首页|陕北富油煤分子模型构建及其热解提油分子动力学特性

陕北富油煤分子模型构建及其热解提油分子动力学特性

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[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13C 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C444H380O74N8S.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 1 500 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 2 000~3 000 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.
Molecular modeling of tar-rich coals from northern Shaanxi and their molecular dynamic characteristics in the process of pyrolysis for tar extraction
[Objective]The pyrolysis process and mechanism of tar-rich coals remain unclear due to their complex struc-tures.Therefore,it is necessary to investigate the structure-activity relationship between their structure and the distribu-tions of their pyrolytic products and determine the mechanism behind their pyrolysis for tar extraction.[Methods]Fo-cusing 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(13C NMR),Fourier transform infrared spectroscopy(FTIR),and X-ray photoelectron spectroscopy(XPS),determining the molecular for-mula at C444H380O74N8S.Based on the molecular model,this study examined the pyrolytic product distributions,pyrolys-is 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 ex-hibit 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 sig-nificantly influenced by the temperature and heating rate.At a simulated pyrolysis temperature of 1 500 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 2 000 to 3 000 K,molecular and radical fragments moved more intensely,accompanied by more pro-nounced secondary reactions.With an increase in the heating rate,gas products decreased,whereas tar products in-creased 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.

tar-rich coalcoal pyrolysismolecular simulationpyrolysis temperatureheating ratemodel constructionhydrogen-rich structure

郭伟、杨盼曦、俞尊义、杨甫、王晶、马丽、李红强、杨伯伦、吴志强

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西安交通大学 化学工程与技术学院,陕西 西安 710049

陕西省能源化工过程强化重点实验室,陕西 西安 710049

自然资源部煤炭资源勘查与综合利用重点实验室,陕西 西安 710021

陕西省煤田地质集团有限公司,陕西 西安 710021

西安交通大学 电气工程学院,陕西 西安 710049

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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

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陕西省创新能力支持计划项目陕西省创新能力支持计划项目

SMDZ-2023-Z0202023-KJXX-0042022KXJ-126

2024

煤田地质与勘探
中煤科工集团西安研究院

煤田地质与勘探

CSTPCD北大核心
影响因子:1.079
ISSN:1001-1986
年,卷(期):2024.52(7)
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