Oxygen transport membranes (OTM) can be used in the fields of oxy-combustion, the separation of pure oxygen or in membrane reactors for the synthesis of chemical energy carriers or commodity chemicals. The advantages of membranes are their higher energy efficiency compared to conventional processes as well as their modularity. Advanced membranes are designed in an asymmetric way, i.e. a thin dense membrane layer on a porous support providing sufficient mechanical stability. This structure, however, leads to a very complex combination of several transport mechanisms.
For a differentiated consideration of 12 individual material, microstructural, and operational parameters a 1D transport model is applied to asymmetric OTM. The model includes surface exchange, ionic and electronic transport as well as binary diffusion, Knudsen diffusion and viscous flux inside the support pores enabling the definition of a support limitation factor. A systematic sensitivity analysis revealed that for materials with very high ambipolar conductivity the transport is limited by the porous support in particular the pore tortuosity while for materials with low ambipolar conductivity the transport is limited by the dense membrane. The model identifies the most performance-sensitive parameters of the entire set of 12. Therefore, it is well suited guiding experimentalists in the targeted development of high performance gas separation membranes for any kind of application.