升温速率对椰壳热解特性的影响及动力学分析

    Kinetic analysis and pyrolysis characteristics of coconut shells at different heating rates

    • 摘要: 利用热重分析仪对椰壳在不同升温速率(5、20、40℃/min)下的热解特性及动力学进行了研究,探讨了热解机理。结果表明:椰壳热解过程主要分为脱水、快速热解和缓慢失重;对比不同升温速率下的失重曲线表明,升温速率对热解失重率有明显影响,其最终热解产物的得率随升温速率的增加而减少。运用氮吸附仪测定其吸附等温线,获得不同热解温度对炭化料的孔结构,结果表明:热解温度越高,微孔越发达。使用TG曲线数据,利用分布活化能模型求出相应的活化能,失重率在0.1~0.8之间时,活化能在146~444 kJ/mol,呈“N”形变化。活化能的分布函数,反映了椰壳热解过程中不同阶段反应性能的变化规律,有助于了解椰壳的热解机理。

       

      Abstract: The pyrolysis characteristics and kinetics of coconut shells were investigated via thermo-gravimetric analysis (TGA) at different heating rates (5, 20, 40℃/min), and the pyrolysis mechanism was explored. The distributed activation energy model (DAEM) was used to study the pyrolysis kinetics. The experimental results reveal that the pyrolysis process includes three stages: dehydration, rapid pyrolysis and slow weight-loss. When heating rate increases, the maximum rates of mass losses increase clearly and yield of chars decreases. N2 adsorption isotherms of chars prapared under different pyrolysis temperatures show that the higher pyrolysis temperature is, the more developed chars’ microporosity is. When the weight loss rate attains between 0.1 and 0.8, the activation energies of samples are between 146-444 kJ/mol, whose curves are not monotonously increasing, but show “N” shape, The distribution function of activation energy reveals changes of the reaction properties of mass in different stages of pyrolysis, which helps to investigate the pyrolysis mechanism of coconut shells.

       

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