JPS614532A - Manufacture of integral structure type catalyst for purifying waste gas - Google Patents

Abstract

PURPOSE:To increase the gas purifying degree and durability of the titled catalyst by mixing activated alumina having specified narrow pore diameter with alumina sol, crushing the mixture to make slurry and forming an aluminum oxide coating on the surface of a catalyst. CONSTITUTION:Activated alumina contg. cerium preliminarily wherein >=80% all narrow pore volume is occupied by the narrow pore volume of 200-600Angstrom narrow pore diameter is mixed with cerium oxide and alumina sol and the mixture is crushed and the obtained slurry is impregnated into an integral structure type carrier, dried and calcined and thereafter the essential catalytic metals are deposited on the composite oxide coating formed on the carrier. Separately, after the slurry of mixed and crushed material of both alumina wherein >=80% all narrow pore volume is occupied by the narrow pore volume of 200-600Angstrom narrow pore diameter and alumina sol is coated on the carrier deposited with the above-mentioned essential catalytic metals, it is dried, calcined to manufacture the waste gas purifying catalyst for removing carbon monoxide, hydrocarbons and nitrogen oxides contained in the waste gas.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for manufacturing an exhaust gas purifying catalyst of an integrated structure used for purifying exhaust gas, particularly exhaust gas from automobiles and the like.

(Prior Art) As a conventional method for producing an exhaust gas purifying catalyst of a monolithic structure, there is a method in which, for example, an activated alumina layer is provided on the surface of a monolithic carrier, and then a catalytic metal is supported thereon to form a catalyst. For example, in the method described in JP-A-52-27088, activated alumina 4 containing 10% ceria (ceo2) is
Immerse the carrier in 0-45% by weight slurry and heat at 125°C.
After drying, it is fired at 500°C in an air atmosphere. Next, this carrier was immersed in a nickel nitrate solution and heated to 125°C.
After drying at
After drying at °C, it is calcined in an air atmosphere at 500 °C to become a catalyst. Note that other base metal salts are also used in the nickel nitrate impregnation step.

Another method is to mix cerium nitrate, activated alumina, and nitric acid to form a slurry without using ceria, coat it on a monolithic carrier, and dry it at 125°C.
There is also a method of firing in an air atmosphere at 500'C, and at the time of this firing, the cerium nitrate is
becomes.

(Problems to be Solved by the Invention) In the conventional manufacturing method of the monolithic exhaust gas purification catalyst as described above, the catalyst metal was present near the surface of the activated alumina layer, so lead When a fuel containing (pb) is used for long-distance driving, there is a problem in that the active points of the catalyst are coated with accumulation of lead and the like, resulting in a loss of catalyst activity.

In order to solve this problem, a method is disclosed in JP-A-50-95188 in which a catalyst and alumina are supported on an inert carrier and then covered with alumina. JP-A-53-85792 discloses a method in which an aqueous solution of an aluminum component, preferably aluminum sulfate, which is a catalytically active alumina precursor is deposited, dried, and calcined. However, these methods do not consider the alumina that coats the catalyst metal, and usually use commercially available activated alumina (according to our measurements, commercially available alumina has a pore diameter of 600 Å or more), and do not use fuel containing lead. When used, the problem remains that the catalyst deteriorates significantly after durability.

(Means for Solving the Problems) This invention was made by focusing on the conventional problems as described above, and includes mixing and pulverizing activated alumina and alumina sol having a specific pore size on the surface of the catalyst. The above problem is solved by forming an aluminum oxide film as a slurry.

That is, in the method for manufacturing an integrally structured exhaust gas purifying catalyst of the present invention, cerium-containing 'gt)Th'
@”o′!daii”v@%7′v<-3-H-b+)
fy.

