摘要
【目的】富油煤结构复杂,热解反应过程与机理不明晰,需要进一步研究富油煤结构与其热解产物分布的构效关系,明晰富油煤热解提油机理。【方法】以陕北典型富油煤为研究对象,结合^(13)C NMR、FTIR和XPS等表征方法,计算并构建富油煤分子模型,分子式为C_(444)H_(380)O_(74)N_(8)S。基于构建的富油煤分子模型,通过ReaxFF MD对陕北富油热解产物分布、热解特性以及焦油生成机理进行了深入分析。【结果和讨论】结果表明,陕北富油煤具有大量脂肪侧链和桥键等富氢结构,受热容易分解生成焦油和气体等挥发分。温度和升温速率对富油煤热解产物分布影响显著,模拟热解温度在1500 K时富油煤没有完全反应,挥发性产物质量分数为7.8%;模拟热解温度升高至2000~3000 K时,分子及自由基碎片运动越剧烈,二次反应也更明显。随着升温速率的增加,气体产物降低,而焦油产物先增加后减少;升温速率在100~200 K/ps时,富油煤没有完全热解,导致挥发分产率低于36%。根据热解产物分布推测,陕北富油煤热解反应机理是富油煤大分子中富氢结构受热断裂形成自由基碎片,进一步发生热解生成轻质焦油、重质焦油和气体产物。
[Objective]The pyrolysis process and mechanism of tar-rich coals remain unclear due to their complex structures.Therefore,it is necessary to investigate the structure-activity relationship between their structure and the distributions of their pyrolytic products and determine the mechanism behind their pyrolysis for tar extraction.[Methods]Focusing on typical tar-rich coals from northern Shaanxi Province,this study calculated and constructed the molecular model of the coals using characterization methods such as carbon-13 nuclear magnetic resonance(^(13)C NMR),Fourier transform infrared spectroscopy(FTIR),and X-ray photoelectron spectroscopy(XPS),determining the molecular formula at C_(444)H_(380)O_(74)N_(8)S.Based on the molecular model,this study examined the pyrolytic product distributions,pyrolysis characteristics,and tar production mechanism of the tar-rich coals using the reactive force field molecular dynamics(ReaxFF MD).[Results and Conclusions]The results reveal that the tar-rich coals from northern Shaanxi Province exhibit substantial hydrogen-rich structures,such as aliphatic side chains and bridge bonds,tending to decompose into volatile constituents like tar and gas when heated.The product distributions during the pyrolysis of tar-rich coals are significantly influenced by the temperature and heating rate.At a simulated pyrolysis temperature of 1500 K,the tar-rich coals underwent partial reactions,yielding volatile constituents with a mass fraction of 7.8%.As the simulated pyrolysis temperature rose to 2000 to 3000 K,molecular and radical fragments moved more intensely,accompanied by more pronounced secondary reactions.With an increase in the heating rate,gas products decreased,whereas tar products increased first and then decreased.At heating rates between 100 and 200 K/ps,the tar-rich coals were partially pyrolyzed,leading to mass fractions of volatile constituents below 36%.As inferred from the distributions of pyrolytic products,the mechanism behind the pyrolysis of tar-rich coals from northern Shaanxi Province is that the hydrogen-rich structures in tar-rich coal macromolecules break under heating,forming radical fragments,which are further pyrolyzed to produce light tar,heavy tar,and gas.
作者
郭伟
杨盼曦
俞尊义
杨甫
王晶
马丽
李红强
杨伯伦
吴志强
GUO Wei;YANG Panxi;YU Zunyi;YANG Fu;WANG Jing;MA Li;LI Hongqiang;YANG Bolun;WU Zhiqiang(School of Chemical Engineering and Technology,Xi’an Jiaotong University,Xi’an 710049,China;Shaanxi Province Energy and Chemical Process Strengthening Key Laboratory,Xi’an 710049,China;Key Laboratory of Coal Resources Exploration and Comprehensive Utilization,Ministry of Natural and Resources,Xi’an 710021,China;Shaanxi Coal Geology Group Co.,Ltd.,Xi’an 710021,China;School of Electrical Engineering,Xi’an Jiaotong University,Xi’an 710049,China)
出处
《煤田地质与勘探》
EI
CAS
CSCD
北大核心
2024年第7期132-143,共12页
Coal Geology & Exploration
基金
自然资源部煤炭资源勘查与综合利用重点实验室开放基金项目(SMDZ-2023-Z020)
陕西省创新能力支持计划项目(2023-KJXX-004,2022KXJ-126)。
关键词
富油煤
煤热解
分子模拟
热解温度
升温速率
模型构建
富氢结构
tar-rich coal
coal pyrolysis
molecular simulation
pyrolysis temperature
heating rate
model construction
hydrogen-rich structure
