高温下煤焦的碳微晶及孔结构的演变行为

以贵州煤为原料,在热解温度950℃~1400℃制备了各种慢速和快速热解焦,主要对高温热解过程中煤焦的碳微晶和孔结构的演变行为进行了研究,同时也研究了高温气化过程中煤焦的孔结构变化规律。结果表明,慢速热解焦和快速热解焦的C和H含量明显不同;随热解温度的升高,煤焦的碳微晶结构向有序化方向发展,但慢速热解煤焦比快速热解煤焦的"石墨化"程度大;快速热解煤焦的微孔比表面积和微孔容积明显高于慢速热解煤焦,即快速热解煤焦的孔隙结构明显比慢速热解煤焦发达;在气化反应初期,煤焦的微孔比表面积下降,微中孔比表面积增加,反应后期煤焦的总比表面积快速下降。

Evolvement behavior of carbon minicrystal and pore structure of coal chars at high temperatures

The various slowly and rapidly pyrolyzed chars were prepared with Huainan coal and Guizhou coal at pyrolysis temperatures of 950℃～1400℃, and the evolvement behavior of carbon mincrystal and pore structure of coal chars was investigated during high temperature pyrolysis process. At the same time, the evolvement of pore structure of coal chars was studied. The content of carbon and hydrogen of slowly pyrolyzed chars (SPC) is obviously different from those of rapidly pyrolyzed chars (RPC). As the pyrolysis temperature increases, the carbon minicrystals of coal chars become more and more ordered. Besides, the ‘graphitization’ degree of SPC is larger than that of RPC. The micropore surface area and pore volume for RPC are obviously larger than those for SPC, indicating that the pores of RPC are much richer than those of RPC. In the initial gasification process of coal chars, the micropore surface area of coal chars decreases, while the micro- and meso-pore surface area of coal chars increases. In the end of coal char gasification process, the total surface area of coal chars decreases rapidly.