Tailored ceramic catalyst support structures for heterogeneous catalytic reactions

该项目的目的是开发用于微反应器的定制催化剂载体。这种载体的内部和外部结构以及因此的传质和压降性能可以通过所应用的制备技术来调节。由相转化纺丝制备的多孔纤维和中空纤维组成的结构非常适合于这一发展目标。该纺丝技术的应用允许针对某些化学反应定制催化剂载体的若干结构参数。纤维的内部孔隙率及其可达性可以通过影响纺丝工艺的参数来调节。内扩散电阻的调整将通过有效扩散系数的测量来证明。除了影响内部传质性能外，所应用的纺丝工艺允许在三维结构的制备步骤内调节纤维直径、纤维排列和空隙率。这些结构特性对于外部传质和压降是至关重要的。对于纤维基催化剂载体结构的这些特性，将在本项目中开发相关性。基于这些相关性，传质和压降之间的权衡可以针对特定应用进行调整。对于最终的>设计指南<，特别是低雷诺数区域至关重要，因为理论模型预测在此低雷诺数下质量传递会恶化。由于该模型的实验验证目前还不可能令人满意，因此将在本项目中进行模型和实验之间的比较。应用于催化测量的微分再循环反应器允许在低雷诺数下估计传质性质，排除由于反应器的无梯度操作引起的轴向扩散效应的影响。在本项目范围内制备的广泛表征的纤维基催化剂支撑结构可应用于微反应器中的各种应用。

The aim of the project is the development of tailored catalyst supports for application in microreactors. The internal as well as the external structure of this supports and thus the mass transfer and pressure drop properties can be adjusted by the applied preparation technique. Structures consisting of porous fibers and hollow fibers prepared by phase inversion spinning are highly suitable for this development goal. Application of this spinning technique allows tailoring of several structural parameters of the catalyst support to certain chemical reactions. The inner porosity of the fibers and their accessibility can be adjusted by influencing the parameters of the spinning process. The adjustment of internal diffusion resistances will be proven by measurements of the effective diffusion coefficients. Besides influencing the internal mass transfer properties the applied spinning process allows the adjustment of fiber diameter, fiber arrangement and void fraction within the preparation step of the three-dimensional structure. These structural properties are crucial for external mass transfer and pressure drop. For these properties of the fiber based catalyst support structures correlations will be developed within this project. Based on these correlations the trade-off between mass transfer and pressure drop can be tailored to a certain application. For the resulting >design guideline< especially the area of low Reynolds numbers is of crucial importance, because theoretical models predict a deterioration of mass transfer at this low Reynolds numbers. Because experimental validation of this models were not satisfactorily possible up to now, the comparison between model and experiment will be carried out within this project. The differential recycle reactor applied for catalytic measurements allows the estimation of mass transfer properties at low Reynolds numbers excluding the influence of axial diffusion effects due to the gradient free operation of the reactor. The extensively characterized fiber based catalyst support structures prepared within the scope of this project can be applied to various applications in microreactors.