DE10218278B4 - microreactor - Google Patents

Abstract

Microreactor consisting of a tight envelope with at least one inlet and one outlet opening, wherein within the wrapping one or more open-cell, three-dimensional microstructured network (s) is / are, the network (s) only of glass, Metal or ceramic or of compounds or of composites thereof Existing materials, mesh or Cell widths of ≤ 500 μm and open porosities of ≥ 50 % By volume, and wherein the one or more open-cell / -n, three-dimensional microstructured / -n network / a microstructuring show in the form of three-dimensional in all spatial directions arranged cavities is / are executed, the ratio of cavity volume to network volume is greater than 1, and wherein in the or the open-cell, three-dimensional microstructured Network formed dwell, mixing and reaction sections or spaces are.

Description

The The invention relates to a microreactor and relates to areas chemical engineering and ceramics, the microreactor for example the synthesis of active substances or hazardous substances are used can.

microreactors win because of their advantages compared to macroscopic ones chemical reactors are becoming increasingly important as they are, for example shorter Response times, lower chemical consumption and a lower Have space requirements.

typical Functions of microreactors consist in the mixing of gases and Liquids, their tempering (heating / cooling), and the setting of a defined residence time of the gases / liquids or their mixtures and reactants. This function is realized through the geometric design of microvolumes in which the Gases / liquids be passed, stay, be mixed, react. typical Dimensions of the volume structuring in microreactors are lateral in the range of 10-500 μm, where length, Width and height ratio each vary greatly according to function of the micro-volume and in one dimension often reach the dimension of several mm. The surfaces of the Microvolumes are sometimes designed specifically to z. B. the intensive To enable contact with an applied catalyst Etc..

typically, microreactors are made according to the prior art, in into the respective materials (eg metal, ceramic, plastic), from which the microreactor is built up, free micro volumes, d. H. wells be introduced. This can be done by micromachining, such as milling and Laser processing, by etching, by embossing or by molding previously with similar ones Process produced prototypes or negative forms done (W. Ehrfeld et al. DECHEMA monographs Vol. 132, Verlag Chemie Weinheim, Pp. 1-28, 1996).

By These structuring techniques result in high creative freedom the microcavities in the area, d. H. in x-y direction while in the 3rd dimension (z-direction) are severely limited; mostly the structuring depth is limited, or only inaccurately adjustable, and only goes at an angle of 90 ° or only with small deviations of 90 ° from the x-y surface in the Depth. Undercuts are usually not possible, but only by assembling differently shaped parts, for example, by closing a channel structure with an intermediate layer possible.

One Another disadvantage of these manufacturing methods is that the ratio of Volume of the cavities to the surrounding material from which it is made, usually very is low, rarely greater than 1. This preserves the microreactor has a number of disadvantageous properties, e.g. B. a high heat capacity, what for the introduction or dissipation of heat of reaction unfavorable is.

By these restrictions Structuring on essentially 2 dimensions is the effectiveness the cavities for the intended function restricted and it has to very many and / or very long cavities introduced into the surface become. This grows either the size of the microreactor, which contradicts the meaning of this technique, or the compulsion increases for further miniaturization of the cavities in the x-y direction, which the difficulties of manufacture and the cost of microreactors greatly increased.

A different possibility is, as possible many cavities next to each other or on top of each other (by stacking planar structured elements) in the microreactor to arrange (H. lion and W. Ehrfeld, Electrochimica Acta, Vol. 44, Issues 21-22, 1 June 1999, pages 3679-3689). This increases the constructive Hassle for a uniform distribution of gases / liquids on all cavities would be required if, for example, same residence times are necessary therein. Also need elaborate distribution and inlet lines made and in the micro-reactor be arranged in front of or behind the actual function cavities. These Elements must also manufactured with the known Mikrostrukturierungsmethoden be, shrink that for the functional cavities available Volume of the microreactor in addition and increase the production costs.

To WO 99/64158 A1 is a reactor carrier with several microsampling chambers for free-flowing samples known, in which the individual chambers have a porous wall and this individual chambers separated by a tight envelope are arranged. By the projecting from the tight envelope part of the porous wall the chambers become the liquid recorded and forwarded to the samples. This finds the desired chemical reaction in the free volume of the chamber with the sample and not with and in the porous Wall instead.

