Oxidative desulfurization of fuel oil

Abstract

A method for purifying a sulfur-containing fuel oil comprising (a) contacting in a first reaction mixture the sulfur-containing fuel oil with a water-soluble organic acid and oxygen at a temperature in a range of from about 100° C. to about 250° C., and at a pressure in a range of from about 15 pounds per square inch to about 2500 pounds per square inch to provide a first oxidized mixture, (b) adding water to provide a biphasic mixture comprising a water-rich phase and a fuel oil-rich phase, and (c) separating the water-rich phase from the fuel oil-rich phase to provide a purified fuel oil. In one embodiment, the method may further include an oxidation catalyst. In one embodiment, the method may further include a carbonaceous promoter. In one embodiment, the sulfur-containing fuel oil may be deasphalted before contacting with the water-soluble organic acid.

1 . A method for purifying a sulfur-containing fuel oil, said method comprising:
 (a) contacting in a first reaction mixture the sulfur-containing fuel oil with a water-soluble organic acid and oxygen at a temperature in a range of from about 100° C. to about 250° C., and at a pressure in a range of from about 15 pounds per square inch to about 2500 pounds per square inch to provide a first oxidized mixture;   (b) adding water to provide a biphasic mixture comprising a water-rich phase and a fuel oil-rich phase; and   (c) separating the water-rich phase from the fuel oil-rich phase to provide a purified fuel oil.   
   
   
       2 . The method of  claim 1 , wherein the water-soluble organic acid is selected from the group consisting of acetic acid, formic acid, propionic acid, butyric acid, and mixtures of two or more of the foregoing acids. 
   
   
       3 . The method of  claim 1 , wherein the water-soluble organic acid is acetic acid. 
   
   
       4 . The method of  claim 1 , wherein the first reaction mixture further comprises a transition metal oxidation catalyst. 
   
   
       5 . The method of  claim 4 , wherein the transition metal oxidation catalyst comprises oxides or salts of metals selected from the group consisting of vanadium, manganese, molybdenum, tungsten, cobalt, nickel, copper, and a combination of at least two of the foregoing metals. 
   
   
       6 . The method of  claim 5 , wherein the transition metal oxidation catalyst comprises an oxide or salt of copper. 
   
   
       7 . The method of  claim 4 , wherein the transition metal oxidation catalyst is supported on a metal oxide. 
   
   
       8 . The method of  claim 7 , wherein the metal oxide support is selected from the group consisting of silica, alumina, titania, ceria and a combination of at least two of the foregoing metal oxides. 
   
   
       9 . The method of  claim 1 , wherein the first reaction mixture further comprises a carbonaceous promoter. 
   
   
       10 . The method of  claim 9 , wherein the carbonaceous promoter comprises an activated carbon with high surface area. 
   
   
       11 . The method of  claim 1 , wherein the sulfur-containing fuel oil comprises less than 5 weight percent sulfur. 
   
   
       12 . The method of  claim 1 , wherein the sulfur-containing fuel oil comprises less than 3 weight percent sulfur. 
   
   
       13 . The method of  claim 1 , wherein the pressure is in a range of from about 1000 pounds per square inch to about 2250 pounds per square inch 
   
   
       14 . The method of  claim 1 , wherein the oxygen is provided as a mixture with an inert gas. 
   
   
       15 . The method of  claim 14 , wherein the oxygen is provided as air. 
   
   
       16 . The method of  claim 1 , wherein the water-rich phase comprises at least 50 percent of the water-soluble organic acid. 
   
   
       17 . The method of  claim 1 , further comprising a step of recovering the water-soluble organic acid from the water-rich phase. 
   
   
       18 . The method of  claim 17 , wherein the water-soluble organic acid is recovered from the water-rich phase by distillation. 
   
   
       19 . The method of  claim 1 , wherein the sulfur-containing fuel oil comprises dibenzothiophene, benzothiophene, alkyl substituted dibenzothiophenes, and alkyl substituted benzothiophenes. 
   
   
       20 . The method of  claim 1 , wherein the sulfur-containing fuel oil is deasphalted prior to contacting the sulfur-containing fuel oil with the water-soluble organic acid. 
   
   
       21 . A method for purifying a sulfur-containing fuel oil, said method comprising:
 (a) contacting in a first reaction mixture a sulfur-containing fuel oil comprising dibenzothiophene, benzothiophene, alkyl substituted dibenzothiophenes, and alkyl substituted benzothiophenes with acetic acid and oxygen at a temperature in a range of from about 130° C. to about 200° C., and at a pressure in a range of from about 1800 pounds per square inch to about 2200 pounds per square inch to provide a first oxidized mixture comprising sulfoxides and sulfones of dibenzothiophene, benzothiophene, alkyl substituted dibenzothiophenes, and alkyl substituted benzothiophenes;   (b) adding water to provide a biphasic mixture comprising a water-rich phase comprising at least 50 percent of the acetic acid and a fuel oil-rich phase; and   (c) separating the water-rich phase from the fuel oil-rich phase to provide a purified fuel oil.   
   
   
       22 . The method of  claim 21 , wherein the sulfur-containing fuel oil comprises less than 5 weight percent sulfur. 
   
   
       23 . The method of  claim 21 , further comprising a step of recovering the water-soluble organic acid from the water-rich phase. 
   
   
       24 . The method of  claim 21 , wherein the sulfur-containing fuel oil is deasphalted prior to contacting the sulfur-containing fuel oil with the water-soluble organic acid. 
   
   
       25 . A method for purifying a sulfur-containing fuel oil, said method comprising:
 (a) adding a diluent to the sulfur-containing fuel oil to provide a heterogeneous mixture comprising an asphaltene-rich phase and a first fuel-oil rich phase;   (b) separating the asphaltene-rich phase from the first fuel-oil rich phase;   (c) contacting the first fuel-oil rich phase with a water-soluble organic acid and oxygen at a temperature in a range of from about 100° C. to about 250° C., and at a pressure in a range of from about 15 pounds per square inch to about 2500 pounds per square inch to provide a first oxidized mixture;   (d) adding water to provide a biphasic mixture comprising a water-rich phase and a second fuel oil-rich phase; and   (e) separating the water-rich phase from the second fuel oil-rich phase to provide a purified fuel oil.