DE102005048201A1 - Method and device, for continuous precipitation of nanoscalic product, comprises preparing primary particles by chemical reaction precipitating and optionally modifying the particle surface by chemical precipitating or co-precipitating - Google Patents

Abstract

Method and device, for continuous precipitation of nanoscalic product, comprises preparing primary particles by precipitating via conventional chemical reaction or by solvent-nonsolvent precipitation agent; and optionally coating/modifying the particle surface by chemical precipitating or co-precipitating reaction within a definable, short time, apparatus and short spatial interval. Method and device, for continuous precipitation of nanoscalic product, comprises preparing primary particles by precipitating via conventional chemical reaction (e.g. from acids, caustic solutions or salts) or by solvent-nonsolvent precipitation agent by quick mixing fluid jet in a continuous reactor; and optionally coating/modifying the particle surface by chemical precipitating or co-precipitating reaction within a definable, short time, apparatus and short spatial interval.

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 Mischmetalloxiden, 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, the inhomogeneous precipitate causes, 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 with ceramic particles in water is significantly smaller 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 der 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 value Surround yourself while the precipitation Part of the resulting particles is located at the isolelectric point, where the electrostatic repulsion 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 aqueous precipitation medium with hydrophilic surface modifiers be coated in such a way that by steric stabilization despite the presence of companion salts 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 hydrophobed and in immediate time 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, preferably a short-chain alcohol 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 may be subsequently added as a third component in a microreactor in the mixing zone of the reactants or spatially subsequently and thus during operation.

When Example is the precipitation of alkali silicates with acids. According to the invention, this precipitation is by continuous feeding of the reactants for mixing in one clog-free microreactor carried out while the acid a share a water-miscible solvent, preferably alcohol added. 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 or a metal halide 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 contents of each individual channel then react 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, which leads to unreliable and uncontrollable disadvantages in the stoichiometry of the reaction in the individual channels, too if the total stoichiometry, ie the sum of the reactant streams of the "multi - channel" system is complied with.

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 without great pressure loss, in the process according to the invention pressures of> 10 bar, particularly preferably> 30 bar are established the low nozzle resistance shows that the total flow through a single nozzle comparable to the flow of a variety of channels in a "multi-channel" -. System is. Since these nozzles are manufactured with high precision and reproducibility both from the nozzle length as well as from their diameter, several such "single-channel" reactors can additionally be operated in parallel, without it being the case with the "multi-channel" systems Stoichiometric uncertainties and errors come.

Of the parallel construction of microreactors according to the invention can be so be designed that several such "single-channel" reactors on one common base plate are located. The nozzles can be fixed or removable be fixed and can be mounted in pairs or individually. Removable nozzles can be elastomeric or metallic or sealed by screw thread. The nozzles can also be pressed or glued into the holder. The nozzles can do that on support plates be mounted that when assembling two plates each two nozzles in pairs face.

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 purposeful adjustment of a desired pH value in the 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 Mischmetalloxiden, 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.

Well the method is also suitable for the production of perovskite structures, like titanates. For example, from the reaction of a mixture of barium chloride solution and Titanium tetrachloride solution with lye leaves yourself nanoparticulate Precipitate barium titanate. Replacing the acidic barium salt with an acidic salt of another Metal, such as antimony, lithium, zinc, bismuth or Strontium are also the respective titanates.

These Procedure of simultaneous precipitation several oxides can be, for example, for the production of nano - glass or nano - use email, 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.

In one embodiment of the plant technology used in the invention, the pumps that promote the flow of reactants in the Serving microreactor, preferably regulated by means of a conductivity or pH sensor at the product output and a controller. However, the dosage can also be regulated by means of differential dosing scales or flowmeters. Very particularly preferred is the pump control via the electrical output of pressure gauges that measure the back pressure of the liquids in front of the nozzles.

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 of the pH value and mixed for this purpose at least one reactant. For electrostatic stabilization of the resulting particles is It is usually advantageous if the pH value in the resulting dispersion at least 2 whole pH steps from Isoelectric point is located away.

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.

The rinsing medium can at the same time also contain at least one reactant or itself be a reactant, in particular if the reactant is a gas. In the precipitation of iron (II) hydroxide from an acidic iron salt and brine, for example, the greenish iron (II) hydroxide is converted directly into the yellow goethite (Fe ³⁺ ), if the flushing medium contains oxygen or consists of oxygen.

From Meaning of the production of some precipitated products, in particular of oxides, is also the possibility of heating the supplied Reactants. According to the devices described here to the feeder the reactants used pumps that allow high operating pressures. Preference is given to pressures between 10 and 400 bar. Due to the generated by the pumps pressures in the pipelines of the supplied Reactants, can These are so in the pipelines far above the boiling point of their solvent be heated at room temperature without the solvent goes into the vapor state. The temperature of the solvent for the Reactants can be increased to such an extent that the vapor pressure within this pressure spectrum increases. For dissolved in water reactants Thus, temperatures of several hundred degrees Celsius are possible. For water as a solvent this may mean that the reaction is in the supercritical range (above 221 bar and above 374 ° C) carried out becomes. In the supercritical Range increases the reaction rate significantly. simultaneously has supercritical water but a low dielectric constant, so that the Hamakerkonstante becomes larger as in subcritical water. The production of iron oxides succeeds for example, directly from 0.5 molar aqueous dissolved iron (III) salt by reaction with equimolar Amount of caustic solution at temperatures around 150 ° C and overpressure from 5 bar.

According to the invention, this is in front of the reactor, preferably between a filter and the reactor, a heated tube. The heating takes place, for example, by immersed or double-walled spiral coil or an electric heater located around the respective pressure pipe. In order for the reaction occurring at the collision of the reactants to proceed at the desired high temperature, a pressure-maintaining valve is located in the product outlet. In addition, a heat exchanger for cooling the superheated solvent vapor is located in the product outlet. The pressure holding valve can be adjusted in proportion to the temperature of the solvent so that a portion of the solvent evaporates in the reactor and thus serves as a purge gas for the microreactor. In this case, the heat exchanger is arranged after the pressure-holding valve.