By Hentze, H.-P. and Antonietti, M. (Review in Molecular Biotechnology, Vol. 90, Issue 1, March 2002, pp. 27-53) has published a review of porous polymers and resins for biotechnological and biomedical applications. It states that the main applications of such, including foamed Materia in chromatography and membrane technology, future work could focus more on chemical and geometrical domains (nano- and micro-reaction technologies).

Kursawe, A. and Hönicke, D. (Catalysis Communications 2 (2001) 347-351) have studied the effects of NO ₂ and Cs in the partial ethene oxidation in Ag / Al microchannel reactors using the silver-coated Al microstructure of the reactors acts as a catalyst.

Generally are also known from Ullmann's Encyclopedia of Industrial Chemistry (4th Edition, Volume 3, Process Engineering II and Reaction Apparatus, Verlag Chemie, Weinheim / Bergstr., 1973) also technical equipment, the reaction vessels, such Tanks, kettles and pipes can contain. The case with the reaction materials in contact are metallic materials, plastics or glass.

One new microreactor for a high throughput in the continuous synthesis of organic Materials is from G.M. Greenway u.a. (Sensors and Actuators B: Chemical, vol. 63, Issue 3, 15 May 2000, pp. 153-158) and applied. The catalytic reaction in microchannels of 300 μm width and 115 μm Depth performed. The microchannels are etched into a glass and covered with a plate. In the microchannels was itself a microporous Silicate structure, which as a micropump and as a portable recording for the Catalyst worked.

Farther are after Dubbel, paperback for mechanical engineering, 20th ed., Springer, 2001 numerous bioreactors known, made of glass, metal or other materials, like earthenware or wood. They come as reactors fixed biomass fixed-bed, or fluid bed or membrane reactors used in which multi-phase reactions can take place.

Also known is after DE 197 53 249 A1 a ceramic network consisting of three-dimensional interconnected ceramic webs, wherein the cavities in the ceramic webs have a round or nearly round cross-section.

task The invention is to provide microreactors, which have a have three-dimensional microstructuring.

These Task is solved by the features of claim 1. Advantageous embodiments are in the subclaims specified.

Of the Microreactor according to the invention consists of a tight envelope with at least one inlet and one outlet opening. Inside the enclosure is / are one or more open-cell / -s, three-dimensional microstructured / -s Network / -e arranged, whereby the network / s only from glass, metal or ceramics or compounds or composites of these materials existing meshes or cell widths of ≤ 500 μm and open porosities of ≥ 50% by volume demonstration-t / s. That or one or more open-cell / -n, three-dimensional microstructured network (s) continue to microstructure on, arranged in the form of three-dimensional in all spatial directions wells accomplished is / are, the ratio of cavity volume to network volume is greater than 1. Also are in the open-cell or the three-dimensional microstructured Network formed dwell, mixing and reaction sections or spaces.

advantageously, are as a network, a ceramic network, an open-cell ceramic foam, a open-cell metal foam and / or open-cell glass foam used.

It is also advantageous if the ceramic network or the open-cell foam ceramic consists of Al ₂ O ₃ or SiC.

Also Advantageously, the cladding of glass, ceramic or Metal or compounds or connected by them or from the same, but dense material, such as the network, with the wrapping whole or partially made of an optically transparent material can.

Farther Advantageously, the network consists of one with metal or Glass partially filled Ceramic network or ceramic foam.

It is also advantageous if the mesh or cell widths between 20 and 300 μm be.

Advantageous is also when the network within the enclosure different mesh or Cell widths has.

Farther it is advantageous if the open porosity between 75 and 90 vol .-% lies.

Especially it is advantageous if the ratio of Kavitätsvolumen to network volume is between 3 and 10.

Also It is advantageous if the surface of the network structures to increase the surface area is.

Furthermore, it is advantageous if the network of a catalytically active material completely or partially or is completely or partially coated with a catalytically active material, wherein the catalytic material can be photoinitutable, radiation-initiated, chemically initiated, thermally initiated.

It is also beneficial if the material of the network is whole or partially made of an electrically conductive material.

Also It is advantageous if there are more openings in the enclosure for sensors or actuators are present.

Also Advantageously, multiple networks within the enclosure are through dense or microporous Separating layers separated with a pore size between 2 nm and 1 micron arranged.

