JPH09155199A - Exhaust gas cleaning catalyst - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make both NOx and NH3 to be cleaned simultaneously by causing platinum and copper to be borne by zeolite in an exhaust gas cleaning catalyst for cleaning NOx and NH3 contained in an exhaust gas in an oxidation atmosphere. SOLUTION: A catalytic converter 1 installed in an exhaust gas pipe 3 connected to an internal combustion engine incorporates an exhaust gas cleaning catalyst 2. This exhaust gas cleaning catalyst 2 is provided with zeoilte (platinum/copper zeolite catalyst) as a carrier, bearing platinum Pt and copper Cu through an ion exchange process. The platinum/copper zeolite catalyst 2a is borne, for example, on the surface of a honeycomb-like base material. The zeolite is preferably a silica-rich zeolite such as ZSM-5 type, ferrielite or mordenite. Thus it is possible to perform the oxidation reaction of NH3 at comparatively lower temperature of an inflow exhaust gas because platinum Pt has an efficient oxidizing power even at low temperatures.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an exhaust gas purifying catalyst.

[0002]

2. Description of the Related Art If the air-fuel ratio of the air-fuel mixture in the combustion chamber of each cylinder is called the engine air-fuel ratio, conventionally, a three-way catalyst is arranged in the exhaust gas passage connected to each cylinder and the engine air-fuel ratio of each cylinder is reduced. By controlling the fuel ratio to the stoichiometric air-fuel ratio, nitrogen oxides NO in exhaust gas
An exhaust gas purifying apparatus for a multi-cylinder internal combustion engine is known in which _{X 2} , hydrocarbons HC and carbon monoxide CO are brought into contact with the catalyst to purify these NO _X , HC and CO simultaneously.

On the other hand, in recent years, the fuel consumption rate has been reduced as much as possible.
Is desired, which allows the engine air-fuel ratio to be set.
It is desirable to make it lean. However, the above-mentioned exhaust gas purification
NO when running lean_XCleans up well
There is a problem that you cannot do it. Therefore, a multi-cylinder internal combustion engine
Of the cylinder of the multi-cylinder internal combustion engine.
Rich operation where the engine air-fuel ratio is rich in some of the cylinders
The engine air-fuel ratio is lean in the remaining cylinders.
Operation control means for continuously performing a certain lean operation, and
First exhaust gas passage connected to the cylinder in which the switch operation is performed
And the exhaust gas passage connected to the cylinder where lean operation is performed
And a second exhaust gas passage different from the first exhaust gas passage
And disposed in the first exhaust gas passage,
NO in the exhaust gas flowing inside_XAmmonia NH_Three Strange
NH to convert_Three Production catalyst, NH_Three1st downstream of production catalyst
When the exhaust gas passage and the second exhaust gas passage are joined together,
The flow passage and the first exhaust gas passage which is arranged in the merge passage.
NH flowing in_Three And NO flowing in from the second exhaust gas passage_X
NO by reacting with_XAnd NH_Three At the same time
Exhaust gas purification device equipped with exhaust gas purification catalyst
Have been developed (see Japanese Patent Laid-Open No. 4-365920).
See). In this exhaust gas purification device, as many cylinders as possible
Fuel consumption rate can be obtained by making the lean operation
Is reduced, while rich operation is performed
Exhaust gas from the cylinder is NH_Three NH to produce catalyst_Three Generate a
However, the NO generated in the cylinder in which lean operation is performed_X
And this NH _Three And react with exhaust gas purifying catalyst
By NO_XIs being cleaned well.

