On the Surface Chemistry of Iron Oxides in Reactive Gas Atmospheres

Abstract

Heterogeneous catalysis is based on the generation and subsequent combination of chemical species retained on the surface of a catalytic solid. Elementary reaction steps, that is, the dissociation of reactants and association to products, take place at the solid–gas or solid–liquid interface. Therefore, maximizing the accessible specific catalytic surface area, by reducing primary particle sizes, increases the (weight based) catalyst activity and results in higher material efficiency. However, surface and electronic properties of solids are often also significantly altered with decreasing particle sizes.[1,2] This results in size-dependent catalytic performance, better known as the particle size effect.[3–5] Although this effect has been well documented for many catalytic reactions, the exact underlying reasons for the different performance are often more difficult to access.