Papers by Keyword: Platinum

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Authors: Ai Isohashi, Yasuhisa Sano, Shun Sadakuni, Kazuto Yamauchi
Abstract: A novel abrasive-free polishing method called catalyst-referred etching (CARE) has been developed. CARE can be used to chemically planarize a silicon carbide (SiC) surface with an etching agent activated by a catalyst. Platinum (Pt) and hydrofluoric (HF) acid are used as the catalyst and etchant, respectively. CARE can produce an atomically flat and crystallographically highly ordered surface of 4HSiC (0001) with a root-mean-square roughness of less than 0.1 nm regardless of the cut-off angle. However, industrial use of CARE is difficult because of HF acid usage. In this study, pure water was investigated as an alternative etchant to HF acid. We examined CARE using pure water by applying it to the planarization of a 4HSiC substrate and observed a feasible performance. The removal mechanism is considered to be the dissociative adsorption of water molecules to the SiC bonds of the topmost Si atom, namely the hydrolysis of the back bond, and the catalysis of Pt is considered to enhance the reaction. CARE with pure water is expected to represent a breakthrough method for surface processing of SiC, and will be widely applied in industrial processes such as planarization after high temperature processing in device fabrication.
Authors: Mohd Rashwan Taufiq Khairol Anwar, Norashikin Ahmad Zamanhuri, Junaidah Jai, Noorsuhana Mohd Yusof
Abstract: Platinum is commercially used in the catalytic industry for ages. The use of platinum has been significantly practiced because of its enhancing properties. There are a few advantages of using platinum such as high selectivity, high yield, high stability and able to undergo improvisation. However, when platinum lifetime is out, it is treated mainly as waste. Low recovery of platinum spent catalyst brought to the existence of recovery method using acidic and alkaline method. Proved to be harmful, green subtances were used as substitute for the chemical in recovering platinum. Therefore, a cheaper, safer and more environmentally method of recovery. Thus,this paper review about recovering platinum using palm oil leaf and how it is better than the existed chemical based method.
Authors: Kate P. Suppel, Jenny S. Forrester, Gregg J. Suaning, Erich H. Kisi
Abstract: Single crystal sapphire in one of four orientations (0001), (11 2 0), (1102) and (1010) was bonded to polycrystalline platinum foil at 1330oC under light load 20 N (0.8 MPa) in argon. The different orientations were used as a means to model individual grains within a polycrystal without the uncertain influence of grain boundaries and glass-forming contamination (e.g. SiO2). Partial bonding was observed in all cases. Optical microscopy, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) were used to study the nature of the bond which appears to be physical rather than chemical, in agreement with previous work.
Authors: Kazimierz Reszka, Jan Rakoczy, Jerzy Morgiel
Abstract: Good dispersion of active catalytic elements, their uniform distribution on the carrier’s surface and availability for neutralised combustion gases are key factors that determine the usability of catalyst cartridges for automotive catalytic reactors. By examining the morphology of oxide films, with SEM/STEM method, obtained by oxidation of foil coated with Pt/Al two-layered system (like laminate), where an Al nanofilm is situated between steel foil and a Pt nanofilm, one can observe forked and plate whiskers growing directly of substrate. Oxide films obtained from Pt+Al composite nanofilms were formed differently (where components are intermixed). These films are marked by chaotic, mutually penetrating fine equiaxed solids and whiskers. In case of composite nanofilms the grain system obtained in the course of deposition contributed to good Pt grain refining, and due to that mostly particles from 3 to 9 nm in conventional diameter were formed. Direct contact between Pt particles and Al particles caused the partial occlusion of Pt particles with oxide in the process of Al oxidation to be effected.
