Cerium dioxide nanoparticle-containing fuel additive

Abstract

A fuel additive composition includes: a) a reverse-micellar composition having an aqueous disperse phase that includes cerium dioxide nanoparticles in a continuous phase that includes a hydrocarbon liquid, a surfactant, and optionally a co-surfactant and b) a reverse micellar composition having an aqueous disperse phase that includes a cetane improver effective for improving engine power during fuel combustion. A method of making a cerium-containing fuel additive includes the step of: a) providing a mixture of a nonpolar solvent, a surfactant, and a co-surfactant; and b) combining the mixture with an aqueous suspension of stabilized cerium dioxide nanoparticles.

What is claimed: 
     
         1 . A reverse-micellar composition for use as a fuel additive, said composition comprising:
 a) a disperse phase comprising an aqueous composition that includes a free radical initiator providing cetane improvement; and   b) a continuous phase comprising a hydrocarbon liquid and a surfactant.   
     
     
         2 . The reverse-micellar composition according to  claim 1 , wherein said free radical initiator is selected from the group consisting of stabilized hydrogen peroxide, t-butyl hydroperoxide, and combinations thereof. 
     
     
         3 . The reverse-micellar composition according to  claim 1 , comprising micelles having a mean hydrodynamic diameter of about 1 nm to about 50 nm. 
     
     
         4 . The reverse-micellar composition according to  claim 3 , comprising micelles having a mean hydrodynamic diameter of about 2 nm to about 10 nm. 
     
     
         5 . The reverse-micellar composition according to  claim 1 , further comprising cerium-containing nanoparticles. 
     
     
         6 . The reverse-micellar composition according to  claim 5 , wherein the cerium-containing nanoparticles are cerium dioxide nanoparticles having a mean hydrodynamic diameter of about 1 nm to about 15 nm. 
     
     
         7 . The reverse-micellar composition according to  claim 6 , wherein the cerium dioxide nanoparticles have a mean hydrodynamic diameter of up to about 10 nm. 
     
     
         8 . the reverse-micellar composition according to  claim 7 , wherein the cerium dioxide nanoparticles have a mean hydrodynamic diameter of up to about 8 nm. 
     
     
         9 . The reverse-micellar composition according to  claim 8 , wherein the cerium dioxide nanoparticles have a mean hydrodynamic diameter of about 6 nm. 
     
     
         10 . The reverse-micellar composition according to  claim 5 , wherein said cerium-containing nanoparticles are disposed in micelles separate from the micelles containing said free radical innitiator. 
     
     
         11 . A fuel additive composition comprising:
 a) a reverse micellar composition comprising an aqueous disperse phase that includes stabilized, non-agglomerated cerium dioxide nanoparticles in a continuous phase comprising a hydrocarbon liquid, a surfactant, and optionally a co-surfactant; and   b) a reverse micellar composition comprising an aqueous disperse phase that includes a cetane improver effective for improving engine power during fuel combustion.   
     
     
         12 . The fuel additive composition according to  claim 11 , wherein the cerium dioxide nanoparticles and cetane improver are included within the same reverse micellar composition. 
     
     
         13 . The fuel additive composition according to  claim 11 , wherein said cerium dioxide nanoparticles have a mean hydrodynamic diameter of about 1 nm to about 50 nm. 
     
     
         14 . The fuel additive composition according to  claim 13 , wherein said cerium dioxide nanoparticles have a mean diameter of about 2 nm to about 10 nm. 
     
     
         15 . A fuel additive composition comprising:
 a) a reverse-micellar composition comprising an aqueous disperse phase that includes nanoparticles that are formed in situ and comprise a cerium (IV) oxidic compound; and   b) a continuous phase that includes a hydrocarbon liquid and a surfactant/stabilizer mixture;   
       wherein said surfactant/stabilizer mixture is effective to restrain particle size, prevent particle agglomeration, and enhance the yield of said nanoparticles. 
     
     
         16 . The fuel additive composition according to  claim 15 , wherein said nanoparticles comprise cerium dioxide (CeO 2 ) and have a mean diameter of about 1 nm to about 15 nm. 
     
     
         17 . The fuel additive composition according to  claim 15 , wherein said surfactant/stabilizer mixture is selected from among; a mixture of at least one non-ionic surfactant and at least one ionic surfactant, or a combination of a single-charged ionic surfactant and a multiple-charged ionic surfactant, both said single-charge and multiple-charged surfactants being exclusively negatively-charged. 
     
