EP2027078A1

EP2027078A1 - Method for the production of porous carbon molds

Info

Publication number: EP2027078A1
Application number: EP07724720A
Authority: EP
Inventors: Karin Cabrera Perez; Philipp Adelhelm; Bernd Smarsly; Markus Antonietti
Original assignee: Max Planck Gesellschaft zur Foerderung der Wissenschaften eV; Merck Patent GmbH
Current assignee: Max Planck Gesellschaft zur Foerderung der Wissenschaften eV
Priority date: 2006-05-31
Filing date: 2007-04-28
Publication date: 2009-02-25
Also published as: JP2009538811A; WO2007137667A1; KR20090032050A; CN101454259A; US20090176079A1; CN101454243B; TW200804180A; CN101454243A

Abstract

The present invention relates to a method based on phase separation for the production of porous carbon monoliths, the monoliths produced according to the invention and the use thereof.

Description

Process for producing porous carbon moldings

The invention relates to a process on the basis of phase separation for the production of porous carbon moldings, the moldings produced according to the invention and their use.

Carbon-based monolithic materials are now used in a wide variety of technical fields due to their special material properties. Carbon monoliths have a relatively low weight in relation to many other materials, show high adsorption power, high thermal conductivity and high thermal stability and are usually sufficiently stable mechanically.

Carbon monoliths or carbon moldings are used, for example, as electrodes in fuel cells, as adsorbents for liquids and gases, as a storage medium for gases, as a carrier material in chromatographic applications or catalytic processes, as a material in mechanical engineering or in medical technology (DE 20 2004 006 867 W).

Porous or non-porous carbon monoliths can be made. For some applications, such as for use as a sorbent in chromatographic processes or as a storage medium, porous monolithic materials must be used with sufficiently large surfaces.

Porous carbon monoliths can be prepared in the simplest case by pyrolysis or carbonization of porous or foamed starting materials (eg, explained in DE 20 2004 006 867 W). However, it is almost impossible to influence the pore size distribution. US 2005/0169829 describes in the introduction the production of porous carbon monoliths by copolymerization of carbonizable compounds in porous silica monoliths as a template and the subsequent dissolution of SiO 2. In addition, a procedure for

Preparation of carbon monoliths with hierarchical pore distribution disclosed in which a carbon-forming agent is mixed with one or more particulate pore-forming agents as a template for the pores to be formed. After carbonation of the carbon former, the templates are removed to form a porous carbon monolith.

GB 2 157 482 discloses the preparation of porous carbon layers wherein the pores are produced by the addition of particulate pore formers which are burned out on carbonation.

DE 20 2004 006 867 U1 also discloses the use of particulate pore formers which can be washed out or burned out after formation of the monolithic shaped body.

Thus, in all cases, it is necessary to add template monoliths or template particles to the reaction mixture to produce carbon monoliths having particular pore size distributions. These methods are complicated and inflexible, since for each pore size other template molecules must be used. In addition, template monoliths and particles consisting of silica gel must be dissolved out by complex chemical processes (by dissolution with HF or NaOH) later. In addition, hierarchical pore size distributions are difficult to achieve, especially if, for example, for chromatographic applications, materials with interconnected macropores and mesopores in the walls of the macropores are to be produced. The object of the present invention was therefore to provide a process with which porous carbon monoliths with variable pore sizes and variable pore size distributions, in particular hierarchical bimodal or oligomodal pore size distributions, can be produced. It should by selecting the starting materials or the

Reaction conditions can be specifically influenced on the pore structure of the product. The task was also to develop carbon monoliths with large surfaces in order to obtain sufficiently large surfaces for interaction with different molecular species.

It has been found that porous carbon monoliths can be prepared by a phase separation process in which

a carbon former and an organic polymer are dissolved in an organic solvent at least partially, preferably completely,

during the evaporation of the solvent, during the concentration, at least partial phase separation takes place, which can continue during the carbonation, after removal of the organic solvent and the organic polymer by heating (eg pyrolysis, carbonization) and / or extraction of a porous carbon Material with mono-, bi- or oligomodal pore distribution is obtained, the pore structure is retained after the carbonization.

