Moessbauer spectroscopy on superparamagnetic nanoparticles used as catalyst supports for the production of fine chemicals

摘要

Temperature and field dependent Moessbauer spectroscopy has been used to characterize silica coated iron oxide nanoparticles with a core size of ～ 10 nm. Covalent attachment of oxodiperoxo molybdenum complexes to the silica surface of these particles yields an organic-inorganic hybrid nanocatalyst which is an active, magnetically separable epoxidation catalyst. Moessbauer spectroscopy identifies superparamagnetic γ-Fe_2O_3 particles, whereas the presence of significant amounts of Fe_3O_4 05 %) can be excluded.