Abstract: To improve the semi-cokes utilization efficiency in multi generation technology of coal pyrolysis,the application of low temperature pyrolysis char to methane by one step process was proposed. The influence of pyrolysis conditions on"one step"methanation activity was investigated in this work. A series of semi-coke samples derived from pyrolysis of Erdos lignite were prepared grammed under different atmosphere and temperature using a tubular furnace. The surface chemical,microcrystalline structure and methanation activity of these semi-cokes were investigated by means of Fourier transform infrared spectrometer(FTIR),X-ray diffraction (XRD) and a fixed-bed reactor. The results demonstrated that the interaction of H₂O with the lignite could weaken the loss of the oxygen-containing functional groups and restrain the graphitization process of semi-cokes. Thereby,the semi-cokes with higher content of oxygen-containing functional groups and lower graphitization degree were observed under H₂O ambiance compared with those in N₂ and H₂ atmosphere. In the range of 773K to 873K under H₂O atmosphere,the pyrolysis reaction proceeded more deeply with increasing temperature,which led to fewer oxygen functional groups and higher graphitization degree in the semi-cokes. As a result,the CH₄ accumulation was reduced. The optimal pyrolysis condition for methanation reactivity was under H₂O atmosphere at 773K,which was of great significance to optimize the co-production of pyrolysis and gasification process of low rank lignite.

Key words: pyrolysis condition, lignite semi-coke, methanation, one step method

摘要： 为提高褐煤热解多联产技术中半焦的利用效率，本文提出将低温热解半焦用于"一步法"制甲烷技术，考察了热解条件对半焦性质和一步甲烷化活性的影响。利用管式炉制备了不同气氛和温度的褐煤热解半焦，采用傅里叶红外光谱、X射线衍射技术和固定床反应器，对半焦表面化学、微晶结构和甲烷化活性进行了表征。结果表明，与N₂和H₂氛围相比，褐煤在水蒸气氛围中进行热解，半焦表面含氧官能团受到保护而含量更高，同时石墨化程度因受阻而降低，甲烷化活性更高；在水蒸气氛围中，773～873K范围内，随着热解温度升高，褐煤裂解反应进行程度加深，半焦表面含氧官能团数量降低，石墨化程度增加，致使甲烷化活性降低。总之，在水蒸气氛围中，773K时热解形成了一步甲烷化反应活性最好的褐煤半焦，对于低阶褐煤热解过程与气化过程优化联产具有重要指导意义。

关键词: 热解条件, 褐煤半焦, 甲烷化, 一步法