Co-pyrolysis experiments with low metamorphic coal (LC) and pine sawdust (PS) were carried out in a fixed-bed pyrolysis reactor. The effect of biomass addition on the yield distribution and composition of the coal pyrolysis products was investigated. The pyrolysis behavior was studied by thermogravimetric analysis. The Coats–Redfern integral and Achar differential methods were used to study the mechanism functions and the kinetic parameters of the pyrolysis process of each sample. The results show that there is a synergistic effect on the co-pyrolysis and it is most pronounced at a PS mixing ratio of 30%, and it results in improved tar and gas yields. Part of the polycyclic aromatic hydrocarbons (PAHs) in the co-pyrolysis tar are converted into phenolic substances with a simple structure, which improves the quality of the tar. At the same time, the alcohols and acids in the PS and LC react to generate a large number of esters. The addition of PS shifted the LC pyrolysis process towards the low temperature region, lowering the pyrolysis temperature of the coal sample and increasing the pyrolysis rate of the sample. The main pyrolysis process of LC conforms to the second-order chemical reaction law with an activation energy of 35.93 kJ mol⁻¹, and the main pyrolysis process of PS conforms to the one-dimensional diffusion parabolic law with an activation energy of 63.84 kJ mol⁻¹, and the main pyrolysis process of LC and PS co-pyrolysis conforms to a second-order chemical reaction law with an activation energy of 86.19 kJ mol⁻¹.

中文翻译：

---

低变质煤与松木屑的共热解特性及动力学

在固定床热解反应器中进行了低变质煤（LC）和松木屑（PS）的共热解实验。研究了生物质添加对煤热解产物产率分布和组成的影响。通过热重分析研究热解行为。Coats-Redfern积分法和Achar微分法用于研究每个样品热解过程的机理函数和动力学参数。结果表明，共热解具有协同效应，并且在PS混合比为30%时最明显，从而提高了焦油和煤气的收率。共热解焦油中的部分多环芳烃（PAHs）转化为结构简单的酚类物质，提高了焦油的质量。同时，PS和LC中的醇和酸反应生成大量酯。PS的加入使LC热解过程向低温区移动，降低了煤样的热解温度，提高了样品的热解率。LC的主要热解过程符合二级化学反应定律，活化能为35.93 kJ mol^-1，PS的主热解过程符合一维扩散抛物线定律，活化能为63.84 kJ mol ^-1，LC和PS共热解的主热解过程符合二级化学反应活化能为 86.19 kJ mol ^-1的定律。