DE102004038029A1 - Continuous precipitation of nanoscale products comprises chemical precipitation or solvent-nonsolvent precipitation of primary particles by rapid mixing of liquid streams in a continuous reactor - Google Patents

Abstract

Continuous precipitation of nanoscale products comprises chemical precipitation or solvent-nonsolvent precipitation of primary particles by rapid mixing of liquid streams in a continuous reactor and optionally coating or surface-modifying the particles by chemical precipitation or coprecipitation within a short time and space. Independent claims are also included for: (1) apparatus for continuous production of nanoscale products in a microreactor, where electrically conductive particles, or layers or bodies thereof, are produced from nanoparticles or microparticles coated with tin or zinc oxide together with indium, aluminum, manganese or antimony oxide by precipitation; (2) apparatus for continuous production of nanoscale products in a microreactor, where the particles are used as fillers for plastics and lacquers or for producing solids for ceramic products, for producing conductive bodies or layers, for producing scratch-resistant bodies or layers, for producing electroceramic products, for producing catalysts or explosives; (3) apparatus for continuous production of nanoscale products in a microreactor, comprising a non-plugging chemical microreactor used for chemical conversions that may unintentionally result in precipitation or incrustation.

Description

The The present invention relates to a method and associated apparatus for the continuous production of morphologically uniform, nanoscale stabilized products with narrow particle size distribution by precipitation in clog-free microreactors and in definable, temporal Spacing surface modification.

background The object of the present invention is the fact that at felling the chemical composition, physical structure, morphology and also the structural homogeneity of the precipitating particles on diverse Way can be influenced.

To the Achieve as possible small particle size is the Energy balance of the resulting particles of crucial importance. The energy of a particle is composed of the crystallization liberated lattice energy and the energy to be applied resulting surface. For very small crystallites is so small and liberated grid energy the surface energy to be applied comparatively high, that the molecules prefer to be in the dissolved state remain. Only for larger crystallites, consisting of a critical number of molecules becomes the total energy Cheap. The crystallites grow so only as soon as the critical number of molecules, from which the crystallite formation is energetically favorable, is exceeded. With the Help of surface modifiers let yourself the surface energy to be applied but decrease. Thus, the critical number of molecules from which the Crystallization energetically favorable is, lowered.

For the particle size distribution plays first the speed of mixing is crucial. at a rapid chemical precipitation in a stirred reactor is the mixing rate at which the reactants mix become slower regularly as the nucleation rate. In addition, occur in such Reactor already diffusion-controlled precipitated particles constantly with freshly added reactants and also with the resulting germs in contact. This ultimately leads to an uncontrollable particle growth and different Particle sizes.

The precipitation in such a stirred reactor means but continue that the emerging germs in one yet completely mixed, so inhomogeneous environment arise. Inhomogeneous environment means the existence of gradients in terms of pH and also the concentrations of reactants and already formed germs or already formed, larger particles. As with different pH values frequently form different particle morphologies, means the precipitation in the stirred reactor ie the formation of particles with a broad particle size distribution and that the individual particles additionally have a morphologically heterogeneous Structure may have.

considered one the co-precipitation of mixed metal oxides, such as, for example, in the form of indium tin oxide, Antimony tin oxide, indium zinc oxide, antimony zinc oxide for electrical conductive Coatings or electroceramics in general or other mixed metal oxides, the for many applications are needed, for example, in catalysis, is the problem of too slow mixing in the production by precipitation in stirred reactors clear. Leading such co-precipitation for example, by dropping an acidic reactant solution into a basic reactant solution or vice versa, results even with vigorous stirring within the drops a pH gradient that causes an inhomogeneous precipitate, as the different metal oxides or metal hydroxides at different pH values fail.

Farther especially in the precipitation of nanometer size Particles immediately after the precipitation chemical and physical substance changes instead, which significantly affect the properties of nanoparticles can. So can by Ostwald ripening larger particles grow at the expense of smaller particles that completely disappear can.

Especially but are also the interactions of the particles with each other Importance. Van der Waals forces are the root cause of processing problems Nanoparticles. Between like particles they are always attractive and lead thus to the agglomeration. they hang linear from the particle diameter and therefore take less As the diameter decreases much less than the mass forces, so that they eventually dominate at small diameters.

The substance specific Hamakerkonstante is a size for the calculation of these forces. However, the hamburger constant depends on the dielectric constants ε _{T of} the particles and the dispersion medium ε _M and increases with their difference (ε _T - ε _M ), which is inevitably greater in air than in liquids. Therefore, the Van der Waals interaction is significantly smaller for ceramic particles in water than in air. Accordingly, particles that are initially isolated and then surface-modified for stabilization, are dry powder in a potential minimum and are subsequently only with great effort to separate again.

The industrially currently the most widely used methods of production nanoparticles from gas phases or pyrogenic processes cause the high van of the Waals forces in air inevitably to agglomerated products. additionally to lead the inevitably high temperatures in the pyrogenic process too irreversible agglomerations. That these methods are industrial yet the most used methods are and even further The reason for this is that these processes are directly salable products to lead and wet chemical methods for precipitation of nanoparticles have so far usually not led to optimal results.

reason for that is in case of precipitation, in addition to those already mentioned Disadvantages of using stirred reactors, usually a weakening of the electrostatic repulsive forces and an insufficient one steric stabilization of the precipitated Particles.

The weakening which has electrostatic repulsive forces a cause in that of chemical reactions in the solvent mostly, in addition to the felled Particles, dissolved Companion salts are formed. These companion salts influence the stability of nanoparticle dispersions negative in that it significantly reduces the electrostatic repulsive forces (double layer repellency) to reduce. For workup must these companion salts also separated by filtration and washing become. Especially when filtering then there is a risk of Agglomeration of nanoparticles into larger particle assemblies.

A Another cause arises from the fact that in particular in stirred reactors with inhomogeneous pH environment, some of the resulting during precipitation Particle is located at the isolelectric point where the electrostatic rejection is minimal.

It an object of the present invention was a technically useful, continuous process to find that precipitation with a very fast mixture and high supersaturation.

It was also target, precipitations in aqueous media to do so that the resulting particles in the precipitation medium with hydrophilic surface modifiers so surface-modified be that by steric stabilization by means of surface modifiers despite the presence of accompanying salts, an agglomeration of the particles can not take place anymore.

Farther it was also goal felling in aqueous To do media like that, that by a simultaneously taking place to the actual precipitation treatment with hydrophobic surface modifiers the resulting particles in the precipitation medium be rendered hydrophobic and from the accompanying salt-containing, aqueous Phase can be separated into a separate organic phase.

Farther It was also an object of the present invention, precipitates in aqueous To do media like that, that by the choice of the reactants no companion salts arise.

All in all It was in general objective of the present invention, a To find methods and apparatuses with which the Properties of the precipitation arising particles can be optimally controlled and also in the onset understood particles and then the already formed particles in terms of their further transformation and a controllable further processing can be optimally influenced.

An important part of the objective was to be able to fan out the speeds for mixing, nucleation and particle growth as far as possible and in a targeted manner. The mixing speed should be as much as possible greater than the nucleation rate and the growth rate should be as much as possible smaller than the nucleation rate
(Mixing speed> nucleation rate> growth rate)

This The aim is by means of an industrially usable method and the associated Achieves devices with which the properties of particles, the case of precipitation arise, can be controlled in a targeted manner.