When Pressure-holding valve may also serve a nozzle, preferably a hard material nozzle, whose diameter is chosen is that builds up a back pressure due to the boundary conditions. The passage of the reaction product through the nozzle can additionally a effect physical conversion. For example, a Transformation of morphological structure from amorphous to crystalline Condition or conversion of metal hydroxides to oxide hydroxides or oxides.

On this way succeeds in precipitation reactions to arrive at alternative morphologies of the precipitated products. If you fall for example, acidic aluminum salt with alkali or sodium aluminate with acid, so receives under normal pressure conditions, depending on the pH at which the precipitation is carried out, predominantly bayerite or boehmite. If you lead the precipitation against it at overpressure and elevated temperature through, you get with increasing temperature increasingly diaspor. Effective are already temperatures of 160-180 ° C at a corresponding Vapor pressure of 10-20 bar, which is maintained by means of pressure-holding valve. The thus obtained Diaspore can be used for easy conversion to alpha alumina. The pressure holding valve may also be arranged after the heat exchanger. In this case, the formation of steam in the reactor is less controllable.

In the precipitation of iron (II) hydroxide from an acidic iron (II) salt and alkali, for example, the greenish iron (II) hydroxide is directly converted into the red hematite (Fe ³⁺ ), if the flushing medium contains oxygen or out Oxygen exists and under the aforementioned high temperatures (150-180 ° C) under elevated pressure (15 - 20 bar) is worked.

Should the spinel-structure iron (II) iron (III) mixed oxide by precipitation from an acidic iron (II), - (III) Salt mixture like lye be done, the flushing happens without oxygen, as an oxidation of the iron (II) salt avoided shall be.

Especially if with heated reactant solutions is worked or if the precipitation reaction exothermic and worked at the same time with high reactant concentrations often produces highly viscous or pasty dispersions. In this Case can be cheap be when the jet-forming nozzles are in separate reactor components and the reactor components so shifted against each other and fixed can be that the rays collide with each other. Especially if no subsequent surface modification carried out it can be beneficial to prevent constipation, if the collision does not take place within a reactor, but the collision point outside of material walls so that they are not stuck by spraying product can.

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

Around according to the inventive method one by electrostatic forces To produce stable dispersion in water, the precipitation is so perform, that after the precipitation sets a pH, the one big Distance to the isoelectric point of the precipitated particles, namely at least two pH steps, that the particles due to the resulting electrostatic stabilization do not coagulate and that then a surface modification by steric acting reagents takes place and only after steric stabilization with a surface modifier the pH required for further processing is set.

At least one reagent is metered in which forms a bond with the existing particle surface by chemical or physical reaction and, if appropriate, an additional surface coating with precipitated solids. This surface treatment can be carried out several times in succession with the same or different reactants.

in this connection can the precipitation products for surface modification be implemented as a dispersion with at least one suitable reactant, the on the surface binds the precipitation products or the precipitation products in short time interval with at least two suitable with each other reacting reactants, resulting in another precipitation and a coating of the original precipitates leads.

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.

at After steric stabilization by surface modification, macromolecules are adsorbed on the surface. The surface layers must be there far more extensive than the Van der Waals forces. Good polymers are suitable 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, an organic acid as a surface modifier is used. By the staggered addition of the acid attacks these are not in 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.

An illustrative example of the production of hydrophobic particles is the procedure for the surface modification of precipitated particles by means of the poorly water-soluble carboxylic acids. Simple carboxylic acids with carbon chains between C ₅ -C ₁₈ or even longer are only very slightly soluble in water, so that the surface modification with these acids represents a difficulty in dispensing with organic solvents. This difficulty has been solved by using, instead of the C ₅ -C ₁₈ carboxylic acids, their alkali metal salts, in particular sodium salts, which are water-soluble in hot water. (The known as greasy soaps (potassium salts) or core soaps (sodium soaps) salts are in water as quasi-dissolved colloidal micelles together, but are not really solved in cold water) Instead of simple carboxylic acids can Mehrfachcarbonsäuren, branched or functionalized carboxylic acids or carboxylic acids be used with multiple bonds, such as oleic acid.

Provided the carboxylic acid with the precipitation reaction serving alkaline reactant no insoluble compound, can this is preferably used as a common, hot reaction solution become.

So at the precipitation of metal oxides or hydroxides by means of acidic salts and lye. If the alkali component is heated together with, for example, 5 g / l Sodium salt of stearic acid on over 80 ° C you get a clear solution. After reaction with the acidic reaction solution in the microreactor to obtain filterable, hydrophobic sol.

This is easy to transfer into various organic media and so for example as a filler for different Applications serve as they are for hydrophobic silica is considered and used as prior art become.

Since the alkali metal salts of the carboxylic acid used in the acidification with strong acid form the corresponding carboxylic acids, which show overall poorer dissolution properties than the salts in water, the coated Pro they were even more hydrophobic.

In In a modification, the addition of the hot-dissolved surface modifier takes place only after a precipitation reaction. Instead of in hot Water or alternatively dissolved in hot alcohol alkali metal salts the carboxylic acids can instead also the carboxylic acids itself, solved in alcohol, to be used. To solve the short-chain carboxylic acids must the alcohol can not be heated. For long-chain carboxylic acids, such as stearic acid however, heating the alcohol is required.

The methods of surface modification with bad methods described above water-soluble carboxylic acids can also independent from a precipitation carried out become.

It but is usually advantageous, as described above Perform methods in a continuous reactor or microreactor.

Instead of The above-described carboxylic acids may be industrially distributed Products containing the specified carboxylic acids or contain their alkali salts to a significant extent and a similar solution behavior demonstrate. Often these are industrially available Products around liquids or pasty Products. In place of the above-described solution of the salts of the carboxylic acid in hot water then usually a mixture of single phase already occurs in the Cold.

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 generally known to be used.

