DE102005032345A1 - Channel-containing shaped body for use in filters for vehicles has a glass-containing amorphous inorganic support for the adsorption agent - Google Patents

Abstract

A shaped body comprising an adsorption agent in and/or on an at least partially amorphous inorganic support structure is such that (A) the support is of or includes glass; (B) the amorphous fraction of the support makes up 25-60 wt.% of the total weight of the shaped body; and (C) the shaped body contains channels. An independent claim is also included for production of the body by (1) mixing the adsorption agent, a support -yielding material characterized as per (a) and (b) above, plasticizer, liquid phase and optionally other additives; (2) forming the mixture to give a channel structure; (3) heating the body to at least the melting temperature of the support material; and (4) cooling so as to form an amorphous support structure.

Description

The The invention relates to an adsorptive molding, a process for the preparation thereof as well as the use of the shaped body in a filter system, preferably in a motor vehicle.

adsorptive Moldings, especially in channel structure and on the basis of activated carbon preferably in filter systems for removing hydrocarbons used from a stream of air. In particular, adsorptive shaped bodies are used in the automotive industry, preferably in tank ventilation systems, used. The channel structure can be obtained by extrusion and has a big one contact area per volume. Due to the channel structure you get against granulated activated carbon or extruded shaped carbon significantly improved adsorption dynamics or adsorption kinetics.

From the US 5,488,021 is an activated carbon molded body known. Bentonite, attapulgite or kaolin serves as the matrix for embedding the activated carbon. As additive cellulose ether is added as a green binder. Since the shaped body is dried at a maximum of 100 ° C and not sintered, the cellulose ether is not thermally destroyed and limits the capacity of activated carbon.

The shaped body with channel structure, in the US 5,914,294 is produced via a ceramic sintering process. In this case, pulverulent activated carbon is mixed with a ceramic-forming material and together with a flux and sintered after shaping and drying under protective gas. Although the flux reduces the sintering temperature, but temperatures of over 1000 ° C must be used to ensure sufficient strength and water insolubility of the molding.

The drying process of in the US 5,914,294 described method is of great importance. Due to the different fast-drying materials in the molding, the molding must be dried slowly to avoid cracks. Therefore, the relative humidity of the molded body is lowered in a controlled manner during drying in order to avoid stresses. Drying is by vacuum drying or freeze-drying and generally takes about 24 hours.

In the US 5,543,096 In addition to clay, a silicone resin is used as a binder. The molding is fired at 1100 ° C to 1300 ° C, whereby an association of clay and SiO ₂ groups of the silicone resin is achieved.

Another way to describe the US 5,389,325 and the US 5,451,554 , The US 5,389,325 uses phenolic resin as a binder and the US 5,451,554 uses epoxy resin as a binder. In both cases, the resins are cross-linked and cured in a drying step, whereby strength is achieved. However, the applied temperatures are not sufficient to release the activated carbon in the molded article from the added cellulose ether and other thermally destructible aids so that it has an optimum absorption capacity.

The DE 101 04 882 describes systems in which carbonized resin is used as a binder. The DE 101 04 882 discloses a very stable molded article in which the activated carbon particles are embedded in a matrix, the matrix consisting of two interpenetrating three-dimensional structures of a carbonized phenolic resin and an inorganic framework having fired ceramic bonded via a silicate binder.

task The present invention is to provide a molded article having good adsorption properties in which the adsorbent is reliably bound is without the adsorption capacity to significantly limit and that is easy to produce.

The This object is achieved by a molding with at least partially amorphous inorganic support structure and adsorbents dissolved, wherein the adsorbent on and / or in the amorphous inorganic support structure is arranged, wherein the amorphous inorganic support structure Glass is or comprises, the proportion of amorphous inorganic support structure 25 to 60 wt .-%, based on the total weight of the molding is, and wherein the molded body a channel structure with channels having.

preferred Further developments of the molding are in the claims 2 to 19 indicated.

The The object of the invention is further by the use of the molding after one of the claims 1 to 19 as a filter system, preferably in a motor vehicle solved.

Of the Shaped body according to the invention preferably in a filter system, preferably in a filter system a motor vehicle used. The molded body according to the invention is preferably in a tank ventilation system and used in the field of engine air intake of a motor vehicle.

Of the Inventor of the present invention has surprisingly found that a shaped body with good mechanical stability and good adsorption capacity can be obtained when the adsorbent in an at least partially arranged amorphous inorganic support structure, wherein the amorphous inorganic support structure is or comprises glass, the proportion of the amorphous inorganic support structure being from 25 to 60% by weight, based on the total weight of the shaped body, and wherein the shaped body is a channel structure with channels having.

Of the inventive molding can also as adsorptive shaped body be designated. The term adsorptive molding is used in the sense of the invention understood that the molding for Adsorption enabled is. The adsorptive molding can be used, for example, to selectively pollutants, for example, in the form of gases or vapors, to absorb and to at an appropriate time, i. e. to desorb. The so-called regeneration of the adsorptive molding by Desorption can for example take place in that the molding with Flushed with air or nitrogen becomes. The regeneration can also take place, for example, thermally. So can the adsorptive molding also be provided with electrical contacts, which is a controlled Heat of the molding and thus allow a controlled regeneration of the same.

Under The term "amorphous" in the sense of the invention is understood to mean the extensive, preferably complete, absence of crystalline or polycrystalline structures, as for example occur in ceramic material, understood. It means that in the inorganic according to the invention support structure in general no for Crystals typical remote order exists.

Under an amorphous support structure in the sense of the connection, it is understood that the support structure in the essential non-crystalline. The adsorbent (s) are arranged in and / or on the amorphous support structure. Preferably The adsorbents are fixed, so that even with mechanical Load of the molding no or only an insignificant abrasion of adsorbent takes place. The adsorbent or the adsorbent are preferably only partially in the amorphous support structure bound, so that the adsorbent only partially from the amorphous support structure covered or covered are. In other words, the adsorbent is for the most part Part preferably immobilized in or on the amorphous support structure, wherein the biggest part the surface the adsorbent pollutants such as gases or vapors is accessible.

