JP2771364B2 - Catalytic converter for automotive exhaust gas purification - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION This invention is an automatic formed by arranging C D cam heater, a main monolith catalyst and zeolite adsorbent
The present invention relates to a catalytic converter for purifying vehicle exhaust gas .

[0002]

2. Description of the Related Art Catalytic converters used for purifying exhaust gas from automobiles and the like need to be heated to a predetermined temperature or higher in order for the catalyst to exert a catalytic action. However, if the temperature of the catalyst has not been sufficiently raised, it is necessary to heat the catalyst. Conventionally, as a proposal for heating such a catalyst, for example, a technique described in Japanese Utility Model Laid-Open No. 63-67609 is known. Japanese Utility Model Application Laid-Open No. 63-67609 discloses a catalytic converter in which an electrically conductive metal monolith catalyst in which a metal carrier is coated with alumina is disposed close to the upstream side of a ceramic main monolith catalyst.

[0003] In addition, harmful components (HC, C
O, NO _x ), especially HC (hydrocarbon) causes photochemical smog (oxidant), so regulations are being tightened, and HC emitted in large quantities at engine start-up
Attempts have been made to purify water using the adsorption action of zeolite. For example, an automobile exhaust gas purifying apparatus in which a purifying catalyst and an adsorbent such as zeolite or an adsorbent carrying a catalyst are arranged in an exhaust gas system has been proposed.
(For example, JP-A-2-75327, JP-A-2-1-1
(See JP-A-73312 and JP-A-2-135126.) JP-A-2-126937 discloses an adsorbent in which a metal carrier is coated with zeolite.

[0004]

However, the catalytic converter disclosed in Japanese Utility Model Laid-Open Publication No. 63-67609 is composed of a metal monolith catalyst as a pre-heater and a main monolith catalyst.
There is a problem that the C component is difficult to be purified. In addition, a vehicle exhaust gas purifying apparatus in which a purifying catalyst and an adsorbent such as zeolite are arranged upstream of the purifying catalyst in the exhaust gas system (JP-A-2-7532)
No. 7) discloses that H is produced by an adsorbent on the upstream side of the purification catalyst.
Even if C is adsorbed, there is a problem that HC is desorbed from the adsorbent together with warm-up, and as a result, a considerable amount of HC passes through the purification catalyst.

Japanese Patent Application Laid-Open No. 173332/1990 discloses that a catalyst is provided in a main passage and an adsorbent is provided in a bypass passage. Exhaust gas is passed through the bypass passage by a switching means when the engine is started. A technique is disclosed in which the exhaust gas is caused to flow to the catalyst in the main passage by the switching means when the temperature reaches the temperature.However, in this case, waiting until the catalyst in the main passage is completely warmed up requires a complicated mechanism, and the catalyst in the main passage itself becomes complex. The passage of the unpurified components through the catalyst until the water is warm cannot be ignored.

Further, in an automobile exhaust gas purifying apparatus in which an exhaust gas system is provided with a purifying catalyst and an adsorbent carrying the catalyst upstream thereof (Japanese Patent Application Laid-Open No. 2-135126), the purifying catalyst uses the heat capacity of the adsorbent itself. There is a problem that the rise of the catalyst is delayed, and furthermore, even if a catalyst component is added to the adsorbent, its capacity is limited, and there is a drawback that sufficient purification cannot be performed. Further, Japanese Patent Laid-Open No. 2-126937 describes only adsorbent, CO, HC, it is not described catalytic converter in the exhaust gas including NO _X. Further, in any of the above-mentioned known examples, the zeolite used for the adsorbent is Y-type or mordenite-type, and has a problem in heat resistance and simultaneously strongly adsorbs moisture in exhaust gas,
Decreases the adsorption capacity of the adsorbent.

[0007]

Therefore SUMMARY OF THE INVENTION The present invention has an object to provide a medium converter catalyst for purifying an automotive exhaust gas was to solve the above conventional problems. And its object is, according to the present invention, the automobile exhaust gas passage, a main monolith catalyst, the honeycomb heater comprising providing at least two electrodes for energizing the honeycomb structure having a large number of through-holes, zeolite With HC as the main component
The adsorbents for adsorbing element (a) are arranged separately from each other, and this can be achieved by a catalytic converter for purifying automobile exhaust gas.

