Osmium(0) nanoclusters stabilized by zeolite framework; highly active catalyst in the aerobic oxidation of alcohols under mild conditions


Zahmakiran M. , Akbayrak S., KODAIRA T., ÖZKAR S.

DALTON TRANSACTIONS, cilt.39, ss.7521-7527, 2010 (SCI İndekslerine Giren Dergi) identifier identifier identifier

  • Cilt numarası: 39 Konu: 32
  • Basım Tarihi: 2010
  • Doi Numarası: 10.1039/c003200j
  • Dergi Adı: DALTON TRANSACTIONS
  • Sayfa Sayıları: ss.7521-7527

Özet

Osmium(0) nanoclusters stabilized by zeolite-Y framework were reproducibly prepared by a simple two step procedure involving the incorporation of osmium(III) canons into the zeolite matrix by ion-exchange, followed by their reduction within the cavities of zeolite with sodium borohydride in aqueous solution all at room temperature. The composition and morphology of osmium(0) nanoclusters stabilized by zeolite framework, as well as the integrity and crystallinity of the host material were investigated by using ICP-OES, XRD, XPS, SEM, TEM, HRTEM. TEM/EDX, mid-IR, far-IR spectroscopes. and N-2-adsorption/desorption technique The results of the multipiong analysis reveal the formation of osmium(0) nanoclusters within the cavities of zeolite-Y without causing alteration in the framework lattice, formation of mesopores. or loss in the crystallinity of the host material More importantly. far-IR studies showed that after the reduction of Os3+ canons by sodium borohydride the Na+ canons reoccupy their authentic canon sites restoring the integrity of zeolite-Y The catalytic activity of osmium(0) nanoclusters stabilized by zeolite framework was tested in the aerobic oxidation of activated. unactivated and heteroatom containing alcohols to carbonyl compounds and was found to provide high activity and selectivity even under mild conditions (80 degrees C and 1 atm O-2 or air) Moreover, they were found to be stable enough to be isolated and bottled as solid material, which can be reused as active catalyst under the identical conditions of the first run