JPS5980330A - Catalyst for removing fine particle in diesel exhaust gas - Google Patents

Abstract

PURPOSE:To obtain the titled catalyst with high efficiency, by a method wherein the surface of a porous carrier having a three-dimensional network structure is coated with activated alumina and Pd is supported by the coated carrier while one element selected from Rh, Ru, Ni, Zn and Ti is further supported thereby. CONSTITUTION:The surface of a porous carrier having a three-dimensional network structure (e.g., cordierite type ceramics) is coated with activated alumina in an amount of 20-200g per 1l of the carrier. Pd is supported by this catalyst carrier in an amount of 0.05-3g per 1l of the catalyst carrier while at least one element selected from Rh, Ru, Ni, Zn and Ti is further supported. By using this catalyst, the removal ratio of a particulate in diesel exhaust gas becomes high and the formation of sulfate is reduced while the rising in pressure loss is low and, therefore, the catalyst extremely high in practical peformance is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION This 9M light relates to a catalyst for removing particulates mainly composed of carbon discharged from diesel engines.

The M components emitted from diesel engines are:
In addition to gaseous Co (carbon oxide), HC (hydrogen carbonate), NOX (w oxide), fine particles whose main component is carbon (hereinafter referred to as ticulate) and S (sulfur) nightide. etc. In 1980, the U.S. Environmental Protection Agency (EPA) determined that the United States had a minimum of 0.297 miles for a JIi car and 0.297 miles for a light Q) rack in the United States.
A plan of 26.9/mile is used for moxibustion 6 and soil. Therefore, it is inevitable that some kind of post-processing device will be needed in the future to meet the rejection value (-6).

Many methods have been proposed so far for removing particulate matter from diesel exhaust. For example, the method described in Japanese Patent Publication No. 56-29581, in which all the exhaust gas is passed through a filter in which alumina is removed from a complex metal wire, is removed! (See Japanese Patent Application Laid-Open No. 12011/1983) A method of passing through a filter so that it passes through the filter,
Alternatively, there are various methods such as a method of removing the exhaust gas by passing it through a combination of a filter and a heater as disclosed in Japanese Patent Application Laid-Open No. 56-72213. A method of removing exhaust gas by passing it through a three-dimensional network structure in which a thermal substance coated with a catalyst (n-type semiconductor oxide) is also disclosed in Japanese Patent Laid-Open No. 55-137040, etc. Proposed. However, and 11. Yes - 4゛ is also self + l + 11 Diesel 4 no 1 air 6 + ' of cars etc. (method of removing particles is 1 However, it has drawbacks such as the possibility that the function of the internal combustion engine may be impaired due to clogging with particulates. Among the above-mentioned methods for removing particulates when installed in a car, the one that uses a substance with catalytic ability in the three-dimensional mesh 41' structure (laminated cloth/ 9f This is the best method.

By the way, as a catalyst for burning and detoxifying particulates of diesel exhaust, it is preferable to use a catalyst that has excellent combustibility of soft hydrocarbons. In other words, the main component in the micro-ome L is carbon, but it is directly produced on carbon, which is then gasified and combusted. Although it is extremely difficult, is it possible to generate fine particles mainly composed of carbon using the combustion of adsorbed hydrocarbons as the ignition source? The catalytic materials for burning hydrocarbons are platinum (Pt), radium (PI), and rhodium (Rh).
Etc. y (Kim M JjM, 'min is net also has Jino l.

However, when the conventional Kikansaku catalyst is used to remove quenched diesel exhaust, aggregation occurs, producing sulfates such as sulfuric acid mist. In other words, diesel engines usually use light oil with a higher S content (tk) than phosphorus, but the S in the light oil is reduced to r in the engine combustion chamber.
It becomes β and becomes SO2 and is discharged. Therefore, diesel cars contain about 10 times more S02 than regular gasoline IIJ. For such a diesel exhaust, F't, )'t-P
When a conventional type 1 catalyst (gold kIt) containing components such as d and Pd is used, S02 in the exhaust gas is oxidized and becomes S03.
It combines with water in the low frA region to form (14f acid mist or sulfuric acid compound (7Jr secondary sulfate)).

