Since inter- and intra-particle heterogeneities in catalyst particles are more the rule than the exception, it is advantageous to perform high-throughput screening for the activity of single catalyst particles. A multiphase system (gas/liquid/solid) is developed, where droplet-based microfluidics and optical detection are combined for the analysis of single catalyst particles by safely performing a hydrogenation study on in-house synthesized hollow Pd/SiO₂ catalyst microparticles, in a polydimethylsiloxane (PDMS) microreactor. A two-phase segmented flow system of particle-containing droplets is combined with a parallel gas-reactant channel separated from the flow channel by a 50 μm thick gas permeable PDMS wall. In this paper, the developed microreactor system is showcased by monitoring the Pd-catalyzed hydrogenation of methylene blue. A discoloration of blue to brown visualizes the hydrogenation activity happening in a high-throughput fashion on the single Pd/SiO₂ spherical catalyst microparticles, which are encapsulated in 50 nL-sized droplets. By measuring the reagent concentration at various spots along the length of the channel the reaction time can be determined, which is proportional to the residence time in the channel. The developed experimental platform opens new possibilities for single catalyst particle diagnostics in a multiphase environment.

中文翻译：

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微反应器中用于进行多相加氢反应的单催化剂颗粒诊断

由于催化剂颗粒中的颗粒间和颗粒内异质性比一般情况更普遍，因此对单个催化剂颗粒的活性进行高通量筛选是有利的。开发了一种多相系统（气/液/固），其中通过安全地对内部合成的中空Pd / SiO ₂进行氢化研究，将基于液滴的微流控和光学检测相结合以分析单个催化剂颗粒聚二甲基硅氧烷（PDMS）微反应器中的催化剂微粒。包含颗粒的液滴的两相分段流系统与平行的气体反应器通道组合，该通道与气体通道之间通过50μm厚的可渗透PDMS壁隔开。在本文中，通过监测钯催化的亚甲基蓝氢化反应展示了已开发的微反应器系统。蓝色到棕色的变色显示了在单个Pd / SiO ₂上以高通量方式发生的氢化活性球形催化剂微粒，包裹在50 nL大小的液滴中。通过测量沿通道长度的各个点处的试剂浓度，可以确定反应时间，该时间与通道中的停留时间成比例。开发的实验平台为多相环境中的单催化剂颗粒诊断提供了新的可能性。