Heterogeneous Catalysis for the Synthetic Chemist

Robert L. Augustine

• Publisher: CRC Press
• Year: 2020
• Print ISBN: 9781138034778
• eBook ISBN: 9781000148213
• Edition: 1
• Topic: Physical Sciences
• Subtopic: Chemistry
• Index: Chemistry

This work delineates the effect of different reaction variables on the outcome of heterogeneously catalyzed reactions, and explains how to optimize the product yield of specific compounds. Metal catalysis, simple and complex oxides, zeolites and clays are discussed, both as catalysts and as potential supports for catalytically active metals.

1

Introduction

For the typical synthetic chemist the use of a heterogeneously catalyzed reaction usually involves the finding of a seemingly appropriate “recipe” to follow and the resignation to settle for whatever yield may be obtained. With other synthetically viable reactions a basic mechanistic understanding can frequently be used to modify the reaction conditions in order to optimize product formation. Such an approach is not readily applied to heterogeneously catalyzed processes because the type of mechanistic understanding needed by the synthetic chemist is not yet commonly available for this type of reaction. Further, the average synthetic chemist has little experience in dealing with heterogeneous systems so basic factors such as heat and mass transport, and the effect of the various reaction parameters on these factors are generally not understood.

At present the most important synthetic use of heterogeneous catalysis is for the hydrogenation and hydrogenolysis of various organic functional groups. Other reactions, such as catalytic oxidation and C-C bond formations using surface-promoted organometallic reactions, are used only infrequently. To develop these reactions as viable synthetic procedures, though, will require that all of the facets of heterogeneous catalysis be more fully understood by the practicing chemist.

This book is written with this goal in mind. It is based on the assumption that the reader will have had little, if any. experience with heterogeneous systems. The first part of the book is concerned with the basic concepts of heterogeneous catalysis and begins with a general discussion of catalysis, how catalysts function, the nature of the active sites on a catalyst surface and how they promote a reaction. This is followed by a treatment of the heat and mass transport aspects in heterogeneous systems and how these factors can be recognized. Next is a presentation of the reaction parameters typically found in heterogeneous catalysis (temperature, pressure, solvent, etc.) and a description of how cadi can affect the mass transport in a heterogeneous system. A discussion of the type of reactors used for heterogeneously catalyzed reactions follows. A basic treatment of reaction kinetics as applied to these systems concludes the first section. The second part of the book is devoted to the catalyst itself with chapters on metal catalysts, the materials used to support them, oxide catalysts and zeolites. The final section deals with heterogeneously catalyzed reactions of interest to the synthetic chemist.

This information is intended to provide a basic foundation for developing a working understanding of heterogeneous catalysis and heterogeneously catalyzed reactions. Hopefully, this will encourage synthetic chemists to use such processes more frequently and, thus, increase the application of such systems to the preparation of a variety of materials.

The literature of heterogeneous catalysis is extensive so no attempt has been made to provide a complete literature review of any of the topics covered. Sufficient references are provided, though, to give an entree into these topics so that further information may be obtained as needed.

Of the numerous texts in this area, the classic book by Bond,¹ his more recent abbreviated version,² and those of Gasser³ and Gates⁴ provide a basic, general treatment of heterogeneous catalysis. Satterfield’s⁵ text gives a more practical treatment from an engineering perspective. While all of these texts provide some discussion of the kinetics of heterogeneously catalyzed processes Boudart and Djega’Mariadassou⁶ have written the definitive treatment of this topic. The book by Anderson⁷ provides an introduction into the use of metal catalysts with good discussions of preparation procedures and support materials. Those by Delannay,⁸ Jones and McNicol,⁹ Thomas and Lambert.¹⁰ Anderson¹¹ and Anderson and Dawson^12,13 provide information on the techniques used for catalyst preparation and characterization. The procedures for speciiic reactions can be found in those books describing the catalytic hydrogenation and hydrogenolysis of organic functional groups.^14–22 Discussions of catalytic oxidations, although not exclusively heterogeneously catalyzed, have also been published.^23,24 While some reference will be made in the following sections to these general texts, most of the references will be from the original literature.

