Effect of low hydrogen to palladium molar ratios in the direct synthesis of H2O2 in water in a trickle bed reactor

Huerta, Irene; Biasi, Pierdomenico; García-Serna, Juan; Cocero, M. J.; Mikkola, Jyri‐Pekka; Salmi, Tapio

doi:10.1016/j.cattod.2014.04.012

Cited by 14 publications

(10 citation statements)

References 24 publications

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“…The fundamental aspects of the CDS process have been reviewed recently, but many issues that concern the reaction mechanism still remain unclear because of the complexity of the three‐phase system and the reaction network (Scheme ). Metallic Pd is the most active catalyst for this reaction and is applied generally in a supported form.…”

Section: Introductionmentioning

confidence: 99%

Influence of Metal Precursors and Reduction Protocols on the Chloride‐Free Preparation of Catalysts for the Direct Synthesis of Hydrogen Peroxide without Selectivity Enhancers

et al. 2016

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Different metal precursors and reducing agents were applied in the preparation of 1 wt % Pd catalysts supported on commercial ion‐exchange resin (Lewatit K2621) and used in the direct synthesis of H2O2. The catalysts were characterized by using TEM and their performance was evaluated in the direct synthesis of H2O2 (in a batch and semi‐batch reactor) to investigate the relationship between the catalyst preparation methods, morphology, and catalytic performance. As expected, both the choice of the Pd precursor and the reduction conditions had a strong influence on the size and size distribution of the resulting supported nanostructured metal nanoparticles and, consequently, on the catalytic performance. The best combination of metal precursor and reduction agent was [Pd(NH3)4]SO4 reduced with hydrogen. This catalyst had the largest average size of the Pd nanoparticles and the broadest size distribution.

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Section: Introductionmentioning

confidence: 99%

Influence of Metal Precursors and Reduction Protocols on the Chloride‐Free Preparation of Catalysts for the Direct Synthesis of Hydrogen Peroxide without Selectivity Enhancers

et al. 2016

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“…Cheap H2O2 offers the potential to pave the way to a cleaner and more sustainable industrial oxidation chemistry 2 as it generates only water as by-product in contrast to chlorinated oxidizers. Despite its advantages, H2O2 is still not economically competitive compared to other oxidizers 3 which is related to the anthraquinone process 4 , the current standard for industrial H2O2 production. This process comprises a complex multi-stage process which is only economical in large-scale plants 5 .…”

Section: Introductionmentioning

confidence: 99%

Effect of Selectivity Enhancers on the Structure of Palladium during High-Pressure Continuous-Flow Direct Synthesis of Hydrogen Peroxide in Ethanol

et al. 2021

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A potentially green process to produce hydrogen peroxide (H2O2) is its direct synthesis from molecular hydrogen and oxygen. Still, the lack of mechanistic understanding of the reaction impedes a knowledge-based catalyst design for improved selectivity and stability. In this study, we employed X-ray absorption spectroscopy (XAS) to obtain structural information on a titania-supported palladium (Pd) catalyst under H2O2 synthesis conditions. The study focuses on the effect of the liquid-phase H2:O2 ratio between 0.67 and 3 and solvent composition under industrially relevant conditions, that is ethanol with and without H2SO4 and NaBr as selectivity enhancers at 40 bar. The X-ray near-edge structure of the absorption spectra (XANES) and the extended X-ray absorption fine structure (EXAFS) revealed that ethanol fully reduces Pd nanoparticles, even when saturated with oxygen. Oxygen presence at the Pd surface could only be suspected based on its small contribution to the EXAFS signal. A palladium hydride phase is detected under stoichiometric conditions due to lattice expansion. Addition of H2SO4 causes Pd lattice expansion and an increased yield at stoichiometric conditions. Further addition of bromide did not lead to any significant change in catalyst state and activity.

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“…Although H 2 O 2 itself is an eco-friendly chemical, the way it is produced is not an ecologically sustainable process from the green chemistry viewpoint. Currently, the major production of H 2 O 2 is done through the so-called anthraquinone auto-oxidation (AO) process, which alone is responsible for around 95% of the overall H 2 O 2 production [ 6 , 7 , 8 ]. The process is complex, requires a lot of energy, and produces toxic, organic waste [ 3 , 5 ].…”

Section: Introductionmentioning

confidence: 99%

Microsensor Electrodes for 3D Inline Process Monitoring in Multiphase Microreactors

Urban

Sundaram

Kieninger

et al. 2020

Sensors

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We present an electrochemical microsensor for the monitoring of hydrogen peroxide direct synthesis in a membrane microreactor environment by measuring the hydrogen peroxide and oxygen concentrations. In prior work, for the first time, we performed in situ measurements with electrochemical microsensors in a microreactor setup. However, the sensors used were only able to measure at the bottom of the microchannel. Therefore, only a limited assessment of the gas distribution and concentration change over the reaction channel dimensions was possible because the dissolved gases entered the reactor through a membrane at the top of the channel. In this work, we developed a new fabrication process to allow the sensor wires, with electrodes at the tip, to protrude from the sensor housing into the reactor channel. This enables measurements not only at the channel bottom, but also along the vertical axis within the channel, between the channel wall and membrane. The new sensor design was integrated into a multiphase microreactor and calibrated for oxygen and hydrogen peroxide measurements. The importance of measurements in three dimensions was demonstrated by the detection of strongly increased gas concentrations towards the membrane, in contrast to measurements at the channel bottom. These findings allow a better understanding of the analyte distribution and diffusion processes in the microreactor channel as the basis for process control of the synthesis reaction.

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Effect of low hydrogen to palladium molar ratios in the direct synthesis of H2O2 in water in a trickle bed reactor

Cited by 14 publications

References 24 publications

Influence of Metal Precursors and Reduction Protocols on the Chloride‐Free Preparation of Catalysts for the Direct Synthesis of Hydrogen Peroxide without Selectivity Enhancers

Influence of Metal Precursors and Reduction Protocols on the Chloride‐Free Preparation of Catalysts for the Direct Synthesis of Hydrogen Peroxide without Selectivity Enhancers

Effect of Selectivity Enhancers on the Structure of Palladium during High-Pressure Continuous-Flow Direct Synthesis of Hydrogen Peroxide in Ethanol

Microsensor Electrodes for 3D Inline Process Monitoring in Multiphase Microreactors

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