Supported catalyst for ozone decomposition.

The invention relates to a supported catalyst for the decomposition of ozone in gases at temperatures below about 50 ° C, to processes for its preparation and method of decomposing ozone by using the polymer foam-supported catalyst.

Ozone, a composite of three oxygen atoms molecule is used in industrial processes and is used for example as a bleaching agent for oils, fibers or paper, for the disinfection of swimming pool water and for purification of technical sewage, it also forms undesirably upon exposure to ionizing or ultraviolet radiation to atmospheric oxygen, for example in the vicinity of electron beam sources, for example in copiers or around mercury-quartz lamps or sunlamps. Further, in nature, for example, in the stratosphere, but also on the ground, in particular in "smog" -Wetterlagen it occurs.

Ozone is highly toxic and very reactive, the ozone content in the exhaust air installations, for example in the exhaust air, which remains after oil refining or in the sterilization of water or sewage should be reduced for environmental reasons if possible. Of course, ozone is in the air, for example, in the stratosphere taken fresh air were for the supply of high-flying aircraft or near ground level at appropriate weather, very problematic for health reasons. The desirable decomposition of the ozone in technical exhaust or breathing air is mainly catalytic. Many metals, particularly platinum group metals, for example palladium or platinum, and metal oxides such as transition metal oxides, have been applied in pure form or as a mixture as the catalytically active component in the catalysts, for example in the form of bulk-supported catalysts for the decomposition of ozone. Very suitable mixed metal oxides, in this connection especially mixtures of manganese dioxide and copper oxide are contained, and have become known as hopcalite. Hopcalites may for example consist of manganese dioxide and copper, but they can also contain further metal oxides, such as nickel oxide, cobalt oxide, silver oxide and, if desired, promoters such as lithium and / or potassium oxide.

Object of the invention was to provide new supported catalysts with advantageous properties for the decomposition of ozone available.

This object is achieved by the inventive supported catalysts.

The supported catalyst according to the invention for the decomposition of ozone in gases at temperatures below about 50 ° C, comprising a support material and a catalytically active component which contains one or more metals and / or one or more metal oxides, is characterized in that the carrier material is a foamed , is substantially open-pored organic polymer which is coated with the catalytically active component.

In principle, all known, foamed, substantially open-pored organic polymers are useful as carriers in the present invention. A variety of such polymers having different properties are known in the art.

For example, can be up to rigid foams used foamed polymers (foam) very different hardness of flexible foams.

The pore size can be in the range of 0.1 to 10 mm, the specific gravity of from 0.005 to 0.05 cm³ g /.

Of critical importance, it is that one uses as a carrier a substantially open-pored organic polymer. Pores are cavities in each polymer. Here are open pores with the surrounding medium connected while closed pores are self-contained and can not penetrate the medium. The term "porous" in the context of the present invention of such pores, which eventually, via openings in the pore wall with other pores and in this way with the surrounding medium, for example air in conjunction.

When flowed through catalyst support material is foamed polymers are of course the better, the higher the proportion of open pores in the polymer. Namely, in the present invention, in principle, also a polymer can be used as a catalyst carrier, which in addition to open pores and has a larger proportion of closed pores and thus is gemischtporig. However, the lower effective surface area and the higher pressure drop can use such a polymer appear as little purpose. In the present invention, therefore, open-porous polymers are essentially as a carrier for the application. The term "substantially open porous" in this context means that a substantial proportion, for example about 90% or more, preferably 95 to about 100%, of the pores contained in the polymer should be open-pored.

It is known that foamed polymers depending on their mode of production closed porous, or porous gemischtporig incurred (according to another notation called these foams also closed cell, mixed cell and open-cell). It is also known that one can optionally convert existing closed pores by chemical or physical methods in open pores. This process is referred to as reticulation. In the present invention, open-pore foamed polymers may equally be used directly in the preparation of substantially open-pored obtained substantially. Similarly, open-pored, foamed polymers can be used substantially, the first closed-incurred or gemischtporig in the preparation and are then reticulated.

A variety of foamed, substantially open-pored polymers of various chemical materials are known to the skilled artisan and may come in the supported catalysts of the invention for application. Well suited are for example polymers based on polystyrene, styrene copolymers, polyvinyl chloride or polyurethane and polychloroprene, because they are particularly resistant to ozone and therefore can also be used for continuous operation.