Without wishing to be bound by any particular reaction mechanism, it is believed that upon evaporation of the solvent and / or during one of the subsequent stages of material synthesis, microphase segregation occurs between the solid components (carbonator and organic polymer) on the one hand and the solvent on the other hand , This can be compared with a spinodal segregation, as for example for the production of silica gel monoliths according to a SoI-GeI method (Nakanishi, J. Porous Mater., 1997, 4, 67-112). Thus, the macroporous structures are likely to be generated by macroscopic phase separation between the carbonator and the organic polymer, while the microporous and / or mesoporous structures are removed by removal of the

Remains of organic polymer enriched areas can be generated.

The present invention therefore provides a process for producing porous monolithic carbon moldings by a) preparing a mixture containing at least one carbon former and an organic polymer in an organic solvent b) evaporating the solvent to a viscous or highly viscous mass or a c) optionally deformation of the mass obtained in step b) or

Shaped body d) heating the mass or the shaped body from step b) or c) to temperatures between 200 and 4000 ^° C.

In a preferred embodiment, pitch is used as the carbon former.

In a particularly preferred embodiment, mesophase pitch (mesophase pitch) is used as the carbon former.

In another preferred embodiment, polystyrene is used as the organic polymer.

In a preferred embodiment, a Lewis acid is added to the mixture in step a). In a preferred embodiment, the heating of the shaped body in step c) is carried out stepwise, initially heated to temperatures between 200 and 400 ° C and then to temperatures between 500 and 1000 ⁰ C.

In another preferred embodiment, a mixture is prepared in step a) which contains two or more different organic polymers of different molecular weight or an organic polymer in two or more different molecular weights.

In another preferred embodiment, one or more plasticizers are added to the mixture of step a).

In another preferred embodiment, the deformation in step c) is effected by extrusion.

In another preferred embodiment, an extraction is performed after step b) or step c).

In another preferred embodiment, the mass or the shaped body is activated before or during one or more of the steps following step b).

In a preferred embodiment, the porous monolithic carbon molded article obtained in step d) becomes another

Process step e) at least partially embedded in a sheath.

The present invention also provides porous carbon moldings produced by the process according to the invention. In a preferred embodiment, the moldings have at least one bimodal pore distribution with macropores and mesopores in the walls of the macropores.

In a preferred embodiment, the shaped bodies have a

Total porosity of 60 to 80% by volume.

In another preferred embodiment, the moldings have a surface area between 2000 and 3000 m ² / g.

In a preferred embodiment, the moldings are at least partially embedded in a sheath.

The present invention also provides a chromatographic separation column which contains a carbon molding according to the invention as a sorbent.

The present invention also relates to the use of the carbon moldings according to the invention as electrodes in electrochemical cells, double-layer capacitors or

Fuel cell, as an adsorbent for substances from liquids and gases (eg in the form of cigarette filters), as a storage medium for gases, as a carrier material in chromatographic applications or catalytic processes, as a material in mechanical engineering, as materials for flame retardancy, for thermal insulation, in the Sensors, as pigments and electronic materials or in medical technology.

A shaped body or a monolithic shaped body or monolith according to the invention is a three-dimensional body, for example in the form of a column, a cuboid, a sphere, a disk, a fiber, a regularly or irregularly shaped particle or any other irregularly shaped expression. Under the term Shaped body, monolithic shaped body or monolith also falls a layer of the material, for example on a surface or in a cavity.

Preferably, the monolithic moldings of the invention are columnar, i. cylindrical, or cuboidal or particulate.

A carbon shaped body is a shaped body which consists at least largely of carbon.

As carbon formers, it is possible to use substances which, directly or after carbonation or pyrolysis, produce a three-dimensional framework consisting predominantly of carbon. Those skilled in the art are aware of such carbon formers. Examples are pitches, in particular mesophase pitch (mesophase pitch), or furfuryl alcohol, fructose or naphthene. The carbon formers may be used singly or as a mixture of two or more carbon formers.

According to the invention, the term pitch covers viscous to solid, tarry or bituminous, fusible materials, which are e.g. to remain in the pyrolysis or distillation of organic matter (natural products) or of lignite or brown coal tar. In general, pitches are composed of high molecular weight cyclic hydrocarbons and heterocycles, which may have a molecular weight of up to 30,000 g / mol.

