淖毛湖煤加氢热解产物特性及半焦气化反应性

Products characteristics and char gasification reactivityof Naomaohu coal hydropyrolysis

在加压固定床反应器中进行淖毛湖煤在常压和1.5 MPa氢气和氮气中的热解试验,利用多种表征方法对比研究了氢气和氮气下的热解产物产率和组成及半焦结构的变化,并利用热重分析研究热解半焦的CO_(2)气化反应性。结果表明:与常压N_(2)中热解相比,煤在加压的H_(2)中热解可有效提高热解气体中CH_(4)和C_(2)~C_(3)的产率,在800℃热解CH_(4)和C_(2)~C_(3)的体积产率分别由53.5和16.6 mL/g增至345.6和20.8 mL/g。焦油和轻质焦油产率也有效提升,在600℃下,与常压N_(2)中热解相比,1.5 MPa H_(2)中煤热解的焦油产率由19.3%升至22.8%,焦油中脂肪烃含量由35.5%降至14.8%,单环芳烃含量由8.3%增至28.9%,轻质焦油质量分数和产率分别升至95.0%和21.8%。半焦的N_(2)吸附和拉曼光谱分析结果表明,煤在加压H 2中热解得到半焦的比表面积和孔体积由常压氮气下的40 m^(2)/g和0.05 cm^(3)/g增至289 m^(2)/g和0.16 cm^(3)/g,孔结构显著发展,有利于半焦的CO_(2)气化反应进行;而半焦的石墨化程度及大芳香环比例增加,不利于半焦气化反应;但由热重分析得到的加压加氢热解半焦的CO_(2)气化反应性明显提高,表明孔结构对半焦CO_(2)气化反应性起主要作用。

The pyrolysis experiments of Naomaohu coal(NMH)at atmospheric pressure and 1.5 MPa H_(2)and N_(2)were carried out in a pressurized fixed-bed reactor.The products yield and composition and char structure under H_(2)and N_(2)were comparatively investigated by various characterization methods.The CO_(2)gasification reactivity of char was studied by a thermogravimetric analyzer.The results indicate that pyrolysis of coal in pressurized H_(2)can effectively increase the yield of CH_(4)and C_(2)-C_(3),from 53.5 and 16.6 mL/g in atmospheric N_(2)to 345.6 and 20.8 mL/g in pressurized H_(2),respectively,during the coal pyrolysis at 800℃.Tar yield and quality is also effectively improved.Compared coal pyrolysis at 600℃under 1.5 MPa H_(2)with that under atmospheric pressure N_(2),the tar yield increases from 19.3%to 22.8%,the aliphatic hydrocarbon content decreases from 35.5%to 14.8%,the monocyclic aromatic hydrocarbon content increases from 8.3%to 28.9%,and the light tar content and yield increases to 95%and 21.8%,respectively.The results of N_(2)adsorption and Raman spectroscopy show that the specific surface area and pore volume of the char in pressurized hydropyrolysis increase from 40 m^(2)/g and 0.05 cm^(3)/g in atmospheric N_(2)to 289 m^(2)/g and 0.16 cm^(3)/g,and the pore structure is significantly developed.This is beneficial to the CO_(2)gasification reaction of char.The graphitization degree and the proportion of large aromatic ring increase,which is not conducive to the gasification reaction of char.The thermogravimetric analysis results show that the gasification reactivity of char from pressurized hydropyrolysis is significantly higher,which indicates that pore structure plays a main role in the influence on the CO_(2)gasification reactivity of the char.