On the nature of isolated active sites in open-structure catalysts for the aerial oxidation of alkanes

Unique insights into structural aspects of ternary and quaternary oxide phases of selective oxidation catalysts containing bismuth and molybdenum are obtainable via high-resolution transmission electron microscopy. Some of these are summarised in relation to the facile loss of structural oxygen during the course of catalytic action. Recent advances in scanning transmission electron microscopy that promise to elucidate the structures of new catalysts are briefly discussed. The paper deals mainly with in situ studies (using X-ray absorption fine structure) of single-site oxidation catalysts and, in particular, with regio- and shape-selective oxidation of n-alkanes using Co-III (Mn-III)-AlPO-18 and AlPO-36 catalysts.