Mesophase Pitch is a type of pitch that consists of several predominantly aromatic hydrocarbons and contains anisotropic liquid-crystalline domains. For an overview of the preparation and properties of mesophase pitch, see Mochida et al., The Chemical Record, Vol. 2, 81-101 (2002). Mesophase pitch, for example, can be purchased from Mitsubishi Gas Chemical Company. As organic polymer, all organic polymers having a Hildebrandt solubility parameter between 8 and 12 can be used. Likewise, the term organic polymer includes mixtures of two or more corresponding organic polymers having different or equal molecular weights. Furthermore, mixtures which have an organic polymer in two or more different molar masses can be used as the organic polymer. The term organic polymer also includes copolymers or block copolymers such as, for example, polyoxyethylene glycol ethers ("Brij surfactants") or poly (ethylene oxide) -b-poly (propylene oxide) s. In a preferred embodiment, the organic polymer used is polystyrene. Methyl methacrylate (PMMA) is a suitable organic polymer The molar mass of the polymers used is typically between 500 g / mol and 1,000,000 g / mol, preferably between 10,000 and 500,000 g / mol. It has been found, however, that polymers with relatively large molecular weights can easily precipitate upon removal of the solvent and thus interfere with the phase separation.When mixtures of different polymers or mixtures of a polymer having different molecular weights are used, preference is given to a mixture of organic polymer having a molecular weight between 500 and 10,000 g / mol and a em organic polymer having a molecular weight between 50,000 and 500,000 g / mol used. By the choice of the organic polymer and its molecular weight or the

Molar mass distribution when using polymer blends, influence on the subsequent pore distribution in the molding can be influenced. The molecular weight and molecular weight distribution determine the separation structure during evaporation of the solvent and thus the porosity. Smaller molar masses lead to a later segregation and thus smaller pore systems. As the organic solvent, any organic solvents or solvent mixtures which sufficiently dissolve the carbonator and the organic polymer can be used. Furthermore, it is advantageous if the solvent can be evaporated off as simply as possible. Therefore, solvents with a low boiling point and / or high vapor pressure are preferred. Examples of suitable solvents are THF, CHCl ₃ or xylene.

Evaporation means according to the invention the at least partial removal of the organic solvent until the formation of a moldable mass. The evaporation can be done by simply allowing the mixture to stand, i. by evaporation, or accelerated by, for example, maximizing the surface area, e.g. is generated in a shallow container, the temperature is increased or negative pressure is generated.

Melt extrusion means according to the invention the introduction of a concentrated, moldable mass in the sense described in a heatable extrusion plant. In the extrusion plant, the phase separation can be completed and / or at least the burning out of the organic polymer can be started. The melt extrusion forms a shaped body.

Pyrolysis according to the invention means a temperature control or temperature treatment / heating. As a rule, in the process according to the invention, the organic polymer is at least partially burned out by pyrolysis, ie removed or converted into non-graphitic carbon or graphite. Carbonization is also a form of pyrolysis. Carbonization in accordance with the invention means the conversion of a carbon-forming agent into "non-graphitic carbon" carbon or possibly graphite.

To carry out the process according to the invention for producing porous monolithic carbon moldings, a mixture is initially produced which contains at least one carbon former and one organic polymer in an organic solvent. The amount of solvent is not critical because it is removed later by evaporation. Suitable mixing ratios (carbon former / organic polymer: organic solvent) are typically in weight ratios between 1: 100 and 3: 1, depending on the solubility of the carbon former or organic polymer in the organic solvent.

The mixture containing at least one carbon former and one organic polymer in an organic solvent is preferably a solution according to the invention. However, the mixture may also contain small amounts of undissolved carbon-forming agent and / or organic polymer, without the further execution of the process being disturbed. Furthermore, other non-soluble substances, such as inorganic pigments, particles or the like can be added to the mixture.

Furthermore, the mixture according to the invention may also be an emulsion. In the following, when the term "dissolve" or "dissolve" is used in connection with the preparation of the mixture containing at least one carbon former and an organic polymer in an organic solvent, "dissolve" or "dissolve" means that at least the most of the substances, preferably 70 to 95% of the respective component, but not necessarily 100% of the substances in

Be brought solution. If only a small proportion of a component can be solved, the whole or most of the remaining undissolved solid can be separated by filtration or centrifugation / decantation. Preferably, carbon formers and organic polymer are completely dissolved.

Carbon formers and organic polymers may first be separately dissolved in the organic solvent and then mixed or dissolved directly or simultaneously in the organic solvent.

As a rule, carbon formers and organic polymers are first dissolved separately in the organic solvent, since the solution properties of the components can be better taken into account. For example, when using pitches such as mesophase pitch, it may be that these components do not completely dissolve in the given amount of solvent. Then, one skilled in the art can decide if the amount of solvent should be increased or whether the undissolved portion before mixing with the organic polymer is e.g. to be separated completely or partially by centrifugation or filtration. The dissolution may also be e.g. by heating, vigorous stirring or sonication.