In the present invention, supporting a catalyst on an adsorbent containing high-silica zeolite, or supporting a catalyst on an adsorbent containing zeolite as a main component and / or a honeycomb heater involves the adsorption and catalytic actions of zeolite. Work together to improve exhaust gas purification performance, which is preferable. It is also preferable to coat the honeycomb heater with an adsorbent containing zeolite as a main component or an adsorbent / catalyst composition in which a catalyst component is supported on the adsorbent, as described above.

In the catalytic converter of the present invention, among the main monolithic catalyst, the honeycomb heater, and the adsorbent, the one having the catalyst may be disposed at the most downstream side in the exhaust gas flow path of the automobile. Is not particularly limited. Further, in the honeycomb heater used in the present invention, it is preferable to provide a resistance adjusting mechanism such as a slit between the electrodes because the low-temperature exhaust gas at the time of starting the engine can be quickly heated and heated.

[0010] Zeolite has a Si / Al ratio of 4
It is preferable to use a high silica zeolite of 0 or more because the heat resistance is improved and the application conditions of the catalyst are relaxed. Further, the catalyst loaded on the adsorbent is (a) Pt, Pd, Rh, Ir
And a high silica zeolite having an Si / Al ratio of 40 or more ion-exchanged with at least one noble metal selected from Ru and Ru, and (b) at least one noble metal selected from Pt, Pd, Rh, Ir and Ru It is preferable to use a composition comprising a heat-resistant oxide containing In addition, as the honeycomb structure, it is preferable to use a material obtained by forming a powder material into a honeycomb shape and sintering it.

[0011]

DETAILED DESCRIPTION OF THE INVENTION The present invention, in automobile exhaust gas passage, the honeycomb heater (or catalyst supporting the honeycomb heater, the honeycomb heater of the adsorbent coating, honeycomb heater of the adsorbent-catalyst composition coated), the main monolith catalyst and a zeolite adsorbent ( Or exhaust gas purification for automobiles equipped with a catalyst-supporting adsorbent)
Is a use catalytic converters.

As described above, since the catalytic converter of the present invention has a zeolite adsorbent in addition to the honeycomb heater and the main monolith catalyst, the catalytic converter does not need to be energized before the engine is started, and can be used at the start of the engine driven by the cell motor. The unburned HC in the low-temperature exhaust gas is captured using the adsorption function of zeolite, and then the captured heater starts to desorb at the same time as the honeycomb heater is energized. The HC is preferably purified by reaction because the catalyst on the heater is instantaneously heated. When a catalyst is supported on the zeolite adsorbent, HC is desorbed and purified by reaction.

Since the engine exhaust gas at the start of the engine is on the rich side (oxygen-deficient atmosphere), it is necessary to introduce an oxidizing gas necessary for oxidizing HC and CO, for example, secondary air into the exhaust gas. In the present invention, a honeycomb heater (or a catalyst-carrying honeycomb heater) 2, a main monolith catalyst 3, and a zeolite adsorbent (or a catalyst-carrying adsorbent)
1 (a) to (f) of FIG.

Among these configurations, FIG. 1A is preferable because the zeolite adsorbent 1 is located at the most upstream side of the exhaust gas flow path of the automobile, so that adsorption is easiest. In this case, both the honeycomb heater 2 and the zeolite adsorbent 1 can be used with or without a catalyst. In the configuration of the honeycomb heater 2, the zeolite adsorbent 1, and the main monolith catalyst 3 from the upstream side as shown in FIG. 1 (b), the HC adsorbed on the zeolite adsorbent 1 can be desorbed by energizing the heater 2. Therefore, there is an advantage that control is easy. Also in this case, both the honeycomb heater 2 and the zeolite adsorbent 1 can be used regardless of the presence or absence of the catalyst.

Further, as shown in FIGS. 1 (c) to (f),
When the main monolithic catalyst 3 is installed in the front (most upstream side), the functions of the catalyst on the heater 2 and the zeolite adsorbent 1 are hardly lost, and the durability is preferably excellent. In this case, in the configuration of FIGS. 1C and 1D, both the zeolite adsorbent 1 and the honeycomb heater 2 disposed in the middle can be used regardless of the presence or absence of the catalyst, but are disposed at the most downstream side. Zeolite adsorbent 1 or honeycomb heater 2
It is necessary that a catalyst be supported. On the other hand, FIG.
When the zeolite adsorbent 1 and the honeycomb heater 2 are arranged between the main monolith catalysts 3 as shown in FIG.
Both the honeycomb heater 2 and the zeolite adsorbent 1 can be used with or without a catalyst.

