the sameUS5820659 *28 Mar 199713 Oct 1998L'air Liquide, Societe Anonyme Pour L'etude Et, L'exploitation Des Procedes Georges ClaudeMulticomponent or asymmetric gas separation membranesUS5855647 *15 May 19975 Ene 1999American Air Liquide, Inc.Process for recovering SF6 from a gasUS5858065 *16 Ene 199712 Ene 1999American Air LiquideEffluent gases, e.g. from the semiconductor manufacturing process, e