Patent ID: 7238214

Claim:
A method for producing a diesel fuel composition having enhanced lubricity, said method comprising combining a major amount of a diesel fuel as base fuel with up to 8 weight % of a nitrogen rich fraction said nitrogen rich fraction being separated and recovered from oils and fossil fuels selected from the group consisting of refinery process stream or fuel blend which refinery process stream or fuel blend distill within a diesel oil boiling range of 150-400° C. and such that the sulphur to nitrogen atom ratio in said nitrogen rich fraction is less than 4, said nitrogen rich fraction being separated and recovered from said refinery process stream or fuel blend by (a) using a stationary/liquid phase separation method in which the stationary phase is an absorbent, or (b) a liquid/liquid phase separation based on the preferential partition of the components of the appropriate fractions between mutually immiscible solvents, or (c) osmosis through a membrane.