Direct Synthesis Of Hydrogen Peroxide Research Articles

Masked second-shell sulfur coordinating atomically dispersed Pd on tin oxide boosts the direct synthesis of hydrogen peroxide

The coordination environments of isolated metals significantly influence the catalytic properties of materials. However, challenges persist in the precise modulation of these microenvironments. In this study, we achieved atomically dispersed Pd on sulfur-doped tin dioxide (SnO2) through the controlled oxidation of SnS2 nanosheets pre-loaded with single-atom Pd (Pd/SnS2). Our findings reveal that the synthesized catalyst features a central single-atom Pd, which coordinates with oxygen and tin in the first coordination shell and sulfur binding tin in the second shell. The coordination of isolated Pd with sulfur in the out-of-plane second shell layer enhances oxygen adsorption while inhibiting OO dissociation, thus directing hydrogen peroxide selectivity. This results in a higher productivity and durability of hydrogen peroxide compared to pristine Pd/SnS2 and traditional samples. This work presents an effective strategy to tailor and preserves the coordination micro-environment of central single-atom metals during catalytic reactions.

Properties of palladium-phosphorus catalysts supported on HZSM-5 zeolite in the direct synthesis of hydrogen peroxide

The properties of Pd/HZSM-5 and Pd–nP/HZSM-5 catalysts in direct synthesis and side processes of decomposition and hydrogenation of H2O2 under mild conditions in ethanol and aqueous-ethanol medium in the presence of an acid inhibitor were studied. Using HR-TEM, XRD and ICP MS methods, it was shown that as a result of modification with phosphorus, X-ray amorphous highly dispersed systems are formed, which represent structurally disordered solid solutions of phosphorus in palladium. The main reasons for the promoting effect of phosphorus on the yield of H2O2 are considered. It has been established that, along with phosphorus and acid modifiers, the use of a zeolite support in the H-form favors the inhibition of the side process of H2O2 decomposition.

Nest-shaped hollow-encapsulated Pd catalyst enhances the catalytic performance of hydrogen peroxide directly synthesizing from hydrogen and oxygen

A well-defined structural morphology can significantly construct a special catalytic micro-reaction environment to enhance the catalytic performance of Pd catalyst in the direct synthesis of hydrogen peroxide from hydrogen and oxygen (DSHP). In this study, SiO2 was used as a rigid template, PdCl2 as the Pd precursor, and dopamine hydrochloride (DA) as the carbon and nitrogen source to synthesize a nest-shaped hollow-encapsulated Pd catalyst named PdMulti@ONHCS. This catalyst was successfully constructed via high-temperature pyrolysis of poly dimethyl diallyl ammonium chloride (PDDA), which generated a blasting effect crucial for this formation. Characterization analysis, catalytic performance evaluation experiment, and molecular dynamics simulation were conducted to explore the structure-performance relationship of PdMulti@ONHCS catalyst in DSHP. Both experimental and simulation results consistently showed that the nest-shaped hollow structure of PdMulti@ONHCS catalyst created a distinctive catalytic microreactor environment with a spatial mass transfer constraint, which was not only conducive to adsorption and enrichment of H2 and O2 at Pd active sites to produce H2O2. In addition, the generated H2O2 can be desorbed from Pd active sites in time and rapidly diffused into the reaction solution, effectively inhibiting the dissociation of species containing OO bonds on the Pd surface, resulting in severe hydrogenation and decomposition side reactions, and improving H2O2 productivity and selectivity.

New Charged Interfaces for Energy Conversion and Catalysis

Charged interfaces are key areas for charge transfer and chemical reactions. Studying these interfaces at the microscopic level, especially in constructing and characterizing specific structures, understanding charge transfer, and managing chemical reactions, is crucial but challenging. Our work focuses on three innovative interface structures: solid/solid triboelectric, liquid/gas electrified, and solid/ultrathin heterojunction interfaces. We have achieved significant insights into the charge transfer mechanisms within these electrified systems and effectively controlled catalytic reactions at these interfaces.Key findings include: Development of new concepts for contact electrification and electrostatic-induced coupling at solid/solid interfaces, leading to novel applications in energy conversion and catalysis. We introduced the concept of mechanical-electric-catalytic reactions based on triboelectric interfaces and achieved direct synthesis of hydrogen peroxide through friction-catalysis under normal conditions.Effective control of reaction kinetics and selectivity in charged microdroplet liquid/gas electrified interfaces by adjusting parameters like droplet evaporation rates and electric field characteristics. This approach led to efficient production of hydrogen peroxide and selective conversion of carbon dioxide.Precise atomic-level construction and sub-nanometer characterization of solid/ultrathin heterojunction interfaces, exemplified by gold/graphene interfaces. This included the development of a gold/ultrathin palladium/single-layer ruthenium structure, enabling in-depth study of hydroxylation reactions and the influence of palladium interlayers on ruthenium's catalytic efficiency.