Alumina oxide and alumina sol are mixed and crushed to form a slurry.
□;-, impregnate this slurry into a monolithic carrier,
Dry and bake. As a result, an oxide film made of a composite oxide or mixed oxide is formed on the carrier. Next, the main catalyst metal, such as one or more noble metal components such as platinum, rhodium, and palladium, is supported on this oxide film, and activated alumina and alumina sol having a specific pore size are mixed and ground to form a slurry. Then, the main catalyst metal is coated on the carrier, dried and fired to form an aluminum oxide film. The catalyst formed in this way does not deteriorate its purification performance even if the amount of the main catalyst metal such as precious metals such as platinum, rhodium, and palladium is reduced, and even when fuel containing lead is used for automobiles. The durability is also sufficient.

When preparing a slurry by mixing and pulverizing activated alumina with a specific pore size that contains cerium in advance, cerium oxide, and alumina sol, the amount of cerium contained in the activated alumina is 1 to 1 to alumina in terms of metal. Preferably, the amount of cerium oxide is 5 to 40% by weight.
is preferred.

Even if the amount of cerium contained in activated alumina exceeds 5% by weight (metal equivalent) and the amount of cerium oxide powder added exceeds 40% by weight, there is almost no effect of increasing the amount of cerium; If the amount of cerium oxide contained is less than 1% by weight (metal conversion 'a, ), and if the blended cerium oxide powder is 5% by weight, the effect of their addition is insufficient compared to the performance required by the inventors. It is.

Furthermore, the pore diameter of the activated alumina used in this invention is 200.
If the number of pores is less than 600 people or more than 600 people, it is undesirable that catalyst deterioration after durability is large when fuel containing lead is used, and the pore volume of pores from 200 to 6008 people is The higher the proportion in the pore volume, the better, but increasing the V' ratio leads to increased costs;
Since it is technically difficult, the ratio is preferably 80% or more. Therefore, in this invention, the pore diameter is 200
Use activated alumina in which the pore volume accounts for 80% or more of the total pore volume.

(Example) The present invention will be explained below with reference to Examples, Comparative Examples, and Test Examples.

Example 1 40-60t of water was put into a 1,001 liter reactor and heated to 100°
It was heated to C. There as alumina (A1208) 5
゜Aluminum nitrate aqueous solution containing 4% by weight (ht (No.
8) 8) was added until the pH reached 2. After holding for 5 minutes, alumina (Al2O8) was added for 20 minutes.
A sodium aluminate aqueous solution containing 1% by weight (NaAl1.
) was added until the pH reached 10. After keeping it as it was for 5 minutes, an aqueous aluminum nitrate solution was added to adjust the pH to 2. Thereafter, the same operation was repeated so that the number of pH fluctuations was 13 times, and after the test, an aqueous sodium aluminate solution was added to obtain PHIO. The generated pseudo-boehmite precipitate was washed with water to remove Na2O until Na2O was 0.02% by weight or less based on Al2O. The precipitate was filtered to give a cake containing 20 to 30% by weight of A7208.

Alumina gel was made into granules with a diameter of 2 to 4 mm using a granulator.

Dry at 120°C, bake at 500°C for 8 hours,
1 alumina. The central pore diameter of activated alumina is 385
The pore volume with a pore diameter of 200 Å to 600 Å occupied more than 80% of the total pore volume. This punishment 11
A granular carrier (particle size 2 to 4 mm) whose main component is gamma alumina and whose pore size is 200 to 600 mm and whose pore volume accounts for 80% or more of the total pore volume is impregnated with a cerium nitrate aqueous solution and then dried. It was fired in air at 600° C. for 1 hour to obtain a carrier containing 3% by weight of cerium oxide based on alumina in terms of metal.

25639, activated alumina granular support 9 containing the above ceria
469 and ceria powder 491 were mixed in a ball mill, and s
Milled for 6 hours at o rpm. A monolithic carrier base material (1, 7, 1
! The process of immersing 400 cells/1n2), air blowing and drying was repeated three times to deposit the oxide coating layer.
2 in an air atmosphere at 0°C? Time baking was performed. At this time, the total amount of alumina and cerium oxide deposited was 340 l/kg.