And it is also advantageous if the network is anisotropic Microstructuring has.

at consists of the microreactors according to the invention the network of a material with three dimensions in all spatial directions repeatedly repeated microcavities with structure widths in all three spatial directions of ≤ 500 μm, where The relationship of cavity to the material volume> 1 (advantageously> 3,> 8). It will as a network uses a material which in the form of an open-cell, Three-dimensional microstructured network with mesh or Cell widths ≤ 500 μm and one open porosity of> 50 vol .-% is present.

Three-dimensional microstructured open-cell networks can be produced with cell widths of ≤ 500 μm. They can be made of glass, metal or ceramic or of compounds or composites of these materials. They have a ratio of cavity to material volume, which is significantly greater than 1 and is typically 3 to 10, advantageously 7 to 9. Networks, in particular open-cell foams, have a very good cross-mixing capability of gases or liquids flowing through. Through the mesh or cell width, the pore volume and the dimensions of the respective network / foam, the flow resistance can be varied, resulting in defined dwell distances for flowing liquids / gases depending on their viscosity. The surface of microstructured open-cell networks / foams is very high (7000 to 10000 m ² / m ³ ) and can be further increased by coating the network / foam-forming materials with additional microporous materials (so-called washcoats) and, for example, provided with catalytically active substances become.

Next the usual catalytically active coatings can, for. B. also photocatalytically active Coatings applied to the network / foam-forming material and the dense walls of the microreactor optically permeable, whole or also with viewing windows, be designed so that on the external stimulation Photocatalysts are triggered with a special light source can. This is especially possible because of the high porosity the networks / foams a deep penetration of the light into the cavities of the network / foam and thus to the surface the photocatalytically coated materials is possible.

Networks / foams off electrically conductive Materials can be about that Apply a voltage directly electrically heated or in be heated indirectly in a microwave field. Networks / foams off Materials with high thermal conductivity can be heated indirectly or chilled become.

One Microreactor made of open-cell, three-dimensional microstructured Network can be made by using a glass, metal or ceramic foam with a tight envelope made of metal or ceramic, with corresponding openings for the Inlet and outlet of liquids / gases is provided.

Farther For example, a microreactor can also be made by placing it in a thin-walled Container off Metal, glass or ceramics, which are combined with the o. G. Openings is provided three-dimensionally microstructured foam body is introduced. Or the dense envelope arises already during the foaming of the Material (so-called molded foam) on the vessel walls of the mold, in the the foam foamed becomes.

By the combination of foams different fine or dense cell widths and materials perpendicular or parallel or oblique to the flow direction can different effects (eg, successive mixing, reacting, tempering, Separate) can be combined in a microreactor. It can too same foams coated and combined with different catalysts.

It is possible, too, different or identical networks / foam bodies with dense or microporous separation layers to separate each other inside the reactor, so different reaction spaces from each other demarcate or a forced operation from flowing through Gases / fluids to reach.

Another advantage of using mi CROSTRUCTURED NETWORKS / FUSES is that they can also be provided with anisotropic structuring by being deformed. This results in a stretching or compression of the mesh or cells in one direction and thus directional properties, eg. B. Durchströmungswiderstand, thermal and electrical properties, etc .. This deformation can also take place continuously over a certain dimension, so that there is a gradual change in the anisotropy and thus geometrically graded properties arise.

Farther the use is foam-like Three-dimensional microstructured materials possible and meaningful, as z. B. by textile techniques of metal wires, ceramic and glass fibers or indirectly made of glass and ceramics can.

Farther can have openings for the introduction be mounted by sensors, etc.

For the production the networks can too generative procedures, such as B. SLS (Selective Laser Sintering), 3DP (3D Printing), FDM (Fused Deposition Modeling). In this case, the geometric design of the networks are not Set limits. It is also possible that by laminating punched and three-dimensional shaped Films such networks can be produced. In this case that is Network easily on planar claddings adaptable.

The positive Connection of two or more parts of the enclosure is for example by laser welding or by joining foils possible.

in the Further, the invention will be explained in more detail in several embodiments.

Example 1:

One cuboid Microreactor is composed of a network whose cavities like follows are constructed: Each cavity consists of a cavity with a diameter of about 300 microns, adjacent is of an average 12 similar cavities, the opening to the neighboring cavities a roughly circular Cross section has a mean diameter of about 160 microns. The network itself consists of thin rods of alumina ceramics, the average about 50 microns thick and approx. 120 μm are long. Each of these four rods are in their own Endpoints interconnected so that they are the described wells form. The relationship the volume of the cavities to the volume fraction of the network forming rods is about 5.25, which is an open porosity of the network of 84%.

