基于TG-FT IR分析的木屑热解机理

采用热重 红外联用（TG-FT IR）方法考察了木屑的热解规律，选择Kissinger和Ozawa 2种算法对木屑热解动力学参数进行估算，并采用固定床实验装置考察了木屑热解反应温度对产物分布的影响。结果表明，在不同升温速率及热解终温为950℃的热解条件下，木屑底物的失重率维持在77%～83%，且热解产物以气相产物为主，包括CO₂、CH₄、CO等；当温度高于200℃时，底物出现明显的热解过程，最高失重率下对应的温度随着升温速率的增加而升高。Kissinger和Ozawa 2种算法得出木屑热解反应活化能E分别为130.14和133.21 kJ/mol，频率因子lnA分别为  26.28和26.47 min^-1。木屑热解较理想的热解温度应控制在700℃以上，此时热解产物以CO、CO₂、CH₄、H₂气体为主；随着温度的升高，CO体积分数迅速下降，H₂体积分数迅速上升，CO₂和CH₄的体积分数基本不变。木屑固定床热解实验结果与其TG-FT IR的结果基本一致。

Pyrolysis Mechanism of Sawdust Based on TG-FT IR Analysis

Pyrolysis of certain sawdust was studied by using thermogravimetric analyzer coupled with Fourier transform infrared spectroscopy (TG-FT IR). The dynamics parameters of sawdust pyrolysis were calculated by the methods of Kissinger and Ozawa, respectively. Large-scale experiment of sawdust pyrolysis was conducted in the fixed bed device. With different heating rates and at the final temperature of 950℃, a total loss mass fraction of 77%-83% was observed. The temperature trend of evolving gaseous products, such as CH₄, CO and CO₂ was investigated. At a temperature above 200℃, the pyrolysis of sawdust was clearly accelerated and the maximum temperature corresponding to the pyrolysis shifted to high temperature with the increase of heating rates. The activation energy of sawdust was of 130.14 and 133.21 kJ/mol, respectively, and the frequency factor(lnA) of 26.28 and 26.47 min^-1 calculated by Kissinger and Ozawa methods. The optimal sawdust pyrolysis temperature was above 700℃ with CO, CO₂, CH₄ and H₂ as the main pyrolysis products. With the increase of temperature, the volume fraction of CO decreased rapidly while the volume fraction of H₂ increased evidently, and the volume fractions of CO₂ and CH₄ maintained relatively unchanged during the pyrolysis. The results obtained by the experiment in fixed bed device were consistent with the results of TG-FT IR experiment.