Furthermore, this carrier with alumina and cerium oxide attached was immersed in a mixed aqueous solution of chloroplatinic acid and rhodium chloride, and the amount of platinum and rhodium attached was 0.779 for platinum and 0.1 for rhodium.
After supporting the film to a particle size of 89%, it was fired at 600° C. for 2 hours in an air atmosphere.

Furthermore, a granular carrier (particle size 2 to 4) whose pore size is from 20 OA to 600 A and whose pore volume accounts for 80% or more of the total pore volume (particle size 2 to 4) is mixed with 10002 and alumina sol (boehmite alumina 10% by weight). % suspension to 1
A sol obtained by adding 0% by weight of HNO8 was mixed in a ball mill and pulverized at SO rpm for 6 hours, then the catalyst was immersed in the liquid containing alumina, air blown, and dried at 650°C. Catalyst 1 was obtained by calcination in an air atmosphere for 2 hours. At this time, the amount of alumina deposited on the outermost surface layer was 1009/+.

Example 2 A catalyst was prepared in the same manner as in Example 1 except that cerium-containing activated alumina granular carrier 1.878 f7, alumina sol 24789, and ceria powder 1447 were used to obtain catalyst 2.

Example 3 In Example 1, activated alumina granular carrier containing cerium 1103, alumina sol 256.89, ceria powder 3
34; Catalyst 3 was prepared using the same method except that
I got it.

Example 4 In Example 1, 847 g of active alumina granular carrier containing cerium, 2563 g of alumina sol, and 590 g of ceria powder were added.
A catalyst was prepared in the same manner except that catalyst 4 was obtained.

Example 5 In Example 1, the amount of deposited platinum and rhodium was changed to
A catalyst was prepared in the same manner except that platinum was supported in an amount of 1.917 mm and rhodium was supported in an amount of 0.19 mm to obtain a catalyst 5.

Example 6 A catalyst Ff41j was prepared in the same manner as in Example 2, except that the amount of platinum and rhodium deposited was 1.91 g of platinum and 0.199 g of rhodium, respectively.
I got it.

Example 7 A catalyst was prepared in the same manner as in Example 3 except that platinum and rhodium were supported in an amount of 1.91° for platinum and 0.199° for rhodium, respectively, to obtain catalyst 7.

Example 8 A catalyst was prepared in the same manner as in Example 4, except that platinum and rhodium were supported in an amount of 1°91 for platinum and 0°199 for rhodium, to obtain catalyst 8.

Example 9 Catalyst 9 was obtained in the same manner as in Example 1, except that alumina sol 26489, activated alumina granular carrier containing cerium (12511' in terms of cerium metal equivalent) 12511', and ceria powder 94 ml were used.

Example 10 Catalyst 1o was obtained in the same manner as in Example 1, except that alumina sol 2478, activated alumina granular carrier containing cerium (1% by weight as cerium metal) 6979, and ceria powder 825 were used.

Example 11 Catalyst 11 was obtained in the same manner as in Example 1, except that 2568!7 g of alumina sol, 946 g of active alumina granular carrier containing cerium (5% by weight in terms of cerium metal), and 553 g of ceria powder were used.

Example 12 Catalyst 12 was obtained in the same manner as in Example 1, except that alumina sol 25639, active alumina granular carrier containing cerium (5% by weight in terms of cerium metal) 6519, and ceria powder 786 were used.

Example 13 In Example 1, the noble metal aqueous solution to be immersed was mixed with a mixed water bath solution of palladium chloride and rhodium chloride, and the amount of palladium and rhodium deposited was 0.77 palladium, respectively.
Catalyst 13 was obtained in the same manner except that rhodium was supported in an amount of 0.18 g.

Example 14
- In Example 2, a mixed bath solution of palladium chloride and rhodium chloride was used for the precious metal aqueous solution to be immersed, and the amount of deposited palladium and rhodium was adjusted to 0°77% of palladium, respectively.
9. Catalyst 14 was obtained in the same manner except that rhodium was supported at 0°189.

