Volume Editors' Introduction

Abstract

In this volume of Comprehensive Inorganic Chemistry, we focus on solid catalysts of inorganic nature, that is, materials containing at least one metallic element. In Section 7.01, we give a detailed introduction of heterogeneous catalysis, including the definition of catalysis: a phenomenon in which a substance, the catalyst, accelerates chemical reactions without being consumed in the process. Catalysts are indispensable. In 2013, an estimated 85–90% of all chemical products are manufactured in catalytic processes. These products are transportation fuels, bulk and fine chemicals, or materials such as polymers. In particular, catalysts play a very important role in environmental applications, such as the automotive exhaust converter. In heterogeneous catalysis, the catalyst is in a different phase than the reactants, contrary to homogeneous catalysis (Volume 6). It is a solid material, whereas the reactants are either in the gas or in the liquid phase. Heterogeneous catalysts are nanosized particles, often stabilized by a support. They can be metals, metal oxides, zeolites, sulfides, carbon-based materials, and also metal carbides, nitrides, phosphides, chlorides. Chapter 7.01 introduces catalysis as a concept, and places it briefly into context. Chapters 7.02 and 7.03 present the molecular description that forms the basis for the potential energy considerations and the kinetic descriptions. Kruse and co-workers first describe elementary reaction steps such as adsorption, dissociation, reaction, and desorption on some well-defined metal surfaces, along with some of the typical spectroscopic and imaging methods used in surface science. A catalytic reaction mechanism is a sequence of elementary steps, and the reaction rate of the entire process is the resultant of those of the individual steps. In the chapter 7.03, Zaera discusses the kinetics of mechanisms on the idealized surfaces of model systems. These two other rather elementary chapters illustrate the power of surface science in unraveling catalytic mechanisms and in providing kinetic and thermodynamic data including activation barriers and heats of adsorption. Wet chemistry metal nanoparticle preparations and the nature of the solid–liquid interface is dealt with in Chapter 7.04 and attention to seeing catalyst particles in all of their morphologic detail using imaging methods is the subject of Chapter 7.05. Supported oxides as catalysts with the emphasis on monolayer systems, their preparation, and industrial use are treated in Chapters 7.06 and 7.07. Heteropoly oxidic compounds and their use in catalysis are dealt with in Chapter 7.08. Solid acids, zeolites, and mesoporous materials are discussed in Chapters 7.09 (concepts), 7.10 (characterization an catalysis in zeolites) and 7.11 (micro- and mesoporous compounds). Sulfides, carbon polymorphs, and carbides and nitrides in catalysis are covered in Chapters 7.12 (hydrotreating reactions), 7.13 (coke and deactivation), and 7.14 (carbides as co-catalysts). Computational modeling in catalysis is important nowadays and four chapters deal with it in detail. Chapter 7.15 presents an introduction to the theoretical foundations, whereas Chapter 7.16 details DFT calculations on catalysts. Chapter 7.17 treats theory and practice of the Haber–Bosch process, and in Chapter 7.18, the computational modeling of reacting systems in presented. The last part of this volume deals with catalysis in environmental and energy technology. In Chapter 7.19, the now famous three-way catalyst for cleaning automotive exhaust is presented, whereas an overview of the cobalt and iron catalysts used in Fischer-Tropsch synthesis is given in Chapter 7.20. Biomass as a renewable feedstock for energy and chemicals is treated in Chapter 7.21, whereas the last chapter (Chapter 7.22) of the volume is devoted to photocatalysis and water splitting using solar energy. The editors believe that the valuable collection of chapters in this volume gives an excellent impression on the state of knowledge in heterogeneous catalysis. They are very grateful to the authors for writing these authoritative overviews.