The inorganic amorphous support structure is or includes glass. The inorganic amorphous support structure is neither brittle still porous and thus has the elastic properties of an isotropic solid. These properties allow in particular, a use in motor vehicles, in which the molded body over long periods such as Years of shock is suspended.

The The above and below information in% by weight refers to each the total weight of the adsorptive shaped body, unless otherwise specified , and add up to 100 wt .-% total weight of the adsorptive molding.

Of the Proportion of amorphous support structure is From 25 to 60% by weight, more preferably from 30 to 55% by weight, more preferably 40 to 50 wt .-%, each based on the total weight of the molding.

In an embodiment is the proportion of the glass 25 to 60 wt .-%, more preferably 30 to 55 wt .-%, particularly preferably 40 to 50 wt .-%, each based on the total weight of the molding.

Of the Adsorptive according to the invention moldings includes in addition to the inorganic amorphous support structure further on or several adsorbents and optionally fillers.

For the purposes of the invention, it is understood that a supercooled glass melt is the main reason substance of the amorphous support structure. Therefore, the proportion of the inorganic amorphous support structure in addition to the proportion of adsorbents in relation to other additives optionally used forms the main part.

at an embodiment The glass has a three-dimensional, continuous glass framework structure. Under "three-dimensional, continuous glass framework structure "within the meaning of the invention is a supporting glass structure with or made of glass, which comprises a supercooled glass melt, which forms a solid structure without further binder. The It is surprising to inventors succeeded in an adsorptive molding to provide that due to the three-dimensional continuous Glass framework structure a towering one thermal, chemical and mechanical resistance.

Preferably, the glass comprises supercooled melts of SiO ₂ and additives preferably selected from the group consisting of CaO, Na ₂ O, B ₂ O ₃ , Al ₂ O ₃ , Fe ₂ O ₃ , Na ₂ O, BaO, SrO, PbO , MgO, P ₂ O ₅ and mixtures thereof.

According to one preferred embodiment has the adsorptive shaped body as adsorbent activated carbon, zeolites and mixtures thereof on, preferably particulate available. about the different zeolites, i. the different sizes of the Cage structures can be selectively adjust the adsorption, so for example, a separation of hydrocarbon isomers possible is.

Preferably Activated carbon is used as adsorbent. The proportion of Adsorbent, preferably activated carbon, is preferably in a range of 5 to 50% by weight, more preferably 10 to 40% by weight, particularly preferably 20 to 36 wt .-%, each based on the total weight of the molding.

each commercial Activated carbon can be used in the molding according to the invention become. Preferably, the activated carbon is particulate, but also powdered activated carbon has proved to be suitable in the production of the adsorptive molding. The activated carbon can be natural Sources are obtained. Activated carbons are particularly suitable from charcoal, coconut coal, olive kernel coal, hard coal, lignite coke proved. However, activated carbon can also be made from synthetic materials such as polymeric materials, preferably styrene-divinylbenzene copolymers, optionally sulfonated prior to pyrolysis become.

The Activated carbon, in the molding according to the invention for Is used, is preferably acid activated and / or water vapor activated, to optionally optimize the adsorption kinetics or adsorption capacity.

It has been shown to be particularly activated carbons with an acidic surface make a particularly strong bond with the amorphous support structure.

Further has been shown that at an acidic surface pH <4 too strong Bond between the surface the activated carbon and the supporting structure forms, so that the adsorption behavior are impaired can. The formation of a strong bond between activated carbon with a surface pH <4 probably leads to a stronger one Embedding the activated carbon particles in the amorphous support structure or a stronger one wrapping the activated carbon particles from the amorphous support structure, allowing for adsorption surface available from pollutants decreases or less accessible is. Preferably, the surface of the activated carbon has a pH in a range of 4 to 6.9.

Of the adsorptive shaped bodies contains preferably in addition Fillers. The proportion of fillers is preferably up to 25 wt .-%, more preferably 5 to 18 wt .-%, each based on the total weight of the molding. Preferably contains the molded body at least one filler.

It It has been shown that the use of one or more fillers in the production of the molding according to the invention is advantageous because of this or this one possible Demixing of the starting mixture used in the manufacturing process counteracts or counteracts. When the starting mixture off Glass flour and charcoal particles is composed, has the addition of fillers demonstrated that segregation can be largely avoided. Insofar simplifies the additional Use of fillers the preparation of the shaped body according to the invention. In addition, the filler improves the Dimensional stability, when the supercooled glass melt is melted to produce the amorphous support structure becomes.

Of the filler can also plasticity increase the starting mixture, what happens in the shaping, for example by extrusion can, is beneficial.

When fillers preferably inorganic, in particular mineral fillers in question, especially substances that are good at molten glass tie.

suitable mineral fillers For example, clay, clays, chamotte, kaolin, calcined Kaolin, quartz flour, alumina and highly plastic clay, preferably Ball clay, and mixtures thereof. Ball Clay is a commercially available one Clay with good plasticizing and molding properties (Kentucky-Tennessee company Clay Company of Mayfield, USA). When using materials with a material-related moisture content, such as Clay, it should be noted that when drying the green body of the A shaped body according to the invention higher Drying shrinkage occurs when using materials without moisture content, such as chamotte. materials with plasticizing properties, such as clay, increase the Moldability, for example the ability to extrude, the starting material.

at a further embodiment contains the adsorptive molding Fibers as filler. The addition of fibers advantageously improves the mechanical stability the shaped body according to the invention. The Fibers can thus also be referred to as stabilizing fibers.

The Fibers are preferably inorganic fibers. Preferably Glass fibers or carbon fibers used. In a preferred embodiment is the proportion of fibers 0.1 to 15 wt .-%, preferably 2 to 10 wt .-%, in each case based on the total weight of the molding.

