Mixed Metal Oxides

Mixed-metal oxides are a class of widely used catalysts. Industrial applications cover a wide range of relevant areas from acido-base to selective oxidation reactions and from petrochemistry to environment protection. This chapter first introduces the uses of mixed-metal oxide in catalysis and their characteristics, with focus on their multifunctional behavior as the key feature, also presenting the open fundamental questions regarding their reactivity and from an industrial perspective. Subsequently, their bulk and surface structure are introduced, with focus on aspects such as microstructure, strains and defects, and surface reconstruction and relaxation which are relevant for their catalytic behavior. Then the characteristics of low-dimensional metal oxide nanostructures are discussed to show their perspective on catalysis by metal oxide. The final part deals with the catalytic properties of these materials, with focus on the relation between redox, acido-base properties, and reactivity, highlighting how these aspects have to be put in relation with the possible presence of multiple pathways of reaction. The influence of them on the catalyst characteristics and of the feed composition, including the role of chemisorbed species on the surface reactivity is described.