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 becomes water as a precipitation medium selected. The surface-modifying reagent can thereby produce a water-based dispersion in water soluble be. In particular, the agglomeration of particles by addition of organic acids, Amines, amides, monohydric or polyhydric alcohols or anionic Polyelectrolytes, for example polyacrylic acids, preferably in alkaline Media or cationic polyelectrolytes, for example polyacrylic acid amides, which are preferably used in a slightly acidic environment prevented. The stabilizing effect can be electrostatic or steric Be 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. A set of commercial Surfactants which form colloidal solutions with water are suitable for this purpose. These solutions Although they are stable to the extent that they usually no room temperature Phase separation, but their colloidal character is at the cloudiness the solutions easy to recognize. Store together with dispersed particles These surfactants are on the surface of the particles and are therefore also often as hydrophobizing surface modifiers to use. These surfactants can either along with a watery one dissolved Reaction component in the precipitation reaction fed separately or dissolved in water immediately after precipitation or in a water-miscible solvent be added.

The Reagent can also be poor in the dispersion-forming medium soluble or insoluble be and therefore be dissolved in a water-miscible solvent and simultaneously with the precipitation in an additional Beam into the point of collision of the reactants or prefer something time-delayed added in a further microreactor after precipitation become.

So For example, a freshly precipitated aqueous / alcoholic zirconia dispersion or a finished (acid-stabilized) aqueous zirconia sol an alcohol, preferably methanol dilute to the extent that added alkoxysilane in the solvent mixture the dispersion dissolves. To Hydrolysis of the silane and the subsequent coating of the dispersed Particles can be separated by evaporation of methanol aqueous Phase, which (if the dispersion was freshly precipitated) contains accompanying salts, separate. The coated hydrohobic particles can used as organic dispersion or dried and as filler be used.

It but it is also possible that's for surface coating selected organic reagent as aqueous dissolved Salt to the basic watery dissolved Reaction component is added or simultaneously with the precipitation in an additional Beam into the point of collision of the reactants or prefer something time-delayed added in a further microreactor after precipitation becomes.

One Aspect of the present invention is the surface modification of precipitated particles according to the invention by means of hydrolysis more volatile Alkyl metal halides, especially of alkyl silyl halides.

in this connection may otherwise in the microreactor according to the invention as flushing medium Serving gas stream at the same time as a transport medium for the volatile Alkyl metal halides, especially trichloromethylsilane, dichlorodimethylsilane and chlorotrimethylsilane.

Therefore the gas stream consists of an inert purge and carrier gas, such as nitrogen, this being heated by a heated prior to entry into the reactor Alkyl metal halide is passed. As flushing and carrier gas but can also be a preferably water-miscible solvent serve, which is gaseous by heating. Once in the gas stream contained alkyl metal halide with the mist of the aqueous precipitate comes in contact, the alkyl metal halide hydrolyzed with cleavage the halogen group and their replacement by a hydroxide group. there A reactive connection to the surface of the surface is quickly achieved aqueous Precipitates. This is how the aqueous precipitation products become hydrophobic and on further growth in size prevented. An example is the use of trimethylchlorosilane, Dimethyldichlorosilane or methyltrichlorosilane.

One Another aspect of the present invention is the surface modification precipitated particles according to the invention by hydrolysis of pure or water-miscible solvents dissolved alkyl metal halides, in particular alkyl silyl halides and other silyl halides. In this case, in the microreactor according to the invention at least two reactant beams at a collision point to one precipitation reaction brought. additionally becomes at least one more liquid jet in the collision point or temporally and spatially slightly offset as a liquid jet injected into the mist of reaction product, said liquid jet the readily hydrolyzable silyl halides, pure or dissolved in one water-miscible solvent contains.

When precipitates come here a variety of products in question, as for example otherwise according to the prior art by subsequent Treat with hydrolyzable silanes. Especially also succeeds in the production of hydrophobized, precipitated silica on this way. For example, a 10% sodium silicate solution with 80% of the equinormal Amount of sulfuric acid be implemented continuously while simultaneously or in time slightly displaces the remaining 20% of the equatorial amount as gaseous or liquid hydrolyzing halosilane is added. The respective proportions sulfuric acid and Halogensilane can so changed too that together are about 100% of the stoichiometrically required Total amount is used. It is advantageous if the stoichiometric Boundary conditions selected be that no free hydrochloric acid arises. The resulting hydrophobic coated precipitate forms in the precipitation medium a separating phase which is filtered off and washed can. The washed product can be dried and ground. To preserve the monodispersity But it is often cheaper to the still moist washed filtrate a water miscible high-boiling solvent to give and distill the remaining water left. The im solvent Monodispers present particles can then easily into organic Media such as paints, plastics, elastomers and others are transferred or incorporated.

From special economic importance is that way a whole range of hydroxides, oxides, mixed oxides, silicates, and other precipitation products alone or as a coating on other supports nanodispersed in an organic medium can be obtained which can then be easily processed.

One Another example is the coating of nanoscale inorganic or Organic products that are preferred in a non-clogging Microreactor like were or as purchasable Dispersion can be used with a biodegradable plastic. Especially come for it Plastics such as polylactides or their co - glycolides in question. These Plastics can in a water-miscible polar solvent such as dimethylacetamide, Dimethylacetamide or N-methylpyrrolidone solved and be precipitated with water or alcohol. Such as core-shell-coated products can as biodegradable products, for example, for environmentally sound, technical consumables or for medical pharmaceutical Products for In vivo applications for the transport of pharmaceutical agents be used. It can as core at least magnetic particles are used.

One Another example is the hydrophobing of magnesium hydroxide. For this purpose, magnesium chloride is used as aqueous solution with a concentration of 0.1-3 mol continuously reacted with an alkali to magnesium hydroxide, while simultaneously or temporally slightly displaced halosilanes, in particular Trichloromethylsilane gaseous or liquid at the same time or added at a staggered time. At the stoichiometry For the neutralization of the resulting hydrochloric acid, the amount of alkali is preferred adjusted to a pH value of approx. 12.

One Another example is the precipitation a hydrophobic mixed product of zinc oxide and zinc silicate. This can be made from an acidic zinc salt by reaction with different Levels of alkali and sodium silicate and additional hydrophobing by means a chlorosilane are shown.

