gamma-Alumina-supported [60]fullerene catalysts: Synthesis, properties and applications in the photooxidation of alkenes

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gamma-Alumina-supported [60]fullerene catalysts: Synthesis, properties and applications in the photooxidation of alkenes (EN)

Tzirakis, M. D. (EN)

Πανεπιστήμιο Ιωαννίνων. Σχολή Θετικών Επιστημών. Τμήμα Χημείας (EL)
Tzirakis, M. D. (EN)

Immobilization of [60]fullerene onto gamma-Al(2)O(3) surface provides new heterogeneous photocatalysts for the oxidation of organic Compounds under oxygen atmosphere. These catalysts have been prepared by simple or Successive incipient wetness impregnation (using an organic solvent) followed by air-heating at 180 degrees C. In the C(60)/Al(2)O(3) system. C(60) loading was varied in the range of 1-4% (w/w). Several experimental techniques including BET. XRD, DRS, TGA, microelectrophoresis, photoluminescence and kinetic extraction, have been used to characterize these catalytic materials. It was found that the quite high surface exposed by the supported C(60) increases with the amount of the supported C(60), while the dispersion of the supported C(60) decreases. The quite stable supported [60]fullerene phase is comprised from C(60) clusters, small and large aggregates. This non-uniform size distribution is reflected to a non-uniform distribution concerning the 'supported phase-support' interactions. These interactions decrease with the amount of the supported C(60). The photocatalysts prepared may be safely used Lip to 200 degrees C. Above this temperature the supported C(60) is sublimated/combusted in air. The photocatalytic activity of the so-obtained catalytic systems has been evaluated in terms of substrate conversion in the singlet oxygen 'ene' reaction of alkenes. The photooxygenation of 2-methyl-2-heptene has been examined as a probe reaction. It was round that the catalytic activity increases with the increasing amount of the supported C(60) up to the value of 3% (w/w) and then decreases. The intrinsic activity expressed as TON or TOF decreased monotonically with C(60). In all cases, however. the photocatalytic activity of the Al(2)O(3)-supported C(60) catalysts was substantially increased compared to the unsupported C(60) precursor, exhibiting quantitative conversion yields after short reaction times. The catalytic behavior was attributed to the aforementioned opposite trends which follow the surface exposed by the supported C(60) on one hand and the 'supported C(60)-support' interactions and the C(60) dispersion on the other hand. The easy separation of these solid catalysts from the reaction mixture, the high activity and stability as well as the retained activity in subsequent catalytic cycles. make these supported catalysts suitable for a small-scale synthesis. (C) 2009 Elsevier B.V. All rights reserved. (EN)

c(60) (EN)

Journal of Molecular Catalysis a-Chemical (EN)



Elsevier (EN)

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