According to one another preferred embodiment contains the molded body to further stabilize the inorganic amorphous support structure and for binding and fixing the adsorbent in addition at least a carbonized resin.

suitable Resins are phenolic resins, furan resins, epoxy resins, polyester resins and mixtures thereof. Preferably, phenolic resin, in particular Novolac, used. Pyrolyzed during the heating or burning of the molding the resin and improves the adhesion between adsorbent and amorphous framework structure. This means, The carbonized resin acts as an additional adhesion promoter.

at according to the invention as a binder preferably used novolak is preferably to a powdered, partially cross-linked phenol-formaldehyde resin, which has a melting point between 80 and 160 ° C, in particular between 100 and 140 ° C, having. According to the invention preferably powdery Novolaks used with high degree of crosslinking because these are the adsorbents little wet and thermally decomposed when heating the green body, so that the surface of the adsorbent is not closed, i. the adsorption properties not or only slightly deteriorated.

According to one preferred embodiment has the adsorptive invention moldings a channel structure on. The channel structure can be continuous and / or non-continuous channels which are rectilinear and / or non-linear, such as wavy, could be. The adsorptive molding is therefore preferably present as a molded body with continuous channels. The channels are preferably straight.

The channels can any geometrically regular and / or irregular, i. general, shape. As a favorable form of a channel cross-section has a geometrically regular shape proved, in particular a tetragonal, preferably square, hexagonal, octagonal and / or circular shape.

Under The shape of a channel cross section becomes the shape of the cross section a single channel, the cross section being vertical to the channel axis. For non-rectilinear channels, the channel axis is non-rectilinear. The shape of the channel cross section of the individual channels will be referred to simply as Designated channel shape.

The inventors have found out that the channel shape has an influence on the flow resistance of the adsorptive shaped body. It has been found that, in a gas through the adsorptive shaped body, depending on the channel shape, regions with different flow velocities training.

The means being dependent from the channel shape a flow resistance established. This flow resistance can be measured by adjusting the pressure of the gas before flowing into the adsorptive shaped body and after outflow from the adsorptive molding records. The pressure drop of the flow is then a measure of the flow resistance in the adsorptive molding.

The Inner wall surfaces the individual channels act as friction surfaces and are significant for the Pressure drop responsible. It turns out that for the same sum the surfaces the channel cross sections, the pressure drop is dependent on the channel shape.

The area The cross-section of a single channel is referred to below as the channel cross-sectional area. The sum of the channel cross-sectional areas will be referred to as open area designated.

Further gets under friction surface the inner wall surface the channel understood. For a circular channel shape, the friction surface is smaller as for all other channel shapes with the same channel cross-sectional area.

At the Flow through a gas through an adsorptive molding with a square Channel shape set in the corners lower flow velocities compared to flow velocities near the canal axis. The stronger the channel shape of a circular Approximate channel shape, the smaller the areas with low flow velocities. A regular hexagonal Channel shape comes a circular Close channel shape, with the regular hexagonal channel shape also the open area optimize and therefore a big one open area can be achieved.

at Comparative measurements have been found to be an adsorptive Moldings, the one regular hexagonal Channel shape compared, a lower flow resistance with an adsorptive molding, which has a square or tetragonal channel shape of the same channel cross-sectional area, Has.

Consequently is the pressure drop in an adsorptive shaped body, the channels with a has a hexagonal channel shape, less than an adsorptive one Moldings, of the channels having a tetragonal channel shape.

at a preferred embodiment Therefore, the adsorptive molded body has a regular hexagonal Channel shape, i. Honeycomb structure, on.

at a further embodiment has the adsorptive shaped body prefers channels with a tetragonal channel cross-section, as such an adsorptive moldings on the conventional Extruders can be made.

Of the Adsorptive according to the invention moldings preferably has a cell density of 10 to 1000, preferably 20 to 600, more preferably 50 to 400 channels per square inch, which preferably extend substantially along the longitudinal axis of the shaped body, on. The molded body usually indicates a cylindrical shape.

Preferably have the channel walls of the adsorptive molding a thickness in the range of 100 μm to 1000 μm, preferably 150 to 450 μm.

• (a) Mischen von Adsorptionsmittel, wenigstens einer eine amorphe Stützstruktur-bildenden Substanz, Plastifizierungsmittel, Flüssigphase sowie gegebenenfalls von weiteren Hilfsstoffen unter Bereitstellen einer formbaren Masse, wobei die amorphe anorganische Stützstruktur-bildende Substanz Glas ist oder umfasst, wobei der Anteil der amorphen anorganischen Stützstruktur 25 bis 60 Gew.-%, bezogen auf das Gesamtgewicht des hergestellten Formkörpers, beträgt,
• (b) Formen der in Schritt (a) erhaltenen Masse zu einem Formkörper, wobei der Formkörper eine Kanalstruktur mit Kanälen aufweist,
• (c) Erhitzen des in Schritt (b) bereitgestellten Formkörpers bis wenigstens zur Schmelztemperatur der die amorphe Stützstruktur-bildenden Substanz,
• (d) Abkühlen des in Schritt (c) erhitzten Formkörpers unter Ausbildung einer amorphen Stützstruktur.

The object on which the invention is based is furthermore achieved by a process for the production of the molding according to the invention, which comprises the following process steps:

• (a) mixing adsorbent, at least one amorphous support structure-forming substance, plasticizer, liquid phase, and optionally other excipients to provide a moldable mass, wherein the amorphous inorganic support structure-forming substance is or comprises glass, wherein the proportion of the amorphous inorganic support structure From 25 to 60% by weight, based on the total weight of the shaped article produced,
• (b) forming the mass obtained in step (a) into a shaped body, the shaped body having a channel structure with channels,
• (c) heating the shaped body provided in step (b) to at least the melting temperature of the amorphous support structure-forming substance,
• (d) cooling the shaped body heated in step (c) to form an amorphous support structure.

preferred embodiments the method according to the invention are in the claims 21 to 45 indicated.

