Synthesis of nanometer-sized particles by reverse micelle mediated techniques

Abstract

The present invention relates to a method of producing particles having a particle size of less than 100 nm and surface areas of at least 20 m 2 /g where the particles are free from agglomeration. The method involves synthesizing the particles within an emulsion having a 1-40% water content to form reverse micelles. In particular, the particles formed are metal oxide particles. The particles can be used to oxidize hydrocarbons, particularly methane.

1 - 71 . (canceled)  
     
     
         72 . A composition comprising: 
 a material capable of catalyzing a combustion reaction of a hydrocarbon, the material having an average surface area, after exposure to conditions of at least about 1300° C. for at least about 2 hours, of at least 20 m 2 /g.    
     
     
         73 . A method comprising effecting a reaction via introducing a water-reactive reactant in the presence of a reverse emulsion and recovering a material from the reaction having an average particle size of less than about 100 nm wherein the material, upon exposure to 700° C. for at least about 10 mins., retains a surface area of at least about 100 m 2 /g.  
     
     
         74 . A method as in  claim 73 , wherein the step of introducing the reactant comprises introducing a ceramic precursor into the reverse emulsion prior to reaction.  
     
     
         75 . A method as in  claim 73 , comprising introducing a ceramic precursor in a non-aqueous emulsion into the reverse emulsion.  
     
     
         76 . A method as in  claim 74 , wherein the ceramic precursor comprises an alkoxide.  
     
     
         77 . A method for preparing a particle, comprising: 
 providing an emulsion including a hydrocarbon, at least one surfactant and a water content of about 1-40% to form reverse micelles, the reverse micelles comprising a disperse aqueous phase;    adding at least one water-reactive reactant; and    allowing the at least one reactant to react in and with the disperse aqueous phase to form a particle having a particle size of less than about 100 nm, the particle being free from agglomeration.    
     
     
         78 . A method as in  claim 77 , wherein the particle is a metal oxide particle.  
     
     
         79 . A method as in  claim 78 , wherein the metal oxide particle is a mixed metal oxide particle comprising at least two metals.  
     
     
         80 . A method for preparing a particle, comprising: 
 providing an emulsion including a hydrocarbon, at least one non-ionic surfactant and a water content of about 1-40% to form reverse micelles, the reverse micelles comprising a disperse aqueous phase;    adding at least one reactant; and    forming a particle having a particle size of less than about 100 nm, the particle being free from agglomeration.    
     
     
         81 . A method comprising coating a particle within a micelle.  
     
     
         82 . A method as in  claim 81 , wherein the particle is coated with a metal oxide layer.  
     
     
         83 . A method as in  claim 81 , wherein the micelle is a reverse micelle.  
     
     
         84 . A method as in  claim 81 , wherein the particle is a metal oxide particle.  
     
     
         85 . A method comprising: 
 providing a composition having a surface area of at least 20 m 2 /g after exposure to conditions of at least 1300° C. for at least 2 h; and    oxidizing a hydrocarbon.    
     
     
         86 . A method as in  claim 85 , wherein the composition comprises particles having a particle size of less than about 100 nm.  
     
     
         87 . A method as in  claim 85 , wherein the hydrocarbon is selected from the group consisting of methane, ethane, propane and butane.  
     
     
         88 . A method as in  claim 85 , wherein conversion of the hydrocarbon is at least 10% at 400° C.  
     
     
         89 . A method as in  claim 88 , wherein at least 90% of the conversion is sustained at 1100° C. for at least 2h.  
     
     
         90 . A method comprising oxidizing at least one hydrocarbon in the presence of at least one non-noble metal oxide having a particle size of less than about 100 nm.  
     
     
         91 . A method as in  claim 90 , wherein the metal oxide has a surface area of at least about 20 m 2 /g.  
     
     
         92 . A method as in  claim 76 , wherein the alkoxide comprises barium alkoxide.  
     
     
         93 . A method as in  claim 77 , wherein the water-reactive reactant comprises a ceramic precursor.  
     
     
         94 . A method as in  claim 93 , wherein the ceramic precursor comprises an alkoxide.  
     
     
         95 . A method as in  claim 94 , wherein the alkoxide comprises barium alkoxide.