Direct synthesis of hydrogen peroxide using concentrated H2 and O2 mixtures in a wall-coated microchannel – kinetic study

Paunovic, V.; Schouten, J.C.; Nijhuis, T.A.

doi:10.1016/j.apcata.2015.07.029

Cited by 20 publications

(18 citation statements)

References 46 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The proposed model is based on steady‐state H 2 O 2 formation rate measurements conducted in our group across a wide range of H 2 (10–1,000 kPa) and O 2 (5–1,000 kPa) pressures as well as H 2 O 2 hydrogenation rates measured at varying H 2 O 2 concentrations (0.1–1 mM) and H 2 pressures (25–400 kPa) in a plug flow reactor in purely aqueous solvents (described elsewhere) . Equation ) is consistent with these previous observations for H 2 O 2 formation and hydrogenation rates obtained at low H 2 (10–60 kPa) and O 2 (5–25 kPa) pressures and also agree with results reported in purely aqueous systems by Lawal and coworkers on Pd–SiO 2 in the presence of 10 ppm NaBr, and by Nijhuis and group on Pd 2 Au–SiO 2 …”

Section: Resultssupporting

confidence: 82%

Form of the catalytically active Pd species during the direct synthesis of hydrogen peroxide

Priyadarshini

Flaherty

2019

AIChE Journal

View full text Add to dashboard Cite

Direct synthesis of H 2 O 2 could produce H 2 O 2 at lower cost than the Riedl-Pfleiderer process, which would enable the broader use of H 2 O 2 for industrial oxidations. The addition of inorganic acids and halides to the solvent increase H 2 O 2 selectivities on Pd nanoparticles but also dissolve Pd and produce dynamic mixtures of complexes including heterogeneous (Pd 0 ) and homogeneous (Pd 2+ ) species, any of which may contribute to H 2 O 2 formation. We combine kinetic measurements and in operando UV-vis spectroscopy to determine how H 2 O 2 rates and selectivities depend on concentrations of these forms of Pd. Introducing HCl to the solvent increases the concentration of Pd 2+ complexes by oxidizing Pd 0 nanoparticles. The rates of primary H 2 O 2 formation and H 2 O 2 selectivities do not depend directly on the population of the Pd 2+ species for catalysts tested in water or methanol. These results suggest that Pd nanoparticles form H 2 O 2 and detectable homogeneous complexes do not act as catalysts.

show abstract

Section: Resultssupporting

confidence: 82%

Form of the catalytically active Pd species during the direct synthesis of hydrogen peroxide

Priyadarshini

Flaherty

2019

AIChE Journal

View full text Add to dashboard Cite

show abstract

“…reported that a Pd-Au catalyst retained >98 % H2O2 selectivity after 98 hours of reaction in batch operation [27], long term stability of a catalyst producing H2O2 with sufficient selectivity and productivity is still a primary concern for continuous flow operation [28]. The reaction mechanism of the direct synthesis is usually studied by activity tests in autoclaves [29][30][31]. However, it is difficult to derive aspects of the reaction mechanism because of the complex transport phenomena in the triphasic gas-liquid-solid system overshadowing the intrinsic kinetics [2].…”

Section: Toc Graphics: Introductionmentioning

confidence: 99%

Revealing the Structure and Mechanism of Palladium during Direct Synthesis of Hydrogen Peroxide in Continuous Flow Using Operando Spectroscopy

Selinsek¹,

Deschner²,

Doronkin

et al. 2018

ACS Catal.

113

View full text Add to dashboard Cite

The direct synthesis of H2O2 is a dream reaction in the field of selective oxidation and green chemical synthesis. However, the unknown active state of the catalyst and the lack of a defined catalytic mechanism preclude the design and optimization of suitable catalysts and reactor setups. Here direct synthesis of H2O2 over Pd-TiO2 in water was investigated in a continuous flow reactor setup utilizing undiluted oxygen and hydrogen to increase aqueous phase concentrations safely at ambient temperature and a pressure of 10 bars. In this experiment operando X-ray Absorption Spectroscopy (XAS) and online flow injection analysis for photometric quantification of H2O2 were combined to build catalyst structure-activity relationships in direct H2O2 synthesis. XAS at the Pd K absorption edge was used to observe oxidation state and local Pd structure together with H2O2 production for three reactant ratio (H2/O2) regimes: hydrogen rich (> 2), hydrogen lean (< 0.5) and balanced (0.5-2). During H2O2 production, oxygen was only found adsorbed on the surface of Pd nanoparticles and hydrogen was found dissolved in bulk palladium hydride (α-phase) indicating a reaction of surface oxygen with lattice hydrogen to form hydrogen peroxide. Under hydrogen rich conditions, formation of β-phase palladium hydride was found to coincide with zero H2O2 yield. This constitutes an operando study of direct H2O2 synthesis under elevated partial pressures of H2 and O2 in continuous flow. The results obtained will aid in rational design of future catalysts and optimization of process parameters, bringing the concept of a viable, efficient process for H2O2 synthesis one step closer to reality.

show abstract

“…End users of hydrogen peroxide though typically require a concentration in the range of 1-10 wt% and so this dilution represents an additional cost. 4 Furthermore, this process requires big industrial plants, wastewater treatment, and produces a large amount of by-products. For these reasons, the cost of hydrogen peroxide is relatively high, limiting its industrial large-scale use.…”

Section: Introductionmentioning

confidence: 99%

“…Selinsek et al 20 developed a novel intensified suspensionflow membrane microreactor system for the direct synthesis of hydrogen peroxide, and other works also have developed this kind of technology. 1,4,12 The aforementioned idea seems useful and inspiring, but all in all, it becomes less enriching if a model including the kinetics and mass-transfer limitations is not considered. As the previous mentioned studies modeled the direct synthesis process, so our work would like to make a remarkable imprint in this overview.…”

Section: Introductionmentioning

confidence: 99%

A mathematical model of a slurry reactor for the direct synthesis of hydrogen peroxide

et al. 2019

View full text Add to dashboard Cite

show abstract

Direct synthesis of hydrogen peroxide using concentrated H2 and O2 mixtures in a wall-coated microchannel – kinetic study

Cited by 20 publications

References 46 publications

Form of the catalytically active Pd species during the direct synthesis of hydrogen peroxide

Form of the catalytically active Pd species during the direct synthesis of hydrogen peroxide

Revealing the Structure and Mechanism of Palladium during Direct Synthesis of Hydrogen Peroxide in Continuous Flow Using Operando Spectroscopy

A mathematical model of a slurry reactor for the direct synthesis of hydrogen peroxide

Contact Info

Product

Resources

About