If separate solutions of the carbon former and the organic polymer are initially produced in the organic solvent, the preferred concentrations of these solutions are 10-70% by weight, more preferably 40-70% by weight of the carbon former, or 10 to 60 Weight%, particularly preferably 30 to 60% by weight of the organic polymer. The volume ratios between carbon former and organic polymer depend on the desired macroporosity. Typical volume ratios between carbon-forming agent and organic polymer are between 1: 0.1 to 1:10, preferably between 1: 0.5 and 1: 4. Accordingly, separate solutions of the carbon-forming agent and the organic polymer are preferably initially produced in the organic solvent. These two solutions are then combined with vigorous stirring. Typically, stirring is continued for a further 1 to 60 minutes after mixing.

Carbon formers and organic polymers can also be dissolved in various solvents if, after combining the two solutions, the final mixture of at least one carbon former and an organic polymer in an organic solvent is sufficiently homogeneous and no precipitation of either component is observed.

In addition, other substances can be added to the mixture of organic solvent, carbon-forming agent and organic polymer. These may be, for example, substances which influence the subsequent segregation, such as plasticizers, further solvents, surfactants, substances which influence the later carbonation behavior, such as e.g. Lewis acids such as FeCb, or Fe, Co, Ni or Mn (see Marta Sevilla, Antonio Fuerts, Carbon 44 (2006), pages 468-474), or substances containing the

Affect material properties of the later molded article, i. e.g. introduce certain functionalities into the molding. If these substances are not soluble in the organic solvent used, of course an emulsion or suspension is formed. When using Lewis acids, these are preferably used in an amount which corresponds to 0.1 to 10% by weight of the carbon-forming agent.

The preparation of the mixture which contains at least one carbon former and one organic polymer in an organic solvent can be carried out batchwise or continuously, for example by adding two separate solutions (consisting of at least carbon formers in organic form) Solvent on the one hand and at least organic polymer in organic solvent on the other hand) are mixed, for example, in a static micromixer.

After the preparation of the homogeneous mixture containing at least one

Contains carbon formers and an organic polymer in an organic solvent, the evaporation of the solvent is carried out until an at least viscous or highly viscous mass or a highly viscous or solid shaped body is obtained. The solvent can be partially or almost completely evaporated. The more completely the solvent is removed in this process step, the higher the viscosity of the green body becomes.

If you want to deform the green body, so you can do this, if the solvent is not completely evaporated and the green body is still viscous and directly moldable, or after complete or almost complete removal of the solvent by the highly viscous or solid green body by gentle heating again made more viscous and thus more malleable.

Through the container in which the solvent is evaporated, the shape of the resulting viscous mass or the shaped body, also referred to as a green body, is first determined. The green body may be heated directly after evaporation of the solvent without further treatment or deformation, or first or simultaneously, e.g. mechanically or thermally, deformed (for example by means of pressing,

Deformation or extrusion or melt extrusion). By extruding in particular moldings in the form of strands, lattices or hollow bodies can be produced.

The at least partial phase separation for forming the macroporous structures can be carried out both during evaporation of the solvent and during the mechanical or thermal after-treatment, for example Melt extrusion occur. As a rule, the phase separation already begins during the evaporation of the solvent and continues with a mechanical and / or thermal aftertreatment / deformation.

Likewise, an optional extraction step can be carried out before heating the shaped body to temperatures between 200 and 4000 ^° C. This extraction step may serve to extract an organic solvent which is difficult to completely remove by evaporation or to remove at least a portion of the organic polymer. Thus, the extraction step may replace all or part of the pyrolysis of the organic polymer. The extraction can be carried out with all aqueous or typically organic solvents or solvent mixtures. Depending on the purpose of the extraction, one skilled in the art will be able to select suitable solvents.

The molding is heated to temperatures between 200 and 4000 ^° C. This step is also called carbonization or pyrolysis, depending on the treatment conditions. The carbonation or pyrolysis can be complete or incomplete, depending on the duration or temperature during the treatment.

This means that the resulting carbon monolith is almost completely carbonated with complete carbonization and at least mostly carbon when incompletely carbonated.

