General Criteria for Membrane Design

In this section, we provide a rational analysis of perovskite materials for membrane design in view of high-temperature CO2 capture applications. Our purpose is to establish structure-property relationships for identifying the main formulations offering potentials for separation imder different scenarios. To address a proper technical integration of perovskite membranes into CO2 capture processes, the following key elements have to be addressed  

The permeation performance of dense membranes is often characterized in terms of a transmembrane flux, ji, at a given temperature and pressure gradient. Alternatively, a specific flux, /, can be defined as a normalized membrane flux based on the thicloiess and logarithm of the partial pressure gradient as a reminiscence of the Wagner equation. The specific flux can be related to the membrane permeability as follows  

To properly compare the results reported by different authors and to compare the performance of perovskites with other materials such as silicas, zeolites, and MOFs, the following definitions for gas permeance, permeability, and separation fector will be hereinafter used  

Gas permeability (F, ) gas permeance multiplied by the top-layer effective thickness  

Separation factor (SF,y) feed-to-permeate ratio between the molar compositions of species i and /  

---