Preparation of nanoparticles by flash evaporation

Abstract

A method for preparing organic or inorganic nanoparticles by instantaneous evaporation or flash evaporation, e.g. for the manufacture of nanoparticles of fertilizers, pharmaceutical or phytopharmaceutical active ingredients, or insensitive energy materials.

What is claimed is: 
     
         1 . A device providing nanoparticles of at least one crystallized compound, comprising:
 a reactor for heating and pressurizing a solution of at least one compound comprising:
 a feed of a solution of the compound and at least one solvent; 
 a pressurizing device pressuring said solution from 3 to 300 bars 
 a heating device of said solution; 
   a spray drying chamber for atomizing the heated and pressurized solution into nanoparticles of said at least one compound in a crystallized form, said spray drying chamber comprising:
 at least one dispersion device to disperse the heated and pressurized solution at an angle ranging from 30 to 150° under pressure ranging from 0.0001 to 2 bars; 
 a solvent separating device; 
   one or more devices to recover said nanoparticles selected from the group consisting of an electrostatic separator, a cyclone and a cyclone comprising an electrostatic device, and   a vacuum pump removing the solvent in gaseous state.   
     
     
         2 . The device according to  claim 1 , wherein at least one dimension of the nanoparticles is smaller than 100 nm. 
     
     
         3 . The device according to  claim 1 , wherein the solution is at a temperature higher than the boiling point of the solvent or at a temperature higher than the boiling point of the solvent mixture at standard pressure. 
     
     
         4 . The device according to  claim 1 , wherein said device is continuous or semi-continuous. 
     
     
         5 . The device according to  claim 1 , wherein the solvent or mixture of solvents has a boiling point lower than 80° C. at standard pressure. 
     
     
         6 . The device according to  claim 1 , wherein the solvent or mixture of solvents has a boiling point lower than 60° C. at standard pressure. 
     
     
         7 . The device according to  claim 1 , wherein the heated solution is under a pressure ranging from 5 to 150 bars. 
     
     
         8 . The device according to  claim 1 , wherein the heated solution is under a pressure ranging from 10 to 60 bars. 
     
     
         9 . The device according to  claim 1 , wherein the heated solution is under pressure of an inert gas selected from the group consisting of nitrogen, argon, helium, neon and xenon. 
     
     
         10 . The device according to  claim 1 , wherein the dispersion device is selected from the group consisting of a hollow cone nozzle, a solid cone nozzle, a flat jet nozzle, a rectilinear jet nozzle, a pneumatic atomizer and a combination thereof. 
     
     
         11 . The device according to  claim 1 , wherein the dispersion device is a hollow cone nozzle. 
     
     
         12 . The device according to  claim 1 , wherein the dispersion device disperses the heated and pressurized solution at an angle of 60 to 80°. 
     
     
         13 . The device according to  claim 1 , wherein the compound is selected from the group consisting of energetic compounds, pharmaceutical compounds, phytopharmaceutical compounds, dye compounds, pigments, inks, paints and metal oxides. 
     
     
         14 . The device according to  claim 1 , wherein the solvent is selected from the group consisting of an alkane; an alcohol; a thiol; an aldehyde; a ketone; an ether; an acid ester; and an amine 
     
     
         15 . The device according to  claim 1 , wherein the nanoparticles have a size of 2 to 100 nm. 
     
     
         16 . The device according to  claim 1 , wherein the nanoparticles have a size of 5 to 90 nm. 
     
     
         17 . The device according to  claim 1 , wherein the nanoparticles have a size of 10 to 80 nm. 
     
     
         18 . The device according to  claim 1 , wherein said spray drying chamber is a flash evaporation chamber. 
     
     
         19 . The device according to  claim 1 , wherein the pressure in the spray drying chamber is obtained by a vacuum pump. 
     
     
         20 . A device comprising a vessel under high pressure for storing a solution of a solvent and at least one compound, a spray drying chamber comprising an integrated heated nozzle, one or more axial cyclones, and a vacuum pump. 
     
     
         21 . The device according to  claim 20 , wherein said vessel contains the solvent with the compound in the form of a solute, said vessel being overpressurized by compressed nitrogen. 
     
     
         22 . The device according to  claim 20 , wherein the flow rate in this device is induced by the overpressure of compressed nitrogen. 
     
     
         23 . The device according to  claim 20 , wherein said device a filter repels solid impurities in the initial solution. 
     
     
         24 . The device according to  claim 20 , wherein said spray drying chamber comprises at least one nozzle with hollow cone and electric heating. 
     
     
         25 . The device according to  claim 20 , wherein said device comprises two axial flow cyclones in parallel.