化工学报 ›› 2022, Vol. 73 ›› Issue (7): 2844-2857.doi: 10.11949/0438-1157.20220278

• 热力学 • 上一篇    下一篇

基于分子反应动力学模拟的六甲基二硅氧烷热解机理研究

陈玉弓(),陈昊,黄耀松()   

  1. 苏州大学能源学院,江苏 苏州 215006
  • 收稿日期:2022-03-01 修回日期:2022-05-09 出版日期:2022-07-05 发布日期:2022-08-01
  • 通讯作者: 黄耀松 E-mail:ygchen@stu.suda.edu.cn;yshuang@suda.edu.cn
  • 作者简介:陈玉弓(1997—),男,硕士研究生,ygchen@stu.suda.edu.cn
  • 基金资助:
    国家自然科学基金项目(52006153)

Study on pyrolysis mechanism of hexamethyldisiloxane using reactive molecular dynamics simulations

Yugong CHEN(),Hao CHEN,Yaosong HUANG()   

  1. College of Energy, Soochow University, Suzhou 215006, Jiangsu, China
  • Received:2022-03-01 Revised:2022-05-09 Published:2022-07-05 Online:2022-08-01
  • Contact: Yaosong HUANG E-mail:ygchen@stu.suda.edu.cn;yshuang@suda.edu.cn

摘要:

六甲基二硅氧烷是燃烧合成高纯二氧化硅纳米颗粒的重要前体,采用ReaxFF分子动力学模拟方法研究其高温热解过程,讨论了三种不同反应力场对模拟的影响并分析其可靠性,选择其中最合适的力场开展不同温度与压力下的热解产物分析,结合气相色谱实验,揭示六甲基二硅氧烷的热解路径和机理。结果表明,反应力场对ReaxFF分子动力学模拟有重要影响,通过比较分析获得了最佳反应力场,六甲基二硅氧烷的初始热解反应为Si—C键断裂导致的CH3脱离,温度升高会加剧解热反应的发生且使产物趋向于碎片化,热解的主要产物为CH3、CH4、C2烃、H2、CH2O等小分子以及SiH4、SiH2、CH4Si等含硅化合物。压力的改变会造成热解体系浓度的改变,从而影响分子间相互碰撞概率和反应的发生,压力越大则越容易形成稳定的热解产物。

关键词: 六甲基二硅氧烷, 热解, 反应力场, 反应动力学模拟, 气相色谱

Abstract:

Hexamethyldisiloxane (HMDSO) is an important precursor for the combustion synthesis of high-purity silica nanoparticles. The pyrolysis of hexamethyldisiloxane was investigated in this work by using ReaxFF reactive molecular dynamics simulations. The effects of three different reaction force fields on the simulations are evaluated and the reliability of each force field is analyzed. The most suitable force field was selected to investigate the pyrolysis products at different temperatures and pressures. The simulation results were used to reveal the pyrolysis path and mechanism of hexamethyldisiloxane together with the gas chromatography experiments. The results show that the reaction force field has important influences on the results of ReaxFF molecular dynamics simulations and the optimal reaction force field is obtained through the comparative analysis. The initial reaction step for HMDSO pyrolysis is the removal of CH3 radical induced by Si—C bond breaking. Temperature is a major factor affecting the pyrolysis of HMDSO. The total molecular number of pyrolysis products increases with the temperature increasing and the products tended to be fragmented. The small hydrocarbon molecules (i.e., CH3, CH4, C2 hydrocarbons, H2, CH2O, etc.) and Si-containing products (i.e., SiH4, SiH2, CH4Si, etc.) appear in the middle and last stages of the pyrolysis process. The change of pressure will cause the change of the concentration of the pyrolysis system, thus affecting the probability of intermolecular collision and the occurrence of the reaction. The higher the pressure, the easier it is to form a stable pyrolysis product.

