Efficient hydrogen peroxide decomposition on bimetallic Pt–Pd surfaces (original) (raw)
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American journal of chemistry, 2019
Bi-metallic Pt-Pd catalytic films were immobilized on Nafion-117 membrane to decompose hydrogen peroxide. A basic medium helps to enhance autocatalysis of hydrogen peroxide decomposition reaction. Although H 2 O 2 decomposition is strongly increased by the presence of iodide ions and sodium dodecyl sulfate species but they deactivate the catalytic surface. Among several sulfate salts (CoSO 4 .7H 2 O, K 2 SO 4 and CuSO 4), only NiSO 4 .7H 2 O influenced to increase the reaction rate. Meanwhile, the Hg 2+ species not only inhibits the decomposition process but also permanently damage the activity of the catalytic surface.
The Direct Synthesis of Hydrogen Peroxide Using Platinum-Promoted Gold-Palladium Catalysts
Angewandte Chemie International Edition, 2014
The direct synthesis of hydrogen peroxide offers a potentially green route to the production of this important commodity chemical. Early studies showed that Pd is a suitable catalyst, but recent work indicated that the addition of Au enhances the activity and selectivity significantly. The addition of a third metal using impregnation as a facile preparation method was thus investigated. The addition of a small amount of Pt to a CeO 2 -supported AuPd (weight ratio of 1:1) catalyst significantly enhanced the activity in the direct synthesis of H 2 O 2 and decreased the non-desired over-hydrogenation and decomposition reactions. The addition of Pt to the AuPd nanoparticles influenced the surface composition, thus leading to the marked effects that were observed on the catalytic formation of hydrogen peroxide. In addition, an experimental approach that can help to identify the optimal nominal ternary alloy compositions for this reaction is demonstrated.
The Journal of Physical Chemistry C, 2016
Structural and morphological characterisation of bimetallic Pd-Pt/Al 2 O 3 model catalysts are performed using X-ray diffraction, X-ray absorption spectroscopy, transmission electron microscopy and CO chemisorption. Further, the catalysts were studied under oxidising and reducing conditions using both X-ray absorption spectroscopy and low-energy ion scattering spectroscopy. For the as-prepared catalysts, the existence of alloyed bimetallic Pd-Pt particles and of (tetragonal) PdO were found for the samples calcined at 800 C. PdO is present in form of crystals at the surface of the Pd-Pt particles or as isolated PdO crystals on the support oxide. Bimetallic Pd-Pt nanoparticles were only formed on the Pd-Pt catalysts after calcination at 800 C. The results show that the Pd-Pt nanoparticles undergo reversible changes in surface structure composition and chemical state in response to oxidising or reducing conditions. Under oxidising conditions Pd segregates to the shell and oxidises forming PdO, while under reducing conditions regions with metallic Pd and Pd-Pt alloys were observed at the surface. No bimetallic Pd-Pt nanoparticles were observed for the sample initially calcined at 500 C, but instead isolated monometallic particles, where small Pt particles are easily oxidised under O 2 treatment. In the monometallic catalysts, the Pd is found to be completely oxidised already after calcination and to consist of metallic Pd after reductive treatment.
Decomposition of Hydrogen Peroxide using Chemical and Catalytic Methods: A Reactor-based Approach
Asian Journal of Chemistry
A feasible catalytic reactor for oxygen evolution has been proposed, which could complement the current methods of O2 evolution efficiently and ensure the availability of pure oxygen on a wider scale. Several chemicals, such as NaI, MnO2, NiSO4, etc. can generally decompose hydrogen peroxide by producing oxygen as a product via chemical reactions. Meanwhile, the Pt-Pd catalyst efficiently catalyzes hydrogen peroxide decomposition reactions and generates pure oxygen without any unfriendly species. The excellence of the bi-metallic catalyst has been validated by the evaluation of turnover number (TON) and turnover frequency (TOF). Implementing the knowledge of chemical reactions and heterogenous catalysis, the proposed catalytic reactor could be helpful for generating a continuous flow of oxygen. Surely, the oxygen produced in this process is higher in amount compared to the oxygen present in the atmosphere at ambient conditions which might facilitate the breathing support for critica...