Upon heating, the remaining organic polymer is burned out or carbonized to create a pore structure. Depending on the type of organic polymer, it may be that the organic polymer is almost completely burned out or a certain amount of residues (mainly carbon residues) remains from the organic polymer in the molding. In addition, heating also changes the structure of the carbon-forming agent. For the pitch preferred according to the invention or the mesophase pitch particularly preferably used as carbon formers, it is known that a certain order of the material occurs by means of a temperature treatment or carbonization. Comments can be found, for example, in Mochida et al., The Chemical Record, Vol. 2, 81-101 (2002). As a result of the temperature treatment, the graphenes grow laterally, and the graphene stacks grow in height. In addition, the degree of order of the graphene stack pack increases.

It has been found that the higher the carbonization temperature and the more complete the carbonization, the more the overall porosity is reduced, with the mesoporosity decreasing more. In a preferred embodiment, the heating is carried out at 200 to 4000 ° C with exclusion of oxygen, i. under an inert gas atmosphere. In particular, noble gases or nitrogen can be used. In a preferred embodiment, the heating of the shaped body is carried out stepwise, initially heated to temperatures between 200 and 400 ° C and then to temperatures between 500 and 1000 ° C.

The first temperature control at 200 to 400 ° C serves the cross-linking of the carbon-forming agent and thus the generation / maturation of the invention-relevant demixing structure. Typically, this temperature is maintained for 1 hour to 48 hours. Depending on the intended use of the carbon monolith, the thermal treatment of the molding can already be completed here.

Otherwise, it is then preferably heated to temperatures between 500 and 1000 ° C. in a second tempering step. Here is determined by duration of heating and the height of the temperature as completely the Carbonation should be carried out. Overall, the duration of the carbonization and the type of temperature profile during the carbonization can again influence the material properties such as carbon content and porosity.

After the at least partial evaporation of the organic solvent and before, during or after the heating of the viscous mass or of the shaped body can be additionally activated. Activation means according to the invention that the pore structure of the carbon molding and / or its surface is changed compared to a carbon monolith otherwise produced in the same way. Activation can be carried out, for example, by treating the green body before heating with substances such as acid, H ₂ O ₂ or zinc chloride, which attack the structure of the molding and in particular lead to a change in the pore structure during the subsequent heating or chemically alter the surface of the molding , Likewise, such substances may be added during heating or, for example, may be heated in the oxygen stream. Such forms of activation lead in particular to the formation of micropores or other chemical functionalization of the surface of the

Shaped body, for example, for the formation of OH or COOH groups by oxidation.

The activated or non-activated carbon monoliths obtained after heating can be used directly for further use or previously mechanically or chemically processed. For example, they can be cut to size by means of suitable saws or provided with chemical functionalities by chemical derivatization methods, ie activated. (It is also possible to coat the carbon monoliths completely or partially with a layer of, for example, an organic or inorganic polymer. It is thus possible in almost every step of the process according to the invention to influence the material properties of the later carbon monolith by adding certain substances or to introduce certain chemical functionalities. Even the solution in step 1 of the method according to the invention can, as described above,

Stabilizers, substances to assist the carbonization, inorganic particles or fibers, etc. may be added.

The green body can be treated in a similar manner, in particular if the solvent has not yet completely evaporated.

The porous monolithic carbon moldings according to the invention are distinguished by a specifically adjustable porosity. By their preparation by a process in which at least a partial phase separation takes place, they have a mono-, bi- or oligomodal

Pore structure on. In a monomodal pore structure in which the pores are generated in particular by the phase separation, typically either macro- or mesopores are present. Porous shaped bodies are preferably produced by the method according to the invention, which have interconnected macro- or mesopores, so that a flow of liquids or gases through the shaped body is possible. Size and number of meso- and micropores can be determined, for example, by the choice of the organic polymer, its concentration and molecular weight. The duration and temperature of the carbonation step can also influence the pore size or the

Pore size distribution are taken. The mesopore size can typically be set between 2 and 100 nm, preferably between 5 nm and 30 nm, the macropores typically have a size greater than 100 nm, preferably greater than 1 micron, more preferably between 1 and 5 microns. The pore sizes of the micro- and mesopores are determined by nitrogen physisorption, the macropores by means of mercury porosimetry or scanning electron microscopy. It can without any problem, overall porosities of more than 50%, preferably between 60 and 80% by volume, are produced while retaining the favorable mechanical properties.

