S. Akbayrak

Publications (2)7.25 Total impact

• Source

  Available from: Saim Özkar

  Article: Zeolite framework stabilized nickel(0) nanoparticles: Active and long-lived catalyst for hydrogen generation from the hydrolysis of ammonia-borane and sodium borohydride

  M. Zahmakıran, T. Ayvalı, S. Akbayrak, S. Çalışkan, D. Çelik, S. Özkar
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  ABSTRACT: Among the hydrogen storage materials, ammonia-borane and sodium borohydride appear to be promising candidates as they can release hydrogen on hydrolysis in aqueous solution under mild conditions. Here, we report the development of a cost-effective and highly active nickel(0) nanoparticles catalyst for the hydrolysis of ammonia-borane and sodium borohydride. Nickel(0) nanoparticles confined in zeolite framework were prepared by using our previously established procedure and characterized by ICP-OES, XRD, TEM, HR-TEM, SEM, EDX, XPS, Raman spectroscopy and N(2) adsorption-desorption technique. All the results show that nickel(0) nanoparticles are formed within the framework of zeolite-Y. Nickel(0) nanoparticles confined in zeolite framework are highly active catalyst in the hydrolytic dehydrogenations of sodium borohydride and ammonia-borane. This catalyst is isolable, bottleable, redispersible and reusable. The report also includes the detailed kinetic study of the catalytic hydrolysis of both substrates, ammonia-borane and sodium borohydride depending on the catalyst concentration, substrate concentration, and temperature.
  Catalysis Today 01/2011; 170:76. · 3.41 Impact Factor
• Source

  Available from: Saim Özkar

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

  M. Zahmakıran, S. Akbayrak, S. Özkar
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  ABSTRACT: 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 Os(3+) 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.
  Dalton Transactions 01/2010; 39:7521. · 3.84 Impact Factor