热处理对煤焦反应性及微观结构的影响

用热天平和XRD考察了热处理对二种煤(河北蔚县褐煤、四川湔江烟煤)镜质组半焦微观结构和反应活性的影响。TGA结果表明，热处理温度增加，蔚县煤镜质组(YXV)与湔江煤镜质组(JJV)焦炭的反应性降低；YXV焦炭的反应性随着热处理时间的增加而急剧下降，但一定热处理时间(60 min)后，其下降趋势变缓；热处理时间对JJV焦炭的影响较小。XRD结果表明，在热处理温度为900 ℃，初焦热处理时间为60 min时，YXV焦炭晶格结构发生明显改变，900 ℃以上，YXV焦炭芳香堆垛高度Lc随着热处理时间的增加而增加；热处理时间对JJV焦炭的影响不如YXV显著，而只有在较高的热处理温度(1 200 ℃)下，碳的微观结构才出现明显的有序化。热处理导致的焦炭微观碳结构趋于有序化是焦炭反应性下降的主要原因。

Effect of heat treatment on the reactivity and microstructure of coal-char

The effect of heat treatment on the reactivity and microstructure of chars prepared from the vitrinites of two coals ( Yuxian lignite vitrinite (YXV) and Jianjiang bituminous coal vitrinite (JJV)) was investigated using X-ray diffraction(XRD) and Thermal Gravity Analysis(TGA). The results from TGA show that the reactivity of the chars from YXV and JJV decreases with the increase of heat treatment temperature. The reactivity of YXV char decreases quickly and significantly as the heat treatment time increases. However, after 60 min of heat treatment , it decreases slowly with time. The effect of heat treatment time on the reactivity of JJV char is slight. The results from XRD show that the microstructure of coal-char is determined by the intensity of heat treatment. When the heat treatment time is above 60 min, the structure of crystallites of YXV char prepared under 900℃ changes obviously and becomes more orderly. The aromatic layer stacking heights (Lc) of YXV char increase with the increase of heat treatment time when the heat treatment is conducted above 900℃. The effect of heat treatment time on Lc of JJV char is not significant, but under the heat treatment temperature of 1200℃, the crystalline of JJV char grows distinctly. There is a good parallel relationship between the crystalline growth and the deactivation of chars. It can be concluded that the growth of crystalline is the main reason for the deactivation of coal-char.