Synthesis outside high and low temperature equilibrium by spray flash synthesis

Abstract

The invention relates to a chemical synthesis method, the said method comprising Spray Flash Evaporation, also commonly referred to by the corresponding initialism SFE, which comprises the chemical reaction of at least one first compound with at least one second compound, under conditions in which the first compound and the second compound react to form at least one third compound. The invention also relates to a device for implementing this method and the compounds obtained by this method.

Claims

1. A chemical synthesis method, said method comprising a Spray Flash Evaporation, also commonly referred to by the corresponding initialism SFE, which comprises the chemical reaction of at least one first compound with at least one second compound, under conditions in which the first compound and the second compound react to form at least one third compound, said method including the following steps (a) to (d): (a) the preparation of a first liquid phase comprising the first compound in order to form a first liquid composition placed in a first tank, and the preparation of a second liquid phase comprising the second compound that forms a second liquid composition placed in a second tank; (b) the heating of the first composition, under a pressure P1, at a temperature that is higher than the boiling point of the liquid, and the heating of the second composition, under a pressure P1, at a temperature that is higher than the boiling point of the liquid; and (c) simultaneous atomisation of the first and second compositions heated under pressure, in an atomisation chamber by means of at least one dispersion device under a pressure P2 that is lower than Pl and P1; and (d) obtaining said third compound by reacting of the first compound and the second compound.

2. The preparation method according to claim 1, wherein the method includes the formation of particles comprising the said third compound.

3. The preparation method according to claim 1, wherein the method further comprises, after step (d), the following step (e): (e) the recovery of the third compound.

4. The preparation method according to claim 1, wherein the first compound and/or the second compound are independently liquid or solid or gaseous.

5. The method according to claim 1, wherein, independently, the first and the second liquid phases comprise or are constituted respectively, of the first compound in liquid form, optionally after dissolution in a solvent, or in solid form dispersed in a solvent, and/or of the second compound in liquid form, optionally after dissolution in a solvent, or in solid form dispersed in a solvent, the solvents of the first and second liquid phases possibly being identical or different.

6. The method according to claim 1, wherein the third compound is obtained in the form of particles.

7. The method according to claim 6, wherein the method includes the final recovery of particles comprising the third synthesised compound, by means of one or more retention devices for retaining particles, selected from a filter, an electrostatic separator, a cyclone, a cyclone comprising an electrostatic device and a filter.

8. The method according to claim 6, wherein at least one dimension of the particles is less than 100 nm.

9. The method according to claim 6, wherein the greatest dimension of the particles are ranging from 5 to 100 nm.

10. The method according to claim 6, wherein the greatest dimension of the particles are ranging from 10 to 30 nm.

11. The method according to claim 1, wherein the reaction is carried out by heating the first compound and the second compound, whether or not independently of one another, and in that the heating is carried out under a pressure ranging from 5 to 150 bars.

12. The method according to claim 11, wherein the heating is carried out under a pressure ranging from 10 to 60 bars.

13. The method according to claim 1, wherein the reaction is carried out by heating the first compound and the second compound, whether or not independently of one another.

14. The method according to claim 13, wherein the reaction is carried out under pressure of an inert gas.

15. The method according to claim 14, wherein the inert gas is selected from nitrogen, argon, helium, neon, xenon, sulfur hexafluoride (SF.sub.6), and chlorofluorocarbon (CFC).

16. The method according to claim 1, wherein the atomisation of the one or more composition/s is, independently, carried out at a pressure ranging from 0.001 to less than 1 bar; and/or at an angle of 60 to 80.

17. The method according to claim 16, wherein the pressure is ranging from 0.02 to 0.2 bar.

18. The method according to claim 1, wherein the compounds are selected from energetic compounds, pharmaceutical compounds, phytopharmaceutical compounds, medical contrast compounds, fluorescent compounds, optical compounds, dye compounds, aromas and flavouring agents, fragrances (perfume), pigments, inks, paints, metals, metal oxides, semiconductor compounds, optical compounds, optoelectronic compounds, ferroelectric compounds, non-linear response compounds or bio-electronic compounds.