[0004]

As the exhaust gas-purifying catalyst, for example, a catalyst in which cobalt Co, copper Cu, nickel Ni, iron Fe or the like is supported on zeolite can be used. However, in these exhaust gas purifying catalysts, NO _X and NH ₃ are simultaneously improved only when the temperature of the exhaust gas flowing into the exhaust gas purifying catalyst, that is, the inflowing exhaust gas temperature is within a certain temperature range, that is, the purifying temperature range. It has been confirmed by the present inventors that purification cannot be performed. However, the inflowing exhaust gas temperature range during actual engine operation is wider than this purification temperature range, and therefore, when the inflowing exhaust gas temperature deviates from the purification temperature range of the exhaust gas purification catalyst, NO _x or NH ₃ can no longer be made good at the same time. There is a point. In order to solve this problem, if a device for cooling or heating the exhaust gas flowing into the exhaust gas purifying catalyst is provided, the inflowing exhaust gas temperature can be maintained within the purifying temperature range of the exhaust gas purifying catalyst, but the configuration becomes complicated. In addition, the cost will increase.

[0005]

In order to solve the above problems, according to the first aspect of the present invention, there is provided an exhaust gas purifying catalyst for purifying nitrogen oxides and ammonia contained in exhaust gas in an oxidizing atmosphere. Thus, there is provided a catalyst for purifying exhaust gas, which comprises a catalyst in which platinum and copper are supported on zeolite.

According to a second aspect of the present invention, in the first aspect, the zeolite further comprises a catalyst in which copper is supported.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Generally, nitrogen oxides NO _x include nitric oxide NO, nitrogen dioxide NO ₂ , and tetranitrogen dioxide N ₂ O.
4, nitrous oxide N ₂ O and the like may be included. In the following, N
The case where O _X is mainly NO or NO ₂ will be described, but the exhaust gas-purifying catalyst of the present invention can also purify other nitrogen oxides.

Referring to FIG. 1, reference numeral 1 denotes a catalytic converter containing an exhaust gas purifying catalyst 2 of the present invention. An exhaust gas pipe 3 is connected to the exhaust gas inflow side of the catalytic converter 1, and the exhaust gas pipe 3 is connected to, for example, an internal combustion engine. On the other hand, an exhaust gas pipe 4 is connected to the exhaust gas outflow side of the catalytic converter 1. In the embodiment shown in FIG. 1, the exhaust gas-purifying catalyst 2 is equipped with a zeolite (referred to as platinum / copper zeolite catalyst) 2a, which is a carrier on which platinum Pt and copper Cu are supported by ion exchange. 2a is carried on the surface of a base material having a honeycomb shape, for example. For zeolite, for example, ZSM-5
High silica content zeolites such as mould, ferrierite and mordenite are used. In this embodiment, the platinum / copper zeolite catalyst 2a is supported on almost the entire base material.

Exhaust gas containing NO _x and ammonia NH ₃ , that is, exhaust gas containing NO _x and NH ₃ at the same time,
Alternatively, when an exhaust gas having an exhaust gas portion containing NO _X without NH ₃ and an exhaust gas portion containing NO ₃ without NO _X alternately contacts the exhaust gas purification catalyst 2 in an oxidizing atmosphere, the exhaust gas purification catalyst 2 Purifies NO _x and NH ₃ , that is, reduces NO _x and N
It oxidizes H ₃ . In addition, NO in the exhaust gas that flows in
_{When X} and NH ₃ are mixed, NH ₃ is oxidized by NO _X in the exhaust gas purifying catalyst 2. Although the purifying mechanism in this case has not been clarified, the following equation (1)-
It is considered to be carried out by the reaction of (4).

4NH ₃ + 7O ₂ → 4NO ₂ + 6H ₂ O (1) 4NH ₃ + 5O ₂ → 4NO + 6H ₂ O (2) 8NH ₃ + 6NO ₂ → 12H ₂ O + 7N ₂ (3) 4NH ₃ + 4NO + O ₂ → 6H ₂ O + 4N ₂ ( and NO _X produced by the oxidation reaction, and NO _X in the exhaust gas flowing into the exhaust gas purifying catalyst 2 is the reduction of formula (1) and (2) in the denitration reaction of 4) (3) and (4) . Therefore, NO _x and NH ₃ are simultaneously purified.

