Electrochemical multisensor system for monitoring hydrogen peroxide, hydrogen and oxygen in direct synthesis microreactors

Urban, Sebastian; Weltin, Andreas; Flamm, Hubert; Kieninger, Jochen; Deschner, Benedikt J.; Kraut, Manfred; Dittmeyer, Roland; Urban, G.

doi:10.1016/j.snb.2018.07.014

Cited by 18 publications

(24 citation statements)

References 62 publications

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“…Since the liquid phase contains a fixed sodium bromide concentration (4 mM), an on-plug silver/silver bromide (Ag/AgBr) electrode with a diameter of 500 μM is used as pseudo-reference electrode. The deposition of the Ag/AgBr electrode was carried out by anodic bromination of the silver wire as described in more detail in our prior work [ 21 ].…”

Section: Methods and Experimentalmentioning

confidence: 99%

“…Figure 2 shows a schematic overview of the fabrication process of the sensor plugs. A pHEMA-based hydrogel membrane, as reported previously [ 21 ], was applied to the electrodes for an increase in diffusion limitation and thus more linear range, as well as for the minimization of the dependency of the sensor signal on the flow rate.…”

Section: Methods and Experimentalmentioning

confidence: 99%

“…Electrochemical sensors, in principle, are a perfect fit for such applications, since they allow for continuous acquisition of analyte concentrations dissolved in the liquid phase, while providing high spatial and temporal resolution and also allowing the precise detection of even small concentration changes, thanks to their high selectivity and sensitivity [ 17 , 18 , 19 , 20 , 21 , 22 ]. Despite these and other obvious advantages, electrochemical sensors are rarely used in the field of micro process technology.…”

Section: Introductionmentioning

confidence: 99%

“…Despite these and other obvious advantages, electrochemical sensors are rarely used in the field of micro process technology. Therefore, in prior works, we developed and used microsensors based on platinum electrochemistry for the amperometric in situ online monitoring of the synthesis educts and products inside the microreactor [ 21 , 23 ]. As shown in Figure 1 A, the previous sensor design was integrated at the bottom of the microchannel.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Methods and Experimentalmentioning

confidence: 99%

Section: Methods and Experimentalmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Microsensor Electrodes for 3D Inline Process Monitoring in Multiphase Microreactors

Urban

Sundaram

Kieninger

et al. 2020

Sensors

Self Cite

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“…This sensor is capable of performing under high analyte concentrations and high pressures. The authors also claim that the usage of this novel electrochemical sensor could minimise the risk of explosion due to high accuracy of detection [63].…”

Section: Ratio Of the Gaseous Mixturementioning

confidence: 96%

Recent Advances in the Direct Synthesis of Hydrogen Peroxide Using Chemical Catalysis—A Review

2018

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Hydrogen peroxide is an important chemical of increasing demand in today’s world. Currently, the anthraquinone autoxidation process dominates the industrial production of hydrogen peroxide. Herein, hydrogen and oxygen are reacted indirectly in the presence of quinones to yield hydrogen peroxide. Owing to the complexity and multi-step nature of the process, it is advantageous to replace the process with an easier and straightforward one. The direct synthesis of hydrogen peroxide from its constituent reagents is an effective and clean route to achieve this goal. Factors such as water formation due to thermodynamics, explosion risk, and the stability of the hydrogen peroxide produced hinder the applicability of this process at an industrial level. Currently, the catalysis for the direct synthesis reaction is palladium based and the research into finding an effective and active catalyst has been ongoing for more than a century now. Palladium in its pure form, or alloyed with certain metals, are some of the new generation of catalysts that are extensively researched. Additionally, to prevent the decomposition of hydrogen peroxide to water, the process is stabilized by adding certain promoters such as mineral acids and halides. A major part of today’s research in this field focusses on the reactor and the mode of operation required for synthesizing hydrogen peroxide. The emergence of microreactor technology has helped in setting up this synthesis in a continuous mode, which could possibly replace the anthraquinone process in the near future. This review will focus on the recent findings of the scientific community in terms of reaction engineering, catalyst and reactor design in the direct synthesis of hydrogen peroxide.

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Biomechanical study on implantable and interventional medical devices

et al. 2021

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Electrochemical multisensor system for monitoring hydrogen peroxide, hydrogen and oxygen in direct synthesis microreactors

Cited by 18 publications

References 62 publications

Microsensor Electrodes for 3D Inline Process Monitoring in Multiphase Microreactors

Microsensor Electrodes for 3D Inline Process Monitoring in Multiphase Microreactors

Recent Advances in the Direct Synthesis of Hydrogen Peroxide Using Chemical Catalysis—A Review

Biomechanical study on implantable and interventional medical devices

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