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

这个项目的目的是更深入地了解多相多相催化化学反应的新型膜微反应器系统内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微型传感器与空间和时间分辨率的数值模拟相结合来实现的。以钯为载体的贵金属催化剂上氢气和氧气直接合成过氧化氢反应为应用实例。该反应是目前催化领域的研究热点，也非常适合在微反应体系中进行。对于这一应用，在上一个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，现在将与依赖于催化剂涂层薄壁金属3D打印流体引导结构的改进的反应器设计一起进行实践和评估。在前一个项目中，已经开发了用于实时测量浓度的空间和时间分辨率的电化学传感器，并成功地将其集成到反应堆中，压力可达100巴。该微反应器系统还包括膜，用于无气泡地将两种气态反应物直接加入沿相邻的曲折状微通道系统流动的反应介质中。这种进行反应的方法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生产率。这是因为氢和氧的浓度比可以通过膜单独交替连续投加两种反应物来调节到催化反应的最佳值，即使是局部的。这一点应通过实验加以证明，并通过模拟进行定量再现。这也将要求传感器在可检测的浓度范围和适用的反应介质方面进一步改进。作为一种观点，所产生的知识应用于开发一种新的强化技术，以高效率和成本效益的方式在当地生产过氧化氢，作为一种用于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.