Zeolite is used as N in the inflowing exhaust gas.
It has a function of temporarily adsorbing H ₃ and releasing the adsorbed NH ₃ . Although the NH ₃ absorption / release mechanism of zeolite has not been clarified, the adsorbed NH ₃ is released when the NH ₃ concentration in the inflowing exhaust gas becomes low or when the inflowing exhaust gas contains NO _X. Is believed to be. The released NH ₃ reacts with NO _X in the inflowing exhaust gas to be purified. Therefore, N
Exhaust gas portion containing NO _X without H ₃ and NO _X
If the exhaust gas portion containing NH ₃ is repeatedly alternately contacted with the catalyst 2 for purifying an exhaust gas without containing, catalyst 2 for exhaust gas portion exhaust gas purification containing NH ₃ without including NO _X
The NH ₃ in the exhaust gas is adsorbed on the catalyst 2 for purifying exhaust gas when in contact with, when the exhaust gas portion containing no NO _X include NH ₃ in contact with the catalyst 2 for purifying an exhaust gas is adsorbed on the catalyst 2 for exhaust gas purification Released NH ₃ is released.
The released NH ₃ is purified by the above-described oxidation reactions (1) and (2) in an oxidizing atmosphere, while NO _X in the exhaust gas flowing into the exhaust gas-purifying catalyst 2 is removed by the above-mentioned denitration reaction (3) and Purified by (4).

By the way, the Cu-zeolite catalyst comprising a copper Cu is supported on zeolite by ion exchange, purification action of the NO _X and NH ₃ in the oxidation atmosphere when in contact with the exhaust gas containing NO _X and NH ₃ row Be seen.
However, the temperature of the exhaust gas flowing into the copper zeolite catalyst,
That is, when the inflowing exhaust gas temperature is relatively low, for example, 10
It has been confirmed by the present inventors that it is difficult to simultaneously purify NO _X and NH ₃ satisfactorily at about 0 to 200 ° C. That is, although NO _x can be purified satisfactorily, a large amount of NH ₃ is exhausted from the exhaust gas purification catalyst 2 without being purified. This is because the above-mentioned oxidation reactions (1) and (2) are not satisfactorily performed due to the relatively small oxidizing power of copper Cu at low temperatures, and as a result, NH ₃
It is thought that this is because it cannot oxidize satisfactorily.

On the other hand, when the exhaust gas-purifying catalyst 2 is formed from the platinum-copper zeolite catalyst 2a as in the present embodiment, the inflowing exhaust gas temperature is high because platinum Pt has a good oxidizing power even at low temperatures. The NH ₃ oxidation reaction can be satisfactorily carried out even at a relatively low temperature, and therefore NO _x and NH ₃ can be satisfactorily purified at the same time.

When the exhaust gas containing NH ₃ without containing NO _x is brought into contact with the exhaust gas purifying catalyst 2 composed of the platinum-copper zeolite catalyst 2a, the inflowing exhaust gas temperature is wide, that is, from 100, for example. 500
It has been confirmed by the present inventors that NH ₃ can be satisfactorily purified over a temperature range of about ° C. FIG. 2 shows another embodiment of the exhaust gas purifying catalyst 2 according to the present invention. In this figure, components similar to those of the embodiment of FIG. 1 are designated with the same reference numbers.

In the embodiment shown in FIG. 2, the exhaust gas purifying catalyst 2 comprises a platinum / copper zeolite catalyst 2a and a copper zeolite catalyst 2b which are arranged in series with each other. In this embodiment, the platinum / copper zeolite catalyst 2a and the copper zeolite catalyst 2b are supported on the surface of a common base material. That is, the same platinum / copper zeolite catalyst 2a as the embodiment of FIG. 1 is carried on the surface of the base material portion of the base material located on the exhaust gas downstream side, and the copper zeolite catalyst 2b is located on the exhaust gas upstream side. It is carried on the surface of the part.
The copper zeolite catalyst 2b is formed from high silica-containing zeolite in which copper Cu is supported by ion exchange.