References

1. 1. G. C. Bond, Catalysis by Metals, Academic Press, New York, 1962.
2. 2. G. C. Bond, Heterogeneous Catalysis, Principles and Applications, Oxford University Press, Oxford, 1987.
3. 3. R. P. H. Gasser, An Introduction to Chemisorption and Catalysis by Metals, Clarindon Press, Oxford, 1985.
4. 4. B. C. Gates, Catalytic Chemistry, Wiley, New York. 1992.
5. 5. C. N. Satterfield, Heterogeneous Catalysis in Practice, McGraw Hill, New York, 1980.
6. 6. M. Boudart and G. Djega’Mariadassou, Kinetics of Heterogeneous Catalytic Reactions, Princeton University Press, Princeton. 1984.
7. 7. J. R. Anderson, Structure of Metallic Catalysts. Academic Press, New York, 1975.
8. 8. F. Delannay, Characterization of Heterogeneous Catalysis, (Chemical Industries Series, Vol. 15). Dekker, New York, 1984.
9. 9. A. Jones and B. D. McNicol, Temperature Programmed Reduction for Solid Material Characterization, (Chemical Industries Series, Vol. 24), Dekker, NewYork, 1986.
10. 10. J. M. Thomas and R. M. Lambert, Characterization of Catalysts, Wiley, New York, 1980.
11. 11. R. B. Anderson, Experimental Methods in Catalysis Research, Vol. 1, Academic Press, New York, 1968.
12. 12. R. B. Anderson and P. T. Dawson, Experimental Methods in Catalysis Research, Vol, II, Academic Press, New York. 1976.
13. 13. R. B. Anderson and P. T. Dawson, Experimental Methods in Catalysis Research, Vol. 111. Academie Press, New York, 1976.
14. 14. R. L. Augustine, Catalytic Hydrogenation, Techniques and Applications in Organic Synthesis. Dekker, New York. 1965.
15. 15. P. N. Rylander, Catalytic Hydrogenation over Platinum Metals, Academic Press, New York, 1967.
16. 16. P. N. Rylander, Catalytic Hydrogenation in Organic Synthesis, Academic Press, New York, 1979.
17. 17. P. N. Rylander, Hydrogenation Methods. Academic Press, New York, 1985.
18. 18. M. Freifelder, Practical Catalytic Hydrogenation, Wiley, New York, 1971.
19. 19. P. N. Rylander, Organic Synthesis with Noble Metal Catalysts, Academic Press, New York, 1973.
20. 20. A. P. G Kieboom and F. VanRantwijk, Hydrogenation and Hydrogenolysis in Synthetic Organic Chemistry, Delft University Press, 1977.
21. 21. M. Bartok, Stereochemistry of Heterogeneous Metal Catalysis, Wiley, New York. 1985.
22. 22. L. Cerveny (Ed.), Catalytic Hydrogenation. (Studies in Surface Science and Catalysis, Vol. 27), Elsevier, Amsterdam. 1986.
23. 23. R. A. Sheldon and J. K. Kochi, Metal Catalyzed Oxidations of Organic Compounds, Academic Press, New York, 1981.
24. 24. G. I. Golodcts, Heterogeneous Catalytic Reactions Involving Molecular Oxygen (Studies in Surface Science and Catalysis, Vol. 15), Elsevier, Amsterdam, 1983.

SECTION ONE




Basic Concepts

2
Catalysis

A catalyst is a substance that increases the rate at which a chemical reaction approaches equilibrium without, itself, becoming permanently involved in the reaction. The key word in this definition is permanently since there is ample evidence showing that the catalyst and the reactants interact before a reaction can take place. The product of this interaction is a reactive intermediate from which the products are formed. This substrate:catalyst interaction can take place homogeneously with both the reactants and the catalyst in the same phase, usually the liquid, or it can occur at the interface between two phases. These heterogeneously catalyzed reactions generally utilize a solid catalyst with the interaction taking place at either the gas/solid or liquid/solid interface. Additional phase transport problems can arise when a gaseous reactant is also present in the liquid/solid system.

Since a catalyst merely increases the rate of a reaction it cannot be used to initiate a reaction that is thermodynamically unfavorable. The enthalpy of the reaction as well as other thermodynamic factors are a function of the nature of the reactants and the products only and, thus, cannot be modified by the presence of a catalyst. Kinetic factors, such as the reaction rate, activation energy, nature of the transition state, and so on, are the reaction characteristics that can be affected by a catalyst.

Effe...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Dedication
• Foreword
• Preface
• Table of Contents
• Original Half Title
• 1 Introduction
• Section One Basic Concepts
• Section Two The Catalyst
• Section Three Reactions
• Index