The sulfate L-L putty Δcurate d ((1) detected as part of the particulate because it is captured by a constant filter, and when a large amount of sulfate is produced as with conventional noble metal catalysts, V iI'', catalyst included 1] The inconvenience occurs in that the amount of ticulates ii in the outlet gas is more than the particulate components in the gas.

The inventors of the present invention have made efforts to develop a diesel exhaust system that can suppress the conversion of S02 to sulfate and efficiently detoxify and remove particulates. However, in this catalyst of ψ1, activated alumina was added to the coating of a porous carrier having a three-dimensional network structure. 20-200gυU per 11 tanks
0/P radium per 11 catalysts was added to the catalyst carrier.
．． 05 to 3 g, and at least 1) iii l 41!3 selected from rhodium, ruthenium, nickel, 411i lead, and titanium.

The three-dimensional network structure carrier used in the present invention is preferably a cordierite ceramic that is heat resistant and has a low coefficient of thermal expansion, but a heat resistant metal carrier can also be used. Regarding the three-dimensional mesh oak remains of ceramics,
For example, JP-A-56-50165, JP-A-56-625
No. 09 or JP-A-56-41868.

Also, regarding its manufacturing method, please refer to 'kr Kaisho 56-501
No. 65, a slurry consisting of ceramic raw materials, water, and a foam stabilizer is mixed with air and stirred to create a foamy slurry. After pouring this foamy slurry into a mold, it is dried to remove moisture and form a solid product. 1411 shows a method for manufacturing porous ceramic and glass molded products, which is characterized by forming and firing this solid product to make it porous. Furthermore, Japanese Patent Application Laid-Open No. 56-62509 discloses a three-dimensional network structure having internal interconnected spaces with a specific gravity of 03 to 0. fj on the lattice surface of the ceramic porous body skeleton with respect to the field amount of this skeleton
A method for producing porous ceramic structures by nucleating an active layer consisting of activated alumina of 40% by weight and 7 lux for aluminum of 0.5 to 10% by weight has been shown, and also in JP-A-56-1999. No. 41868 describes a method in which an organic polyisocyanate compound, a compound having at least two active hydrogen atoms in the molecule, a ceramic raw material, water, a good cell-opening surfactant, and, if necessary, a blowing agent, are mixed. A method for producing and using reticulated porous ceramics is disclosed, which is characterized by foaming and firing the foam.

On the other hand, an example of afforestation to a heat-resistant metal ゛h three-dimensional mesh (;'' is shown in 11', ♀Kai No. 56-55504,
And the method for making the coins is that they are made with a mausoleum machine that has a space inside that connects three-dimensionally in multiple directions and also connects to the outside. In this step, the liquid of the investment material that does not decompose is filled with M-shaped investment particles to the inside, and the investment material is dried and assimilated. A process of making a complete mold consisting of holes i and +z that have the same shape as the original mold inside the investment material, and metal powder or ceramic powder that has high sinterability after this step 4. A step of pouring a fluid suspension in which a binder and an organic solvent or water are mixed into the holes of the mold made of the investment material and drying and solidifying it, and following this step, metal powder in the fluid suspension. or a step of sintering the iL powder while extinguishing the binder at the sintering temperature of the ceramic powder;
A method for manufacturing a porous body is disclosed in JP-A-56-555 (14-'r'; c.
1itl is shown. In the case of cordierite M'<g corpse, it is preferable that the apparent bulkiness is 0.2 to 0.6 and the pore diameter is 6 to 30 meters/unit. Furthermore, the activated alumina used to coat the surface of the carrier may be of r, δ, η, ρ, θ′4tb, but inactive alumina with extremely small specific surface properties such as α alumina 'Lumina cannot be used because it has a low hydrocarbon adsorption ability and a low rate of collection of paticles and lattice. The appropriate amount of active-rlumina applied to the surface of the carrier is 20 to 2009 per 11 carriers. Examples of salts used to support Pd, which is a catalyst component, include palladium chloride and nitric acid]! There are radium, dinitrodiammine, radium, ie radiumamine compounds, etc., and these salts are made into an acidic or basic water bath solution or dissolved in a solvent, and after adjusting to a predetermined pdg degree, these M solutions are prepared. By impregnating and adsorbing Pd, Ji3 can be retained. ] The amount of palladium supported per carrier is preferably 0.05 to 3 g per φ&=tll of the carrier.・
The mutual i of P radium is 0.05! If it is less than J, the catalytic performance is insufficient, and if it exceeds 3 g, no improvement in the catalytic performance is observed even if more than 3 g is added, and the increase +34 has no effect.