Example 15 Practical IJfi Example 8G Here, the metal water bath solution to be immersed is a mixed aqueous solution of palladium chloride and rhodium chloride,
The adhesion amount of palladium and rhodium was reduced to palladium 0.
．． Catalyst 15 was obtained in the same manner except that rhodium was dried for 1 hour so that the rhodium OJ89 was obtained.

Example 16 In Example 4I, the metal closed aqueous solution to be immersed was mixed with a mixed aqueous solution of palladium chloride and rhodium chloride, and the adhesion amount of palladium and rhodium was reduced to 0.77 palladium, respectively.
9, catalyst 16 was obtained in the same manner except that rhodium was supported at 0.189.

Example 17 In Example 1, the noble metal aqueous solution to be immersed was a mixed aqueous solution of palladium chloride and rhodium chloride.
, Catalyst 17 was obtained in the same manner except that rhodium was supported at 0.199%.

Example 18 In Example 2, using a mixed aqueous solution of palladium chloride and rhodium chloride to immerse the Takaai River bathing liquid, palladium and rhodium 4 FJk were each immersed in palladium 1.
, 919 and rhodium 0.199 G. Catalyst 18 was obtained in the same manner except that rhodium was supported in the same manner.

Example 19 In Example 3, a mixed aqueous solution of palladium chloride and rhodium chloride was used to support the Koma metal water bath solution to be immersed so that the amounts of palladium and rhodium deposited were 1.91 palladium and 0.199 rhodium, respectively. Catalyst 19 was obtained in the same manner except that.

Example 20 In Example 4, the aqueous solution of funds 44 to be immersed was
Catalyst 2 () was obtained in the same manner except that a mixed aqueous solution of palladium chloride and rhodium chloride was used to support palladium and rhodium in amounts of 1.91 g of palladium and 0.197 g of rhodium, respectively.

Example 21 In Example 1, using a mixed aqueous solution of chloroplatinic acid, palladium chloride, and rhodium chloride for the precious metal aqueous solution to be immersed, platinum, palladium, and rhodium ferrites were respectively immersed.
Catalyst 21 was obtained in the same manner except that platinum was supported in an amount of 0.885 g, palladium was 0.3'859 N, and rhodium was 0.139 g.

Example 22 In Example 2, using a mixed aqueous solution of chloroplatinic acid, palladium chloride, and rhodium chloride as the noble metal aqueous solution to be immersed, the N m of platinum, palladium, and rhodium was 0.3859 for platinum and 0.385 for palladium, respectively. Catalyst 22 was obtained in the same manner except that 0.137G of rhodium was supported.

Example 23 In Example 8, the noble metal aqueous solution to be immersed was mixed with platinum, palladium, and rhodium using a mixed rootstock bath solution of chloroplatinic acid, palladium chloride, and rhodium chloride.
L'1 is platinum 0.3859 and palladium 0, respectively.
Catalyst 23 was obtained in the same manner except that it was supported so that the amount of asts was 9 and rhodium was 0.187.

Example 24 The noble metal aqueous solution to be immersed in Example 4 was immersed in a mixed aqueous solution of chloroplatinic acid, palladium chloride, and rhodium chloride, and the adhesion amount of platinum, palladium, and rhodium was adjusted to 0.885% of platinum, respectively. A catalyst 24. I got it.

Example 25 In Example 1, using a mixed aqueous solution of chloroplatinic acid, palladium chloride, and rhodium chloride as the noble metal water bath solution to be immersed, the amounts of platinum, palladium, and rhodium were adjusted to 559% of platinum O0 and 0% of palladium, respectively. , 9559 and rhodium 0.1991.Catalyst 25 was obtained in the same manner except that rhodium 0.1991.

Example 26 In Example 2, the aqueous solution to be immersed was
Using a mixed 1-aqueous solution of chloroplatinic acid, palladium chloride, and rhodium chloride, the adhesion amounts of platinum, palladium, and rhodium were determined to be 0.9557 for platinum and 0.955 for palladium, respectively.
9, catalyst 26 was obtained in the same manner except that rhodium was supported at 0.199%.