The Shaping in step (b) is preferably carried out by extrusion in step (a) produced starting material.

When liquid phase For example, in step (a), an aqueous phase or water is preferably used. About the added amount of water can adjust the viscosity of the starting mixture become. Preferably the proportion of liquid phase in the provided moldable mass, more preferably the proportion of water in the moldable mass provided, at most 55 wt .-% based on the total weight of the provided moldable Dimensions.

The plasticity the starting mixture is added by adding a plasticizer set. It has been shown that a plasticizer is added must become, to ensure the formability of the mass produced in step (a).

When Support structure-forming Substance becomes a supercooled Glass melt used. Preferably, as a supercooled melt made of crushed glass, preferably glass flour. The inserted glass preferably has a melting point of less than 1200 ° C, on preferably less than 1100 ° C on. A glass that has proved to be very suitable has a melting point in a range of about 900 ° C up to about 1000 ° C having.

For example, the glass may have the composition given in Table 1: TABLE 1 SiO ₂ approx. 63.0% Al ₂ O ₃ approx. 3.0% Fe ₂ O ₃ about 0.1% MgO about 1.2% CaO about 2.0% Na ₂ O about 9.0% BaO approx. 10.0% SrO ₂ about 6.7%

One Glass with the above composition has a softening point of 578 ° C and a melting point of 920 ° C.

Next the adsorbent containing the amorphous support structure-forming substance and plasticizers in step (a) other auxiliaries such as fillers, fibers, lubricants, Soap, green body binder and mixtures thereof are added.

It it has been shown that it is beneficial if in addition to the plasticizer the starting mixture still fillers and / or fibers are added.

In with respect to the fillers and the fibers are referred to the above explanations of the molding, which apply accordingly.

The Plasticizer is preferably selected from the group consisting of from waxes, paraffins, fatty acids preferably oleic acid, and Mixtures of it exists.

These Aids improve the internal lubricity, i. a good lubricity the particles to each other. In particular, be extremely advantageous by a good inner lubricity local jamming effects in the individual channels of the mouthpiece Extrusion avoided.

As well In step (a), a soap may also be added to the starting material be to the sliding of the mass in an extruder or on the tool to improve. A suitable soap preferably comprises core soap, Soft soap or metal soaps. Preferably, sodium stearate or potassium stearate.

Also suitable as lubricating aids are glycerol and / or polyalkylene glycols such as polyethyl proved to be glycols.

at a preferred embodiment in step (a) of the method according to the invention the starting mixture may contain at least one carbonisable resin, preferably a phenolic resin, more preferably a novolak, as a coupling agent be added. The addition of phenolic resin may vary depending on the surface finish in particular the pH of the surface of the adsorbent used depend. If necessary, the addition of an adhesion promoter can be completely dispensed with become.

When further preferred excipient which in step (a) of the method according to the invention may be added, is a green body binder to call. This improves or solidifies the product obtained after extrusion Green body. suitable Green body binder are liquid starch, cellulose ethers or a cellulose derivative, for example methylhydroxypropylcellulose, and mixtures thereof.

Of the Cellulose ether externally binds the water added in step (a) the activated carbon and carries to stabilize the green body. About that promotes out the green body binder also the homogenization of the activated carbon and optionally added fillers existing starting mixture, in which one due to the different Densities, if appropriate, effected separation of the starting materials counteracts.

When Cellulose ethers can for example, methylcellulose, ethylhydroxyethylcellulose, hydroxybutylcellulose, Hydroxybutylmethylcellulose, hydroxyethylcellulose, hydroxymethylcellulose, Hydroxypropylcellulose, methylhydroxypropylcellulose, hydroxyethylmethylcellulose, Sodium carboxymethyl cellulose or mixtures thereof.

Preferably is the amount of added green body binder for example, cellulose ethers, based on the total mass of the starting mixture, not more than about 5% by weight. Otherwise there is a risk that in the heating of the extruded activated carbon article by burning out the green body binder too big Defects in the form of macroporosity arise.

Preferably When adding the water to adjust the viscosity of the Step (a) provided extruded mass up to 20 wt .-% of the water mixed with a portion of the cellulose ether. In this way can advantageously be too strong adsorption of water be avoided in or on the activated carbon.

In Table 2 will give an overview of the preferred ingredients to be used for an extrusion moldable Given mass. The range indications each represent the preferred ones Ranges. It goes without saying possible also to use more or less for the individual components. The respective constituents result for the respective starting mixture Total 100 wt .-% starting mixture. However, the invention is not to the preferred ranges indicated in Table 2 limited.

Table 2

In Step (b) becomes the moldable mass obtained in step (a) Mold, such as an extruder, fed and shaped. After molding, the molding is preferably cut to the desired length. Between molding in step (b) and heating in step (c) For example, a drying step is preferably added to increase the content of liquid phase in the green body, so to lower the green body obtained in step (b) before heating.

The Predrying is preferably carried out by convection drying, microwave drying and / or radiation drying. Preferably, the wet green body is through Irradiation of microwaves with simultaneous flow around with Air pre-dried. In this case, the air preferably has temperatures from about 20 ° C to about 100 ° C, preferably 30 ° C up to 70 ° C. In this way can be the molding according to the invention within from 10 to 20 minutes to a residual moisture content of <5%, without drying that it comes to defects or cracking.

One greater Advantage of the invention produced Green body is, that this one is unusually short Has predrying time. Of course, this is a big simplification of the manufacturing process, since the green body in less time and with less Energy expenditure can be pre-dried.

The Predrying the molding preferably takes place until the remaining content of liquid phase in the shaped body less than about 10% by weight, preferably less than about 5% by weight, each based on the total weight of the molding is.

The Residual moisture can affect the molding advantageously within 40 to 90 minutes in a convection oven be withdrawn, so that the entire drying process about 1 to 1.5 hours drying time.