The salts used in this invention to hydrate the catalyst carrier include at least one metal selected from rhodium, ruthenium, dichloride, zinc, and titanium other than radium, including chloride, 111′j acid J, XA Ji・
I can get angry.

The life of a constant gutter as described in 6 above 1'-1-alumina coating 1. Catalyst] 1! A constant V of glossy radium on the body
By using the catalyst of the present invention, which is composed of at least one selected from rhodium, ruthenium, nickel, zinc and titanium, the removal rate of ticulates in diesel exhaust is reduced, and sulfate formation is reduced. , and Jj1 is small in terms of pressure loss, so this catalyst is extremely practical.

Examples of this invention will be described below.

Example cordierite three-dimensional mesh 41・'i 1 area 4-F
i-body (diameter 120mm, length 130+nm,)
I, 3 mesh, apparent bulk specific gravity 0.35) 11 Temporarily cover activated alumina 7SjJ, dry at 110°C,
The regulation was done at ℃.

Next, the activated alumina plate frame catalyst carrier was immersed in a 0°C chloride/P radium water bath solution so that 91.09 Pd per 11 core carriers was supported. Sodium borohydride dissolved in water.

After cleaning it, I washed it with hot water. Finally, this catalyst was dried with xooc and then calcined in 500 ml of steam for 1:1[''] to obtain an older catalyst A.

The catalyst A was immersed in an aqueous titanium trichloride solution that had been subjected to electricity supply so that 4.8 g of Ti was supported per 11 supports of catalyst A, and then drained with water and drained at 100 ml of water. It was dried at .degree. C. and further calcined in air at 500.degree. C. for 1 hour to obtain a formed catalyst B.

Regarding this catalyst B, the catalyst (f4:i
ii: g・1′ value test (・P tiki rate removal rate,
庺RUFUUTE generation) i and touch are L's utility power 1εj loss upper row (Hate's test bite), and as a result, all Figures 2 ~ r
Shown in Figure A”+4.

Example Example hiii For every 11 supports of catalyst A obtained according to rule 1, 5
9! ! The catalyst A was immersed in an aqueous solution of 1419 nickel containing concentrated JW to support N1. It was drained, dried at 100℃, and further dried at 50℃.
The finished catalyst C was heated in QC air for 1 hour. A catalyst performance evaluation test was conducted on this catalyst C in the same manner as in Example 1, and the results are shown in FIGS. 2 to 4.

Example 3 With hfu example 1? 6 per 11 supports of W catalyst A
．． After immersing the catalyst A in a 1111 lead nitric acid aqueous solution whose concentration was adjusted so that 5 g of Zn was supported, it was placed in a water bath 7f.
The catalyst was taken out from t, dried at 100°C, and further calcined in air at 500°C for 1 hour to obtain a finished catalyst. A catalyst performance evaluation test was conducted on this catalyst in the same manner as in Example 1, and the results are shown in FIGS. 2 to 4.

Example 4 For each of the 11 and 9 plants of fq insect A that were grown in Example 1,
05g of 11 cities lasted 4 times. N of IW like a sword
The catalyst A was immersed in the adjusted rhodium chloride water bath solution, then removed from the water bath solution, dried at 100°C, and further calcined in air at 400°C for 1 hour to obtain the completed catalyst E. Ta. A catalyst performance evaluation test was conducted on this catalyst E in the same manner as in Example 1, and the results are shown in FIGS. 2 to 4.