Thus, the porosity of the carbon monoliths can be selectively adjusted over a wide pore size range and a hierarchical pore size distribution can be generated by the production method according to the invention. The specific surface area of the shaped bodies according to the invention is typically above 50 m ² / g. Preferably, materials with surfaces above 500 m ² / g, more preferably above 1000 m ² / g produced. Particularly preferred are porous moldings with surfaces between 2000 and 3000 m ² / g. The determination of the specific surface area is carried out by means of nitrogen adsorption. The evaluation is carried out according to the BET method.

The carbon moldings according to the invention may be unmodified or post-processed, for example, as electrodes in electrochemical cells such as double-layer capacitors or fuel cells, as adsorbents for substances of liquids and gases (for example as filters for air purification or in cigarettes)

Carrier material in chromatographic applications or catalytic processes, used as a material in mechanical engineering, as a storage medium for gases such as hydrogen or methane, as materials for flame retardancy, for thermal insulation, in sensors, as pigments and electronic materials or in medical technology.

In the field of fuel cells, the carbon moldings or powders produced therefrom can be used as constituents of electrodes, in particular for the storage of catalytically active nanoparticles and for gas transport. In particular, fuel cells require a sufficiently good conductivity of the carbon material. The carbon moldings of the invention have a sufficient Conductivity, in particular using mesophase pitch as a carbon-forming agent.

The shaped bodies according to the invention can furthermore be used in the field of chromatographic separation, in particular for

Applications with corrosive or redox-active substances, since the moldings are chemically and physically inert, for example against acids and bases. In addition, the moldings of the invention are suitable for chromatographic applications using electric fields. For these applications, the material should be in the form of a monolithic shaped body.

In addition, the shaped bodies according to the invention can be completely or partially embedded in a casing. According to the invention, a casing can be a holder or a three-dimensional molded body which has a recess into which the carbon molded body can be introduced completely or partially as accurately as possible. Accordingly, a shell may for example be a block of metal, plastic or ceramic, in which one or more carbon moldings may be wholly or partially inserted, clamped, glued or otherwise introduced.

In a preferred embodiment, a casing is a holder or a casing which completely or partially encloses the shaped body in a precise fit and thus enables the targeted contact of the shaped body with gases or liquids or in particular the targeted flow of gases or liquids through the shaped body. This type of sheath is known in particular from the field of chromatography. Here predominantly cylindrical porous shaped bodies are encased in such a way that gases or liquids can flow through the cylindrical shaped body in the longitudinal direction from one end face to the other. The sheath must fit accurately and dead volume. Furthermore, it must be so stable that even at higher liquid pressure no liquid except at the end faces of the sheath can escape.

The sheathing of the shaped body according to the invention can therefore according to

Methods are carried out, e.g. already be used for the production of chromatography columns. Suitable retainers and sheaths are e.g. known from WO 01/77660, WO 98/59238 and WO 01/03797. Suitable jackets with plastics may e.g. made of PEEK or fiber reinforced PEEK.

One way to produce such encased monolithic moldings, z. Example is to extrude the plastic onto the molding. In this case, the monolithic molded body is fed parallel to the extrusion of a tube through a crosshead. The freshly extruded tube encloses (hot) the molding and z. B. additionally pressed by a pressing device to the molding. It is also possible to heat a preformed tube instead of producing a tube by extrusion.

Due to the mechanical pressing and the additional sintering during cooling, a tight sheath is produced. It is also possible to introduce the shaped body into a prefabricated hose whose inner diameter is slightly larger than the outer diameter of the shaped body and then to heat the plastic, so that the hose can be pulled off to the final diameter, thereby tightly enclosing the shaped body.

In a further variant, the plastic casing is produced by flame spraying or single or multiple shrinking. Other injection molding or reflow processes are suitable. For use as a chromatography column or for other applications, the coated monoliths according to the invention can then be provided with appropriate fittings, filters, seals, etc.

The present invention therefore also relates to a chromatographic separation column which contains a carbon molding according to the invention as a sorbent. For this, the carbon monolith is typically first mixed with separation effectors, i. for example biomolecules, e.g. Derivatized enzymes, or metal catalysts such as platinum or palladium, or ionic, hydrophobic, chelating or chiral groups, and then prepared by encasing the resulting blank a ready chromatography column.

However, the shaped body can also be initially encased in its original form and then provided with an in situ process in the flow with the separation effectors.

In another embodiment, the monolithic shaped bodies according to the invention can find application in gas-tight containers or tanks for receiving, storing and dispensing at least one gas. Typically, such tanks must be designed to withstand pick-up, storage and discharge of gases at pressures of 45-750 bar.

