Struktur‐Aktivitäts/Selektivitäts‐Beziehungen von Oxidationskatalysatoren

Abstract

Structure‐Activity/Selectivity Correlation of Oxidation CatalystsVarious reactive forms of oxygen are active in the selective oxygen functionalization of olefins and aromatic compounds.These forms are different on different crystal faces of transition metal oxides as shown by their different cation‐oxygen bond lengths. Therefore, face specifity of transition metal oxides as catalysts can be expected for the selective oxidation of hydrocarbons.Furthermore, the reactivity of the framework oxygen in the transition metal oxides for selective oxygen functionalization of hydrocarbons is dependent on the nature of the catalytic cycle (one‐ or two‐electron‐processes).Therefore, structure sensitivity of oxidation catalysts on the selectivity of transition metal oxides as oxidation catalysts is possible. Starting from this concept the following phenomena of the activity/selectivity relations are discussed for the most important industrial oxidation catalysts: —ensemble effects on the selectivity of supported Ag catalysts for the oxidation of ethylene to ethylenoxide. —face specifity of multicomponent Bi/Mo‐oxide catalysts in the selective oxidation of propylene to acrolein and in the ammoxidation of propylene. —structure sensitivity of V2O5‐containing catalysts in the oxidation of aromatic compounds.