The wells extend repeatedly in all three spatial directions; about 80 wells in the x-direction, about 40 in the y-direction and about 12 in the z-direction, which a body the dimensions of about 20 × 10 × 3 mm. The side surfaces of the body are made of dense aluminum oxide ceramic surfaces, which have an additional thickness of 1 mm have formed.

at 3/4 of the network, d. H. in a volume of 15 × 10 × 3 mm the surface the ceramic sticks with a network of fine trenches provided, which are about 100 nm wide and 10 nm deep. On the surface of the Ceramics in the sub-volume of the network is a few nanometers thin layer applied by very fine platinum particles.

At the faces of the microreactor forming surfaces, d. H. the two opposite y-z outer surfaces of the Microreactor, is centered or centrally offset one round outlet opening and two inlets with a diameter of 1 mm. Directly to the two inlet openings closes the uncoated part of the network so that the incoming media only after the passage of 20 cavities in the x-direction with the catalytic effective platinum on the surface get in contact with the network. The microreactor serves as a catalytic supported Mixing and reaction path, which when flowing with a liquid or gaseous Medium depending on its viscosity has a defined residence time and reaction time.

Example 2:

A microreactor is made up of a combination of two different networks. Network 1 is composed of cavities as described in Example 1. On the surface of the alumina ceramic rods of the network, a few nanometers thick layer of very fine titanium oxide particles is applied. The cavities extend repeatedly in all three spatial directions; about 80 cavities in the x direction, about 80 in the y direction and about 12 in the z direction, resulting in a body of dimensions of about 20 × 20 × 3 mm. The side surfaces xz and yz side surfaces of the body are formed of dense alumina ceramic surfaces having an additional thickness of 1 mm. In the end faces of the microreactor forming surfaces, ie, the two opposite yz outer surfaces of the microreactor a circular outlet opening and inlet opening with a diameter of 1 mm is mounted centrally. The xy top of the Network is bounded by a transparent, 1 mm thick sapphire disk, the bottom of a porous alumina ceramic surface with a pore width of about 50 nm. This is followed by network 2 with cavities, consisting of a cavity with a diameter of about 250 microns, adjacent is of a mean 12 similar cavities, the opening to the adjacent cavities has an approximately circular cross section with an average diameter of about 120 microns.

The Network itself consists of thin rods Alumina ceramics, which are on average about 50 microns thick and about 100 microns long. Four of these sticks are connected in their respective endpoints so that they the described cavities form. The relationship the volume of the cavities to the volume fraction of the network forming rods is about 3, which is an open porosity of the network of 75%. The cavities extend repeatedly in all three spatial directions; about 100 cavities in x-direction, about 100 in the y direction and about 15 in the z direction, resulting in a body of Dimensions of about 20 × 20 × 3 mm results. The side surfaces of the body are down to the top x-y area made of dense aluminum oxide ceramic surfaces, which have an additional thickness of 1 mm own, formed. At the end faces of the microreactor forming surfaces, d. H. the two opposite y-z outer surfaces of the Microreactor, is centered in each case with a round outlet opening and inlet opening Diameter 1 mm attached.

Of the entire microreactor thus has the dimensions of 22 × 22 × 9 mm. The two networks form two reaction and residence spaces, through the porous one Intermediate layer communicate. In the upper room can through irradiation with UV light from outside through the sapphire surface photocatalytic reaction at the titanium oxide surface of the rod with the through the upper inlet opening supplied Medium be initiated. While a portion of the reaction products through the upper outlet the reaction space leaves and Z. B. is recycled in the circuit, another comes Part of the reaction products through the porous intermediate layer in the second Reaction space and is there with another, through the lower inlet port supplied Medium mixed or reacted further.

Example 3:

One cuboid Microreactor is composed of a network whose cavities like follows are constructed: Each cavity consists of a cuboid Cavity with a dimension of approx. 100 μm in x-direction, approx. 80 μm in y-direction and approx.