The hydrophobic precipitates can be washed and in organic media or for filling plastics, paints, Adhesives and elastomers can be used.

there but it is also possible that instead of the in situ precipitation product finished particle dispersions are used. These particles can also be platelets, and lead through the coating to products, as in different Modifications as effect pigments, for example due to interference phenomena be offered on the market.

In Another application will be organic pigments that only in sulfuric acid let solve, 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 used by chemical reaction instead of water become.

In another application in the plastic or latex polymerization instead of the aqueous solutions Nanoparticle dispersions, preferably fresh or simultaneously precipitated, instead be used by water. The surface modification of the inorganic Particulate surfactants can equally as surfactants for serve the latex stabilization. Provided the nanoparticles are salt-free like were, the latices are more stable against refraction. Conversely, arrives in the presence of accompanying salts, by refraction of the latices also to nanoparticles filled Plastics, wherein the refraction according to the prior art for plastics or latex emulsions.

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.

Vice versa is it possible, for example, first sulfuric acid with an excess amount Barium hydroxide to mix and add delayed addition of metal sulfate, which initially Barium sulfate particles are formed, which are then treated with metal oxide barium sulfate be coated.

replaces one part of the zinc sulfate by antimony sulfate, one arrives so too 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, the zinc oxide being used as a transparent ultraviolet light filter can. 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.

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.

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.

Instead of of barium hydroxide Other Hxdroxide 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.

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.

It can also mixed precipitation products in variable composition become. For example, it is possible to precipitate an aqueous acidic solution Zinc salt with an aqueous solution of caustic soda, sodium silicate and sodium stearate the preparation a nanoscale aggregate for the production of rubber.

you can be a precipitation by reaction of an inorganic, aqueous dissolved zinc salt, such as zinc sulfate with an aqueous Lye, such as caustic soda in a microreactor perform and while the lye as a surface modifier that too watery, at elevated Temperature dissolved Salt of a carboxylic acid, such as sodium stearate or disodium terephthalate. In a related Variant is added in a water-miscible solvent, such as ethanol, dissolved organic acid, such as stearic acid in the same reactor as a third component or in a downstream Reactor too. Depending on the temperature of the precipitating reagents are obtained coated Hydroxide or oxide. The hydroxide can by subsequent heat treatment in Oxide can be transferred.

so with stearic acid Coated zinc oxide can be used advantageously as an aid for the production be used by elastomers. For example, for the production of tires.

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

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.

In one embodiment, a precursor of the product to be produced is precipitated by chemical reaction in the aqueous medium. To the surface coa Ting the precipitated precursor is, as described above, a hydrophobizing reagent dissolved in a water-miscible solvent to. The hydrophobic phase is separated and thermally treated, whereby a conversion of the precursor to the product occurs. The precursor can be, for example, carbonate, bicarbonate, hydroxide, oxalate, an ammonium compound or another thermally decomposable compound. The hydrophobizing reagent may be, for example, stearic acid. Excess reagent can be removed by distillation under reduced pressure. If, for example, cerium hydroxide is precipitated from an acidic cerium salt solution and hydrophobicized with stearic acid dissolved in ethanol, the coated precipitate product can be filtered off and thermally converted at 350 ° C. to nanoparticulate cerium oxide. Coating with stearic acid prevents the growth of nanoparticles during thermal treatment. Excess stearic acid may then be separated by vacuum distillation at below 250 ° C or by washing with an organic solvent such as ethanol. The cerium oxide can be used, for example, as a catalyst or as an abrasive.

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 the surfaces of Aluminum flakes, with transparent colored inorganic layers. Such coatings, the essentially made of hydrolyzable silanes, being on the usual Chromating can be dispensed with, are known. It will be According to the prior art usually alkoxyalkylsilanes, such as Trimethylethoxysilane or tetraethoxysilane or hydrolyzable Silanes used in which a non-hydrolysable radical a having polymerizable end. In particular for the production of colored, transparent coatings on aluminum can be used in Extension of the prior art described according to the invention metal oxide-containing 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.

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

A Application for according to the inventive method Prepared dispersions of hydrophobized particles is the Incorporation of the particles into a polymerizable monomer. It can the monomer may be, for example, acrylate or methacrylate and initially with of particle dispersion become. Using surfactants arise during the stirring unpolymerized acrylate beads as a dispersion in water, the Acrylate balls afterwards with the felled filled hydrophobic particles are and then stirring be polymerized. This gives microspheres of polymer with enclosed nanoparticles. The microspheres can for Incorporation in plastics or for simple production of paints, paints, cosmetic, pharmaceutical or medical Products are used. Is it the incorporated felled Particles around titanium dioxide, iron oxide or zinc oxide can be the Microspheres for example for the production of sunscreen preparations be used.

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 pumps. 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 produced.

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 by the meeting of liquid reactant jets in ei takes place in each case at least two fine liquid jets with beam diameter preferably between 50 microns and 2 mm, more preferably between 100 microns and 500 microns 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.

One another suitable microreactor can be prepared thereby, that five Components that are used thermally, by welding or by ultrasonic welding or by gluing together. The two outer components are structured plates with channels that act as supply lines for the Reactants serve and preferably made of plastic, but also of metal, glass or ceramic can exist. Two metal foils form after joining the components by means of Acting nozzles small holes from the supplied Reactants liquid jets, the jet-forming holes are aligned so that in each case 2 rays from opposite Meet slides. The films are preferably made of metal, however Also come in plastic, glass or ceramic plates in question. It can be at least one nozzle pair or multiple pairs of nozzles. Between the foils is the reactor component. It exists preferably made of plastic, but can also be made of metal, glass or Ceramics exist. It serves as a spacer between the nozzles and represents simultaneously in spatial Range of nozzle pairs each a mixing chamber available. This mixing chamber will realized by a respective hole in the spacer, the after the assembly of the components to the jet-forming nozzle holes concentric is and a width corresponding to the multiple of the nozzle width Has. The reactor component also has at least one on the mixing chamber perpendicular hole on the one hand as a supply for a flushing medium, as water or preferably air is used and on the opposite side as an exit for emulsion and rinsing medium serves. The conditioner does not have to be done simultaneously with the emulsification. The on the nozzle plate arranged nozzles can be distributed in two dimensions.

