WO2008128698A1 - Method for equipping a preferably porous ceramic carrier material with an active substance - Google Patents

Abstract

The present invention relates to a method for impregnating a porous ceramic carrier material with an active substance, which is used, for example, as a catalyst, fungicide, bleaching agent, adsorption agent, or the like. The finely ground carrier material is dry ground together with an active substance salt. A dry additive separating the active substance based on an aldehyde-containing power is added to the powder mixture thus obtained while continuing to grind.

Description

 Process for finishing a preferably porous ceramic carrier material with an active ingredient

Description:

The invention relates to a process for finishing or impregnating a preferably porous ceramic support material with an active ingredient which is used, for example, as a catalyst, antibacterial substance, fungicide, bleach, adsorbent, fragrance or odorant, insect or pollutant thickener, etc. - The equipment or impregnation of the optionally porous or non-porous ceramic support material comprises in particular a loading, a modification, an attachment, a storage, etc. of the drug in question to or in the relevant ceramic support material.

Such methods are known in principle, for which reference should be made, for example, to WO 2006/094729 A1. This relates to the production of a catalytically active mineral based on a framework silicate for use as a catalyst base material in catalytic exhaust gas purification in particular automobiles. For this purpose, the framework silicate is first treated with a metal salt solution and then dried. The dried framework silicate in the hydrogen form is treated with a transition metal based metal salt in the course of solid-state ion exchange. The skeletal silicate used is predominantly a natural mineral, for example zeolite.

In addition, DE 40 36 298 C2 discloses an antibacterial ceramic material. As a ceramic material, the document recommends, among others, calcium hydrogen phosphate, calcium carbonate, calcium silicate or zeolite. The active substance adsorbs an aqueous metal salt, wherein additionally a firing or a heat treatment is carried out. In the event of of zeolite presents a disadvantage that the carrier material concerned must undergo various steps and chemical reactions for the equipment with the active substance. In addition, it is necessary, for example, to pretreat natural zeolite in order to clean its pores and to prepare the surface for the attachment of the active substance.

Quite apart from this, so-called nanostructured metal preparations, in particular silver preparations, which are prepared by wet-chemical exchange by ion exchange, are known in practice. In general, a calcining reduction of silver salts with ammonia takes place. Although these procedures have proven themselves, they are technologically complex and consequently cost-intensive. In addition, the catalytic effect of the carrier material impregnated in this way, for example, can only be predicted relatively inaccurately, because the described process can not be described quantitatively in quantitative terms. In addition, such modifications must be made in complex reactors. In addition, by-products and waste products are formed, which must be removed and disposed of with the help of cumbersome washing or cleaning processes from the generated reaction mixture. Consequently, the previous approach requires the additional use of energy for drying and grinding operations. This is where the invention starts.

The invention is based on the technical problem of specifying a method for finishing or impregnating a ceramic carrier material with an active substance which requires little effort, is simple, inexpensive and environmentally friendly and in particular produces no or little waste.

To solve this technical problem, the invention provides a process for finishing or impregnating a ceramic support material with an active ingredient which is used, for example, as a catalyst, fungicide, bleach, adsorbent, antibacterial substance, odorant, insecticide or pollutant, etc. after which finely ground support material is dry-ground together with an active substance salt, and after which the powder mixture thus obtained is added to a drug-releasing dry additive based on an aldehyde-containing powder with continued grinding.

The ceramic carrier material is preferably a porous ceramic carrier material, although in principle non-porous ceramic carrier materials may also be used. In addition, the grinding process is carried out tribo-mechanically, d. H. especially rubbing and not beating. Here are preferably counterfeiting proven.

In the context of the invention, the dry matter in question based on the aldehyde-containing powder is advantageously added together with a basic solution of the powder mixture of the carrier material and the active ingredient salt. The basic solution is advantageously the solution of a nitrogen compound in water, for example an ammonium hydroxide solution. This solution generally has a weakly corrosive effect, especially since the proportion of the ammonium hydroxide in the solvent is about 20% by weight to 30% by weight. As a solvent, the invention generally recommends recourse to water.

The basic solution primarily ensures that the porous ceramic carrier material undergoes a cleaning before and during the impregnation process, in particular that the cavities present in the carrier material are not closed by, for example, soiling and / or naturally occurring exchangeable components. Incidentally, the basic solution in question often favors the removal of the active ingredient from the active substance salt with the aid of the dry additive.

