高温下热解温度对煤焦孔隙结构的影响

利用高温沉降炉在1500K～1800K制备京西无烟煤煤焦，使用化学吸附法测定不同热解温度下煤焦比表面积及孔容积与孔径的分布特征，并采用SEM观察煤焦颗粒表面的形态，分析了高温下热解温度对煤焦孔隙结构的影响规律。结果表明，煤焦的比表面积主要由孔径小于10nm的微孔和中孔构成，而其孔容积则主要由孔径为2nm~50nm的中孔构成。高温下煤焦比表面积和孔容积随热解温度的升高，呈现先增大后减小的非单调变化现象，转折温度约为1600K。出现这种变化的主要原因是煤焦在热解温度超过1600K后开始烧结，产生较为光滑致密的表面结构，部分孔隙封闭。

Effect of pyrolysis temperature on porous structure of anthracite chars produced at high temperatures

An experimental study was conducted on the porous structure of the char particles of JX anthracite by using nitrogen absorption method.The coal chars were produced under high temperatures ranging from 1 500 K to 1 800 K in a drop tube furnace.The distributions of specific surface area and pore volume with pore diameter were derived by using BET and BJH methods.It is found that the pores in micro-size and meso-size are major contributors for the overall specific surface area and pore volume.Furthermore,with the increasing of pyrolysis temperature,the specific area and pore volume vary in the shape of mountain and the temperature of peake is around 1 600 K.The SEM observation shows that the surface of char particles becomes smoother and denser when the pyrolysis temperature is higher than 1 600 K.It is suggested that the melting of internal ash during high temperature pyrolysis is the main cause for such a phenomenon,and thus the turning point is related to the melting point of the char.