In another microreactor, the beam is formed with commercially available Metal tube, like used for example in stainless steel as syringe cannulas become. A cannula will within a limited range flattened by pressing or reduced in diameter. The reduced part and the adjacent ones Areas of the unreduced pipe section are in a thermoplastic Pressed plastic or poured into a curable plastic.

The Diameter reduction of the metal tube can also be done by at least a short pipe section a second one, if possible short metal tube with an outside diameter equal to the inside diameter of the first tube corresponds, in the first tube is fixed. The fixing can be done by welding, gluing, stapling or pressing respectively.

In the ends of the cannulas become two Feinkanülenabschnitte corresponding to an outer diameter the inner diameter of the cannulas and with a length less than 0.5 mm as nozzles fixed. The distance of the nozzles to the exit of the emulsion also less than 0.5 mm.

Instead of embedding in a hardenable Polymer can be a piece of pipe made of plastic or metal over pushed the reduced area.

These Embedding, as well as sliding over a piece of pipe serve primarily the fixation of the pipe ends, or the formed therefrom flat or round nozzles and take care of the safe cover of the colliding rays. This fixation is important if complete Cutting the diameter-reduced area into two segments is provided. Through a hole in the reduced area, a mixing chamber be produced between the resulting two nozzle ends. An opening the bore can be used as product outlet, the second opening as input for a flushing medium be used. The separation into two nozzle segments can also by a material-removing cut in the middle of the reduced part respectively.

Provided the two reduced pieces of pipe from a cut not complete can be separated from each other, can also be dispensed with an embedding become. In this case, the nozzle ends are mechanically still together connected so that ensures a concentric collision of the liquid jets is.

In In another exemplary embodiment, a cannula segment becomes a cannula segment pushed with an inner diameter corresponding to the outer diameter of the inner cannula. After pressing or squeezing the segment are through plane-parallel or wedge-shaped Cutting or tapping the segment section two nozzle openings for the generated to be mixed emulsion components and a product opening. Because of in this embodiment missing or very small dead space is not a flush required.

In any case, the direction of the colliding fluid streams by bending or kinking of the arrangement can be changed in the collision point of the liquids in their impact angle. The angle can differ from the original 180 degrees so far that the rays formed by the nozzles are no longer partially aligned with the opposite nozzle. For optimum coverage of the colliding rays, it is important that the rays lie in one plane. This is ensured by the function of a cladding tube or by an incomplete transection of the nozzle-forming constriction.

The Mixing the material streams can lead to emulsification of the ingredients. The present Invention may be flushing the afferent Channels, serve the mixing point and a subsequent mixing section.

In another embodiment be two consecutive cannulas on an ultrasound transducer or a piezo sounder fixed.

For precipitation reactions, where clogging can easily occur, the microreactor was called adjustable unit in three types of similar designs in which at least one of at least two cylindrical nozzle holders in the microreactor housing is mounted so rotatable and fixable that the liquid jets formed can be aligned to a collision point.

In the first version This type are the rotatable and fixable in the microreactor nozzle holders as cylindrical Calls aligned at an obtuse angle corresponding to the angle, in which the liquid jets produced therein to meet each other. The at least one nozzle holder, which rotatable is stored contains doing a nozzle stone, which is not centered in the nozzle holder located. The nozzle stone describes therefore, in the rotation required for adjustment, a circle, which overlaps with the desired adjustment with the counter-jet.

In the second embodiment of this type, the rotatably mounted nozzle holders may have a common axis of rotation. In this case, it is sufficient if a nozzle holder is fixed and at least one further nozzle holder is made adjustable by rotation. The nozzle block is then installed in the respective nozzle holder so that the beam formed deviates at an acute angle from the above-described, straight through beam. ( 6 )

In a third embodiment this type can be rotatably mounted nozzle holders to have parallel axes of rotation. The respective nozzle stone is also in the nozzle holder not placed in the middle. The dimensions are chosen so that it with the rotation of the nozzle holders to two positions of the beam overlap comes. In this version can the rays are directed towards each other in a 180 degree collision become.

In the three described embodiments of this Type, the microreactor can be adjusted respectively, without getting the entrance openings in the space coordinates move against. In this way adjustments can also be made in fixed blocks, as in microreactor kits meanwhile common are. These adjustable designs are above all advantageous if the nozzles, especially to avoid of potential blockages, have a large distance from each other should and therefore an exact alignment of the nozzles to each other by fixed Installation of the nozzles only unreliable to realize.

For a "scaling up "it is beneficial if a number of reactors can be operated in parallel. there then supplies a pump instead of a reactor several reactors with reactants. An emerging problem is the even distribution the amounts of reactants on the individual reactors. Only if this succeed, can Stoichiometric in the individual reactors guaranteed exact material conversions become. According to the invention therefore nozzles used, all of which have the same flow resistance, since the exact stoichiometric Distribution can only be guaranteed in this way. When Nozzles to be used in reactors Can you therefore metallic pipe sections of the same length and same inside diameter use. However, preference is given to using ceramic Nozzles off preferably alumina, in the version as sapphire or ruby or diamond nozzles, which are chemically highly inert and abrasion resistant. Alumina nozzles are Above all, well suited because the manufacturing tolerances extremely are small and the length the nozzle channel, the resistance of the nozzle decisively co-determined, commercially available in very short versions.

