化工学报 ›› 2023, Vol. 74 ›› Issue (7): 2935-2946.DOI: 10.11949/0438-1157.20230207

• 催化、动力学与反应器 • 上一篇    下一篇

基于分子动力学的焦炭溶损反应及其机理研究

陈吉1(), 洪泽3, 雷昭1,2(), 凌强1,2, 赵志刚1,2, 彭陈辉3, 崔平1,2()   

  1. 1.安徽工业大学冶金工程学院,安徽 马鞍山 243002
    2.煤清洁转化与高值化利用安徽省重点实验室,安徽 马鞍山 243032
    3.湖南涟源钢铁集团,湖南 娄底 417000
  • 收稿日期:2023-03-08 修回日期:2023-07-06 出版日期:2023-07-05 发布日期:2023-08-31
  • 通讯作者: 雷昭,崔平
  • 作者简介:陈吉(1993—),男,博士研究生,chenjiahut@126.com
  • 基金资助:
    国家自然科学基金项目(22278001)

Study on coke dissolution loss reaction and its mechanism based on molecular dynamics simulations

Ji CHEN1(), Ze HONG3, Zhao LEI1,2(), Qiang LING1,2, Zhigang ZHAO1,2, Chenhui PENG3, Ping CUI1,2()   

  1. 1.School of Metallurgical Engineering, Anhui University of Technology, Ma’anshan 243002, Anhui, China
    2.Anhui Province Key Laboratory of Coal Clean Conversion and High Valued Utilization, Ma’anshan 243032, Anhui, China
    3.Lianyuan Steel Group Corporation, Loudi 417000, Hunan, China
  • Received:2023-03-08 Revised:2023-07-06 Online:2023-07-05 Published:2023-08-31
  • Contact: Zhao LEI, Ping CUI

摘要:

为从分子层面研究焦炭溶损反应及其机理,借助分子动力学和第一性原理构建了一种包含石墨化碳和非石墨化碳的焦炭分子模型,研究了电荷密度和孔径大小对焦炭溶损反应及其机理的影响,并通过实验对模拟结果加以验证。结果表明,所建模型真密度在焦炭实测密度范围内;焦炭石墨化程度越高,碳原子周边电荷密度越小,其溶损反应程度越低,实验结果与模拟结果相近;CO2在孔径大于50 Å(1 Å=1×10-10 m)气孔内以扩散为主,其扩散表观活化能最小,为131.24 kJ/mol;在孔径小于2 Å气孔内以吸附为主,其吸附能的绝对值最大,为192.54 kJ/mol;焦炭溶损反应机理包括焦炭分子生成石墨化碳和非石墨化碳原子的裂解反应、碳原子之间的异构化反应以及碳原子与CO2的氧化反应,在氧化反应过程中,碳原子与CO2反应生成的烯酮式结构会因其稳定性差裂解成CO,完成反应过程。

关键词: 焦炭, 溶损反应, 机理, 分子模拟, 电荷密度, 孔径, 吸附

Abstract:

In order to study the coke dissolution loss reaction and its mechanism at the molecular level, a molecular model of coke containing graphitized carbon and non-graphitized carbon was constructed by molecular dynamics and first principles. The accuracy of the model was verified by comparing the true density of the molecular model. The influence of charge density and pore structure on the coke dissolution loss reaction was analyzed, and the mechanism of the reaction was also discussed. The results show that the true density of the model is within the range of the measured true density of coke. The higher the graphitization degree of coke, the smaller the charge density around carbon atoms, and the lower the degree of dissolution loss reaction. The experimental results are similar to the simulation results. CO2 is mainly diffused in pores above 50 Å, with the lowest diffusion activation energy (131.24 kJ /mol), while it is mainly adsorbed in pores below 2 Å, with the highest adsorption energy (-192.54 kJ/mol). The mechanism of coke dissolution loss reaction includes the cracking reaction of graphitized carbon and non-graphitized carbon atoms, the isomerization reaction between two kinds of carbon atoms and the oxidation reaction between two kinds of carbon atoms and CO2. In the process of oxidation reaction, the ketene structure generated by the reaction of two kinds of carbon atom and CO2 will be cracked into CO due to its instability, which completes the reaction process.

Key words: coke, dissolution loss reaction, mechanism, molecular simulation, charge density, pore diameter, adsorption

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