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Publisher: Elsevier Science BvSubject: Alloy

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    Article
    Citation - WoS: 51
    Citation - Scopus: 54
    Atomic Layer Deposition-sio2 Layers Protected Pdconi Nanoparticles Supported on Tio2 Nanopowders: Exceptionally Stable Nanocatalyst for the Dehydrogenation of Formic Acid
    (Elsevier Science Bv, 2017) Caner, Nurdan; Bulut, Ahmet; Yurderi, Mehmet; Ertas, Ilknur Efecan; Kivrak, Hilal; Kaya, Murat; Zahmakiran, Mehmet
    TiO2 nanopowders supported trimetallic PdCoNi alloy nanoparticles were simply and reproducibly prepared by wet-impregnation followed by simultaneous reduction method, then to enhance their stability against to sintering and leaching atomic layer deposition (ALD) technique was utilized to grow SiO2 layers amongst these surface bound PdCoNi alloy nanoparticles (PdCoNi/TiO2-ALD-SiO2). These new nanomaterials are characterized by the combination of complimentary techniques and sum of their results exhibited that the formation of ALD-SiO2 layers protected well-dispersed and highly crystalline PdCoNi alloy nanoparticles (ca. 3.52 nm) supported on TiO2 nanopowders. The catalytic performance of the resulting PdCoNi/TiO2-ALD-SiO2 in terms of activity, selectivity and stability was investigated in the dehydrogenation of aqueous formic acid (HCOOH), which has recently been suggested as a promising hydrogen storage material with a 4.4 wt% hydrogen capacity, solution under mild conditions. The results collected from our systematic studies revealed that PdCoNi/TiO2-ALD-SiO2 nanomaterial can act as highly active and selective nanocatalyst in the formic acid dehydrogenation at room temperature by providing an initial turnover frequency (TOF) value of 207 mol H-2/mol metal;: h and >99% of dehydrogenation selectivity at almost complete conversion. More importantly, the catalytic reusability experiments separately carried out with PdCoNi/TiO2-ALD-SiO2 and PdCoNi/TiO2 nanocatalysts in the dehydrogenation of formic acid under more forcing conditions pointed out that PdCoNi/TiO2-ALD-SiO2 nanocatalyst displays unprecedented catalytic stability against to leaching and sintering throughout the reusability experiments it retains almost its inherent activity, selectivity and conversion even at 20th reuse, whereas analogous PdCoNi/TiO2 completely lost its catalytic performance. (C) 2017 Elsevier B.V. All rights reserved.
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    Article
    Citation - WoS: 148
    Citation - Scopus: 152
    Carbon Supported Trimetallic Pdniag Nanoparticles as Highly Active, Selective and Reusable Catalyst in the Formic Acid Decomposition
    (Elsevier Science Bv, 2014) Yurderi, Mehmet; Bulut, Ahmet; Zahmakiran, Mehmet; Kaya, Murat
    Trimetallic PdNiAg nanoparticles supported on activated carbon were simply and reproducibly prepared by wet-impregnation followed by simultaneous reduction method without using any stabilizer at room temperature. The characterization of the resulting material was done by the combination of complimentary techniques and the sum of their results shows that the formation of well-dispersed 5.6 +/- 2.2 nm PdNiAg nanoparticles in alloy form on the surface of activated carbon. These carbon supported PdNiAg nanoparticles were employed as heterogeneous catalyst in the catalytic decomposition of formic acid, which has great potential as a safe and convenient hydrogen carrier for fuel cells, under mild conditions. It was found that PdNiAg/C can catalyze the dehydrogenation of formic acid with high selectivity (similar to 100%) and activity (TOF = 85 h(-1)) at 50 degrees C. More importantly, the exceptional stability of PdNiAg nanoparticles against to agglomeration, leaching and CO poisoning make PdNiAg/C reusable catalyst in the formic acid dehydrogenation. PdNiAg/C catalyst retains almost its inherent activity (>94%) even at 5th reuse in the dehydrogenation of formic acid with high selectivity (similar to 100%) at complete conversion. The work reported here also includes the compilation of kinetic data for PdNiAg/C catalyzed dehydrogenation of formic acid depending on catalyst [PdNiAg], substrate [HCOOH], promoter [HCOONa] concentrations and temperature to determine the rate expression and the activation parameters (Ea, Delta H-#, and Delta S-#) of the catalytic reaction. (C) 2014 Elsevier B.V. All rights reserved.