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首页> 外文学位 >Ab initio calculations in heterogeneous and homogeneous catalysis: I. Methanol to gasoline with ZSM-5. II. Carbonyl ligand effects on metal-metal bonds.
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Ab initio calculations in heterogeneous and homogeneous catalysis: I. Methanol to gasoline with ZSM-5. II. Carbonyl ligand effects on metal-metal bonds.

机译：在非均相和均相催化中从头算的计算：I.用ZSM-5甲醇制汽油。二。羰基配体对金属-金属键的影响。

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摘要

his thesis is composed of two studies in catalysis. The first is an exploration, using computational techniques, of the mechanism for the first carbon-carbon bond formation in the Methanol to Gasoline (MTG) reaction. The second is a study of the factors important to the understanding of ligand effects on metal-metal bonds, and in particular, to metal clusters.;Three possibilities were considered as ways to activate a carbon in the MTG process prior to formation of C2 or higher hydrocarbons. These were a free radical mechanism, a surface ylide mechanism, and a possible defect site which might lead to steric crowding of CH;Although the free radical mechanism was found to be thermodynamically within the parameters of the MTG process, it contained a high transition state. Consideration of the molecules available prior to hydrocarbon build-up and their specific electronic structure, led to the view that the available carbon atoms (methanol, dimethyl ether, etc.) were unlikely to be activated by a free radical intermediate.;The surface-stabilized ylide which has been proposed as an intermediate by many was studied to determine if in fact the ylide was stabilized. The total energy of the ylide was compared to that of the naked site on the zeolite and free methylene. Free methylene ranged, depending on the geometry of the ylide, between 50 and 80 kcal more stable. These numbers are qualitatively correct, but more electron correlation would have to be incorporated in the calculation to get an accurate value for the destabilization.;Starting from a defect site, two CH;The second study involved determining the effects of colinear carbonyl ligands on osmium-osmium bonds. Calculations at the Dissociation Consistent CI level showed that the ligands were weakening the metal-metal
机译：他的论文由两项催化研究组成。首先是使用计算技术探索甲醇到汽油（MTG）反应中第一个碳-碳键形成的机理。第二部分是研究对于理解配体对金属-金属键，特别是对金属簇的影响至关重要的因素;三种可能性被认为是在MTG过程中在C2或C2形成之前活化碳的方式。高级烃。这些是自由基机理，表面内立素机理以及可能导致CH的空间拥挤的可能缺陷位点;尽管发现自由基机理在MTG过程的参数范围内是热力学的，但它包含高过渡态。考虑到碳氢化合物积累之前可用的分子及其特定的电子结构，导致人们认为可用的碳原子（甲醇，二甲醚等）不太可能被自由基中间体活化。研究了许多人提议作为中间体的稳定的叶立德，以确定实际上叶立德是否稳定。将叶立德的总能量与沸石和游离亚甲基上裸露位置的总能量进行比较。游离亚甲基的范围取决于叶立德的几何形状，更稳定在50至80 kcal之间。这些数字在质量上是正确的，但是在计算中必须包含更多的电子相关性才能获得失稳的准确值。从缺陷位置开始，两个CH开始；第二项研究涉及确定共线性羰基配体对的影响-os键。在解离一致CI水平上的计算表明，配体正在削弱金属-金属

著录项

  • 作者

    Miller, Ann Elizabeth.;

  • 作者单位

    California Institute of Technology.;

  • 授予单位 California Institute of Technology.;
  • 学科 Physical chemistry.;Chemical engineering.;Organic chemistry.
  • 学位 Ph.D.
  • 年度 1993
  • 页码 139 p.
  • 总页数 139
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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