Exploring the key role of electronic effects in Pd catalysts supported on Ni-modified N-doped porous carbon for direct synthesis of H2O2 under atmospheric pressure

Developing high-performance catalysts for direct synthesis of hydrogen peroxide (H2O2; DSHP) remains challenging. The paper proposes a strategy to optimize Pd catalysts by enriching Ni-modified N-doped porous carbon. The theoretical studies indicate that Ni modulates the electronic structure of Pd through charge transfer and strain effects, effectively reducing the adsorption energy of reaction intermediates. Furthermore, the Crystal Orbital Hamilton Population (COHP) analysis demonstrated that the energy-integrated COHP (ICOHP) of the OO bonds in O2* (* denotes the adsorbed state), OOH*, and HOOH* were positively correlated with dissociation activation energies and negatively correlated with hydrogenation activation energies. The modulation of the electronic structure of Pd by Ni reduces the hydrogenation activation energies of O2* and OOH* and increases the dissociation activation energies of O2*, OOH*, and HOOH*, thereby enhancing the selectivity and productivity of H2O2. The experimental results aligned with the theoretical predictions, showcasing that the optimized Pd-Ni7.5/NPCs catalyst exhibited remarkable H2O2 selectivity and productivity of 70.5 % and 230.31 mol kgcat-1·h-1, respectively, surpassing the performance of Pd/NPCs (47.1 % and 52.3 mol kgcat-1·h-1). This study offers profound insights into the crucial role of electron effects in DSHP using nickel-modified palladium catalysts, providing strong evidence into the design and optimization of Pd catalysts.

Reversible hydrogen spillover induced by Brønsted acid for accelerating direct synthesis of hydrogen peroxide

Supported PdAu bimetallic nanoparticles have been developed for the direct synthesis of H2O2 (DSHP). However, to date, the dilute H2 streams necessary to avoid potential risks of explosion limits the attainable product concentrations of H2O2. Here, a series of silicon-modified Al2O3 (SixAl) were synthesized for loading PdAu bimetallic nanoparticles. The H2 consumption turnover frequency (TOF) and H2O2 formation TOF show a volcano trend with the silica content, where PdAu/Si5.6Al exhibits the best H2 consumption TOF and H2O2 formation TOF (11259.3 and 1995.2 h−1). Silica on the surface of Al2O3 is identified as Brønsted (B) acid site. The increase of B acid sites density accelerates the H2 conversion into H atoms, thereby boosting H2O2 formation process. The adsorption and dissociation of H2 into atomic H at B acid sites would spill across the support to PdAu nanoparticles reversely. The reversed hydrogen spillover effect induced by B acid site accounts for enhanced H2 conversion and H2O2 productivity for PdAu/SixAl.

Deposition of Pd, Pt, and PdPt Nanoparticles on TiO2 Powder Using Supercritical Fluid Reactive Deposition: Application in the Direct Synthesis of H2O2.

In this study, we investigated the catalytic properties of mono- and bimetallic palladium (Pd) and platinum (Pt) nanoparticles deposited via supercritical fluid reactive deposition (SFRD) on titanium dioxide (TiO2) powder. Transmission electron microscopy analyses verified that SFRD experiments performed at 353 K and 15.6 MPa enabled the deposition of uniform mono- and bimetallic nanoparticles smaller than 3 nm on TiO2. Electron-dispersive X-ray spectroscopy demonstrated the formation of alloy-type structures for the bimetallic PdPt nanoparticles. H2O2 is an excellent oxidizing reagent for the production of fine and bulk chemicals. However, until today, the design and preparation of catalysts with high H2O2 selectivity and productivity remain a great challenge. The focus of this study was on answering the questions of (a) whether the catalysts produced are suitable for the direct synthesis of hydrogen peroxide (H2O2) in the liquid phase and (b) how the metal type affects the catalytic properties. It was found that the metal type (Pd or Pt) influenced the catalytic performance strongly; the mean productivity of the mono- and bimetallic catalysts decreased in the following order: Pd > PdPt > Pt. Furthermore, all catalysts prepared by SFRD showed a significantly higher mean productivity compared to the catalyst prepared by incipient wetness impregnation.

