基于ReaxFF MD方法模拟汽油中C6模型化合物的氧化裂解特性

摘要/Abstract

摘要： 分别选取正己烷、2-甲基戊烷、2,3-二甲基丁烷、环己烷、甲基环戊烷、1-己烯作为汽油中C₆组分的模型化合物，采用ReaxFF MD方法模拟了其在温度为3000 K及O₂消耗当量比（反应的实际O2消耗量与理论O₂消耗量之比）为1.0条件下的氧化裂解过程，统计了系统中反应物、产物(H₂O，CO，CO₂₎、关键自由基和中间体（C₂H₄，C₃H₆，.CH₃，CH₂O）含量随时间的变化情况，并对CH₂O和CO进行了敏感性分析，分析了6种C₆组分氧化裂解的初步反应路径，以及统一的后续氧化裂解反应路径。模拟结果表明：反应开始时，6种C₆组分均同步发生裂解和氧化反应；但在反应200 ps内，6种C6组分均主要发生裂解反应，生成C₂H₄，C₃H₆，.CH₃等自由基和中间体；C₆组分的分子结构会影响其裂解生成含碳自由基或中间体的浓度峰值，但不同体系中同种自由基或中间体浓度峰值的出现时间相近；截至反应2000 ps时，C₆组分中C元素的转化程度略高于H元素。敏感性分析发现：CH₂O主要由CH₃O.脱.H和CH₃O₂.脱.OH产生，并通过进一步脱.H生成.CHO而消耗；CO主要通过.CHO脱.H产生，并通过与.OH和HO₂.发生氧化反应而消耗。

关键词: C6烃类, ReaxFF MD, 分子模拟, 氧化裂解, 反应机理

Abstract: n-Hexane, 2-methylpentane, 2,3-dimethylbutane, cyclohexane, methylcyclopentane, and 1-hexene were selected as model compounds for the C6 component in gasoline. The ReaxFF-MD method was used to simulate their oxidative cracking process at a temperature of 3000 K and an equivalent ratioof O₂ consumption of 1.0. The changes in the content of reactants, products (H₂O, CO, CO₂), key free radicals, and intermediates (C₂H₄, C₃H₆, .CH₃, CH₂O) in the system over time were statistically analyzed, and sensitivity analysis was conducted on CH₂O and CO. The preliminary reaction pathways for the oxidative cracking of six C₆ components were analyzed, as well as a unified subsequent oxidative cracking reaction pathway. The simulation results indicate that at the beginning of the reaction, all six C₆ components undergo simultaneous cracking and oxidation reactions;but before 200 ps of reaction, all six C₆ components mainly undergo cleavage reactions, and the generated free radicals and intermediates are mainly C₂H₄, C₃H₆, .CH₃; the molecular structure of C₆ component can affect the concentration peak of carbon containing free radicals or intermediates generated by its cracking, but the occurrence time of the same type of free radical or intermediate concentration peak is similar in different systems; as of 2000 ps of reaction, the conversion degree of C element in C₆ component is slightly higher than that of H element. Sensitivity analysis revealed that CH₂O is mainly produced by the dehydrogenation of intermediates CH₃O. and CH₃O₂., and is consumed through the dehydrogenation to form .CHO; CO is mainly produced through .CHO dehydrogenation and consumed through oxidation reactions with .OH and HO₂..

Key words: C6 hydrocarbons, ReaxFF MD, molecular simulation, oxidation and cracking, reaction mechanism

穆佳昕王俊张然杨鹤. 基于ReaxFF MD方法模拟汽油中C6模型化合物的氧化裂解特性[J]. 石油炼制与化工, 2025, 56(8): 48-58.

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