Carbon-supported platinum-based

Catalytic Dehydrogenation of Decalin and Methylcyclohexane over Carbon-Supported Platinum-Based Nanoparticles under Superheated Liquid-Film Conditions... 

The electro-catalytic oxidation of hydrogen, and reduction of oxygen, at carbon supported platinum based catalysts remain essential surface processes on which the hydrogen PEM fuel cell relies. The particle size (surface structure) and promoting component (as adsorbate or alloy phases) influence the activity and tolerance of the catalyst. The surface chemical behavior of platinum for hydrogen, oxygen, and CO adsorption is considered, in particular with respect to the influence of metal adsorbate and alloy components on close packed and stepped (defect) platinum surfaces. Dynamical measurements (employing supersonic molecular beams) of the... 

Due to slow kinetics, the conventional heterogeneous catalysis of the dehydrogenation of decalin in the solid-gas phase is performed at temperatures of more than 400 °C, which might result in the formation of by-products or carbonaceous deposit on the catalyst in addition to thermal energy loss. In a recent study, an attempt was made to apply the so-called liquid-film concept to hydrogen evolution from decalin with carbon-supported platinum-based catalysts under reactive distillation conditions in order to obtain high electric power suflficient for PEMFC vehicle operations in the temperature range 200-300°C [236]. 

The identification of the ethanol oxidation products and their quantification has been also carried out by means of DEMS. Behm and coworkers have studied thoroughly the distribution of products resulting of the electrooxidation of ethanol in acid medium at different temperatures and ethanol concentrations with carbon supported platinum-based catalysts... 

Approaches to Synthesize Carbon-Supported Platinum-Based Electrocatalysts for Proton-Exchange Membrane Fuel Cells... 

The feasibility of carbon-supported nickel-based catalysts as the alternative to the platinum catalyst is studied in this chapter. Carbon-supported nickel (Ni/C, 10 wt-metal% [12]), ruthenium (Ru/C, 10 wt-metal% [12]), and nickel-ruthenium composite (Ni-Ru/C, 10 wt-metal%, mixed molar ratio of Ni/Ru 0.25,1,4, 8, and 16 [12]) catalysts were prepared similarly by the impregnation method. Granular powders of the activated carbon without the base pretreatment were stirred with the NiCl2, RuC13, and NiCl2-RuCl3 aqueous solutions at room temperature for 24 h, respectively. Reduction and washing were carried out in the same way as done for the Pt/C catalyst. Finally, these nickel-based catalysts were evacuated at 70°C for 10 h. 

Park, S., Y. Xie, and M.J. Weaver, Electrocatalytic pathways on carbon-supported platinum nanoparticles Comparison of particle-size-dependent rates of methanol, formic acid und formaldehyde electrooxidation. Langmuir, 2002. 18(15) pp. 5792-5798 Vinodgopal, K., M. Haria, D. Meisel, and P. Kamat, Fullerene-based carbon nanostructures for methanol oxidation. Nano Letters, 2004. 4(3) pp. 415 18 Sun, N.X. and K. Lu, Physical Review B, 1997. 54 pp. 6058... 

In the present article, the size and the loading efficiency of metal particles were investigated by changing the preparation method of carbon-supported platinum catalysts. First, the effect of acid/base treatment on carbon blacks supports on the preparation and electroactivity of platinum catalysts. Secondly, binary carbon-supported platinum (Pt) nanoparticles were prepared using two types of carbon materials such as carbon blacks (CBs) and graphite nanofibers (GNFs) to check the influence of carbon supports on the electroactivity of catalyst electrodes. Lastly, plasma treatment or oxyfluorination treatment effects of carbon supports on the nano structure as well as the electroactivity of the carbon supported platinum catalysts for DMFCs were studied. 

In the present study, the size and the loading efficiency of metal particles were investigated by changing the preparation method of carbon-supported platinum catalysts. Furthermore, acld/base treatment effects of carbon blacks on the nano-structure as well as the electroactivity of the carbon-supported platinum catalysts for DMFCs were studied. 

Catalytic activity is closely dependent on the method of preparation, so considerable attention has been focused upon new preparation methods to improve the performance of carbon-supported platinum alloy catalysts in DMFC applications. The simultaneous reduction of metal salts [86-88], microwave-assisted reactions [89, 90], micro-emulsion-based synthesis [91-93], and the reduction of single-source molecular precursors [94-99] have been used to various extents. 

Platinum electrocatalysts are dispersed as small particles on high surface area conductive supports for effective use of costly Pt. The size of platinum particles, therefore, plays an important role in the oxygen reduction kinetics for fuel cell applications, in terms of both electrocatalytic activity and practical application of catalysts. Carbon-supported platinum shows a large surface area and increased catalytic activity. Alloy catalysts with various transition metals have been employed to increase the catalytic activity and reduce the cost. Various Pt-based alloy catalysts (binary, ternary, and quaternary alloy) have been tested over the last two decades. Many researchers have reported that Pt-based alloy catalysts show not only higher activity than Pt alone, but also exhibit good performance in the ORRs in PEFCs and DMFCs [100-108]. 

Ng, Y., Ikeda, S., Harada, T., etal. (2008). An Efficient and Reusable Carbon-Supported Platinum Catalyst for Aerobic Oxidation of Alcohols In Water, Chem. Common., 27, pp. 3181-3183. Dimitratos, N. and Prati, L. (2005). Gold Based Bimetallic Catalysts for Liquid Phase Applications, Gold Bull, 38, pp. 73-77. 

Regarding the ionomer (PFSl) content in a hydrophilic CL, the optimal amount and distribution of the ionomer in the CL is a tradeoff among three requirements (i) maximum contact between the ionomer and the Pt particles to guarantee proton transport, (ii) minimal electron resistance, and (iii) minimal gas transport resistance. Normally, gas transport can be affected by both decreased porosity due to the presence of a solid ionomer and liquid water accumulation due to the hydrophilicity of the CL. When carbon-supported platinum (Pt/C) is used as the catalyst, the carbon particles have a much larger surface area than the Pt particles, so only if the carbon surface is covered by the ionomer can contact between the ionomer and the Pt particles be ensured. This indicates that the ratio between the ionomer and the carbon in the CL is quite important for achieving high performance. The suggested ratio of ionomer to carbon I C) is about 0.8 1.0, which is calculated based on the assumption that the ionomer forms a thin layer ( 1 nm) on the carbon surface. 

Rhodium-on-carbon has also been found to bring about the formation of 2,2 -biquinoline from quinoline, the yield and the percentage conversion being similar to that obtained with palladium-on-carbon. On the other hand, rhodium-on-carbon failed to produce 2,2 -bipyridine from pyridine, and it has not yet been tried with other bases. Experiments with carbon-supported catalysts prepared from ruthenium, osmium, iridium, and platinum have shown that none of these metals is capable of bringing about the formation of 2,2 -biquinoline from quinoline under the conditions used with palladium and rhodium. ... 

Kaiser J, Simonov PA, Zaikovskii VI, Hartnig C, Joerissen L, Savinova ER. 2007. Influence of the carbon support on the performance of the platinum based oxygen reduction catalysts in a pol3mier electrol3fte fuel cell. J Appl Electrochem 37 1429-1437. 

Platinum-based nanoparticles (e.g., Pt [1-15], Pt-Re [10,15], and Pt-W [5,6,15]) supported on granular activated carbon (KOH-activation, BET specific surface area 3100 m2/g, pore volume 1.78 cm3/g, average particle size 13 pm, average pore size 2.0 nm, Kansai Netsukagaku Co. Ltd. [32]) were mainly used as the dehydrogenation catalysts in the present study. 

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