Identifying Pd9OX as the optimum catalyst for the direct synthesis of H2O2 through microkinetic modeling with coverage effects

Identifying efficient active sites for the direct synthesis of hydrogen peroxide over Pd-based catalysts has been a subject of considerable debate. In this study, we employ particle swarm optimization method and density functional theory to explore the H2O2 synthesis mechanism on Pd, PdO, and the partially oxidized surface (Pd9OX). A comprehensive mechanism for Pd9OX is elucidated, and subsequent coverage-dependent kinetic analysis allows for a quantitative assessment of catalytic performance at the interphase. Our findings conclusively establish that the interphase between Pd and PdO represents the optimal active site. Phase diagram analysis further aids in determining stable structures under reaction conditions. At 298.15 K and under oxygen balance, the Pd9O6 surface remains stable throughout the reaction, demonstrating high activity and selectivity. This work underscores the significance of the interphase in comprehending catalytic performance and unveils promising avenues for optimizing catalyst performance by controlling reaction conditions and surface composition.

In Situ Performance Monitoring of Electrochemical Oxygen and Hydrogen Peroxide Sensors in an Additively Manufactured Modular Microreactor.

Miniaturized and microstructured reactors in process engineering are essential for a more decentralized, flexible, sustainable, and resilient chemical production. Modern, additive manufacturing methods for metals enable complex reactor-geometries, increased functionality, and faster design iterations, a clear advantage over classical subtractive machining and polymer-based approaches. Integrated microsensors allow online, in situ process monitoring to optimize processes like the direct synthesis of hydrogen peroxide. We developed a modular tube-in-tube membrane reactor fabricated from stainless steel via 3D printing by laser powder bed fusion of metals (PBF-LB/M). The reactor concept enables the spatially separated dosage and resaturation of two gaseous reactants across a membrane into a liquid process medium. Uniquely, we integrated platinum-based electrochemical sensors for the online detection of analytes to reveal the dynamics inside the reactor. An advanced chronoamperometric protocol combined the simultaneous concentration measurement of hydrogen peroxide and oxygen with monitoring of the sensor performance and self-calibration in long-term use. We demonstrated the highly linear and sensitive monitoring of hydrogen peroxide and dissolved oxygen entering the liquid phase through the membrane. Our measurements delivered important real-time insights into the dynamics of the concentrations in the reactor, highlighting the power of electrochemical sensors applied in process engineering. We demonstrated the stable continuous measurement over 1 week and estimated the sensor lifetime for months in the acidic process medium. Our approach combines electrochemical sensors for process monitoring with advanced, additively manufactured stainless steel membrane microreactors, supporting the power of sensor-equipped microreactors as contributors to the paradigm change in process engineering and toward a greener chemistry.

Properties of Palladium-Phosphorus Catalysts Supported on HZSM-5 Zeolite in Direct Synthesis of Hydrogen Peroxide

Properties of Palladium-Phosphorus Catalysts Supported on HZSM-5 Zeolite in Direct Synthesis of Hydrogen Peroxide

New Design PdNi Heterogeneous Nanocatalysts for the Direct Synthesis of Hydrogen Peroxide

