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Öğe Ceria supported copper(0) nanoparticles as efficient and cost-effective catalyst for the dehydrogenation of dimethylamine borane(Elsevier, 2017) Tanyıldızı, Seda; Morkan, İzzet; Özkar, SaimThis work aims the preparation and catalytic use of copper(0) nanoparticles supported on ceria as catalyst in dehydrogenation of dimethylamine borane. They were in situ generated from the reduction of Cu2+/CeO2 during the catalytic dehydrogenation of dimethylamine borane in toluene. The results of characterization by using XRD, SEM, SEM-EDX, TEM, UV-vis, XPS techniques reveal the formation of highly dispersed copper(0) nanoparticles with average particle size of 3.1 +/- 0.8 nm on the surface of ceria nanopowders. Cu(0)/CeO2 nanoparticles are active catalysts releasing 1.0 equiv. H-2 per mole of dimethylamine borane. The catalytic activity of Cu(0)/CeO2 shows variation with the copper loading of ceria and the highest catalytic activity is achieved by using Cu(0)/CeO2 sample with a copper loading of 4.0 wt.% Cu which provides a turnover frequency value of 40 h(-1) and 225 turnovers in hydrogen generation from dimethylamine borane at 60.0 +/- 0.5 degrees C. The equation for the catalytic reaction was established by determining all the products. We performed the kinetic studies for understanding the catalytic dehydrogenation of dimethylamine borane in molecular level. The results of kinetic study reveal that the reaction is first order with respect to catalyst concentration. The work reported here also includes the kinetic study depending on the temperature to determine the activation energy (E-2 = 76 +/- 2 kJ/mol). (C) 2017 Elsevier B.V. All rights reserved.Öğe Computational study of intermolecular interactions between L-cysteine and 2-mercaptopyrimidine using DFT, QTAIM, and NBO methods(Amer Chemical Soc, 2016) Morkan, İzzet; Morkan, Ayşe; Yazıcı, Hasan; Gül, Esra; Tanyıldızı, Seda[No Abstract Available]Öğe Cu-0/TiO2 nanoparticles as active catalyst for H-2 production from dimethylamine borane(Wiley-V C H Verlag GMBH, 2021) Karacan, Yeşim Öztürk; Karaboğa, Seda; Morkan, İzzetThe study reports the preparation and characterization of low cost Cu-0 nanoparticles obtained from reduction of impregnated Cu2+ ions on the surface of titanium(IV) oxide (TiO2) during hydrogen releasing from dimethylamine borane (DMAB). Cu-0/TiO2 nanoparticles act as active catalyst with a turnover frequency 59.9 h(-1) in H-2 releasing of dimethylamine borane at 60.0 +/- 0.5 degrees C. The obtained catalysts, Cu-0/TiO2 NPs, were isolated from reaction medium and characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Ultraviolet-visible spectroscopy (UV vis.) and X-ray photoelectron spectroscopy (XPS) techniques. Cu-0/TiO2 nanoparticles with different metal loadings (4.0-8.0 % Cu wt.) were prepared and tested as catalyst in dehydrogenation of dimethylamine borane at 60.0 +/- 0.5 degrees C. All results reveal that Cu-0 NPs dispersed on the surface of titania were found as 2.96 +/- 0.83 nm. The highest catalytic activity was achieved for Cu-0/TiO2 NPs, 0.6 % Cu wt. with a turnover frequency 59.9 h(-1) in H-2 releasing of dimethylamine borane at 60.0 +/- 0.5 degrees C. The work reported here also includes the kinetic study depending on the temperature.Öğe Effect of magnesium source on the fabrication of kotoite Mg3B2O6 ceramic(Wiley, 2018) Morkan, Ayşe; Gül, Esra; Morkan, İzzet; Kahveci, GüldenThe effect of magnesium source on the fabrication of kotoite, Mg3B2O6, ceramic has been investigated by high temperature solid-state reaction route based on the calcination of different magnesium sources, containing magnesium oxide, magnesium carbonate, magnesium sulfate, and magnesium nitrate with boric acid. The X-ray powder diffraction results showed that single-phase kotoite, Mg3B2O6, was synthesized using MgNO3.6H(2)O and 5 wt.