Tropfenbewegung und Stofftransport in technischen Flüssig/flüssig‐Systemen. Teil 2: Auswirkung von Grenzflächeneffekten und Verunreinigungen

Schulz, Joschka M.; Petzold, M.; Böhm, Lutz; Kraume, Matthias

doi:10.1002/cite.202000247

Cited by 2 publications

(2 citation statements)

References 57 publications

(128 reference statements)

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“…The effect of TPPTS addition on a LL is explained by a change in the ionic strength of the aqueous phase by the addition of a salt. A change in the ionic strength of water is known to influence the electric double layer at the droplet interface. , This disturbs the electrochemical potential, resulting in a repulsion, and thereby inhibits the coalescence of droplets. In comparison, addition of 150 mol m aq –3 of sodium sulfate instead of 100 mol m aq –3 of TPPTS led to an average a LL value of 1128 m –1 as opposed to 1036 m –1 a difference of 8%.…”

Section: Resultsmentioning

confidence: 99%

“…Product inhibition as a cause for this phenomenon cannot be excluded. Another explanation is found in the results of single-drop experiments that give valuable insights into the effect of impurities and additives on interfacial phenomena. , Paul et al showed that an increase in surfactant concentration at the aqueous–organic interface leads to a decrease in mass transfer rate and an increase in solubility in the aqueous phase . In addition, when they used a nonionic surfactant in a water–1-octanol system, Paul et al found that even a partial interfacial coverage of a droplet can change its behavior to that of a particle with a rigid interface, reducing inner circulations of the droplet and thereby decreasing the mass transfer rate .…”

Section: Resultsmentioning

confidence: 99%

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Effect of Liquid–Liquid Interfacial Area on Biphasic Catalysis Exemplified by Hydroformylation

et al. 2022

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Biphasic catalysis enables the effective recycling of homogeneous catalysts by their immobilization in an additional liquid phase immiscible with the products. The introduced liquid− liquid interfacial area implies mass transfer limitations that play an important role in understanding these catalytic systems, with many rate enhancement strategies revolving around optimizing said area. In this contribution, the relationship between liquid−liquid interfacial area and catalytic activity is elucidated by applying a methodology that utilizes an image-based in situ measurement of the transient droplet size distribution. When the industrially highly relevant aqueous biphasic hydroformylation of the long-chain olefin 1-octene is taken as the model reaction, it is found that the product nonanal and the addition of the ligand increases the interfacial area by a factor of up to 5. The rate of conversion is found to depend on the stirring speed. By variation of the catalyst concentration, it is shown that an accumulation of the catalyst species at the interface is unlikely. Using a mathematical model, it is highlighted that the effect of the aqueous−organic interfacial area on the catalytic activity is not linear as was previously assumed in the literature. Instead, a change in the interfacial composition is proposed that causes a shift in the dependence of catalytic activity on said area. Thus, the dynamic physical properties of a lean gas−liquid−liquid system were linked to the catalytic performance of the system.

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Section: Resultsmentioning

confidence: 99%