Key words: hexamethyldisiloxane, pyrolysis, reactive force field, reactive molecular dynamics simulations, gas chromatography

中图分类号: 

  • O 643.12

图1

HMDSO分子几何构型"

图2

HMDSO分子热解模拟体系的初始构型"

图3

不同目标温度下模拟初始阶段的温度演化"

图4

不同力场在升温模拟过程中体系HMDSO分子数随时间的变化"

图5

模拟时间为40 ps时力场A (a)、力场B (b)及力场C (c)的体系分子分布"

图6

HMDSO单分子的初始热解反应步"

图7

不同力场条件下主要产物随时间的变化"

图8

不同力场条件下HMDSO模拟结束时体系分子分布"

图9

不同温度下部分主要产物随时间的变化"

图10

不同温度下主要含Si产物随时间的变化"

图11

1800 K与2500 K温度条件模拟体系展示"

图12

不同压力下模拟体系总分子数随时间的变化"

图13

不同压力下模拟体系势能随时间的变化"

图14

不同压力下部分主要产物随时间的变化"

图15

不同压力下主要含Si产物随时间的变化"

图16

不同压力条件下模拟体系分子分布"

表1

气相色谱仪预设化合物名及结构"

Peak entryChemical nameChemical structurePeak entryChemical nameChemical structure
1methane2ethane
3ethylene4propane
5cyclopropane6propylene
7iso-butane8n-butane
91,2-propadiene101-butene
11trans-2-butene122-methylpropene
13iso-pentane14cis-2-butene
15n-pentane161,3-butadiene

图17

温度为700℃、800℃、900℃时HMDSO热解色谱图"

表2

不同温度下ReaxFF MD模拟部分主要烃类产物占总产物分子数的比例"

Chemical namePercentage/%
1600 K1800 K2000 K2500 K
methane3.7049.2148.1919.83
acetylene03.1712.0510.34
ethylene3.707.946.028.62
ethane3.7001.200.86

图18

HMDSO主要热解反应路径"

