Selective liquid-liquid extraction of oxidative desulfurization reaction products

Abstract

The present invention provides selective extraction of sulfoxides, or sulfoxides in combination with sulfones, from hydrocarbon mixtures containing these compounds. A significant advantage of the invention is that oxidation products resulting from oxidative desulfurization of hydrocarbon feedstocks are selectively extracted with minimum co-extraction of non-oxidized products such as valuable hydrocarbon fuel components.

We claim: 
     
         1 . An oxidative desulfurization process comprising:
 reactively sulfoxidating a hydrocarbon fraction containing organosulfur compounds to produce a hydrocarbon mixture containing product components, and by-product sulfoxides or a combination of sulfoxides and sulfones;   contacting the mixture with a selective solvent formulation comprising an aqueous solution having a concentration of about 2.5 weight % to about 70 weight % of a polar organic solvent, the polar organic solvent selected from the group consisting of acetone, methanol, acetonitrile, acetic acid, formic acid and combinations comprising at least two of the foregoing polar organic solvents,   wherein the concentration of the aqueous solution is selected to maximize extraction of target by-products and minimize co-extraction of product components including unoxidized organosulfur compounds and hydrocarbons including aromatic hydrocarbons,   wherein the extraction is conducted at temperatures of about 0° C. to about 40° C.; and   recovering a hydrocarbon product of reduced sulfur content.   
     
     
         2 . The process as in  claim 1 , wherein the concentration of the aqueous solution is about 2.5 weight % to about 20 weight % of acetone, and wherein the target compounds for extraction are non-bulky sulfoxide products. 
     
     
         3 . The process as in  claim 1 , wherein the concentration of the aqueous solution is about 20 weight % to about 50 weight % of acetone, and wherein the target compounds for extraction are bulky sulfoxide products. 
     
     
         4 . The process as in  claim 1 , wherein the concentration of the aqueous solution is about 10 weight % to about 30 weight % of methanol, and wherein the target compounds for extraction are non-bulky sulfoxide products. 
     
     
         5 . The process as in  claim 1 , wherein the concentration of the aqueous solution is about 5 weight % to about 30 weight % of acetonitrile, and wherein the target compounds for extraction are non-bulky sulfoxide products. 
     
     
         6 . The process as in  claim 1 , wherein the concentration of the aqueous solution is about 20 weight % to about 40 weight % of acetonitrile, and wherein the target compounds for extraction are bulky sulfoxide products. 
     
     
         7 . The process as in  claim 1 , wherein the concentration of the aqueous solution is about 2.5 weight % to about 20 weight % of acetic acid, and wherein the target compounds for extraction are non-bulky sulfoxide products. 
     
     
         8 . The process as in  claim 1 , wherein the concentration of the aqueous solution is about 20 weight % to about 40 weight % of acetic acid, and wherein the target compounds for extraction are bulky sulfoxide products. 
     
     
         9 . The process as in  claim 1 , wherein the concentration of the aqueous solution is about 5 weight % to about 20 weight % of formic acid, and wherein the target compounds for extraction are non-bulky sulfoxide products. 
     
     
         10 . The process as in  claim 1 , wherein the concentration of the aqueous solution is ab out 5 weight % to about 30 weight % of acetonitrile and about 5 weight % to about 30 weight % of formic acid. 
     
     
         11 . The process as in  claim 1 , wherein the concentration of the aqueous solution is about 5 weight % to about 30 weight % of acetic acid and about 5 weight % to about 30 weight % of acetone. 
     
     
         12 . The process as in  claim 1 , wherein the concentration of the aqueous solution is about 5 weight % to about 30 weight % of acetonitrile and about 5 weight % to about 30 weight % of acetone. 
     
     
         13 . The process as in  claim 1 , wherein an activity coefficient of the target by-product is less than about 16.5 and the activity coefficient of the aromatic hydrocarbons is greater than about 16.5. 
     
     
         14 . The process as in  claim 1 , wherein an activity coefficient of the target by-product is less than about 16.5 and the activity coefficient of unoxidized organosulfur compounds is greater than about 16.5. 
     
     
         15 . A method of determining an extraction solvent composition for extracting by-products from a hydrocarbon fraction containing by-products comprising:
 qualitatively analyzing the hydrocarbon fractions containing by-products to determine the type of by-products, and the type of aromatic hydrocarbons and/or the type of non-aromatic hydrocarbons;   selecting as a target by-products one or more sulfoxides or a combination of one or more sulfoxides and one or more sulfones;   determining the activity coefficient γ of a range of extraction solvent compositions for the target by-products and at least one type of aromatic or non-aromatic hydrocarbon, the extraction solvent compositions within the range of extraction solvent compositions comprising an aqueous solution having a concentration of about 2.5 weight % to about 70 weight % by weight polar organic solvent in water, the polar organic solvent selected from the group consisting of acetone, methanol, acetonitrile, acetic acid, formic acid and combinations comprising two or more of acetone, methanol, acetonitrile, acetic acid and formic acid;   selecting an extraction solvent composition having an activity coefficient of less than about 16.5 for the target by-products that maximizes extraction of the target by-products, and an activity coefficient greater than about 16.5 for the at least one type of aromatic or non-aromatic hydrocarbon that minimizes co-extraction of the at least one type of aromatic or non-aromatic hydrocarbon.   
     
     
         16 . The process as in  claim 1 , wherein the concentration of the aqueous solution is about 20 weight % to about 60 weight % of methanol, and wherein the target compounds for extraction are bulky sulfoxide products. 
     
     
         17 . The process as in  claim 1 , wherein the concentration of the aqueous solution is about 20 weight % to about 40 weight % of formic acid, and wherein the target compounds for extraction include 4,6-dimethyldibenzothiophene oxide. 
     
     
         18 . The process as in  claim 1 , wherein the concentration of the aqueous solution is about 20 weight % to about 30 weight % of acetone, and wherein the target compounds for extraction are non-bulky sulfoxides and sulfones. 
     
     
         19 . The process as in  claim 1 , wherein the concentration of the aqueous solution is about 30 weight % to about 50 weight % of methanol, and wherein the target compounds for extraction include dibutyl sulfoxides, dibutyl sulfone, thiophene sulfide, and thiophene sulfone. 
     
     
         20 . The process as in  claim 1 , wherein the concentration of the aqueous solution is about 10 weight % to about 20 weight % of acetonitrile, and wherein the target compounds for extraction include thiophene sulfide and thiophene sulfone. 
     
     
         21 . The process as in  claim 1 , wherein the concentration of the aqueous solution is about 10 weight % to about 30 weight % of acetic acid, and wherein the target compounds for extraction include thiophene sulfide and thiophene sulfone. 
     
     
         22 . The process as in  claim 1 , wherein the concentration of the aqueous solution is about 30 weight % to about 40 weight % of formic acid, and wherein the target compounds for extraction include thiophene sulfide and thiophene sulfone. 
     
     
         23 . The process as in  claim 1 , wherein reactively sulfoxidating a hydrocarbon fraction is effected by an oxidation process selected from the group consisting of photooxidation, photochemical oxidation, ozonation, ionic liquid oxidation, electro chemical oxidation, bio-desulfurization, oxidation by hydrogen peroxide, oxidation by organic peracid, oxidation by peroxomonophosphoric acid, oxidation by nitrogen oxides, oxidation by nitric acid, and a combination of any of the foregoing oxidation processes.