Browsing by Author "Zahmakiran, M."

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Bimetallic Pdxni1-X and Pdxco1-X Nanoparticles Supported on K-Oms Highly Active, Environmentally Friendly and Reusable Nanocatalysts for the Suzuki–miyaura Cross-Coupling Reactions in Water
(John Wiley and Sons Ltd, 2021) Durap, F.; Gülen, Y.; Abay, A.; Bulut, A.; Yurderi, M.; Aydemir, M.; Zahmakiran, M.
Addressed herein is the catalysis of bimetallic PdxNi1-x and PdxCo1-x nanoparticles (NPs) supported on a cryptomelane-type manganese oxide (K-OMS-2) solid for the Suzuki–Miyaura cross-couplings of phenylboronic acid with various aryl halides. Bimetallic PdxNi1-x and PdxCo1-x NPs were prepared by using a conventional one-step impregnation–reduction method. Among these catalysts with different compositions of Ni and Pd or Co and Pd, the Pd0.2Ni0.8 and Pd0.2Co0.8 catalysts showed the highest activity in the Suzuki–Miyaura cross-couplings of various aryl halides including iodides, bromides, and even chlorides with phenylboronic acid in ambient air and water under reflux conditions. The Suzuki–Miyaura cross-coupling reaction proceeded efficiently in the presence of Pd0.2Ni0.8@K-OMS-2 and Pd0.2Co0.8@K-OMS-2 NPs under the optimized conditions in water. Pd0.2Ni0.8@K-OMS-2 and Pd0.2Co0.8@K-OMS-2 NPs provided high conversions up to 98% and 99% and turnover frequencies of 11,760 and 11,880 h−1 in the cross-coupling of phenylboronic acid with 1-bromo-4-nitrobenzene. More importantly, these new supported Pd0.2Ni0.8@K-OMS-2 and Pd0.2Co0.8@K-OMS-2 NPs were found to be highly durable nanocatalyst throughout the reusability experiments, and they maintain almost their inherent activity after 10th and 5th catalytic cycle, respectively. Bimetallic Pd0.2Ni0.8@K-OMS-2 and Pd0.2Co0.8@K-OMS-2 NPs were characterized by Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), scanning electron microscopy with energy dispersive X-ray (SEM-EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and ICAPQ inductively coupled plasma mass spectroscopy (ICP-MS) analyses. © 2020 John Wiley & Sons, Ltd.
Effect of Silver Encapsulation on the Local Structure of Titanosilicate Ets-10
(2012) Galioǧlu, S.; Zahmakiran, M.; Eren Kalay, Y.; Özkar, S.; Akata, B.
Silver(0) nanoparticles stabilized by titanosilicate (ETS-10) framework were synthesized by following a simple two step procedure involving the incorporation of silver(I) (Ag +) ions into ETS-10 matrix via ion-exchange with extra framework Na + and K + cations followed by their reduction with sodium borohydride (NaBH 4) in aqueous medium all at room temperature. Silver(0) nanoparticles dispersed in the ETS-10 matrix were collected as gray powders and characterized by using advanced analytical methods including ICP-OES, P-XRD, XPS, FE-SEM, TEM, HR-TEM, DR-UV-vis, Raman spectroscopies and N 2 adsorption-desorption technique. Overall result shows the formation of silver(0) nanoparticles dispersed within the framework of ETS-10 without causing alteration in ETS-10 lattice and mesopore formation. The changes in the local titanate (TiO 3 2-) structure of ETS-10 resulting from the incorporation of silver(I) ions and formation of silver(0) nanoparticles within the titanosilicate (xTiO 2 (1 - x)SiO 2) framework were extensively studied on silver(I)-exchanged and silver(0) nanoparticles containing samples, separately. Although maintaining of structural integrity of host material had been monitored for silver(I)-ETS-10, detailed Raman analyses of silver(0)-ETS-10 samples showed significant changes in the titanate quantum wires of ETS-10 framework depending on the silver loading. Total collapse of these units was observed in the silver(0)-ETS-10 samples with high silver loading (15 wt.% silver(I)). Moreover, the catalytic application of silver(0)-ETS-10 was demonstrated in the aerobic oxidation of diphenyl carbinol to benzophenone, which showed that silver(0)-ETS-10 is a highly active and selective catalyst in this reaction. Additionally, they were found to be highly stable catalyst for this transformation. © 2012 Elsevier Inc. All rights reserved.
Liquid Phase Chemical Hydrogen Storage: From Recent Developments To Future Objectives
(Elsevier, 2018) Ertas, I.E.; Yurderi, M.; Bulut, A.; Agirtas, M.S.; Zahmakiran, M.
The hydrolytic dehydrogenation of aqueous boron-nitrogen (B-N)-based compounds such as NaBH4 and NH3BH3 has received much attention, and because of their high hydrogen content they have been shown to be promising hydrogen carriers for storage and transportation. Formic acid (HCOOH), a major product formed in biomass processing, has been intensely investigated for liquid phase chemical hydrogen storage owing to its high energy density, stability, and nontoxicity. In this chapter, we focus on advances in research on hydrogen storage and release of these liquid phase hydrogen storage materials. Main advantages and drawbacks of these systems in liquid phase hydrogen storage are also discussed. © 2018 Elsevier Inc. All rights reserved.
Nanocatalytic Architecture for the Selective Dehydrogenation of Formic Acid
(wiley, 2021) Baguc, I.B.; Kanberoglu, G.S.; Yurderi, M.; Bulut, A.; Celebi, M.; Kaya, M.; Zahmakiran, M.
Formic acid (HCOOH) is a main by-product formed through many biomass processes and has recently been proposed as one of the most promising liquid organic hydrogen carrier material in the chemical hydrogen storage for the fuel cell applications. However, efficient hydrogen (H2) generation through catalytic formic acid dehydrogenation under mild thermodynamic conditions constitutes a major challenge because poisoning of active metal center exists in catalytic systems with carbon monoxide (CO) formed as an intermediate. In this chapter, we focus on the research advances on the formic acid dehydrogenation in the presence of different nanocatalysts including monometallic, bimetallic, and trimetallic nanoparticles in the form of alloy, core@shell, and physical mixture. The main advantages and drawbacks of these systems are presented by comparing their catalytic performances depending on additives, solvents, and temperature parameters. Additionally, the morphology, structure, and composition of these nanocatalysts as well as their synthesis protocols are discussed, and new synthesis strategies are proposed to enhance the catalytic performance of nanocatalysts in the formic acid dehydrogenation. © 2021 WILEY-VCH GmbH, Boschstr. 12, 69469 Weinheim, Germany.
Preparation of Metal Nanoparticles Stabilized by the Framework of Porous Materials
(Royal Society of Chemistry, 2013) Zahmakiran, M.; Özkar, S.