Katalysatoren für die Sonnenenergie

Die Entwicklung der künstlichen Photosynthese und somit die mehr oder minder direkte Nutzung der Sonnenenergie ist seit Jahren ein zentrales Thema. Wie kann man Sonnenenergie billiger und besser zugänglich machen? Konkrete Empfehlungen für die zukünftige Forschung sprechen Wissenschaftler nach dem ersten Chemical Sciences and Society Symposium (CS3) zur Nutzung von Sonnenlicht aus.     

Ein Beitrag über Katalysatoren für die Aromatisierung von Ethylen

A Contribution to Catalysts for the Aromatizing of Ethylene A series of monometallic, bimetallic, and trimetallic catalysts (with alumina as carrier) has been tested in the aromatizing of ethylene. The results are correlated with the composition and the metal dispersion of the catalysts. The catalytic activity is compared with the behaviour of the respective catalysts in other hydrocarbon reactions.     

Schwermetallausgetauschte Zeolithe als Katalysatoren für die Selektivoxidation

Transition Metal Zeolites as Catalysts for the Partial Oxidation of Methanol Zeolites containing cations of the 4th period of the periodical system from Ti to Cu have been prepared by ion exchange of a NaY zeolite in aqueous solutions. Structural and surface chemical properties of the zeolites were characterized by adsorption, DTA, thermogastitrimetry, x-ray, ESR, IR, and UV-V is spectroscopy. It could be shown that both localization and coordination state of transition metal ions is fairly different and depends on the thermal treatment of the zeolites. By exchanging sodium ions the acidic properties as well as the ability of the zeolites to interact with H₂O or CO₂ is changed and depends on the kind of transition metal ion. VO and Cr exchanged zeolites proved to be selective catalysts for the oxidative dehydrogenation of methanol to formaldehyde with a maximum selectivity of 70%. It is concluded that in contrast to oxides where a redox mechanism is assumed the reaction on zeolites occurs via an associative mechanism.