Project Details
Projekt
The role of interfaces in ceria-based multi-phase membranes for membrane reactors
Subject Area
Synthesis and Properties of Functional Materials
Term
from 2017 to 2023
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 387282673
The application of catalyst-coated O2-permeable membrane reactors is an energy efficient alternative to the commercially applied methods of synthesis in the area of heterogeneous catalysis. During such treatments, the oxygen which is necessary for conversion is taken from air. O2- ions are transported straight to the catalyst through a gastight thin ceramic layer. This combines the two steps of air separation and chemical conversion in one process.As most of these conversions take place at temperatures between 200 and 500 °C, membranes with a specific permeation rate of roughly 1 mlN cm-2 min-1 in this temperature range are necessary to ensure a significant conversion rate. The permeation through a ceramic oxygen permeation membrane takes place by solid state diffusion and mainly depends on the ambipolar conductivity, the thickness of the membrane and the oxygen partial pressure gradient across the membrane.Ceramic composites with one mainly oxide ion conductive and one electron conductive constituent are promising candidates for this kind of application as these materials combine a high oxygen flux with high mechanical and chemical stability under reaction conditions. However, research efforts so far have been focused on the temperature regime above 700 °C. To reach a good permeation rate also in the lower temperature range, the main effort, apart from basic adaption of the composition, will be the optimization of the interfaces between the single constituents. The reason is that a variety of reactions occur at the interfaces, which have a fundamental impact on the oxygen transport through the membrane.In course of the present project the consortium plans to systematically investigate the chemical and physical characteristics of the different interfaces or rather of transport processes taking place at the interfaces of an acceptor doped CeO2-based composite material with a spinel phase as electron conductive constituent, where FeCo2O4 will be the initial material. A more precise comprehension of the processes at grain boundaries and triple phase boundaries is the key for the planned purposeful optimization of the composite material for catalytic applications, e.g. by micro structuration or adaption of the chemical composition of the different phases. The chosen composites are planned to serve as examples for a series of CeO2-based multiphase composites. The fundamental insights from these investigations will be used to reach technologically relevant permeation rates at intermediate temperatures and thus to open a broader field of application to the working concept of a membrane reactor.
DFG Programme
Research Grants
