化工学报 ›› 2022, Vol. 73 ›› Issue (6): 2732-2741.doi: 10.11949/0438-1157.20220110

• 能源和环境工程 • 上一篇    下一篇

ReaxFF MD模拟揭示的煤热解挥发分自由基反应的竞争与协调

郑默1,3(),李晓霞1,2,3   

  1. 1.中国科学院过程工程研究所多相复杂系统国家重点实验室，北京 100190
    2.中国科学院大学化学工程学院，北京 100049
    3.中国科学院绿色过程制造创新研究院，北京 100190
  • 收稿日期:2022-01-19 修回日期:2022-02-23 出版日期:2022-06-05 发布日期:2022-06-30
  • 通讯作者: 郑默 E-mail:mzheng@ipe.ac.cn
  • 作者简介:郑默（1988—），女，博士，副研究员，mzheng@ipe.ac.cn
  • 基金资助:
    国家自然科学基金重大计划项目(91434105);多相复杂系统国家重点实验室自主基金项目(MPCS-2021-A-08);煤转化国家重点实验室开放课题基金项目(J21-22-301)

Revealing reaction compromise in competition for volatile radicals during coal pryolysis via ReaxFF MD simulation

Mo ZHENG1,3(),Xiaoxia LI1,2,3   

  1. 1.State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
    2.School of Chemical Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
    3.Innovation Academy for Green Manufacture, Chinese Academy of Sciences, Beijing 100190, China
  • Received:2022-01-19 Revised:2022-02-23 Published:2022-06-05 Online:2022-06-30
  • Contact: Mo ZHENG E-mail:mzheng@ipe.ac.cn

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摘要：

挥发分自由基的行为对调控煤热解焦油产物十分重要，但实验方法直接获得其化学反应存在困难。利用化学反应分子动力学 ReaxFF MD 模拟方法，结合基于GPU高性能计算和化学信息学分析，研究了煤基体中挥发分自由基（基本单元）及其涉及的分子群（系统）在热解过程中的演化规律，着重考察了挥发分自由基参与的被稳定反应和缩聚反应在煤热解过程中的竞争协调关系。大规模ReaxFF MD模拟结果表明，随温度升高，煤热解过程可分成三个区域：被稳定反应占主导的区域、被稳定和缩聚反应竞争区域和缩聚反应占主导的区域。其中被稳定反应占主导的区域主要发生在较低温或反应前期，使得焦油收率升高；缩聚反应占主导的区域出现在高温阶段或反应后期，使得煤热解结焦加剧。当热解体系处于从被稳定反应占主导到被稳定和缩聚反应竞争激烈的转折点时，焦油收率出现最大值；当处于从两类反应竞争激烈到缩聚反应占主导的转折点时，焦炭产物开始大量生成。煤热解中挥发分自由基参与的两类相互竞争的化学反应控制着煤热解过程中焦油收率的演化，可为调控焦油生成，以进一步获得高品质化学品提供理论指导。

关键词: 分子模拟, 化学反应, 介尺度, 煤热解, 挥发分自由基, 竞争协调

Abstract:

The behavior of volatile radicals is very important for regulating coal pyrolysis tar products, but it is difficult to obtain their chemical reactions directly by experimental methods. In this paper, two dominant mechanisms of stabilization of volatile radicals and condensation reactions in bituminous coal pyrolysis associated with volatile radicals were investigated by using the large-scale ReaxFF MD simulation combining with high-performance computing and cheminformatics based reaction analysis method. The number evolving trends for the competition of stabilization and condensation reactions with time under different temperature condition were obtained with the aid of the multilevel searching strategy. The results show that stabilization reactions of volatile radicals are dominant at relatively low temperature of primary pyrolysis stage while condensation reactions of volatile radicals dominate the late pyrolysis stage at high temperature. The compromise phenomenon in competition between stabilization and condensation reactions is observed when the temperature is a little higher than that of the stage transition from the primary pyrolysis to secondary pyrolysis. Importantly, the transition point from stabilization dominant stage to the intensive competition stage of stabilization and condensation corresponds to the highest yield of tar products, while the transition point from the intensive competition stage to condensation dominant stage corresponds to the starting point for char generation. The phenomenon indicates that such understanding of reaction competitions would be very helpful to modulate tar composition and obtain the high yield of tar products industrially.

