Alloy design of V-based hydrogen permeable membrane under given temperature and pressure condition

- A concept for alloy design of H2 permeable membrane has been applied for V-Fe system.
- In this concept, hydriding property must be controlled appropriately.
- In view of the thermodynamic parameters, hydriding property can be controlled.
- Correlation between membrane area and applicable hydrogen pressure is discussed.
- A concept for scale up of the membrane area is obtained.

For alloy design of hydrogen permeable membrane, it is important to control pressure-composition-isotherm (PCT curve) in an appropriate manner in order to obtain high hydrogen permeability with strong resistance to hydrogen embrittlement. Based on this concept, V-based alloy membranes are designed under some given pressure conditions at a temperature in view of the partial molar enthalpy change, ΔH¯0.2, and entropy change, ΔS¯0.2, of hydrogen for hydrogen dissolution. It is demonstrated that the PCT curve can be controlled very precisely in view of ΔH¯0.2 and ΔS¯0.2. Also, the required membrane area to obtain 300 Nm3 h−1 of hydrogen flow is estimated. It is found that, in view of the membrane area, it is favorable to apply at least 400 kPa of hydrogen pressure at feed side.