It is possible that the purge gas forms only due to pressure drop or higher temperature by changing the state of matter or by increasing the temperature in the microreactor. At least one of the product feeds can be heated above the boiling point of the solvent, so that the solvent then at least partially evaporated after passing through the nozzle because of the pressure drop there and is thus available as always forming and again condensable purge gas available. It is also possible that the gas forms by the chemical reaction itself or by targeted addition entspre additional reactants in addition to the reactants. In particular, this is 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, a connection for such an input, for example, is perpendicular to the illustrated section plane on the reaction space 3, while the output for the product and the flushing medium is, for example, also vertically below the illustrated section plane. At the respective outlet end of the product feeds is in each case a cross-sectional constriction. Essential for this invention is that the jet-forming cross-sectional constrictions, ie the nozzle lengths are very short and are preferably shorter than 1 mm. In this way, at low pressure loss, maximum product throughputs are achieved. It is important to use commercially available nozzles made of hard materials, preferably sapphire or ruby with clearly defined nozzle length and nozzle diameter. Upscaling by connecting several such nozzles in parallel does not result in an unequal distribution, since these nozzles are manufactured with very small error tolerances. therefore, it is an integral part of this invention that such nozzles be used.

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 limited in volume from a few milliliters up to several thousand liters become. The droplets of the mist forming in the collision then settle due to the 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, only in the dispersed Phase exists, kept small and backmixing and simultaneously the possibility prevents reactor clogging. The rinsing liquid can be silver oil, mineral oil or a other with the precipitation medium Do not mix immiscible medium.

The liquid jets are preferably produced in reactors by means of nozzles. To do this with pumps, preferably forcibly displaced Pumps, pressures between preferably 50-200 generated bar. Of course can also higher or lower pressures be applied. Lower pressures to lead however, to lower sales volumes, higher pressures to increase the Mixing speed but also to higher costs for the pump energy. The diameter of the reactor space should preferably be the multiple Diameter of the nozzles to the feeder correspond to the reactant beams. The factor is conveniently between 5 and 50, especially cheap is a factor between 10 and 25

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 Pressure transmitter, or a conductivity transmitter at the product output and a controller regulated.

Of the Period until complete Mixing can take place in such a microreactor, depending on nozzle widths, Pump pressure, reactant viscosity, temperature and other parameters below one millisecond can and can to under 50 microseconds by increasing the pump pressure or reducing it the nozzle diameter shortened if an extremely high nucleation rate is this required.

essential Part of the present invention is also the use of at least two flow reactors connected in series or preferred Microreactors, most preferably of flushable microreactors. In one definable distance is at the exit of the precipitation reactor, in which the first precipitation reaction is carried out, another reactor connected so that as purge gas for further Reactor derived from the first reactor gas product mixture serves. The reactants that collide in this further reactor be brought, serve the coating of the particles formed in the first reactor. The reactants colliding in the further reactor can be identical be or differ so that by hitting a product arises that prefers on the surfaces of the precipitated particles attaches or envelops these particles. If one falls for example an oxide or a hydroxide in the first reactor by chemical precipitation can this be coated in the second reactor characterized in that in a water-miscible solvent dissolved stearic acid is served. It can also be hot in place instead Water solved Sodium stearate become. The surface coating but can also take place by a chemical precipitation. In this Case find in two successive reactors each different chemical precipitation reactions instead of.

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 Clogged 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.

So far it is flushable Microactuators are as described in the present invention can, can these microreactors also quite generally for chemical reactions and reactions used in which the precipitation of particles not the The aim of the synthesis is, but blockages by encrustations or resinification or unwanted particle formation can be avoided should or to obtain a high yield on a particular fast mixing is important.

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 for the application of the method according to the invention are the production of particles by precipitation or co-precipitation of the following substances, or the coating of dispersed or freshly precipitated particles by subsequent precipitation or co-precipitation with at least one of the following substances, namely aluminum hydroxide, aluminum oxide, Aluminum silicate, aluminum titanate, antimony oxides, barium ferrite, barium stannate, barium sulfate, barium titanate and other 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, lanthana, Lithium titanate, magnesia, magnesium hydroxide, magnetofluids, manganese oxide, sodium aluminosilicate and other silicates, nickel hydroxide, nickel ferrite, nickel oxides, nickel sulfide, nickel titanium tanate, silver halides and other halides, silicon dioxide, strontium carbonate, strontium sulfate, titanium dioxide, yttrium aluminum garnet, yttrium vanadate, zinc oxide, zinc sulphide, zinc terephthalate and other terephthalates, tin oxide, zirconium phosphate and other phosphates, zirconium oxide and mixed metal oxides with the abovementioned substances, sometimes as Doping, as well as other perovskites, semiconductors, superconductors and other electroceramic materials.

So For example, materials for the electrodes of lithium-ion batteries can be used by precipitation and subsequent Create post-treatment. This succeeds among other things by the precipitation reaction of lithium compounds with compounds of the metals titanium, nickel, Cobalt, manganese and aluminum each alone or mixed. Lithium hydroxide can with an acidic salt of the aforementioned metals in a microreactor implement in order to arrive at phase-pure products.

The Precipitation described in the literature of lithium iron phosphate used as the cathode material in lithium ions Batteries to be used can also be beneficial in the like microreactors become.

By the reaction of barium hydroxide with an acidic titanium salt and After-treatment is achieved to pure phase barium titanate for electroceramic Applications. In the above examples, instead of lithium hydroxide or barium hydroxide also the corresponding respective acidic salt together with the acidic salts of titanium, nickel, cobalt, manganese and aluminum in the microreactor with an alkali, such as sodium hydroxide solution, to react.

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. For For the same or other purposes you can also use several consecutive precipitations in successive reactors, especially the precipitation of layers of iron hydroxides or oxides and silica in the foreground.

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 For example, it can be used as a dispersion or as a fresh precipitate one directly at the precipitation then, 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 also by the temporally slightly offset incidence of mixed oxides of tin or zinc with indium oxide or antimony oxide or of 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. Other examples include nano-cosmetics and nano-pharmaceuticals Solvent non-solvent 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 have. 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 so-called quantum dots and their coating. Particularly suitable as quantum dots and as their coating are: CdS, CdSe, CdTe, ZnS, ZnSe, ZnTe. As coating, phosphorus compounds are also suitable, for example trioctyl phosphine oxide or trioctylphosphine selenide.