Key words: molecular simulation, chemical reaction, mesoscale, coal pyrolysis, volatile radical, compromise in competition

中图分类号: 

  • TQ 530.2
1 刘振宇, 李清波. 煤化工在“碳中和”历程中不可或缺[N]. 中国科学报, 2021-08-23(3).
Liu Z Y, Li Q B. Coal chemical engineering is indispensable in the process of “carbon neutralization”[N]. China Science Daily, 2021-08-23(3).
2 Miura K. Mild conversion of coal for producing valuable chemicals[J]. Fuel Processing Technology, 2000, 62(2/3): 119-135.
3 Solomon P R, Serio M A, Suuberg E M. Coal pyrolysis: experiments, kinetic rates and mechanisms[J]. Progress in Energy and Combustion Science, 1992, 18(2): 133-220.
4 周国江, 刘竹涛, 战金辉, 等. 温度梯度与产物流动对先锋褐煤热解产物分布的影响[J]. 化工学报, 2018, 69(6): 2672-2680.
Zhou G J, Liu Z T, Zhan J H, et al. Effects of temperature gradient and product flow on distribution of pyrolysis products of Xianfeng lignite[J]. CIESC Journal, 2018, 69(6): 2672-2680.
5 刘振宇. 煤化学的前沿与挑战: 结构与反应[J]. 中国科学: 化学, 2014, 44(9): 1431-1439.
Liu Z Y. Advancement in coal chemistry: structure and reactivity[J]. Scientia Sinica Chimica, 2014, 44(9): 1431-1439.
6 Solomon P R, Fletcher T H, Pugmire R J. Progress in coal pyrolysis[J]. Fuel, 1993, 72(5): 587-597.
7 He W J, Liu Z Y, Liu Q Y, et al. Behaviors of radical fragments in tar generated from pyrolysis of 4 coals[J]. Fuel, 2014, 134: 375-380.
8 He W J, Liu Z Y, Liu Q Y, et al. Behavior of radicals during solvent extraction of three low rank bituminous coals[J]. Fuel Processing Technology, 2017, 156: 221-227.
9 Shi L, Liu Q Y, Guo X J, et al. Pyrolysis of coal in TGA: extent of volatile condensation in crucible[J]. Fuel Processing Technology, 2014, 121: 91-95.
10 Zhou Q Q, Liu Q Y, Shi L, et al. Behaviors of coking and radicals during reaction of volatiles generated from fixed-bed pyrolysis of a lignite and a subbituminous coal[J]. Fuel Processing Technology, 2017, 161: 304-310.
11 Li J H, Ge W, Wang W, et al. Focusing on mesoscales: from the energy-minimization multiscale model to mesoscience[J]. Current Opinion in Chemical Engineering, 2016, 13: 10-23.
12 Wang J W, Zhao B D, Li J H. Toward a mesoscale-structure-based kinetic theory for heterogeneous gas-solid flow: particle velocity distribution function[J]. AIChE Journal, 2016, 62(8): 2649-2657.
13 Mathews J P, van Duin A C T, Chaffee A L. The utility of coal molecular models[J]. Fuel Processing Technology, 2011, 92(4): 718-728.
14 Mathews J P, Chaffee A L. The molecular representations of coal — a review[J]. Fuel, 2012, 96: 1-14.
15 van Duin A C T, Dasgupta S, Lorant F, et al. ReaxFF: a reactive force field for hydrocarbons[J]. The Journal of Physical Chemistry A, 2001, 105(41): 9396-9409.
16 Senftle T P, Hong S, Islam M M, et al. The ReaxFF reactive force-field: development, applications and future directions[J]. Npj Computational Materials, 2016, 2: 15011.
17 Castro-Marcano F, Russo M F, van Duin A C T, et al. Pyrolysis of a large-scale molecular model for Illinois No.6 coal using the ReaxFF reactive force field[J]. Journal of Analytical and Applied Pyrolysis, 2014, 109: 79-89.
18 冯炜, 高红凤, 王贵, 等. 枣泉煤分子模型构建及热解的分子模拟[J]. 化工学报, 2019, 70(4): 1522-1531.
Feng W, Gao H F, Wang G, et al. Molecular model and pyrolysis simulation of Zaoquan coal[J]. CIESC Journal, 2019, 70(4): 1522-1531.
19 Salmon E, van Duin A C T, Lorant F, et al. Early maturation processes in coal(Ⅱ): Reactive dynamics simulations using the ReaxFF reactive force field on Morwell brown coal structures[J]. Organic Geochemistry, 2009, 40(12): 1195-1209.
20 Bhoi S, Banerjee T, Mohanty K. Molecular dynamic simulation of spontaneous combustion and pyrolysis of brown coal using ReaxFF[J]. Fuel, 2014, 136: 326-333.
21 Hong D K, Cao Z, Guo X. Effect of calcium on the secondary reactions of tar from Zhundong coal pyrolysis: a molecular dynamics simulation using ReaxFF[J]. Journal of Analytical and Applied Pyrolysis, 2019, 137: 246-252.
22 Gao M J, Li X X, Guo X, et al. Dynamic migration mechanism of organic oxygen in Fugu coal pyrolysis by large-scale ReaxFF molecular dynamics[J]. Journal of Analytical and Applied Pyrolysis, 2021, 156: 105109.