Example 27 In Example 3, a mixed aqueous solution of chloroplatinic acid, palladium chloride, and rhodium chloride was used as the noble metal aqueous solution to be immersed, and the adhesion amounts of platinum, palladium, and rhodium were adjusted to 0.955 g of platinum and 0.955 g of palladium, respectively. Catalyst 27 was obtained in the same manner except that rhodium was supported at 0.199%.

Example 28 In Example 4, the noble metal aqueous solution to be immersed was mixed with a mixed aqueous solution of chloroplatinic acid, palladium chloride, and rhodium chloride. Catalyst 28 was obtained in the same manner except that it was supported at a concentration of 0.199.

Comparative Example 1 A granular carrier mainly composed of gamma alumina (particle size between 2 and 4) was impregnated with an aqueous cerium nitrate solution and dried at 600°C.
The product was fired in air for an hour to obtain a carrier containing 8% by weight of cerium oxide based on alumina in terms of metal.

Next, 2563 g of alumina sol (a sol obtained by adding 10 wt M% HNO3 to a 10 wt M% boehmite alumina suspension), 9469 g of the activated alumina granular carrier containing the above ceria, and 491 g of ceria powder were mixed in a ball mill, Milled at Bo rpm for 6 hours. This alumina-containing liquid (coating liquid) is added to the monolithic carrier base material (1
The process of immersing a cell (71,400 cells/1n2), air blowing, and drying was repeated three times to deposit an oxide coating layer, followed by baking in an air atmosphere at 650°C for 2 hours.

The total amount of alumina and cerium oxide deposited at this time was 8
It was 409/15T-.

Furthermore, this carrier with alumina and cerium oxide attached was immersed in a mixed aqueous solution of chloroplatinic acid and rhodium chloride, and the amount of platinum and rhodium attached was 0.772 for platinum and 0.1 for rhodium.
After supporting the catalyst in an amount of 8 g, it was calcined in an air atmosphere at 600° C. for 2 hours to obtain catalyst A. Note that most of the cerium-containing aluminas had pore diameters of 600 pores or more.

Comparative Example 2 In Comparative Example 1, activated alumina granular carrier containing cerium 13789, alumina sol 24789, ceria powder 1
Catalyst B was prepared in the same manner except that 44q was used.
I got it.

Comparative Example 3 In Comparative Example 1, activated alumina granular carrier containing cerium 1103, alumina sol 2568, and Shichiria powder 3
The catalyst was prepared using the same method except that the i! A catalyst C was obtained.

Ratio example 4/Comparative example 1, activated alumina granular carrier containing cerium 847, alumina sol 25689, and hexadia powder 59
A catalyst was prepared in the same manner except that 0 was used.

Comparative Example 5 1 A'Mi'zo'' (a sol obtained by adding 10% by weight of HNO3 to a 1° heavy weight% liquid) 26489, activated alumina granules/carrier 13529 Mix in a ball mill, s o
Milled for 6 hours at rpm. A monolithic carrier base material (1°7 l 40
0 cell/1n2) was immersed, air-blown and then dried three times, and the alumina coat layer was heated by +1.
Firing was performed in an air atmosphere at 50°C for 2 hours.

At this time, the alumina adhesion ■ was 840! It was set to 7/ke.

Furthermore, this carrier with alumina attached was immersed in a mixed aqueous solution of chloroplatinic acid and rhodium chloride, and the amount of platinum and rhodium deposited was 0.77 g for platinum and 0.18 g for rhodium, and then heated in air at 600°C. Firing was performed in an atmosphere for 2 hours.

In addition, 1000 gamma alumina-based granular carrier (particle size between 2 and 4) with a pore size of 200 to 600 pores and a pore volume accounting for 80% or more of the total pore volume and 3000 ml of alumina sol were added. Mix in ball mill, 80 rp.
After pulverizing for 6 hours at 650 m
Catalyst E was obtained by calcination for 2 hours in an air atmosphere at °C.

At this time, the amount of alumina deposited on the outermost surface layer was 1002/piece.