19. The preparation method according to claim 1, wherein, in step (b), P1 and P1, which may be equal or different, are ranging from 3 to 300 bars.

20. The preparation method according to claim 1, wherein, in step (c), P2 is ranging from 0.0001 to 2 bars.

21. The preparation method according to claim 1, wherein step (c) is carried out under heating conditions.

22. The preparation method according to claim 21, wherein step (c) is carried out at a temperature of between 20 C. and 2000 C.

Description

FIGURES

(1) FIG. 1 is a schematic representation of the device of the invention for the production of the synthesised compounds, in particular in the form of particles.

(2) FIG. 2 represents the scanning electron microscopy images of TiO.sub.2 particles formed via the method according to the invention before calcination (A, B and C) and after calcination (D, E and F).

(3) FIG. 3 represents the transmission electron microscope images of bismuth titanate particles obtained by the method according to the invention before calcination (A and B) and after calcination (C and D).

(4) FIG. 4 is an X-ray difractogram produced on a bismuth titanate powder prepared by the method according to the invention and after calcination.

EXAMPLES

Example 1: Synthesis of MOFs (Metal Organic Frameworks)

(5) MOFs are of great interest in the field of energy storage.

(6) In this example, the synthesis of the coordination polymer (MOF) referred to as HKUST-1 is illustrated.

(7) The synthesis is carried out using an installation according to the invention that comprises two nozzles, which spray towards one another. One nozzle sprays a solution of Cu(NO.sub.3).sub.2 with a concentration of 3.3 grammes per litre of acetone. The second nozzle sprays a solution of BTC (1,3,5-BenzeneTriCarboxylic acid) with a concentration of 1.85 grammes per litre of acetone.

(8) Temperatures of the two nozzles: 160 C.

(9) Pressures in the two nozzles: 40 bar.

(10) Pressure in the atomisation chamber: 7 mbar. The reduced pressure is obtained by means of a vacuum pump in communication with the atomisation chamber.

(11) Using the SFS method fine particles of the MOF HKUST1 are obtained which have the chemical formula:

(12) ##STR00001##

(13) The conventional techniques which use for example atomisation (commonly referred to as spray-drying) or an autoclave technique provide particles of micrometric sizes while the invention provides the means to obtain particles of smaller sizes, typically whereof the individual unit particles have one greater/greatest dimension that is less than 200 nm. They are able to form agglomerates of greater dimensions.

(14) It is possible for the particles to be continuously prepared by a system or method according to the invention.

Example 2: Synthesis of Titanium Dioxide (TiO.SUB.2.)

(15) TiO.sub.2 is very widely used in photocatalysis and in the energy field in general. In this example, the synthesis of particles of titanium dioxide is illustrated.

(16) The synthesis is carried out using an installation according to the invention that comprises two nozzles, which spray towards one another. One nozzle sprays a solution of 1% mass concentration of Titanium Tetra Isopropoxide (TTIP) in isopropanol. The second nozzle sprays water.

(17) Temperatures of the two nozzles: 160 C.

(18) Pressures in the two nozzles: 40 bar.

(19) Pressure in the atomisation chamber: 20 mbar. The reduced pressure is obtained by means of a vacuum pump in communication with the atomisation chamber.

(20) Using the SFS method the according to the invention fine particles of TiO.sub.2 are obtained. Conventional techniques provide nanometric particles. An installation or method according to the invention provides the means to obtain even finer particles. It is generally necessary to provide an electrostatic precipitator in order to collect these particles of small nanometre sizes (typically less than 20 nm as measured by atomic force microscopy or AFM, for example).

(21) The invention makes it possible to limit impurities, in particular as compared to conventional sol-gel methods.

