Relationship between hydrogen permeability and the physical-chemical characteristics of metal alloy membranes

Abstract

Due to the vast compositional range of advanced hydrogen-selective alloys, quantitative and well-targeted development are extremely challenging. This paper examines a wide range of bond properties related to high-H2 permeability metal membranes. An investigation of the relationships between hydrogen (H2) permeability and physical-chemical characteristics, namely, atomic radius difference (delta), mixed entropy (Delta S), electronega-tivity difference (Delta chi), and valence electron concentration (VEC), was proposed using a data set of 170H2 permeation experiments at 673 K collected from about 70 scientific literature references regarding Pd-, Ni-, Nb-, Ti-, V-, and Zr-based binary, ternary, or more complex alloy membranes. The following conclusions can be drawn from the selected experimental data collected in the literature: It seems that for the metal alloy membranes, the H2 permeation properties have a close correlation to bond parameters. On the whole, the H2 permeability increased as the VEC decreased, regardless of alloy membranes and other characteristics. If light VEC metals are considered to consist of any metal having a relatively low valence electron concentration, light VEC alloys are seen to be the greatest options for achieving high H2 permeability. Our physical-chemical criterion, which is based on the bond properties of metal alloy membranes, can be utilized to both create new H2-selective alloy membranes and improve the efficiency of currently studied membranes.