300 μm in z-direction. The network itself consists of thin rods of silicon carbide ceramics, the average about 25 microns are thick and form the edges of the cavities. The ratio of Volume of the cavities to the volume fraction of the network forming rods is about 9.2, which is an open porosity of the network of 90%.

The wells extend repeatedly in all three spatial directions; about 200 wells in the x-direction, about 125 in the y-direction and about 10 in the z-direction, which a body the dimensions of about 20 × 10 × 3 mm. The side surfaces of the body are made of dense silicon carbide ceramic surfaces, which have an additional thickness of 1 mm have formed.

At the faces of the microreactor forming surfaces, d. H. the two opposite y-z outer surfaces of the Micro reactor is centered in each case with a round outlet or inlet opening Diameter 1 mm attached. The microreactor serves as a temperature-controlled Indwelling and reaction zone, which flows through with a liquid or gaseous Medium depending on its viscosity has a defined residence time. Due to the good thermal conductivity of the Silicon carbide ceramics can be used for cooling or heating by an applied to the outer xy surfaces self-regulating heating / cooling element be made.

Example 4:

One cuboid Microreactor is composed of a network as in Example 3. The outer ones wells are filled with a borosilicate glass, so that a dense outer wall made of borosilicate glass. additionally are each about 500 cavities in the corners of the cuboid Borosilicate glass filled, whereby the space formed by the free cavities to the two yz end faces evenly narrowed. The relationship the volume of the cavities to the volume fraction of the network forming rods is about 9.2, which is an open porosity of the network of 90%. The ratio of open to borosilicate glass filled wells is about 3.3.

At the faces of the microreactor forming surfaces, d. H. the two opposite y-z outer surfaces of the Micro reactor is centered in each case with a round outlet or inlet opening Diameter 1 mm attached. The microreactor serves as a mixed, Residence and reaction path. Through the closed corners of the cuboid Microreactor results in a particularly good management and mixing of the supplied media.

Claims (18)

Microreactor consisting of a tight enclosure with at least one inlet and one outlet opening, wherein within the wrapping one or more open-cell / -s, three-dimensional microstructured / -s Network / is arranged / are, whereby the or the network / s only of glass, metal or ceramic or of compounds or of Connected to these materials are / mesh size or cell widths of ≤ 500 μm and open porosities of ≥ 50 vol.% and the one or more open-cell / -n, three-dimensional microstructured / -n network / microstructuring exhibited, arranged in the form of three-dimensional in all spatial directions wells is / are executed, the ratio from cavity volume to Network volume is greater than 1, and wherein in the or the open-cell, three-dimensional microstructured Network formed dwell, mixing and reaction sections or spaces are. A microreactor according to claim 1, wherein as a network a ceramic network, an open cell ceramic foam, an open cell Metal foam and / or an open-cell glass foam are used. Microreactor according to claim 2, wherein the ceramic network or the open-cell foam ceramic consists of Al ₂ O ₃ or of SiC. A microreactor according to claim 1, wherein the enclosure is made of Glass, ceramic or metal or compounds or composites thereof Materials exists. A microreactor according to claim 4, wherein the enclosure is made of the same but dense material as the network is made up of. A microreactor according to claim 4, wherein the casing is whole or partially made of an optically transparent material. A microreactor according to claim 1, wherein the network from a metal or glass partially filled ceramic network or Foam ceramic exists. Microreactor according to claim 1, in which the mesh or cell widths between 20 and 300 microns. A microreactor according to claim 1, wherein the network inside the serving has different mesh or cell widths. A microreactor according to claim 1, wherein the open porosity between 75 and 90% by volume. A microreactor according to claim 1, wherein the ratio of cavity volume to network volume is between 3 and 10. A microreactor according to claim 1, wherein the surface of the Structured network for surface augmentation is. A microreactor according to claim 1, wherein the network consists of a catalytically active material wholly or partially or with a catalytically active material wholly or partly is coated. A microreactor according to claim 13, wherein the catalytic Photoinitizable, radiation-initiatable, chemically-initiatable, is thermally initiated. A microreactor according to claim 1, wherein the material of the network wholly or partly made of an electrically conductive material consists. A microreactor according to claim 1, wherein further openings in the serving for sensors or actuators are present. A microreactor according to claim 1, wherein multiple networks inside the serving by dense or microporous Separating layers are arranged separated. A microreactor according to claim 1, wherein the network has an anisotropic microstructuring.