Ratio example 6 In ratio example 5, alumina sol 25689, active t-t
In addition to 946 pieces of alumina grain carrier, 491g of ceria powder
A catalyst was prepared in the same manner except that catalyst F
I got it.

Comparative Example 7 A catalyst was prepared in the same manner as in Example 1, except that cerium-containing activated alumina granular carrier 13529 and alumina sol 2648 were used, and ceria powder was not used.
I got it.

Example 29 A catalyst was prepared in the same manner as in Example 1 except that cerium-containing activated alumina granular carrier 59/) 9, alumina sol 2477i7, and Shichiria powder 9299 were used to obtain catalyst 29.

Example 80 A catalyst was prepared in the same manner as in Example 1 except that 94 g of activated alumina granular carrier containing cerium, 2563 Gl of alumina sol, and 491 g of ceria powder were used to obtain catalyst 80.

Example 81 In Example 1, 594 g of active alumina granular carrier containing cerium, alumina sol 24779, ceria powder 92
Catalyst 81 was prepared in the same manner except that 9 g was used.
I got it.

Comparative Example 8 A catalyst was produced in the same manner as in Example 1, except that a granular support containing gamma alumina as a main component and having a pore diameter of 100λ to 200゛λ and a pore volume accounting for 80% or more of the total pore volume was used. was prepared to obtain catalyst H.

Comparative Example 9 A catalyst was produced in the same manner as in Example 1, except that a granular support mainly composed of gamma alumina with a pore diameter of 600 to 1000 pores and a pore volume of 80% or more of the total pore volume was used. was prepared and a catalyst was obtained.

Test Examples Catalysts 1 to 81 obtained in Examples 1 to 81 and Comparative Examples 1 to 9
The obtained catalyst was subjected to actual vehicle durability (engine durability) under the following conditions, and the purification rate of 10 mode emission was measured, and the purification rate was Vηco×ηN.

as shown in Table 1.

Engine durability conditions Catalyst Integrated noble metal catalyst Catalyst outlet temperature Approximately 750°C Space velocity Approximately 70,01r-1 Durability time 100 hours Engine Displacement 2200 CC gasoline
Amount of lead 6~/U.S. gallon Next, for the alumina used in Example 1, Comparative Example 8, and Comparative Example 9, the amount of lead was 2 at 650'C, respectively.
Time heat treatment J 1 piece, *1□. Yu, wa□,
The diameter, volume, and volume were measured and the obtained results are shown in Figure 1. In Figure 1, curve 1 indicates the alumina of Example 1,
Curve 2 shows the results for alumina of Comparative Example 8, and curve 3 shows the results for alumina of Comparative Example 9.

(Effects of the Invention) As explained above, according to the present invention, activated alumina supporting cerium and having a specific pore size, cerium oxide, and alumina sol are mixed and ground to form a slurry, and a slurry is formed into an integrated carrier. Coated with a slurry, dried and fired, combined with the main catalyst metal component, dried and fired, mixed and ground activated alumina with a specific pore size and alumina sol, and coated with a slurry to form an alumina film. Because of this structure, the resulting catalyst has a significantly improved exhaust gas purification rate and improved durability, which has the effect of being able to show a high purification rate even with a low amount of main catalyst metal.

[Brief explanation of drawings]

FIG. 1 is a curve diagram showing the relationship between the pore diameter and pore volume of alumina used in Example 1, Comparative Example 8, and Comparative Example 9.

Claims (1)

[Claims] 1. Pre-contained cerium with a pore diameter of 200
Activated alumina with a pore size of Å to 600 Å and a pore volume of 80% or more of the total pore volume, cerium oxide, and alumina sol are mixed and pulverized to form a slurry, and this slurry is impregnated into an integral structure carrier, dried, and fired, A main catalyst metal is supported on a film of a composite oxide or mixed oxide formed on a carrier, and activated alumina and alumina sol have a pore diameter of 200 Å to 600 Å and a pore volume of 80% or more of the total pore volume. to remove carbon monoxide, hydrocarbons and nitrogen oxides from exhaust gas. A method for manufacturing an integrated structure exhaust gas purification catalyst.