A method of producing a catalyst for purification of exhaust gases of technological processes and vehicle exhaust

 

(57) Abstract:

The inventive method of producing a catalyst for purification of exhaust gases of technological processes and vehicle exhaust is that on the metal catalyst carrier are coated with catalytically active material, which is used as ultra-fine powders of oxides of transition metals. The coating is applied by electrophoresis using as electrolyte an aqueous solution of the resin. Thereafter, the catalyst is dried and subjected to heat treatment. 6 C.p. f-crystals.

The invention relates to methods of producing catalysts and can be used for the production of catalysts for purification of exhaust gases and exhaust gases of paint and varnish production, purification from aromatic hydrocarbons chemical industries.

There is a method of preparation of the catalyst, which consists in the fact that the carrier is a honeycomb structure, Panoramico or fiber, then precipitated first 5-30% alkaline-earth or rare-earth metals, then 5-50% of a mixed oxide with the perovskite structure, which is a mixture of rare earth oxides (for example, bespecial sufficient strength, additionally, the difficulty of applying a uniform coverage in hard-to-pore cellular structure is obvious. (Japan, application N 61-242640).

A known method of producing a catalyst for purification of exhaust gases of engines, including the application on the cellular structure of the aluminum oxide layer with the addition of catalytic component (platinum, palladium, rhodium) and an outer layer of aluminum oxide with the addition of 10-60% preventing oslnovani agent (oxides of zinc, calcium, magnesium, barium, sodium, potassium, aluminum, iron, titanium). The last layer is formed of ultrafine powder with a particle size of 50-5000 by dipping method. The use of precious metals in the manufacture of the catalyst leads to a substantial cost, and the application of the last layer by the dipping method does not provide reliable adhesion of the active material with the carrier (Japan, application N 63-252550).

A known method of producing a catalyst for purification of exhaust gases, selected as a prototype, which consists in depositing a layer of catalytically active material on a monolithic carrier. The carrier consists of a rigid substrate coated with a layer of porous material formed of aluminum oxide. The structure rigid subs the data (platinum, palladium, radium, iridi) and base metals, selected from the group which contains Nickel, iron, vanadium, chromium, cerium, tungsten, manganese, tin, germanium, cobalt, uranium, rhenium. The active material is deposited on the carrier sequentially by dipping it in a solution of salts of precious metals a certain concentration, followed by drying and thermal treatment.

The method of preparation of the catalyst involves the successive soaking one end of the carrier in the solution of the first catalytically active material, then the other end in the solution of the second catalytically active material (France, U.S. Pat. N 2622126).

A large number of operations upon receipt of the catalyst is an obstacle to its industrial application. In addition, the use of scarce precious metals leads to a significant appreciation of it. Using this method, it is impossible to achieve a uniform coating layer of the active material along the entire length of the carrier. The pores in the catalyst carrier narrow enough so to cause the active material by this method is difficult because of the rapid depletion of the solution containing the catalytically active material.

The basis of the invention in which, when the selection of catalytically active material and method of applying it to the media would be receiving layer of catalytically active material with highly developed specific surface on a complex shaped surface of the medium due to the high scattering ability of the electrolyte used in the coating process.

The problem is solved in that a method for producing a catalyst for purification of exhaust gases of technological processes, including deposition on the catalyst carrier coating of catalytically active material, followed by drying and heat treatment of the catalyst according to the invention, as the catalytically active material used ultra-fine powders of oxides of transition metals, the application of which to the media, made of metal, carried out by electrophoresis using as electrolyte an aqueous solution of the resin.

High catalytic activity of ultrafine powders of complex oxides of transition and rare earth metals obtained by plasma-chemical method, due to the high dispersion (50-1000 ), large specific surface (15-500 m2/g), neravnovesnuyu to the media by electrophoresis method allows to obtain a uniform thickness and is firmly connected with a base coating layer. Thanks to the good scattering properties of the used electrolyte is provided by the deposition of the active material in hard to reach places and the pores of the support. Moreover, an advantage of the method of electrophoresis is a large deposition rate. The choice of a water-soluble resin as the electrolyte associated with the provision of the scattering ability and opportunity charging of ultrafine powders of complex oxides.

The application of the resin decreases the Flammability of the process, which is important for industrial implementation of the process. In addition, the binder resin is providing good adhesion of the active material to the media, which selected the nanostructural catalyst based on Nickel, Nickel-chromium or copper, with a highly developed surface, a large number of pores and a high gas permeability.

Suitable as catalytically active material to use complex ultra-fine powders of oxides or copper, chromium, manganese and cobalt in the ratio 2:1:1:1, or cobalt, Nickel, manganese and cerium in the ratio 3:3:2:2, or of copper and chromium in the ratio of 1:1. The choice of the composition of ultrafine powders of oxides of transition metals due to their high kata is doctitle to use carboxylic resin. It provides good solubility of the electrolyte in the water. In addition, carboxyl resin has good conductive properties, providing high dispersive capacity of the electrolyte.

To increase the catalytic properties of the active material it is necessary that the particle size of the complex ultrafine powder of oxides of transition metals would be selected in the range of 50-1000 .

To improve the quality and optimising the coating of catalytically active material is the most profitable to make electrophoresis, the electric field would be from 0.3 to 3 V/see

The proposed method of producing a catalyst for purification of exhaust gases of technological processes is as follows.

Make up the solution for the deposition of catalytically active material composed of complex oxide ultrafine powder of transition metals such as Mn, Co, Ni, Ce, Cu, La. The particle size is 50 to 1000 . Owing to their small size particles of oxides have a large specific surface, which provides them with significant catalytic activity.

