Inelastic Incoherent Neutron Scattering in Catalysis Research

Inelastic, incoherent neutron scattering (IINS) is well suited to the characterization of industrial catalysts kind materials of catalytic relevance such as supports or cokes. As a consequence of the comparatively large scattering cross section of the hydrogen nucleus, the focus of IINS experiments is usually the proton dynamics of materials. Depending on the location of hydrogen-containing entities, the technique call be used as a surface science or as a bulk technique. The high penetrating power of neutrons in matter permits the investigation of catalyst samples with masses in the range of 10-150g, which tire sealed in aluminum or stainless-steel cars. This procedure allows the investigation of catalysts under reaction conditions with realistic gas pressures. Practical applications of this technique in the chemical industry and academia are presented in this review. The examples include investigations of adsorbed species such as dihydrogen, thiophene, and ammonia and surface species that were detected in the synthesis of amines, in the epoxidation of propene, and in the non-oxidative coupling of methane. Poisoning of a palladium hydrogenation catalyst was traced back to the presence of stable methyl groups in its topmost atomic layers. In this case, the adsorption of aromatic reactants was hampered but not the absorption of atomic hydrogen in the interior of the palladium particles. IINS was also used to characterize the site occupation of atomic hydrogen on platinum nanoparticles supported on carbon black.