1 Flikkema E, Bromley S T. A new interatomic potential for nanoscale silica[J]. Chemical Physics Letters, 2003, 378(5/6): 622-629.
2 Kammler H K, Pratsinis S E. Scaling-up the production of nanosized SiO2-particles in a double diffusion flame aerosol reactor[J]. Journal of Nanoparticle Research, 1999, 1(4): 467-477.
3 Sadasivan S, Rasmussen D H, Chen F P, et al. Preparation and characterization of ultrafine silica[J]. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 1998, 132(1): 45-52.
4 Feroughi O M, Deng L, Kluge S, et al. Experimental and numerical study of a HMDSO-seeded premixed laminar low-pressure flame for SiO2 nanoparticle synthesis[J]. Proceedings of the Combustion Institute, 2017, 36(1): 1045-1053.
5 Yue R L, Meng D, Ni Y, et al. One-step flame synthesis of hydrophobic silica nanoparticles[J]. Powder Technology, 2013, 235: 909-913.
6 Chernyshev E A, Krasnova T L, Sergeev A P, et al. Siloxanes as sources of silanones[J]. Russian Chemical Bulletin, 1997, 46(9): 1586-1589.
7 Alexander M R, Jones F R, Short R D. Mass spectral investigation of the radio-frequency plasma deposition of hexamethyldisiloxane[J]. The Journal of Physical Chemistry B, 1997, 101(18): 3614-3619.
8 Chrystie R S M, Janbazi H, Dreier T, et al. Comparative study of flame-based SiO2 nanoparticle synthesis from TMS and HMDSO: SiO-LIF concentration measurement and detailed simulation[J]. Proceedings of the Combustion Institute, 2019, 37(1): 1221-1229.
9 Almond M J, Becerra R, Bowes S J, et al. A mechanistic study of the low pressure pyrolysis of linear siloxanes[J]. Physical Chemistry Chemical Physics: PCCP, 2009, 11(40): 9259-9267.
10 McArdle S, Endo S, Aspuru-Guzik A, et al. Quantum computational chemistry[J]. Reviews of Modern Physics, 2020, 92: 015003.
11 Dohm S, Bursch M, Hansen A, et al. Semiautomated transition state localization for organometallic complexes with semiempirical quantum chemical methods[J]. Journal of Chemical Theory and Computation, 2020, 16(3): 2002-2012.
12 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.
13 Chenoweth K, van Duin A C T, Goddard W A. ReaxFF reactive force field for molecular dynamics simulations of hydrocarbon oxidation[J]. The Journal of Physical Chemistry. A, 2008, 112(5): 1040-1053.
14 Bhoi S, Banerjee T, Mohanty K. Insights on the combustion and pyrolysis behavior of three different ranks of coals using reactive molecular dynamics simulation[J]. RSC Advances, 2016, 6(4): 2559-2570.
15 Arvelos S, Abrahão O, Eponina Hori C. ReaxFF molecular dynamics study on the pyrolysis process of cyclohexanone[J]. Journal of Analytical and Applied Pyrolysis, 2019, 141: 104620.
16 Xu F, Liu H, Wang Q, et al. ReaxFF-based molecular dynamics simulation of the initial pyrolysis mechanism of lignite[J]. Fuel Processing Technology, 2019, 195: 106147.
17 Liu Q, Liu S X, Lv Y D, et al. Atomic-scale insight into the pyrolysis of polycarbonate by ReaxFF-based reactive molecular dynamics simulation[J]. Fuel, 2021, 287: 119484.
18 Wang Q D, Wang J B, Li J Q, et al. Reactive molecular dynamics simulation and chemical kinetic modeling of pyrolysis and combustion of n-dodecane[J]. Combustion and Flame, 2011, 158(2): 217-226.
19 Chen B, Wei X Y, Yang Z S, et al. ReaxFF reactive force field for molecular dynamics simulations of lignite depolymerization in supercritical methanol with lignite-related model compounds[J]. Energy & Fuels, 2012, 26(2): 984-989.
20 Chen B, Diao Z J, Zhao Y L, et al. A ReaxFF molecular dynamics (MD) simulation for the hydrogenation reaction with coal related model compounds[J]. Fuel, 2015, 154: 114-122.
21 van Duin A C T, Strachan A, Stewman S, et al. ReaxFFSiO reactive force field for silicon and silicon oxide systems[J]. The Journal of Physical Chemistry A, 2003, 107(19): 3803-3811.
