Process for upgrading diesel oils

A process for upgrading diesel oil comprising the steps of:

• (1) reacting the diesel oil with a nitrogenous treating agent;
• (2) contacting the diesel oil from step (1) above with
• (a) a primary solvent selected from the group consisting of organic solvents having a dipole moment of about 1.3 or greater and containing at least one of the following functional groups:
• ##STR3## and mixtures thereof or a water mixture of the primary solvent comprising about 50% by weight or less water;
• and
• (b) a cosolvent different from the primary solvent selected from the group consisting of an alcohol having 1 to 4 carbon atoms, an aldehyde having 1 to 2 carbon atoms, a ketone having 3 carbon atoms, a carboxylic acid having 1 or 2 carbon atoms, and mixtures thereof, or a water mixture of the cosolvent comprising about 50% by weight or less water;
• wherein the primary solvent and the cosolvent are each immiscible with the diesel oil or are in combination immiscible with the diesel oil, and
• (3) separating the diesel oil from step (2) above from the primary solvent and from the cosolvent to recover upgraded diesel fuel with improved cetane number.

A process for upgrading diesel oil comprising the steps of:

• (1) reacting the diesel oil with a nitrogenous treating agent;
• (2) contacting the diesel oil from step (1) above with
• (a) a primary solvent selected from the group consisting of furfural, butyrolactone, dimethyl formamide, dimethyl acetamide, methyl carbitol, tetrahydrofurfuryl alcohol, aniline, dimethyl sulfoxide, sulfolane, ethylene chlorohydrin, acetic anhydride, phenol, nitromethane, N-methylpyrrolidone, sulfolene, methanol, acetonitrile, ethyl cyanoacetate, acetic acid and mixtures thereof, or a water mixture of the primary solvent comprising about 50% by weight or less water, and
• (b) a cosolvent different from the primary solvent selected from the group consisting of an alcohol having 1 to 4 carbon atoms, an aldehyde having 1 or 2 carbon atoms, a ketone having 3 carbon atoms, a carboxylic acid having 1 or 2 carbon atoms, and mixtures thereof, or a water mixture of the cosolvent comprising about 50% by weight or less water;
• wherein the primary solvent and the cosolvent are each immiscible with the diesel oil or are in combination immisible with the diesel oil, and
• (3) separating the diesel oil from step (2) above from the primary solvent and from the cosolvent to recover upgraded diesel fuel with improved cetane number.