3种烟草材料的热特性、动力学和热力学研究

Kinetics and thermodynamic parameters of three kinds of tobacc Omaterials

为深入了解烟草材料的热解过程的反应机理,研究了非等温条件下3种烟草材料(HS、烤烟K326和FP)的热特性、动力学和热力学。TGA实验表明,3种烟草材料的热解特性有很大差异。由综合热解指数反映,3种烟草材料三个主要热解阶段的热解指数均逐渐降低。StageⅡ时,K326和FP容易热解。相反,在StageⅢ和Ⅳ,HS较容易热解。采用模型拟合法Coats-Redfern计算了3种烟草材料主要热解阶段的动力学三参量(Ea、A和g(α))。动力学分析表明,HS的反应模型分别为F3、D1和F3。烤烟K326的反应模型分别为:D1、F2和D1。FP的反应模型分别为:D3、F3和D1。由过渡态理论确定了热力学参数(ΔH,ΔG,ΔS)。特征温度下的正ΔH、正ΔG和负ΔS验证了烟草材料的热解是吸热、非自发过程。

In order tOunderstand the reaction mechanism of the pyrolysis process of tobaccOmaterials,the thermal conversion characteristics,kinetics,and thermodynamics of three kinds of tobaccOmaterial,were investigated under non-isothermal conditions.TGA experiments showed that the pyrolysis characteristics of three kinds of tobaccOmaterial were quite different.It is reflected by the composite pyrolysis index P that the pyrolysis index of three main pyrolysis stages of three kinds of tobaccOmaterials were gradually decreased.The kinetic triplets of the main pyrolysis process of agricultural residues were calculated by the model-fitting method(C-R).Kinetic analysis results indicated:the most potential kinetic models for the pyrolysis of HS were F3,D1 and F3,respectively.The most potential kinetic models for the pyrolysis of Flue-cured tobaccOK326 were D1,F2 and D1.The most potential kinetic models for the pyrolysis of FP were D3,F3 and D1.The thermodynamic parameters(ΔH,ΔG,andΔS)were determined by the activated complex theory.The positiveΔH,positiveΔG,and negativeΔS at characteristic temperatures validated that the pyrolysis of agricultural residues was endothermic and non-spontaneous.