Narrow Results

The formation of gold nanoparticles in mordenites has been studied by the methods of FTIR spectroscopy of adsorbed CO and diffuse reflectance UV-visible spectroscopy. Different states of ionic and metallic gold were detected in the zeolite cavities and on the external surface of the zeolite – Au⁺ and Au³⁺ ions, charged clusters Au_n^δ+, and neutral nanoparticles Au_m. The relative amount of these states depends on the method of sample preparation, type of redox treatment and the SiO₂/Al₂O₃ molar ratio.

The present work is devoted to the study of some properties (size, electronic state, redox properties, interaction with matrix) of gold clusters and nanosized particles in Na-Y zeolite modified by iron. Two methods of iron introduction were applied: wet-impregnation and ion-exchange, which result in different structure and reducibility of iron species. Aggregation of iron species and their probable dissolution during gold deposition in samples prepared by wet-impregnation permits to form new Au, Fe and Au-Fe species in contrast to samples prepared by ion-exchange. The strong interaction of Au with Fe species in Au/Fe-imp/NaY changes noticeably a behavior of gold nanoparticles under heating.