1 (a) to 1 (f), the honeycomb heater 2 may carry a zeolite adsorbent or an adsorbent / catalyst composition in which a zeolite adsorbent carries a catalyst. In this case, the control of adsorption and desorption can be easily performed by energizing the heater. The type of zeolite used as the adsorbent in the present invention is not particularly limited, but may be Y-type, mordenite, or the like, as well as ZSM-5, ZSM-5, commercially available from Mobile and Contec.
8, silicalite (UOP) and the like are preferred. In addition, X-type, Y-type, mordenite and the like obtained by subjecting a zeolite skeleton to dealumination treatment to increase the Si / Al ratio can also be suitably used. Further, it is preferable to use a high silica zeolite having a Si / Al ratio of 40 or more. If the Si / Al ratio is less than 40, the heat resistance becomes insufficient and the hydrophilicity increases, so that the moisture in the exhaust gas is strongly adsorbed, which is not preferable.

In the high silica zeolite, the minimum unit of the crystal unit cell is a crystalline aluminosilicate, similar to a well-known ordinary zeolite, and Al ₂ O ₃ and SiO ₂ are continuously bonded to each other by oxygen ions. However, the Si / Al ratio is as high as about 10 or more as compared with 1 to 5 of ordinary zeolites. In the present invention, as described above, high silica zeolite having a Si / Al ratio of 40 or more is preferable, but from the viewpoint of heat resistance, the Si / Al ratio is more preferably 50 or more, and particularly preferably 60 or more. On the other hand, when the Si / Al ratio exceeds 1000,
When the adsorption capacity itself decreases and when a catalyst component is added, the number of ion exchange sites is reduced, so that only a small amount of noble metal can be ion-exchanged into zeolite, which is not preferable. The high silica zeolite is preferably H (proton) type from the viewpoint of heat resistance.

In the present invention, the catalyst supported on the adsorbent mainly composed of zeolite preferably contains a noble metal such as Pt, Pd or Rh, and further contains a heat-resistant oxide having a high specific surface area. Is preferred in terms of improving the ignition characteristics. Pt, Pd, although noble metals Rh and the like are supported on a zeolite and / or refractory oxide, and the like selective removal capability of heat resistance and NO _X (by-product NH ₃ generation suppression), ion exchange zeolites Is preferably carried.

In view of the above-mentioned catalytic properties and the like, the adsorption / catalyst composition in which a catalyst is supported on an optimal adsorbent in the present invention is (a) at least one selected from Pt, Pd, Rh, Ir and Ru. Si / Al ratio ion-exchanged with one kind of noble metal is 4
Zero or more high silica zeolites and (b) Pt, Pd, Rh, I
and a heat-resistant oxide containing at least one noble metal selected from r and Ru. Here, the component (a) is composed of high silica zeolite and Pt, Pd,
It can be obtained by ion exchange with at least one noble metal selected from Rh, Ir and Ru in a suitable aqueous solution. In order to exhibit the desired performance described above,
The noble metal ion exchange rate is preferably from 10 to 85%,
~ 85% is more preferred.

The noble metal ion-exchanged with the high-silica zeolite is fixed to the zeolite exchange site, has high dispersibility, effectively retains the catalytic activity, is hardly scattered, and does not coagulate even at a high temperature for a long time. High activity over a long period of time. Further, when an adsorbent / catalyst composition in which a catalyst component is supported on an adsorbent is used, coking of HC generated at the time of desorption can be prevented, and the durability of the adsorbent is improved. This noble metal ion exchanged zeolite is produced, for example, as follows. 10 high silica zeolites
Immersed in a solution containing ^-4 to 10 ^-1 mol / l of cationic metal ion, from room temperature to 100 ° C., preferably 80 to 9 ° C.
The noble metal component is ion-exchanged by allowing it to stand, stirred or refluxed at 0 ° C. for about 2 hours or more, and if necessary, filtration and washing are repeated to remove non-ion-exchanged noble metal. After ion exchange, it is usually dried at 80 to 150 ° C., and is further dried at 300 to 1000 ° C. under an oxidation or reduction atmosphere for about 1 hour.
It can be manufactured by firing for 10 to 10 hours.

