Some aspects of catalyst characterisation and activity

Knowledge of the connection between catalyst structure and catalytic activity is reviewed, examples being selected from reactions involving monophastic catalysts (oxides and sulphides, metal single crystals, zeolites) and multiphasic catalysts (especially supported metals). Contributions to our knowledge from surface science, conventional structure and characterisation studies, EXAFS spectroscopy, and in situ methods of catalyst evaluation are considered. Evidence that reversible displacements of atoms in the active phase may occur during catalytic conversions is noted, as is the importance of permanently retained hydrocarbonaceous species in the establishment of reproducible catalytic activity in metals. Throughout, the complementary nature and roles of structural information and mechanistic studies is emphasized.