One Another example is the preparation of nanoparticulate Polyanilindispersion by precipitation Aniline in hydrochloric acid with ammonium peroxydisulfate in hydrochloric acid solution.

A Application is the production of spinels as an intercalation electrode material for lithium-ion batteries. That's how it is For example, cobalt oxide from cobalt nitrate with excess lithium hydroxide in the presence of a surface modifier for steric stabilization of the resulting nanoscale particles. The surface modifier becomes a conductive coating during sintering under reducing conditions transformed. Further lithium hydroxide or lithium nitrate then reacts with Cobalt oxide to lithium cobaltate. To nanoscale, conductive coated Lithium titanate is obtained in an analogous manner, if instead of cobalt nitrate Titanium nitrate, or nitrous peptized, nanosize titanium oxide hydrate is used. To nanoscale, conductive coated lithium metal phosphate the electrode material is obtained by the precipitation of nanoscale iron phosphate, for example, iron nitrate and phosphoric acid in the presence of a surface modifier. Obtained by reducing sintering one from the surface modifier a conductive Layer. By the additional Presence of a lithium compound, preferably lithium hydroxide or Lithium nitrate, formed during further sintering of the nanoscale lithium iron phosphate intercalations Material that is on the surface electric conductivity having.

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.

One greater Advantage arises from the possibility described here, with nozzles to use exactly defined geometry. This also keeps it parallel Operation of multiple reactors uniform distribution and thus the Compliance with the exact stoichiometry guaranteed in all reactors.

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 In particular, these devices are particularly useful if in such reactions, as is very often the case, not in intended way to precipitations or incrustations can come.

Of 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. It is 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 is formed by the chemical reaction itself or by targeted addition of appropriate reactants in addition to the reactants. Especially come for that 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. 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 added with a time delay will give.

Explanation to the drawings:

1 - 6 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. The nozzles ( 2 ) may consist of hard material, such as carbides, nitrides. Or the nozzles may be short tube sections of syringe needles that become nozzles by being fixed as short tube sections of matching outside diameter into corresponding tubes of that internal diameter. Particularly suitable are also in the market in a wide variety of available nozzles of alumina, as sapphires or rubies. Also well suited, but more expensive, are diamond nozzles.

The housing body of 4 may in a preferred embodiment consist of two halves, each individual nozzle is fixed in one half and the halves are perpendicular to the plane of the colliding jets against each other and move to fix so that the rays can focus for optimal collision.

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.

6 and 7 show a microreactor ( 6 ) with at least two by rotation by means of adjusting screws ( 9 ) adjustable cylindrical nozzle inserts ( 7 ) with the nozzle ( 8th ) and the connection for reactant supply ( 10 ). This microreactor can have 2 or more inputs ( 10 ). In addition, this reactor has an input for purge gas or rinsing liquid ( 11 ) and an output ( 3 ). In 7 a version with 4 reactant inputs for liquid or dissolved reactants is shown. This type of reactor is particularly well suited if several reactants are to be reacted simultaneously and the precipitate tends to become blocked. This reactor is well suited, for example, for the preparation of azo dyes or for the precipitation of metal hydroxides or of metal oxalates. This reactor has a nozzle effect of the reaction space, which results from the fact that the air inlet opening is smaller than the product outlet and the colliding jets toward product outlet point. Not all liquid jets need to meet in a single point of collision. Thus, the angle of at least one outlet nozzle can be aligned so that the liquid jet formed by this nozzle only coincides in time with the reaction mixture from the collision of the other reactant jets. The lagging reaction component may be, for example, a halosilane which hydrolyzes as a coating.

Claims (39)

