花生壳的热重-质谱分析及其反应动力学

采用热重-质谱联用(TG-MS)研究了氮气气氛中花生壳在不同升温速率(5,10和20℃/min)下的热解行为,分析得到了花生壳热裂解过程产生的小分子气相产物(CO2,CH4,H2,CO)随温度和升温速率变化的释放规律.结果表明:花生壳热裂解过程分为四个阶段,升温速率越大,花生壳热解的失重温度区间越宽,最大热解速率峰越陡峭.应用Flynn-Wall-Ozawa法得出花生壳热裂解过程不同转化率(0.2~0.8)下的活化能在57.3~88.6 k J/mol范围内.结合Achar微分法和Coats-Redfern积分法确定了该反应过程的机理函数表达式,将30种常用机理函数一一代入得出花生壳热裂解机理的最概然函数为球形对称的三维扩散Jander方程,反应级数为2级.

Thermogravimetric-Mass Spectrometry Analysis and Pyrolysis Kinetic of Peanut Shell

In the nitrogen atmosphere， simultaneous thermogravimetric-mass spectrometry(TG/MS) was used to study the pyrolysis behavior of peanut shell at different heating rates (5， 10 and 20℃/min)， and with the change of temperature and heating rates， the release rule of small molecule gas (CO₂， CH₄， H₂， CO) product was obtained by mass spectrometry analysis. Results showed that four stages appeared during pyrolysis process of peanut shell. Moreover， the greater the heating rate， the wider the weightlessness temperature range， and the steeper the maximum pyrolysis rate peak. The activation energy of peanut shell under different weight loss rates (0.2~0.8) ranged in 57.3~88.6kJ/mol by Flynn-Wall-Ozawa method. With Achar differential method and the Coats-Redfern integral method， it could be determined that pyrolysis process of peanut shell accords with the Jander equation after calculating 30 kinds of common mechanism function one by one， the reaction mechanism was three-dimensional uniformly spherical diffusion control. The reaction order was 2.