It It has been shown that it is beneficial if the humidity is permanent and dissipated quickly is going to be a tearing of the extruded molding while to avoid the drying process. Preferably, the shaped body is dried, until the water content is 2.5% by weight or less.

at drying can optionally be a shrinkage of the molding in Diameter and length occur. This shrinkage process depends on the respective components the starting mixture, in particular the proportion of the adsorbent. The shrinkage in the drying step, for example, about 2 to 10%, based on the diameter of the molding, and 1 to 6%, based on the length of the molding, be.

After the optional drying process, step (c) of the process according to the invention preferably involves heating under inert conditions. This heating step comprises, on the one hand, the so-called debindering, ie the thermal decomposition of the auxiliaries used. Preferably, this is Decomposition process under a protective gas atmosphere, preferably under N ₂ atmosphere, carried out to avoid oxidation of the adsorbent.

at the heating in step (c) of the process according to the invention also occurs to a melting of the amorphous support structure-forming substance. Preferably, in step (c), the temperature is maintained at or above Melting temperature of the amorphous support structure-forming substance is held until it is substantially completely, preferably completely, melted is and the adsorbent are fixed to or in the melt. Subsequently, the whole thing is cooled, under solidification of the supercooled melt of glass, the amorphous support structure formed.

at if necessary, it may shrink when heated or burned of the molding in diameter and length come. This shrinkage process depends on the one used Ingredients of the starting mixture, in particular of the proportion of the adsorbent. The shrinkage can after heating or Burning up to 15%, based on the diameter of the molding, and up to 12%, based on the length of the molding, be, wherein the shrinkage involved in the drying step is. Preferably, the total shrinkage after heating or Burning at less than 10%, based on the diameter of the shaped body, and at less than 2%, based on the length of the molding.

The The present invention will be described below by way of examples and with reference to the attached Figures closer explained. The examples serve exclusively the further explanation and are not intended as a limitation to understand.

characters

1 represents a section of an inorganic amorphous support structure ( 1 ) with arranged adsorbent ( 2 ) and fillers ( 3 ).

2 represents a channel cross-section of a square channel shape according to a CFD simulation calculation.

3 represents a channel cross-section of a hexagonal channel shape after a CFD simulation calculation.

4 shows a diagram of an experimental pressure drop measurement.

5 shows a SEM (Scanning Electron Microscopy) recording of the honeycomb body of embodiment 1a.

6 shows a SEM image of pure glass after melting and cooling.

7 shows an SEM image of a ceramic structure of a sintered at 1100 ° C clay.

8th FIG. 4 shows the Wide Angle X-Ray Scattering (WAXS) of the glass frameworks of Embodiments 1a and 1b (AFB 1a and AFB 1b) as compared with a ceramic skeleton structure shown in FIG US 5,914,294 was produced.

Inventive example 1 (example 1)

The adsorbent used was a pulverulent activated carbon having an inner BET surface area of 1560 m ² / g. This activated carbon was activated by means of a chemical process with phosphoric acid and had a pH of 2-3 in an aqueous digest. As the filler clay was chosen to use its plastic properties for the adjustment of the extrusive mass. According to the manufacturer, this clay requires at least 1000 ° C for firing. To prepare the amorphous matrix, the glass indicated in Table 1 was used in the form of glass flour. The glass used had a softening point of 578 ° C and a melting point of 920 ° C. The components were mixed with water and other adjuvants listed in Table 3 according to the proportions by weight indicated.

Table 3

The resulting extrusive Mass was transformed into a cylindrical channel structure using a suitable tool extruded at 200 cpsi (cells per square i).

The Drying was carried out with the help of a circulating air microwave oven. Within of 6 minutes, 95% of the water contained was dried out be formed without recognizable defects on the molding. The remaining 5% of the water contained was in a convection oven at 90 ° C during one Hour withdrawn. While The drying process resulted in a shrinkage of 3.9% in diameter of the molding and 1.5% in length of the molding.

Of the Melting process was carried out in a heating ramp. For this became the dried shaped body under nitrogen atmosphere heated at a heating rate of 5 K / min to 950 ° C and the temperature for 45 Minutes kept. Subsequently was at a cooling rate cooled from 10 K / min to room temperature. There was a shrinkage of 9.1% in the diameter of the molding and 9.1% in the length of the molding Molding.

Of the finished moldings with channel structure had a diameter of 30 mm and was on a length ground of 100 mm.

Several tests were carried out on this finished molded article, which will be described below, in particular also in comparison with the molded articles obtained by the methods described in US 5,914,294 and DE 101 04 882 disclosed were prepared.

stability test

The stability was determined with a simple pressure test. For this purpose, the molding was between two Stamp of a material tensile testing machine (Zwick, 89079 Ulm) clamped, wherein between the molding and the stamps foam rubber for homogenization of the applied compressive forces has been. The pressure was once perpendicular to the channels of the molding and once applied parallel to an axis of the channels of the molding. With a force transducer, the force was determined at which the moldings broke. This value is given in Table 4 as the burst force in N.

Adsorptionskapazitätstest

The adsorption capacity and the ability to re-release the adsorbed hydrocarbons by regeneration with air was determined by a test based on ASTM D 5228-92. The molded article was loaded with n-butane, loading at a concentration of 50% n-butane in nitrogen at a volume flow rate of 0.1 l / min to a breakthrough of 5000 ppm. Subsequently, desorption was carried out with 22 l / min of dry air for 15 minutes. After three adsorption / desorption cycles, a solid working stroke with a residual charge in the adsorptive molding or filter system turned on. The results of this test are given in Table 4 as working capacity in g and residual loading in g given.