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 be generated in a continuous reactor and optionally this Particles within a definable, short temporal and, apparative seen, short spatial Distance, preferably in a continuous reactor by at least a chemical precipitation reaction or co-precipitation reaction on the surface be coated or modified. Method and device according to the preceding claims in that the resulting nanoscale particles on their surface thereby be modified that in addition 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 device according to the preceding claims, characterized in that an inorganic precipitation in a predominantly aqueous medium is carried out so that time equal to or immediately after the precipitation or at a definable time interval, seen from the apparatus, a definable spatial distance, together with an inert gas stream in organohalosilane gas, such as methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane or other halosilanes is fed and reacted, the precipitated phase is filtered off from hydrophobic coated particles and washed and then taken up in a high boiling solvent such as N-methylpyrrolidone and then the water still contained is at least largely distilled off and the remaining dispersion is used for incorporation into organic systems. Method and device according to the preceding claims in that in this way a whole series of hydroxides, Oxides, mixed oxides, silicates, titanides and other precipitates alone or as a coating on other supports nanodispersed in an organic medium can be obtained which can then be easily processed. Method and device according to the preceding claims in that the surface-modifying Reagent at least one surfactant, an anionic, cationic or nonionic surfactant, a hydrolyzable, reactive silane, preferred an alkoxyalkylsilane or an organic acid, an alcohol or a polymeric acid or may be at least one organic or inorganic compound, the on the surface the felled Coupled particles. Method and device according to the preceding claims in that as a medium for the precipitation Water serves as a surface coating selected organic reagent is a carboxylic acid or an alkali salt of a carboxylic acid and together with the Nanoparticles forms a water-immiscible, separable phase and the organic reagent dissolved in hot alcohol at the same time for precipitation or added a short distance after the precipitation. Method and device according to the preceding claims in that as a medium for the precipitation Water serves as a surface coating selected organic reagent is an alkali salt of a carboxylic acid and the organic Reagent for coating in hot Water dissolved becomes and coincides with the precipitation or added a short distance after the precipitation. Method and device according to the preceding claims in that as a medium for the precipitation Water is used and the pH value of the medium at the same time as the coating or after the coating in the acidic area is shifted. Method and device according to the preceding claims in that as a medium for the precipitation Water serves as a surface coating selected organic reagent is an alkali salt of a carboxylic acid and the organic Reagent for coating in hot Water dissolved becomes and coincides with the precipitation or added a short distance after the precipitation. Method and device according to the preceding claims in that the hydrophobic surface modification in the aqueous Milieu precipitated Particles simultaneously or subsequently by hydrolysis of volatile alkyl metal halides takes place and this serving otherwise as a flushing medium gas stream simultaneously as Transport medium for the volatile Alkyl metal halides is used and as a purge and carrier gas but also a preferably water-miscible solvent can serve, which is gaseous by heating and in the gas stream contained alkyl metal halide with the mist of the aqueous precipitate comes into contact while the alkyl metal halide with elimination the halogen group hydrolyzed and binds to the surface of the aqueous precipitation products. Method and device according to the preceding claim, characterized in that said hydrophobing surface modification for aqueous Particle dispersions of various nanoparticles, microparticles or macroparticles is used, wherein the particles are also platelets can, and lead through the coating to products, as in different Modifications as effect pigments, for example due to interference phenomena be offered on the market. Method and device according to the preceding claims in that as a medium for the precipitation Serves water and the amount of an 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 by chemical precipitation and optionally by an additional surface coating resulting particles are precipitated by a treatment with Nonsolvent from the solvent. Method and device according to the preceding claims in that nanoscale inorganic or organic products, which are preferably precipitated in a non-clogging microreactor or as purchasable Dispersion can be used, with at least one biodegradable Plastic, in particular a plastic such as polylactide or its co - glycolide Be coated by making these plastics water-miscible polar solvents such as dimethylacetamide, dimethylacetamide or N-methylpyrrolidone are dissolved and precipitated with preferably water or alcohol and such as Core-shell coated products as biodegradable products, for example for environmentally sound, technical consumables or for medical pharmaceutical products for in vivo applications for the transport of active pharmaceutical ingredients be used, as at least magnetic particles as a core can be used. Method and device according to the preceding claims in that at least two liquids through 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 from a mixing reaction of at least two solvent jets, preferred Water, in which the reactants dissolved in, colloidally dissolved, emulsified or dispersed state, and the solvent jets in an obtuse angle or at an angle of at least 180 degrees partly in at least one collision point or even more Collision points meet or in a pointed or dull Meet angle or hit against a baffle or from two nested nozzle tubes concentrically against hit a baffle and get 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 by that the microreactor is an adjustable reactor, where the nozzles in cylindrical, through Rotation by means of adjusting screws adjustable inserts, the nozzles a straight output or an acute angle output can form and outside the axes of rotation of the cylindrical Calls are located. Device according to the preceding claims, characterized by that for loading 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 by that loading the microreactor with the 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 value be managed. Device according to the preceding claims, characterized by that the colloidal dispersion of the precipitated products formed in the microreactor 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 device according to the preceding claims in that the dispersion formed in the collision space during the precipitation 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. A method and device according to the preceding claims, characterized in that the precipitation medium of the dispersion formed in the precipitation is evaporated by fed, heated gas, wherein the energy of the fed Th gas is sufficient by amount and temperature to a partial or complete evaporation and displaced by the gas and the resulting vapor from the collision space and the subsequent process section is designed according to a spray drying plant and the process is in its entirety as a precipitation process with integrated spray drying. 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 20 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 device according to the preceding claims in that in at least one of the liquid jets nanoscale or microscale, metallic or inorganic particles or platelets, those on their surface with the nanoscale precipitation products be coated. Method and device according to the preceding claims in that the optional with a 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 device according to the preceding claims in that the physical after-treatment remains the same 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 by that heated pressure pipes as feed lines for the Microreactor can be used and the heating optional over the critical pressure and the critical temperature of the reactant or one to his solution used solvent he follows. Device according to the preceding claims, characterized by that loading the microreactor with the 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. Method and device 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 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 oxide or metal hydroxide is formed and thus, for example, barium sulfate, magnesium sulfate or calcium sulfate alone or together, also as a coating with, for example, zinc oxide, magnesium hydroxide, aluminum hydroxide, antimony oxide or iron oxide, also as magnetic iron oxide. Method and device according to the preceding claims 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 device according to the preceding claims, characterized in that accompanied by precipitation of titanic acid or titanyl sulphate with at least one metal hydroxide or preferably at least one metal hydrogencarbonate salt-free nanoscale titanium dioxide is formed with at least one metal oxide or metal hydroxide. Method and device according to the preceding claims in that for precipitation from 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 in that particles are produced by precipitation or co-precipitation of subsequent substances, or coating of dispersed or freshly precipitated particles by subsequent precipitation or co-precipitation be carried out with at least one of the following substances, 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, magnesium hydroxide, magnetofluids, manganese oxide, Sodium aluminum silicate, Nickel hydroxide, nickel ferrite, nickel oxides, nickel sulfide, nickel titanate and other titanates, 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, Zirconium oxide and mixed metal oxides with the abovementioned substances, also as doping, as well as other catalysts, perovskites, semiconductors, Superconductors and other electroceramic materials, as well as nano-cosmetics and nano-pharmaceuticals or organic dispersions for coatings, and organic pigments are produced. Apparatus for the continuous production of nanoscale Products in a microreactor, characterized in that spinels as nanoscale intercalation electrode materials, in particular lithium cobaltate, lithium manganate, lithium titanate, lithium iron phosphate or lithium cerium phosphate or lithium vanadium phosphate based on particle surface electrically conductive are, as materials for lithium ion batteries getting produced. Apparatus for the continuous production of nanoscale Products in a microreactor, characterized in that electric 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 in that the Particles for 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 device according to the preceding claims in that the physical aftertreatment of the 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 chemical Products in a microreactor, characterized in that it itself encapsulated in a metal housing in the nozzles used in the reactor ceramic nozzles with exactly defined geometry. Apparatus for the continuous production of chemical Products in a microreactor, characterized in that the described device as a non-clogging chemical microreactor, instead of precipitation of nanoparticles, is used for chemical substance conversions. Apparatus for the continuous production of chemical Products in a microreactor, characterized in that the described device as a non-clogging chemical microreactor, instead of precipitation of nanoparticles used in chemical conversions which it does not intentionally cause precipitation or encrustation can come. Continuous precipitation of nanoscale products in microreactors