Of the first step is influencing the chemical structure, physical structure, morphology and also structural homogeneity the case of precipitation first germs by the very fast mixing in a continuous working reactor, preferably a clog-free microreactor.

Thereby manages the mixtures resulting from uncontrolled precipitations to avoid specifically from morphologically different precipitation products and the reaction sequence selectively in the direction of each sought To direct morphology.

In such a microreactor can about it In addition, in a precipitation, which is carried out according to the prior art in an aqueous environment, in addition a water-miscible solvent are added, which reduces the solubility of the precipitate and thus can lead to even faster precipitation and even smaller particles. Such a precipitation can be carried out, for example, by means of an acid and a lye or a salt and a lye or an acid. The solvent may in this case be added to at least one of the aqueous reactant solutions or it may preferably be subsequently admixed in a microreactor in the mixing zone of the reactants or particularly spatially subsequently and thus in operation, ie in practice at a close distance, as the third component.

When Example is the classical precipitation of alkali metal silicates with Acids. According to the invention this precipitation by continuous feeding of the reactants for mixing carried out in a clog-free microreactor and thereby either the acid a proportion of a water-miscible solvent, preferably alcohol attached. The water-miscible solvent can over a separate third Reaktandeingingang be added. By the alcohol content it comes to a more spontaneous precipitation without the usual Training of crosslinked polymer structures.

simultaneously can this solvent at least one surface modifier, in particular a non-water-soluble Surface modifier included. The surface modifier, when mixing the solvent in water-miscible solvent in one for the actual precipitation simultaneous solvent nonsolvent precipitation forms a nanoemulsion, deposits directly on the surface of the resulting precipitates hydrophobiert this and causes the resulting particles can be absorbed in organic phases.

It but can also at least one of the leading to the precipitation of particles Reactants may be dissolved in a water-miscible solvent while at least one reactant as a reactant in an aqueous Phase is located. This procedure can be chosen, for example, in the precipitation in the microreactor of zinc salt dissolved in alcohol, such as zinc acetate or zinc chloride by reaction with a base. The advantage with this procedure arises from the possibility of the water-miscible solvent for simultaneous introduction of a hydrophobic surface modifier to use.

It But also, according to the so-called sol-gel technique, water be yourself reactant. In this case, it is possible that at least a water-hydrolyzable reactant, such as a Metal alkoxide in a dry, water-miscible solvent and the second reactant, namely water (possibly together with a percentage of acid or lye for hydrolysis acceleration) are also in one water-miscible solvent located. For example, titanium tetraisopropylate dissolved in dry Isopropanol, in a microreactor with a low water content isopropanol reacted. Also with this procedure arises the possibility, the water-miscible solvent for simultaneous introduction of a hydrophobic surface modifier to use in the sense below.

It but can also at least one metal salt in a solvent organic solvent be reacted with a base in an organic solvent. As an example, an alcoholic zinc acetate solution with an alcoholic solution reacted by lye, for example ammonia. Also with this procedure results in the possibility the water-miscible solvent for simultaneous introduction of a hydrophobic surface modifier to use in the sense below.

Provided it is in the procedures described in the precipitated dispersion around particles in a solvent mixture Made of water and water-miscible solvent can be used to obtain a dispersion in organic medium distilled off the excess water azeotropically or it becomes an organic medium with a boiling point selected the higher than that of water, for example monohydric or polyhydric alcohols, and the water is distilled off.

Suitable for industrial production of the described precipitation reactions are in principle all flow reactors, Y-mixers or T-mixers, but especially microreactors, but primarily microreactor embodiments in which it can not lead to clogging of narrow channels of the microreactors. Some embodiments are described in this application. Well suited are reactors like in EP 1165224 described.

In otherwise conventional microreactors, which are usually constructed as so-called "multi-channel" systems, each reactant feed is divided into a plurality of individual channels, and the content of each individual channel then reacts with the supplied content of the associated channel of the reaction component Lengths of the channels and the relatively imprecise channel dimensions make it impossible to convey even approximately equal amounts of reactants across all parallel channels, leading to unreliable and uncontrollable drawbacks in the stoichi ometry of the reaction in the individual channels, even if the total stoichiometry, ie the sum of the reactant streams of the "multi-channel" system is maintained.

Particularly suitable for the method according to the invention is an embodiment in which EP 1165224 , Nozzles are made of hard materials, such as sapphire, ruby or diamond. These nozzles preferably have only a very short channel length of usually between 0.5 and 2 mm. Because of this very short channel length, the flow resistance through the nozzle is relatively low. Thus, according to the invention, as "single-channel" systems, these can be operated at high pressures to achieve high throughput rates, preferably pressures of> 10 bar, particularly preferably> 30 bar, being built up from the high pressure and pressure The low nozzle resistance results in that the total delivery through a single nozzle is comparable to the delivery rate of a plurality of channels in a "mult-channel" system. Since these nozzles are also produced with high precision and reproducibility in terms of their diameter, several such "single-channel" reactors can additionally be operated in parallel, without the stoichiometric uncertainties and errors customary in the "multi-channel" systems being encountered.

through Such microreactors succeed in terms of apparatus, the mixing speed to increase so that the mixture of the precipitate leading Reactants complete before nucleation for particle formation begins and without it comes to reactor blockages. How to get there reproducible and on an industrial scale to finely divided dispersions with homogeneous size distribution and high phase purity. Essential part of the present invention is the possibility in the fast precipitation reaction expire nucleation in a "pH homogeneous" environment to let, so a targeted adjustment of a desired pH in the itself continuously forming reaction solution. The mixture and that the setting of a desired "pH homogeneous" environment takes place so within the very short time, in the maximum supersaturation prevails and no nucleation has yet occurred.

On This way you can also by example, the mixture of at least two metal salts, acids or bases in each case in one of the two reaction solutions simultaneously precipitate at least one second product simultaneously, the precipitated products may have different isoelectric points, so it is between the To precipitation products a heterocoagulation occurs, which is used to coat a particle species can use with another. In this case, the second precipitated product as an adjuvant for the processing of the first serve, for example as a sintering additive. A typical example of the second precipitate is magnesium oxide. But there are also a whole series of mixed metal oxides in question, as they are then used as catalysts or electroceramics can be.

considered one the co-precipitation of mixed metal oxides, such as, for example, in the form of indium tin oxide, Antimony tin oxide, indium zinc oxide, antimony zinc oxide for electrical conductive Coatings or electroceramics in general or other mixed metal oxides, the for many applications are needed, for example, in catalysis, succeeds in setting a homogeneous precipitation environment that is too homogeneous and phase-pure mixed oxides or mixed hydroxides leads. Additionally or alternatively to oxides also other precipitation products like Sulfides, sulfates, phosphates or borates can be produced.

