Methods and systems for treating petroleum feedstock containing organic acids and sulfur

Abstract

Methods and systems of treating petroleum feedstock contaminated with naphthenic acids and sulfur are disclosed. The methods and systems include heating the petroleum feedstock to decompose the naphthenic acids, pressurizing to minimize the portion in the vapor phase, sweeping water vapor and carbon dioxide into a headspace with a non-oxidizing gas, removing water vapor and carbon dioxide from the headspace, reacting the sulfur with an alkali metal and a radical capping gas to convert the sulfur into alkali sulfides, and removing the alkali sulfides. Also disclosed is reacting the naphthenic acid with water and an oxide or hydroxide of an alkaline earth element to convert the naphthenic acid into naphthenates, removing water, ketonizing, removing oxides or carbonates, reacting the sulfur with an alkali metal and a radical capping gas to convert the sulfur into alkali sulfides, and removing the alkali sulfides.

1 . A method for treating petroleum feedstock comprising:
 providing a petroleum feedstock comprising naphthenic acids and sulfur;   heating the petroleum feedstock to decompose the naphthenic acids;   pressurizing the petroleum feedstock to minimize a portion of the petroleum feedstock in a vapor phase;   sweeping water vapor and carbon dioxide from the petroleum feedstock into a headspace with a non-oxidizing gas;   removing water vapor and carbon dioxide from the headspace to promote naphthenic acid decomposition;   reacting the sulfur with an alkali metal and a radical capping gas to convert the sulfur into alkali sulfides; and   removing the alkali sulfide.   
     
     
         2 . The method of  claim 1 , wherein the petroleum feedstock is heated in a range of about 200° C. to about 425° C. 
     
     
         3 . The method of  claim 1 , wherein the petroleum feedstock is heated in a range of about 300° C. to about 400° C. 
     
     
         4 . The method of  claim 1 , wherein the non-oxidizing gas comprises hydrogen, light hydrocarbon gas, pyrolysis gas, or combinations thereof. 
     
     
         5 . The method of  claim 1 , wherein the alkali metal comprises lithium, sodium, potassium, or combinations thereof. 
     
     
         6 . The method of  claim 1 , wherein the radical capping gas comprises one or more of the following: methane, ethane, propane, butane, pentane, hexane, heptane, octane, ethene, propene, butane, pentene, hexene, heptene, octene, and isomers of the foregoing, natural gas, shale gas, liquid petroleum gas, ammonia, primary, secondary, and tertiary ammines, thiols, mercaptans, and hydrogen sulfide. 
     
     
         7 . The method of  claim 1 , further comprising regenerating the alkali metal from the alkali metal sulfide. 
     
     
         8 . The method of  claim 7 , wherein regenerating the alkali metal from the solids comprises an electrolytic process using an alkali metal ion conductive ceramic membrane. 
     
     
         9 . A method for treating petroleum feedstock comprising:
 providing a petroleum feedstock comprising naphthenic acids and sulfur;   reacting the naphthenic acid an aqueous solution or slurry containing an oxide or hydroxide of an alkaline earth element while heating to convert the naphthenic acid into alkaline earth naphthenates, thereby generating an alkaline earth naphthenate mixture;   removing water from the alkaline earth naphthenate mixture to generate a dewatered mixture;   reacting the sulfur in the dewatered mixture with an alkali metal and a radical capping gas to convert the sulfur into alkali sulfides; and   removing the alkali sulfides.   
     
     
         10 . The method of  claim 9 , wherein the alkaline earth mixture is heated in a range of about 80° C. to about 95° C. 
     
     
         11 . The method of  claim 9 , wherein the dewatered mixture is heated in a range of about 300° C. to about 400° C. 
     
     
         12 . The method of  claim 9 , wherein the alkali metal comprises sodium and the alkaline earth element comprises one or more of calcium, strontium, or barium. 
     
     
         13 . The method of  claim 9 , further comprising regenerating the alkali metal from the alkali metal sulfide. 
     
     
         14 . The method of  claim 7 , wherein regenerating the alkali metal from the solids comprises an electrolytic process using an alkali metal ion conductive ceramic membrane. 
     
     
         15 . A method for treating petroleum feedstock comprising:
 providing a petroleum feedstock comprising naphthenic acids and sulfur;   reacting the naphthenic acid with an aqueous solution or slurry containing an oxide or hydroxide of an alkaline earth element while heating to convert the naphthenic acid into an alkaline earth naphthenate, thereby generating an alkaline earth naphthenate mixture;   removing water from the alkaline earth naphthenate mixture to generate a dewatered mixture;   heating the dewatered mixture to convert alkaline earth naphthenates into ketones and alkaline earth oxides or alkaline earth carbonates, thereby generating a ketone mixture;   removing alkaline earth oxides or alkaline earth carbonates from the ketone mixture;   reacting the sulfur in the ketone mixture with an alkali metal and a radical capping gas to convert the sulfur into alkali sulfides; and   removing the alkali sulfide.   
     
     
         16 . The method of  claim 15 , wherein the dewatered mixture is heated in a range of about 166° C. to about 312° C. 
     
     
         17 . The method of  claim 15 , wherein heating the dewatered mixture to convert alkaline earth naphthenates into ketones and alkaline earth oxides or alkaline earth carbonates and reacting the sulfur with an alkali metal and a radical capping gas to convert the sulfur into an alkali sulfide is carried out at the same time in a single reaction vessel. 
     
     
         18 . The method of  claim 17 , wherein the alkali metal comprises sodium and the alkaline earth element comprises one or more of calcium, strontium, or barium. 
     
     
         19 . The method of  claim 15 , further comprising regenerating the alkaline earth carbonates with heat to form alkaline earth oxides. 
     
     
         20 . The method of  claim 15 , wherein removing the alkaline earth oxides or alkaline earth carbonates and the alkali sulfide comprises filtration, centrifugation, hydrocyclonic separation, or combinations thereof.