Test for effectiveness of filter Systems

Around the effectiveness of the filter system to reduce residual emissions a tank ventilation system To test, the filter system was as an additional filter behind a Activated carbon canister connected. The activated carbon canister was previously in several cycles, while loaded with n-butane and desorbed until an equilibrium state was set. Subsequently was the canister for the emissions test together with the connected filter system defined loaded and once with a total of 294 liters of dry air rinsed. Then there was a 24-hour Compensation phase, in which all the supply lines to the canister and the Filter system were closed. The following was a fuel tank connected and the entire system with fuel tank and connected Activated carbon canister and filter system in a closed climate chamber posed. The output behind the filter was in a so-called Mini-SHED Box (SHED: Sealed Housing for Evaporative Emission Detection) which measured the emissions from the system via the Filters escape, leaving the entire system in 48 hours twice from 18 ° C at 40 ° C was heated up. The measurement was carried out according to the environmental CFR 86 Protection Agency, USA, and in conjunction with the information in the Guideline 24, Release 9 by General Motors. For comparison was the entire test was done without a filter. The results are in mg emissions for each measurement is indicated on the 1st day and 2nd day in Table 4.

Table 4

Result

The values in Table 4 clearly show that the properties of the filter system according to the invention compared to those in the DE 101 04 882 described filter system are significantly improved and compared to that from the US 5,914,294 known filter system are equivalent or slightly improved. In view of the stated procedural advantages, which brings the filter system according to the invention, the present invention represents a significant improvement of the prior art.

Comparative example according to the invention 1a

According to the recipe, which is present in Table 3, further moldings according to the invention were produced, where only the amount of activated carbon was varied and each the water content has been adjusted. The activated carbon component of the embodiment 1 was 36% by weight, the activated carbon components in this comparative example were 20% by weight, 32.5% by weight and 34% by weight. As in Table 5 shown, the activated carbon content between 20 wt .-% and 36 wt .-% surprisingly, it does not affect the shrinkage of the adsorptive molding while the drying and the melting process.

Table 5

Comparative example according to the invention 1b (Vbsp. 1b)

Starting from the recipe in Table 3 and the preparation process described in Example 1 according to the invention, an adsorptive shaped body having an activated carbon content of 18% by weight was prepared. The activated carbon used had an internal surface area of 2000 m ² / g. As in Example 1, the activated carbon was prepared by means of an activation process with phosphoric acid. However, after the chemical activation, water vapor was aftertreated to affect the pore structure. In an aqueous digestion, the activated carbon had a pH of 7. The working capacity corresponded to the values determined in Example 1. The overall shrinkage is, however, significantly reduced.

Inventive example 2 (Example 2)

Starting from the recipe in Table 3 and the production process described in Example 1, an adsorptive shaped body having an activated carbon content of 20% by weight was prepared. The inner surface of the activated carbon used was 1750 m ² / g. The activated carbon was produced by means of a steam activation process. After this activation, the activated carbon in an aqueous digestion had a pH of 9.5. Thereafter, the charcoal was washed with 5% hydrochloric acid after activation and had a pH of 5.9 when used.

f_Red

= Reduktionsfaktor

A_FK

= innere BET-Oberfläche des Formkörpers

Φ_AK

= Aktivkohleanteil im Formkörper

A_Ak

= innere BET-Oberfläche der Aktivkohle

By means of the formula (I), based on the inner surface of the activated carbon used and the weight fraction of the activated carbon, a theoretically expected reduction factor of the finished adsorptive shaped body can be calculated and compared with the shrinkage values determined from the examples. f Red = 1 - A FK / (Φ AK · A ak ) (I) in which

f _red

= Reduction factor

A _FK

= inner BET surface of the molding

Φ _AK

= Activated carbon content in the molding

A _Ak

= inner BET surface of the activated carbon

The Results of the determined shrinkage values and the measured working capacities plotted in Table 6 together with the calculated reduction factors.

Table 6

The Values in Table 6 clearly show that with decreasing pH an increasing shrinkage during the heating step (c) and an increasing impairment the activated carbon occurs.

For the adsorptive shaped body according to the invention in Comparative Example 1b according to the invention, no shrinkage occurs in heating step (c). The amorphous support structure of this shaped body corresponds to the representation as in 1 specified. The amorphous support structure enters into virtually no binding with the activated carbon and hardly seals any outer pores, as can be seen from the theoretical reduction factor.

at the shaped body according to the invention Example 1 made with an activated carbon having an acidic surface became, shows a very good bond between glass and coal.

Inventive example 3 (example 3)

Embodiments 1 and 2 show adsorptive shaped bodies with a regularly tetragonal channel shape. The following example shows the advantages of an adsorptive shaped body having a regular hexagonal channel shape over an adsorptive shaped body having a square channel shape. In 2 and Figure 3 shows the regular hexagonal and square channel shapes respectively.

To illustrate, with the in 2 and 3 CFD (Computational Fluid Dynamics) simulations performed with the program ADINA-F8.0 (see www.adina.com). The dimensions of the theoretical adsorptive shaped article on which the calculation is based have an open area of 78% of the cross-sectional area of the entire adsorptive shaped body and a spacing of the channel walls of 6.52 mm lying in a single channel. For the wall thickness as a variable size, therefore, resulted in a wall thickness of 0.7 mm for the regular hexagonal channel shape and a wall thickness of 0.75 mm for the square channel shape. In the 2 and 3 shown gray levels show the flow velocity within the channels. The shades of gray can be taken from the attached scale.

From a comparison of 2 and 3 It can be seen that in the square channel shape significantly stronger flows form near the channel axis and the cross-sectional area of a single channel is used less than in the regular hexagonal channel shape. The result is a greater pressure drop in the square channel shape compared to the regular hexagonal channel shape. Calculated results from the CFD simulation calculations in the hexagonal channel shape, a 20% lower pressure drop.

