CFD-MRI Reactions – A Combined Measurement-Simulation Approach for Reactive Flow Characterization

催化过程非常重要：许多日常生活产品和技术都需要使用催化剂。它们被用于原材料的定价、污染物或废物的转化，或用于生产化学品和最终产品。在化工技术领域，高达90%的过程使用催化剂，其中80%是多相催化。由于其在增值链中的重要性，催化工艺的每一次改进都将产生多方面的经济影响。了解化学反应器中的浓度、速度和温度分布对于详细了解反应是必不可少的。从这样的分布中，可以推断出质量和热传递、(侧面)产品的形成和工艺限制，使它们在反应堆设计中发挥重要作用。传统的测量分布的技术往往是侵入性的，或者充其量只有一维空间分辨率。CFD计算需要精确的边界条件和几何知识。磁共振成像可以测量空间分辨的温度、浓度、局部速度和许多其他量。然而，这项技术存在分辨率低、噪声高和测量时间长的问题，尤其是在气相应用中。CFD-MRI方法是由Pi Krause小组发展起来的，它对MRI数据进行数值后处理，以降低噪声，提高分辨率。在相对较低的作用力下，这已经在几个简单几何形状的非反应性流动中显示出来。CFD-MRI反应项目的目的是开发CFD-MRI方法和MRI测量，使其适用于复杂几何形状的反应流。这将有助于解开反应机理。我们将使用三维核磁共振测量固定床流动反应器中化学反应的流动和物质浓度。仅使用这些数据，我们不仅识别了基本几何结构和反应动力学，而且还获得了无噪声和高得多分辨率的速度和物种浓度的图像。这给出了高空间分辨率的流动和化学反应的详细表征。首先，我们对开孔泡沫中的液体和气体流动进行了磁共振测量。我们使用CFD-MRI来寻找潜在的几何图形，以及在显著降低噪声的情况下获得原始场的高分辨率图像。其次，我们使用光谱核磁共振技术来测量泡沫中非均相催化的液相反应过程中的浓度图。我们将使用CFD-MRI来获取动力学参数，并将提高分辨率并降低原始测量的噪声。在项目期间，我们不仅将产生方法洞察力，还将发布所有软件开放源码，以允许所有研究人员访问。该项目的结果使我们更接近于完全表征多相催化的气相反应。

Catalytic processes are of tremendous importance: many everyday life products and technologies require the use of a catalyst. They are used for the valorization of raw materials, conversion of pollutants or waste, or for the production of chemicals and final goods. Up to 90% of all processes in the chemical technology sector make use of a catalyst with 80% of them being heterogeneous catalysis. Due to its importance in the value-added chain, every improvement to catalytic processes will have a manifold economic effect. Knowledge of concentration, velocity, and temperature distribution in a chemical reactor are essential for a detailed understanding of the reaction. From such distribution, it is possible to deduce mass and heat transfer, (side) product formation, and process limitations, giving them a major role in reactor design. Conventional techniques to measure distributions are often invasive or only have one-dimensional spatial resolution at best. CFD calculations require exact knowledge of the boundary conditions and geometry. MRI can measure spatially resolved temperature, concentration, local velocities, and many other quantities. The technique, however, suffers from low resolution, high noise, and long measurement times, which is especially true for gas phase applications. The CFD-MRI method, developed in the group of PI Krause, applies numerical post-processing on MRI data to reduce noise and increase the resolution. At comparably low effort, this was already shown for several non-reactive flows in simple geometries. Aim of the CFD-MRI Reactions project is to develop the CFD-MRI method together with the MRI measurements to make it applicable for reactive flows in complex geometries. This will help to unravel reaction mechanisms. We will use three-dimensional MRI measurements of flow and species concentration from a chemical reaction in a fixed-bed flow reactor. Using this data alone, we identifynot only the underlying geometry as well as the reaction kinetics but also obtain images of the velocity and species concentration without noise and at a significantly higher resolution. This gives a detailed characterization of flow and chemical reactions with high spatial resolution. Firstly, we perform MRI measurements of both liquid and gas flow in an open-cell foam. We use CFD-MRI to find the underlying geometry as well as a high resolution image of the original fields at significantly reduced noise. Secondly, we use spectroscopic MRI to measure concentration maps during a heterogeneously catalyzed liquid-phase reaction in the foam. We will use CFD-MRI to obtain kinetic parameters and will increase resolution and reduce noise of the original measurements. During the project we will not only generate methodological insight but will also publish all software open source to allow access to all researchers. The results from this project bring us one step closer to a full characteracterization of heterogeneously catalyzed gas phase reactions.