(WO9805414-A1)      A composite membrane consists of a microporous base membrane (A) and a separating layer (B) with a thickness of not more than 3 microns consisting of a block copolyether-ester (I).    USE -    For the separation of polar gases, especially water vapour, hydrogen sulphide, carbon dioxide, ammonia and/or ethylene oxide, from gas mixtures, particularly for the simultaneous removal of water vapour and H2S from gas mixtures, especially natural gas (claimed).    ADVANTAGE -    A composite membrane with good mechanical and chemical stability and high separation factors for polar gases, especially water vapour and H2S. The membrane also shows a high ammonia/nitrogen selectivity and is unaffected by condensed water (unlike cellulose acetate membranes).    (DE19631841-C2)      A composite membrane consists of a microporous base membrane (A) and a separating layer (B) with a thickness of not more than 3 microns consisting of a block copolyether-ester (I).    USE -    For the separation of polar gases, especially water vapour, hydrogen sulphide, carbon dioxide, ammonia and/or ethylene oxide, from gas mixtures, particularly for the simultaneous removal of water vapour and H2S from gas mixtures, especially natural gas (claimed).    ADVANTAGE -    A composite membrane with good mechanical and chemical stability and high separation factors for polar gases, especially water vapour and H2S. The membrane also shows a high ammonia/nitrogen selectivity and is unaffected by condensed water (unlike cellulose acetate membranes).    (EP946271-A1)      A composite membrane consists of a microporous base membrane (A) and a separating layer (B) with a thickness of not more than 3 microns consisting of a block copolyether-ester (I).    USE -    For the separation of polar gases, especially water vapour, hydrogen sulphide, carbon dioxide, ammonia and/or ethylene oxide, from gas mixtures, particularly for the simultaneous removal of water vapour and H2S from gas mixtures, especially natural gas (claimed).    ADVANTAGE -    A composite membrane with good mechanical and chemical stability and high separation factors for polar gases, especially water vapour and H2S. The membrane also shows a high ammonia/nitrogen selectivity and is unaffected by condensed water (unlike cellulose acetate membranes).