Example 5 Per 11 4-t4 bodies of catalyst A obtained in Example 1, 0
．． The catalyst A was poured into a ruthenium chloride solution prepared in a ruthenium chloride solution so that 5I of Ru was retained for 4 hours, and then removed from the water bath, dried at 100C, 50
Completed catalyst F was obtained by six-phase reaction in air at 0° C. for 1 hour. This catalyst F was subjected to a catalyst performance evaluation test in the same manner as in Example 1, and the results were rated F: 2nd to 4th.

1711 (Siri 1) Catalyst A sealed by the method shown in Practical HIFI Example 1 was subjected to catalyst performance evaluation test 14 in the same manner as Ichinof Example 1.
...i was carried out, and the results are shown in Figs.

Comparative Example 2 4! of Catalyst A obtained in Example 1! ! 14 per body 11
The catalyst A was immersed in a cerous nitrate water bath solution whose magnetism was adjusted so that 0 g of cerium (Ce) was supported, then taken out from the water bath solution and dried at 100'C! The catalyst was further calcined in air at 500C for 1 hour to obtain a finished catalyst G. A catalyst performance evaluation test was conducted on this catalyst G in the same manner as in Example 1, and the results are shown in FIGS. 2 to 4.

Comparison row 3 The concentration was adjusted so that 2.0.9 of 5 (Ag) was mixed per 1 of the IJLA support in 1 ft of silver nitrate water, W. The catalyst A
was immersed, and further reduced with an aqueous sodium borohydride solution and washed with hot water. Next, this catalyst was dried at 100°C and further calcined in air at 500°C for 1 hour to obtain a completed catalyst H'f. A catalyst performance evaluation test was conducted on this catalyst H in the same manner as in Example 1, and the results are shown in Figure 2~
Figure 4 shows the diagram.

Comparative Example 4 Cordierite three-dimensional mesh 4A corpse (diameter 120 sieve,
Length 130 Inl + 1 particle size 13 mesh, 0 tines
．． 35) Plate 75g of activated alumina per liter,
It was dried at ℃ and calcined at 700U. Then 0.2 per 11 of said carriers. ! The upper W was added to a dinitrodiaminoplatinum water bath solution with a concentration of Wa'N so that platinum (pt) of 9 was supported.
After soaking the activated alumina catalyst carrier, it was taken out from the solution, dried at 100°C, and further calcined in air at 400°C for 3 hours to obtain the completed catalyst I'f:A4. Regarding this test, a catalyst performance test was conducted in the same manner as in Example 1, and the results are shown in FIGS. 2 to 4.

Comparative Example 5 Cordierite three-dimensional mesh 114 structure (diameter 120 m
m, length 130 questions, particle size 13 mesocy, apparent specific gravity tJ,
35) Activated alumina 75 per liter! j- was tested, dried at 110'C, and calcined at 700C. Then s
So that 0.1 g of pt was supported per 11 N4μ bodies (
(:% IJI) After immersing the tested catalyst carrier of the above activated alumino in a prepared dinitrodiaminoplatinum water cci solution, it was taken out from the side, dried at 100°C, kept under air, and further heated to 400°C under air. It was baked for 3 hours inside.

Next, the catalyst was immersed in an IJI-conditioned aqueous palladium chloride solution at +6k K so that ()5g of Pd was supported per 11 of the 411 bodies of this catalyst, and further reduced with an aqueous sodium borohydride solution. After that, I washed it with hot water. Then, after drying this catalyst at 100°C,
A completed catalyst J was obtained by firing in nitrogen atmosphere at 0C for 1 hour. A catalyst performance evaluation test was conducted on this catalyst J in the same manner as in Example 1, and the results are shown in Figures 2 to 4.

In addition, in Comparative Examples 4 and 5, the pt catalyst, Pt
The amount of Pt was set to 115% of Pd in order to keep the price of precious metals at the same level for each catalyst supported.

