热解温度对无烟煤焦微观结构和脱硝特性的影响

在氮气气氛和600～1000℃条件下, 使用水平管式炉对龙坪无烟煤进行了热解制焦实验, 利用拉曼光谱分析了热解煤焦的微观结构变化, 使用热重分析仪(TGA)进行了无烟煤焦的程序升温脱硝实验, 研究了热解温度对无烟煤焦微观结构和脱硝特性的影响。研究结果表明:热解温度对无烟煤焦的微观结构有显著的影响, 随着热解温度升高, 煤焦的拉曼光谱G峰与D1峰的位置差逐渐减小, 谱峰积分面积逐渐缩小, 积分面积比值I_D1/I_G和I_D3/I_G先增大后减小, I_G/I_All先减小后增大。热解温度还对无烟煤焦的脱硝特性有明显的影响, 无烟煤随着热解温度升高由炭化向初步石墨化转变, 由于活性结构数量的减少和碳结构变得更加有序, 无烟煤焦的脱硝反应性不断降低, 脱硝反应活化能增大。

Effect of pyrolysis temperature on microstructure and de-NOx reactivity of anthracite char

The Longping anthracite was pyrolyzed in the temperature range of 600—1000℃ under N₂ atmosphere for the preparation of char. The evolution of microstructure of anthracite char was characterized by Raman spectroscopy. The de-NO_x reactivity of anthracite char was investigated using a thermogravimetric analyzer (TGA) under programmed temperature conditions. The present work is focused on the impact of pyrolysis temperature on anthracite char microstructure and de-NO_x reactivity. The char microstructure was affected significantly by heat treatment temperature. The difference between G and D1 band position and all Raman band areas were found to decrease with increasing pyrolysis temperature. In addition, band area ratio, I_D1/I_G and I_D3/I_G, were shown to initially increase and then decrease with the increase of pyrolysis temperature, while with which I_G/I_All varied oppositely. As a result, the Longping anthracite was subjected to carbonization and subsequent preliminary graphitization during pyrolysis. It was found that the de-NO_x reactivity of anthracite char decreased with increasing pyrolysis temperature, largely due to the reduction of active structure and the increase of structural order, also leading to the gradual increase of reaction activation energy.