Colloidal zeolites as host matrix for copper nanoclusters

Nanosized zeolites stabilized in water suspensions are used as host matrix for the stabilization of copper clusters. The metal clusters are formed by radiolytic reduction of copper-containing large pore zeolites with FAU-(three-dimensional channels) and LTL-(one-dimensional channels) type structures in colloidal form. A selective stabilization of different metal species in the zeolite host matrix is demonstrated depending on the irradiation conditions, type of framework architecture, and copper content in the zeolite. The formation process of different species, that is, Cu-0 or/ and Cu-I, within FAU and LTL zeolites was followed by UV-vis spectroscopy during the entire irradiation process. The transparency of the irradiated colloidal zeolite suspensions allows the absorption measurements to be carried out with low scattering from the zeolite particles having a size of about 50 nm. The use of nanosized crystals stabilized in water suspensions led to the formation of homogeneously distributed copper species all over the zeolite particles and not only on their surface.