Further, when an oxide of a rare earth metal such as CeO ₂ or La ₂ O ₃ or an oxide of an alkaline earth metal is added to zeolite, the ternary purification performance due to the oxygen storage capacity of the rare earth metal is expanded, and its application is diversified. It is preferable because the heat resistance can be improved by adding an alkaline earth metal. On the other hand, as the heat-resistant oxide of the component (b), Al ₂ O ₃ , TiO ₂ , Zr
O ₂ , SiO ₂ or a composite oxide thereof can be used. In addition, the addition of oxides of rare earth metals and alkaline earth metals such as CeO ₂ and La ₂ O ₃ to these oxides also increases the three-way purification performance as described above, and also improves the heat resistance. preferable. The component (b) is constituted by supporting at least one of the above-mentioned noble metals on a heat-resistant oxide.

The component weight ratio of component (a) to component (b) is preferably (a) :( b) = 10-85: 90: 15. If the component (a) is less than 10% by weight, it is difficult to selectively remove NO _X (suppress the generation of by-product NH ₃ ), and if it exceeds 85% by weight, the ignition performance becomes poor.
In the adsorption / catalyst composition of the present invention, the total amount of the noble metal supported is preferably in the range of 10 to 35 g / ft ³ and 15 to 30 g / f 3
t ³ is more preferred. When the amount of the noble metal carried is less than 10 g / ft ³ , there is a problem in ignition characteristics and durability, and when it exceeds 35 g / ft ³ , the cost increases. As described above, by using a high silica zeolite having a Si / Al ratio of 40 or more, the catalyst of the present invention can reduce the noble metal Rh by 5%.
g / ft to ³ was necessary to be more supported, 5 g / ft ³
Can also express selective purification performance of the N ₂ sufficiently NO _X in a loading amount less than, more even loading of 0~2g / ft ^3, under relatively mild conditions such as poisoning substance low content at low temperatures When used, practically sufficient selectivity can be exhibited.

Next, the honeycomb structure used in the present invention is preferably manufactured by forming a powdery material into a honeycomb shape and sintering it. In this case, it is preferable to use a so-called powder metallurgy and extrusion molding method. In this case, there is an advantage that the process is simplified and the cost can be reduced. The honeycomb heater used in the present invention has a honeycomb structure made of metal, and the surfaces of the partition walls and pores of the honeycomb structure are covered with a heat-resistant metal oxide such as Al ₂ O ₃ or Cr ₂ O _3. This is preferred because the properties, oxidation resistance and corrosion resistance are improved.

The constituent material of the honeycomb structure is not limited as long as it is made of a material that generates heat when energized.
The material may be metallic or ceramic, but metallic is preferred because of its high mechanical strength. In the case of metal, for example, stainless steel, Fe-Cr-Al, Fe-Cr, Fe-Al, F
Examples thereof include materials made of a material having a composition such as e-Ni, W-Co, and Ni-Cr. Of the above, Fe-Cr-
Al, Fe—Cr, and Fe—Al are preferable because they are excellent in heat resistance, oxidation resistance, and corrosion resistance, and are inexpensive. Further, in the case of metal, a foil type may be used.

The honeycomb structure may be porous or non-porous, but when carrying a catalyst,
The porous honeycomb structure is preferable because the adhesion to the catalyst layer is strong and the catalyst is hardly peeled off due to a difference in thermal expansion. Further, even in the case of a non-porous honeycomb structure, when a resistance adjusting mechanism such as a slit is provided, thermal stress is reduced, and cracks and the like hardly occur. next,
An example of a method for manufacturing a metallic honeycomb structure among the honeycomb structures will be described.

First, for example, F
A metal powder raw material is prepared from e powder, Al powder, Cr powder, or an alloy powder thereof. Then, after mixing the metal powder raw material thus prepared, methyl cellulose, an organic binder such as polyvinyl alcohol, and water,
The mixture is extruded into the desired honeycomb shape. In addition, when mixing the metal powder raw material, the organic binder, and water,
It is preferable to mix an antioxidant such as oleic acid with the metal powder before adding water, or to use a metal powder which has been subjected to a treatment which is not oxidized in advance.

Next, the extruded honeycomb formed body is
It is fired at 1000 to 1400 ° C in a non-oxidizing atmosphere. Here, when firing is performed in a non-oxidizing atmosphere containing hydrogen, the organic binder is decomposed and removed using Fe or the like as a catalyst,
It is preferable because a good sintered body can be obtained. When the firing temperature is lower than 1000 ° C., the molded body does not sinter, and when the firing temperature exceeds 1400 ° C., the obtained sintered body is deformed.
Not preferred.

