Two-step heterocyclic nitrogen extraction from petroleum oils

A process for the removal of basic heterocyclic nitrogen compounds from petroleum oils which comprises:

• (a) contacting said petroleum oils containing basic heterocyclic nitrogen compounds with an aqueous solution of an acidic solvent at extraction conditions in a first contacting zone,
• (b) separating the product of step (a) into a raffinate product stream comprising hydrocarbons having a lean content of basic heterocyclic nitrogen compounds and residual acid levels, and a first extract phase comprising hydrocarbons, water and acid having a substantial content of basic heterocyclic nitrogen compounds,
• (c) contacting said first extract phase with a hydrocarbon solvent that is substantially immiscible with said first extract phase wherein said hydrocarbon solvent and extraction conditions are selected such that the ratio of nitrogen-free oil distribution coefficient to basic nitrogen distribution coefficient is greater than about 10 in a second contacting zone, and
• (d) separating the product oil step (c) into a hydrocarbon recovery stream comprising the immiscible hydrocarbon solvent and oil-derived hydrocarbons having a lean content of basic heterocyclic nitrogen compounds and a second extract phase comprising acid, water, a high content of basic heterocyclic compounds and a decreased amount of nitrogen-free hydrocarbons.

A process for the removal of basic heterocyclic nitrogen compounds from petroleum oils which comprises:

• (a) contacting said petroleum oils containing basic heterocyclic nitrogen compounds with an aqueous solution of an acidic solvent selected from the group consisting of aliphatic organic carboxylic acids, halogen-substituted carboxylic acids and mixtures thereof, at extraction conditions in a first contacting zone,
• (b) separating the product of step (a) into a raffinate product stream comprising hydrocarbons having a lean content of basic heterocyclic nitrogen compounds and residual acid levels, and a first extract phase comprising hydrocarbons, water and acid having a substantial content of basic heterocyclic nitrogen compounds,
• (c) contacting said first extract phase with a non-polar hydrocarbon solvent that is substantially immiscible with said first extract phase at extraction conditions in a second contacting zone, and
• (d) separating the product of step (c) into a hydrocarbon recovery stream comprising the immiscible hydrocarbon solvent and oil-derived hydrocarbons having a lean content of basic heterocyclic nitrogen compounds and a second extract phase comprising acid, water, a high content of basic heterocyclic compounds and a decreased amount of nitrogen-free hydrocarbons.

A process for the removal of basic heterocyclic nitrogen compounds from petroleum oils which comprises:

• (a) contacting said petroleum oils containing basic heterocyclic nitrogen compounds with an aqueous solution of an acidic solvent having an acid concentration in the range of from about 25% by weight to about 99% by weight, per total weight of solvent at extraction conditions in a first contacting zone,
• (b) separating the product of step (a) into a raffinate product stream comprising hydrocarbons having a lean content of basic heterocyclic nitrogen compounds and residual acid levels, and a first extract phase comprising hydrocarbons, water and acid having a substantial content of basic heterocyclic nitrogen compounds,
• (c) contacting said first extract phase with a non-polar hydrocarbon solvent that is substantially immiscible with said first extract phase at extraction conditions in a second contacting zone, and
• (d) separating the product of step (c) into a hydrocarbon recovery stream comprising the immiscible hydrocarbon solvent and oil-derived hydrocarbons having a lean content of basic heterocyclic nitrogen compounds and a second extract phase comprising acid, water, a high content of basic heterocyclic compounds and a decreased amount of nitrogen-free hydrocarbons.