Catalyst and method for producing nitrogen from the exhaust gas leakagerough

 

(57) Abstract:

The invention relates to the industrial production of nitrogen, and in particular to a catalyst and method for producing nitrogen from leakagerough exhaust gas. The catalyst for the production of nitrogen from leakagerough exhaust gas containing a metal selected from the group comprising copper, cobalt, iron, chromium, Nickel, manganese and mixtures thereof in the form of oxides and at least one promoter deposited on an inert carrier. While it contains these metals are partially or completely in the form of sulfates formed in the process of contacting the exhaust gas with the specified catalyst in the form of oxides at temperatures up to 500oC in the presence of volatile sulfur compounds, and as a promoter selected platinum group metals. The method of obtaining nitrogen from leakagerough exhaust gas, comprising the stage of contacting the exhaust gas with the catalyst at temperatures up to 500oC and selection of the target product known techniques. As the catalyst using the above catalyst, the reaction is carried out in the presence of volatile sulfur compounds. The use of this invention allows to provide high selectionstyle, more specifically, the catalyst and method of producing nitrogen from leakagerough exhaust gas.

A known catalyst for the oxidation of ammonia containing oxides of base metals as the main catalytically active component and a catalytically active component deposited on made of heat resistant material of the monolithic carrier structure in an amount of 5 to 60% by weight of catalyst, preferably 15 to 25 wt.% (see, for example, an application EP N 0562567 A1, MKI: C 01 B 21/26, 19.09.1993 year).

A known catalyst may also contain cerium, zinc, cadmium or lithium as an impurity, is designed, primarily, to obtain oxides of nitrogen (from admixtures gases). Along with this, the main product in a small amount is also produced nitrogen. Described in the above European patent application way is that immixture gas is subjected to contact with the above catalyst by passing through the catalyst bed at a temperature of 500 to 650oC, followed by separation of the resulting oxides of nitrogen.

The objective of the invention is to develop a catalyst and method for the selective decomposition of ammonia to nitrogen in the am of nitrogen from leakagerough exhaust gas, containing a metal selected from the group comprising copper, cobalt, iron, chromium, Nickel, manganese and mixtures thereof in the form of oxides, and at least one promoter deposited on an inert carrier, and it contains these metals are partially or completely in the form of sulfates formed in the process of contacting the exhaust gas with the specified catalyst in the form of oxides at temperatures up to 500oC in the presence of volatile sulfur compounds, and as a promoter selected platinum group metals.

The proposed catalyst usually contains a catalytically active metal in quantities of 1 to 20 wt.%, and serves as a promoter metal of the platinum group in the number of 100 - 2000 weight. h/mil., supported on a carrier. Suitable carriers include, for example, aluminum oxide, titanium dioxide, silicon dioxide and mixtures thereof.

The proposed catalyst is preferably used in the form of rings, granules, pellets and molded monolithic structure.

The suitable actions to obtain offered of the catalyst include a stage of impregnation of the carrier with an aqueous solution of salts of the catalytically active compounds and promoter and subsequent heating to a temperature up to the defined problem can be solved by the proposed method of obtaining nitrogen from leakagerough exhaust gas, which includes a stage of contacting the exhaust gas with the proposed catalyst at temperatures up to 500oC in the presence of volatile sulfur compounds and selection of the target product by known methods.

The proposed method is typically carried out at a temperature of 200 - 500oC.

As volatile sulfur compounds preferably used sulfur dioxide.

Volatile sulfur compound, which serves to maintain the catalyst in sulfated form or its communication to the desired content of the sulfate is preferably added to amakatarina gas prior to contacting with the catalyst. It may already be contained in the exhaust gas. Volatile sulfur compound is usually used in the amount of 1 - 4000 h/mill. the volume of exhaust gas.

In the proposed method, the exhaust gas containing ammonia at a concentration of up to 10,000 h/mill. , volume, and volatile sulfur compound in the above concentrations are in contact with the proposed catalyst, which is usually placed as a fixed layer in the reactor. When the input temperature between 200 and 500oC, preferably between 230 and 380oC, the decomposition of ammonia to nitrogen according to the following reaction scheme:

4NH3+ 7O2---> 4NO2+ 6H2O,

4NH3+ 5O2---> 4NO + 6H2O,

2NH3+ 2O2---> NO2+ 3H2O.

