Systems for producing fuel compositions with predetermined desirable properties are disclosed. Feedback control can be employed to meter precise amounts of fuel composition components while monitoring fuel composition properties to obtain fuel compositions having specifically defined properties.

A method for reducing the propensity of a fuel to form an emulsion 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 fuel. Thus, the additive may be used as a demulsifier in a fuel.

Disclosed are cloud point depressants and methods of making and using them. The disclosed cloud point depressants comprise copolymers of a maleic moiety polymerized with alpha olefins and then contacted with an aliphatic tertiary amine to provide a cloud depressant reaction product. When the disclosed reactions products are added to middle distillate fuels or blends of middle distillate fuels with biodiesel, the cloud point depressants inhibit the precipitation of waxes and/or biowaxes in the fuels and the fuels exhibit reduced precipitation, gelling, and/or crystallization when subjected to low or cold temperatures.

An organomodified silicone material is shown and described herein. The organomodified silicone provides a material that can be used as an additive in a fuel oil, e.g., diesel fuel. The organomodified silicone acts as both a defoamer and a dehazer in a fuel oil.

New compositions and certain corresponding components are useful for reducing crystallization of paraffin crystals in fuels.

A method for reducing the propensity of a fuel to form an emulsion 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 fuel. Thus, the additive may be used as a demulsifier in a fuel.

Use of a hydrocarbyl-substituted dicarboxylic acid for improving or boosting the separation of water from fuel oils and gasoline fuels which comprise additives with detergent action. A Fuel additive concentrate comprising the said hydrocarbyl-substituted dicarboxylic acid, certain additives with detergent action and optionally other customary additives and solvents or diluents.

Use of a hydrocarbyl-substituted dicarboxylic acid for improving or boosting the separation of water from fuel oils and gasoline fuels which comprise additives with detergent action. A Fuel additive concentrate comprising the said hydrocarbyl-substituted dicarboxylic acid, certain additives with detergent action and optionally other customary additives and solvents or diluents.

Mixtures of certain olefin-carboxylic acid copolymers (A) with at least one additive with detergent action, preferably at least one quaternary nitrogen compound (B), and optionally further fuel additives, are useful for improving or boosting the separation of water from fuel oils and gasoline fuels.

A diesel fuel composition comprising a first additive (i) comprising a quaternary ammonium salt and a second additive (ii) comprising a Mannich reaction product; wherein the quaternary ammonium salt additive (i) is formed by the reaction a quaternising agent which is not an ester and a compound formed by the reaction of a hydrocarbyl-substituted acylating agent and an amine of formula (B1) or (B2): wherein R.sup.2 and R.sup.3 are the same or different alkyl, alkenyl or aryl groups having from 1 to 22 carbon atoms; X is a bond or alkylene group having from 1 to 20 carbon atoms; n is from 0 to 20; m is from 1 to 5; and R.sup.4 is hydrogen or a C.sub.1 to C.sub.22 alkyl group; and wherein the Mannich reaction product additive (ii) is the product of a Mannich reaction between: (d) an aldehyde; (e) an amine; and (f) a substituted phenol; wherein the phenol is substituted with at least one branched hydrocarbyl group having a molecular weight of between 200 and 3000.