油脂氢化反应活化能的测定原理

采用油脂氢化中氢原子碰撞反应理论的基本观点,本文从理论上给出了油脂氢化反应活化能的测定原理。在指定氢化温度下测定不同氢化时间后氢化油的碘价,可求出该温度下单烯酸(酯)的氢化反应速率常数。根据Arrhenius公式,用不同温度下的速率常数的对数对1/T作图,即可计算出单烯酸(酯)反应的活化能E_1。以氢化油脂肪酸组分的分析结果,按本文公式作图或计算也可得到三烯酸(酯)、二烯酸(酯)的氢化反应活化能E_3和E_2。选用自制催化剂、高纯氢气、精制豆油进行油脂氢化实验,对测定原理做了进一步验证和应用。测定结果,豆油的活化能E_2=341.22kJ/mole、E_1=79.51kJ/mol。

THE PRINCIPLE OF DETERMINING ACTIVATION ENERGY FOR THE HYDROGENATION REACTIONS IN OILS AND FATS

According to the basic view of hydrogenatom collision theory of oil and fat hydrogena-tion, a simple method of determining activation energy is obtained for the reactions. At the proper hy-drogenation tempreture, the reaction rate constant (CHki) of oleate can be known by measuring the decrease of iodine value at different reaction time. Then the activation energy E1 of oleate hydrogenation reaction is easily obtained from the linear slope of serial LnCHnk1(T) versus 1/T. The activation energy E2 of linoleate hydrogenation and ES of Hnolenate reaction can be also determined by plotting and calculating with formula in the paper from the fatty acid composition of hydrogenated oils on the different reaction level. The above methods are proved by the hydrogenation experiments with refined soybean oil and self-made nickel/silica catalyst in the selected conditions. The results of activation energy of soybean oil determined are:E2 = 341. 22KJ/mole and E1 = 79. 51KJ/mole.