% excess of H3BO3 powders as starting materials at 900 degrees C for 48hours. Mg3B2O6 obtained, is well crystallized, in orhorhombic crystal structure with lattice parameters of a=5.399(9), b=8.424(6), and c=4.506(5) angstrom. Jana2006 refinement of this product shows excellent fit of the experimental data with software data, GOF= 1.33. The crystallite size of the product was calculated as 40.50nm using Debye-Scherrer's equation. The existence of BO3 triangles were detected by FTIR measurements of Mg3B2O6. The thermal properties were studied in the temperature range of 20 degrees C to 1400 degrees C by TG/DTA. The results showed that thermal stability of Mg3B2O6 is detected about 1380 degrees C. Scanning electron microscopy was employed for observation of microstructure. The microstucture of obtained ceramic samples strongly depended on the magnesium source on the fabrication of Mg3B2O6 ceramic.Öğe H2(g) production from dimethylamine borane by Cu0/WO3 NPs catalyst(Scientific and Technological Research Council Turkey, 2023) Al-Hameedaw, Doaa; Karaboğa, Seda; Morkan, İzzetCu0 NPs supported on tungsten (VI) oxide (WO3) were in situ generated from the reduction of Cu2+ ions during dehydrogenation of dimethylamine borane (DMAB). The Cu0/WO3 NPs displayed tangible catalytic activity in H2 (g) releasing reaction and they were identified by using advanced techniques. Cu0/WO3 NPs were found as active catalyst providing one equiv. H2(g) per mole of DMAB. The results from TEM images display the formation of Cu0 NPs with an average particle size of 4.6 ± 1.0 nm on the surface of WO3. Moreover, Cu0/WO3 NPs with various metal loadings were prepared and tested as catalyst in dehydrogenation reaction to find the optimum metal loading on WO3 support. The highest H2 generation rate was achieved for 4.0% wt. Cu0/WO3 catalyst with TOF value of 39 h?1 in the reaction conditions. Additionally, effect of various catalyst concentration and temperature is discussed on the reaction kinetics for reaction catalyzed by Cu0/WO3 NPs.Öğe Hydrogenation of ketones using ammonia borane and dimethylamine borane as a hydrogen donor(Amer Chemical Soc, 2016) Tanyıldızı, Seda; Morkan, İzzet; Özkar, Saim[No Abstract Available]Öğe Intermediate products in solid-state reactions of gadolinium oxide and ammonium dihydrogen phosphate(Wiley-V C H Verlag Gmbh, 2007) Morkan, Ayşe Üztetik; Morkan, İzzet; Demirözü, Sevim Şenol; Güler, HikmetThe solid-state reactions of Gd2O3 with NH4H2PO4 using various molar ratios (3:6, 2:8, 1:6 and 1:8) of the reactants were investigated at different temperatures (350-1100 degrees C) to observe the intermediate compounds. Analysis of the X-ray powder diffraction patterns of the products obtained at 350 degrees C; for the compositions of 2:8, 1:6 and 1:8 molar ratios revealed the formation of a new compound, NH4GdHP3O10 which was reported previously for Nd, Ho and Er. At higher temperatures, gadolinium tripolyphosphate was obtained for all of the molar ratios. On the other hand, the IR data of the products also confirmed the proposed reaction pathways. (c) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.Öğe Nanotitania supported ruthenium(0) nanoparticles as active catalyst for releasing hydrogen from dimethylamine borane(Pergamon-Elsevier Science Ltd, 2024) Al-Areedhee, Ahmed Hammoodi Yousif; Karaboğa, Seda; Morkan, İzzet ; Özkar, SaimWe reports the ex situ preparation of nanotitania supported ruthenium(0) nanoparticles (NPs) and their catalytic testing in dehydrogenation of dimethylamine borane (DMAB) in toluene solvent. Ru0/TiO2 NPs are prepared following a 2-step process: Ru3+ ions are first impregnated from the aqueous solution on titania nanopowder and then, reduced by aqueous solution of sodium borohydride. The prepared Ru0/TiO2 NPs are dried, bottled under inert N2 gas atmosphere, and used for characterization by XRD (X-ray powder diffraction), TEM (transmission electron microscopy), ICP-OES (inductively coupled plasma optical emission spectroscopy) and XPS (X-ray photoelectron spectroscopy). Ru0/TiO2 NPs with various Ru loadings are tested as catalysts in hydrogen generation from DMAB and the Ru0/TiO2 (0.48% wt. Ru) with an average diameter of 6.7 +/- 1.3 nm is found to have the highest initial turnover frequency value of 1700 h-1 for the release of 1.0 mol H2 per mole of DMAB at 60 degrees C. Results of the recyclability test indicate quite high durability of Ru0/TiO2 NPs in dehydrogenation of DMAB.(c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.