Carbon supported platinum-palladium catalysts for methanol and ethanol oxidation reactions

Öztürk, Zafer
In this work, two groups of carbon supported Pt-Pd catalysts have been prepared in order to investigate the effect of Pd, as a second metal, and surfactants on the catalytic activity towards methanol and ethanol oxidation reactions used in the direct methanol and ethanol fuel cells. In the first group (group a), 1- hexanethiol was used as a stabilizing agent while in the second group (group b), 1,1 dimethyl hexanethiol was utilized. Cyclic voltammetry (CV), chronoamperometry (CA), X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) were used in order to determine the nature of the catalysts. The average crystalline size of the metal particles in the catalysts was explored by XRD and TEM. TEM results revealed the uniform distribution of the metal nanoparticles on carbon support with a narrow size distribution in the range of 3.0 to 3.7 nm and the average crystalline sizes of metal particles for group “b” catalysts were larger than that of group “a” catalysts which can be explained by the surfactant effect. These results were in good agreement with XRD data. The oxidation states of platinum (Pt(0) and Pt(IV)) and palladium (Pd(0) and Pd(II)) and their ratios were investigated by XPS and for the most active catalyst, catalyst Ib, these ratios were found to be as 6.94 and 13.7, respectively. Electrochemical activities of the catalysts towards methanol and ethanol oxidation reactions were recorded and compared with that of Pt/C and the commercial Pt (ETEK 20 %wt) catalysts. The results indicated that the group ‘b’ catalyst has greater catalytic activities than that of group ‘a’ catalysts. Catalyst Ib comes into prominence as the most active catalyst due to its superior characteristics that it possess such as highest extent of alloying with respect to the palladium amount used, active surface area, CO-tolerance, stability and Pt (0) to Pt (IV) and Pd (0) to Pd (II) ratios.


Vulcan-Supported Pt Electrocatalysts for PEMFCs Prepared using Supercritical Carbon Dioxide Deposition
Bayrakceken, Ayse; Smirnova, Alevtina; Kitkamthorn, Usanee; Aindow, Mark; Tuerker, Lemi; Eroğlu, İnci; ERKEY, CAN (Informa UK Limited, 2009-01-01)
In this study, supercritical carbon dioxide (scCO(2)) deposition was used to prepare vulcan-supported Pt (Pt/Vulcan) electrocatalysts for proton exchange membrane fuel cells (PEMFCs), and the effects of process variables on the properties of the electrocatalysts were investigated. The two different methods used to reduce the organometallic precursor were thermal reduction in nitrogen at atmospheric pressure and thermal reduction in scCO(2). In the former method, the maximum Pt loading achieved was 9%, and t...
Kinetic analyses of the effects of temperature and light intensity on growth, hydrogenm production and organic acid utilization by rhodobacter capsulatus
Sevinç, Pelin; Gündüz, Ufuk; Department of Biotechnology (2010)
Effects of temperature and light intensity on photofermentative hydrogen production by Rhodobacter capsulatus DSM1710 by use of acetic and lactic acids as substrates were studied. Experiments were conducted at 20, 30 and 38oC incubator temperatures under light intensities in the 1500 – 7000 lux range. pH of the medium and quantity of hydrogen forming together with quantity of biomass, and concentrations of acetic, lactic, formic, butyric and propionic acids in the medium were determined periodically. Growth...
Activity Comparison of MCM-41 and V-MCM-4 Catalysts for Ethanol Selective Oxidation and DRIFTS Analysis
Gucbilmez, Yesim; Doğu, Timur; BALCI, FATMA SUNA (2009-01-01)
The activity of a V-MCM-41 catalyst with a V/Si molar ratio of 0.04 was compared with the activity of a pure MCM-41 catalyst and some DRIFTS studies were performed in order to understand the mechanism of selective oxidation of ethanol. V-MCM-41 was found to be much more active than pure MCM-41, favouring the formation of high amounts of ethylene over 300 degrees C. MCM-41, on the other hand, was found to favour the formation of acetaldehyde over ethylene at all studied temperatures. It was shown by reaction...
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Water soluble polymer stabilized iron(0) nanoclusters were prepared from the reduction of iron(III) chloride by sodium borohydride (SB) and ammonia borane (AB) mixture in the presence of polyethylene glycol (PEG) as stabilizer and ethylene glycol as solvent at 80 degrees C under nitrogen atmosphere. PEG stabilized iron(0) nanoclusters were isolated from the reaction solution by centrifugation and characterized by UV-Vis, TEM, HRTEM, XRD, ICP-OES and FT-IR methods. The particle size of PEG stabilized iron(0)...
Preparation and characterization of carbon supported platinum nanocatalysts with different surfactants for C1 to C3 alcohol oxidations
Ertan, Salih; Gökağaç Arslan, Gülsün; Department of Chemistry (2011)
In this thesis, carbon supported platinum nanoparticles have been prepared by using PtCl4 as a starting material and 1-octanethiol, 1-decanethiol, 1-dodecanethiol and 1-hexadecanethiol as surfactants for methanol, ethanol and 2-propanol oxidation reactions. The structure, particle sizes and surface morphologies of the platinum were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM) and transmission electron microscopy (TEM). XRD and TEM results indicate that all prepared catalysts have ...
Citation Formats
Z. Öztürk, “Carbon supported platinum-palladium catalysts for methanol and ethanol oxidation reactions,” M.S. - Master of Science, Middle East Technical University, 2011.