Heterogeneous catalysis, role chemicals

The authors are very grateful to many colleagues from academia and industry who shared their knowledge and expertise in kinetics and mass transfer. In particular the late Professor M.I. Temkin introduced one of the authors into the field of heterogeneous catalysis and chemical reaction engineering in the broader context of physical chemistry and practical industrial needs and was a role model as a scientist and a person. 

Gas-surface interactions and reactions on surfaces play a crucial role in many technologically important areas such as corrosion, adhesion, synthesis of new materials, electrochemistry and heterogeneous catalysis. This chapter aims to describe the interaction of gases with metal surfaces in terms of chemical bonding. Molecular orbital and band structure theory are the basic tools for this. We limit ourselves to metals. 

Besides the practical application, the diversity of nanostructured carbon allotropes makes nanocarbon also an ideal model system for the investigation of structure-function correlations in heterogeneous catalysis. Nanocarbons can be tailored in terms of their hybridization state, curvature, and aspect ratio, i.e., dimensions of stacks of basic structural units (BSU), Chapters 1 and 2. The preferred exposition of two types of surfaces, which strongly differ in their physico-chemical behavior, i.e., the basal plane and prismatic edges, can be controlled. Such controlled diversity is seldom found for other materials giving carbon a unique role in this field of basic research. The focus of this chapter is set on the most prominent representatives of the... 

The Second International Symposium on Heterogeneous Catalysis and Fine Chemicals was held in Poitiers (Futuroscope), France, October 2-5, 1990. Just as in the first symposium (held in Poitiers, March 1988) the aims were to illustrate the present day role played by heterogeneous catalysis in the synthesis of functional compounds and to discuss methods of research in this field. 

Heterogeneous thermal and photocatalysis are bound to play a key role in those solutions. However, while thermal heterogeneous catalysis is widespread in chemical industries, and photocatalysis not yet, there is still a strong demand in both areas for research in order to understand the process and its elementary steps as well as to rationally design the catalytic material. 

In heterogeneous catalysis reactants have to be transported to the catalyst and (if the catalyst is a porous, solid particle) also through the pores of the particle to the active material. In this case all kinds of transport resistance s may play a role, which prevent the catalyst from being fully effective in its industrial application. Furthermore, because appreciable heat effects accompany most reactions, heat has to be removed from the particle or supplied to it in order to keep it in the appropriate temperature range (where the catalyst is really fully effective). Furthermore, heterogeneous catalysis is one of the most complex branches of chemical kinetics. Rarely do we know the compositions, properties or concentrations of the reaction intermediates that exist on the surfaces covered with the catalytically effective material. TTie chemical factors that govern reaction rates under these conditions are less well known than in homogeneous catalysis. Yet solid catalysts display specificities for particular reactions, and selectivity s for desired products, that in most practical cases cannot be equaled in other ways. Thus use of solid catalysts and the proper (mathematical) tools to describe their performance are essential. 

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