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Author: Zahmakiran, MehmetPublication Index: PubMed

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    Article
    Citation - WoS: 24
    Citation - Scopus: 24
    Complete Dehydrogenation of Hydrazine Borane on Manganese Oxide Nanorod-Supported Ni@ir Core-Shell Nanoparticles
    (Amer Chemical Soc, 2020) Yurderi, Mehmet; Top, Tuba; Bulut, Ahmet; Kanberoglu, Gulsah Saydan; Kaya, Murat; Zahmakiran, Mehmet
    Hydrazine borane (HB; N2H4BH3) has been considered to be one of the most promising solid chemical hydrogen storage materials owing to its high hydrogen capacity and stability under ambient conditions. Despite that, the high purity of hydrogen production from the complete dehydrogenation of HB stands as a major problem that needs to be solved for the convenient use of HB in on-demand hydrogen production systems. In this study, we describe the development of a new catalytic material comprised of bimetallic Ni@Ir core-shell nanoparticles (NPs) supported on OMS-2-type manganese oxide octahedral molecular sieve nanorods (Ni@Ir/OMS-2), which can reproducibly be prepared by following a synthesis protocol including (i) the oleylamine-mediated preparation of colloidal Ni@Ir NPs and (ii) wet impregnation of these ex situ synthesized Ni@Ir NPs onto the OMS-2 surface. The characterization of Ni@Ir/OMS-2 has been done by using various spectroscopic and visualization techniques, and their results have revealed the formation of well-dispersed Ni@Ir core-shell NPs on the surface of OMS-2. The catalytic employment of Ni@Ir/OMS-2 in the dehydrogenation of HB showed that Ni-0.22@Ir-0.78/OMS-2 exhibited high dehydrogenation selectivity (>99%) at complete conversion with a turnover frequency (TOF) value of 2590 h(-1) at 323 K, which is the highest activity value among all reported catalysts for the complete dehydrogenation of HB. Furthermore, the Ni-0.22@Ir-0.78/OMS-2 catalyst enables facile recovery and high stability against agglomeration and leaching, which make it a reusable catalyst in the complete dehydrogenation of HB. The studies reported herein also include the collection of wealthy kinetic data to determine the activation parameters for Ni-0.22@Ir-0.78/OMS-2-catalyzed dehydrogenation of HB.
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    Article
    Citation - WoS: 3
    Citation - Scopus: 3
    Comparative Performance Study of Acidic Pumice and Basic Pumice Inclusions for Acrylonitrile-Butadiene Composite Filaments
    (Mary Ann Liebert, inc, 2024) Tayfun, Umit; Tirkes, Seha; Dogan, Mehmet; Tirkes, Suha; Zahmakiran, Mehmet
    This study aims to evaluate the effective use of porous pumice powder as an additive in acrylonitrile-butadiene-styrene (ABS)-based composite materials. The influence of pumice addition on mechanical, thermomechanical, thermal, and physical properties of ABS filaments was reported. Two types of pumice, namely acidic pumice (AP) and basic pumice (BP), were melt compounded with ABS at loading levels of 5%, 10%, 15%, and 20% by weight using the melt extrusion preparation method. Composites were shaped into dog bone test specimens by the injection molding process. The physical properties of pumice powders were investigated by particle size analysis and X-ray spectroscopy techniques. Mechanical, thermomechanical, thermal, melt flow, and morphological behaviors of ABS/AP and ABS/BP composite filaments were proposed. According to test results, pumice addition led to an increase in the mechanical response of ABS up to a filling ratio of 10%. Further inclusion of pumice caused sharp reduction due to the possible agglomeration of pumice particles. Composites filled with AP yielded remarkably higher mechanical performance in terms of tensile, impact, and hardness strength compared with BP-loaded composites. According to thermal analyses, ABS exhibited higher thermal stability after incorporation of AP and BP. Pumice addition also resulted in raising the glass transition temperature of ABS. Melt flow index (MFI) findings revealed that addition of two types of pumice led to an opposite trend in the melt flow behavior of ABS filaments. Homogeneous dispersion of pumice particles into the ABS matrix when adding low amounts, as well as reduction in dispersion homogeneity with high amounts, of AP and BP was confirmed by scanning electron microscopy (SEM) micrographs.
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    Article
    Citation - WoS: 80
    Citation - Scopus: 82
    Amine Grafted Silica Supported Craupd Alloy Nanoparticles: Superb Heterogeneous Catalysts for the Room Temperature Dehydrogenation of Formic Acid
    (Royal Soc Chemistry, 2015) Yurderi, Mehmet; Bulut, Ahmet; Caner, Nurdan; Celebi, Metin; Kaya, Murat; Zahmakiran, Mehmet
    Herein we show that a previously unappreciated combination of CrAuPd alloy nanoparticles and amine-grafted silica support facilitates the liberation of CO-free H-2 from dehydrogenation of formic acid with record activity in the absence of any additives at room temperature. Furthermore, their excellent catalytic stability makes them isolable and reusable heterogeneous catalysts in the formic acid dehydrogenation.
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    Article
    Citation - WoS: 103
    Citation - Scopus: 108
    Copper(0) Nanoparticles Supported on Silica-Coated Cobalt Ferrite Magnetic Particles: Cost Effective Catalyst in the Hydrolysis of Ammonia-Borane With an Exceptional Reusability Performance
    (Amer Chemical Soc, 2012) Kaya, Murat; Zahmakiran, Mehmet; Ozkar, Saim; Volkan, Murvet
    Herein we report the development of a new and cost-effective nanocomposite catalyst for the hydrolysis of ammonia-borane (NH3BH3), which is considered to be one of the most promising solid hydrogen carriers because of its high gravimetric hydrogen storage capacity (19.6% wt) and low molecular weight. The new catalyst system consisting of copper nanoparticles supported on magnetic SiO2/CoFe2O4 particles was reproducibly prepared by wet-impregnation of Cu(II) ions on SiO2/CoFe2O4 followed by in situ reduction of the Cu(II) ions on the surface of magnetic support during the hydrolysis of NH3BH3 and characterized by ICP-MS, XRD, XPS, TEM, HR-TEM and N-2 adsorption-desorption technique. Copper nanoparticles supported on silica coated cobalt(II) ferrite SiO2/CoFe2O4 (CuNPs@SCF) act as highly active catalyst in the hydrolysis of ammonia-borane, providing an initial turnover frequency of TOF = 2400 h(-1) at room temperature, which is not only higher than all the non-noble metal catalysts but also higher than the majority of the noble metal based homogeneous and heterogeneous catalysts employed in the same reaction.. More importantly, they were easily recovered by using a permanent magnet in the reactor wall and reused for up, to 10 recycles without losing their inherent catalytic activity significantly, which demonstrates the exceptional reusability of the CuNPs@SCF catalyst.