• (1) ein adsorptiver Formkörper mit einer regelmäßig hexagonalen Kanalform und den gleichen Abmessungen, die der theoretischen Rechnung zugrunde gelegt wurden (Linie 3 in 4),
• (2) ein adsorptiver Formkörper mit einer quadratischen Kanalform und den gleichen Abmessungen, die der theoretischen Rechnung zugrunde gelegt wurden (Linie 2 in 4), und
• (3) ein adsorptiver Formkörper mit einer quadratischen Kanalform, beidem der Abstand der in einem einzelnen Kanal einander gegenüberliegenden Kanalwände 4,8 mm betrug und eine Wandstärke von 0,55 mm aufwies (Linie 1 in 4). Die Innenkanten der Kanäle wurden zusätzlich durch runde Verstärkungen mit einem Durchmesser von 2 mm unterstützt. Aufgrund der deutlich dünneren Wandstärken wies auch dieser Aktivkohleformkörper eine offene Fläche von 78% der Querschnittsfläche des gesamten Aktivkohleformkörpers auf und besaß somit eine größere Anzahl von Kanälen und demgemäß eine größere Reibungsfläche als die adsorptiven Formkörper (1) und (2).

The theoretical results were checked by experimental measurements. Three adsorptive shaped bodies were measured, each of which had an open area of 78% of the cross-sectional area of the entire adsorptive shaped body:

• (1) an adsorptive shaped body with a regular hexagonal channel shape and the same dimensions as the theoretical calculation (line 3 in 4 )
• (2) an adsorptive shaped article with a square channel shape and the same dimensions as the theoretical calculation (line 2 in 4 ), and
• (3) An adsorptive shaped body having a square channel shape in which the distance of the channel walls opposed to each other in a single channel was 4.8 mm and had a wall thickness of 0.55 mm (line 1 in FIG 4 ). The inner edges of the channels were additionally supported by round reinforcements with a diameter of 2 mm. Because of the significantly thinner wall thicknesses, this activated carbon shaped body also had an open area of 78% of the cross sectional area of the entire activated carbon shaped body and thus had a larger number of channels and consequently a larger friction surface than the adsorptive shaped bodies (US Pat. 1 ) and ( 2 ).

4 shows a diagram in which the pressure drop in Pa as a function of the flow velocity in m / s is plotted for the three adsorptive moldings described above. Out 4 the relationship between channel shape and / or friction surface can be derived. The increase in pressure drop is due to both the channel shape and the friction surface. Out 4 can be estimated that the channel shape contribute to 25% and the friction surface to 75% to increase the pressure drop.

Example 4 (structural investigations)

Additional structural investigations using electron microscopy (SEM) and X-ray wide-angle scattering (WAXS) on molded articles prepared according to Examples 1a and 1b and one according to the prior art ( US 5,914,294 ).

When Scanning Electron Microscope (REM) (Scanning Electron Microscope (SEM)) is called an electron microscope, in which an electron beam in a certain Pattern over the enlarged object to be imaged guided is and interactions of the electrons with the object to produce a picture of the object.

at X-ray scattering it is the scattering of X-rays to matter. she is one of the standard methods for the structure elucidation of condensed matter, especially of crystals. A special form of X-ray scattering is WAXS (Wide Angel X-Ray Scattering, Wide Angle X-Ray Scattering).

5 shows the molding for schematic drawing 1 , Shown is an SEM image of a honeycomb body of embodiment 1a. Activated carbon particles (light gray sharp-edged grains with a size of 10-15 μm) can be seen on the left and right. Below the activated carbon grain on the left side, one can see the smooth amorphous structure of the glass into which the activated carbon grains are embedded. The small grains with 1-2 μm extension are the clay particles, which were used as filler.

The clear difference between the polycrystalline structure of a ceramic lattice and an amorphous matrix is given by the 6 and 7 clear. 6 shows the pure glass after melting and cooling. 7 shows a ceramic structure of a sintered at 1100 ° C clay. The glass has an amorphous smooth surface while the ceramic grid has a rough surface.

In In physics and mineralogy, amorphous material is a substance at the atoms are not ordered structures, but irregular patterns form. Regularly structured Materials are called in contrast, crystals. A polycrystal or polycrystal is a crystal whose crystal structure is irregular. His crystal body consists of many small single crystals (crystallites), the separated by grain boundaries. Most crystals in nature are polycrystalline, but there are also monocrystalline crystals, e.g. Diamonds have an almost perfect monocrystalline shape.

Another proof of the structural difference comes from the examination with the help of X-ray wide-angle scattering. For these investigations, a honeycomb body of the prior art with a ceramic support structure and one honeycomb body of each embodiment 1a and 1b were taken and heated under normal atmosphere to 700 ° C. The activated carbon contained was burned out and left behind are the pure support structures. The honeycomb bodies of the prior art were according to the US 5,914,294 manufactured and have a ceramic structure.

In 8th the WAXS curves of all three support structures are shown. It can be clearly seen that in the exemplary embodiments 1a and 1b, no scattering peaks can be recognized apart from an amorphous background, ie there are no crystalline centers in the structure. The scattering curve of the sample, which according to the US 5,914,294 on the other hand, shows very many peaks, which is due to a very high degree of crystallinity.

Claims (46)

