玉米芯热解及过程分析

玉米芯热解及过程分析

  • 摘要: 研究了农业废弃物玉米芯热解过程中气、液、固三相产率与裂解温度的关系;气相组成、液相组成与温度的关系,以及热解过程的机理。实验表明,在350℃~400℃,气相成分主要是CO2、CO所占比率为95%;随着温度的升高,H2、C2H4、CH4等气体的比率逐渐增高,CO、CO2的体积分数在逐渐降低。在450℃~500℃,CO、H2所占的比率达50%。GCMS,IR分析表明,裂解过程产生的液体主要是由含氧的化合物酚、呋喃及其衍生物组成;低温有利于酚类质量分数的增加,高温有利于4-乙基-2-甲氧基-苯酚、2-甲基-苯酚的增加;采用TGA分析,建立了热解过程的动力学方程,得到了热解过程的反应机理,即热解过程有两个分解阶段,在不同温度段具有不同的反应规律。在211℃~290℃具有三级反应的特征,其活化能为121.4kJ·mol-1;在290℃~418℃表现为0.5级反应的特征,其活化能为105.7kJ·mol-1。

     

    Abstract: In order to utilize the agricultural waste corncob comprehensively and effectively, the composition of gaseous and liquid products and the kinetics of pyrolytic process have been investigated. The experimental results show that the gases are mainly composed of CO2 and CO at 350 ℃~400 ℃ which account for nearly 95%. When the temperature is further increased, the yields of CO2 and CO are gradually decreased, but the yields of H2, C2H4, CH4, C3H6 and C3H8 are gradually increased. The gases have nearly 50% of CO and H2 at 450 ℃~500 ℃. The composition of liquid produced during pyrolytic process is analyzed by GC-MS and IR, which reveals that the oxygenated organic compounds such as phenol, furanmethanol, etc. are the main components and a lower temperature benefits the formation of phenol and its derivatives. The analysis of kinetics with TGA elucidates that the pyrolytic process includes two steps. For the first step in the temperature range 211 ℃~290 ℃, the pyrolysis reaction is third order, and it is a half order for the second step at 290℃~418℃, which have the activity energy of 121.47kJ·mol-1 and 105.7kJ·mol-1, respectively.

     

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