Platinum

About: Platinum is a research topic. Over the lifetime, 49675 publications have been published within this topic receiving 1150035 citations. The topic is also known as: Pt & element 78.

Comparison of Pt/zeolite catalysts for n-hexadecane hydroisomerization

Abstract: Bifunctional platinum (0.5 wt.%) catalysts containing ZSM-5, ZSM-22, SAPO-11, Al-MCM-41, H-Y and H-β were tested for the hydroisomerization of n-hexadecane and their catalytic activities were compared. The Pt/ZSM-5, Pt/ZSM-22 and Pt/H-β catalysts showed higher hydrocracking activity due to their strong acid sites, while the Pt/SAPO-11, Pt/Al-MCM-41 and Pt/H-Y catalysts with moderate acid strength showed better isomerization selectivity. Especially the Pt/Al-MCM-41 catalyst, where Al-MCM-41 was prepared by post-synthetic metal implantation method from siliceous MCM-41, showed the highest isomerization selectivity as well as the highest yield of multibranched isohexadecanes, presumably not only due to its moderately weak acidity and mesoscale pores but also due to higher metal dispersion. This result indicates that the Pt/Al-MCM-41 catalyst can be a promising candidate for good dewaxing catalysts.

Mechanism of the Catalytic Oxidation of Glycerol on Polycrystalline Gold and Platinum Electrodes

Abstract: This paper addresses the oxidation mechanism of glycerol on Au and Pt electrodes under different pH conditions. Intermediates and/or reaction products were detected by using an online high-performance liquid chromatography technique (for soluble products) and online electrochemical mass spectrometry (for CO2). In alkaline media, the main product of glycerol oxidation on the Pt electrode is glyceric acid produced via glyceraldehyde. Glyceric acid is the primary oxidation product on the Au electrode, which is further oxidized to glycolic acid and formic acid at high potentials (≥0.8 V), yielding high current densities. As the pH of the solution is lowered, the glycerol oxidation becomes significantly more sluggish on both Au and Pt electrodes, which results in glyceraldehyde being the main oxidation product under neutral conditions, especially on gold. In acidic solutions, only the Pt electrode shows catalytic activity with a relatively low conversion rate, mainly to glyceraldehyde. At positive potentials corresponding to the formation of a Pt surface oxide, the PtOx surface oxide catalyzes the conversion of glyceraldehyde finally to formic acid and CO2, but only under acidic conditions. Gold catalyzes glycerol oxidation only under alkaline conditions, in contrast to a “real catalyst,” that is, platinum, which catalyzes glycerol oxidation over the entire pH range.

Reaction Mechanism Studies on Atomic Layer Deposition of Ruthenium and Platinum

Abstract: Reaction mechanisms in atomic layer deposition (ALD) of ruthenium from bis(cyclopentadienyl)ruthenium (RuCp 2 ) and oxygen were studied in situ with a quadruple mass spectrometer (QMS) and a quartz crystal microbalance (QCM). In addition, QMS was used to study ALD of platinum from (methylcyclopentadienyl)trimethylplatinum (MeCpPtMe 3 ) and oxygen. The QMS studies showed that the reaction by-products H 2 O and CO 2 were released during both the oxygen and the metal precursor pulses. Adsorbed oxygen layer on the metal surface thus oxidizes part of the ligands during the metal precursor pulse. The remaining ligand species become oxidized and a new layer of adsorbed oxygen forms on the surface during the following oxygen pulse. The QCM analysis of the ruthenium process showed a mass decrease during the RuCp 2 pulse and a mass increase during the oxygen pulse, which further supports the proposed mechanism.