The exhaust gas purifying catalyst 2 of this embodiment is also NO.
_{When the} exhaust gas containing _X and NH ₃ is contacted in an oxidizing atmosphere, NO _X and NH ₃ in the exhaust gas are simultaneously purified. In this case, the exhaust gas purifying action based on the purifying mechanism described above with reference to the formulas (1) to (4) is achieved in each of the platinum / copper zeolite catalyst 2a and the copper zeolite catalyst 2b, or in the exhaust gas purifying catalyst 2 as a whole. It is believed to be done.

As described above, when the exhaust gas purifying catalyst 2 is formed of the platinum / copper zeolite catalyst 2a, NO _x and NH ₃ in the exhaust gas can be simultaneously purified well when the inflowing exhaust gas temperature is relatively low. However, when the temperature of the inflowing exhaust gas becomes high, for example, when it exceeds about 200 ° C, N
Pt / copper zeolite catalyst 2a without purification of O _x
It has been confirmed by the present inventors that they are discharged from This is because when the temperature of the inflowing exhaust gas becomes high, the oxidizing power of platinum Pt becomes too strong and a large amount of NO _x is produced by the above-mentioned oxidation reactions (1) and (2), and as a result, denitration reactions (3) and (4). It is considered that NO _x cannot be purified satisfactorily.

On the other hand, when the exhaust gas purifying catalyst 2 is formed from the platinum-copper zeolite catalyst 2a and the copper zeolite catalyst 2b as in the present embodiment, the exhaust gas flowing into the exhaust gas purifying catalyst 2 has a wide temperature range. That is, for example, NO _x and NH ₃ can be satisfactorily purified simultaneously over a temperature range of about 100 to 500 ° C. This is because platinum provided on the exhaust gas downstream side by providing the copper zeolite catalyst 2b on the exhaust gas upstream side.
It is considered that this is because the amount of NO _X flowing into the copper zeolite catalyst 2a can be made zero or extremely small.
That is, the inflowing exhaust gas does not contain NO _X and is NH
When the platinum-copper zeolite catalyst 2a contains ₃ as described above, the platinum / copper zeolite catalyst 2a has excellent NH ₃ purification characteristics, so that the exhaust gas purification catalyst 2 as a whole has excellent exhaust gas purification characteristics.

Referring again to FIG. 2, in this embodiment, white
The gold / copper zeolite catalyst 2a is placed on the downstream side of the exhaust gas,
Although the zeolite catalyst 2b is arranged on the upstream side of the exhaust gas,
The copper zeolite catalyst 2b is placed on the downstream side of the exhaust gas,
Place the copper zeolite catalyst 2a on the upstream side of the exhaust gas
You can also. However, the embodiment shown in FIG.
Platinum / copper zeolite catalyst 2a under exhaust gas as in
On the flow side, the copper zeolite catalyst 2b is arranged on the upstream side of the exhaust gas.
Preferably. Endurance temperature of platinum / copper zeolite catalyst 2a
The degree is lower than the endurance temperature of the copper zeolite catalyst 2b. one
On the other hand, basically, the exhaust gas downstream is exhausted more efficiently than the exhaust gas upstream.
The temperature of the screen becomes low. Therefore, platinum / copper zeolite contact
The medium 2a is exhausted downstream, and the copper zeolite catalyst 2b is exhausted.
If placed upstream, it will prevent significant deterioration of these catalysts.
Meanwhile, the exhaust gas can be satisfactorily purified. Also, above
As described above, the platinum / copper zeolite catalyst 2a is NO_XIncluding
NH without any problems_Three NH in exhaust gas containing_Three Inflowing exhaust gas
It can be satisfactorily purified over a wide temperature range. did
Therefore, the platinum / copper zeolite catalyst 2a is placed on the exhaust gas downstream side.
If the copper zeolite catalyst 2b is arranged on the upstream side of the exhaust gas,
The temperature of the exhaust gas flowing into the copper zeolite catalyst 2b is low
NO in the copper zeolite catalyst 2b_XAnd NH _Three The ten
Even if it cannot be sufficiently purified, it is a downstream platinum / copper zeolite catalyst 2
Can be satisfactorily purified. Also, for example,
NH flowing into the gas purification catalyst 2_Three The amount will increase significantly
NH released from copper zeolite catalyst 2b_Three Large quantity
Width increases to NH from copper zeolite catalyst 2b_Three Is purified
Platinum / copper zeolite contact
Medium 2a is excellent NH_Three Has a purification capacity, that is,
NH discharged from the copper zeolite catalyst 2b_Three Is platinum
When the exhaust gas flowing into the copper zeolite catalyst 2b is high
Even if it uses platinum / copper zeolite catalyst 2a
Is done. Therefore, it is purified from the exhaust gas-purifying catalyst 2.
NO discharged without_XAnd NH_Three An extremely small amount
You will be able to