     
         18 . The fuel additive composition according to  claim 17 , wherein said non-ionic surfactant comprises a polyoxyethylene-n-octylphenyl ether or a polyoxyethylene-n-dodecylphenyl ether containing 4 to 6 oxyethylene moieties. 
     
     
         19 . The fuel additive composition according to  claim 17 , wherein said ionic surfactant comprises a negatively-charged surfactant. 
     
     
         20 . The fuel additive composition according to  claim 17 , wherein said surfactant/stabilizer includes a nanoparticle stabilizer compound comprising at least one organic carboxylic acid or salt thereof. 
     
     
         21 . The fuel additive composition according to  claim 20 , wherein said stabilizer compound is selected from the group consisiting of 2-[2-(2-methoxyethoxy)ethoxy] acetic acid (MEEA), ethylenediaminetetraacetic acid (EDTA), lactic acid, gluconic acid, pyruvuc acid, tartaric acid, citric acid, and mixtures thereof. 
     
     
         22 . A method of making a cerium-containing fuel additive comprising the steps of:
 a) providing a mixture of a nonpolar medium, a surfactant, and a co-surfactant; and   b) combining said mixture with an aqueous suspension of cerium dioxide nanoparticles stabilized by a stabilizer or combination of stabilizers.   
     
     
         23 . The method of making a cerium-containing fuel additive according to  claim 22 , wherein the stabilized cerium dioxide nanoparticles have a hydrodynamic diameter of about 1 nm to about 15 nm. 
     
     
         24 . The method of making a cerium-containing fuel additive according to  claim 23 , wherein the stabilized cerium dioxide nanoparticles have a hydrodynamic diameter of less than about 8 nm. 
     
     
         25 . The method of making a cerium-containing fuel additive according to  claim 24 , wherein the stabilized cerium dioxide nanoparticles have a hydrodynamic diameter of about 6 nm. 
     
     
         26 . The method of making a cerium-containing fuel additive according to  claim 22 , wherein said stabilized cerium dioxide nanoparticles are prepared by the steps of:
 a) providing an aqueous first reaction mixture comprising a source of cerous ion and a nanoparticle stabilizer or combination of stabilizers;   b) stirring said first reaction mixture while adding an oxidant, thereby producing a second reaction mixture;   c) adding a source of hydroxide ion to said second reaction mixture while subjecting said second reaction mixture to mechanical shearing; thereby forming a third reaction mixture; and   d) heating said third reaction mixture to a temperature between about 50° C. and about 100° C., thereby producing said stabilized cerium dioxide nanoparticles.   
     
     
         27 . The method of making a cerium-containing fuel additive according to  claim 22 , wherein said co-surfactant comprises an alcohol. 
     
     
         28 . The method of making a cerium-containing fuel additive according to  claim 26 , wherein said nanoparticle stabilizer is selected from the group consisting of 2-[2-(2-methoxyethoxy)ethoxy] acetic acid (MEEA), lactic acid, gluconic acid, pyruvic acid, EDTA, tartaric acid, citric acid, and combinations thereof 
     
     
         29 . The method of making a cerium-containing fuel additive according to  claim 22 , wherein said surfactant is selected from the group consisting of a polyoxyethylene-n-octylphenyl ether containing 4 to 6 oxyethylene moieties, a polyoxyethylene-n-dodecylphenyl ether containing 4 to 6 oxyethylene moieties, and mixtures thereof. 
     
     
         30 . A method of making a cerium containing fuel additive according to  claim 22 , wherein said nonpolar medium is a hydrocarbon containing about six to about twenty carbon atoms. 
     
     
         31 . The method of making a cerium-containing fuel additive according to  claim 30 , wherein said nonplar medium is selected from the group consisting of octane, decane, toluene, diesel fuel, ULSD fuel, biodiesel, and mixtures thereof. 
     
     
         32 . The method of making a cerium-containing fuel additive according to  claim 26 , wherein said nanoparticle stabilizer or stabilizer combination has a log (K BC ) of between 1 and 14, wherein K BC  is the binding constant of the nanoparticle stabilizer with cerium ion. 
     
     
         33 . The method of making a cerium-containing fuel additive according to  claim 22 , wherein said stabilized cerium dioxide nanoparticles have a substantially monomodal size distribution. 
     
     
         34 . The method of making a cerium-containing fuel additive according to  claim 22 , wherein said stabilized cerium dioxide nanoparticles comprise a core and a shell, said shell including at least one transition metal that has a binding affinity for iron.