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Mechanistic kinetic modeling of the hydrocracking of complex feedstocks.

机译：复杂原料加氢裂化的力学动力学模型。

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摘要

Two separate mechanistic kinetic models have been developed for the hydrocracking of complex feedstocks. The first model is targeted for the hydrocracking of vacuum gas oil. The second one addresses specifically the hydrocracking of long-chain paraffins, but at a more fundamental level as compared to the first one. Both models are based on an exhaustive computer generated reaction network of elementary steps.;In the first model, the dehydrogenation/hydrogenation steps occurring on the metal sites to generate/consume the reactive olefinic intermediates are assumed to be very fast so that the acid site steps are considered as the rate determining steps. The frequency factors for acid site steps are modeled using the single-event concept and the activation energies based on the nature of the reactant and product carbenium ions.;This model utilizes a detailed composition of the vacuum gas oil characterized by 16 different molecular classes up to carbon number 40. These classes are divided into 45 subclasses by distinguishing the isomers of a class according to the number of methyl branches. The kinetic model is plugged into an adiabatic multi-bed trickle flow reactor model. The model contains 33 feedstock and temperature independent parameters which have been estimated from the experimental data.;The model has been used to study the effect of the operating conditions on the yield and composition of various products. A sensitivity analysis of the distribution of isomers of a class among its different subclasses has been performed showing that the total conversion increases when the content of isomers with a higher degree of branching is increased in the feed.;In the second model, the dehydrogenation/hydrogenation steps on the metal sites are also assumed to be rate determining. The rate coefficients for the dehydrogenation steps are modeled depending on the nature of the carbon atoms forming the double bond. The frequency factors for the acid site steps are modeled using the single-event concept. A more rigorous approach has been selected to model the activation energies of the acid site steps by implementing the Evans-Polanyi relationship. The 14 model parameters, which are independent of the temperature and feedstock composition, have been estimated from the experimental data. The model elucidates the effect of the relative metal/acid activity of the catalyst on the isomerization/cracking selectivities and on the carbon number distribution of the products.
机译：已经开发了两种独立的动力学模型用于复杂原料的加氢裂化。第一种模型的目标是真空粗柴油的加氢裂化。第二个专门解决长链烷烃的加氢裂化问题，但与第一个相比，其基础性更高。两种模型均基于详尽的计算机生成的基本步骤的反应网络。在第一种模型中，假定发生在金属位点以产生/消耗反应性烯烃中间体的脱氢/氢化步骤非常快，因此酸位点步骤被认为是速率确定步骤。使用单事件概念和活化能根据反应物和产物碳正离子的性质对酸位阶跃的频率因子进行建模;该模型利用了由16种不同分子类别表征的真空瓦斯油的详细组成至碳数40。通过根据甲基支链的数量区分一类异构体，将这些类分为45个亚类。将动力学模型插入绝热多床滴流反应器模型中。该模型包含33种原料和与温度无关的参数，这些参数已根据实验数据进行了估算。该模型已用于研究操作条件对各种产品的产量和组成的影响。已对一类异构体在其不同亚类之间的分布进行了敏感性分析，结果表明，当进料中具有较高支化度的异构体含量增加时，总转化率会提高。；在第二种模型中，脱氢/金属位置上的氢化步骤也被认为是决定速率的。根据形成双键的碳原子的性质对脱氢步骤的速率系数进行建模。使用单事件概念对酸位阶跃的频率因子进行建模。选择了一种更严格的方法来通过实现Evans-Polanyi关系来模拟酸位阶跃的活化能。根据实验数据估算了14个模型参数，这些参数与温度和原料组成无关。该模型阐明了催化剂的相对金属/酸活性对异构化/裂化选择性和产物的碳数分布的影响。

著录项

  • 作者

    Kumar, Hans.;

  • 作者单位

    Texas A&M University.;

  • 授予单位 Texas A&M University.;
  • 学科 Engineering Chemical.
  • 学位 Ph.D.
  • 年度 2006
  • 页码 195 p.
  • 总页数 195
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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