A hollow fiber membrane probe for the measurement of the hydrogen concentration in a liquid

Holstvoogd, R.D.; Hof, J.A. van 't; Swaaij, W.P.M. van

doi:10.1016/0009-2509(91)85054-2

Cited by 2 publications

(2 citation statements)

References 2 publications

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“…Several sensors and techniques for the measurement of dissolved hydrogen or oxygen have been proposed and studied in the past. − Although these worked well for specific applications, they cannot generally be used for chemical multiphase processes that may involve temperature ranges from 300 to 500 K, reactor pressures from 0.1 to 10 MPa, and corrosive chemical environments. This major drawback was eliminated by the Fugatron, which can be employed more generally in the fields of process control and chemical reaction engineering.…”

Section: Introductionmentioning

confidence: 99%

In Situ Measurement of Steady-State Hydrogen Concentrations during a Hydrogenation Reaction in a Gas-Inducing Stirred Slurry Reactor

Meyberg¹,

Roessler²

2005

Ind. Eng. Chem. Res.

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A new instrument, the Fugatron, is presented that was developed to make in situ measurements of dissolved hydrogen concentrations in laboratory reactors. The principle of measurement is based on a probe with a tip that consists of a small porous metal substrate coated with a dense layer of fluoropolymer. The probe is exposed to the liquid phase and is internally purged by a constant flow of carrier gas. Driven by the hydrogen concentration gradient between the external and internal side of the composite layer, the hydrogen molecules permeate into the carrier gas stream. The concentration of the permeate in the carrier gas stream is measured by a gas analyzer. The analyzer signal is proportional to the partial pressure of dissolved gas. The steady-state concentration of dissolved hydrogen in the liquid is calculated from the analyzer signal by using solubility data. Calibration methods are described for immersion probes used for in situ measurements in reactors which are operated in batch or continuous mode as well as for flow-through probes used for liquid stream analysis. The sensitivity of the instrument and the reliability of the measurements were tested in different solutions as a function of temperature and pressure. The hydrogenation of an alkyne with a suspended palladium catalyst was chosen as a model reaction for in situ measurements. The hydrogenation experiments were carried out in a 0.5-L stirred-tank reactor with a turbine stirrer in a semibatch mode. Initial hydrogen uptake rates and dissolved hydrogen concentrations during this model reaction were measured as a function of the amount of catalyst in the liquid. The solubility of hydrogen in the pure liquid was determined by a gas absorption measurement at reaction conditions. From these measurements, the volumetric liquid-side mass transfer coefficient k L a at the gas−liquid interface was calculated as a function of catalyst loading. In addition, the k L a value was also determined in the absence of solid particles by the dynamic pressure drop method. Discrepancies that may result from calculating steady-state dissolved hydrogen concentrations using k L a values obtained from measurements conducted either in pure liquids or in liquids that contain suspended catalyst particles are discussed and illustrated by these measurements. The new method allows direct measurement of the concentrations of dissolved gases during a reaction, which can be a decisive factor for the rate as well as for the selectivity of a process. Estimations of the gas concentrations via reaction rate data and cumbersome determinations of k L a values are, therefore, no longer necessary.

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Section: Introductionmentioning

confidence: 99%

In Situ Measurement of Steady-State Hydrogen Concentrations during a Hydrogenation Reaction in a Gas-Inducing Stirred Slurry Reactor

Meyberg¹,

Roessler²

2005

Ind. Eng. Chem. Res.

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show abstract

“…A useful Hg detector utilizing a membrane was developed by Holstvoogd et al (1991) for somewhat different applications. The detector could measure the Hg dissolved in silicone oils up to a temperature of 423 K by allowing it to diffuse continuously inside a poly-(ethers sulfone) hollow fiber membrane where it is conveyed by an inert gas to a thermal conductivity detector.…”

Section: Introductionmentioning

confidence: 99%

Measuring Conversions in Dehydrogenation Reactions with the Aid of a Pd-Ag Membrane

Ali¹,

Baiker²

1995

Ind. Eng. Chem. Res.

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A hollow fiber membrane probe for the measurement of the hydrogen concentration in a liquid

Cited by 2 publications

References 2 publications

In Situ Measurement of Steady-State Hydrogen Concentrations during a Hydrogenation Reaction in a Gas-Inducing Stirred Slurry Reactor

In Situ Measurement of Steady-State Hydrogen Concentrations during a Hydrogenation Reaction in a Gas-Inducing Stirred Slurry Reactor

Measuring Conversions in Dehydrogenation Reactions with the Aid of a Pd-Ag Membrane

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