Oil desulfurization method and system

Abstract

An oil desulfurization method may be used to desulfurize various oils, such as used motor oil, crude oil, diesel, high sulfur fuel oil, mid sulfur fuel oil, off-spec fuel oil, and off-spec diesel, to produce a finished product of lower sulfur oil and a high sulfur fuel oil or sulfur containing oil product. Preferably, the method may include the steps of: mixing an oxidizing material with sulfur containing oil to produce a first mixture; subjecting the first mixture to at least one of heat and pressure to oxidize the sulfur in the first mixture; mixing at least one solvent with the first mixture to produce a second mixture; and separating the second mixture to produce a low sulfur oil product and a third mixture, the third mixture having a high sulfur oxidized oil and the at least one solvent.

What is claimed is: 
     
         1 . An oil desulfurization method, the method comprising the steps of:
 mixing an oxidizing material with sulfur containing oil to produce a first mixture;   subjecting the first mixture to at least one of heat and pressure to oxidize the sulfur in the first mixture;   mixing at least one solvent with the first mixture to produce a second mixture; and   separating the second mixture to produce a low sulfur oil product and a third mixture, the third mixture having a high sulfur oxidized oil and the at least one solvent.   
     
     
         2 . The method of  claim 1 , wherein the oxidizing material mixed with sulfur containing oil to produce a first mixture includes at least one of: ambient air, ozone, compressed air, oxygen, nitrogen oxygen mixtures, hydrogen peroxide, peracetic acid, and acetic acid. 
     
     
         3 . The method of  claim 1 , wherein the first mixture is subjected to oxidation of sulfur in the presence of a catalyst. 
     
     
         4 . The method of  claim 3 , wherein catalyst includes at least one of: Zn-ZSM, Mo-ZSM, Fe-ZSM, and Co-ZSM. 
     
     
         5 . The method of  claim 1 , further comprising the step of passing the low sulfur oil product through a polar zeolite to extract additional oil holding sulfur. 
     
     
         6 . The method of  claim 5 , wherein the low sulfur oil is passed through the polar zeolite in the presence of oxygen. 
     
     
         7 . The method of  claim 5 , wherein the low sulfur oil is passed through the polar zeolite in the absence of oxygen. 
     
     
         8 . The method of  claim 1 , further comprising the step of separating the at least one solvent from the third mixture to produce a high sulfur oxidized oil product. 
     
     
         9 . The method of  claim 8 , wherein the at least one solvent is separated from the third mixture using distillation. 
     
     
         10 . The method of  claim 9 , wherein the at least one solvent is separated from the third mixture is reused as the at least one solvent used perform the step of mixing at least one solvent with the first mixture to produce a second mixture. 
     
     
         11 . The method of  claim 1 , wherein the at least one solvent comprises a polar solvent. 
     
     
         12 . The method of  claim 1 , wherein the at least one solvent comprises at least one polar solvent selected from: tamisolve, N-ethyl pyrrolidone (NEP), diethyl carbonate, ethylene carbonate dimethyl carbonate, cyrene, Dimethylformamide (DMF), N-Methyl-2-pyrrolidone (NMP), and propylene carbonate. 
     
     
         13 . The method of  claim 1 , wherein the at least one solvent comprises 
     
     
         14 . The method of  claim 1 , wherein the at least one solvent is introduced to the first mixture at a rate between 10% to 100% of oil volume. 
     
     
         15 . The method of  claim 1 , wherein the at least one solvent is introduced to the first mixture at a temperature of between 32 and 90 degrees Fahrenheit. 
     
     
         16 . The method of  claim 1 , wherein the second mixture is separated via a centrifuge. 
     
     
         17 . The method of  claim 1 , wherein the first mixture is subjected to pressure above ambient pressure and between 5 to 30 pounds per square in gauge (psig) back pressure. 
     
     
         18 . The method of  claim 1 , wherein the at least one solvent is mixed with the first mixture to produce a second mixture via a static mixer.