氮气气氛下玉米淀粉热分解动力学参数

为确定玉米淀粉热分解反应的化学动力学参数,在氮气气氛下以5,10,15℃/min升温速率对其进行了热重分析.结果表明:玉米淀粉受热过程可分为3个阶段;升温速率不同,各阶段的起始与终止温度存在差异;阶段Ⅰ起始温度为25℃,终止温度为125~146℃,阶段Ⅱ起始温度为266~274℃,终止温度为341~373℃,阶段Ⅲ的开始温度为342~378℃,终止温度为427~520℃;在阶段Ⅱ中玉米淀粉的热分解较为明显,反应的活化能为324.3~355.9 kJ/mol,反应级数为1.6~2.1;动力学参数计算的淀粉失重预测值与实验值一致性较好.

Kinetic Parameters of Maize Starch in Nitrogen Atmosphere

Thermogravimetric analysis was performed at heating rates of 5,10,and 15 ℃/min in nitrogen atmosphere to determine the thermal degradation kinetic parameters of maize starch.There are three stages of weight loss in the whole thermal process.The start and end temperatures in each stage are different at different heating rates.The temperature range was 25 to 125～146 ℃ in stage Ⅰ.For stage Ⅱ and Ⅲ,the temperature was from 266～274 ℃ to 341～373 ℃ and 342～378 ℃ to 427～ 520 ℃,respectively.There is an observable decomposition in stage Ⅱ in which the corresponding activation energy is 324.3～355.9 kJ/mol and the reaction order is 1.6～2.1.The predicted values of weight loss agree with the experimental results.