In fact, it has proved to be particularly favorable if a metal is used as active substance and a metal salt as active substance salt. It can be used as metals precious metals such as silver, gold or platinum, or (other) transition metals such as chromium, manganese, iron, copper, nickel, tin etc. In the cases described, the active substance salt or metal salt is then present as noble metal salt or transition metal salt. Also, the use of semi-metals such as selenium or silicon is conceivable and is encompassed by the invention. Consequently, the active substance salt or metal salt is consequently a semi-metal salt.

If selenium is used as the active ingredient, the porous ceramic carrier material is used to release mostly elemental selenium, which is used for supplementation or as a feed or fertilizer additive. On the other hand, if silver is used as the active ingredient, then its antibacterial effect or its action as a fungicide is primarily in the foreground. Copper also has an antibacterial effect or it is possible to use copper as the active ingredient or catalyst or fungicide when using the impregnated ceramic support material according to the invention.

With regard to the other metals described, their catalytic action or their ability to act as adsorbents are primarily determined. As a rule, the dry substance ensures that the active substance in question is eliminated in elemental form. In other words, in the case of, for example, silver as nano-dispersed active substance, ie active ingredient whose deposited active ingredient parts are in the nanometer range, it is achieved with the aid of the dry substance that elemental silver or silver complexes on the surface of the porous ceramic carrier material or in its cavities To be available.

As a porous or non-porous ceramic support material is generally a tectosilicate (clay) or skeleton silicate used and here preferably a zeolite. Both natural and synthetic zeolites can be used. In addition, swelling clays can be used depending on the application. In fact, the invention recommends recourse to clinopthiolith as well as chabazite, mortenite or mixtures thereof. It has proven useful if the framework silicate used at least 50 wt .-% of contains natural zeolite, the remainder can be formed, for example, of artificial zeolites. The natural zeolite used in turn contains more than 50% by weight, preferably more than 70% by weight, of clinopthiolite.

The specific surface of the Klinopthioliths initially has a size in the range of 10 to 90 m ² / g. After the addition of the active substance, the size of the specific surface area is in the range from 10 to 350 m ² / g, depending on the amount of active substance and, if appropriate, additionally occurring or taken place thermal treatment. The cation exchange capacity remains the same before and after the addition of the active substance and is in the range of 0.8 to 2.0 milliequivalent (meq) / g. Loading with silver does not change the crystal structure of the original ceramic support material, especially the zeolite. On the basis of the parameters and the measured values found, it can be seen that the intrinsic properties of the zeolite have not changed or have not been lost or masked by the addition or storage of active ingredient. The accumulated or stored amount of active ingredient can be easily varied overall, in the range of a few ppm to even a few percent by weight.

In detail, the carrier material is present in a fineness, which corresponds to grain sizes in the submillimeter range, for example, is located below 500 microns. The same applies to the active substance salt and the added dry matter. It has proven useful if the carrier material and the active salt and the dry additive are ground together in a mill, in which case preferably a pug mill is used. - In particular, the grinding process is continued in the sum for a period of 30 minutes, in particular more than 60 minutes, and preferably between 80 and 180 minutes.

As a dry additive, the invention recommends an aldehyde-containing powder which has a reducing effect. In this case, sugar, especially glucose, has proven to be particularly favorable. In fact, the glucose of grape sugar becomes attached an aldehyde function, so it acts like dehydrated alcohol, that is, an alcohol, was removed from the hydrogen. Consequently, aldehydes are particularly reactive and have a reducing action in the present case. For the positive partial charge of the carbonyl carbon atom in the aldehyde group (CHO) causes an electron deficiency at the adjacent carbon atom. If this carries a hydrogen atom, it can easily be released as proton (H ⁺ ) and react reducingly with oxygen atoms.

If, in the example, the active substance is silver and the active salt used is a silver salt, in particular silver nitrate (AgNOs), the silver salt in question is reduced by the dry additive or glucose and elemental silver particles are formed on the surface of the porous ceramic carrier material, which provide the desired antimicrobial effect in the example case.

It has proven to be altogether good if the active substance salt and the dry additive are mixed together in a weight ratio of 0.8: 1 to 1: 1, 5. For the mixing ratio between the active substance salt and the basic solution, the invention recommends a weight ratio in the sense of 1: 3.0 to 1: 5.0. As a result, a total of no (toxic) waste is observed, but rather the carrier material is ultimately loaded with the desired active substance or impregnated by the drug in the elemental form or as an active ingredient complex via the detour of the active ingredient salt and its reduction at the end of the process. The individual constituents or particles of the active ingredient usually take sizes in the nanometer range, ie. h., That the active ingredient is in nano-dispersed form.