Hydrogen peroxide (H2O2) is a widely used chemical as an eco-friendly oxidizing agent, with water being the only byproduct of oxidation in applications like bleaching pulp and paper, making electronic semiconductors, chemical and detergent synthesis, and wastewater treatment. The direct synthesis approach is preferred to provide the environmentally friendly production of H2O2 for market requirements. Bimetallic PdNi nanocatalysts were chosen for this study because of their catalytic activity and the structural characteristics of the material system. First, for the development of order-structured bimetallic PdNi nanocatalysts based on mesoporous carbon template after hydrogen-assisted heat treatment at 750∘C. The transformation of the disordered structure into ordered intermetallically structured PdNi alloys with higher alloying extents was confirmed by X-ray absorption spectroscopy (XAS) and high-resolution transition electron microscopy (HR-TEM). Then, to improve the oxygen oxidation reaction, two-electron pathway selectivity was used by TiO2-C as a support-ordered structure material to facilitate strong metal-support interactions. XAS and X-ray photoelectron spectra (XPS) techniques show more clear evidence of metal-support interactions with electron transfer from defects in the TiO2-C support to the ordered alloyed PdNi nanocatalysts, resulting in record productivity and selectivity of H2O2 production at ambient conditions. The results demonstrated in this study will enlighten a reliable design of new heterogeneous nanocatalysts with ordered structure. Electron transfer between hybrid support and active sites can clarify the catalytic behavior and prompt further research during the direct synthesis of hydrogen peroxide.
 Keywords: hydrogen peroxide, direct synthesis, heterogeneous nanocatalysts PdNi, TiO2-C

Structural Stability Study of Nanocluster PD-based Catalyst

The rapidly growing population in the world demands an increase in the support of human life by providing massive production of food and medicine. As a result, the catalyst used in the production of the material plays a key role leading to intensive research. Synthesis of nanomaterials is becoming an important way to discover new catalysts by changing sizes and combining two or more metals on the nanoscale. Pd-based catalysts are well-known catalysts such as Pd-Pt, Pd-H, and Pd-Au for many chemical reactions such as the direct synthesis of hydrogen peroxide. Therefore, the provision of nanocluster bimetallic catalysts offers more benefits such as the rearrangement of surfaces to suit characteristics and lower material costs. However, the stability of the catalyst challenges researchers beyond reactivity and selectivity. In this paper, we predict the structural stability of Pd-based catalysts using a density functional theory approach. We use the 38-atom model in the M6@Pd32 core shell, where M is Hg, Pt, Au, Cu, Ni, Cu, Zn, Ag, Pd, and Cd, Pt. We prepared and investigated a series of structures such as truncated octahedral (TO) and polyhedral (PH) by calculating the excess energy. Based on our calculations and placing the monometallic Pd38 nanocluster as a reference, the TO structure is more stable than that of PH. The Zn6@Pd32 system showed the most stable followed by Cd6@Pd32 and Hg6@Pd32 was the worst.
 Keywords: structural stability, core-shell, nanocluster, Pd-based catalyst

Radical reactivity of mesoporous sulfonic polydivinylbenzene as the catalytic support in the direct synthesis of hydrogen peroxide and its role in the formation of palladium hydrides

The direct synthesis of H2O2 is nowadays a hotspot in heterogeneous catalysis. The reaction is promoted by Pd nanoparticles supported on a porous material, strongly affecting the catalytic performance. Nanostructured Pd supported on ion-exchange resins shows remarkable catalytic activity, as compared to catalysts supported on inorganic materials. Novel catalysts supported by a highly accessible cross-linked polymer have been developed, by using a mesoporous form of polydivinylbenzene (pDVB). Different sulfonation procedures lead to different morphology and reactivity of the supports, hence to different performances of palladium catalysts supported thereby. XRD suggests the formation of palladium hydride during the metal precursor reduction with H2. This phase is stable under laboratory conditions for several weeks, but its catalytic role, if any, also depends on other conditions, such as the presence of sulfonic groups. EPR of the spent catalysts points out radical species, suggesting the participation of pDVB in the formation of H2O2.

Benzotrithiophene-based covalent organic frameworks as efficient catalysts for artificial photosynthesis of H2O2 in pure water

Direct synthesis of hydrogen peroxide (H2O2) using oxygen and water through the photocatalytic route is a prospective approach for the on-site production of H2O2. However, the limited varieties of photocatalytic sites and ambiguous structure-active relationship impede the development of environmentally friendly technology. Herein, we report a active compound (benzotrithiophene, BTT) for the photosynthesis of H2O2 using oxygen and water, and design four benzotrithiophene-based 2D covalent organic frameworks (BTT-COFs) linked with aromatic amines linkers. Significant enhancement in photocatalytic activity has been observed via the introduction of BTT struct into 2D COFs. The high crystallinity of COFs increases the visible light absorption ability and photostability of BTT. The suitable distance of BTT struct in COFs and the construction of donor–acceptor (D-A) structure further promote the carrier generation and transfer. The COF-BTT-TAPT exhibited the highest H2O2 production rate of 620 μmol g−1 h−1. Mechanism investigation experiments have given the validation that BTT-COFs efficiently reduce oxygen in pure water to form H2O2 under visible-light irradiation. This work paves a revolutionary way for designing and fabricating high-performance metal-free photocatalysts for visible-light-driven H2O2 production.

