宽温度范围下烷烃与OH自由基脱氢反应的理论研究

发布时间：2018-03-05 13:28

本文选题：烷烃　切入点：燃烧　出处：《大连理工大学》2016年硕士论文　论文类型：学位论文

【摘要】：世界范围内的化石能源中有三分之一是石油,其主要的成分是烃类,其中烷烃,环烷烃和芳香烃这三大结构最为重要和普遍。伴随汽车产业的快速发展,汽车作为化石能源燃烧的主要消耗者和污染的排放源,对发动机中的汽油和柴油的燃烧过程进行精确的控制,可大幅度的提高燃料的燃烧效率,降低污染排放,因此研究汽油和柴油在发动机中的详细燃烧机理是十分必要的。在燃烧领域,通常选取替代燃料来表征柴油和汽油的组分,对其进行反应机理研究,烷烃作为石油的主要成分,其结构简单,性质呈规律性变化,并且能够一定程度的表征柴油和汽油在发动机中的燃烧特性,是很好的表征模型。化学反应速率常数在科研工作和实际生产中的重要性,能够准确的测量速率常数和掌握它的变化规律是科学家们研究的热点。例如：燃烧机理领域,发动机设计,排放,以及相关的常用燃料进行改进这些在日常工业生产中很重要的领域,在这些领域中研究的出发点大多是从反应速率常数,也就是说,如果能够得到准确的相关化学反应速率,就可能在设计的原理上进行改进,使得生产流程效率更高,减少燃烧的浪费比例,降低污染产物排放的比率,真正实现高产率、高质量、低污染的工业流程,目前对化学速率常数的主要研究分为实验测量和理论预测。本文应用量子力学理论方法,全部计算在Gaussian 09中完成,选取BHHLYP/6-311G(d, p)基组优化几何构型,寻找反应过渡态,进行频率分析,确定反应体系势能面,得到从反应物经过过渡态抵达产物的反应路径,详细分析逐点的全部势能面信息。其次,应用改进的变分过渡态理论(ICVT)结合小曲率隧道效应校正(SCT)计算反应速率常数。在此基础上揭示具体的化学反应过程微观机理和准确的动力学性质。本文针对烷烃燃烧机理中的关键基元反应——烷烃与OH自由基的脱氢反应进行反应动力学研究,在298-2000K温度区间内,计算了C1.C14系列烷烃与OH自由基脱氢反应的准确的活化能信息,并且利用过渡态理论计算反应的速率常数。本研究选取的对象是C1.C14系列烷烃,包括了对缺乏实验数据与模拟预测的大分子的尝试,并且完成了低温与高温的全温度范围内的预测,首次针对烷烃与OH自由基的脱氢反应进行系统全面的反应动力学计算,对实际生产中关心的反应区间和反应成分,进行了准确的预测,对于系统把握发动机中燃烧的关键反应的规律有一定的指导作用,因此,将烷烃与OH自由基的脱氢反应在高温和大分子范围内进行反应速率的计算是十分有意义的。
[Abstract]:1/3 of the fossil energy sources worldwide are petroleum, the main components of which are hydrocarbons, among which alkanes, cycloalkanes and aromatic hydrocarbons are the most important and common structures. As the main consumer of fossil energy combustion and the emission source of pollution, automobile can control the combustion process of gasoline and diesel in the engine accurately, which can greatly improve the combustion efficiency of fuel and reduce the pollution emission. Therefore, it is necessary to study the detailed combustion mechanism of gasoline and diesel in the engine. In the field of combustion, alternative fuels are usually selected to characterize the components of diesel and gasoline, and the reaction mechanism is studied. Alkanes are the main components of petroleum. Its structure is simple, its properties change regularly, and it can characterize the combustion characteristics of diesel and gasoline in engine to a certain extent, which is a good characterization model. The importance of chemical reaction rate constant in scientific research and practical production. The ability to accurately measure the rate constant and understand its variation is a hot topic for scientists. For example, in the field of combustion mechanism, engine design, emissions, And related common fuels to improve these areas that are very important in daily industrial production, where the starting point is mostly from the reaction rate constant, that is, if you can get the exact rate of the chemical reaction. It is possible to improve the design principle, to make the production process more efficient, to reduce the proportion of waste from combustion, to reduce the emission rate of pollution products, and to realize the industrial processes with high yield, high quality and low pollution. At present, the main research on chemical rate constants is divided into experimental measurement and theoretical prediction. In this paper, the quantum mechanics method is used to calculate the chemical rate constants in Gaussian 09. The optimal geometric configuration of BHHLY P / 6-311G / d, p) basis set is selected to find the transition state of the reaction. The potential energy surface of the reaction system is determined by frequency analysis, and the reaction path from the reactant to the product through the transition state is obtained, and all the potential energy surface information is analyzed in detail. Secondly, Based on the modified variational transition state theory (ICVT) and small curvature tunneling effect correction (SCT), the reaction rate constant is calculated. On this basis, the microscopic mechanism and accurate kinetic properties of chemical reaction process are revealed. The kinetics of the dehydrogenation of alkanes with OH radicals was studied. In the temperature range of 298-2000K, the accurate activation energy information of the dehydrogenation of C _ (1) C _ (14) series alkanes with OH radical was calculated, and the rate constant of the reaction was calculated by using the transition state theory. The object of this study was C _ (1) C _ (14) series alkanes. Including the attempt of macromolecules lacking experimental data and simulated prediction, and the prediction of the whole temperature range of low and high temperature, the kinetics of dehydrogenation of alkanes with OH radical was calculated systematically and comprehensively for the first time. The accurate prediction of the reaction interval and reaction component concerned in actual production has a certain guiding function for the system to grasp the law of the key reaction of combustion in the engine, so, It is very meaningful to calculate the reaction rate of dehydrogenation of alkanes with OH radical in the range of high temperature and macromolecule.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：U473

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