为认识1000℃以下制备的中低温煤焦与1000℃~1500℃高温条件下制备的高温煤焦结构及燃烧行为的不同,以陕西低阶烟煤为原料在管式炉上于800℃~1500℃制备了煤焦,利用扫描电子显微镜、物理吸附仪、元素分析仪、X射线衍射仪(XRD)等,揭示了不同煤焦在高温热解过程中形貌、孔结构、组成、晶体结构等物理化学结构方面的变化规律,采用热重分析仪研究了不同煤焦的燃烧特性。结果表明:随着热解温度升高,煤焦表面气孔先增多后减少,比表面积和孔体积先增大后减小,当热解温度为1100℃时达到最大值;随着热解温度由800℃升高至1500℃,煤焦的H含量逐渐降低,n(C)∶n(H)逐渐增大,C含量和热值呈现先增加再缓慢降低后基本不变的趋势,在热解温度为1000℃时达到最大值;热解温度越高,煤焦的综合燃烧特性指数越低,在1000℃~1300℃范围内煤焦综合燃烧特性指数随热解温度升高下降最明显;在热解温度高于1200℃时,煤焦燃烧的微分热重曲线和差热分析曲线出现明显的“双峰”现象,这归因于高温下煤焦结构变异形成了石墨,且XRD谱和拉曼光谱均表明热解温度越高,煤焦的石墨化程度越高。

To understand the difference in both structure and combustion behavior of charinvestigated by analyzing the surface morphology, pore structure, calorific value, and composi-tion. The combustion characteristics of different chars were scrutinized by a thermogravimetric analyzer (TGA). The results show that as the pyrolysis temperature increases, the pores on the char surface gradually increase and then decrease. The specific surface area and pore volume ex-perienced and increase and subsequent decrease before and after the pyrolysis temperature reach 1 100 ℃. With the pyrolysis temperature increasing from 800 ℃ to 1 500 ℃, the H content of chars gradually decreases, while n(C)∶n(H) gradually increases; the C content and calorific value exhibite a gradual rise, followed by a slow decline, ultimately reaching a relatively constant level. The higher the pyrolysis temperature, the lower the char’s comprehensive combustion characteristic index. The comprehensive combustion characteristic index of chars prepared at the pyrolysis temperature of 1 000 ℃-1 300 ℃ decreases most obviously with the increase of pyroly-sis temperature. The differential thermogravimetric curve (DTG) and differential thermal analy-sis (DTA) curve of char prepared above 1 200 ℃ combustion show distinct “double-peak” phe-nomenon, which is attributed to the structural variation of char above 1 200 ℃, resulting the for-mation of graphite. The results of XRD and Raman spectroscopy indicate that the higher pyroly-sis temperature will improve the growth of graphite microcrystalline structure.