23 Salmon E, van Duin A C T, Lorant F, et al. Thermal decomposition process in algaenan of Botryococcus braunii race L(Ⅱ): Molecular dynamics simulations using the ReaxFF reactive force field[J]. Organic Geochemistry, 2009, 40(3): 416-427.
24 Castro-Marcano F, Kamat A M, Russo M F, et al. Combustion of an Illinois No. 6 coal char simulated using an atomistic char representation and the ReaxFF reactive force field[J]. Combustion and Flame, 2012, 159(3): 1272-1285.
25 Zheng M, Li X X, Guo L. Algorithms of GPU-enabled reactive force field (ReaxFF) molecular dynamics[J]. Journal of Molecular Graphics and Modelling, 2013, 41: 1-11.
26 Zheng M, Li X X, Wang M J, et al. Dynamic profiles of tar products during Naomaohu coal pyrolysis revealed by large-scale reactive molecular dynamic simulation[J]. Fuel, 2019, 253: 910-920.
27 Liu J, Li X X, Guo L, et al. Reaction analysis and visualization of ReaxFF molecular dynamics simulations[J]. Journal of Molecular Graphics and Modelling, 2014, 53: 13-22.
28 Zheng M, Li X X, Liu J, et al. Pyrolysis of Liulin coal simulated by GPU-based ReaxFF MD with cheminformatics analysis[J]. Energy & Fuels, 2014, 28(1): 522-534.
29 Gao M J, Li X X, Guo L. Pyrolysis simulations of Fugu coal by large-scale ReaxFF molecular dynamics[J]. Fuel Processing Technology, 2018, 178: 197-205.
30 Gao M J, Li X X, Ren C X, et al. Construction of a multicomponent molecular model of Fugu coal for ReaxFF-MD pyrolysis simulation[J]. Energy & Fuels, 2019, 33(4): 2848-2858.
31 Zheng M, Pan Y, Wang Z, et al. Capturing the dynamic profiles of products in Hailaer brown coal pyrolysis with reactive molecular simulations and experiments[J]. Fuel, 2020, 268: 117290.
32 Li X X, Zheng M, Ren C X, et al. ReaxFF molecular dynamics simulations of thermal reactivity of various fuels in pyrolysis and combustion[J]. Energy & Fuels, 2021, 35(15): 11707-11739.
33 Zheng M, Li X X, Nie F G, et al. Investigation of model scale effects on coal pyrolysis using ReaxFF MD simulation[J]. Molecular Simulation, 2017, 43(13/14/15/16): 1081-1088.
34 Zheng M, Li X X, Nie F G, et al. Investigation of overall pyrolysis stages for Liulin bituminous coal by large-scale ReaxFF molecular dynamics[J]. Energy & Fuels, 2017, 31(4): 3675-3683.
35 Zhang T T, Li X X, Qiao X J, et al. Initial mechanisms for an overall behavior of lignin pyrolysis through large-scale ReaxFF molecular dynamics simulations[J]. Energy & Fuels, 2016, 30(4): 3140-3150.
36 Zhang T T, Li X X, Guo L. Initial reactivity of linkages and monomer rings in lignin pyrolysis revealed by ReaxFF molecular dynamics[J]. Langmuir: the ACS Journal of Surfaces and Colloids, 2017, 33(42): 11646-11657.
37 Zheng M, Wang Z, Li X X, et al. Initial reaction mechanisms of cellulose pyrolysis revealed by ReaxFF molecular dynamics[J]. Fuel, 2016, 177: 130-141.
38 Mueller J E, van Duin A C T, W A Ⅲ Goddard. Application of the ReaxFF reactive force field to reactive dynamics of hydrocarbon chemisorption and decomposition[J]. The Journal of Physical Chemistry C, 2010, 114(12): 5675-5685.
39 韩君易, 李晓霞, 郭力, 等. ReaxFF MD模拟的物种和化学反应自动分类及可视化[J]. 计算机与应用化学, 2015, 32(5): 519-526.
Han J Y, Li X X, Guo L, et al. Automatic classification and visualization of species and reactions obtained from ReaxFF MD simulations[J]. Computers and Applied Chemistry, 2015, 32(5): 519-526.
40 贺巧鑫, 任春醒, 李晓霞, 等. ReaxFF MD模拟结果分析中化学反应路径网络的发现[J]. 计算机与应用化学, 2019, 36(4): 299-303.
He Q X, Ren C X, Li X X, et al. Discovery of chemical reaction networks in analysis of ReaxFF MD simulations[J]. Computers and Applied Chemistry, 2019, 36(4): 299-303.
41 唐钰杰, 郑默, 任春醒, 等. ReaxFF MD局部区域反应追踪与物理性质可视化分析[J]. 物理化学学报, 2021, 37(10): 77-87.
Tang Y J, Zheng M, Ren C X, et al. Visualized reaction tracking and physical property analysis for a picked 3D area in a reactive molecular dynamics simulation system[J]. Acta Physico-Chimica Sinica, 2021, 37(10): 77-87.
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