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Öğe AgNi/PC bimetallic and AgNi/PC@Mn trimetallic nanocatalysts for the efficient reduction of 4-nitrophenol(Elsevier, 2024) Erdem, Hikmet Beyza; Cetinkaya, SevilCatalytic efficiency in hydrogenation reactions can be increased due to the stability achieved with nanomaterials prepared by homogeneously immobilizing multiple metal nanoparticles onto porous solid materials. Herein, porous carbon (PC)-supported bimetallic (AgNi/PC) and trimetallic nanoparticles (AgNi/PC@Mn) were developed and evaluated as catalysts in the NaBH4-mediated reduction of 4-nitrophenol to 4-aminophenol. AgNi/ PC@Mn catalysts were synthesized using a two-step synthesis strategy. The highest and excellent catalytic efficiency under ambient conditions was obtained by the trimetallic catalyst. Both catalysts proved to be easily separated from the reaction medium and usable for up to five consecutive cycles without losing their catalytic activity.Öğe Application of well-defined ruthenium alkylidenes to the ROMP of norbornene derivatives: Methoxyphenyl-substituted polynorbornene dicarboximides(Elsevier Science Bv, 2011) Cetinkaya, Sevil; Ozker, Taner; Bayram, RifatThe applicability of ruthenium alkylidenes as initiators in the ring opening metathesis polymerization (ROMP) of methoxyphenyl group containing norbornene derivatives has been investigated. The synthesis and polymerization of exo-N-4-methoxyphenyl-oxanorbornene-5,6-dicarboximide (MeOPhONDI) and exo-N-4-methoxyphenyl-norbornene-5,6-dicarboximide (MeOPhNDI) are reported. Polynorbornene derivatives were obtained via ROMP using first- and second-generation ruthenium alkylidene initiators. The structural properties of the polynorbornene derivatives were analyzed by NMR, DSC and GPC. Analyses of the polymer microstructures indicate that polymers contain trans stereoconfiguration of the double bonds (55-86% trans-content). The glass transition temperatures of the polymers obtained from exo-monomers are higher than 211 degrees C. (C) 2010 Elsevier B.V. All rights reserved.Öğe Efficient Two Step Synthesis for Trimethylsiloxy-Functionalized New Polymers(Springer, 2019) Cetinkaya, Sevil; Yasar, EmineWe have presented an efficient strategy for the synthesis of trimethylsiloxy end-functionalized new polymers using ring-opening metathesis polymerization with ruthenium initiator, [(PCy3)(2)Cl2Ru=CHPh]. The key steps for the new silicon containing end-capped polymers are: In the first step, direct end-capping is carried out by adding cis-2-butene-1,4-diol to the ring-opened norbornene dicarboximides. In the second step, the reaction of hydroxy-functionalized polymers with trimethylsilyl chloride gives trimethylsiloxy-functionalized polymers. The best results for the end group introduction are achieved by reacting the living chains with an excess of the terminating agent. The molecular and structural features of the obtained polymers were confirmed by NMR and GPC analyzes, and their thermal properties were investigated by DSC. End-functionalization efficiency values were determined by NMR spectroscopy.Öğe Facile insitu preparation of silver nanoparticles supported on petroleum asphaltene-derived porous carbon for efficient reduction of nitrophenols(Cell Press, 2022) Erdem, Hikmet Beyza; Cetinkaya, SevilHerein, a facile in situ approach to synthesize catalytically active Ag nanoparticles supported on eco-friendly asphaltene-derived porous carbon (APC) was reported. Asphaltene-derived porous carbon was used as support for the first time for Ag@APC to prevent nanoparticles from aggregation, and then was evaluated as catalyst for the reduction of 4-nitrophenol (PNP), 2,4-dinitrophenol (DNP), and 2,4,6-trinitrophenol (TNP). The synthesized Ag nanoparticles were characterized by XRD, UV, BET, FESEM, TEM, and ICP analyses, revealing the formation of uniformly distributed, fcc structured crystalline Ag nanoparticles with BET surface area varied between 1500 and 1723 cm-1 with a porous carbon surface. Ag@APC nanocatalyst showed high catalytic efficiency in the reduction of nitrophenols in the presence of NaBH4 under mild conditions. The reduction of PNP, DNP, and TNP have pseudo -first-order rate constants of 0.3340, 0.2570, and 0.2408 min-1, respectively. The catalyst could be recyclable and reused for at least five successive runs without losing its original activity.