Browsing by Author "Yasar, Alper O."

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0d, 1d, 2d, and 3d Soft and Hard Templates for Catalysis
(Elsevier Science Bv, 2017) Butun, Sultan; Demirci, Sahin; Yasar, Alper O.; Sagbas, Selin; Aktas, Nahit; Sahiner, Nurettin
An Alternative To Metal Catalysts: Poly(4-Vinyl Pyridine]-Based Polymeric Ionic Liquid Catalyst for H2 Generation From Hydrolysis and Methanolysis of Nabh4
(Pergamon-elsevier Science Ltd, 2016) Sahiner, Nurettin; Yasar, Alper O.; Aktas, Nahit
Monodispersed p(4-VP) (poly(4-vinyl pyridine)) polymeric particles were synthesized via self-emulsion polymerization and modified with 1,2-dibromobutane 1,4-dibromobutane and 1,6-dibromobutane, to obtain polymeric ionic liquid (PIL) particles of poly(4-vinyl pyridine)-dibromoethane (p(4-VP)C-++(2)), poly(4-vinyl pyridine)-dibromobuthane (p(4-VP)C-++(4)), and poly(4-vinyl pyridine)-dibromohexane (p(4-VP)C-++(6)) particles. Highly mono dispersed p(4-VP), p(4-VP)C-++(2), p(4-VP)C-++(4) and p(4-VP)C-++(6) particles were obtained with the sizes of 335 +/- 10, 451 +/- 17, 432 +/- 13 and 443 +/- 24 nm, and the zeta potential values of 6.3 +/- 0.6, 31.2 +/- 2.1, 33.3 +/- 1.0 and 35.5 +/- 1.1 mV. PIL-metal composites of p(4-VP)C-++(6)-Co p(4-VP)C-++(6)-Ni and p(4-VP)C-++(6)-Fe particles were prepared by reducing CoCl2, NiCl2 and FeC13 metal salts loaded into p(4-VP)C-++(6) microgels and then reducing with NaBH4. The prepared PIL-metal composites and PIL particles were used as catalysts in H-2 generation from the hydrolysis and methanolysis of NaBH4. It was found that the prepared PIL-metal composites (e.g., p(4-VP)C-++(6)-Co) showed better catalytic performances than PIL particles (e.g., p(4-VP)C-++(6)) for the hydrolysis reaction of NaBH4 whereas, PIL catalytic performances were much better than PIL-metal composites for the methanolysis of NaBH4. Various parameters affecting the hydrolysis and methanolysis reactions of NaBH4 such as the types of PIL/PIL-metal particle, the amount of PIL particles, the amount of NaBH4 and temperature were investigated. A very high hydrogen generation rate (HGR) value for the methanolysis reaction of 500 mM NaBH4 catalyzed by 50 mg p(4-VP)C-++(6) at 25 degrees C was calculated as 9125 +/- 177 mL H-2 (g of catalyst min)(-1). Furthermore, very low activation energy (Ea), 13.78 +/- 0.23 kJ morl was calculated for the methanolysis of NaBH4 catalyzed by p(4-VP)C-++(6) at temperatures in the range of 0-40 degrees C. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Dicationic Poly(4-Vinyl Pyridinium) Ionic Liquid Capsules as Template for Co Nanoparticle Preparation and H2 Production From Hydrolysis of Nabh4
(Elsevier Science inc, 2015) Sahiner, Nurettin; Yasar, Alper O.; Aktas, Nahit
Poly(4-vinyl pyridine)-silica (p(4-VP)-silica) composites were synthesized via micro emulsion polymerization, and the capsule of p(4-vinyl pyridine), as cap-p(4-VP), was prepared by removing the core silica from p(4-VP)-silica composites by HF treatment. Dicationic particles in the form of cappoly(4-vinyl pyridine)(++)-1,4-butane (cap-p(4-VP)(++)-C-4), capsule-poly(4-vinyl pyridine)(++)-1,6-hexane (cap-p(4-VP)(++)-C-6), and capsule-poly(4-vinyl pyridine)(++)-1,8-octane (cap-p(4-VP)-C-8) were prepared by modifying cap-p(4-VP) particles with corresponding dibromo alkanes. Then, polymer-metal composites were also prepared from cap-p(4-VP) and dicationic cap-p(4-VP) particles by loading CoCl2 from ethanol and the obtained composites were used in H-2 generation from hydrolysis of NaBH4, and The Ea for the composite catalyst was calculated as 56.53 kJ/mol. (C) 2014 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.
