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Abstract

Many catalyst systems used in selective oxidation of small molecules are bulk oxides with complex compositions and excessive chemical complexity. Concepts of "lattice oxygen" availability, "site isolation" and "phase co-operation" have driven the technical development in the past. The functional analysis of such systems is, however, still in its infancy as the application of model systems is barely possible and few techniques are available giving access to the details of the real structure (defects) that govern the operation of these systems. The application of a combination of in-situ techniques allows insight into the structural dynamics of these systems. Even in the simple example case of MoO3 the definition of the matrix material hosting the active sites is different from a priori assumptions derived from structural analysis of the as-synthesized catalysts. It is further possible to adress the electronic structure of a working catalyst. Using copper/oxygen as example, transient oxygen species were identified that are directly responsible for selective oxidation. Such species were characterised before by surface science experiments.