甲硫氨酸的非等温热分解动力学的研究  

Study on Non-Isothermal Decomposition Kinetics of Methionine

作　　者：牛芊 周彩荣[1] 詹自力[1] NIU Qian;ZHOU Cai-rong;ZHAN Zi-li(School of Chemical Engineering and Energy,Zhengzhou University,Zhengzhou 450001,China)

机构地区：[1]郑州大学化工与能源学院,河南郑州450001

出　　处：《高校化学工程学报》2018年第5期1112-1118,共7页Journal of Chemical Engineering of Chinese Universities

基　　金：河南省教育厅重点科技攻关项目(13A530712)

摘　　要：以热重分析法(DTA-TGA)对甲硫氨酸的热分解行为及其动力学规律进行了考察研究。研究结果表明甲硫氨酸在熔融过程中伴随着分解反应。在氮气气氛下使用DTG-60和DSC-60热分析仪,升温速率分别控制为5、10、15、20、25K·min^(-1),实时在线分析甲硫氨酸样品的TG-DTA曲线,运用Flynn-Wall-Ozawa积分法、Kissinger最大速率法和?atava-?esták积分法对甲硫氨酸的热分解动力学参数进行了计算,并得出甲硫氨酸热分解反应的表观活化能Es为155.59kJ×mol^(-1),指前因子的对数值lg As为194.06min^(-1)。确定出甲硫氨酸热分解反应的机理为化学反应,并得到热分解机理函数的积分式G(α)=-ln(1-α)。此外,热分解动力学分析的结果表明,在热分解过程中,焓变ΔH为1604.52kJ×mol^(-1),熵变ΔS为1787.7J×mol^(-1)×K-1,吉布斯自由能的变化ΔG为618.437 kJ×mol^(-1)。甲硫氨酸的非等温热分解动力学的研究为甲硫氨酸的进一步开发利用提供了数据支持。Thermal stability and decomposition kinetics of methionine under nitrogen atmosphere were investigated by DTA-TGA. The results show that the melting process of methionine is accompanied by decomposition. When studied using DTG-60 and DSC-60 at different heating rates of 5, 10, 15, 20, 25 K·min^-1, the calculated activation energy（Es） and pre-exponential factor（lg As） via Flynn-Wall-Ozawa, Kissinger and ？atava-？esták methods are 155.59 kJ×mol^-1 and 194.06 min-1, respectively. The mechanism of the thermal decomposition was through chemical reaction and the integral equation G（α） =-ln（1-α） was obtained. Moreover, thermodynamic results show that enthalpy change ΔH, entropy change ΔS and the change of Gibbs free energy ΔG are 1604.52 kJ×mol^-1, 1787.7 J×mol^-1×K^-1 and 618.437 kJ×mol^-1, respectively. This study provides fundamental data for further development and utilization of methionine.

关 键 词：甲硫氨酸 热分解 非等温热分解 动力学 热失重-差热分析 

分 类 号：O642[理学—物理化学]