Recent advances in tailoring the microenvironment of Pd-based catalysts for enhancing the performance in the direct synthesis of hydrogen peroxide.

Hydrogen peroxide (H2O2) is a valuable clean chemical, which is widely applied in modern industrial production. In the past few decades, H2O2 has been mainly produced industrially by the anthraquinone method, but the process is complicated and energy consuming, which is only economical for large-scale production and is harmful to the environment. The direct synthesis of H2O2 is considered a promising process to replace the anthraquinone method with high atomic economy, no hazardous by-products, and convenient operation, which has attracted much attention. In this review, we systematically present the recent advances in tuning the microenvironment of Pd-based catalysts for enhancing the performance of the direct synthesis of H2O2, including the modulation of active sites and support, from the viewpoint of the reaction mechanism. Finally, a summary and perspective on the most pressing issues and associated untapped research prospects with the direct synthesis of H2O2 are discussed. The purpose of this review is to provide in-depth insights and guidelines to promote the development of novel catalysts for the direct synthesis of H2O2.

Progress and perspectives of Pd-based catalysts for direct synthesis of hydrogen peroxide

In this work, the theoretical basis, catalyst design and in situ application of DSHP are comprehensively summarized. It has certain guiding significance for the design of future catalysts.

The First Application of Palladium–Phosphorus Catalysts in the Direct Synthesis of Hydrogen Peroxide: Reasons for the Promoting Action of Phosphorus

The First Application of Palladium–Phosphorus Catalysts in the Direct Synthesis of Hydrogen Peroxide: Reasons for the Promoting Action of Phosphorus

Supercritical deposition of mono- and bimetallic Pd and Pt on TiO[formula omitted] coated additively manufactured substrates for the application in the direct synthesis of hydrogen peroxide

In this study we investigated the properties of mono- and bimetallic Pd and Pt deposited via supercritical fluid reactive deposition (SFRD) on TiO2 coated additively manufactured substrates. The focus of this work lies on the suitability of these catalysts for the direct synthesis of H2O2 in the liquid phase. All catalysts produced showed a high activity towards the desired reaction, derived from high productivities towards the desired product. Thereby, the productivity of the different catalysts decreased in the following order: Pd = PdPt > Pt. In agreement with literature, an increase of the Pd loading from 1 to 2 wt.-% led to a decrease in the productivity. Resulting from comparison with productivities from literature, this method indicates a high suitability of the SFRD method for the suggested application. Due to the easy and eco-friendly nature of this deposition method the catalyst production process can be intensified.

The First Application of Palladium–Phosphorus Catalysts in the Direct Synthesis of Hydrogen Peroxide: Reasons for the Promoting Action of Phosphorus

The main reasons for the promoting effect of phosphorus on the properties of Pd–P/ZSM-5 palladium catalysts in the direct synthesis of H2O2 from H2 and O2 under mild conditions are considered based on data from X-ray photoelectron spectroscopy (XPS), X-ray powder diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and inductively coupled plasma mass spectrometry (ICP MS). It is shown that the introduction of phosphorus into the composition of the catalyst affects the dispersity, the electronic state of palladium in the surface layer, and the surface concentration of phosphate and phosphite ions. An increase in the H2O2 yield is favored by an increase in the dispersion of Pd–P-catalysts, inhibition of the side process of H2O2 decomposition by surface phosphate and phosphite ions, and a decrease in the solubility of hydrogen in solid solutions of phosphorus in palladium.

Electronic regulation and hydrophobicity improvement of the palladium active site by ionic liquid to achieve high selectivity direct synthesis of hydrogen peroxide

Electronic regulation and hydrophobicity improvement of the palladium active site by ionic liquid to achieve high selectivity direct synthesis of hydrogen peroxide