Theoretical Aspects of Heterogeneous Catalysis

Catalysis involves just about every field of scientific study. This means that a multidisciplinary approach is needed in catalytic studies. Catalysis involves breaking and forming new bonds and this requires an under­ standing of either adsorption by bonding to an extended structures or bonding in a coordination sphere. Any understanding of catalytic action must necessarily involve an understanding of this bonding. Even 200 years ago scientists were aware that a properly treated mate­ rial, such as charcoal, could adsorb an enormous quantity of gas. In 1812, de Sassasure (English translation, Annal Philosphy, 6, 241 (1815» pro­ posed that the ability of a material to increase the rate of chemical reac­ tion was due to adsorption of the material in the fine structure of the solid so that the concentrations of the reactants were significantly increased, and this increase in concentration led to an increase in reaction rate. During the 1800s, little advance was made in the understanding of adsorp­ tion.

1 A Theoretical View and Approach to the Physics and Chemistry of Zeolites and Molecular Sieves.- Quantum Mechanical Description of Al-Site-Related Properties in Zeolites.- Statistical Mechanics and Molecular Dynamics Simulations Applied to a Water-Ferrierite System.- 2 Conceptual Background for the Conversion of Hydrocarbons on Heterogeneous Acid Catalysts.- Nomenclature and Representation of Alkylcarbenium and Alkylcarbonium Ions Relevant to Alkane Conversion.- Relative Stabilities of Alkylcarbenium and Alkylcarbonium Ions.- Rearrangements of Acyclic Alkylcarbenium Ions in Superacids.- Alkylcarbenium Ions on the Surface of Heterogeneous Catalysts.- Carbocation Chemistry and Bifunctional Conversion of Short-Chain Alkanes.- Carbocation Chemistry and Bifunctional Conversion of Long-Chain Alkanes.- General Conclusions.- 3 The Role of Next Nearest Neighbors in Zeolite Acidity and Activity.- The Aluminosilicate Active Site.- Buffered Behavior and Zeolite Structure.- Stability Criteria and the Next-Nearest-Neighbor Model.- Paraffin Cracking Activity.- Cumene Cracking Activity.- Summary and Conclusions.- 4 Electronegativity Equalization, Solid-State Chemistry, and Molecular Interactions.- Electronegativity of an Atom in a Molecule.- Explicit Expression for the Effective Electronegativity.- The Electronegativity Equalization Method (EEM).- The Solid State.- Molecular Interactions.- Framework: Intrinsic Properties.- Framework: Molecular Interactions.- Brønsted Acidity: Intrinsic Properties.- Brønsted Acidity: Molecular Interactions.- The Active Site.- 5 Quantum-Chemical Studies of Zeolites.- Zeolite Models and Quantum-Chemical Methods.- Zeolite Properties.- Interaction of Zeolite Sites with Molecules.- Conclusions.- 6 Theoretical Studies of Transition Metal SulfideHydrodesulfurization Catalysts Suzanne Harris.- Periodic Trends in the HDS Activity of Simple TMS.- Promoted TMS Catalysts.- Electronic Structure of the Simple and Promoted TMS.- Structural Effects in Layered TMS.- Active Site Theory.- Conclusions.- 7 Factors Affecting the Reactivity of Organic Model Compounds in Hydrotreating Reactions.- General Features.- Reactivity of Aromatic Molecules.- Reactivity of Saturated Molecules.- Theoretical Modeling of the Reactivity.- Conclusions.- 8 Theoretical Investigation of Metal-Support Interactions and Their Influence on Chemisorption.- Experimental Investigations of Geometric Structures and Electronic Properties of Metal-Support Systems: Support Influence on Adsorbates.- The Support Influence on Chemisorption.- Surface Modeling and Computational Methods.- Metal-Support Interfaces and Support Influence on Chemisorption: Recent Theoretical Results.- Conclusions.- Note Added in Proof.- 9 Mechanisms and Intermediates of Metal Surface Reactions: Bond-Order Conservation Viewpoint.- The BOC-MP Model of Chemisorption.- Mapping of Surface Reactions.- Concluding Remarks.- 10 Structure and Electronic Factors in Heterogeneous Catalysis: C?C, C?O, and C–H Activation Processes on Metals and Oxides.- Atom Superposition and Electron Delocalization Molecular Orbital (ASED-MO) Approach.- Studies in Bond Activation.- Acetylene Bonding to Transition Metals: Structure and Electronic Effects.- CO Binding to Transition Metal Surfaces: A New Interaction.- CO Binding to ZnO and Surface Ion Relaxations.- CH Activation in Alkanes and Alkenes.- Conclusions.- 11 Application of Band-Structure Calculations to Chemisorption.- Method of Calculation.- Atomic Adsorbates.- Molecular Stereochemistry.- CO Adsorption.- Saturated Hydrocarbons.- EthyleneAdsorption.- Chemisorbed Butadiene.- Concluding Remarks.- 12 Quantum-Chemical Studies of the Acidity and Basicity of Alumina.- Acid-Base Properties of ?-Alumina.- Structure of Acidic and Basic Sites.- Models for Molecular Orbital Calculations of Alumina.- Types of Surface Hydroxyls.- Brønsted Acidity.- Basicity.- Lewis Acidity.- Conclusions.