Gas separation membranes

Abstract

A gas separation membrane comprising the following layers: (i) a support layer; (ii) a buffer layer; (iii) a discriminating layer; (iv) optionally a fluorinated polymer layer; and (v) optionally a protective layer; wherein: (a) the buffer layer (ii) and the discriminating layer (iii) each independently comprise groups of Formula (1): M-(O—)x Formula (1) wherein: each M independently is a metal or metalloid atom; O is an oxygen atom; and each x independently has a value of at least 4; (b) the buffer layer (ii) comprises a surface comprising 4 to 10 atomic % of M of Formula (1) groups, wherein M is as hereinbefore defined; (c) the discriminating layer (iii) comprises a surface comprising more than 10 atomic % of M of Formula (1) groups, wherein M is as hereinbefore defined; and (d) layer (ii) is located between layers (i) and (iii).

Dependencies are inferred from the claim text.