Very suitable are foamed, substantially open-pored organic polymers based on polyurethane. These are soft Available to rigid foams in form and can be prepared in a conventional manner from isocyanates and water, carboxylic acids, diols, glycol ethers, polyols, and optionally in the presence of propellants, emulsifiers and other auxiliaries.

The catalytically active component is present in the supported catalyst according to the invention expediently in an amount of 5 weight -% to 95 wt%, preferably 20 wt .-% wt to 90, -%, particularly 50 to 90 wt .-%, based on the total weight of the carrier catalyst. If it is present in less than the amounts being surrounded, the Umsetzgrad the ozone decomposition decreases to an insufficient level, it is used in larger than is surrounded quantities, the catalytically active component may not be effectively utilized.

The particle size of the applied catalytically active component should advantageously be in the range of 10 to 500 μ.

As catalytically active component can all metals, especially precious metals such as platinum group metals such as palladium or platinum, and metal oxides, particularly transition metal oxides such as manganese dioxide, cobalt oxide, copper oxide, nickel oxide, are used. It can be a pure metal or mixtures of several metals and / or a metal oxide or a mixture of several metal oxides used. Here, of course, combinations of metals with metal oxides are used.

Preferred supported catalysts according to the invention comprise substantially open-cell, foamed polymers, coated with hopcalite as catalytically active component. Hopcalite are oxide mixtures, calcined at temperatures of 300 ° C and more, which are either of manganese dioxide and copper oxide or a substantial content of manganese dioxide and copper in combination with other oxides, for example, tricobalt tetroxide, silver oxide, nickel oxide, aluminum oxide, cerium oxide, lithium oxide, and / or potassium oxide, Good as catalytically active coating is suitable of the available from the company Kali-Chemie under the name SG 2118 mixed oxide.

Very particularly preferred are supported catalysts according to the invention which have as a carrier material is a polymer based on polyurethane, coated with hopcalite as the catalytically active component, especially preferred are supported catalysts for the decomposition of ozone in gases at temperatures below about 50 ° C, which foamed one, substantially open-pored organic polymer based on polyurethane, coated with hopcalite as the catalytically active component in an amount of 5 to 95 wt, -%, preferably 20 to 90 wt .-%, in particular 50 to 90 wt, -%, based on the total weight of the supported catalyst have.

The supported catalyst according to the invention can in principle be present in any three-dimensional shape, for example, monolith-like. In the form of blocks, plates, mats or balls The volume can range from a few cubic centimeters to several liters, for instance 10 or more liters rich.

The following procedure for the preparation of the supported catalysts according to the invention will be described.

The inventive method for preparation of supported catalysts for the decomposition of ozone in gases at temperatures below about 50 ° C is characterized in that one uses a foamed, substantially open-pored organic polymer as the carrier and this one with one or more metals and / or or more metal oxides coated as a catalytically active component.

In principle, one can in the process for preparing the inventive supported catalysts all known foamed using substantially open-pored organic poly mers, as already described above. Preferably used in the inventive process polymers based on polyurethane, polyvinyl chloride, polystyrene, or polychloroprene. Particularly preferably used in the novel process polymers based on polyurethane as a carrier.

Suitable foams having a pore size of 0.1 to 10 mm, and a density of the foam from 0.005 to 0.05 g / cc are.

Under the following invention can be used foamed polymers of principle any three-dimensional shape. For example, polymers in the form of blocks, plates, mats or balls in any dimension, cc with a volume of a few cubic centimeters, for example 5, to several liters, for instance 10 or more liters are usable.

As catalytically active component, with which the carrier used is coated in the process according to the invention, in principle, all metals or metal oxides known to catalytically decompose ozone, are used. Preferably, the support is coated with a catalytically active component which contains a platinum group metal or a mixture of several platinum group metals, eg platinum and / or palladium and / or a transition metal oxide or a mixture of several transition metal oxides. Particularly preferably the support is coated with mixed transition metal oxides, in particular with Hopcaliten. Hopcalite are metal oxide mixtures, which either consist of manganese dioxide and copper oxide or manganese dioxide and copper, among other oxides, including nickel oxide, cobalt oxide, silver oxide and other metal oxides such as aluminum oxide, cerium oxide, lithium oxide and / or potassium oxide.

Hopcalite various compositions are known to the skilled person by known methods and used as a catalytically active component in the process A very suitable metal oxide is available from Kali-Chemie under the name SG 2118th

The support material may be coated with the catalytically active component according to conventional methods, for example by contacting the carrier with a slurry of the component in water and subsequent drying.