These Procedure of simultaneous precipitation several oxides can be, for example, for the production of use nano-glass or nano-enamel, in which case the resulting homogeneous mixture of oxides desired, causes low melting temperatures. There may be several different ones Reactants in a reaction solution or the reactants can in own reaction solutions over several Nozzles or channels each separately supplied to the mixing point.

at an execution the invention used Plant engineering will do the pumps, which will promote the flow of reactants into the microreactor serve, preferably by means of a conductivity or pH sensor regulated at the product output and a controller. The dosage can but also regulated by means of differential feeders or flowmeters become.

The pH adjustment is done by varying the stoichiometry of the reactants or the addition of additional Acid or Lye. The pH regulating acid or alkali or a salt may be part of the reaction system or only for conditioning serve the pH and mixed for this purpose at least one reactant. For electrostatic stabilization of the resulting particles is it is most beneficial when the pH in the resulting dispersion at least 2 full pH steps away from the isoelectric point located.

Of the Period until complete Mixing is in such a microreactor, depending on nozzle widths, Pump pressure, reactant viscosity, temperature and other parameters usually below one millisecond.

The procedures described herein for the preparation of nanoparticulate precipitation products can changed so be that in at least one of the reactant solutions additionally nanoparticles or microparticles before being prepared in this way Dispersion in the microreactor with at least one further reactant solution for Reaction is brought.

The The procedures described here may also be modified that at least one of the reactant solutions with a particle dispersion is mixed and the dispersion prepared in this way in the Microreactor with at least one further reactant solution for Reaction is brought. Mixing the reactant solutions with However, dispersion can also take place in a microreactor. The microreactor may be the microreactor used for the precipitation upstream or used for precipitation microreactor can be an extra Reactant input through which the dispersion of the reactants in the Mixing point is added. In this case one can a Auffällung one Nanoparticle layer on the dispersed nanoparticles or microparticles to reach. The dispersed particles may also be metallic or inorganic platelets or structured particles, such as flakes or mica act.

Such Reactors can also according to the invention be operated that laterally on the supply channels for the reactants or in the mixing zone additional inlets located, by which rinsing liquids or purge gases for purifying the reactor can be.

The flushing medium can also over to register an input in a pipe-in-pipe-in-pipe system, prefers over the "middle one" in In this case, three feed channels. The feed pressure for that over a check valve supplied flushing medium can be advantageously set so that the Check valve opens as soon as the feed pressure for the Reactants after switching off the reactants supplying Pumps drops.

Of the second essential aspect of the present invention is modification the surfaces the at the precipitation resulting particles by a chemical or physical reaction with at least one surface-modifying Reagent for influencing the growth behavior or the agglomeration behavior. Especially in the case of precipitated products with a slightly lower nucleation rate, it may be necessary to reduce the growth rate.

These Modification of the surfaces can in the process according to the invention at the same time or at a definable time interval from Precipitation done and thus allows the definable control of the growth of the precipitated particles.

at After steric stabilization by surface modification, macromolecules are adsorbed on the surface. The surface layers must be there far wider than the Van der Waals forces. The best are Polymers which over have two different types of functional groups, of which one for the adsorption on the particle, the other for the alignment of the molecular chain in the liquid provides.

simultaneously However, this procedure also offers the advantage that the surface modifier primarily reactions with the surface of an already precipitated particle comes in and not with one of the two reactants. This is the example of precipitation of iron oxide from the reaction of aqueous iron sulfate solution with aqueous Lye explains for example, a carboxylic acid as a surface modifier is used. Due to the staggered addition of the carboxylic acid attacks this not in the stoichiometry the implementation of the iron sulfate solution with lye, so that iron carboxylate is not already at the actual Precipitation, but only on the surface the resulting particles is formed.

It is possible the previous precipitation to do so that after the precipitation pH value, which is such a large distance to the isoelectric Point of the precipitated Has particles, namely At least two pH steps that cause the particles due to this do not coagulate resulting electrostatic stabilization and that then a surface modification by sterically acting reagents and only after successful steric stabilization with a surface modifier for further processing required pH value is set.

It at least one reagent, preferably several reagents are added, which by chemical or physical reaction binds with the existing particle surface enter and optionally an additional surface coating with by precipitation incurred solids. This surface treatment can be repeated several times be performed sequentially with the same or different reactants.

In this case, the precipitation products for surface modification can be reacted as a dispersion with at least one suitable reaction partner, which binds to the surface of the precipitation products or the precipitation products in a short time interval with at least two suitable mitein reacting other reactants, resulting in further precipitation and coating of the original precipitated products.

Come for this all such reactions in question, as in the prior art already in use, but not yet for implementation in the inventive method Microreactors are known.

This are, for example, reactions with phosphoric acid or a salt of phosphoric acid or an organic phosphorus compound, water-soluble Sulfide, sulfate or borate. Furthermore for the production of metal oxide Coatings, such as silicates using silica whose water-soluble Salts or silica sol, as well as other metal oxide coatings using inorganic and organic salts, acids and Alkalis for direct coating of the precipitated products, as well as their Reaction products with a suitable reaction partner for the production of the precipitated Coating layers on the precipitation products.

Cheap is it, in order to avoid the formation of accompanying salts, reactions of inorganic acids with metal hydroxides, metal hydrogen carbonates or metal carbonates perform.

Cheap is This also a method in which by the precipitation simultaneously another precipitate with sought after, functional properties, which is optional serve as a surface modifier can. Well suited for that for example, the reaction of metal sulfate with barium hydroxide or Bariumhydrogencarbonat.

In One application is organic pigments, which can only be dissolved in sulfuric acid. in a microreactor by dilution with an aqueous solution as a solvent nonsolvent precipitation. If you add the aqueous solution Barium hydroxide, the resulting pigment particles are through the simultaneous barium sulphate precipitation filled. In this way, organic pigment particles with a large surface and produce low colorant consumption. Similarly, nanoparticle dispersions, preferably fresh or simultaneous like in the production of Colorants can be used by chemical reaction instead of water.

In another application in the latex polymerization instead of the aqueous solutions nanoparticle dispersions, preferably fresh or simultaneous like, used instead of water become. The surface modification The inorganic particle surfactants can equally as Surfactants for serve the latex stabilization. Provided the nanoparticles are salt-free like The latices are more stable against refraction.

Vice versa By refraction of the latices one arrives also with nanoparticles filled Plastics, wherein the refraction of the prior art for latex emulsions can be done.

In an execution the process uses the possibility to carry out of precipitations, in which no accompanying salts arise, in the form that in one Reaction of metal sulfate, for example iron sulfate, with the hydroxide another metal, for example, barium hydroxide, that at the same time In the exemplary case, iron oxide and barium sulfate are precipitated.

optional can additionally sulfuric acid be used. The amount of barium hydroxide used is then according to a correct stoichiometry for complete reaction or precipitation increased all reactants used. This will change the proportion to barium sulfate in the product mixture of the precipitated products accordingly elevated.

