Non-Thermal Plasma Desulfurization of Petroleum Products and Method Thereof

Abstract

This invention discloses methods and processes to separate sulfur hydrocarbons in petroleum refinery feedstocks via non-thermal corona-discharged air (known as cold plasma). The procedure comprises physical and chemical processes including single or multi-step oxidation of nonpolar sulfur hydrocarbons by ozone bubbling and optionally the simultaneous addition of an extremely small amount of hydrogen peroxide. This is followed by an aqueous liquid/non-aqueous liquid extraction of the oxidized compounds under conditions sufficient to extract sulfur compounds into the aqueous extractant. This process is followed by a regeneration unit for the recovery of liquid extractant material. Moreover, a cooling tower is employed to prevent exhausting the vapors of hydrocarbon feedstocks, as a form of volatile organic compounds, during the plasma bubbling process. The invention introduces a desulfurization technique that effectively separates sulfur hydrocarbons from petroleum feedstocks and fuels, offering a complementary solution to traditional hydrodesulfurization processes or serving as a standalone system.

What is claimed is: 
     
         1 . A process for separating sulfur compounds from hydrocarbon feedstock thereby obtaining a sulfur-depleted product, the process comprising:
 providing the hydrocarbon feedstock;   bubbling the hydrocarbon feedstock in a plasma oxidation reaction system with an ozone-rich stream, as a primary oxidizer, to obtain treated hydrocarbon, the treated hydrocarbon comprising oxidized sulfur compounds; and   separating the oxidized sulfur compounds from the treated hydrocarbon to obtain the sulfur-depleted product;   
       wherein the process is free of added metal-based catalysts or hydrogen. 
     
     
         2 . The process according to  claim 1 , wherein the hydrocarbon feedstock is NGC, naphtha, diesel, kerosene, fuel oil, SRD or combinations thereof. 
     
     
         3 . The process according to  claim 1 , wherein the sulfur compounds comprise aliphatic or refractory aromatic compounds such as mercaptans, thiophenes, benzo-thiophenes, and dibenzothiophenes. 
     
     
         4 . The process according to  claim 1 , further comprising:
 adding a secondary oxidizing compound during the bubbling step comprising at least one of hydrogen peroxide, sulfuric acid, potassium permanganate and nitric acid.   
     
     
         5 . The process according to  claim 1 , wherein the bubbling step is non-thermal. 
     
     
         6 . The process according to  claim 1 , wherein the ozone-rich stream is corona discharged. 
     
     
         7 . The process according to  claim 1 , wherein the separating step comprises liquid-liquid extraction. 
     
     
         8 . The process according to  claim 1 , wherein bubbles in contact with the hydrocarbon feedstock, in the bubbling step, are in the form of micro-bubbles having a size range from 10 to 100 micrometers. 
     
     
         9 . The process according to  claim 1 , wherein the process is carried out in continuous form or non-continuous form. 
     
     
         10 . The process according to  claim 1 , wherein the plasma oxidation reaction system comprises one or more plasma oxidation reactors. 
     
     
         11 . The process according to  claim 1 , wherein the bubbling in each of the one or more plasma oxidation reactors is carried out at a predetermined height of hydrocarbon feedstock, the predetermined height ranging from about 1.5 m to about 4.5 m. 
     
     
         12 . The process according to  claim 1 , further comprising:
 returning vapors of hydrocarbon components during the bubbling steps back to the plasma oxidation reactor.   
     
     
         13 . The process according to  claim 1 , wherein the separating step comprises contacting the oxidized sulfur compounds with a polar solvent, wherein the polar solvent comprises a caustic solution, methanol, dimethyl formamide or acetonitrile. 
     
     
         14 . The process according to  claim 1 , wherein the separating step is carried out at a duration from about 30 min to about 2 hours. 
     
     
         15 . The process according to  claim 1 , wherein a desulfurization efficiency of up to 90% is achieved. 
     
     
         16 . A system configured for separating sulfur compounds from a hydrocarbon feedstock, the system comprising:
 a reaction vessel for receiving the hydrocarbon feed stock, the reaction vessel comprising an inlet for the hydrocarbon feedstock, an outlet for treated hydrocarbon;   at least one nozzle at or proximate to the bottom of the reaction vessel configured to deliver an ozone-rich stream, in the form of bubbles, to the reaction vessel containing the hydrocarbon feedstock; and   an extraction unit for separating sulfur compounds from the treated hydrocarbon exiting the reaction vessel.   
     
     
         17 . The system according to  claim 16 , wherein the reaction vessel operates at a predetermined height of the hydrocarbon feedstock therein, the predetermined height ranging from about 1.5 m to about 4.5 m. 
     
     
         18 . The system according to  claim 16 , wherein the bubbles are micro-bubbles having a size range from about 10 micrometers to about 100 micrometers. 
     
     
         19 . The system according to  claim 16 , wherein the system operates upstream or downstream of a traditional desulfurization plant.