ABSTRACT
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Heterogeneous catalysis occurs at the surface of solids. To describe the overall catalytic process it is obvious that one must consider fluid-phase transport of reactants to, and products away from, the solid surface. However, it is also true that, in the case of oxide materials, solid-phase transport of defects must be considered if we are to have a full description of the processes occurring at the surface. Furthermore, such defects, when present at the surface of the oxide, play a very important role in determining the catalytic activity of the solid. The nature of these surface defects is strongly related to the bulk defect chemistry of the solids. In this chapter we describe the bulk defect chemistry of solids and discuss the role of this defect chemistry in determining defect transport and electrical conductivity. We conclude the chapter by looking at the use of oxide membranes in chemical reactors.
