Chapter 5 X‐ray Diffraction

Powder X‐ray diffraction (XRD) provides information about phases and sizes of particles in solid catalysts, including characterization of the constitution and structure of the catalytically active species determined while the catalyst is functioning. This chapter includes a summary of the information provided by XRD, highlights some physical principles of diffraction that are needed to evaluate XRD data, and describes how nanostructural information about catalytically active materials can be determined from the data. Also included are a description of XRD instrumentation and an evaluation of the recent literature regarding experimental strategies and examples of catalysts that have been investigated with this technique. A major conclusion is that XRD data recorded under catalytic reaction conditions are useful for the structural and morphological characterization of solid catalysts, and XRD is augmented enormously when combined with other techniques for elucidating structures of working catalysts at length scales different from that of XRD.