The following equation describes this precipitation for zinc oxide particles. n ZnSO ₄ + m H ₂ SO ₄ + n + m Ba (OH) ₂ > n ZnO + n + m BaSO ₄

There is the possibility that all reactants are mixed together for precipitation in the microreactor, or that they are added offset. Accordingly, for example, a reactant solution of zinc sulphate is first mixed in a microreactor with a solution of excess barium hydroxide, and the sulfuric acid required for stoichiometrically complete conversion is added only in a defined time, in terms of apparatus, spatial distance. This according to the following equation: n ZnSO ₄ n + m Ba (OH) ₂ > n ZnO ₂ + n BaSO ₄ and subsequent time-delayed addition of m H ₂ SO ₄ and their reaction with unreacted barium hydroxide to give BaSO ₄

These Procedure is favorable, because so the zinc oxide precipitation can proceed in a basic environment, causing the formation of zinc hydroxysulfate, which can form in an acidic and neutral environment becomes. In this way, barium sulfate-coated zinc oxide is formed.

Conversely, it is possible, for example, first to mix sulfuric acid with an excess amount of barium hydroxide and zeitver To add metal sulfate, which initially produces barium sulfate particles, which are then coated with metal oxide barium sulfate.

Replacing part of the zinc sulphate with antimony sulphate leads to electrically conductive particles. When zinc sulfate is used, a mixture of barium sulfate and, depending on the precipitation conditions, zinc hydroxide or zinc oxide is formed. The transition from zinc hydroxide to zinc oxide can also be carried out in a subsequent treatment step. The mixture of barium sulfate and zinc oxide can be used, for example, as a filler for plastics or paints, with zinc oxide being able to serve as a transparent ultraviolet light filter. n ZnSO ₄ + n Ba (OH) ₂ > n ZnO + n BaSO ₄

Also particularly suitable is the reaction of iron sulfate (in oxidation states 2 and 3) with barium hydroxide. The proportion of resulting barium sulfate can be increased by the proportion of sulfuric acid according to the following equation. n FeSO ₄ + m H ₂ SO ₄ + n + m Ba (OH) ₂ > n½ Fe ₂ O ₃ + n + m BaSO ₄

at The reaction forms a mixture of barium sulfate and depending on Precipitation Conditions Iron hydroxide or iron oxide.

used one forms iron (III) sulfate nanoparticles from barium sulfate and red hematite. used Instead of hematite, iron (II) sulfate is converted into iron (II) hydroxide and iron from oxygen supply or air supply according to the description according to the invention a gas-flushed microreactor yellow goethite. If one uses a mixture of iron (III) sulfate and Iron (II) sulfate gives rise to black magnetite, an oxide with the mixed ones Oxidation levels 2 and 3. Due to the preparation according to the present Invention, this magnetite has a very small particle size of below 6 nm and is superparamagnetic. By oxidation, this can be done in which are also superparamagnetic brown maghemite transferred. The mixture of barium sulfate and iron oxide can, for example, as filler for plastics or varnishes, the iron oxide serving as coloring transparent pigment and at the same time transparent filter for ultraviolet Light or as a superparamagnetic filler can come.

It can also other metal sulfates, such as aluminum sulfate or Titanyl sulfate or titanic acid be used. The inventive method leads dependent on from the selected ones pH conditions to corresponding phase-pure hydroxide or oxide.

It but it is also possible to repeat this reaction in at least one downstream reactor, wherein in one reactor, a barium sulfate precipitation in the other at least a co-precipitation takes place.

These The procedure described here using the example of iron oxide can also be used performed with other metals become. Instead of the sulfates can also Hydrogen sulfates are used.

Instead of Of barium hydroxide, other hydroxides can be used. Because of the mostly bad solubility the hydroxides in water can but prefers the more water-soluble instead of the hydroxides Hydrogen carbonates are used. The leading to insoluble precipitated products Hydrogen carbonates are usually more soluble than the corresponding ones otherwise also usable carbonates.

To Phosphates instead of sulfates can be obtained analogously to the above Executions by the use of phosphoric acid instead of sulfuric acid. In the microreactor, for example, the salt-free salt-free production is achieved of nanoscale calcium hydroxyapatite from the reaction of aqueous phosphoric acid with calcium hydrogen carbonate. Or it succeeds, for example, the precipitation of nanoscale zinc magnesium phosphate.

To the Obtaining a dispersion in organic medium may be water-miscible in the precipitation solvent be used alone or with water or it will be water miscible solvent later added and the excess water azeotrope distilled off or it becomes an organic solvent with a boiling point selected the higher than that of water and the water is distilled off.

To the Prevent particle enlargement, agglomeration or aggregation of the resulting nanoparticles may be such surface-modifying Chemicals, as in the state of the art for surface coating of nanoparticles are known to be used. It can be the surface-modifying Reagent on the surface attach the resulting particles.

In at least one solvent, which with the solvent, in which the precipitated product originated is, is miscible, can be at least one dissolved organic Aids for surface modification are located.

In many cases, water is selected as the precipitation medium. The surface-modifying Reagent may be soluble in water to prepare a water-based dispersion. In particular, the agglomeration of particles by addition of organic acids, amines, amides, mono- or polyhydric alcohols or anionic polyelectrolytes, for example polyacrylic acids, which are preferably used in alkaline media or cationic polyelectrolytes, for example polyacrylic acid amides, which are preferably used in a slightly acidic medium , prevented. The stabilizing effect may be electrostatic or steric nature.

It but it is also possible that's for surface coating selected organic reagent such as an organic acid such as oleic acid or stearic acid or such as an amine, such as hexadecylamine or a silicone oil or a Silane then together with the nanoparticles a hydrophobic, with water forms immiscible, separable phase.

The Reagent can therefore be poor even in the dispersion-forming medium water soluble or insoluble be and therefore be dissolved in a water-miscible solvent and simultaneously or preferably after a little time lag in a microreactor the precipitation be added.

The water-miscible solvents can at the same time also the above already described Take over function of solubility reduction.

Frequently it makes sense to have the continuous surface modification with this Reactant reagent is timed defined, so that the solvent in a microreactor downstream of the first microreactor added dispersion is added at a defined distance. So you can define the resulting particles in the first reactor first let it grow and then stop growing by coating.

The Amount of an organic, surface-modifying Reagent can be so tightly selected be that the coating to prevent a coalescence of Although nanoparticles already sufficient, but only a weak surface stabilization the particles take place and therefore still a formation of easily filterable Nanoparticle flakes are made by slight agglomeration and the Nanoparticles are filtered off and washed. For surface coating can for example, polyacrylic acid or Polyvinyl alcohol or polyvinylpyrrolidone or related or For this Purpose suitable, commercial Products are used. In water as a precipitation medium and polyacrylic acid succeeds such as the production of nanoparticulate iron oxide. The filtered and washed nanoparticles can then be reused are absorbed in water and by further addition of, for example polyacrylic acid and glycerol redispersed.

A Hydrophobization of the surfaces which leads to a phase separation, can also be done by a simple treatment with silicone oil.

In a solvent, also in a water-miscible solvent, may be a hydrolyzable organic surface modification agent and after hydrolysis on the surface of the resulting particles attach. In particular, these are hydrolyzable organosilanes. These are primarily alkoxyalkylsilanes and haloalkylsilanes.

