Hydrogen sulphide and mercaptans scavenging compositions

A composition for scavenging hydrogen sulphide and mercaptans in hydrocarbon streams, said composition comprising at least one H2S scavenger compound and at least one additive,

• the H2S scavenger compound being selected from oxazolidine compounds, triazine, and metal-based carboxylate, and
• the additive being a copolymer comprising m units of formula (II) and p units of formula (III), wherein:
• Wherein
• R3 and R5 are, independently to each other, a hydrogen atom or a methyl group,
• m is an integer ranging from 2 to 200,
• p is an integer ranging from 2 to 100,
• R4 represents independently to each other, a monovalent radical selected from linear, branched, cyclic, alkyl or alkenyl groups having from 1 to 36 carbon atoms and aryl groups having from 6 to 16 carbon atoms, said alkyl, alkenyl or aryl group may optionally be substituted by one or more heteroatoms, such as oxygen, sulfur, nitrogen atoms,
• R6 represents independently to each other, a divalent radical selected from linear, branched, cyclic, alkylene or alkenylene groups having from 1 to 36 carbon atoms and arylene groups having from 6 to 16 carbon atoms, said alkylene, alkenylene or arylene group may optionally be substituted by one or more heteroatoms, such as oxygen, sulfur, nitrogen atoms,
• R7, R8 and R9, are independently to each other, a monovalent radical selected from linear, branched, cyclic, alkyl or alkenyl groups having from 1 to 36 carbon atoms.