In situ combined X-ray absorption spectroscopic and X-ray diffractometric studies of solid catalysts

The merits of employing combined in situ X-ray absorption spectroscopy (XAS) and X-ray diffractometry (XRD) are described by reference to a number of examples, which encompass: (i) crystallisation of molecular sieve catalysts; (ii) determination of the atomic architecture of active sites in CoALPO and MnALPO catalysts; (iii) the thermal stability and change of structure in the immediate vicinity to (and at a distance away from) transition-metal-ion active sites in microporous catalysts; (iv) subtle changes in electronic state (of copper active sites) in hydrotalcite-based catalysts for NOx elimination; (v) charting the entire cycle of preparation, use and regeneration of isolated Ti(IV)-centred active sites on mesoporous silica supports for the epoxidation of alkenes; and (vi) characterising the nature of bimetallic and other active cluster catalysts supported on silica. Recent developments in technique, notably the merits of energy-dispersive X-ray diffraction (which permit in situ studies with the use of stainless steel containers) are also highlighted.