Is possible also coating of metallic surfaces, in particular aluminum surfaces, with transparent colored inorganic layers. Such coatings, which are essentially made of hydrolyzable silanes, being on the usual Chromating can be dispensed with, are known. It will be usually alkoxyalkylsilanes, such as trimethylethoxysilane or tetraethoxysilane or hydrolyzable silanes used in at where a nonhydrolyzable radical is a polymerizable end having. In particular for the production of colored, transparent Coatings on aluminum can in extension of the prior art described according to the invention metal oxide Coating solutions produced in which the hydrolyzed silanes in addition to the surfaces of freshly felled, colored connect nanoscale particles as a coating. The freshly felled colored Dispersions thus become deviant in the production of the coating sols used by the prior art instead of water, whereby one to transparent, colored layers arrives.

An application for dispersions of hydrophobicized particles produced by the process according to the invention is the incorporation of the particles into a polymerizable monomer. The monomer may be acrylate or methacrylate and be stirred first with the particle dispersion. By using surfactants, unpolymerized acrylate beads are formed while stirring as a dispersion in water, the acrylate beads then being filled with the precipitated hydrophobicized particles and then polymerized with stirring. This results in microspheres of polymer with entrapped nanoparticles. The microspheres can be used for incorporation in plastics or for the simple production of paints, paints, cosmetic, pharmaceutical or used in medical products. If the incorporated precipitated particles are titanium dioxide, iron oxide or zinc oxide, the microspheres can be used, for example, for the preparation of sunscreen preparations.

The felled and coated products be subjected to a physical aftertreatment. This aftertreatment for targeted change of chemical composition, physical structure, morphology or structural homogeneity the one on their surface modified particles succeed in that the dispersion either with the included, continuously precipitated particles or with the already surface-modified Particle is treated at a definable time interval.

The physical aftertreatment may be a thermal treatment, a microwave treatment, a treatment with infrared or ultraviolet rays, or a treatment under high hydrodynamics. The high hydrodynamics can be realized by vigorous stirring, for example in an Ultraturrax stirrer or a pump with stirring function, in an ultrasonic field or under cavitation generated by high-pressure pumping. A strong mixing can also be produced by pressing the dispersion to be treated by means of pumps through nozzles, it also being possible to arrange a plurality of nozzles with widening nozzle diameters in succession. Or the liquid jets thus formed may collide against a baffle plate or, preferably, against each other. It is possible for a reactor accordingly EP 1165224 to use. Particularly preferred is an embodiment in which the liquid jets are formed by means of hard material nozzles, preferably of ceramic, such as sapphire or ruby or of diamond.

The Formation of the colliding rays can also be carried out in such a way that with a metal tube, as for example for medical Spraying usual and available in many dimensions is, such a part is milled away in the middle of the tube, that only one footbridge remains, the two tube halves connects with each other. The opposite ends of the two tube halves are each with the product feeder connected. The advantage of such an embodiment is that by the remaining web alignment of the nozzles no longer is required. The two tube halves can thereby by a kink in the connecting bridge also be aligned at an angle, which deviates from 180 degrees. By the connecting bridge remain also in this case the jet-forming tubes are stacked.

The physical aftertreatment can also be a steam jet milling, wherein the steam is advantageously already overheated in the precipitation reactor Reactant feed, by supplying a hot flushing medium or by microwave heating is generated in the product output.

So This physical aftertreatment can be carried out with constant chemical Composition of the precipitated Particles to a transition in an alternative morphological state, so for example lead to a different, usually more stable form of crystallization.

All in all succeeds, for example, by the immediate subsequent post-treatment the production of very finely divided, nanoscale zinc oxide first precipitated amorphous zinc hydroxide hydrate before emerging from the amorphous zinc hydroxide hydrate a significant proportion of crystalline zinc hydroxide (a process, which proceeds without action at room temperature in a short time) form can, which then only under more difficult conditions could be converted into zinc oxide. This also succeeds when described as co-precipitation above, a mixture with a co-precipitated Product was made.

in the inventive method was achieved that the production of nanoscale particles with desired uniform morphology and particle size in a continuous Procedure is realized. Essential for achieving monomodal Nanoparticles with narrow size distribution is at first a fast mixing of the reactants used. The to precipitation the nanoparticle leading fast mixing can be done in a Y-mixer or a T-mixer or in microreactors, as they are now known in many designs are done in which the reactants are pressed by pressure from hair-thin channels be, with the reactant channels for the different ones Reactants are usually arranged alternately.

Certain Advantages brings an execution, in each case between the Reaktandenkanälen additional channels for the Outlet of unreacted media are arranged. This unresponsive Media can liquids or gases and serve to prevent blockages during operation and to empty the reactor after stoppage and subsequent blockages to prevent.

For an industrial Production according to the present invention in microreactors in principle all versions suitable in which there is no clogging of the narrow channels of the microreactors can come.

Well suited for use in the present process are various microreactors, in particular the microreactors according to the invention, but also those in EP 1165224 described microreactor in which the reaction takes place by the meeting of liquid reactant jets in a gas space, wherein in each case at least two fine liquid jets with jet diameter preferably between 50 .mu.m and 2 mm, more preferably between 100 .mu.m and 500 .mu.m meet in a gas space at high speed, mix and the precipitated reaction products are discharged by means of a gas or a liquid. However, according to the invention, it is also possible to use reactors as they are known in 1 to 5 are shown used.

there Is it possible, that the purge gas only due to pressure drop or higher Temperature by changing the state of aggregation or by increasing the temperature in the Microreactor forms. At least one of the product feeds can over the Boiling point of the solvent be heated so that the solvent after passing through the nozzle because of the local pressure drop then at least partially evaporated and thereby as always forming and again condensable purge gas for disposal stands. It is also possible that the gas itself forms or passes through the chemical reaction targeted addition of appropriate reactants in addition to the reactants. Especially come for that Carbon dioxide or ammonia in question.

It has been found that in the case of a large number of precipitations, in particular if the precipitations are carried out with low-concentration reactant solutions, the supply of purge gas or rinsing liquid can be dispensed with at least temporarily. In reactors with a relatively narrow product discharge channel, however, it is also advantageous in these cases to use a purge gas or a rinsing liquid for rinsing, for cleaning or for emptying. At the in 1 to 5 Accordingly, there is a connection for such an input, for example, perpendicular to the illustrated section plane on the reaction space shown reactors 3 , while the output for the product and the flushing medium, for example, is also vertically below the illustrated section plane.

These Reactors can also be operated so that applied to the product output a negative pressure will and the purge gas for the Reactor by evaporation of the solvent, preferably water, forms. The vaporized solvent may be in a cold trap be condensed. The product can also be in a cold trap together with the solvent obtained frozen and freeze-dried.

The inventive method can also be done like this be that at least two jet-forming nozzles or nozzle tubes adjustable in brackets are stored and the nozzles be adjusted to each other so that the rays at an angle of 180 degrees or a blunt or at a sharp angle, where the nozzles are are located in a largely material distant environment and the resulting Product mist can propagate largely in all three dimensions. This environment can by a housing, for example, a container with a volume of a few milliliters up to several thousand liters be limited. The droplets of the mist forming in the collision then settle due to gravity on the bottom of the container.

Of the Reactor can also be designed so that one for the collision of free rays suitable gas space thereby forms that the resulting mist from dispersion of precipitated particles by gravity removed from the collision space.

Of the Reactor can also be operated so that the operation in one container carried out in the dipped state will, and on a purge gas or a rinsing liquid Completely is waived.

