TY - CONF A1 - Radnik, Jörg A1 - Dang, Thi Thuy Hanh A1 - Gatla, Suresh A1 - Ruguwanshi, A1 - Hoell, Armin T1 - Redox properties of Cu ions in molecular sieves N2 - Molecular sieves as materials with defined pores offer new opportunities in the preparation of nanostructured materials for different applications in chemistry, medicine and biology. Typical examples for such materials are zeolites, porous glass, different silicas and active carbon. Introducing transition metal ions in such materials can widen the possibilities of these materials in terms of chemical activity. Especially, the opportunity to tailor the redox properties of the transition metal ions by varying the location of the ion in the sieves is a promising way to obtain catalysts with the desired properties. For this purpose, Cu2+ ions were introduced into a SAPO-5 (silicoaluminaphosphate) by a hydrothermal method and by impregnation. As expected, the different preparation methods led to different locations of the Cu2+ ions: by the hydrothermal method the ions were incorporated in the SAPO-5 framework, by impregnation mononuclear Cu species randomly distributed in the pores of the support or CuO particles were formed depending on the Cu amount. These locations could be determined by Extended X-ray Absorption Fine Structure and Anomalous Small-Angle X-ray Scattering investigations. For investigating the redox properties of the Cu2+ ions the differently prepared sample were treated in Ar and H2 atmosphere until 550°C. X-ray Photoelectron Spectroscopy was performed to study the valence states of Cu after each of such treatment. For a definite determination of the valence states, both Cu 2p and Cu LMM spectra must be recorded. Cu2+ exhibits a clear chemical shift and a typical satellite structure in Cu2p spectra, but between mono- and zerovalent Cu a differentiation is not possible. On the other hand, these two species show a clear shift in the Auger spectra. Whereas in H2 atmosphere in any case metallic Cu was formed, the treatment in Ar showed significant differences between the samples. Cu2+ incorporated in the framework could not be reduced by this treatment. In contrast, the mononuclear Cu2+ species were reduced to stable Cu+. Likewise, the CuO nanoparticles were reduced to the monovalent Cu, but this species can be much more easily reoxidized in air. The consequences for the catalytic properties will be discussed. T2 - ECASIA 2017 CY - Montpellier, France DA - 24.09.2017 KW - Catalysis KW - X-ray photoelectron spectroscopy KW - Nanostructured materials PY - 2017 AN - OPUS4-42323 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -