JPH0768178A - Catalyst body for removing particulate substance in diesel vehicle and preparation thereof - Google Patents

Abstract

PURPOSE: To provide a catalyst for removing particulate material from diesel engines, its manufacturing method and a method removing the particulate material from the diesel engine by using it. CONSTITUTION: A catalyst is constituted by impregnating a impregnating support manufactured from alumina containing alminumphosphate or a phosphor on a surface of filter media and impregnating at least one noble metal selected from among platinum, rhodium, and palladium. As the impregnating support alumina containing aluminumphosphate or a phosphor is manufactured and is impregnated in filter media. A manufacturing process comprises a step for supporting a platinum group solution to the manufactured filter media and a step for subjecting generated products to high temperature heat treatment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst body for removing particulate matter in exhaust gas discharged from a diesel vehicle, a method for producing the same, and a method for removing particulate matter using this catalyst body. Is.

[0002]

2. Description of the Related Art Particulate matter emitted as exhaust gas from diesel vehicles is unburned carbon particles having an average diameter of about 0.3 μm, and the ownership ratio of diesel vehicles is 42% of all vehicles.
%, Which is higher than other countries in the world, is emerging as a major cause of air pollution, and the concentration of particulate matter has exceeded the environmental standard value (smog regulation value for heavy duty vehicles in 1993: 40%). If it exceeds, it causes severe visual discomfort and causes harmful diseases such as cancer to the human body. Therefore, strict emission regulations for such particulate matter are required. In the case of heavy duty diesel vehicles, the Republic of Korea was
67g / HP.Hour, 0.1g / H since 1994 in the US
Since P.Hour is in the trend of tightening regulations, research to remove particulate matter emitted from diesel vehicles is actively under way to satisfy this. The development direction of particulate matter removal technology includes suppression of unburned material generation by improving engine efficiency, improvement of combustion performance using a fuel additive, and post-treatment technology of particulate matter.

The method of improving the efficiency of the engine and using the fuel additive can increase the combustion effect in the engine and fundamentally reduce the harmful substances such as particulate matter or soot, but are excessively expensive. However, in the current state of the art, it is not easy to completely suppress it, and in the end it is actually emitted through exhaust gas. The post-treatment technology is composed of a filtration technology that filters particulate matter in exhaust gas and a regeneration technology that burns the filtered particulate matter to regenerate the filter material. Research is being conducted on selection of filter media with excellent performance that can be effectively collected and application to actual vehicles.

However, the filtration of particulate matter causes damage to the filter medium due to an increase in the back pressure in the engine exhaust passage and induces a deterioration in engine performance. Since the filter material is subjected to thermal shock, the durability problem is serious. Therefore, it was necessary to develop a regeneration technique for effectively burning the particulate matter at a low temperature. The most widely known regeneration technology to date is to supply secondary energy using a burner, heater, etc. or to raise exhaust gas temperature by throat ring to regenerate, and to add catalyst to fuel or filter catalyst. There is a method in which the activation energy of the oxidation reaction is reduced by adhering it to the material to regenerate it. In particular, among these regeneration techniques, a catalytic method has been studied as a method for removing particulate matter. This is a ceramic foam, on the top surface of which is deposited a catalytic material capable of burning particulate matter,
Traps that contain refractory three-dimensional structures such as wire mesh, metal foam, Willflow ceramic honeycombs, open flow ceramic honeycombs or metal honeycombs are used to trap fines in the exhaust gas of diesel engines, usually It is constituted by burning particulate matter under exhaust conditions (gas composition and temperature) of exhaust gas under the operating conditions of the diesel engine.

The performance generally required as a catalyst for purifying exhaust gas of a diesel engine is as follows. (1) Not only fine carbon particles but also harmful components such as unburned hydrocarbons can be removed with high efficiency by combustion even at low temperature. (2) The activity of converting SO ₂ derived from a sulfur component contained in a large amount in light oil used as a fuel into SO ₃ should be lowered to reduce the emission of SO ₃ which is fatal to the human body. First, it is possible to prevent a sudden decrease in catalyst activity due to SO ₃ . (3) High durability to withstand continuous operation even at high temperatures. By the way, the technique varies depending on the physical and chemical properties such as the type and amount of the catalyst used and the surface area of the catalyst component. Until now, there have been various proposals for improving the efficiency of particulate matter removal by combustion. These conventional methods uniformly support a platinum group metal, which is known as a catalyst for burning particulate matter, and pre-infiltrate a filter medium with an infiltration support such as activated alumina or titania in order to provide a large reaction surface area. Then, a method of supporting the filter medium with a solution of a platinum group salt has been used.

[0006]

However, the above method does not always give a satisfactory catalytic effect. That is, the normal alumina has thermal stability even at a high temperature of about 800 ° C. and has sufficient durability for continuous operation at a high temperature, but is discharged by combustion of a sulfur component contained in a large amount in light oil. While reacting with sulfur trioxide, which is converted into aluminum sulfate, the surface area decreases and the pore structure changes, so that the activity of the catalyst using alumina as a carrier drops sharply.

Further, the above-mentioned ordinary titania is chemically stable with respect to such sulfur trioxide and there is no activity decrease due to sulfur trioxide, but it is thermally unstable above 500 ° C. 300 to 6 which are the driving conditions for diesel vehicles
Deteriorated at an exhaust gas temperature of around 00 ° C, especially when burning soot,
In other words, if the trap is repeatedly exposed to a rapid temperature rise during regeneration, the activity and durability will decrease due to the decrease in the surface area of titania and the destruction of the pore structure due to the phase change (change from anatase form to crystalline rutile form). .

Therefore, an object of the present invention is to provide a catalyst body which is thermally stable at high temperature and maintains a high catalytic effect for a long period of time and does not have a decrease in catalytic activity due to sulfur oxides generated after diesel combustion. is there. Another object of the present invention is to provide a method for producing a catalyst body for removing particulate matter of a diesel engine using the above-prepared deposition support. Yet another object of the present invention is to provide a method for removing particulate matter of a diesel vehicle using the produced catalyst body.

[0009]

As a result of several experiments and studies, the present inventor has dispersed at least one platinum group metal selected from platinum, palladium and rhodium in aluminum phosphate or phosphorus-containing alumina, The fact that supported catalyst bodies can significantly improve the thermal stability at high temperatures and the chemical stability towards sulfur trioxide compared to existing catalyst bodies produced with alumina or titania as the impregnated support The present invention has been completed based on the findings. In order to achieve the above object, the catalyst body for removing particulate matter of a diesel vehicle according to the present invention comprises a filter medium, a permeation support made of aluminum phosphate or phosphorus-containing alumina, which is adhered to the surface of the filtration medium, and a platinum support on the permeation support. , At least one noble metal selected from rhodium and palladium is deposited.

The method for producing a particulate matter removing catalyst body for a diesel vehicle according to the present invention for achieving the above-mentioned other objects, comprises:
a) producing alumina containing aluminum phosphate or phosphorous as an adherent support, and b) above a).
The step of soaking the support in the filter medium; c) supporting the platinum group solution on the filter medium soaked in step b); and d) heating the product of step c) to high temperature. A heat treatment step. The removal method of the present invention to achieve the still another object is to remove particulate matter of a diesel vehicle using the catalyst body or the catalyst body produced by the method. Hereinafter, the present invention will be described in more detail as follows.

The surface of the filter material of the catalyst for removing particulate matter of the diesel vehicle of the present invention is infiltrated with the infiltrated support made of aluminum phosphate or phosphorus-containing alumina, and platinum, rhodium or palladium is deposited thereon. Obtained by depositing at least one noble metal selected from The method for producing a catalyst body for removing particulate matter of a diesel vehicle according to the present invention comprises producing aluminum phosphate or phosphorus-containing alumina as an adsorbent support, adhering the adsorbent support to a filter medium, and the filter medium Is supported by a platinum group solution, and the product is heat-treated at a high temperature. In the present invention, aluminum phosphate and phosphorus-containing alumina are used as substances that adhere to the filter medium to support the catalyst.

Aluminum phosphate is produced by reacting aluminum nitrate and ammonium phosphate in an aqueous solution. Specifically, the aluminum nitrate aqueous solution and ammonium phosphate are adjusted so that the weight ratio of phosphorus to aluminum is preferably 0.5 to 1.5. An aqueous solution of fate is prepared, and the two solutions are mixed, and then concentrated aqueous ammonia is added to adjust the pH to 7-9. The hydrogel thus produced is dried and then heat-treated at a temperature of 500 ° C. or higher to manufacture it. The heat treatment temperature is 800 to 9 as required.
It is possible to use 00 ° C., and there is no particular limitation.

The phosphorus-containing alumina is produced by mixing alumina and an aqueous solution of phosphoric acid, and specifically, has a specific surface area of 1 m ² / g.
The above alumina, preferably 10 m ² / g or more of alumina, and 0.001 / 1 based on alumina.
The mixture is mixed with an aqueous solution containing 0.1 to 30 wt% of phosphoric acid, that is, containing 0.1 to 30 wt% of phosphoric acid. It is dried and then heat-treated at 500 ° C. or higher to fix phosphorus in the form of aluminum phosphate, thereby producing. The heat treatment temperature is 800 to 900 as required.
It is possible even at ° C, and there is no special limitation. When the weight ratio of phosphoric acid to alumina is less than 0.001, the concentration of phosphorus to alumina is too low to prevent the oxidation reaction of sulfur sufficiently, and the weight ratio of phosphoric acid to alumina is 0.1.
When it is 3/1 or more, phosphorus itself acts as a catalyst poison that reduces the catalytic activity of alumina.

The filtering material used in the present invention is a particle of diesel such as ceramic foam, ceramic fiber filter, open flow ceramic honeycomb, will flow honeycomb monolith, open flow metal honeycomb, metal foam or metal mesh. All three-dimensional structures already known, which are useful for the filtration of particulate matter, can be used, without any particular restrictions.

It is desirable that the permeation support used in the present invention permeate 5 to 200 g per liter based on the above-mentioned filter material. If it is 5 g or less, a sufficient surface area cannot be provided and the catalytic effect is lowered, and if it is 200 g or more, the pressure of the exhaust gas is excessively increased to lower the efficiency.

The platinum group metal used in the present invention is at least one platinum group metal solution selected from platinum group metal compounds such as platinum, rhodium and palladium, and the content of platinum, rhodium and palladium is 1 L of the filter medium. It is preferably 0 to 6 g, 0 to 6 g, and 0 to 3 g, respectively.
Further, the ratio of the amount of at least one noble metal selected from platinum, rhodium and palladium to the adhesion support (precious metal / adhesion support weight ratio) is 0.001 / 1 to 0.2 /.
A range of 1 is desirable. The filter medium carrying the platinum group metal solution is heated, for example, at a temperature of 500 to 600 ° C. to finally obtain a catalyst body in the form of metal or metal oxide.

[0017]

EXAMPLES The constitution of the present invention will be specifically described below based on examples. However, this example does not limit the scope of the present invention. Example 1 Sample manufacturing method 1. Production of Aluminum Phosphate 4.9 kg of aluminum nitrate and 3.3 kg of ammonium phosphate were dissolved in 5.7 L of water, respectively, and the two solutions were mixed with each other, and concentrated ammonia water was added to adjust the pH to 8. To form a hydrogel, which is filtered. 12 of this aluminum phosphate
After drying at 0 ° C. for 16 hours, it was baked at 500 ° C. for 2 hours in the air.

2. Production of phosphorus-containing alumina (P doped Al
umina) 1.92 kg of 85% phosphoric acid is mixed with water to make 7.1 L, and this aqueous solution is evenly mixed with 10 kg of alumina at room temperature for 10 minutes, dried at 160 ° C., and dried in air at 500 ° C. for 3 hours. Baked.

Preparation of catalyst samples 20 of each of alumina (for comparison), titania (for comparison), aluminum phosphate, alumina containing phosphorus.
As shown in Table 1 below, 0 g of chloroplatinic acid and an aqueous solution of palladium chloride were carried so that the weight ratio of the noble metal to the permeation support was 0.01 / 1.

[0020]

[Table 1]

Example 2 Performance Evaluation of Acid Catalyst 1. CO conversion rate 2 g of each of the catalysts 1 to 8 produced in Example 1 was placed in a microreactor, and the temperature was raised to 200 ° C. After adjusting the air containing 200 ppm CO to pass at a space velocity of 24,000 m / hr,
The exhaust gas passing through the reactor is collected and the CO conversion is measured. 2. C ₃ H ₈ C ₃ at 300 ° C. in the same manner as the measuring method of the conversion of the CO conversion
The conversion with respect to H ₈ is measured. 3. SO ₂ conversion rate SO ₂ conversion at 400 ° C.
_The conversion rate for ₂ is measured. 4. Soot combustion temperature 2 g of each of the catalysts 1 to 8 produced in Example 1 was taken and mixed uniformly with 0.5 g of soot powder, and then charged into a microreactor. Increase the temperature by 10 ° C per minute for 20
After reaching 0 ° C., the temperature at which the temperature rises rapidly (soot combustion temperature) is measured while increasing the temperature by 1 ° C. per minute.
The measured conversion rates of CO, C ₃ H ₈ and SO ₂ and the soot combustion temperature are shown in Table 2 below.

Example 3 Evaluation of Durability at High Temperature 2 g of each of the catalysts 1 to 8 produced in Example 1 was taken and baked at 600 ° C. for 7 days in the atmosphere. The conversion rates of CO, C ₃ H ₈ and SO ₂ and the soot combustion temperature of these catalysts were measured in the same manner as in Example 2, and the results are shown in Table 2 below.
Expressed in

Example 4 Evaluation of Chemical Stability to Sulfur Oxide 2 g of each of the catalysts 1 to 8 prepared in Example 1 was taken and calcined at 400 ° C. for 7 days in dry air containing 200 ppm of SO ₂ . These catalysts were tested under the same conditions as in Example 2 to measure the conversion rates of CO, C ₃ H ₈ and SO ₂ and the soot burning temperature, and the results are shown in Table 2 below.

[0024]

[Table 2]

As can be seen from Table 2 above, the fusing substrate made of aluminum phosphate or phosphorus-containing alumina has excellent thermal stability at high temperature and chemical stability to sulfur oxides. In fact, it has excellent durability as a catalyst for removing particulate matter of diesel vehicles.

Example 5 Manufacture of Catalyst Body Six EX-54 ceramic single-body filters manufactured by Corning Incorporated in the United States were each provided with 1 L of the impregnated support shown in Table 3 below.
After depositing 100 g each, the catalyst metal was loaded again so that the metal content was 1 wt% based on the deposit support, as shown in Table 3 below. This is dried at 120 ° C. for 12 hours and then fired in air at 500 ° C. for 2 hours to
Six catalyst bodies of No. 6 were produced. In order to evaluate the durability of the catalyst bodies, the catalyst bodies 2 and 4 were left to stand in the air at 600 ° C. for 7 days, and the catalyst bodies 3, 5 and 6 were mixed with SO ₃ 200 ppm.
It was left to stand at 400 ° C. for 7 days in the air containing.

[0027]

[Table 3]

Example 6 Evaluation of Regeneration Performance of Catalyst Body The catalyst bodies prepared in Example 5 were mounted on Petter AV-B supercharged single-cylinder diesel engines manufactured by Carson Company, England, respectively, and the operating speed was 2250.
rpm, cooling water temperature 100 ° C, oil temperature 90 ° C, oil pressure 2.5 bar, air inlet pressure 2230 mbar
Under normal operating conditions, stop the engine bypass valve,
Open the filtration trap valve. Regeneration with a slight opening of the throttle If the current situation does not occur, the throttle was opened further and the exhaust gas temperature was raised to experiment the regeneration of the filter media. When regeneration occurs, the collected particulate matter is burned by catalytic ignition, the back pressure of the engine engine decreases, and the temperature at the rear end of the filter trap rises. The sulfur trioxide content in the exhaust gas is ionic liquid phase chromatography by collecting a predetermined amount of exhaust gas for 2 minutes with a vacuum pump in a mixed solution having a volume ratio of isopropyl alcohol and water of 60:40. Was analyzed by comparison with the standard solution. The regeneration temperature and sulfur trioxide emission of the six catalysts prepared in Example 5 were measured by the above test method and are shown in Table 4 below.

[0029]

[Table 4]

As shown in Table 4 above, the impregnated support made of aluminum phosphate or phosphorus-containing alumina regenerates the filter medium by burning particulate matter at a lower temperature than conventional catalyst bodies. Shows excellent catalytic effect,
Further, it has excellent thermal stability at high temperature and chemical stability against sulfur oxides, and it can be seen that it actually exhibits excellent performance as a catalyst for removing particulate matter of diesel vehicles for a long time.

[0031]

When the catalyst containing the catalyst support produced by the above-mentioned method is mounted on the filter trap to regenerate the filter medium, the thermal stability at high temperature and the sulfur generated during diesel combustion are high. It has excellent chemical stability against oxides, and can maintain the particulate matter removal performance of diesel vehicles for a long time.

Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number for FI Technical location B01J 23/40 ZAB A 8017-4G 32/00 ZAB F01N 3/02 321 A (72) Inventor Gu Bonchul Republic of Korea, Kyungsan Namdo, Ulsan, Chung, Taewadong, Yukon Taewa House Sa-303 (72) Inventor Chang Hyuksan Republic of Korea, Kyungsan Namdo, Ulsan, Namgu, Daldon, Sunkun Apat 6-1308 (72) Inventor Min Kyun-Cul, Republic of Korea, Kyungsan Namdo, Ulsan, Namgu, Yongyun Dong, Yongyun Haus 3-102

Claims (17)

[Claims] 1. A surface of a filter medium is infiltrated with an immersion support made of aluminum phosphate or phosphorus-containing alumina, on which at least one noble metal selected from platinum, rhodium and palladium is infiltrated. A catalyst body for removing particulate matter of a diesel engine, which is characterized in that 2. The filter material is a fire-resistant three-dimensional structure such as ceramic foam, ceramic fiber filter, metal foam, ceramic honeycomb, Wilflow honeycomb monolith, open flow metal honeycomb or metal mesh. The catalyst body for removing particulate matter of a diesel engine according to claim 1. 3. The weight ratio of phosphorus to aluminum (P / A) in the aluminum phosphate as the adhesion support.
The catalyst body for removing particulate matter of a diesel engine according to claim 1, characterized in that 1) is 0.5 / 1 to 1.5 / 1. 4. The phosphorus-containing alumina, which is the adhesion support, has a weight ratio of phosphoric acid to alumina of 0.001 / 1 to 0.
It is 3/1, The catalyst body for particulate matter removal of the diesel engine of Claim 1 characterized by the above-mentioned. 5. The catalyst body for removing particulate matter of a diesel engine according to claim 1, wherein the permeation support is 5 to 200 g per 1 L of the filter medium. 6. The diesel engine according to claim 1, wherein the selected at least one noble metal is 0 to 6 g of platinum, 0 to 6 g of palladium, and 0 to 3 g of rhodium per 1 L of the filter medium. A catalyst body for removing particulate matter. 7. The catalyst body for removing particulate matter of a diesel engine according to claim 1, wherein a weight ratio of the noble metal and the infiltration support is 0.001 / 1 to 0.2 / 1. 8. A) producing aluminum phosphate or phosphorus-containing alumina as an adsorbent support, b) adhering the adsorbent support of step a) to a filter medium, and c) said b. A) a catalyst for removing particulate matter of a diesel engine, which comprises a step of supporting a platinum group solution on the filter medium produced in step a), and a step of d) subjecting the product of the step c) to a high temperature heat treatment. Medium manufacturing method. 9. The method for producing a particulate matter removing catalyst body for a diesel engine according to claim 8, wherein the aluminum phosphate is produced by reacting aluminum nitrate and ammonium phosphate in an aqueous solution. 10. The weight ratio of phosphorus to aluminum (P / Al) when reacting aluminum nitrate and ammonium phosphate in an aqueous solution during the production of the aluminum phosphate is 0.5 / 1 to 1.5 / 1. The method for producing a particulate matter removing catalyst body for a diesel engine according to claim 9, wherein 11. The method for producing a particulate matter removing catalyst body for a diesel engine according to claim 9, wherein the pH during the production of the aluminum phosphate is 7-9. 12. The catalyst for removing particulate matter of a diesel engine according to claim 8, wherein the alumina used in the step of producing the phosphorus-containing alumina has a specific surface area of 1 m ² / g or more. Production method. 13. In the step of producing the phosphorus-containing alumina, 0.001 / 1 to 0.3 / 1 wt based on alumina is used.
9. The method for producing a particulate matter removing catalyst body for a diesel engine according to claim 8, wherein an aqueous solution containing phosphoric acid in an amount of 0.1% is used. 14. The method for producing a particulate matter removing catalyst body for a diesel engine according to claim 8, wherein the permeation support in step b) is 5 to 200 g per 1 L of the filter medium. . 15. The at least one noble metal selected in step c) is 0 to 6 g of platinum per liter of the filter medium,
9. The method for producing a particulate matter removing catalyst body for a diesel engine according to claim 8, wherein the catalyst body is 0 to 6 g of palladium and 0 to 3 g of rhodium. 16. The catalyst body for removing particulate matter of a diesel engine according to claim 8, wherein the weight ratio of the noble metal and the infiltration support is 0.001 / 1 to 0.2 / 1. Manufacturing method. 17. A method for removing particulate matter of a diesel vehicle, which comprises using the catalyst body according to claim 1 or the catalyst body manufactured by the method according to claim 8.