Preferably, the surfaces of the partition walls and pores of the obtained sintered body are coated with a heat-resistant metal oxide. As a method of coating with the heat-resistant metal oxide, the following method is preferred. 700-1100 metal oxidation honeycomb structure in oxidizing atmosphere
Heat treatment at ℃. Al and the like are plated (for example, vapor phase plating) on the surfaces of the partition walls and pores of the sintered body, and heat-treated at 700 to 1100 ° C. in an oxidizing atmosphere. Dipped in a molten metal such as Al
Heat treatment at 1100 ° C. The surface of the partition walls and pores of the sintered body is coated with alumina sol or the like, and heat-treated at 700 to 1100 ° C. in an oxidizing atmosphere.

The heat treatment temperature is preferably from 900 to 1100 ° C. in terms of heat resistance and oxidation resistance. Next, with respect to the obtained metallic honeycomb structure, it is preferable to provide a resistance adjusting mechanism between the electrodes described later in various modes. As the resistance adjustment mechanism provided in the honeycomb structure,
For example, providing slits in various directions, positions, and lengths, changing the partition wall length in the axial direction of the through-hole, changing the thickness (wall thickness) of the partition walls of the honeycomb structure, or forming cells in the through-hole. Changing the density and providing slits in the ribs of the honeycomb structure are preferable.

The metallic honeycomb structure obtained as described above is usually provided with electrodes by means of brazing, welding, or the like on the partition wall or inside thereof at the outer periphery thereof.
The honeycomb heater according to the present invention is manufactured. The term "electrode" used herein means a general term for terminals for applying a voltage to the honeycomb heater, and includes a terminal directly joined to the outer peripheral portion of the heater and the can body, and a terminal such as ground. This metallic honeycomb structure has an overall resistance value of 0.001Ω.
It is preferable to form it so as to be within the range of 0.5 Ω.

The honeycomb shape of the honeycomb structure of the present invention is not particularly limited, but specifically, for example, 6 to 1500 cells / In ² (0.9 to 233 cells / cm 2).
It is preferable to form the cell so as to have a cell density in the range of ² ). The thickness of the partition walls is preferably in the range of 50 to 2000 μm. In addition, as described above, the honeycomb structure may be porous or non-porous, and the porosity is not limited. It is desirable from the viewpoint of properties and corrosion resistance.
When a catalyst is supported, the catalyst preferably has a porosity of 5% or more from the viewpoint of adhesion to the catalyst.

In the present invention, the honeycomb structure is
It refers to an integrated structure having a large number of through holes separated by partition walls. For example, the cross-sectional shape (cell shape) of the through hole can be any of various shapes such as a circle, a polygon, and a corrugated shape. As the main monolith catalyst used in the catalytic converter of the present invention, conventionally known ones can be used, but a three-way catalyst is preferable. The zeolite adsorbent may have any structure such as beads, pellets, and honeycomb, but preferably has a honeycomb structure in terms of pressure loss. In this case, the honeycomb structure itself may be composed mainly of zeolite, but the adsorbent mainly composed of zeolite is coated on a ceramic or metal substrate having thermal shock resistance. Is more practically preferable.

[0033]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples. (Examples 1 to 8 and Comparative Examples 1 and 2) Selection of zeolite: commercially available Si / Al shown in Table 1
Mordenite zeolite A and ZSM of H type having different ratios
-5 zeolite B to E, zeolite F and Na type Z in which zeolite A is boiled with hydrochloric acid to increase the Si / Al ratio.
SM-5 zeolite G was used. The alkali metal content of zeolite G was 0.85% by weight, and the alkali metal content of other zeolites was 0.1% by weight or less. Here, the BET specific surface area (m ² / g) measured after heating each zeolite at room temperature at 900, 1000 and 1100 ° C. for 5 hours in an electric furnace, respectively, is shown in Table 1. .

