Preperation and characterization of carbon supported platinum nanoparticles for methanol oxidation reactions

Çokangın, Aysu
In this thesis, carbon supported platinum nanoparticle catalysts were synthesized by using PtCl4 as precursor, sodium borohydride (Cat I), hydrazinum hydroxide (Cat II) and formaldehyde (Cat III) as reducing agent and 1-heptanamine (a), Nmethylheptanamine (b) and N,N-dimethylheptanamine (c) as surfactants for methanol oxidation reaction. Their physical and electrochemical properties were determined by inductively coupled plasma spectroscopy (ICP), cyclic voltammetry (CV), and characterization methods of X-ray diffraction (XRD), X-photoelectron Spectroscopy (XPS), transmission electron microscopy (TEM) and Brunauer, Emmnett and Teller (BET) surface area analysis. XRD and TEM results indicated that all catalysts exhibit face centered cubic structure and contain small and agglomerated platinum particles in different shape, size, ratio and density. Cat I composed of small (~ 5 nm) and significant number of quite dense spherical agglomerated (~ 20 - ~ 150 nm) particles, Cat II comprises small (~ 5 nm) cubic and formless agglomerated (~ 20 - ~ 300 nm) particles and Cat vi III contains large number of small (~ 5 nm) and a few number of spherical, less dense and agglomerated (~ 20 - ~ 200 nm) particles. XPS data displayed that platinum exist in two different oxidation states, Pt(0) (~64.5~69.6 %) and Pt(IV) (~35.5-~30.4 %) and platinum surface includes adsorbed OH, H2O, C-O, C=O, C-OH, partially crystalline carbon and/or hydrocarbon. BET analysis showed that the surface area of the Cat Ia, IIa, IIIa, Ib, IIb, IIIb, Ic, IIc and IIIc are 27.58, 27.88, 36.25, 5.44, 6.27, 6.22, 26.80, 32.50 and 52.88 m2/ g Pt respectively. The highest surface area recorded to catalyst IIIc. These results illustrated that surface area of the catalyst depends on the reducing agent that was used. However no trace was found to indicate the surfactant effect on the surface area of catalysts. Electrochemical studies revealed that the order of performance of catalysts towards methanol oxidation reaction is Catt II < Cat I < Cat III and Cat IIIc has the highest performance, which is 2.23 times larger than E-TEK catalyst. It was found that the performance of catalysts depends on the kind of surfactant and reducing agent, electrochemical surface area, percent platinum utility, roughness factor, and If / Ir ratio.


Carbon-supported PT nanoparticles prepared by new surfactants and different reducing agents for methanol oxidation reaction
Kalyoncu, Sevda; Gökağaç Arslan, Gülsün; Department of Chemistry (2015)
In this thesis, carbon supported platinum catalysts were synthesized to investigate the effect of reducing agent and surfactant on the performance of catalyst towards methanol oxidation reaction. For this purpose, the catalysts were prepared by using PtCl4 as a starting material, propylamine (a) and dipropylamine (b) as surfactant, and sodium borohydride (catalyst I) and formaldehyde (catalyst II) as reducing agent. The prepared catalysts were characterized by X-ray diffraction (XRD), transmission electron ...
Sorption of radioactive cesium and barium ions onto solid humic acid
Celebi, O.; Kilikli, A.; ERTEN, HASAN NİYAZİ (Elsevier BV, 2009-09-15)
In this study, the sorption behavior of two important fission product radionuclides ((137)Cs and (140)Ba) onto sodium form of insolubilized humic acid (INaA) were investigated as a function of time, cation concentration and temperature, utilizing the radiotracer method. The sorption processes are well described by both Freundlich and Dubinin-Radushkevich type isotherms. Thermodynamic constants such as: free energy (Delta G(ads)), enthalpy (Delta H(ads)), entropy (Delta S(ads)) of adsorption were determined....
Synthesis of 2-iodomethylene-2,3-dihydro-1,4-oxazepine derivatives
Çakal, Deniz; Zora, Metin; Department of Chemistry (2014)
In this thesis, platinum nanoparticles were prepared by using PtCl4 as a starting material, sodium borohydride (Group I), hydrazine (Group II) and formaldehyde (Group III) as reducing agents and hexylamine (Group -a), N-methylhexylamine (Group -b), N,N-dimethylhexylamine (Group -c) as surfactants (the last two surfactants were used for the first time). These platinum nanoparticles were dispersed on Carbon XC-72 to be utilized as catalyst for methanol oxidation reaction which can be used in direct methanol f...
Poly(n-vinyl-2-pyrrolidone) stabilized nickel(0) nanoparticles as catalyst for hydrogen generation from the methanolysis of ammonia borane
Kılıçaslan, Nihan Zülay; Özkar, Salim; Department of Chemistry (2015)
This dissertion includes the preparation and characterization of poly(N-vinyl-2-pyrrolidone) stabilized nickel(0) nanoparticles, and investigation of their catalytic activity in hydrogen generation from catalytic methanolysis of ammonia-borane (AB). PVP-stabilized nickel(0) nanoparticles were prepared from the reduction of nickel(II) ethylhexanoate in the presence of PVP as stabilizer, by hydrazine borane at room temperature. PVP-stabilized nickel(0) nanoparticles were isolated from reaction medium by centr...
Heteropolyacid Incorporated Bifunctional Core-Shell Catalysts for Dimethyl Ether Synthesis from Carbon Dioxide/Syngas
Core-shell-type catalysts, which are synthesized by encapsulating the Cu-ZnO-Alumina type methanol synthesis catalyst (CZA) by silicotungstic acid (STA)-incorporated mesoporous alumina, were prepared following a hydrothermal route and tested in DME synthesis from syngas and CO2. Activity tests, which were performed in the pressure range of 30-50 bar, and the temperature range of 200-300 degrees C, with different feed compositions (CO2/CO/H-2: 50/-/50, 40/10/50, 25/25/50, 10/40/50) showed that the best-opera...
Citation Formats
A. Çokangın, “Preperation and characterization of carbon supported platinum nanoparticles for methanol oxidation reactions,” M.S. - Master of Science, Middle East Technical University, 2015.