Tailored ceramic catalyst support structures for heterogeneous catalytic reactions

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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.