Electrical and electrochemical observation of direct synthesis of hydrogen peroxide in suspension flow micro reactors

该项目旨在深入了解多相多相催化化学反应的新型膜微反应器系统中发生的局部反应和传输过程的细节。这是通过使用集成在系统中的新型小型化传感器以及空间和时间分辨数值模拟来实现的。选择了钯基负载贵金属催化剂上由氢和氧直接合成过氧化氢的应用实例。该反应是目前催化领域的热门话题，也非常适合在微反应系统中进行。对于这个应用，在之前的项目中已经开发了一种调整氢氧浓度比以降低膜微反应器中流动方向的策略，现在需要将其付诸实践和评估，并结合基于催化剂涂层薄壁金属3d打印流体导向结构的改进反应器设计。在上一个项目中，已经开发出了实时测量空间和时间分辨浓度的电化学传感器，并成功地将其集成到压力高达100巴的反应器中。所述微反应器系统还包括一膜，用于将两种气态反应物沿相邻的蜿蜒状微通道系统直接注入反应介质中，使其无气泡投加。这种进行反应的方式为微反应器系统的安全运行提供了潜力，同时具有高选择性和高生产率。这是因为氢与氧的浓度比可以调整到催化反应的最佳值，即使是局部，也可以通过膜将两种反应物分开交替连续给药。这应通过实验证明，也可通过模拟定量再现。这也需要进一步改进传感器的可检测浓度范围和适用的反应介质。从一个角度来看，所产生的知识将用于开发一种新的强化技术，以便在当地高效和经济地生产过氧化氢，作为化学应用的绿色氧化剂。

The aim of this project is to gain deeper understanding of the details of the local reaction and transport processes taking place inside a novel membrane microreactor system for multiphase heterogeneously catalysed chemical reactions. This is achieved by use of novel miniaturised sensors integrated in the system combined with space and time-resolved numerical simulations. The direct synthesis of hydrogen peroxide from hydrogen and oxygen on palladium-based supported noble metal catalysts has been selected as an application case. This reaction is currently a topic of high interest in catalysis, and it is also well suited for being performed in microreaction systems. For this application, a strategy for adjusting the hydrogen to oxygen concentration ratio in order to decrease in the direction of flow in the membrane microreactor has ben developed in the previous project, which shall now be put in practice and evaluated together with an improved reactor design relying on catalyst-coated thin-walled metallic 3D-printed fluid guiding structures. For space and time-resolved measurement of the concentrations in real time electrochemical sensors have already been developed and successfully integrated into the reactor for pressures up to 100 bars in the previous project. The micro reactor system also includes a membrane for bubble-free dosage of both gaseous reactants directly into the reaction medium flowing along an adjacent meander-like micro channel system. This way of conducting the reaction offers the potential for safe operation of the microreactor system with, at the same time, high selectivity and productivity. This is because the concentration ratio of hydrogen versus oxygen can be adjusted to an optimal value for the catalysed reaction even locally by separate alternating continuous dosing of the two reactants via the membrane. This shall be proven experimentally and also be reproduced quantitatively by simulation. This will also require further improvements of the sensors regarding the detectable concentration range and the applicable reaction media. As a perspective, the knowledge generated shall be used for development of a new intensified technology for efficient and cost-effective local production of hydrogen peroxide as a green oxidant for chemical applications.