Performance evaluation tests were conducted on catalysts A-J obtained in Examples 1 to 5 and Comparative Examples 1 to 5 above. A schematic diagram of the performance d/r value testing device 6 is shown in FIG. The engine IK used was a 2,200cc L-type engine manufactured by Toyota Motor Corporation. Engine operating condition is 2.00 Or
pm, j-! The test was conducted with a load of 8 kg-tn.

Two collection containers fully filled with the catalyst are installed in the middle of the exhaust system of this engine J, and sampling pipes are installed before and after the collection container 2, and a three-way cock 4, a filter case 6, and a suction bong are installed in the middle of each. , I was able to take gas meter 8. Sampling pipe 0 to filter case
A heating heater 3 was wrapped around the.

If the temperature of the sampling gas is low, moisture will condense and some particles will stick to the sampling pipe, making it impossible to accurately determine the particulate matter 9. The heating heater 3 was wrapped to prevent moisture condensation. The suction pump was installed in order to allow the exhaust gas to flow at a foot flow velocity, and the groove gas meter 8 was installed in order to measure the flow rate fAX of the exhaust gas. The filter case 6 contained a Teflon-coated filter with a diameter of 47 mm. As will be described later, the manometer 5t was installed as shown in the figure in order to control the catalyst pressure (H loss rise to 1115f).

I tried to measure it by switching on and off the exhaust gas by switching the three-way cock 4, but...
The measurement method was carried out by passing the exhaust gas of 401 through a Teflon-coated filter in the filter case 6 and measuring the amount of particulates in the exhaust gas collected before and after the catalyst.

The particulate removal rate was calculated using the following formula, and the results are shown in Figure 11g2.

Particulate Removal Rate Value 1 Next, sulfate concentration in the exhaust gas when catalyst A-Jf was used was measured. The measurement was carried out using 11 sampled filters in the same manner as the ticulate measurement, and quantitative analysis was carried out by barium trifluorophotometric titration. The results are shown in Figure 3.

Regarding pill 'M, which is an increase in pressure loss, in Fig. 1, a mercury manometer is installed in the catalyst container bending extension I, and the engine is set to 2.0
The L1- in front of the catalyst container when the operation was started at 0 Orpm and the 6ij office after 24 hours of engine relocation were measured, and the pressure was calculated assuming that the pressure at 7 corresponds to the increase in pressure loss of the catalyst. stomach! The results obtained are shown in Figure 4.

As is clear from the results shown in FIGS. 2 to 4 above, catalysts B, C, and D shown in Examples of the present invention.

E and F are not shown in the comparative example and are catalysts A, G, I (
.

Compared to (2) and J, it is an extremely practical catalyst as it is comprehensively superior in three respects: a higher removal rate of 7F teikyulate, less sulfate formation, and a smaller increase in pressure loss.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of a performance planning device for a catalyst for removing particulates from diesel exhaust, and Fig. 2 is a bamboo cultivation tank Mod-b catalyst (13, C, I) of the present invention. G: and F) Comparative catalysts (A, G, H
. ■ and J) to clean the exhaust gas.
If removed, the removal rate of ・7j<
Figure 3 is a bar diagram showing the amount of IJ sulfate produced using catalysts A to J, and 21
! Figure 4 shows the state (using income or J, 2. (J (10r
pm-C 24-hour engine operation start')
73 It is a bar diagram showing the repulsive force loss of the catalyst.
1 Heater, 4... Three-way cock, 5... Manometer, 6... Filter case, 2... Suction 7J
Hinno 5.8...Gas meter. Applicant's representative Patent attorney Takeshi Suzue Chapter 1 Figure 2 AS CDEFGHIJ Type of intermediary

Claims (1)

[Claims] Table 1hi of a porous carrier having a first-day structure
3g, rhodium, ruthenium, 2,
A catalyst for removing particulates from diesel exhaust, which supports at least one of the following compounds: chlorine, zinc, and titanium.