The purge or the rinsing liquid can in Guided cycle become. For circulation of purge gas this is separated from the product in a gas separator. The circulation of a rinse succeeds in that the rinsing liquid with the dispersion containing reaction medium is immiscible and thus forms a separable phase that is recycled. The "rinsing liquid" which is immiscible with the product dispersion can also be static in the air Reaction space remain while the product dispersion settles down or out of the reactor floating up. In any case, by means of a separate phase forming "rinsing liquid" the reaction space, which, realistically, exists only in the dispersed phase, kept small and a backmixing and at the same time the possibility prevents reactor clogging. The rinsing liquid can be silver oil.

The liquid jets are preferably generated in reactors by means of nozzles. For this purpose, pressures between preferably 50-200 bar are generated with pumps, preferably positive displacement pumps. Of course, higher or lower pressures can also be used. However, lower pressures result in lower sales volumes, higher pressures lead to an increase in the mixing speed but also to higher costs for the pump energy. The diameter of the reactor space should preferably be the multiple diameter correspond to the nozzles for supplying the reactant beams. The factor is favorably between 5 and 50, a factor between 10 and 25 is particularly favorable.

In a used in the invention Plant engineering are the pumps that promote the flow of reactants in the Serving microreactor, preferably by means of a pH transmitter or conductivity transmitter regulated at the product output and a controller.

Of the Period until complete Mixing is in such a microreactor, depending on nozzle widths, Pump pressure, reactant viscosity, temperature and other parameters usually below one millisecond and can be reduced to less than 50 microseconds by increasing the pump pressure or Reduction of the nozzle diameter shortened if an extremely high nucleation rate is this required.

By the use of a cool flushing medium, especially when using a liquid, preferably one with the dispersion immiscible, flushing medium, the resulting product chilled be and simultaneously, especially when using a gaseous flushing medium the transport from the microreactor into and through a heat exchanger be significantly accelerated, so that a very effective cooling is achieved even if the internal geometric dimensions of the heat exchanger To prevent constipation are much larger than those in the microreaction technology introduced according to the prior art, but clog-prone heat exchanger.

By the use of a hot flushing medium a chemical or physical conversion can be effected. Due to the energy content of the hot flushing medium but also the precipitation medium be evaporated. If the hot flushing medium is a gas, you can get to dried powders. The output of the microreactor behave then like a spray-drying nozzle. Provided the hot flushing medium a liquid is, receives after evaporation of the precipitation medium a dispersion in the rinsing medium.

In the beginning and in the final phase of the operation of the microreactor It can happen that a solvent jet enters the opposite nozzle and there a precipitate "behind the nozzle "causes, as long as For example, the system is not vented on a reactor side yet. For this reason, the reactor can have an additional Bore be equipped with a blocker that temporarily with a Störstift protrudes into the collision point to avoid possible blocking. This Störstift is for example pneumatically or preferably by means of an electromagnet emotional. The solenoid is preferred to a pressure gauge connected to a pressure gauge with switching contact and from this controlled. Only when crossing an adjustable minimum pressure in both supply lines for the reactants becomes the sturgeon pin removed from the collision point. The sturgeon pin can move freely over the orifices stand or optionally be constructed so that it the nozzle openings seals.

Further Examples of the application of the method according to the invention are the preparation of particles by precipitation or co-precipitation the subsequent substances, or the coating of dispersed or freshly felled Particles by subsequent precipitation or co-precipitation with at least one of the following substances, namely aluminum hydroxide, Alumina, aluminum silicate, aluminum titanate, antimony oxides, Barium ferrite, barium stannate, barium sulfate, barium titanate and others Titanates, lead zirconate, borates, calcium carbonate and other carbonates, Calcium hydroxide phosphate, calcium fluoride, calcium stearate, cerium oxide, nano-glass, iron oxides, nano-enamel, Ferrofluids, indium oxide, lanthanum oxide, lithium titanate, magnesium oxide, Magnetofluids, manganese oxide, sodium aluminosilicate and other silicates, Nickel hydroxide, nickel ferrite, nickel oxides, nickel sulfide, nickel titanate, Silver halides and other halides, silica, strontium carbonate, Strontium sulfate, titanium dioxide, yttrium aluminum garnet, yttrium vanadate, Zinc oxide, zinc sulfide, zinc terephthalate and other terephthalates, tin oxide, zirconium phosphate and other phosphates, zirconia, as well as mixed metal oxides with the aforementioned substances, partly as doping, as well as other perovskites, Semiconductors, superconductors and other electroceramic materials. Typical examples are also the production of antimony tin oxide or antimony zinc oxide or indium tin oxide or indium zinc oxide.

By Coating of silica particles with iron oxide or titanium dioxide For example, you can get particles with special properties for the Cosmetics.

It can Particles coated with magnetic iron oxides or magnetic or superparamagnetic particles to particles with special optical Properties are coated and processed by Applying electric fields arranged in one direction or be arranged to specific geometric patterns.

Of the chemical process and the stoichiometry of respective precipitation can do it after the for the respective precipitation in a stirred reactor known prior art done.

Titanium dioxide and thus may be precipitated as, for example, a dispersion or fresh one at whose precipitation immediately following, slightly precipitated precipitation in time of at least one metal phosphate for the production of anticorrosive White pigments be coated. The precipitation The phosphates as a single step are carried out according to the in The literature describes procedures for the precipitation of phosphates. The metal component of the phosphates are, for example, cerium, zinc, Aluminum or manganese in question. Alternatively or additionally in a further time-delayed precipitation another inorganic Layer, for example of aluminum hydroxide or aluminum oxide be applied. Freshly felled Zinc oxide or zinc hydroxide can thus be coated with zinc sulfide. Zinc sulfide or zinc sulfide coated metal oxide, also zinc oxide can become electrically conductive by treatment with copper sulphate solution.

Conductive coatings receives one by the temporally slightly offset incidence of mixed oxides of tin or zinc with indium oxide or antimony oxide or alumina according to the prior art from the corresponding acids and Alkalis. By staggered precipitation of metal titanates on Titanium dioxide is obtained, for example, to catalysts for the polymerisation. Further Examples are nano-cosmetics and nano-pharmaceuticals by solvent-nonsolvent precipitation or by loosening in lye and precipitation with acid. However, this production can also be carried out in this way that simultaneously to the precipitation or, preferably slightly offset in time in a second reactor, a co-precipitation of nanoscale, inorganic product. In particular, the solubility of poorly soluble Pharmaceuticals can be greatly improved if the precipitated inorganic Product depending on the requirement, a high solubility in blood or a high solubility in acid, also as carbonate or bicarbonate with elimination of carbon dioxide, or gastric fluid or a high solubility in lye, or intestinal fluid has. The precipitation can also be done in a mixture of water with solvent, so that also inorganic products, or salts to precipitate, the water-soluble and biocompatible are.

Further Examples are the production of organic explosives by reactive precipitation of benzanate or other explosives. Other examples are the production of organic pigments by reactive precipitation in microreactors according to the invention by azo coupling or by solvent Nonsolventfällung of in sulfuric acid dissolved Pigments using water as Nonsolvent. It can be advantageous be when the precipitation as co-precipitation is carried out with inorganic particles, preferably such that the inorganic particles to at least one of the reactants or over a separate Reaktandeingingang be added as a dispersion or by a precipitation in time immediately before the precipitation the organic particles are formed.

