Theoretical Aspects Of Transition Metal Catalysis

Transition metal catalysis belongs to the most important chemical research areas because a ubiquitous number of chemical reactions are catalyzed by transition metal compounds. Many efforts are being made by industry and academia to find new and more efficient catalysts for chemical processes. Transition metals play a prominent role in catalytic research because they have been proven to show an enormous diversity in lowering the activation barrier for chemical reactions. For many years, the search for new catalysts was carried out by trial and error, which was costly and time consuming. The understanding of the mechanism of the catalytic process is often not very advanced because it is difficult to study the elementary steps of the catalysis with experimental techniques. The development of modern quantum chemical methods for calculating possible intermediates and transition states was a breakthrough in gaining an understanding of the reaction pathways of transition metal catalyzed reactions. This volume, organized into eight chapters written by leading scientists in the field, illustrates the progress made during the last decade. The reader will obtain a deep insight into the present state of quantum chemical research in transition metal catalysis.

Heterogeneous catalysis is a fascinating and complex subject of utmost importance in the present day. Its immense technological and economical importance and the inherent complexity of the catalytic phenomena have stimulated theoretical and experimental studies by a broad spectrum of scientists, including chemists, physicists, chemical engineers, and material scientists. Computational and theoretical techniques are now having a major impact in this field. This book aims to illustrate and discuss the subject of heterogeneous catalysis and to show the current capabilities of the theoretical and computational methods for studying the various steps (diffusion, adsorption, chemical reaction) of heterogeneous catalytic process involving zeolites, metal oxides, and transition metal surfaces. The book covers: the use of techniques of computational chemistry to simulate zeolites, metallic and bimetallic surfaces, and oxide-supported metals; the impact of simulation methods on the understanding of the diffusion and adsorption of molecules and cations within the pores of zeolites, and also on the adsorption of molecules on metal and metal-oxide surfaces; and the applications of quantum-mechanical methods to the study of the reaction mechanism and pathways of the adsorbed molecules. This book is recommended primarily to scientists and graduate students conducting research in the fields of heterogeneous catalysis and surface science. It will also be valuable to advanced undergraduate students wishing to become acquainted with the latest developments in these exciting fields of research, and to experimentalists seeking theoretical support for interpreting their results.

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.

This book focuses on the electronic properties of transition metals in coordination environments. These properties are responsible for the unique and intricate activity of transition metal sites in bio- and inorganic catalysis, but also pose challenges for both theoretical and experimental studies. Written by an international group of recognized experts, the book reviews recent advances in computational modeling and discusses their interplay using experiments. It covers a broad range of topics, including advanced computational methods for transition metal systems; spectroscopic, electrochemical and catalytic properties of transition metals in coordination environments; metalloenzymes and biomimetic compounds; and spin-related phenomena. As such, the book offers an invaluable resource for all researchers and postgraduate students interested in both fundamental and application-oriented research in the field of transition metal systems.

The main application of Transition Metal Sulphides (TMS) as solid catalysts is for production of clean fuels in petroleum refineries. The various feedstocks to be processed all contain more or less sulphur, included in highly stable heteroaromatic molecules. In order to meet the stringent specifications imposed worldwide nowadays on transportation fuels to reduce their environmental impact, catalytic hydroprocessing remains essential. In this process, sulphur is removed as H2S following the reaction between molecular hydrogen and the heteroaromatics. The reaction conditions and reaction medium composition are such that only TMS provide stable catalysts, generally supported on alumina. Both for their fundamental and applied interest, these fascinating systems are still the subject of a very significant research effort, while major advances have been made over the past 30 years, involving innovative preparation routes, sophisticated surface science experiments for characterisation, detailed kinetic and mechanistic studies, and state of the art DFT simulations giving unprecedented insight into the local structure as well as elementary steps at microscopic level. This book aims at providing a complete, comprehensive and updated survey of the field, useful for anyone involved: the student starting a research project, the academic researcher or the refinery engineer willing to deepen their knowledge on the catalytic as well as on the process aspects. 37 specialists from IFP Energies nouvelles, CNRS, or French universities have contributed, reporting a unique synthesis of the last 15 years of research. The preface written by Michèle Breysse, a well known leading scientist who devoted most of her fruitful career to this topic, puts this collective work into a meaningful historical perspective. Contents : Part 1. Fundamental Aspects: Insights from DFT calculations and experimental surface sciences. 1. Periodic trends in catalysis by sulphides. 2. Atomic scale structures of mixed lamellar sulphides. 3. Theoretical and microkinetic studies of hydrotreatment reactions. 4. Models of supported Co(Ni)MoS Catalysts. Part 2. Progress in the preparation and characterisation of industrial hydrotreating catalysts. 1. Principles involved in the preparation of hydrotreatment catalysts. 2. Progress in the preparation of new catalysts. 3. Progress in the preparation of catalysts with controlled acidity: case of aluminosilicate supports. 4. Activation and genesis of the active phase by sulfidation. 5. life cycle of an HDT catalyst. 6. Charaterisation of catalysts. Part 3. Applications to the production of clean fuels. 1. An overview of refining. 2. Deep desulphurisation of middle distillates. 3. Selective desulphurisation of catalytic cracking gasolines. 4. Hydrocracking. 5. Hydroprocessing and hydroconversion of residue fractions. 6. Hydrotreatment of vegetable oils. 7. Hydroconversion of coals. Conclusion.