Example 3: Synthesis of Titanium Dioxide (TiO.SUB.2.) by Hydrolysis of an Alcoholate

(22) Another example is the hydrolysis of titanium isopropanolate (TTIP) in order to produce titanium dioxide.

(23) For this, a first solution composed of TTIP dissolved in isopropanol of High Performance Liquid Chromatography (HPLC) grade, is introduced into one of the tanks at a concentration of one percent by mass; a second solution, consisting of isopropanol and water, is placed in the other tank. The quantity of water introduced is fixed in a manner so as to have TTIP/H.sub.2O molar ratios equal to 1:1, 1:2 and 1:4.

(24) The two solutions are mixed in a device placed upstream from the nebulisation nozzle, the temperature of which is maintained at 160 C. The reaction medium is then injected into the atomisation chamber.

(25) Pressure in the nozzle: 40 bar.

(26) Pressure in the atomisation chamber: 5 to 20 mbar. The reduced pressure is obtained by means of a vacuum pump in communication with the atomisation chamber.

(27) All three of the powders recovered are amorphous, composed of elementary particles, the average diameters of which, as measured on scanning electron microscopy images (FIGS. 2, A, B and C), are typically submicrometric.

(28) The subsequent calcination in air, at a temperature of 400 C., for a period of 4 hours, provides anatase powders (TiO.sub.2), formed of particles having submicrometric diameters (FIGS. 2, D, E and F).

(29) The morphological and structural characteristics of the submicrometric powders obtained by the method according to the invention before and after calcination are reported in the table below.

(30) TABLE-US-00001 After Calcination Before Calcination Specific Average Average Area Diameter Diameter (m.sup.2/g, TTIP:H.sub.2O of of BET (mol:mol) Particles Structure Particles Method) Structure 1:1 180 Amorphous 190 12 Anatase 1:2 170 Amorphous 139 15 Anatase 1:4 162 Amorphous 155 14 Anatase

Example 4: Synthesis of Bismuth Titanates

(31) Another example is the synthesis of bismuth titanates by the method according to the invention.

(32) In this case, a solution of bismuth nitrate (BN) in acetone, also containing acetic acid and water, is placed in a first tank. A solution of titanium isopropanolate (TTIP) in isopropanol is placed in a second tank. The two solutions are mixed in a device placed upstream from the nebulisation nozzle, the temperature of which is maintained at 160 C. The reaction medium is then injected into the atomisation chamber. Pressure in the nozzle: 40 bar.

(33) Pressure in the atomisation chamber: 5 to 20 mbar. The reduced pressure is obtained by means of a vacuum pump in communication with the atomisation chamber.

(34) Depending on the BN/TTIP molar ratio, different bismuth titanates may be produced.

(35) The Energy Dispersive X-Ray Spectroscopy (EDS) analyses, carried out with a transmission electron microscope on a titanate sample produced by the method according to the invention, show that the two metallic elements (Ti and Bi) are mixed with very minute matter, on an atomic scale (FIG. 3, B). Calcination in air at 650 C., for a period of 4 hours, causes the formation of a titanate, possibly with a segregation of phases (FIG. 3, D), when the titanium or bismuth are in excess relative to the stoichiometry of the titanate.

(36) The X-ray diffraction carried out on the calcined samples (in air, at 650 C., for period of 4 hrs) clearly shows the crystallisation of titanate, in this case Bi.sub.2Ti.sub.2O.sub.7 (FIG. 4).

(37) Other examples of implementation of the invention are as follows: 1) Esterification reactions, Synthesis of nitrocellulose; 2) Nitration reactions; 3) Hydrolysis of alkoxides for the synthesis of oxides (eg Ti alkoxides); 4) Precipitation reactions (acid/base reaction), eg Picrates; 5) Complexation reactions (metal/ligands); 6) Synthesis of conductive polymers; 7) Synthesis of oxides; 8) Synthesis of ceramics.