The carbon moldings according to the invention are suitable for the storage and / or release of gases or gas mixtures which are present as gas, for example at room temperature or above room temperature. Examples are saturated or unsaturated hydrocarbons (especially methane, ethane, propane, ethylene, propylene, acetylene), saturated or unsaturated alcohols, oxygen, nitrogen, noble gases, CO, CO ₂ , synthesis gas or hydrogen.

Likewise, the monolithic molded bodies according to the invention can be used in a jacketed form in a fuel cell for receiving, storing and dispensing at least one gas (typically at pressures of 45-750 bar).

Owing to the high porosity and in particular in the preferred at least bimodal pore distribution with macropores and mesopores in the walls of the macropores, the monolithic carbon moldings according to the invention enable a much faster kinetics of reversible insertion / removal or adsorption than in the prior art. Desorption of various substances (eg analytes in the field of chromatography, gases or ions).

Even without further explanation, it is assumed that a person skilled in the art can make the most of the above description. The preferred embodiments and examples are therefore to be considered as merely illustrative, in no way limiting as in any way limiting disclosure.

The complete disclosure of all applications, patents and publications mentioned above and below, in particular the corresponding application EP 06011198.6, filed on 31.05.2006, is incorporated by reference into this application. Examples

1. Preparation of a carbon monolith according to the invention using polystyrene as organic polymer

Option A:

1.1 Preparation of precursor solutions:

Mesophase pitch (MP) in THF:

Mesophase pitch (Mitsubishi AR) is added with THF (weight ratio mesophase pitch: THF 1: 3) in a sealable recipient. To solve the mesophase pitch, follow with 20min ultrasound (100%) and shaking on a low intensity horizontal shaker. Alternatively, any other shaker or magnetic stirrer can be used. After about 7 days, centrifuging (10 min at 6500 rev / min), the solution then contains about 10 wt% MP. The undissolved mesophase pitch can be reused.

To initiate the carbonation even at lower temperatures, the MP solution is a Lewis acid, eg FeCb, added (1 - 10 wt% FeCl ₃ on the solids content in the MP solution). The solution is then stirred vigorously for 15 minutes.

The organic polymer, here polystyrene (PS) (MW 250,000, acros), is dissolved in THF.

(Weight ratio polystyrene: THF 1:20).

1.2 mixture of precursor solutions:

The polystyrene solution is added dropwise with vigorous stirring to the MP solution. The relative amount of polystyrene to MP determines the final absolute porosity of the material. The final solution is then stirred again for 30 minutes. 1.3 Formulation and shaping of the "carbon green body":

For demixing, the solution is poured into a Petri dish. After evaporation of the THF, a thin layer of a PS / MP mixture remains.

1.4 Carbonation:

The sample is partially crosslinked in the Petri dish 48 h at 340 ⁰ C and N _2. For a complete carbonation with structure preservation, a further annealing step at 500 - 750 ⁰ C may be introduced, but this depends on the intended application of the porous carbon material.

Characterization:

The carbon material thus obtained contains meso- and macropores

(determined by Hg porosimetry or scanning electron microscopy)

Variant B

1.1 Preparation of precursor solutions:

Mesophase pitch (MP) in THF:

Mesophase pitch (Mitsubishi AR) is added with THF (weight ratio mesophase pitch: THF 1: 3) in a sealable recipient.

To solve the mesophase pitch, follow with 20min ultrasound (100%) and shaking on a low intensity horizontal shaker.

Alternatively, any other shaker or magnetic stirrer can be used. After about 7 days, centrifuging (10 min at 6500 rev / min), the solution then contains about 10 wt% MP. Then the solution is diluted again with THF, so that the proportion of MP in the solution is about 2%. The undissolved mesophase pitch can be reused. The solution is then stirred vigorously for 15 minutes.

The organic polymer, here polystyrene (PS) (MW 250,000, acros), is dissolved in THF. (Weight ratio polystyrene: THF 1:60). To the carbonation of the mesophase pitch even at lower temperatures To initiate the polymer solution is a Lewis acid, eg FeCb, added (1 - 10 wt% FeCb bezgl. The total mass of polymer and mesophase pitch).

1.2 mixture of precursor solutions:

The polystyrene solution is added to the MP solution with vigorous stirring. The relative amount of polystyrene to MP determines the final absolute porosity of the material. The final solution is then stirred vigorously for about 12 hours.