Authors: S. Tin, L. Zhang, A.P. Ofori, Michael K. Miller
Abstract: The elemental partitioning characteristics of advanced single crystal Ni-base superalloys containing additions of both Pt and Ru have been investigated using atom probe tomography. Detailed microanalysis revealed Ru additions partitioned preferentially to the disordered matrix, whereas Pt additions tended to partition to the ordered intermetallic γ′ precipitates. The partitioning characteristics of three nominally similar alloys with systematic variations in the levels of Cr, Ru and Pt were investigated. For this particular set of experimental alloys, minor changes in the partitioning characteristics of the constituent elements could be attributed to additions of Cr and Ru. The preferential site occupancy of Pt within the L12 lattice was also statistically quantified with ALCHEMI (atomic site location by channelling enhanced microanalysis). In contrast to the atomic partitioning characteristics of Ru, Pt exhibited a tendency to occupy the Ni sublattice sites in the γ′ structure.
Authors: P. Yong, I.P. Mikheenko, K. Deplanche, F. Sargent, Lynne E. Macaskie
Abstract: Bio-manufacturing of nano-scale palladium was achieved using bacterial cells. Highly active Pd-catalyst (Bio-Pd) produced by an E. coli mutant gave power output in a fuel cell. Up to ~115% of the maximum power generation was achieved by electrodes of Bio-Pd catalysts from Escherichia coli, compared to that from a commercial-Pd electrode (~0.099 W). A bio-precious-metals (Bio-PM) catalyst made directly from an industrial reprocessing solution by the E. coli was also made into fuel cell electrodes and ~0.06W of maximum power generation was observed.
Authors: B. Šljukić, N. Vukelić, S. Mentus
Authors: G. Postole, A. Gervasini, A. Auroux, B. Bonnetot
Abstract: In this study we report on the preparation and characterization of boron nitride supported noble metal catalysts with potential applications as catalysts for oxidation reactions. The deposition and the dispersion of the active phase were strongly influenced by the preparation process and in particular by the solvent used as the dispersing phase. Techniques such as BET, XRD and TEM were used to study the role played by the phase used as solvent (benzene, glyme, water, THF, diglyme, isopropanol, glycol) in particles size and dispersion of metals deposed on the BN support. Different palladium depositions under various conditions and different noble metal coatings under the same deposition condition are presented. The catalytic performances were tested in methane traces oxidation in excess oxygen and in the presence of water. The light-off temperature (50 % methane conversion) increased in the following order: Ag/BN < Pt/BN < Au/BN < Pd /BN.
Authors: Jana Mikulová, Sylvie Rossignol, Jacques Barbier Jr., Charles Kappenstein, Daniel Duprez
Abstract: Sol-gel Zr0.1Ce0.9O2 and Zr0.1(Ce0.75Pr0.25)O2 mixed oxides and coprecipitated pure ceria CeO2 displaying the fluorine type structure have been used as platinum or ruthenium catalysts’ supports for catalytic wet air oxidation (CWAO) of aqueous solution of acetic acid (78 mmol.L-1). These catalysts were prepared by conventional impregnation (5 wt-%) from platinum and ruthenium precursor salts or by exchange (~2 wt-%) in the case of ruthenium. A screening of catalysts in CWAO at 200°C under 2 MPa was performed and reveals that the best platinum catalyst is supported on pure ceria displaying large surface. For ruthenium catalysts, the highest conversion after 3 hours of reaction has been reached by the Ru/Zr-Ce-O system.
Authors: Alexey V. Zaikovskii, Sergey A. Novopashin, Salavat Z. Sakhapov, Dmitriy V. Smovzh
Abstract: Pt-C material was synthesized by arc-discharge method for application in creation of a gas diffusion electrode for an Al-air battery. The material was burned and mixed with graphite powder to replacement poor conductive carbon matrix, which closes Pt nanoparticles. Gas-diffusion electrodes produced by usage such materials have work characteristics of industrial level. Improving of work characteristic of gas diffusion electrodes is associated with increasing of electrical conductivity of carbon matrix which closes Pt nanoparticles. The arc discharge parameter dependence of structural and conductive properties of pure carbon material was studied, and it’s determined that the main parameter is buffer gas pressure. The carbon materials synthesized at pressure lower than 12 Torr have several times larger conductivity due to disappearance of the amorphous carbon layers and decreasing of contact resistance.
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