Patent ID: 8766022

Claim:
A method for synergistically increasing the cetane number of a fuel composition, the method comprising: providing an initial fuel composition exhibiting an initial cetane number, the initial fuel composition comprising 0.5% v/v. to 60% v/v. of one or more non Fischer Tropsch derived middle distillate fuel components and at least 40% v/v. Fischer-Tropsch derived fuel component; and adding to the fuel composition a concentration c of from 0.1% v/v. to 0.3% v/v. of an ignition improver to produce a fuel composition exhibiting a target cetane number that is 5% or more higher than the initial cetane number; wherein the concentration c is at least 50% lower than a theoretical concentration c′ required to achieve the target cetane number, the target cetane number is above a theoretically possible cetane number, and the target cetane number exhibits a cetane boost that is 70% or more higher than a theoretical cetane boost calculated based on the effects of the components of the fuel composition, individually; wherein the ignition improver is selected from the group consisting of organic peracids and organic peresters of the general formula R 4 —C(O)—O—O—R 5 , where R 4 and R 5 are each independently selected from the group consisting of hydrogen and hydrocarbyl groups having from 1 to 10 carbon atoms selected from the group consisting of alkyl groups, cycloalkyl groups, alkenyl groups, and aromatic groups.