Pressure-dependent hydrogen permeability extended for metal membranes not obeying the square-root law.

Hydrogen permeability of metal membranes is generally defined by the square-root law, as the proportional coefficient of permeation flux to the square-root difference of the pressures on both sides of the membrane. However, deviation from the law has been widely reported for palladium, niobium, etc. Although n-th power instead of the square root has often been employed to determine permeability for these membranes, it has no theoretical base.

Thin and defect-free Pd-based composite membrane without any interlayer and substrate penetration by a combined organic and inorganic process.

A novel combined organic and inorganic process for preparing thin supported membrane was developed, using which a thin and defect-free Pd membrane with uniform thickness of 5 microm was directly coated onto porous alpha-Al2O3 hollow fiber without any interlayer and substrate penetration; at the same time, there existed a small interstice between membrane and substrate, which led to higher hydrogen permeance, infinite selectivity, and better membrane stability.