It is part of this invention that the devices described here instead of producing nanoscale products as non-clogging chemical microreactors are used. In this application area these devices are particularly useful when it comes to such Reactions unintentionally to precipitates or incrustations can come. The special advantage arises as well as in the precipitation of nanoscale products from the flushability of the reaction space with a purge gas or a rinsing liquid. there Is it possible, that the purge gas only due to pressure drop or higher temperature due to change the aggregate state or by increasing the temperature in the microreactor forms. It is also possible, that the gas forms by the chemical reaction itself or by specific addition of appropriate reactants in addition to the reactants. In particular comes for carbon dioxide or ammonia in question.

A further execution sees the spray drying of felled Products. As purge gas becomes a hot one Supplied with gas, which due to its amount and temperature sufficient energy contains to evaporate the dispersing medium so that solvent vapor, For example, water vapor, and free particles emerge. In a connected to the reactor arrangement, the spray drying line According to the prior art, then fall solid particles at.

A further embodiment provides for the production of dispersions or emulsions in which the colliding liquids are immiscible or only to a limited extent miscible with each other and at least one dissolved substance is present in at least one of the liquid jets. The process control is designed so that the liquid containing the solute evaporates after collision in the reactor or in the subsequent stretch and the previously dissolved substance then dissolved in the remaining non-solvent medium dispersed or not dissolved emulsified in the remaining liquid remains. The evaporation takes place in that at least one of the two liquids is heated prior to entering the reactor, for example by means of an externally tempered, spiral feed line, wherein the temperature may also be above the boiling point of the liquid. Or the gas supplied is heated before it enters the reactor. Alternatively or additionally, a negative pressure can be applied to the product outlet. On In this way, aqueous dispersions of water-insoluble substances can be prepared. Surface-modifying reagents may be dissolved in at least one of the at least two liquid jets or may be added in a time-delayed manner.

Explanation to the drawings:

1 - 5 show exemplary embodiments of the microreactors used in the inventive arrangement. Via the supply lines ( 1 ) the liquids containing reactants pass through the nozzles ( 2 ) in the non-clogging room 3 of the reactor housing 4 , The space ( 3 ) has at least one outlet for the product removal, and optionally and preferably a supply for a purge gas or a rinsing liquid. A particular advantage of the arrangements according to the invention is that the nozzles ( 2 ) consist of hard material. For this purpose, hard metals or, for example, carbides, nitrides or other hard materials can be used as nozzles. Particularly suitable are on the market in a wide variety of available nozzles of alumina, as sapphires or rubies. Also well suited, but more expensive, are diamond nozzles.

5 shows a microreactor with two interconnected access lines ( 1a ) and ( 1b ), in which the reactants are mixed by two nested tubes on a baffle plate, wherein the inner supply advantageously can protrude a little further in the reactor interior, whereby in the gas or liquid flushed reactor interior a post-reaction in the supply lines after stopped Reaktandenzufuhr can be safely avoided.

Claims (27)