Example: Finely ground natural zeolite having a grain size below 1 mm is mixed with a silver salt, in particular silver nitrate. The silver salt or silver nitrate is finely distributed on the surface of the porous ceramic support material by hollows and is also - at least after grinding - in a particle size of less than 1 mm. For this purpose, both mixture components are filled into a corresponding pug mill. In this process, moreover, large portions of the drug salt or silver salt are pressed into the cavities of the carrier material by the Kollervorgang.

This fine powder mixture is then added to the dry additive, which is an aldehydgruppenhaltiges powder. Its grain size is less than 1 mm. In the exemplary embodiment, grape sugar in food quality is used. The mixture of the dry additive, the porous ceramic support material and the active ingredient or the active ingredient salt is then ground again in the muller run until the individual mixture components are evenly distributed.

Subsequently, the basic solution is added to this dry powder mixture. In this case, an ammonium hydroxide solution with an ammonium content in water of about 25 wt .-% is used. The individual constituents of the mixture are present in the following weight ratio: silver nitrate to glucose and the 25% strength ammonium hydroxide solution in the ratio 1: 1, 2: 4.0.

The grinding process is continued over a period of 60 minutes to 180 minutes taking into account this recipe. For the most part, the silver salt or silver nitrate is converted into nano-dispersed metallic elemental silver. In this context, a reduction of the respective silver cation by the dry additive or glucose in the example takes place. In any case, at the end of the process, an elemental silver-coated support material or zeolite is available, which can be used directly as an example antibacterial substance or, for example, as a stain or bleach in combination with washing substances. Overall, the described method achieves the particular advantage that almost 100% by weight of the at least one active substance or of the several active substances is practically lossless in contrast to a liquid ion exchange on or in the carrier material are stored. In comparison to a solid-state ion exchange, the process described allows the addition of the active ingredient even at room temperature. Furthermore, the method described has the advantage that in only one method step it is possible, under certain circumstances, to accumulate or store various active or desired active substances, to be precise in the amount prescribed and required by the particular application.

In contrast to customary ion exchange processes, the invention offers the option of mainly very strongly (to the nanometer scale) dispersed components of, for example, metallic or metalloxidischen active ingredients. Due to this scaling of the active ingredients in the nanometer range, there are particularly positive effects for the described applications of the thus treated carrier material or its active ingredient as a catalyst, fungicide, bleach, adsorbent etc ..

In fact, the nano-dispersed active substances or the resulting nanostructures are not washable and also not exchangeable and thus differ significantly from other loaded carrier materials in which ion-exchanged components can be removed. As a result, a constant loss of the active ingredients is observed and also an increasing toxicity of the carrier material or in the application. Here are the main benefits.

Claims

claims: 1. A process for finishing a preferably porous ceramic support material with an active ingredient, which is used, for example, as a catalyst, fungicide, bleach, adsorbent, etc., after which the finely ground support material is ground dry together with an active salt, and then the powder mixture thus obtained a the active ingredient releasing dry additive based on an aldehyde-containing powder with continued, in particular tribo-mechanical, grinding is added. 2. The method according to claim 1, characterized in that the dry additive based on the aldehyde-containing powder is added together with a basic solution of the powder mixture. 3. The method according to claim 2, characterized in that as solvent for the basic solution of water is used. 4. The method according to any one of claims 1 to 3, characterized in that the active ingredient is a metal and used as an active salt, a metal salt. 5. The method according to any one of claims 1 to 4, characterized in that the dry additive splits off the active ingredient in elemental form. 6. The method according to any one of claims 1 to 5, characterized in that a tectosilicate, in particular zeolite, is used as a porous ceramic support material. 7. The method according to any one of claims 1 to 6, characterized in that the carrier material and the active ingredient salt and the dry additive in a mill, preferably a pug mill are ground. 8. The method according to claim 7, characterized in that the grinding process in the sum of more than 30 minutes, in particular more than 60 minutes and preferably between 60 minutes and 180 minutes is continued. 9. The method according to any one of claims 1 to 8, characterized in that is used as dry additive sugar, especially glucose, use. 10. The method according to any one of claims 1 to 9, characterized in that the active substance salt and the dry additive in a weight ratio of 0.8: 1 to 1: 1, 5 are mixed together. 11. The method according to any one of claims 1 to 10, characterized in that the active substance salt and the basic solution in a weight ratio 1: 3.0 to 1: 5.0 are mixed together.