Heterogeneously Catalyzed Oxidation Reactions Using ... - CHEC

Chapter 1
Introduction
With its great influence on society, heterogeneous catalysis has been a political issue for more than
100 years. Like many scientific areas, catalysis also has a tragic history. The Haber‐Bosch process
developed for ammonia synthesis kept the German artillery firing almost 100 years ago and around
25 years later, the coal liquefaction processes by Bergius‐Pier and Fischer‐Tropsch allowed the
German tanks to keep rolling causing death and suffering for millions. The societal impact of catalysis
has shifted by now. Haber‐Bosch is feeding the world and Fischer‐Tropsch is intended to make the
world a greener place. Indeed, catalysis is a key to the development of environmentally benign and
sustainable processes and a cornerstone in the concept of “Green Chemistry” [1‐3].
First and foremost, catalysis is part of our everyday life and contributes substantially to our
societal wealth. It is therefore not surprising that many basic processes e.g. hydrogenation and
oxidation reactions are of constant interest both in academia and industry bringing forth more and
more effective catalysts, new technologies and an ever increasing in‐depth understanding of
fundamental catalytic principles. Heterogeneous catalysis taking place at the interface between two
phases is difficult to study. Detailed knowledge is available on important gas‐phase reactions like
ammonia synthesis and CO oxidation and was recently awarded with the Nobel prize for Gerhard
Ertl [4].
The present thesis concentrates on studying liquid phase oxidation catalysis. Oxidation
catalysis is a mandatory tool (Figure 1‐1) for the production of fine chemicals [5], functionalization of
petrochemical feedstocks [6] and for harmful emission control [7] and will contribute to the
development of new target compounds from biomass [8]. The capability of catalysts to activate
environmentally benign and inexpensive oxidants such as hydrogen peroxide and especially
molecular oxygen has added a great deal to the attractiveness of catalysts eliminating toxic and
atom‐inefficient oxidants like hexavalent chromium. On an industrial scale, both homogeneous and
heterogeneous catalysts found their field of application. Homogenous transition metal catalysts
being present in the same phase as the substrate(s) afford high reaction rates and variation of the
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