This publication is the first to present the quantitative application of quantum chemistry to organometallic reactions. Great progress has been made in recent years in the calculation of transition states of organometallic conversions in both homo and heterogeneous catalysis. This volume, which contains seven contributions by leading scientists, deals with key reactions of homogeneous catalysis including oxidative addition, migratory insertions, 2+2 additions, the Wacker reaction, and epoxidation. The book provides experimental chemists with an up-to-date overview of the state of the art in this field, and will stimulate an adjustment of views previously based on semiempirical calculations. For researchers and advanced graduate students whose work involves organometallics and catalysis.

Atomically dispersed metal cations and small polyatomic cationic structures co-ordinated to the surface of porous matrices exhibit different properties from the same cationic species contained in a bulk oxide or supported on amorphous carriers. This subject is treated to an extensive review, showing how an understanding of it is essential to the development of a new generation of solid catalysts. There are also exciting opportunities to shape the catalytic properties of the transition metal cations in microporous and mesoporous matrices. The book covers both theoretical and experimental aspects, including the distribution of framework Al atoms in Si-rich zeolites, distribution and siting of charge-exchanged metal cations, electronic, adsorptive and catalytic properties of metal cations, and correlation of metal cation structure and siting with catalytic activity.

An expert overview of current research, applications, and economic and environmental advantages The study and development of new homogeneous catalysts based on first-row metals (Mn, Fe, Co, Ni, and Cu) has grown significantly due to the economic and environmental advantages that non-noble metals present. Base metals offer reduced cost, greater supply, and lower toxicity levels than noble metals?enabling greater opportunity for scientific investigation and increased development of practical applications. Non-Noble Metal Catalysis provides an authoritative survey of the field, from fundamental concepts and computational methods to industrial applications and reaction classes. Recognized experts in organometallic chemistry and homogeneous catalysis, the authors present a comprehensive overview of the conceptual and practical aspects of non-noble metal catalysts. Examination of topics including non-innocent ligands, proton-coupled electron transfer, and multi-nuclear complexes provide essential background information, while areas such as kinetic lability and lifetimes of intermediates reflect current research and shifting trends in the field. This timely book demonstrates the efficacy of base metal catalysts in the pharmaceutical, fine-chemical, and agrochemical industries, addressing both environmental and economic concerns. Providing essential conceptual and practical exploration, this valuable resource: -Illustrates how unravelling new reactivity patterns can lead to new catalysts and new applications -Highlights the multiple advantages of using non-noble metals in homogenous catalysis -Demonstrates how the availability of non-noble metal catalysis reduces costs and leads to immense savings for the chemical industry -Reveals how non-noble metal catalysis are more sustainable than noble metals such as palladium or platinum Non-Noble Metal Catalysis: Molecular Approaches and Reactions is an indispensable source of up-to-date information for catalytic chemists, organic chemists, industrial chemists, organometallic chemists, and those seeking to broaden their knowledge of catalytic chemistry.