The present invention relates to a composition for scavenging hydrogen sulphide and/or mercaptans in hydrocarbon streams, the composition comprising an oxazolidine compound and a synergistic additive.

The present invention relates to a composition for scavenging hydrogen sulphide and/or mercaptans in hydrocarbon streams, the composition comprising an oxazolidine compound and a synergistic additive.

The present invention relates to a composition for scavenging hydrogen sulphide and/or mercaptans in hydrocarbon streams, the composition comprising an oxazolidine compound and a synergistic additive.

The subject matter of the present invention is a fuel composition which comprises —at least 85% by weight of one or more fractions of hydrocarbons having a distillation range within the range extending from 100 to 400° C. and having a paraffin content greater than or equal to 90% by weight; —at least a first additive consisting of a particular quaternary ammonium salt; and —at least a second additive consisting of a phenolic antioxidant. The subject matter of the invention is also the use of a composition of additives comprising said first and second additives, for improving at least one property of a paraffin-rich fuel composition.

A method for preparing a substituted fuel additive d is provided. The method comprises carrying out the following reaction: (a) (b) (d), The fuel additive d may be used as an octane-boosting additive in a fuel for a spark-ignition internal combustion engine. ##STR00001##

A method for preparing a substituted fuel additive d is provided. The method comprises carrying out the following reaction: (a) (b) (d), The fuel additive d may be used as an octane-boosting additive in a fuel for a spark-ignition internal combustion engine. ##STR00001##

A method for preparing a refinery fuel composition having a target octane number, comprises: (i) blending fuel components in proportions which are designed to give a refinery fuel composition with an octane number which is greater than the target octane number by a margin of less than 1; and (ii) testing the octane number of the refinery fuel composition and, if the octane number falls below the target octane number, blending the refinery fuel composition with a non-metallic octane-boosting additive. A further method comprises: (a) passing a first refinery fuel composition comprising a non-metallic octane-boosting additive to a fuel handing system, and discharging the first refinery fuel composition from the fuel handing system; and (b) passing a second refinery fuel composition to the fuel handing system.

A method for preparing a refinery fuel composition having a target octane number, comprises: (i) blending fuel components in proportions which are designed to give a refinery fuel composition with an octane number which is greater than the target octane number by a margin of less than 1; and (ii) testing the octane number of the refinery fuel composition and, if the octane number falls below the target octane number, blending the refinery fuel composition with a non-metallic octane-boosting additive. A further method comprises: (a) passing a first refinery fuel composition comprising a non-metallic octane-boosting additive to a fuel handing system, and discharging the first refinery fuel composition from the fuel handing system; and (b) passing a second refinery fuel composition to the fuel handing system.

A method for reducing the tendency of a hydrocarbon fluid to oxidise comprises combining an additive having a chemical structure comprising a 6-membered aromatic ring sharing two adjacent aromatic carbon atoms with a 6- or 7-membered saturated heterocyclic ring, the 6- or 7-membered saturated heterocyclic ring comprising a nitrogen atom directly bonded to one of the shared carbon atoms to form a secondary amine and an atom selected from oxygen or nitrogen directly bonded to the other shared carbon atom, the remaining atoms in the 6- or 7-membered heterocyclic ring being carbon with the hydrocarbon fluid. The additive may also be used for protecting a system in which a hydrocarbon fluid is used from the effects of oxidation.

A method for reducing the tendency of a hydrocarbon fluid to oxidise comprises combining an additive having a chemical structure comprising a 6-membered aromatic ring sharing two adjacent aromatic carbon atoms with a 6- or 7-membered saturated heterocyclic ring, the 6- or 7-membered saturated heterocyclic ring comprising a nitrogen atom directly bonded to one of the shared carbon atoms to form a secondary amine and an atom selected from oxygen or nitrogen directly bonded to the other shared carbon atom, the remaining atoms in the 6- or 7-membered heterocyclic ring being carbon with the hydrocarbon fluid. The additive may also be used for protecting a system in which a hydrocarbon fluid is used from the effects of oxidation.