Öğe Nanotitania-supported rhodium(0) nanoparticles: superb catalyst in dehydrogenation of dimethylamine borane(Wiley-V C H Verlag Gmbh, 2017) Tanyıldızı, Seda; Morkan, İzzet; Özkar, SaimRhodium(0) nanoparticles, in situ formed from the reduction of rhodium(II) octanoate in toluene solution, are active catalyst in dehydrogenation of dimethylamine borane, however not very stable. When the same nanoparticle formation reaction is performed in the presence of nanotitania it yields the supported rhodium(0) nanoparticles (Rh(0)/nanoTiO(2)) with an average size of 3.17 +/- 0.52 nm, which can be isolated and characterized by a combination of analytical techniques including inductively coupled plasma optical emission spectrometry (ICP-OES), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray (EDX), Brunauer-Emmett-Teller (BET) surface area measurement. Rh(0)/nanoTiO(2) is highly active and long lived catalyst providing 9700 turnovers in releasing 1 equivalent H2 from dimethylamine borane over 27 h before deactivation and a record initial turnover frequency (TOF) value of 2900 h(-1) in H-2 generation at 60.0 +/- 0.5 degrees C, which is the highest TOF value ever reported for dehydrogenation of dimethylamine borane using homogeneous or heterogeneous catalyst. Rh(0)/nanoTiO(2) is also quite reusable catalyst preserving 57% of the initial catalytic activity even after the fourth run of dehydrogenation reaction. This report also includes the results of kinetic study on the catalytic dehydrogenation of dimethylamine borane depending on the temperature and catalyst concentration.Öğe Preparation and characterization of new borophosphates of PrB(PO4)2 and TbB(PO4)2(Amer Chemical Soc, 2015) Morkan, Ayşe; Morkan, İzzet; Kahveci, Gülden; Gül, EsraÖğe Rhodium(0) nanoparticles supported on nanotitania as highly active catalyst in hydrogen generation from the hydrolysis of ammonia borane(Royal Soc Chemistry, 2014) Akbayrak, Serdar; Gençtürk, Serap; Morkan, İzzet; Özkar, SaimRhodium(0) nanoparticles supported on the surface of titanium dioxide (Rh(0)@TiO2) were in situ generated from the reduction of rhodium(III) ions impregnated on nanotitania during the hydrolysis of ammonia borane. They were isolated from the reaction solution by centrifugation and characterized by a combination of advanced analytical techniques. The results show that (i) highly dispersed rhodium(0) nanoparticles with sizes in the range 1.3-3.8 nm were formed on the surface of titanium dioxide, (ii) Rh(0)@TiO2 shows high catalytic activity in hydrogen generation from the hydrolysis of ammonia borane with a turnover frequency value up to 260 min(-1) at 25.0 +/- 0.1 degrees C, (iii) the results of kinetic studies on the hydrogen generation from the hydrolysis of ammonia borane were also reported including the activation energy of 65.5 +/- 2 kJ mol(-1) for this reaction.Öğe Ruthenium catalyzed dehydrogenation and transfer hydrogenation reactions using dimethylamine borane as a hydrogen storage(Amer Chemical Soc, 2015) Tanyıldızı, Seda; Morkan, İzzet; Özkar, SaimÖğe Ruthenium(0) nanoparticles supported on nanotitania as highly active and reusable catalyst in hydrogen generation from the hydrolysis of ammonia borane(Pergamon-Elsevier Science Ltd, 2014) Akbayrak, Serdar; Tanyıldızı, Seda; Morkan, İzzet; Özkar, SaimRuthenium(0) nanoparticles supported on the surface of titania nanospheres (Ru(0)/TiO2) were in situ generated from the reduction of ruthenium(III) ions impregnated on nanotitania during the hydrolysis of ammonia borane. They were isolated from the reaction solution by centrifugation and characterized by a combination of advanced analytical techniques. The results reveal that highly dispersed ruthenium(0) nanoparticles of size in the range 1.5-3.3 nm were formed on the surface of titania nanospheres. Ru(0)/TiO2 show high catalytic activity in hydrogen generation from the hydrolysis of ammonia borane with a turnover frequency value up to 241 min(-1) at 25.0 +/- 0.1 degrees C. They provide unprecedented catalytic lifetime measured by total turnover number (TTO = 71,500) in hydrogen generation from the hydrolysis of ammonia borane at 25.0 +/- 0.1 degrees C. The report also includes the results of kinetic study on the catalytic hydrolysis of ammonia borane depending on the temperature to determine the activation energy of the reaction (E-a = 70 +/- 2 kJ/mol) and the catalyst concentration to establish the rate law of the reaction. