萘热解生焦初期的反应分子动力学模拟

Reactive molecular dynamics simulation in the early stage of coking process of naphthalene

油系针状焦由石油加工而成,属于高附加值产品,其市场价格相比普通焦高很多,研究针状焦具有较高的经济意义。为提升针状焦生产技术,采用分子模拟方法从分子水平深入研究针状焦生成机理。针状焦原料中含有较多的萘及其衍生物。为此,采用分子模拟的方法研究萘在热解生成针状焦初期的反应分子动力学。运用反应分子动力学模拟方法ReaxFF模拟该反应的分子动力学,并进行量子化学分析,推断得到萘分子在热解生焦初期的主要反应历程。考察萘分子结构性质和电荷分布发现,萘分子1号位和2号位的C-H键键能相近,强度相当,但1号位碳原子上分布的净电荷稍多,活性较强。反应分子动力学模拟结果表明,在热解生焦过程初期,萘先通过分子间氢转移反应引发生成自由基·C10H7,·C10H7与萘分子结合生成·C20H15,·C20H15被其周围的萘分子夺去一个氢原子,生成稳定的二聚物C20H14。

Oil needle coke which is of high value is processed from petroleum.Its market price is much higher than ordinary coke.So it is of high economic significance to study needle coke.In order to improve the needle coke production technology,the mechanism of needle coke formation is deeply studied from the molecular level.The needle coke raw material contains a large amount of naphthalene and its derivatives.So that molecular simulation methods were used to do research into reactive molecular dynamics of naphthalene in the early stage of coke formation.Reactive force field ReaxFF was used to simulate reactive molecular dynamics.And quantum chemistry was used to analyze the results.Reaction route of naphthalene in the early stage of coke formation was acquired.The structural properties and charge distribution of naphthalene were investigated.The C-H bond energies at position 1 and position 2 were similar.The charge distributed on the carbon atom at position 1 was slightly more and the activity was stronger.In the early stage of naphthalene coking process,the free radical·C10H7 was generated through intermolecular hydrogen transfer reaction.Naphthalene and·C10H7 react to form·C20H15.Then·C20H15 was deprived of a hydrogen atom by naphthalene to form stable dimer C20H14.