下的热解特性。然后，用多元线性回归法对油酸非等温热解所得到的特性参数进行研究并计算，求得不同升温速率下对应的反应级数、活化能和指前因子，并对不同升温速率下油酸热解反应活化能和指数前因子作线性拟合。结果表明：油酸热解过程主要可分为0～268℃和268～300℃两个阶段，由红外谱图特征峰的分析可知，不同升温速率下，在油酸热解的阶段内均出现了水蒸气、CH₄、CO₂和CO这4种主要气体挥发分。随着升温速率的增大，油酸热解的最大失重速率随之增大，热解区间也向着高温段移动，同时计算在升温速率从5～30℃/min的过程中，反应级数n=1时，热解反应活化能由105.57kJ/mol降低至93.99kJ/mol，指数前因子由6.99×10⁶降低至6.7×10⁵；n≠1时，热解反应活化能由102.45kJ/mol降低至93.38kJ/mol，指数前因子由3.13×10⁶降低至2.97×10⁴，反应活化能和指数前因子随升温速率的增大出现明显减小。通过对不同升温速率下油酸热解反应的活化能和指数前因子进行线性拟合后发现，两者间具有较好的补偿效应。

关键词: 橡胶籽油, 油酸, 热重红外分析, 热解特性, 动力学