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.Öğe Sol-gel synthesis and characterization of coatings of Mg-Al layered double hydroxides(Mdpi, 2019) Smalenskaite, Aurelija; Kaba, Musa Mohammed; Grigoraviciute-Puroniene, Inga; Mikoliunaite, Lina; Zarkov, Aleksej; Morkan, İzzetIn this study, new synthetic approaches for the preparation of thin films of Mg-Al layered double hydroxides (LDHs) have been developed. The LDHs were fabricated by reconstruction of mixed-metal oxides (MMOs) in deionized water. The MMOs were obtained by calcination of the precursor gels. Thin films of sol-gel-derived Mg-Al LDHs were deposited on silicon and stainless-steel substrates using the dip-coating technique by a single dipping process, and the deposited film was dried before the new layer was added. Each layer in the preparation of the Mg-Al LDH multilayers was separately annealed at 70 degrees C or 300 degrees C in air. Fabricated Mg-Al LDH coatings were characterized by X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM), and atomic force microscopy (AFM). It was discovered that the diffraction lines of Mg3Al LDH thin films are sharper and more intensive in the sample obtained on the silicon substrate, confirming a higher crystallinity of synthesized Mg3Al LDH. However, in both cases the single-phase crystalline Mg-Al LDHs have formed. To enhance the sol-gel processing, the viscosity of the precursor gel was increased by adding polyvinyl alcohol (PVA) solution. The LDH coatings could be used to protect different substrates from corrosion, as catalyst supports, and as drug-delivery systems in medicine.Öğe Solvothermally derived Me-2(H2O)(4)(5SSA)(3)center dot DMF and Me-2(H2O)(4) (4NSA)(2)center dot DMF: Application as Biginelli reaction catalysts(Lietuvos Mokslu Akad Leidykla, 2019) Laurikenas, Andrius; Yalçın, Fatma; Zilinskas, Robertas; Morkan, Ayşe; Zilinskas, Albinas; Morkan, İzzet; Kareiva, AivarasThe solvothermal synthesis between Me(NO3)(x)center dot yH(2)O (me(x+) = Fe3+, Ni2+, M2+, Co2+, Cu2+) and respectively 4-nitrosalycilic (4NSA) and 5-sulfosalicylic (5SSA) acids produced hybrid organic-inorganic compounds composed of me- ions and organic fragments which include three different functional groups, carboxylic, hydroxyl and sulfonic, each coordinated to the Mex+ ions. The phase and chemical composition, microstructure and properties of Me-2(H2O)(4)(5SSA)3 center dot DMF and Me-2(H2O)(4)(4NSA)(2)center dot DMF (DMF - dimethylformamide) hybrid compounds were evaluated and discussed. The synthesised materials were characterised by X-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) and nuclear magnetic resonance (NMR) spectroscopy. The catalytic properties of the obtained compounds were also investigated.Öğe Synthesis and band gap determination of nano nickel borate material co-doped with terbium and manganese(Amer Chemical Soc, 2016) Morkan, Ayşe; Gül, Esra; Morkan, İzzet[No Abstract Available]Öğe Synthesis and characterization of rare earth metal doped magnesium borates(Amer Chemical Soc, 2015) Morkan, Ayşe; Morkan, İzzet; Gül, Esra; Kahveci, GüldenÖğe Synthesis of sodium neodymium diphosphate, NaNdP2O7, and its powder XRD data and IR spectra(Taylor & Francis Ltd, 2005) Uztetik-Morkan, Ayşe; Morkan, İzzet; Özen, Gürkan; Güler, Hikmet; Kızılyallı, MeralNaNdP2O7 was synthesized by the solution reaction of NdCl3 with Na4P2O7 and heated the precipitate at 650 degrees C for 6-7 h. The X-ray powder diffraction data of this compound was indexed in the orthorhombic system with the refined unit-cell-parameters of a = 12.579(7), b = 15.10(l), and c = 16.030(1)angstrom, which were in good agreement with the reported data of NaGdP2O7. It was found that NaLnP(2)O(7) compounds (Ln: La, Eu, Gd, and Y) cannot be synthesized by this method, but NaCeP2O7 has been prepared as an amorphous product. The IR spectra of NaNdP2O7 also agreed with the IR data of NaGdP2O7 with the presence of P2O74- vibrational modes.
