Design of green, safe, and sustainable process for the synthesis of hydrogen peroxide (H2O2) is a very important subject. Early reported processes, however, require hydrogen (H2) and palladium-based catalysts. Herein we propose a photocatalytic process for H2O2 synthesis driven by metal-free catalysts with earth-abundant water and molecular oxygen (O2) as resources under sunlight irradiation (λ>400 nm). We use graphitic carbon nitride (g-C3N4) containing electron-deficient aromatic diimide units as catalysts. Incorporating the diimide units positively shifts the valence-band potential of the catalysts, while maintaining sufficient conduction-band potential for O2 reduction. Visible light irradiation of the catalysts in pure water with O2 successfully produces H2O2 by oxidation of water by the photoformed valence-band holes and selective two-electron reduction of O2 by the conduction band electrons.

Sunlight-Driven Hydrogen Peroxide Production from Water and Molecular Oxygen by Metal-Free Photocatalysts†

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

Hydrogen peroxide (H2O2) is a highly effective, green oxidant that has found application in sectors ranging from the synthesis of fine chemicals and waste stream treatment to the extraction of precious metals and the bleaching of paper pulp and textiles. The growing demand for H2O2 has seen it become one of the 100 most important chemicals in the world. The direct synthesis of H2O2 from H2 and O2 has been a challenge for the scientific community for over 100 years and represents an attractive alternative to the current means of production. Herein we discuss the historical perspective of the direct synthesis process, the recent literature regarding catalyst design and the role of additives as well as the application of H2O2 as an in situ oxidant. We discuss the key problems that remain and conclude that although there has been progress with respect to the selectivity of hydrogen utilisation, there is a need to now concentrate on catalyst activity as the key remaining problem requiring a solution is the concentration of H2O2 that can be achieved especially in flow reactors.

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Recent Advances in the Direct Synthesis of H2O2

https://diva-portal.org/smash/get/diva2:693475/fulltext01.pdf

Engineering in direct synthesis of hydrogen peroxide: targets, reactors and guidelines for operational conditions

Research process on property and application of metal porous materials

Factors affecting catalytic destruction of H2O2 by hydrogenation and decomposition over Pd catalysts supported on activated carbon cloth (ACC)

The direct synthesis of hydrogen peroxide was investigated in a bench-scale continuous process using a novel microstructured reactor. This plate-type reactor was developed to offer favorable hydrodynamic and mass transfer conditions. Supported Pd catalyst on activated carbon cloths was employed. The experiments were conducted with hydrogen and oxygen using methanol as a solvent. Effects of process conditions, e.g. gas composition, gas and liquid flow rates, pressure and amount and composition of catalyst were studied. The promising results and plans for further development of the reactor and process concept are discussed.

Catalytic direct synthesis of hydrogen peroxide in a novel microstructured reactor

Activated carbon cloths (ACCs) were used as supports for Pd catalysts. The catalyst preparation was carried out by the impregnation method using acidic solution of palladium dichloride (PdCl2) as metal precursor. The effects of the oxidation state of the loaded metal, heat treatment of the catalysts in different atmosphere (H2, air) at different temperatures and surface chemistry of the support on the catalyst characterizations and the catalytic activities were investigated. Wet oxidation of ACC was done by nitric acid in order to induce oxygen-containing surface functional groups. Surface chemistry of the support and oxidation state of the metallic phase was investigated by means of XPS, TPD, SEM, DTA and TGA tests. Direct synthesis of hydrogen peroxide from H2 and O2 was performed batch wise in a stainless steel autoclave. The reactions were conducted under high pressure (38 bar) at 0 °C and methanol was used as reaction medium. The direct synthesis results showed that the oxygen-containing surface functional groups increase the selectivity of the catalysts by reducing the rate of water production. Existence of the oxidized state of Pd (PdO) also makes the catalyst more selective than the corresponding zerovalent state (Pd0). PdO affected on selectivity by increasing the rate of H2O2 production and reducing the amount of production of water, simultaneously.

Preparation and Study of Pd Catalysts Supported on Activated Carbon Cloth (ACC) for Direct Synthesis of H2O2 from H2 and O2

Promotional effects of Au in Pd–Au bimetallic catalysts supported on activated carbon cloth (ACC) for direct synthesis of H2O2 from H2 and O2

Prototype of structured microreactor plates with 300 μm deep flow channels was developed. Two plates with different structural elements, square and triangular, were used in the study. Flow behavior was investigated and the results showed excellent mixing behavior of gas and liquid phases. Hydrodynamic parameters and volumetric gas–liquid mass transfer coefficients were determined at various flow conditions. Gas holdup and the gas–liquid interfacial area were determined by an optical method using image processing software. Volumetric mass transfer coefficients were measured using nitrogen to strip oxygen from deionized water. The experimental results indicate a high mass transfer rate. Gas holdup and the total gas–liquid interfacial area were in the range of 20–45% and 2600–5600 m2 m−3, respectively. Volumetric mass transfer coefficients were as high as 1.1 s−1. An empirical correlation for the mass transfer coefficient was derived.

Davood Gudarzi

Papers

Factors affecting catalytic destruction of H2O2 by hydrogenation and decomposition over Pd catalysts supported on activated carbon cloth (ACC)

Catalytic direct synthesis of hydrogen peroxide in a novel microstructured reactor

Preparation and Study of Pd Catalysts Supported on Activated Carbon Cloth (ACC) for Direct Synthesis of H2O2 from H2 and O2

Promotional effects of Au in Pd–Au bimetallic catalysts supported on activated carbon cloth (ACC) for direct synthesis of H2O2 from H2 and O2

Hydrodynamics and mass transfer studies on a plate microreactor