As the carrier of vibraharpist, good gas permeability, sufficient strength and open porosity. Porosity 95-98% Specific surface area of 10-2m2/g

This object structure provides contact neutralizing gases with a catalyst across its surface. Media degreasing in alkaline with the addition of the cleansing of the drug, then decapitat in a solution of nitric acid.

In the preparation of the electrolyte for the electrophoretic deposition of the active phase of take estimated number of carboxylic resin, neutralized to pH = 8-8,2, then add the required amount of ultra-fine powder of the active oxide. To improve the wettability of the powder add the emulsifier, for example, nonylphenolethoxylates ether. Produce thorough mixing of the suspension with a mechanical stirrer. The suspension obtained is brought to the proper level with distilled water.

The media is placed in the electrolyte and carry out the deposition of the active material by electrophoresis. The deposition of the active phase from the aqueous electrolyte solution is associated with electrochemical processes occurring in the near-electrode space under the action of electric current. Macroion discharged on config discharge ions

R - COO--> CO2+ e + R-R (1)

the electrolysis of water

H2O -> 1/2 O2+ 2H++ 2e (2)

anodic dissolution of metal

Me -> Me+n+ ne (3)

The discharge of ions of the resin is accompanied by the discharge of ionized molecules oxides. The reaction, which determines the formation of precipitates when the electrodeposition is the electrolysis of water (equation 2), and anodic dissolution of metal (equation 3). Resin containing a carboxyl group used in this case, lose their solubility as a result of interaction with hydrogen or metal ions, resulting from the interaction with hydrogen or metal ions electrophoresis is performed according to the mode:

The electric field strength of 0.3 - 3 V/cm Temperature 10-25aboutWith Time 10-35 min

Then the media besieged active material, air-dried and thermoablative at 500 - 800aboutC.

When the electric field is less than 0.3 V/cm deteriorates the quality of the deposited catalytic material and increases the time of his deposition. The increase in electric field intensity higher than 3 V/cm does not improve the quality of the coating of the deposited catalytic material, while

Below are examples confirm the possibility of realization of the proposed method.

P R I m e R 1. Prepare a solution of ultra-fine powder for deposition of active materials by electrophoresis.

Weigh a portion of the powder composition Cu Cr Mn Co in the ratio 2:1:1:1 by weight 70 g dissolved in 50 ml of water. 60 ml of resin dissolved in 100 ml of water. Mix the two solutions, add water to 1 L. the solution is injected 3 g of emulsifier, mix thoroughly.

From the resulting solution lead to the deposition of the active material on the catalyst carrier by electrophoresis on mode:

The electric field strength of 0.3-3 V/cm Temperature 10-25aboutWith Time 15-30 min

After deposition, the catalyst is dried in air and thermoablative at 500-800aboutC for 3 h

P R I m m e R 2. Prepare a solution ultradisperse powder for deposition of active materials by electrophoresis as in example 1.

Weigh a portion of the powder composition Co Ni Mn Ce in the ratio 3:3:2:2 by weight 100 g and dissolve in 100 ml of water, 70 ml of carboxylic resin is dissolved in 100 ml of water. Mix the two solutions, add water to 1 L. the solution is injected 3 g of the emulsifier, in which the gel on mode:

The electric field strength of 0.5-3 V/cm Temperature 10-25aboutWith Time 15-30 min After deposition, the catalyst is dried in air and thermoablative at 500-800aboutC for 3 h

P R I m e R 3. Prepare a solution of ultra-fine powder for deposition of the active material by the method of eletrophoresis analogously to example 1.

Weigh a portion of the powder composition CuCr in a 1:1 ratio by weight of 25 g and dissolve it in 50 ml of water. 10 ml of carboxylic resin is dissolved in 50 ml of water. Mix both solution, made up to 1 liter Injected 1.5 g of emulsifier and carefully mix the solution. From the resulting solution lead to the deposition of the active material on the catalyst carrier by electrophoresis on mode:

The electric field strength of 0.3-2 V/cm Temperature 10-25aboutWith Time 10-20 minutes After deposition, the catalyst is dried in air and thermoablative at 500-800aboutC for 3 h

Thus the invention allows to create a catalyst for purification of exhaust gases without the use of precious metals. The method of applying the active material on the carrier is adaptable and easily implemented in industrial production. Application of the method of electrophoresis psvb the preparation of the CATALYST FOR PURIFICATION of EXHAUST GASES of TECHNOLOGICAL PROCESSES AND VEHICLE EXHAUST including coating the carrier of the catalyst coating of catalytically active material, followed by drying and heat treatment of the catalyst, characterized in that the catalytically active material used ultra-fine powders of oxides of transition metals, the application of which to the media, made of metal, carried out by electrophoresis using as electrolyte a water-soluble resin.

2. The method according to p. 1, characterized in that the catalytically active material used ultrafine powder of oxides of copper, chromium, manganese and cobalt in a weight ratio of 2 : 1 : 1 : 1.

3. The method according to p. 1, characterized in that the catalytically active material used ultrafine powder of oxides of cobalt, Nickel, manganese and cerium in a mass ratio of 3 : 3 : 2 : 2.

4. The method according to p. 1, characterized in that the catalytically active material used ultrafine powder of oxides of copper and chromium in a mass ratio of 1 : 1.

5. The method according to p. 1, characterized in that the electrolyte used is a carboxylic resin.

6. The method according to p. 1, characterized in that the particle is westline electrophoresis, the electric field is from 0.3 to 3 V/see

 

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