Mixing-assisted oxidative desulfurization of diesel fuel using quaternary ammonium salt and portable unit thereof

Abstract

The desulfurization of fossil fuels is provided by the combination of fossil fuels with an aqueous mixture of ozone or hydrogen peroxide and a Tetraoctylphosphonium salt phase transfer catalyst, and the mixture is then subjected to reactive mixing to form oxidize sulfur compounds in the fuel. The polar oxidized sulfones species are removed via another mixing step. The desulfurization device can be in the form of a portable device which provides for continuous mixing-assisted desulfurization for the removal of sulfur containing compounds from fossil fuels such as diesel fuel.

1 . A method for removing sulfides from a liquid fossil fuel, comprising:
 (a) combining a liquid fossil fuel with an oxidizer solution, a metal catalyst, and a phase transfer catalyst to form a multiphase reaction medium; and   (b) reactive mixing the multiphase reaction medium for a time sufficient to cause oxidation of sulfides in the fossil fuel to sulfones and to produce a plurality of bubble formations comprising a substantial number of bubbles of less than 1 mm in diameter in a desulfurization reactor.   
     
     
         2 . The method for removing sulfides in accordance with  claim 1 , further comprising:
 separating the oil phase from the aqueous phase using a first cyclone.   
     
     
         3 . The method for removing sulfides in accordance with  claim 2 , further comprising:
 mixing and separating of the oil phase from a polar solvent phase via a polar solution extractor.   
     
     
         4 . The method for removing sulfides in accordance with  claim 3 , further comprising producing a plurality of bubble formations comprising a substantial number of bubbles of less than 1 mm in diameter in the polar solution extractor. 
     
     
         5 . The method for removing sulfides in accordance with  claim 2 , further comprising:
 recycling the aqueous solvent solution including the phase transfer catalyst, the oxidizer solution, and the metal catalyst.   
     
     
         6 . The method for removing sulfides in accordance with  claim 3 , further comprising:
 separating the oil phase from the polar solvent phase using a second cyclone.   
     
     
         7 . The method for removing sulfides in accordance with  claim 6 , further comprising:
 separating and collecting the sulfones to yield an organic phase that is substantially sulfone-free.   
     
     
         8 . The method in accordance with  claim 1 , wherein the phase transfer catalyst is a quaternary ammonium salt, the quaternary ammonium salt having four substituents, the substituents are from the group consisting of an alkyl group having a chain length of from 1 to 20 carbon atoms, an aryl group, or an aralkyl group, and at least one of the substituents is an alkyl group of 8 or more carbon atoms in length. 
     
     
         9 . The method in accordance with  claim 8 , wherein the phase transfer catalyst is Tetraoctylphosphonium salt. 
     
     
         10 . The method for removing sulfides in accordance with  claim 1 , wherein the oxidizer solution comprising of hydrogen peroxide, hydroperoxide, or ozone. 
     
     
         11 . The method in accordance with  claim 1 , wherein the mixing ratio of liquid fossil fuel and the oxidizer solution is about 1:1 to about 1:3. 
     
     
         12 . The method in accordance with  claim 1 , wherein the metal catalyst is selected from the group consisting of iron (II), iron (III), copper (I), copper (II), chromium (III), and chromium (VI) compounds, and molybdates, tungstates, and vanadates with the liquid fossil fuel and the oxidizer solution to form the multiphase reaction medium. 
     
     
         13 . The method in accordance with  claim 12 , wherein the metal catalyst is a phosphotungstic acid. 
     
     
         14 . The method in accordance with  claim 1 , wherein the liquid fossil fuel is a member selected from the group consisting of crude oil, shale oil, diesel fuel, gasoline, kerosene, liquefied petroleum gas, and petroleum residual-based fuel oils. 
     
     
         15 . The method in accordance with  claim 1 , wherein the liquid fossil fuel is diesel fuel or diesel fuel blend. 
     
     
         16 . A method for removing sulfides from a liquid fossil fuel, comprising:
 (a) combining a liquid fossil fuel with an oxidizer solution, a metal catalyst, and a phase transfer catalyst to form a multiphase reaction medium; wherein the oxidizer solution comprising ozone, and   (b) reactive mixing the multiphase reaction medium for a time sufficient to cause oxidation of sulfides in the fossil fuel to sulfones.   
     
     
         17 . A method for removing sulfides from a liquid fossil fuel, comprising:
 (a) combining a liquid fossil fuel with an oxidizer solution, a metal catalyst, and a phase transfer catalyst to form a multiphase reaction medium; wherein the phase transfer catalyst comprising Tetraoctylphosphonium salt, and   (b) reactive mixing the multiphase reaction medium for a time sufficient to cause oxidation of sulfides in the fossil fuel to sulfones.   
     
     
         18 . A portable continuous desulfurization device, comprising:
 a plurality of mixing tanks;   a mixer connected to each mixing tank for agitation and mixing to produce a plurality of bubble formations comprising of bubble sizes less than substantially 1 mm in diameter;   a plurality of cyclones coupled to the mixing tanks in series, respectively; and   an evaporative tower, wherein the evaporative tower is coupled to one cyclone, and one cyclone yields an organic phase that is substantially sulfone-free.   
     
     
         19 . The continuous desulfurization device according to  claim 18 , wherein the mixer is connected to the mixing tank with a recirculation loop. 
     
     
         20 . The continuous desulfurization device according to  claim 18 , wherein a liquid fossil fuel is combined with an oxidizer solution, a metal catalyst, and a phase transfer catalyst to form a multiphase reaction medium in a first mixing tank, and the multiphase reaction medium is reactive mixed for a time sufficient to cause oxidation of sulfides in the fossil fuel to sulfones in the first mixing tank, a first cyclone is used for separating the oil phase from the aqueous phase, a second mixing tank is a polar solution extractor, and the polar solution extractor is provided for mixing and separating of the oil phase from a polar solvent phase and producing a plurality of bubble formations comprising a substantial number of bubbles of less than 0.1 mm in diameter, and a second cyclone is provided for separating the oil phase from the polar solvent phase 
     
     
         21 . The continuous desulfurization device according to  claim 18 , wherein the phase transfer catalyst is Tetraoctylphosphonium salt, the oxidizer solution comprising of hydrogen peroxide, hydroperoxide, or ozone, the mixing ratio of liquid fossil fuel and the oxidizer solution is about 1:1 to about 1:3, and the metal catalyst is a phosphotungstic acid. 
     
     
         22 . The continuous desulfurization device according to  claim 19 , wherein the recirculation loop providing recycling of the aqueous solvent solution, and the aqueous solvent solution including the phase transfer catalyst, the oxidizer solution, and the metal catalyst.