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Methanol Oxidation (methanol + oxidation)
Selected AbstractsThe Nanocrystalline Nickel with Catalytic Properties on Methanol Oxidation in Alkaline MediumFUEL CELLS, Issue 5 2009R. M. A. Tehrani Abstract The hexagonal closed packed (hcp) nanocrystalline nickel (Ni), with an average diameter of 9.7,±,2.27,nm was deposited uniformly on composite graphite (CG) by the rapid scanning (6,500,mVs,1) voltammetry technique. The hcp-nano Ni-modified CG electrode was investigated for the catalytic oxidation of methanol in alkaline medium through the formation of NiOOH. A high anodic current was obtained at peak potential of +570,mV vs Ag/AgCl. Both the scan rate and the methanol concentration affected the oxidation of methanol. The results showed that catalytic activity had increased with decrease in Ni particle diameter. It was also shown that the hcp-nano Ni/CG modified electrode was the most efficient catalyst in the oxidation of methanol. [source] Deposition of PtxRu1,x Catalysts for Methanol Oxidation in Micro Direct Methanol Fuel CellsISRAEL JOURNAL OF CHEMISTRY, Issue 3-4 2008William E. Mustain Platinum-ruthenium electrodes (PtxRu1-x) have been prepared by electrochemical and electroless deposition and investigated as catalysts for the oxidation of methanol in acidic solutions. PtxRu1-x deposits were electrochemically deposited from acidic chloride electrolytes at potentials between ,0.46 and 0.34 V (vs. NHE). The composition of the electrodeposit was estimated by energy dispersive X-ray spectroscopy and is a strong function of the electrode potential. An empirical model for the deposition process is presented and kinetic parameters are estimated and discussed. Also, the methanol oxidation activity of the PtxRu1-x catalysts was characterized by cyclic voltammetry in 1.0 M CH3OH, 1.0 M H2SO4 solutions. Electroless PtxRu1-x samples were prepared in a modified Leaman bath with hydrazine dihydrochloride as the reducing agent. The kinetic results for the electrochemical deposition of PtxRu1-x were directly applied and the deposition potential was estimated as approximately 0.40 V. [source] Determination of Optimum Conditions and the Kinetics of Methanol OxidationCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 1 2010A. H. Ulukardesler Abstract In this study, the catalytic oxidation of methanol to formaldehyde was investigated in a laboratory-scale fixed-bed catalytic reactor, under a large number of different conditions. Iron-molybdate catalysts supported by silica or alumina with a molybdenium/iron (Mo/Fe) ratio of 1.5, 3 and 5 were studied for the gas phase reaction. In order to obtain the optimum conditions, six different temperatures in the range of 250,375,°C and three different space times of 50.63, 33.75 and 20.25 g/(mol/h) were investigated. After determining the optimum conditions for this reaction, experiments aimed at understanding the reaction kinetics, were carried out. These experiments were performed on the catalyst favoring the formation of formaldehyde, which has a (Mo/Fe) ratio of 5 on a silica support. Seven reaction models derived by the mechanisms cited in the literature were tested to elucidate the kinetics of the reaction and the surface reaction controlling model was found to be the most suitable reaction mechanism. [source] Immersion Deposition of Pt Nanoparticles on Porous Silicon for Methanol OxidationCHINESE JOURNAL OF CHEMISTRY, Issue 9 2009Xu Su Abstract Porous silicon (PS) was chosen as the substrate for supporting the Pt particles because of great surface area, good conductivity and stability. Pt nanoparticles have been successfully prepared on the substrate by immersion deposition, which is convenient. The component and morphological properties of the films have been investigated by means of X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM), which shows that the Pt particles have small size and big specific surface. Cyclic voltammetry (CV) research showed that the Pt nanoparticles had novel catalytic activity for methanol when the immersion deposition time was past 24 min. [source] Synthesis of High-Surface-Area Platinum Nanotubes Using a Viral TemplateADVANCED FUNCTIONAL MATERIALS, Issue 8 2010. Górzny, Marcin Abstract A novel method for the synthesis of high-active-surface-area, platinum,tobacco mosaic virus (Pt,TMV) nanotubes is presented. A platinum salt is reduced to its metallic form on the external surface of a rod-shaped TMV by methanol, which serves as a solvent and reductant simultaneously. It was found that for the same Pt loading the Pt,TMV nanotubes had an electrochemically active surface area between 4 to 8 times larger than similarly sized Pt nanoparticles. A Pt,TMV catalyst displays greater stability in acidic conditions than those based on nanoparticles. When used as a catalyst for methanol oxidation, these Pt nanotubes display a 65% increase in catalytic mass activity compared to that based on Pt nanoparticles. [source] Analysis of Direct Methanol Fuel Cell (DMFC)-Performance via FTIR Spectroscopy of Cathode ExhaustFUEL CELLS, Issue 4 2003F. Meier Abstract Water and methanol flux through NafionÔ and polyaryl-blend membranes prepared at ICVT were studied under DMFC operation. The water, methanol, and CO2 content in the cathode exhaust were measured by FTIR spectroscopy. Both the water and methanol flux turned out to be strongly dependent on the operating temperature and thus on membrane swelling. Apart from this, water flux through the membrane is primarily affected by the gas volume flux on the cathode side. A coupling between water flux and methanol flux was observed, which leads to the conclusion that methanol is transported both by diffusion and by convection caused by the superimposed water flux. Polyaryl-blend membranes showed a reduced diffusive methanol transport when compared to NafionÔ due to their different internal microstructure. The impact of methanol cross-over on cathode losses at high current density needs further clarification with respect to the prevailing mechanism of methanol oxidation at the cathode. [source] Template Synthesis of Aligned Carbon Nanotube Arrays using Glucose as a Carbon Source: Pt Decoration of Inner and Outer Nanotube Surfaces for Fuel-Cell Catalysts,ADVANCED FUNCTIONAL MATERIALS, Issue 6 2008Zhenhai Wen A facile method is developed to synthesize aligned arrays of open-ended carbon nanotubes (CNTs) via in situ glucose polymerization in the inner pores of anodic aluminum oxide templates under hydrothermal conditions, followed by carbonization at high temperature. Pt nanoparticles are decorated on the surfaces of the as-prepared CNTs using the incipient wet method based on the use of NaBH4 as a reductant. Characterization of the resulting structures by transmission electron microscopy and field-emission scanning electron microscopy demonstrates that the Pt nanoparticles are anchored on both the inner and outer walls of CNTs, thus giving rise to a shell,core,shell-like nanotube composite. The electrocatalytic properties of the Pt,CNT,Pt electrodes are investigated for methanol oxidation by cyclic voltammetry and chronoamperometric measurements. It is found that the hybrid electrodes show superior catalytic performance compared to commercial carbon-black-supported Pt. The increased catalytic efficiency of Pt might be a result of the unique morphology of these structures. [source] Preparation of Pt,Ru Alloyed Thin Films Using a Single-Source CVD Precursor,CHEMICAL VAPOR DEPOSITION, Issue 3 2003S.-F. Huang Abstract Treatment of (dimethylaminomethyl)ruthenocene with cis -Pt(DMSO)2Cl2 led to the formation of a ruthenocenyl platinum complex [CpRu(,5 -C5H3CH2NMe2)Pt(DMSO)Cl] (1); subsequent treatment of 1 with [Na(hfac)] afforded an air-stable Pt,Ru complex [CpRu(,5 -C5H3CH2NMe2)Pt(hfac)] (2). Its volatility and other physical data relevant to CVD experiments were assessed by thermogravimetric analysis (TGA). The Pt,Ru thin films were then deposited at two deposition temperatures, 300,°C and 400,°C, using O2 as the reactive carrier gas. The as-deposited thin films were characterized using energy dispersive X-ray (EDX), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). Results indicated the formation of a homogeneous Pt,Ru solid solution at the lower deposition temperature. However, upon raising the temperature to 400,°C, phase separation between Pt and Ru occurred, which then induced the growth of RuO2 grains at the substrate surface and caused depletion of the alloy in ruthenium. The electrocatalytic activities of the films, in respect of methanol oxidation, were investigated, in half-cell experiments, by cyclic voltammetry. [source] | |||||||||||||