Preferably, the support is coated with a dry, powder form present catalytically active component. The catalytically active component should be present in very finely divided form, for example in particles having a size of 10 to 500 μ, on such particles variables, the catalytically active component can be placed for example in ball mills.

Frequently the coating by contacting the carrier and the active component is possible without any pre-treatment, for example by shaking vibrator in vessels. For example, they are very well suitable for the decomposition of ozone in gases inventive supported catalysts comprising as a foamed, substantially open-pored polymer is a polymer based on polyurethane and as catalytically active component a hopcalite prepared in a simple manner by mixing with the carrier the finely pulverized hopcalite without further pretreatment contacted for coating, for example, in shaking devices, vibrator vessels or rotating drums.

If desired, carriers and / or catalytically active component also undergo a pretreatment to improve the adhesion of the catalytically active component on the surface of the open-pore foamed polymer. For example, you can heat the catalytically active component, for example to temperatures of 150 to 200 ° C, and then brought into contact with the non-pretreated carrier, The heated powder softens the surface of the polymer and consequently liable.

It is also possible to subject the carrier to a pretreatment. For example, you can submit to support a thermal pretreatment, contact the carrier with the surface solvates or solvent (as thin as possible) coated with an adhesive.

In the process for preparing the supported catalyst according to the invention by bringing the catalytically active component in an amount of 5 to 95 wt .-%, preferably 20 to 90 wt, -%, in particular 50 to 90 wt -%, based on the total weight of the supported catalyst, to , If desired, repeat the process of applying such 0ft until the active component is applied in the desired quantity.

In a very particularly preferred embodiment of the method according to the invention is used as carrier is a foamed, substantially open-pored organic polymer based on polyurethane and coated it without pretreatment with a hopcalite in an amount of 5 to 95 wt, -%, preferably 20 to 90 weight .-%, in particular 50 to 90 wt, -%, based on the total weight of the supported catalyst.

Surprisingly, the supported catalysts of the invention proved to be suitable for the decomposition of ozone in gases at temperatures below about 50 ° C. Another object of the invention is a process for the catalytic decomposition of ozone in gases at temperatures below about 50 ° C, passing an ozone containing gas through one of the above-described inventive supported catalysts.

Preferably, the process is for the catalytic decomposition of ozone in gases at temperatures between about 10 and about 25 ° C.

The ozone content of the gas can be up to 2 wt .-%. The method is for instance very suitable for gases with an ozone content in the range of about 0.1 to 1.5 wt .-%.

In the gas to be purified it is preferably ozone-containing air. The relative humidity can be between 0 to about 90%.

Your application will find supported catalysts of the invention for treating the exhaust of technical equipment, for the treatment of breathing air, for the decomposition of ozone in copying machines, in air supply systems of aircraft etc.

The supported catalysts of the invention have surprising advantages. For example, they are at ambient temperature active, they allow an economic utilization of the catalytically active component, they are easy to handle, they are very light, can be cut on site to the desired dimension, are stable to impact or shock and can very easily type are produced.

The following example will further illustrate the invention without limiting its scope.

Embodiment:

<ul><li>1.1 Preparation of the supported catalyst according to the invention. As a carrier, a foamed, open-pored polymer based on polyurethane with a pore size of 0.5 mm and a density of 0.02 g / cm³ was in the form of a block used, the size of the block used were 4 x 4 x 2 cm. As catalytically active component, which is available under the name SG 2118 mixed oxide, a manganese dioxide-copper oxide mixture with binders, the Kali-Chemie was used. The composite oxide, a MangandioxidKupferoxid mixture with binder, was ground μ prior to its use in a ball mill to a particle size of 50 to 100 bar. For coating was allowed without pretreatment of the carrier or catalytically active material the composite oxide with shaking trickle through the pores of the support material, to about 5.3 g of active component per gram of carrier material were applied. The ready-coated carrier catalyst contained 3.4 g of the catalytically active mixed oxide.</li><li>1.2 Application of the supported catalyst according to the invention for the decomposition of ozone The example in 1.1. prepared supported catalyst was introduced into a tubular reactor with gas inlet and gas outlet. Air with a relative humidity of 90% and an ozone content of 16 g per m³ gas was passed at a flow rate of 125 1 / h at ambient temperature (about 25 ° C) by the supported catalyst according to the invention. After passing through the supported catalyst according to the invention, the ozone content in the air was still about 2 g / m³. The degree of conversion amounted to 87%.</li></ul>