[0034]

[Table 1]

As is clear from Table 1, the heat resistance of zeolite depends on the Si / Al ratio. In general, the maximum operating temperature when used as an adsorbent or catalyst for automobile exhaust gas is 1000 ° C. Since the high specific surface area is maintained even at 1000 ° C., it is understood that the zeolite to be used must be a zeolite having a Si / Al ratio larger than 40. Also, zeolite A
As a result of measuring the amount of adsorbed propane / propylene (1/2) at room temperature in the presence of 10% H ₂ O using zeolite A and zeolite B, zeolite B was 1. The 5-fold adsorption amount was large, and zeolite A was strongly poisoned by water.

Preparation of honeycomb heater: average particle size of 10,
20, 22 μm Fe powder, Fe-Al powder (Al 50 wt%
), Using a raw material of Fe-Cr powder (Cr 50 wt%),
The raw materials are blended so as to have a composition of e-22Cr-5Al (% by weight), and an organic binder (methyl cellulose) is added thereto.
And an antioxidant (oleic acid) and water were added to prepare a kneaded material, and a honeycomb consisting of square cells having a rib thickness of 4 mil and a number of through-holes of 400 cells / In ² (cpi ² ) was extruded, dried, and dried. _Two
Firing at 1300 ° C in atmosphere, then 1000 in air
Heat treatment was performed at ℃. The porosity of the obtained honeycomb structure was 22%, and the average pore diameter was 5 μm.

As shown in FIG. 2, two electrodes 11 were set on the outer wall 10 of the honeycomb structure having an outer diameter of 90 mmφ and a length of 25 mm obtained by the above method. Also, as shown in FIG. 2, six slits 12 having a length of 70 mm are provided in the axial direction of the through hole (the slit length at both ends is 50 mm), and the number of cells between the slits 12 is seven (about 10 mm). It was formed so that it might become. Further, the outer peripheral portion 13 of the slit 12 is filled with a zirconia-based heat-resistant inorganic adhesive to form an insulating portion,
A honeycomb heater was manufactured.

Loading of catalyst A on heater: γ-Al ₂ O ₃ .CeO ₂ was deposited on the honeycomb heater obtained above.
(Weight ratio 70:30) and then convert Pt and Rh to Pt / Rh
Was carried at 35 g / ft ³ so that the ratio became 5/1, and the mixture was calcined at 600 ° C., whereby Catalyst A was supported on the heater.

Loading of catalyst B on heater: On the other hand, H-ZS ion-exchanged for Pt was placed on the same honeycomb heater.
M-5 (Si / Al ratio = 48) 50 parts and γ-Al ₂ O _3.
A mixture of 50 parts of CeO ₂ (80:20 by weight) and then converting Pt and Rh to the γ-Al ₂ O ₃ .CeO _2.
The catalyst was impregnated and supported, and finally 35 g / ft ³ of Pt / Rh was provided at a ratio of 19/1, and baked at 600 ° C., thereby coating a catalyst B having a film thickness of 50 μm on the honeycomb heater.

Zeolite adsorbent: A commercially available cordierite honeycomb carrier having a length of 25 mm (manufactured by NGK Insulators, a honeycomb structure composed of square cells having a rib thickness of 6 mil and a through-hole number of 400 cells / In ² ) was used. -ZSM-5 (Si / Al ratio = 48) was coated so as to have a film thickness of 50 μm, and fired at 600 ° C. to produce a zeolite adsorbent.

Loading of catalyst B on zeolite adsorbent: length 25 mm, in the same manner as for loading catalyst B on the heater.
It was coated and supported on a cordierite honeycomb carrier having a thickness of mm.

Loading of adsorbent on heater: A zeolite adsorbent was coated and supported on a honeycomb heater by using the same method as that for preparing a zeolite adsorbent on a cordierite honeycomb carrier.

Main monolith catalyst: Commercial three-way catalyst (ceramic carrier, rib thickness 6 mil, through-hole number 400 cells /
(A honeycomb structure composed of In ² square cells) was used. Using a honeycomb heater, a zeolite adsorbent, and a main monolith catalyst of the types described above, a catalytic converter having these components arranged as shown in Table 2 was evaluated as follows.

That is, in order to confirm the performance at the time of starting the engine, a car having a displacement of 2400 cc was
The Bag1 test on TP was performed. Here, the supply voltage to the heater was 12 V, the energization was started 10 seconds after the engine was started, and the energization was stopped 40 seconds later. During energization, the gas temperature at the center of the heater was controlled to 400 ° C. Also, 200l / min for 50 seconds after starting the engine
Then, secondary air was introduced into the catalytic converter. Table 2 shows the obtained results. On the other hand, for comparison, when the main monolith catalyst alone was used (Comparative Example 1), when the zeolite adsorbent and the main monolith catalyst were used but the honeycomb heater was not used (Comparative Example 2), the same evaluation as above was performed. And the results are shown in Table 2. As is clear from the results in Table 2, according to the catalytic converter of the present invention, HC, C
It is understood that each emission such as O and NO can be satisfactorily purified.