The invention is illustrated by the following examples.

Example 1

Getting a cobalt-platinum catalyst on a carrier of silica.

Made of silicon dioxide carrier in the form of a ring with an outer diameter of 10 mm is subjected to a calcination at a temperature of 600oC in air flow. Whether therefore the carrier is impregnated with an aqueous solution of cobalt nitrate to the final concentration of cobalt, equal to 10% by weight of the impregnated carrier. The impregnated carrier is dried and then impregnated with an aqueous solution hexachloroplatinum acid to the final concentration of platinum equal to 670 h/mill. in terms of the weight of the impregnated carrier. In conclusion, the impregnated carrier is dried and calicivirus at a temperature of 500oC air flow in order to obtain the ready-to-use catalyst.

Example 2

Repeat example 1 with the only difference that prepare the catalyst on a carrier of silica, which contains 10 wt.% copper and 6 is s ' solution of nitrate of copper and then with an aqueous solution hexachloroplatinic acid. Thus obtained impregnated carrier calicivirus described in example 1.

Example 3

Obtaining a catalyst on a carrier of silica, containing copper, Nickel and platinum as the active component.

The catalyst is prepared as described in example 2, by the way, with the only difference that before impregnation with platinum media impregnated with another aqueous solution of Nickel nitrate to a final concentration of Nickel equal to 10 wt.%.

Example 4

Obtaining a catalyst on a carrier of silica, containing copper, palladium and platinum as the active component.

Whether the above image carrier of silica impregnated with an aqueous solution of copper nitrate to the final concentration of copper equal to 10 wt.%. Soaked so the carrier is dried and then impregnated with an aqueous solution of palladium nitrate and hexachloroplatinic acid to the concentration of palladium and platinum, component 670 h/mil., in terms of the weight of the impregnated carrier. Thus obtained catalyst is activated by calcination at a temperature of 500oC in air flow.

Example 5

Obtained in examples 1 - 4 catalysts adiabatic tubular reactor mode serves to 0.25 l of each catalyst, placed as a fixed layer. Then passed through the reactor gas containing 20 volume. % oxygen, 2 vol.% water, 1000 h/mill. ammonia and up to 200 h/mill. sulphur dioxide. The process is carried out in specified in the following table conditions. This table also summarizes data for ammonia conversion and selectivity of the formation of nitrogen achieved these catalysts under these conditions.

According to table it can be seen that the decomposition of ammonia to nitrogen significantly improved in the presence of a small amount of sulfur dioxide added to the source gas at the reactor inlet. Sulfur dioxide provides the conversion of the oxides catalytically active metals to sulfates. Desulfation catalysts do not provide high selectivity towards the formation of nitrogen during decomposition of ammonia. The formation of harmful nitrogen oxides largely prevented.

1. The catalyst for the production of nitrogen from leakagerough exhaust gas containing a metal selected from the group comprising copper, cobalt, iron, chromium, Nickel, manganese and mixtures thereof in the form of oxides, and at least one promoter deposited on an inert carrier, characterized in that it contains these metals Chim catalyst in the form of oxides at temperatures up to 500oC in the presence of volatile sulfur compounds, and as a promoter selected platinum group metals.

2. The catalyst p. 1, characterized in that the platinum group metals include platinum and/or palladium.

3. The catalyst p. 1, characterized in that it contains the specified metal in quantities of 1 to 20 wt.%.

4. The catalyst p. 1, characterized in that it contains a promoter in the number of 100 - 2000 weight.h./mill.

5. The method of obtaining nitrogen from leakagerough exhaust gas, comprising the stage of contacting the exhaust gas with the catalyst at temperatures up to 500oC and selection of the target product by known methods, wherein as the catalyst use of catalyst for PP.1 to 4, wherein the reaction is carried out in the presence of volatile sulfur compounds.

6. The method according to p. 5, wherein amakatarina exhaust gas add volatile sulfur compound.

7. The method according to p. 5, characterized in that use volatile sulfur compound in the amount of 1 - 4000 h/mill. the volume of exhaust gas.

8. The method according to p. 5, characterized in that as volatile sulfur compounds using sulfur dioxide.

 

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13 cl, 1 tbl, 4 ex

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