H2 Generation From Nabh4 Methanolysis Via Magnetic Field Sensitive Ionic Liquid Coated Silica Particles as Catalyst
(Elsevier, 2017) Sahiner, Nurettin; Yasar, Alper O.; Aktas, Nahit
Upon the preparation of magnetic (Fe3O4) nanoparticles (NPs), they were coated with amino-functionalized silica (SiO2@NH2) via the modified Stber method. Siv coated Fe3O4 (Fe3O4@SiO2) particles and SiO2@NH2 coated Fe3O4 (Fe3O4@SiO2@NH2) particles were turned into ionic liquid (IL) colloids as Fe3O4@SiO2@NH3+Cl-, Fe3O4@SiO2@NH3+NO3- and Fe3O4@SiO2@NH3+HSO4- by the treatment of Fe3O4@SiO2@NH2 with hydrochloric acid (HCl), nitric acid (HNO3) and sulfuric acid (H2SO4), respectively. The size of the prepared silica-based particles was approximately 500 nm by SEM images, and the zeta potential values varying between -59 and +26 mV. The catalytic activity performances of these silica-based particles as catalysts were investigated for H-2 generation from methanolysis of NaBH4 in terms of the types of particles, reusability, recyclability, the concentration of NaBH4, and the reaction temperature. Amongst the prepared IL colloids, Fe3O4@SiO2@NH3+Cl- particles were found to be the most effective catalysts for the methanolysis reaction of NaBH4. The maximum Hydrogen Generation Rate (HGR) value of 13188 +/- 196 mL H-2 g(-1) min(-1) was attained at 500mM NaBH4 by using 50 mg Fe3O4@SiO2@NH3+Cl- as catalyst at 25 degrees C. Additionally, turn over frequency (TOF) value was calculated as 43.1 +/- 3.1 H-2 mol (mol of N.min)(-1) for Fe3O4@SiO2@NH3+Cl- under the same reaction conditions. Moreover, activation energy (Ea) values for the methanolysis of NaBH4 using Fe3O4@SiO2@NH3+Cl- particles as catalyst were found as 32.5 +/- 0.5, 39.9 +/- 0.3 and 24.4 +/- 0.7 kJ mol(-1) in the temperature range of -15-45, -30-0 and 15-45 degrees C, respectively, that are comparable and even better than for most of the metal nanoparticle catalysts used in NaBH4 methanolysis reactions.
Metal-Free Pyridinium-Based Polymeric Ionic Liquids as Catalyst for H2 Generation From Nabh4
(Pergamon-elsevier Science Ltd, 2017) Sahiner, Nurettin; Yasar, Alper O.; Aktas, Nahit
Monodispersed poly(2-vinyl pyridine) (p(2-VP)) polymeric particles were synthesized with a self emulsion polymerization (SEP) technique. Polymeric ionic liquid (PIL) particles such as poly(2-vinyl pyridine)-ethane (p(2-VP)C-++(2)), poly(2-vinyl pyridine)-butane (p(2-VP)C-++(4)), and poly(2-vinyl pyridine)-hexane (p(2-VP) C-++(6)) particles were then prepared from monodispersed p(2-VP) particles by modifying with 1,2-dibromobutane (DBE) 1,4-dibromobutane (DBB) and 1,6-dibromobutane (DBH), respectively. The hydrodynamic diameter of the prepared particles was found be in the range of 350 -400 nm, and the zeta potential of p(2-VP)C-++(n) (n: 2, 4 and 6) particles were found to be in the range of 26-28 my. The prepared PIL particles (p(2-VP)C-++(6) etc.) were shown to be very effective catalysts in H-2 generation by methanolysis of NaBH4. Various parameters, such as the effect of modifying agents on PIL particle, the amount of PIL particles, the amount of NaBH4 and temperature, affecting the H-2 production rate were investigated. Hydrogen generation rate (HGR) was calculated as 5433 +/- 141 mL H-2 g(-1) min(-1) for 50 mg p(2-VP)C-++(6) particles in the methanolysis of 500 mM NaBH4. The activation energy (Ea) of methanolysis of NaBH4 catalyzed by p(2-VP)C-++(6) particles was calculated as 20.84 +/- 0.76 kJ mol(-1), which is much lower than similar studies reported in the literature. (C) 2016 Elsevier Ltd. All rights reserved.