[0045]

[Table 2]

[0046]

As described above, according to the adsorbent of the present invention, since it is a high silica zeolite, the adsorbent is excellent in heat resistance, the application conditions of the catalyst are relaxed, and it can be suitably used for purifying automobile exhaust gas. . Further, according to the present invention, the emission effect of zeolite and the effect of energizing and heating the heater greatly improve each emission in exhaust gas, particularly the purification of HC and CO, and significantly reduce the amount of emission to the atmosphere. it can. Further, in the catalytic converter of the present invention, the arrangement of the zeolite adsorbent, the heater, and the main monolith catalyst can be performed in an optimal manner in consideration of the type of exhaust gas, the purpose of purification, the life of the catalyst, and the like.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a preferred arrangement and configuration of a catalytic converter in the present invention.

FIG. 2 is an explanatory view showing one embodiment of the honeycomb heater of the present invention.

[Explanation of symbols]

1 zeolite adsorbent, 2 honeycomb heater, 3 main monolithic catalyst, 10 outer wall, 11 electrodes, 12 slits, 13 slits outer periphery

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B01J 35/02 F01N 3/02 301E F01N 3/02 301 3/20 H 3/20 3/24 E 3/24 L 3/28 M3 / 28 B01D 53 / 36G (56) References JP-A-1-130735 (JP, A) JP-A-1-135540 (JP, A) JP-A-62-28252 (JP, A) JP-A-6-38225 4-118916 (JP, A) JP-A-3-221127 (JP, A) JP-A-4-293519 (JP, A) JP-A-2-75327 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B01J 20/00-20/34 B01D 53/34 B01D 53/38-53/96

Claims (10)

(57) [Claims] 1. A honeycomb heater in which a main monolith catalyst and at least two electrodes for energizing a honeycomb structure having a large number of through holes are provided in an automobile exhaust gas flow path.
And adsorbs HC (hydrocarbon) with zeolite as the main component
A catalytic converter for purifying automobile exhaust gas , wherein the adsorbents to be treated are separately arranged. 2. Zeolite as a main component, and HC (hydrocarbon)
Automotive exhaust gas purifying catalytic converter according to claim 1, wherein supporting a catalyst on the adsorbent to adsorb iodine). 3. A honeycomb heater according to claim 1 or 2 automotive exhaust gas purifying catalyst converter according obtained by supporting a catalyst on. 4. A honeycomb heater, the zeolite as a main component, HC (hydrocarbons) according to claim 1 or 2 automotive exhaust gas purifying catalyst converter according to the catalyst component was supported on the adsorbent or adsorbing material adsorbs . Wherein said main monolithic catalyst, among the honeycomb heater and the adsorbent, according to any one of claims 1 to those having a catalyst is disposed such that the most downstream side in the automobile exhaust gas passage
5. The catalytic converter for purifying automobile exhaust gas according to any one of the items 4 to 4 . 6. automobile exhaust gas purifying catalyst converter according to any one of the resistance adjusting claims 1 to 5 mechanism to provided between honeycomb heater electrodes. As 7. zeolite, any one of claims 1 to 6, Si / Al ratio using a high-silica zeolite of 48 or more
2. The catalytic converter for purifying automobile exhaust gas according to claim 1 . 8. A catalyst in which an adsorbent has a catalyst supported thereon is obtained by (a) P
t, Pd, Rh, Ir and at least one metal selected from the group consisting of high silica zeolite ion-exchanged with a Si / Al ratio of 48 or more, and (b) selected from Pt, Pd, Rh, Ir and Ru at least one metal is a composition comprising a heat-resistant oxide containing, automobile exhaust gas purifying catalyst converter according to any one of claims 2-7 being. 9. honeycomb structure, automobile exhaust gas purifying catalytic converter according to any one of claims 1 to 8 powdery material is obtained by molding and sintering a honeycomb. 10. The resistance adjusting mechanism is a slit.
Automotive exhaust gas purifying catalytic converter according to any one of 6-9.