Electrochimica Acta, 2015
The understanding of the intrinsic properties of Pt and Pd is important for the rational design of catalysts for methanol and ethanol oxidation in alkaline media. In this paper, Pd catalysts, Pt catalysts and bimetallic PtPd catalysts supported on nitrogen-doped graphene are investigated. The cyclic voltammograms (CVs) for the bimetallic catalysts in 1 M KOH solution demonstrate the increasing surface composition of Pt versus Pd. The linear sweep voltammetry results show that the onset potential for OH formation on Pt is lower than on Pd, indicating that Pt has a higher affinity for OH than Pd. The CVs recorded for methanol and ethanol oxidation show that ethanol oxidation occurs at lower potentials, suggesting that ethanol is a more active fuel than methanol. Ethanol and methanol oxidation occurs at lower potentials on Pt than on Pd, revealing that Pt is intrinsically more active than Pd. Chronoamperometry results show that the rate of catalysts deactivation during ethanol oxidation is more severe compared with methanol oxidation, especially for catalysts with higher Pt content. The possible reason for the deactivation behaviors is presented and recommendations are given for future catalysts development.
Journal of Catalysis, 2012
The direct synthesis of hydrogen peroxide using supported gold palladium catalysts prepared by incipient wetness impregnation is described and discussed. The effect of an acid pre-treatment step on the activated carbon support prior to the deposition of the metals, together with the effect of the calcination temperature, has been investigated. The acid pre-treated samples all show superior activity to those materials prepared with the omission of this acid pre-treatment stage. The calcination temperature affects both the re-usability and hydrogenation activity of the catalysts. Detailed characterisation using X-ray photoelectron spectroscopy and aberration-corrected scanning transmission electron microscopy is described. The enhanced activity is associated with a higher surface concentration of palladium in the acid pre-treated samples which is principally present as Pd 2+. Calcination of the catalysts at 400°C is required to achieve re-usable and stable catalysts, and this is associated with the morphology and dispersion of the metal nanoparticles. The surface ratio of Pd 0 /Pd 2+ is found to be an important factor controlling the hydrogenation of hydrogen peroxide, and a series of controlled reduction and re-oxidation of a sample show how the Pd 0 /Pd 2+ surface ratio can influence the relative rates of hydrogen peroxide synthesis and hydrogenation.
42nd AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit, 2006
Alta S.p.A. (Italy) and DELTACAT Ltd. (United Kingdom) are conducting a study, funded by the European Space Agency, into the development of hydrogen peroxide monopropellant thrusters using advanced catalytic beds. The present paper focuses on the design of a dedicated test bench to assess the effectiveness of different catalyst samples when immersed in hydrogen peroxide. To date, the apparatus has been used to study powdered silver and three oxides of manganese. The evaluation of an analytical technique for determining the observed decomposition rates is also presented. In addition to devising a quantitative method for assessing the efficacy of the candidate catalysts, some qualitative studies of proposed metallic catalysts, in the form of wires immersed in hydrogen peroxide, are also described. Of the catalyst materials tested so far, preliminary results suggest that dimanganese trioxide offers slightly better performance than both manganese dioxide and silver.
The direct synthesis of hydrogen peroxide over Au and Pd nanoparticles: A DFT study
Catalysis Today, 2020
Catalysts consisting of Au, Pd and their alloys have been shown to be active oxidation catalysts. These materials can use dioxygen or hydrogen peroxide as the oxidant with CO and activated organic molecules using O 2 (g) while more challenging cases, such as methane to partial oxygenates, relying on H 2 O 2. Although H 2 O 2 is a green oxidant, the incorporation of dioxygen greatly reduces overall cost and so there is an incentive to find new ways to reduce the reliance on H 2 O 2. In this study we use DFT calculations to discuss the direct synthesis of H 2 O 2 from H 2 (g) and O 2 (g) and use this understanding to identify the important surface species derived from dioxygen. We cover the adsorption of oxygen, hydrogen and water to model Au and Pd nanoclusters and the oxidation of the metals, since reduction of any oxides formed will consume H 2. We then turn to the production of a surface hydroperoxy species; the first step in the synthesis of H 2 O 2. This can occur via hydrogenation of O 2 (ads) with H 2 (ads) or via protonation of O 2 (ads) by solvent water. Both routes are found to be energetically reasonable, but the latter is likely to be favoured under experimental conditions.