moldings with at least partially amorphous inorganic support structure and adsorbent, wherein the adsorbent on and / or in the amorphous inorganic support structure is arranged, wherein the amorphous inorganic support structure Glass is or comprises, wherein the proportion of the amorphous inorganic support structure 25 to 60 wt .-%, based on the total weight of the molding is, and wherein the molded body a channel structure with channels having. moldings according to claim 1, characterized in that the inorganic amorphous Support structure one is a three-dimensional, continuous glass framework structure. moldings according to one of the preceding claims, characterized in that the proportion of adsorbent 5 to 50 wt .-%, preferably 10 to 40 wt .-%, particularly preferably 20 to 36 wt .-%, each based on the total weight of the molding is. moldings according to one of the preceding claims, characterized in that the proportion of the amorphous support structure 30 to 55 wt .-%, preferably 40 to 50 wt .-%, each based on the total weight of the molding, is. moldings according to one of the preceding claims, characterized that the adsorbent is particulate. moldings according to one of the preceding claims, characterized in that the amorphous support structure additionally at least a filler contains. moldings according to claim 6, characterized in that the proportion of the filler up to 25 wt .-%, preferably 5 to 18 wt .-%, each based on the total weight of the molding, is. moldings according to one of the preceding claims, characterized that the adsorbent is selected from the group consisting of activated carbon, Zeolites and mixtures thereof. moldings according to claim 8, characterized in that the activated carbon Charcoal, Coconut Coal, Olive Core Coal, Hard Coal, Brown Coke Coke and / or polymeric material, preferably styrene-divinylbenzene copolymer is. moldings according to claim 8 or 9, characterized in that the activated carbon acid activated and / or is water vapor activated moldings according to one of the claims 6 to 10, characterized in that the filler is a mineral filler which preferably consists of the group consisting of clay, clays, Chamotte, kaolin, calcined kaolin, quartz powder, alumina and highly plastic clay, preferably ball clay, and mixtures of which is selected becomes. moldings according to one of the claims 6 to 11, characterized in that the filler fibers, preferably inorganic fibers. moldings according to claim 12, characterized in that the proportion of fibers 0.1 to 15 wt .-%, preferably 2 to 10 wt .-%, each based on the total weight of the molding, is. moldings according to claim 12 or 13, characterized in that the fibers Glass and / or carbon fibers are. moldings according to one of the preceding claims, characterized in that the shaped body additionally at least one carbonized Resin, preferably carbonized phenolic resin contains. moldings according to one of the preceding claims, characterized in that the shaped body with a channel structure consistent channels having. moldings according to claim 16, characterized in that the shaped body a Cellularity of 10 to 1000 channels per square inch, preferably substantially along the longitudinal axis of the molding extend, has. moldings according to claim 16 or 17, characterized in that the channels a have tetragonal channel cross-section. moldings according to claim 16 or 17, characterized in that the channels a have hexagonal channel cross-section. Process for producing a shaped article according to a the claims 1 to 19, comprising the following method steps: (a) mixing adsorbent, at least one amorphous support structure-forming substance, Plasticizer, liquid phase as well as possibly further excipients under Provision a moldable mass, wherein the amorphous inorganic support structure-forming Substance glass is or includes, with the proportion of amorphous inorganic support structure 25 to 60 wt .-%, based on the total weight of the produced Molding, is, (B) Forming the mass obtained in step (a) into a shaped body, wherein the molded body a channel structure with channels having, (c) heating that provided in step (b) molding to at least the melting temperature of the amorphous support structure-forming Substance, (d) cooling of the heated in step (c) shaped body to form a amorphous support structure. Method according to claim 20, characterized in that that the liquid phase aqueous or water is. Method according to claim 21, characterized that the proportion of liquid phase in the moldable mass provided in step (a), preferably the proportion of water in the moldable mass provided, at most 55 wt .-% based on the total weight of the provided moldable Mass is. Method according to one of claims 20 to 22, characterized the glass used in step (a) is crushed glass. A method according to claim 23, characterized in that the crushed glass is glass powder or comprises. Method according to one of claims 20 to 24, characterized the glass has a melting point of less than 1200 ° C, preferably less than 1100 ° C, having. Method according to claim 25, characterized in that the glass has a melting point in a range of about 900 ° C to about 1000 ° C. Method according to one of the preceding claims 20 to 26, characterized in that the adsorbent is particulate. Method according to one of the preceding claims 20 to 27, characterized in that the adsorbent from the group, which consists of activated carbon zeolites and mixtures thereof is selected. Method according to Claim 28, characterized that the charcoal consists of charcoal, coconut charcoal, olive-charcoal, Hard coal, lignite coke and / or polymers, preferably styrene-divinylbenzene copolymer is. Method according to one of claims 28 or 29, characterized that the activated carbon acid activates and / or water vapor activated. Method according to one of the preceding claims 20 to 30, characterized in that in step (a) the further auxiliaries from the group consisting of fillers, Slip aids, soap, green body binders and Mixtures thereof is selected become. Method according to claim 31, characterized in that that the filler comprises a mineral filler, preferably of the group consisting of clay, clays, chamotte, Kaolin, calcined kaolin, quartz flour, alumina, highly plastic Clay, preferably ball clay, and mixtures thereof is selected. The method of claim 31 or claim 32, characterized characterized in that the filler Fibers, preferably inorganic fibers. Method according to claim 33, characterized that the fibers are glass and / or carbon fibers. Method according to one of the preceding claims 20 to 34, characterized in that the Plastifizierungshilfsmittel from the group consisting of waxes, paraffins, fatty acids, preferably oleic acid, and Mixtures thereof is selected becomes. Method according to claim 31, characterized in that that the soap is core soap, soft soap or metal soap. Method according to claim 31, characterized in that that the green body binder from the group consisting of liquid starch, cellulose derivatives, such as cellulose ethers and methyl hydroxypropyl cellulose, and mixtures of which is selected becomes. Method according to claim 31, characterized in that that the slip aid glycerol and / or polyalkylene glycols such Polyethylene glycols. Method according to one of the preceding claims 20 to 38, characterized in that in step (a) at least one carbonizable Resin, preferably a phenolic resin, is added. Method according to one of the preceding claims 20 to 39, characterized in that the molding in step (b) by Extrusion takes place. Method according to one of the preceding claims 20 to 40, characterized in that the molded in step (b) shaped body before is pre-dried in the heating in step (c). Method according to claim 41, characterized that predrying by convection drying, microwave drying and / or radiation drying takes place. A method according to claim 41 or 42, characterized that the pre-drying of the molding as long as the remaining content of liquid phase in the shaped body less than about 10% by weight, preferably less than about 5% by weight, each based on the total weight of the molding is. Method according to one of claims 20 to 43, characterized that in step (c) the heating is carried out under inert conditions. Method according to one of claims 20 to 44, characterized that in step (c) the temperature remains at or above the Melting temperature of the amorphous support structure-forming substance is held until it is substantially completely, preferably completely, melted is. Use of a shaped article according to one of claims 1 to 19 in a filter system, preferably a motor vehicle.