Öğe Highly porous NiO/poly(DVB)HIPE nanocomposites for asphaltene removal: synthesis, kinetics, and thermodynamic studies(Springer, 2019) Ozker, Taner; Cetinkaya, SevilAsphaltene precipitation is one of the most important problems of the petroleum industry. Asphaltene collapses during petroleum processing and extraction from the well, blocking the pipes and causing many problems. For this reason, asphaltene should be removed from heavy crude oils to improve the quality of oil and prevent asphaltene deposition. In this study, for the first time, highly porous new polyHIPE nanocomposites containing NiO nanoparticles (NPs) have been prepared for asphaltene removal. The open-celled new poly(DVB)HIPE nanocomposites were synthesized by the polymerization of monomers in the external phase of water-in-oil emulsions containing NiO NPs in the organic phase. The highest surface area was obtained at 5 wt% of NiO NP loading (367 m(2)/g). The adsorption of asphaltenes from toluene solutions onto NiO/poly(DVB)HIPE nanocomposite was investigated in detail. Maximum adsorption was obtained as 384.6 mg/g at a temperature of 298 K for NiO/poly(DVB)HIPE nanocomposite. The Freundlich, Langmuir, and Temkin isotherm models were used to correlate the adsorption data of asphaltenes on NiO/poly(DVB)HIPE nanocomposite and adsorption constants of these models were calculated. The Freundlich and Langmuir gave better results at different temperatures. The pseudo-second-order kinetic model provided the best correlation with the experimental data (R-2 >= 0.997). The results of the thermodynamic experiments showed that the adsorption was spontaneous and exothermic. It is concluded that the polyHIPE nanocomposites are important for the oil industry owing to having potential use as an adsorbent.Öğe Influence of ruthenium alkylidene complexes bearing tricyclohexylphosphine or 3-bromopyridine ligand on the properties of fluorine containing polymers(Springer, 2013) Cetinkaya, Sevil; Ozker, Taner; Kaya, Pembe Hulya; Yasar, Emine; Bayram, RifatThe catalytic performance of ruthenium alkylidene complexes bearing tricyclohexylphosphine or 3-bromopyridine ligand in the ring opening metathesis polymerization (ROMP) of fluorine containing monomers, exo-N-4-fluorophenyl-7-oxanorbornene-5,6-dicarboximide (FPhONDI) and exo-N-4-fluorophenyl-norbornene-5,6-dicarboximide (FPhNDI) was investigated. Pure monomers were subjected to ROMP with RuCl2(PCy3)(2)(CHPh) (I), RuCl2(PCy3)(H(2)IMes)(CHPh) (II), RuCl2(3-Br-py)(2)(PCy3)(CHPh) (III) and RuCl2(3-Br-py)(2)(H(2)IMes)(CHPh) (IV). The polymers were fully characterized using NMR, DSC, SEM and GPC. Catalysts I-IV displayed significant ROMP activity, allowing for the synthesis of the corresponding polymers with polydispersity indices (PDIs) in the range of 1.4-4.0. High molecular weight polymers (Mw up to 4.95 x10(5)) were prepared in yields up to 90 %, depending on the initiator and monomer used.Öğe Investigation of the microstructure of metal catalyzed cyclopentene co-norbornene polymers by spectral methods(Springer, 2007) Cetinkaya, Sevil; Karabulut, Solmaz; Imamoglu, YavuzFor the first time, cyclopentene (CPE) has been copolymerized with the strained cycloolefin norbornene (NBE) using catalytic amounts of the electrochemically prepared metathesis catalyst. The microstructure of polymers was determined by H-1 NMR and C-13 NMR spectroscopy. The polymers were also characterized by differential scanning calorimetry and gel permeation chromatography (GPC) techniques.