Advances in the direct synthesis of hydrogen peroxide from hydrogen and oxygen

Effect of textual features and surface properties of activated carbon on the production of hydrogen peroxide from hydroxylamine oxidation

Herein, the textural features and surface properties of activated carbon were mediated by oxidation in the gas-phase or liquid-phase.

Generation of Hydroxyl Radicals in the Reaction of Dihydrogen with AuNbO4+ Cluster Cations

A molecular-level insight into the nature of reactive oxygen species involved in dihydrogen (H₂ ) dissociation is of great importance to understand gold catalysis. In this study, laser ablation generated and mass-selected AuNbO₄⁺ oxide cluster cations could dissociate H₂ in an ion-trap reactor. The reaction has been characterized by time-of-flight mass spectrometric experiments and density functional calculations. The lowest energy isomer of AuNbO₄⁺ contains two lattice oxygen (O^2- ) and one superoxide (O₂^.- ) species. The gold atom anchors the H₂ molecule in the first step and then delivers one hydrogen atom to the O^2- ion in H₂ dissociation. At the same time, O₂^.- is reduced into a peroxide unit that can accept the second hydrogen atom of H₂ with the generation of a hydroxyl radical as the main product. In this study, the important roles of the O₂^.- unit in the dissociation of H₂ have been identified.

Direct synthesis of hydrogen peroxide in water at ambient temperature

The direct synthesis of hydrogen peroxide (H2O2) from hydrogen and oxygen has been studied using an Au-Pd/TiO2 catalyst. The aim of this study is to understand the balance of synthesis and sequential degradation reactions using an aqueous, stabilizer-free solvent at ambient temperature. The effects of the reaction conditions on the productivity of H2O2 formation and the undesirable hydrogenation and decomposition reactions are investigated. Reaction temperature, solvent composition and reaction time have been studied and indicate that when using water as the solvent the H2O2 decomposition reaction is the predominant degradation pathway, which provides new challenges for catalyst design, which has previously focused on minimizing the subsequent hydrogenation reaction. This is of importance for the application of this catalytic approach for water purification.

Gas phase stabiliser-free production of hydrogen peroxide using supported gold-palladium catalysts

Hydrogen peroxide synthesis from hydrogen and oxygen in the gas phase is postulated to be a key reaction step in the gas phase epoxidation of propene using gold-titanium silicate catalysts. During this process H₂O₂ is consumed in a secondary step to oxidise an organic molecule so is typically not observed as a reaction product. We demonstrate that using AuPd nanoparticles, which are known to have high H₂O₂ synthesis rates in the liquid phase, it is possible to not only oxidise organic molecules in the gas phase but to detect H₂O₂ for the first time as a reaction product in both a fixed bed reactor and a pulsed Temporal Analysis of Products (TAP) reactor without stabilisers present in the gas feed. This observation opens up possibility of synthesising H₂O₂ directly using a gas phase reaction.

Crystal structure of a Pd4 carbonyl tri-phenyl-phosphane cluster [Pd4(CO)5(PPh3)4]·2C4H8O, comparing solvates

Attempts to synthesize Au-Pd heterometallic compounds from homonuclear palladium or gold complexes, [Pd(PtBu2)2] and [Au(PPh3)Cl] in a tetra-hydro-furan (THF) solution under a CO atmosphere resulted in a homonuclear Pd cluster, namely penta-kis-(μ-carbonyl-κ(2) C:C)tetra-kis-(tri-phenyl-phosphane-κP)tetrapalladium(5 Pd-Pd) tetra-hydro-furan disolvate, [Pd4(CO)5(C18H15P)4]·2C4H8O. The complex mol-ecule lies on a twofold rotation axis. The crystal structure is described in relation to the CH2Cl2 solvate previously determined by our group [Willocq et al. (2011 ▸). Inorg. Chim. Acta, 373, 233-242], and in particular to the desolvated structure [Feltham et al. (1985 ▸). Inorg. Chem. 24, 1503-1510]. It is assumed that the title compound transforms into the latter structure, upon gradual loss of solvent mol-ecules. In the title compound, the symmetry-unique THF solvent mol-ecule is linked to the complex mol-ecule by a weak C-H⋯O hydrogen bond. Contributions of disordered solvent molecules to the diffraction intensities, most likely associated with methanol, were removed with the SQUEEZE [Spek (2015). Acta Cryst. C71, 9-18] algorithm.