1.3 Formulation and Forming of the "Carbon Green Body": For demixing, the solution is poured into a Petri dish or a crucible and, after evaporation of the THF, a thin layer of a PS / MP mixture remains.

1.4 Carbonation:

The sample is partially crosslinked for 10 hours at 300 ⁰ C (heating rate 1 K / min) under N _2. For a complete carbonation with structure preservation, a further annealing step at 500 - 750 ⁰ C may be introduced, but this depends on the intended application of the porous carbon material.

Porous bodies are also obtained by a temperature treatment at 340 ⁰ C for 48 hours (heating rate 1, 5 K / min)

Characterization:

The carbon material thus obtained contains meso- and macropores (determined by means of Hg porosimetry, N ₂ sorption or scanning electron microscopy) 2. Preparation of a carbon monolith according to the invention using PMMA as organic polymer

The preparation of the carbon monolith is analogous to Example 1, variant B. Instead of PS PMMA (MW 10,000-100,000) is used.

3. Preparation of a carbon monolith according to the invention using Brij 58 as organic polymer

The preparation of the carbon monolith is carried out analogously to Example 1, variant A, being used as precursor solutions in this case:

Mesophase pitch (MP) in THF: about 2g mesophase pitch (Mitsubishi AR) + 10g THF + 0.2g FeCl ₃

Solution of the organic polymer: 1 g Brij 58 + 20 g THF

Claims

claims

1. A process for producing porous carbon moldings by a) preparing a mixture containing at least one carbon former and an organic polymer in an organic solvent b) evaporating the solvent until a viscous or highly viscous mass or a corresponding molding is obtained c) Optionally deformation of the mass or of the shaped body obtained in step b) d) heating of the mass or of the shaped body from step b) or c) to temperatures between 200 and 4000 ^° C.

2. The method according to claim 1, characterized in that is used as carbon-formers pitch.

3. The method according to any one of claims 1 or 2, characterized in that is used as the carbon-forming agent mesophase pitch.

4. The method according to one or more of claims 1 to 3, characterized in that is used as the organic polymer polystyrene.

5. The method according to one or more of claims 1 to 4, characterized in that the mixture in step a), a Lewis acid is added.

6. The method according to one or more of claims 1 to 5, characterized in that the heating of the shaped body in step c) is carried out stepwise, initially heated to temperatures between 200 and 400 ⁰ C and then to temperatures between 500 and 1000 ⁰ C. ,

7. The method according to one or more of claims 1 to 6, characterized in that in step a), a mixture is prepared, the two or more different organic polymers of different molecular weight or an organic polymer in two or more different molecular weights.

8. The method according to one or more of claims 1 to 7, characterized in that the mixture from step a) one or more plasticizers are added.

9. The method according to one or more of claims 1 to 8, characterized in that the deformation in step c) is effected by extrusion.

10. The method according to one or more of claims 1 to 9, characterized in that after step b) or step c) an extraction is carried out.

11. The method according to one or more of claims 1 to 10, characterized in that the mass or the shaped body is activated.

12 .. The method according to one or more of claims 1 to 11, characterized in that the porous carbon molded body obtained in step d) is embedded in a further process step e) wholly or partly in a sheath.

13. Porous carbon molded article produced by the process according to one or more of claims 1 to 12.

14. Porous carbon molding according to claim 13, characterized in that the molding has at least one bimodal pore distribution with macropores and mesopores in the walls of the macropores.

15. Porous carbon molding according to claim 13 or 14, characterized in that the shaped body has a total porosity of 60 to 80% by volume.

16. Porous carbon moldings according to one or more of

Claims 13 to 15, characterized in that the shaped body has a surface between 2000 and 3000 m ² / g.

17. Porous carbon molding according to one or more of claims 13 to 16, characterized in that the shaped body is at least partially embedded in a sheath.

18. A chromatographic separation column containing a porous carbon molding according to one or more of claims 13 to 16 as sorbent.

19. Use of a porous carbon molding according to one or more of claims 13 to 17 as an electrode in electrochemical cells, double-layer capacitors or fuel cells, as an adsorbent for substances from liquids and gases, as a carrier material in chromatographic applications or catalytic processes, as a storage medium for gases, as a material in mechanical engineering, as materials for flame retardancy, for thermal insulation, in sensor technology, as a pigment, electronic material or in medical technology.