22 Liu L C, Liu Y, Zybin S V, et al. ReaxFF-lg: correction of the ReaxFF reactive force field for London dispersion, with applications to the equations of state for energetic materials[J]. The Journal of Physical Chemistry A, 2011, 115(40): 11016-11022.
23 Liu J, Guo X. ReaxFF molecular dynamics simulation of pyrolysis and combustion of pyridine[J]. Fuel Processing Technology, 2017, 161: 107-115.
24 Chenoweth K, Cheung S, van Duin A C T, et al. Simulations on the thermal decomposition of a poly(dimethylsiloxane) polymer using the ReaxFF reactive force field[J]. Journal of the American Chemical Society, 2005, 127(19): 7192-7202.
25 Iype E, Hütter M, Jansen A P J, et al. Parameterization of a reactive force field using a Monte Carlo algorithm[J]. Journal of Computational Chemistry, 2013, 34(13): 1143-1154.
26 Wood M A, van Duin A C T, Strachan A. Coupled thermal and electromagnetic induced decomposition in the molecular explosive αHMX; a reactive molecular dynamics study[J]. The Journal of Physical Chemistry A, 2014, 118(5): 885-895.
27 Chenoweth K, van Duin A C T, Persson P, et al. Development and application of a ReaxFF reactive force field for oxidative dehydrogenation on vanadium oxide catalysts[J]. The Journal of Physical Chemistry A, 2008, 112(37): 8886.
28 Srinivasan S G, van Duin A C T, Ganesh P. Development of a ReaxFF potential for carbon condensed phases and its application to the thermal fragmentation of a large fullerene[J]. The Journal of Physical Chemistry A, 2015, 119(4): 571-580.
29 Newsome D A, Sengupta D, Foroutan H, et al. Oxidation of silicon carbide by O2 and H2O: a ReaxFF reactive molecular dynamics study (part I)[J]. The Journal of Physical Chemistry C, 2012, 116(30): 16111-16121.
30 Kulkarni A D, Truhlar D G, Goverapet S S, et al. Oxygen interactions with silica surfaces: coupled cluster and density functional investigation and the development of a new ReaxFF potential[J]. The Journal of Physical Chemistry C, 2013, 117(1): 258-269.
31 Soria F, Zhang W W, Paredes-Olivera P A, et al. Si/C/H ReaxFF reactive potential for silicon surfaces grafted with organic molecules[J]. The Journal of Physical Chemistry C, 2018, 122(41): 23515-23527.
32 Zhang L Z, Zybin S V, van Duin A C T, et al. Carbon cluster formation during thermal decomposition of octahydro-1, 3, 5, 7-tetranitro-1, 3, 5, 7-tetrazocine and 1, 3, 5-triamino-2, 4, 6-trinitrobenzene high explosives from ReaxFF reactive molecular dynamics simulations[J]. The Journal of Physical Chemistry A, 2009, 113(40): 10619-10640.
[1] 陈永安, 周安宁, 李云龙, 石智伟, 贺新福, 焦卫红. 磁性MgFe2O4及其核壳催化剂制备与煤热解性能研究[J]. 化工学报, 2022, 73(7): 3026-3037.
[2] 郑默, 李晓霞. ReaxFF MD模拟揭示的煤热解挥发分自由基反应的竞争与协调[J]. 化工学报, 2022, 73(6): 2732-2741.
[3] 陈冠益, 童图军, 李瑞, 王燕杉, 颜蓓蓓, 李宁, 侯立安. 热解时间对污泥生物炭活化过硫酸盐的影响研究[J]. 化工学报, 2022, 73(5): 2111-2119.
[4] 赵希强, 张健, 孙爽, 王文龙, 毛岩鹏, 孙静, 刘景龙, 宋占龙. 生物质炭改性微球去除化工废水中无机磷的性能研究[J]. 化工学报, 2022, 73(5): 2158-2173.
[5] 郭行, 韩纹莉, 董晓玲, 李文翠. 调控炭化过程优化煤基硬炭负极储钠性能[J]. 化工学报, 2022, 73(4): 1794-1806.
[6] 欧阳志鹏, 刘庭峰, 冷尔唯, 冯天毅, 曾建辉, 龚勋. 纤维素低氧环境下热解特性和糖类生成机制[J]. 化工学报, 2022, 73(3): 1351-1358.
[7] 李勇, 闫伦靖, 李晓荣, 靳鑫, 李挺, 刘倩, 王美君, 孔娇, 常丽萍, 鲍卫仁. 酸/碱催化剂对低阶煤热解挥发分转化行为的作用机制研究[J]. 化工学报, 2022, 73(3): 1173-1183.
[8] 徐飞翔, 蒋丽群, 郑安庆, 赵增立. 碳基固体酸催化纤维素热解制备左旋葡聚糖和左旋葡萄糖酮[J]. 化工学报, 2022, 73(3): 1166-1172.
[9] 黄明, 朱亮, 丁紫霞, 毛一婷, 马中青. 生物质三组分与低密度聚乙烯共催化热解制取轻质芳烃的协同作用机理[J]. 化工学报, 2022, 73(2): 699-711.
[10] 罗紫藤, 周秋成, 王雨露, 席引尚, 周安宁, 陈福欣. 基于Py-GC/MS研究热解反应中自由基的捕获反应[J]. 化工学报, 2022, 73(2): 914-922.
[11] 杨英杰, 杨赫, 朱家龙, 郭双淇, 尚妍, 李扬, 靳立军, 胡浩权. 淖毛湖煤慢速热解过程官能团相互作用[J]. 化工学报, 2022, 73(2): 865-875.
[12] 张照曦,钟梅,李建,亚力昆江?吐尔逊. 改性蒙脱土对新疆和丰煤热解行为的影响[J]. 化工学报, 2022, 73(1): 402-410.
[13] 王冠宇, 朱玲君, 周劲松, 王树荣. 基于组分协同效应的造纸厂固体废弃物热解特性研究[J]. 化工学报, 2022, 73(1): 393-401.
[14] 全翠, 张广涛, 许毓, 高宁博. 污泥热解残渣中重金属形态分布的研究进展[J]. 化工学报, 2022, 73(1): 134-143.
[15] 戴晓业, 安青松, 许云婷, 史琳. 废弃制冷剂降解方法研究现状及思考[J]. 化工学报, 2021, 72(S1): 1-6.
Viewed
Full text


Abstract

Cited

  Shared   
  Discussed   
No Suggested Reading articles found!