Öğe Mn3O4/p(DCPD)HIPE nanocomposites as an efficient catalyst for oxidative degradation of phenol(SPRINGER, 2020) Yesil, Rabia; Cetinkaya, SevilThe increase in the amount of wastewater containing organic pollutants in various industrial processes creates serious problems for the environment. Sulfate radical-based advanced oxidation process (AOP) is an effective route to remove pollutants from wastewater. However, designing a new nano-based catalyst to generate sulfate radicals is an important factor for the AOP. For this vision, porous trimanganese tetraoxide-polydicyclopentadiene (Mn3O4/pDCPD) nanocomposite, having an open-cell structure, was successfully designed via high internal phase emulsion (HIPE) and ring-opening metathesis polymerization (ROMP) approaches. The effect of Mn(3)O(4)nanoparticle concentration on the structure was investigated, and the resulting Mn3O4/p(DCPD)HIPE nanocomposites were fully characterized by FT-IR, XRD, FE-SEM, TEM, solid-state(13)C CPMAS NMR, DSC, and TGA analysis. The selected nanocomposite containing 5 wt% of Mn(3)O(4)was used as a model catalyst to mediate the heterogeneous oxidation of phenol in the presence of oxone. It is concluded that Mn3O4/p(DCPD)HIPE nanocomposite is a highly active catalyst to generate sulfate radicals for phenol degradation. Complete removal of 25 mg/L phenol was achieved in 30 min under the conditions of [catalyst] = 0.8 g/L, [oxone] = 2 g/L, andT = 25 degrees C. The phenol degradation followed the pseudo-first-order kinetic model, and the highest kinetic constant of 0.0611 min(-1)was achieved. No significant loss in the activity of the catalyst was determined after four consecutive cycles. Graphical abstractÖğe Petroleum asphaltene-derived highly porous carbon for the efficient removal of pharmaceutical compounds in water(Springer, 2022) Kabatas, Melike Burcu; Cetinkaya, SevilHighly porous carbons (PCs) were successfully developed through KOH chemical activation process from petroleum asphaltene for the efficient removal of pharmaceutical compounds (paracetamol and salicylic acid) from aqueous solution. The influences of activation temperature and the mixing types in chemical activation on the properties of the resulting PCs were investigated in detail by SEM, XRD, TGA, Raman, nitrogen adsorption-desorption, and CHNS elemental analyses. The PC with an extremely high surface area (2470 m(2)/g) was obtained by the impregnation method without modifier at an activation temperature of 850 degrees C. Adsorption kinetics was investigated with three kinetic models called the pseudo-first-order, the pseudo-second-order, and the intra-particle diffusion models, besides the adsorption equilibrium was analyzed using three widely used isotherm equations (Langmuir, Freundlich, and Temkin). The pseudo-second-order model was the best compatible with the experimental data for both organic compounds. This PC exhibited a high paracetamol adsorption capacity of 476.2 mg/g and a salicylic adsorption capacity of 500.0 mg/g in water. Thermodynamic analyzes confirmed that the adsorption was an exothermic process (Delta H-0 = - 18.63 kJ/mol) for paracetamol and an endothermic process (Delta H-0 = 53.96 kJ/mol) for salicylic acid. The linearized Freundlich and Langmuir models fitted the equilibrium data better than the others for paracetamol and salicylic acid, respectively.Öğe Preparation and characterization of new nanocomposite polymer films containing NiO nanofillers(Wiley, 2018) Cetinkaya, Sevil; Sonmez, Damla; Ozker, TanerNanocomposite solid polymer films based on the poly(exo-N-phenyl-7-oxanorbornene-5,6-dicarboximide) (PPhONDI)/LiClO4/NiO system have been designed, and the effect of inorganic NiO nanofiller in different amounts on the film properties has been examined. The exo-PPhONDI/LiClO4/NiO polymer system is the first solid nanocomposite polymer electrolyte film example based on a ring-opening metathesis polymerization (ROMP) host polymer. The NiO nanoparticles were prepared by two-step chemical syntheses, and the thermoplastic host polymer, exo-PPhONDI, was synthesized via ROMP. Composite polymer films were prepared by the solution-casting method. The amount of nanoparticles was varied from 1 to 15wt % of NiO. The conductivity of the nanocomposite solid polymer systems was influenced by the NiO nanofiller concentration. The composite films based on exo-PPhONDI ROMP polymer with the highest conductivity were achieved for the composition with 8 wt % of NiO nanofiller and 10 wt % of LiClO4 dopant. The prepared films were characterized using X-ray diffraction, Fourier transform infrared spectroscopy, differential scanning calorimetry, and scanning electron microscopy (SEM). The SEM results showed that the filler was well distributed in the polymer matrix. (c) 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45938.