TiO2 nanoparticles vs. TiO2 nanowires as support in hydrogen peroxide direct synthesis: the influence of N and Au doping

Nitrogen doping is a new strategy to improve catalysts for H₂O₂ direct synthesis.

Depressing the hydrogenation and decomposition reaction in H2O2 synthesis by supporting AuPd on oxygen functionalized carbon nanofibers

The introduction of oxygen functionalities to the surface of CNFs depressed the hydrogenation and decomposition reaction during the synthesis of H₂O₂.

A review on research progress in the direct synthesis of hydrogen peroxide from hydrogen and oxygen: noble-metal catalytic method, fuel-cell method and plasma method

The direct synthesis of H₂O₂ from H₂ and O₂ using Pd catalyst, fuel cell and plasma methods have been reviewed systematically.

The use of modelling to understand the mechanism of hydrogen peroxide direct synthesis from batch, semibatch and continuous reactor points of view

Modelling is a powerful tool to understand the mechanism of H₂O₂ direct synthesis.

Characterisation of gold catalysts

Au-based catalysts have established a new important field of catalysis, revealing specific properties in terms of both high activity and selectivity for many reactions.

Catalysts for direct H2O2 synthesis taking advantage of the high H2 activating ability of Pt: kinetic characteristics of Pt catalysts and new additives for improving H2O2 selectivity

To develop efficient catalysts for the direct H₂O₂ synthesis from H₂ and O₂ by taking advantage of the high H₂ activating ability of Pt, kinetic studies of the H₂–O₂ reaction were performed using a Pt-PVP (polyvinylpyrrolidone) colloid and Pt supported on carbon (Pt/C) as catalysts, and new additives were explored.

The bifurcation point of the oxygen reduction reaction on Au–Pd nanoalloys

The oxygen reduction reaction is of major importance in energy conversion and storage. Controlling electrocatalytic activity and its selectivity remains a challenge of modern electrochemistry. Here, first principles calculations and analysis of experimental data unravel the mechanism of this reaction on Au–Pd nanoalloys in acid media. A mechanistic model is proposed from comparison of the electrocatalysis of oxygen and hydrogen peroxide reduction on different Au–Pd ensembles. A H₂O production channel on contiguous Pd sites proceeding through intermediates different from H₂O₂ and OOH^σ adsorbate is identified as the bifurcation point for the two reaction pathway alternatives to yield either H₂O or H₂O₂. H₂O₂ is a leaving group, albeit reduction of H₂O₂ to H₂O can occur by electrocatalytic HO–OH dissociation that is affected by the presence of adsorbed OOH^σ. Similarities and differences between electrochemical and direct synthesis from H₂ + O₂ reaction on Au–Pd nanoalloys are discussed.

Artificial photosynthesis for production of hydrogen peroxide and its fuel cells

The reducing power released from photosystem I (PSI) via ferredoxin enables the reduction of NADP(+) to NADPH, which is essential in the Calvin-Benson cycle to make sugars in photosynthesis. Alternatively, PSI can reduce O2 to produce hydrogen peroxide as a fuel. This article describes the artificial version of the photocatalytic production of hydrogen peroxide from water and O2 using solar energy. Hydrogen peroxide is used as a fuel in hydrogen peroxide fuel cells to make electricity. The combination of the photocatalytic H2O2 production from water and O2 using solar energy with one-compartment H2O2 fuel cells provides on-site production and usage of H2O2 as a more useful and promising solar fuel than hydrogen. This article is part of a Special Issue entitled Biodesign for Bioenergetics--The design and engineering of electronc transfer cofactors, proteins and protein networks, edited by Ronald L. Koder and J.L. Ross Anderson.

The influence of catalyst amount and Pd loading on the H2O2 synthesis from hydrogen and oxygen

Direct synthesis of H₂O₂: structure sensitivity in H₂O₂ production and structure insensitivity in the H₂O production were proved with a Pd/K2621 catalyst.