摘要
To deepen understanding of the evolution of coal char microstructural properties of coal char during the co-pyrolysis of coking coal with additives,this study incorporated two typical additives,coal tar pitch(CTP)and waste plastic(HDPE),into a blended coal sample and carried out pyrolysis experiments.The pyrolysis process and the microstructure of char were systematically characterized using various analytical techniques,including thermogravimetric analysis(TGA),X-ray diffraction(XRD)and Raman spectroscopy.Data correlation analysis was performed to reveal the mechanism of carbon structural ordering evolution within the critical temperature range(350−600℃)from colloidal layer formation to semi-coke conversion in coking coal,and to elucidate the regulatory effects of different additives on coal pyrolysis pathways.The results indicate that HDPE releases free radicals during high-temperature pyrolysis,accelerating the pyrolysis reaction and increase the yield of volatile components.Conversely,CTP facilitates pyrolysis at low temperatures through its light components,thereby delaying high-temperature reactions due to the colloidal layer’s effect.XRD results indicate that during the process of pyrolysis,there is a progressive decrease in the interlayer spacing of aromatic layers(d002),while the aromatic ring stacking height(L_(c))and lateral size(L_(a))undergo significant of carbon skeleton ordering.Further comparative reveals that CTP partially suppresses structural ordering at low temperatures,whereas HDPE promotes the condensation and alignment of aromatic clusters via a free radical mechanism.Raman spectroscopy reveals a two-stage reorganization mechanism in the microstructure of the coal char:the decrease in the I_(D)/I_(G)ratio between 350 and 550℃is primarily attributed to the cleavage of aliphatic side chains and cross-linking bonds,leading to a reduction in defective structures;whereas the increase in ID/IG between 550 and 600℃is closely associated with enhanced condensation reactions of aromatic structures.Correlation analysis further demonstrates progressive graphitization during pyrolysis,with a significant positive correlation(R^(2)>0.85)observed between d002 and the full width at half maximum of the G-band(FWHM-G).
本研究在混合煤样中分别引入两种典型添加剂—煤沥青(CTP)和废塑料(HDPE)并进行热解实验。采用热重分析(TGA)、X射线衍射(XRD)和拉曼光谱(Raman)等分析手段,对热解过程及所得煤焦的微观结构进行表征,并通过数据关联分析,旨在揭示炼焦煤在胶质体形成至半焦转化关键温度区间(350–600℃)内炭结构有序化演变机制,阐明不同添加剂对煤热解路径的调控作用。结果表明,HDPE在高温裂解释放自由基,加速热解反应并提高挥发分产率;CTP则通过轻质组分在低温促进热解,并因胶质层作用延缓高温反应。XRD结果表明,热解过程中芳香层片间距(d002)逐渐减小,芳环堆叠高度(L_(c))与横向尺寸(L_(a))显著增加,表明炭骨架有序化程度不断提升。进一步对比表明,CTP在低温阶段一定程度抑制结构有序化,而HDPE通过自由基机制芳香簇的缩合与排列。Raman分析揭示了两阶段煤焦微观结构重组特征:在350–550℃,ID/IG值的下降主要归因于脂肪侧链和交联键的断裂,导致缺陷结构减少;而在550–600℃,ID/IG值的上升则与芳香结构的缩聚反应密切相关。关联分析结果表明,热解过程中样品石墨化程度增加,d002与FWHM-G呈显著正相关(R^(2)>0.85)。
出处
《燃料化学学报(中英文)》
北大核心
2026年第2期153-165,共13页
Journal of Fuel Chemistry and Technology
基金
Supported by National Natural Science Foundation of China(22378180,22078141)
Education Department Foundation of Liaoning Province(JYTMS20230960)。
