ABSTRACT
A. Introduction From the point of view of thermodynamics, most of the other elements and a great many chemical compounds including practically all organic substances are not stable with respect to oxygen. However, a small portion of them do react spontaneously at room or even slightly elevated temperatures. The high bond energy in 02 is one of the reasons that the activation energy of uncatalyzed oxidation reactions is high and at moderate temperatures catalyst must be used. One of the essential functions of the catalyst in oxidation reactions is the activation of oxygen. The way in which oxygen becomes activated is a crucial problem in oxidation catalysis. Generally speaking, oxygen activation is considered to occur by its adsorption and/ or incorporation into the oxide crystal lattice, the surface atoms of which may also participate in the catalytic reaction. Therefore the study of the behavior and properties of oxygen adsorbed on the catalyst as well as surface oxygen atoms in oxides is essential for an understanding of the catalytic oxidation processes. In the present chapter these topics are discussed separately for the two main groups of oxidation catalysts: the oxides and the metals.
