Catalytic direct synthesis of hydrogen peroxide in a novel microstructured reactor

Ratchananusorn, Warin; Gudarzi, Davood; Турунен, Илкка

doi:10.1016/j.cep.2014.01.005

Cited by 10 publications

(6 citation statements)

References 22 publications

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Section: Toc Graphics: Introductionmentioning

confidence: 99%

“…The challenging aspects of the reaction also led to novel reaction engineering concepts aimed at enhancing process control and boosting H 2 O 2 productivity. Many types of reactors, including trickle beds, microreactors, and membrane reactors, have been studied in order to increase productivity in a continuous flow process. − It should be noted that while Hutchings et al reported that a Pd–Au catalyst retained >98% H 2 O 2 selectivity after 98 h of reaction in batch operation, the long-term stability of a catalyst producing H 2 O 2 with sufficient selectivity and productivity is still a primary concern for continuous flow operation . The reaction mechanism of the direct synthesis is usually studied by activity tests in autoclaves. − 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 .…”

Section: Introductionmentioning

confidence: 99%

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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

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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.

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Section: Toc Graphics: Introductionmentioning

confidence: 99%

Section: 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

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“…A variety of studies have been performed to synthesize hydrogen peroxide directly from hydrogen and oxygen with microfluidic reactors , where hydrogen and oxygen can be mixed within the explosion regime, promoting reaction productivity and selectivity. The reactor type, solvent, catalyst component, loading method, as well as the yield and selectivity have been summarized in Table .…”

Section: Reasons For Enhanced Safety: Superior Performance Of Microrementioning

confidence: 99%

Application of microfluidics technology in chemical engineering for enhanced safety

et al. 2015

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The unique virtues of microfluidic technology have earned it an important place in a variety of chemical engineering applications. Among advantages including improved selectivity or yield, one crucial yet often neglected one is enhanced safety. Herein, we have critically reviewed latest progress in the study of using microreactors to reduce associated risk when performing experiments. Related research results have been carefully selected and categorized based on the major consideration to employ microfluidic technology, for example, fast heat/mass transfer, tolerance to high pressure, and confinement of toxic materials. Frontiers and remaining challenge of the field have been addressed at the end of this review as well.

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“…Biasi et al studied different catalytic systems in a trickle bed reactor using diluted gas mixtures at a pressure of 10 bar [41][42][43]. Microchannel set ups were used by different groups since the small inner dimensions on the one hand prevent explosions and thereby explosive mixtures can be utilized, and on the other hand, they decrease liquid diffusion pathways by forcing favorable flow patterns [44][45][46][47][48][49][50][51][52][53]. Membrane reactors are especially interesting since gas phase contact of H 2 and O 2 can be prevented by introducing one or both reactants through a membrane into the liquid solvent containing the catalyst [54][55][56][57].…”

Section: Introductionmentioning

confidence: 99%

“…Exp.-Nr. :[49][50], diamonds: 3 × 0.125 mm deep microchannel, 180 µm Nafion ® membrane, 5 mM NaBr (Table 1 Exp.-Nr. : 46-48), circles: 0.5 mm deep microchannel, 30 µm Nafion ® membrane, 5 mM NaBr, 4 mM H 3 PO 4 , 25 mM H 2 SO 4 (Table 1 Exp.-Nr.…”

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Experimental Evaluation of a Membrane Micro Channel Reactor for Liquid Phase Direct Synthesis of Hydrogen Peroxide in Continuous Flow Using Nafion® Membranes for Safe Utilization of Undiluted Reactants

2018

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In recent years, various modular micro channel reactors have been developed to overcome limitations in challenging chemical reactions. Direct synthesis of hydrogen peroxide from hydrogen and oxygen is a very interesting process in this regard. However, the complex triphasic process (gaseous reactants, reaction in liquid solvent, solid catalyst) still holds challenges regarding safety, selectivity and productivity. The membrane micro reactor system for continuous liquid phase H2O2 direct synthesis was designed to reduce safety issues by separate dosing of the gaseous reactants via a membrane into a liquid-flow channel filled with a catalyst. Productivity is increased by enhanced mass transport, attainable in micro channels and by multiple re-saturation of the liquid with the reactants over the length of the reaction channel. Lastly, selectivity is optimized by controlling the reactant distribution. The influence of crucial technical features of the design, such as micro channel geometry, were studied experimentally in relationship with varying reaction conditions such as residence time, pressure, reactant ratio and solvent flow rate. Successful continuous operation of the reactor at pressures up to 50 bars showed the feasibility of this system. During the experiments, control over the reactant ratio was found to be crucial in order to maximize product yield. Thereby, yields above 80% were achieved. The results obtained are the key elements for future development and optimization of this reactor system, which will hopefully lead to a breakthrough in decentralized H2O2 production.

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Catalytic direct synthesis of hydrogen peroxide in a novel microstructured reactor

Cited by 10 publications

References 22 publications

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

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

Application of microfluidics technology in chemical engineering for enhanced safety

Experimental Evaluation of a Membrane Micro Channel Reactor for Liquid Phase Direct Synthesis of Hydrogen Peroxide in Continuous Flow Using Nafion® Membranes for Safe Utilization of Undiluted Reactants

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