Öğe Preparation of a new nanoconductive ROMP copolymer and its application as solid polymer electrolyte(Elsevier Science Sa, 2013) Cetinkaya, Sevil; Buyun, Pembe Hulya KayaNew thermoplastic host copolymer based on oxanorbornene dicarboximides for solid polymer electrolytes was synthesized and characterized by spectral methods. The corresponding new nanoconductive ROMP copolymers were prepared through doping of lithium salt, LiBF4. The effect of lithium concentration on the conduction behavior of new SPEs was studied. The conductivity measurements were carried out on thin films of the nanostructured solid polymer electrolytes. The maximum conductivity (1.27 x 10(-5) S cm(-1)) was obtained for a copolymer complex with 10 wt.% LiBF4. (c) 2013 Elsevier B.V. All rights reserved.Öğe Synthesis and Catalytic Activity of PolyHIPE-Supported NHC-Bearing Ruthenium Initiator for ROMP(Springer, 2018) Unnu, Vesile Sima; Cetinkaya, SevilAlthough generally the ruthenium based homogeneous catalysts are used to initiate metathesis reactions, immobilization of homogeneous ruthenium metathesis catalysts on various solid supports has attracted a lot of interest from the scientific community in recent years. In this article, the synthesis and applications of highly active polyHIPE-supported N-heterocyclic carbene ligand (NHC)-bearing ruthenium alkylidene metathesis catalysts were described. Open-celled porous polyHIPE foams having surface area of 575 m(2)/g were synthesized by polymerization of the continuous phase of w/o high internal phase emulsions. Then RuCl2(PCy3)(H(2)IMes)(=CHPh) complex was attached to porous polyHIPE solid supports via alkylidene exchange reactions to obtain new olefin metathesis catalysts. The amount of initiator loadings was determined by ruthenium analysis via ICP-OES and found to be 0.0336-0.0514 mmol/g. Subsequently, the activity of new catalysts was tested in ring opening metathesis polymerization of norbornene and a series of its derivatives. [GRAPHICS] .Öğe Synthesis and catalytic evaluation of a ruthenium alkylidene complex bearing methoxy-pyridine ligand(Elsevier Science Bv, 2013) Cetinkaya, Sevil; Yasar, EmineModern well-defined ruthenium alkylidene complexes became preferred catalysts for a great variety of metathesis reactions. In this study, an air-stable new ruthenium alkylidene catalyst bearing 3-methoxypyridine has been prepared in one pot at high yields using commercially available [(PCy3)(2)Cl2Ru=CHPh] catalyst. Ruthenium based complex, (PCy3)(3-MeOPy)(2)(Cl)(2)Ru=CHPh, was characterized by a H-1 NMR doublet at 20.00 (J=11.9 Hz) for the Ru=CH proton. The catalyst was tested in model ROMP reactions and found to be very effective for ring-opening metathesis polymerization (ROMP). The optimal conditions for the polymerization of exo-N-benzylnorbornene-5,6-dicarboximide using the newly synthesized catalytic system were determined. (C) 2013 Elsevier B.V. All rights reserved.Öğe Synthesis of High-T-g Polymers via ROMP of Oxanorbornene Dicarboximides with Halogen Groups(Wiley-Blackwell, 2010) Cetinkaya, Sevil; Bayram, RifatThis paper describes the synthesis of exo-N-phenyl-7-oxanorbornene-5, 6-dicarboximides with different substituents at para positions in the aromatic ring and their polymerization by ring-opening metathesis polymerization (ROMP) leading to high-T-g polymers. Exo-N-4-chlorophenyl-7-oxanorbornene-5,6-dicarboximide (ClPhONDI, 3a), exo-N-4-bromophenyl-7-oxanorbornene-5,6-dicarboximide (BrPhONDI, 3b), and exo-N-4-iodophenyl-7-oxanorbomene-5,6-dicarboximide (1PhONDI, 3c) monomers were synthesized. Polynorbornene dicarboximides were obtained via ROMP using a first-generation ruthenium alkylidene catalyst, Cl-2(PCy3)(2)Ru(=CHPh). The resulting amorphous polymers with trans configuration of the double bonds were characterized by NMR, SEM, DSC, and GPC. (C) 2010 Wiley Periodicals, Inc. Heteroatom Chem 21:36-43, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20576