Method and apparatus for continuous precipitation of nanoscale products, characterized in that primary particles by precipitation by means of chemical reaction according to the prior art, for example from acids, Lyes or salts or by a solvent nonsolvent precipitation by means of fast mixing fluid jets in a continuous reactor, but preferably a blockage-free Microreactor can be generated and optionally these particles within a definable, short temporal and, apparatively speaking, short spatial Distance, preferably in a microreactor through at least one chemical precipitation reaction or co-precipitation reaction on the surface be coated or modified. Method and apparatus according to the preceding claims, characterized in that the resulting nanoscale particles on its surface be modified in that additionally at least one solvent jet at least one surface-modifying Reagent is added or the blended solvent for precipitation at least one surface-modifying Reagent immediately after mixing the solvent jets is added, wherein the surface-modifying reagent also in a solvent can be located and against the same or your own spatially subordinate Impact device is directed or via a nozzle which merges or already admixed reagents and this surface modification from several successive operations with the same reagent or different reagents and at least one the reactants are heated or cooled can. Method and apparatus according to the preceding claims, characterized in that the surface-modifying reagent at least one surfactant, an anionic, cationic or nonionic Surfactant, a hydrolyzable, reactive alkoxyalkylsilane or a organic acid, an alcohol or a polymeric acid or at least one organic or inorganic compound that can be on the surface the felled Coupled particles. Method and apparatus according to the preceding claims, characterized in that serves as a medium for the precipitation of water and the for surface coating selected organic reagent along with the nanoparticles one with water immiscible, separable phase forms and the organic reagent in a water-miscible solvent solved at the same time as the precipitation or added a short distance after the precipitation. Method and apparatus according to the preceding claims, characterized in that serves as a medium for the precipitation of water and the amount one for surface coating selected organic, surface-modifying Reagent so selected is that the coating to prevent the growing together of Nanoparticles in the sense of Ostwaldt maturation is sufficient, but one more Formation of easily filterable nanoparticle flakes by light Agglomeration takes place and the nanoparticles filtered off, washed and redispersible by addition of further surface modifier become. Method and device according to the preceding claims, characterized in that the particles formed by chemical precipitation and optionally by an additional surface coating by a treatment with Nonsolvent to be made to the solvent. Method and apparatus according to the preceding claims, characterized in that at least two liquids by at least two nozzles be injected into a collision space, these being Nozzles preferred around hard material nozzles in particular of hard metals or metal oxides, preferably from Alumina, sapphire or ruby or carbides or nitrides or can be made of diamond and the collision space and the exit of the collision space are designed so that they fall off Particles can not be blocked and that leading to the precipitation reaction a mixing reaction of at least two solvent jets, preferably Water, in which the reactants dissolved in, colloidally dissolved, emulsified or dispersed state, and the solvent jets at an obtuse angle or at an angle of 180 degrees or meet at a sharp or obtuse angle or hit against a baffle or two innesteckenden nozzle tubes Concentric against a baffle and hit through the mixture of solvent jets rainfall form as a result of a chemical reaction to a non-soluble precipitate or as a result of a reduced solubility of the resulting Solvent mixture for in the individual jets contained, dissolved ingredients and the supplied reactants optionally cooled or can be heated. Device according to the preceding claims, characterized in that that for feeding the microreactor with the desired precipitation required reagents at least two high-pressure membrane pumps be used in the pressure range between 5 bar and 5000 bar and for damping the resulting pressure pulsations between each high-pressure membrane pump and the associated Microreactor side a pulsation damper is used. Device according to the preceding claims, characterized in that the charging of the microreactor with those required for the desired precipitation Reagents happen by means of high-pressure diaphragm pumps and the pumps, the the promotion the reactant streams serve in the microreactor, by means of a sensor at the product outlet, optionally over conductivity or pH can be controlled. Device according to the preceding claims, characterized in that the colloidal dispersion formed in the microreactor the precipitation products as a gas-liquid mist before or after at least one possible coating by means of a Gas stream discharged from the reactor chamber and through a heat exchanger for fast dissipation of exothermic energy is performed. Method and apparatus according to the preceding claims, characterized in that the resulting in the collision space during the precipitation Dispersion by subsequent reaction medium or resulting Dispersion from the filled collision space repressed is or optionally by means of a supplied gas or a through Reaction or pressure drop or increase in temperature resulting gas or by means of a liquid or a liquid immiscible with the reaction medium permanently removed from the collision space or the collision space with gas or a liquid immiscible with the reaction medium filled is and the resulting dispersion by gravity from the collision space Will get removed. Method and apparatus according to the preceding claims, characterized in that the precipitation medium resulting from the precipitation Dispersion by supplied, heated gas is evaporated, the energy of the gas supplied sufficient by amount and temperature to a complete evaporation and by the gas and the resulting vapor from the collision space repressed is and the subsequent process route according to a spray-drying plant is designed and the process in its entirety as a precipitation process with integrated spray drying represents. Method and device according to the preceding claims, characterized in that the parameters of the inner geometric dimensions of the collision space are usually between about 0.5 mm and 50 mm, more preferably between 1 and 10 mm, but may also be larger or smaller and in the Usually a multiple of the nozzle diameter, which advantageously between 0.05 mm and 2 mm, particularly advantageously between 0.1 and 0.3 mm, but may also have a smaller or larger diameter and thereby the nozzles may have different diameters and the Collision space has a product outlet and optionally an input for a purge gas or a rinsing liquid or that a microreactor according to the EP 1165224 is used and the nozzles can also have a different diameter. Method and apparatus according to the preceding claims, characterized in that in at least one of the liquid jets nanoscale or microscale, metallic or inorganic particles or platelets are on their surface with the nanoscale precipitation products be coated. Method and apparatus according to the preceding claims, characterized in that the optional surface-modifying Reagent coated, dispersed in a solvent Particles within a definable short time interval one subjected to physical aftertreatment, wherein the After-treatment immediate in time, ie in the millisecond range, in seconds or minutes, at the precipitation or to the coating of the surface the felled Connect particles can and the physical aftertreatment at least one thermal Treatment, a microwave treatment, a treatment with infrared or ultraviolet rays, but preferably an ultrasonic treatment or may be a treatment with strong mixing, the strong mixing by commercial dispersing, preferred but is generated by striking rays thereby and that for this purpose the dispersion to be treated is pressed by means of pumps through nozzles and the liquid jets thus formed in a relaxed atmosphere collide against a baffle or against each other, or through a second nozzle with larger nozzle width is pressed. Method and apparatus according to the preceding claims, characterized in that the physical aftertreatment in Constant chemical composition of the precipitated particles to a transition in an alternative morphological state, so for example a other, more stable crystallization form leads. Device according to the preceding claims, characterized in that, for the conversion of the substance, the precipitated products which have left the reactor are converted spirally wound high-pressure tubes as feed lines for the microreactor be used and the products during a cycle of the felled and possibly coated products by immersing the coiled high-pressure pipes in at least a hot one Dipping bath to be heated. Device according to the preceding claims, characterized in that the charging of the microreactor with those required for the desired precipitation Reagents are done by means of high pressure membrane pumps and the subsequent After-treatment for surface coating and for conversion by recirculation of the leaked from the reactor precipitated products is carried out under adaptation to the process parameters required for this purpose. A method and apparatus according to the preceding claims, characterized in that by precipitation from sulfuric acid and optionally or instead of sulfuric acid at least one metal sulfate ₁ with metal ₂ hydroxide or preferably metal ₂ bicarbonate companion salt-free nanoscale metal ₂ sulfate or a nanoscale mixed metal product ₂ sulfate and metal ₁ oxide or metal ₁ hydroxide is formed and so, for example, barium sulfate, magnesium sulfate or calcium sulfate alone or together, also formed as a coating with, for example, zinc oxide, antimony oxide or iron oxide. Method and apparatus according to the preceding claims, characterized in that by precipitation from phosphoric acid with at least one metal hydroxide or at least one metal hydrogencarbonate at least one nanoscale metal phosphate or hydrogen phosphate free of salts or hydroxy phosphate is formed and so, for example, calcium hydroxyapatite or zinc magnesium phosphate or other phosphates. Method and apparatus according to the preceding claims, characterized in that by precipitation from titanic acid or Titanyl sulfate with at least one metal hydroxide or preferably at least a metal hydrogencarbonate salt-free nano-scale titanium dioxide with at least one metal oxide or metal hydroxide is formed. Method and apparatus according to the preceding claims, characterized in that for the precipitation of additional Metal sulfate or phosphate on the mixture of metal oxide or hydroxide particles the metal sulfate in addition sulfuric acid or phosphoric acid or subsequently timely defined added at a short distance to the particle dispersion will or first a barium sulphate precipitation and timed within a short distance a co-precipitation of Barium sulfate takes place with metal oxide. Method and device according to the preceding claims, characterized in that particles are prepared by precipitation or co-precipitation of the subsequent substances, or coating of dispersed or freshly precipitated particles by subsequent precipitation or co-precipitation with at least one of the following substances are performed namely particles or dispersions of aluminum hydroxide, aluminum oxide, aluminum silicate, aluminum titanate, antimony oxides, barium ferrite, barium stannate, barium sulfate, barium titanate, lead zirconate, borate, calcium carbonate and other carbonates, calcium hydroxide phosphate, calcium fluoride, calcium stearate, cerium oxide, nano-glass, iron oxides, nano-enamel, Ferrofluids, lanthanum oxide, lithium titanate, magnesia, magnetofluids, manganese oxide, sodium aluminosilicate, nickel hydroxide, nickel ferrite, nickel oxides, nickel sulfide, nickel titanate and other titanates, silver halides, and others ren halides, silica, strontium carbonate, strontium sulfate, titanium dioxide, yttrium aluminum garnet, yttrium vanadate, zinc oxide, zinc sulfide, zinc terephthalate and other terephthalates, tin oxide, zirconium phosphate and other phosphates, zirconium oxide, and mixed metal oxides with the aforementioned substances, also as doping, as well as others Catalysts, perovskites, semiconductors, superconductors and other electroceramic materials, as well as nano-cosmetics and nano-pharmaceuticals or organic dispersions for coatings, as well as organic pigments are produced. Apparatus for the continuous production of nanoscale products in a microreactor, characterized by that electrically conductive particles or electrically conductive Layers or body are made of nanoparticles or microparticles with Tin oxide or zinc oxide together with indium oxide, alumina, manganese oxide or antimony oxide by precipitation be coated. Apparatus for the continuous production of nanoscale products in a microreactor, characterized by that the particles are filling of plastics and paints or for the production of solids for ceramic Products for the manufacture of conductive bodies or layers, scratch-resistant bodies or layers, for the production of electroceramic products, for Production of catalysts or explosives can be used. Method and apparatus according to the preceding claims, characterized in that the physical aftertreatment of precipitated particles of a hydroxide form or a hydrated hydroxide form a transition to an oxide form to a less hydrated oxide form or leads to a hydrated oxide form. Apparatus for the continuous production of nanoscale products in a microreactor, characterized by that the device described as a non-clogging chemical Microreactor, instead of precipitation of nanoparticles used in chemical conversions which it is not intended to precipitate or incrustations can come.