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.

中文翻译：

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液-液界面面积对以加氢甲酰化为例的双相催化的影响

双相催化通过将均相催化剂固定在与产物不混溶的附加液相中，能够有效地回收均相催化剂。引入的液-液界面区域意味着传质限制，这在理解这些催化系统中起着重要作用，许多速率提高策略都围绕着优化所述区域展开。在这篇文章中，通过应用一种利用基于图像的原位图像的方法，阐明了液-液界面面积和催化活性之间的关系。测量瞬态液滴尺寸分布。当以工业上高度相关的长链烯烃 1-辛烯的水性双相加氢甲酰化作为模型反应时，发现产物壬醛和配体的添加使界面面积增加了高达 5 倍。发现转化率取决于搅拌速度。通过催化剂浓度的变化，表明催化剂物质在界面处的积累是不可能的。使用数学模型，强调水-有机界面面积对催化活性的影响不是文献中先前假设的线性。相反，提出了界面组成的变化，这会导致催化活性对所述区域的依赖性发生变化。因此，