FIG. 3 shows another embodiment of the exhaust gas purifying catalyst 2. Also in this embodiment, the exhaust gas-purifying catalyst 2 includes both the platinum / copper zeolite catalyst 2a and the copper zeolite catalyst 2b. However, the platinum / copper zeolite catalyst 2a and the copper zeolite catalyst 2b are supported on different carriers. That is, the platinum / copper zeolite catalyst 2a is arranged in the catalytic converter 1a arranged downstream of the exhaust gas and connected to the exhaust gas pipe 4, and the copper zeolite catalyst 2b is arranged upstream of the exhaust gas and connected to the exhaust gas pipe 3. It is arranged in the catalytic converter 1b. The catalytic converters 1a and 1b are connected to each other by an exhaust gas pipe 5.

Also in the exhaust gas purifying catalyst 2, NO _x and NH ₃ contained in the exhaust gas can be simultaneously purified well. In this case as well, the platinum / copper zeolite catalyst 2a can be placed upstream of the exhaust gas and the copper zeolite catalyst 2b can be placed downstream of the exhaust gas. However, as described above, the platinum / copper zeolite catalyst 2a is placed downstream of the exhaust gas and the copper zeolite catalyst 2b is placed downstream. It is preferably arranged upstream of the exhaust gas.

FIG. 4 shows still another embodiment of the exhaust gas purifying catalyst 2. Also in this embodiment, the exhaust gas-purifying catalyst 2 includes both the platinum / copper zeolite catalyst 2a and the copper zeolite catalyst 2b. However, in the present embodiment, the platinum / copper zeolite catalyst 2a and the copper zeolite catalyst 2b are not connected in series, but these platinum / copper zeolite catalyst 2a and the copper zeolite catalyst 2b are connected.
Are laminated and carried on a carrier. In this case, the platinum / copper zeolite catalyst 2a and the copper zeolite catalyst 2b may be laminated in any manner, but in consideration of the endurance temperature of each catalyst, the platinum / copper zeolite catalyst 2a is first loaded on the base material, It is preferable that the platinum / copper zeolite catalyst 2a is coated by supporting the copper zeolite catalyst 2b on the top. In addition, on the substrate, platinum / copper zeolite catalyst 2a
Alternatively, the copper zeolite catalyst 2b may be supported almost uniformly.

FIG. 5 shows an exhaust gas purifying catalyst 2 according to the present invention,
For example, the case where the exhaust gas-purifying catalyst 2 shown in FIG. 2 is applied to an internal combustion engine is shown. Referring to FIG. 5, the internal combustion engine 6 is connected via an exhaust gas pipe 7 to a three-way catalyst 8 which is an NH ₃ production catalyst, and the three-way catalyst 8 is connected via an exhaust gas pipe 3 to an exhaust gas purifying catalyst 2. . In the internal combustion engine 6, the rich operation in which the air-fuel ratio is richer than the theoretical air-fuel ratio and the lean operation in which the air-fuel ratio is leaner than the theoretical air-fuel ratio are alternately repeated. When the exhaust gas in the rich operation reaches the three-way catalyst 8, NH ₃ is produced in the three-way catalyst 8 from a part of NO _{x in} the exhaust gas. The remaining NO _x is reduced to N ₂ . The NH ₃ produced by the three-way catalyst 8 reaches the exhaust gas purifying catalyst 2 and is adsorbed on the exhaust gas purifying catalyst 2. Therefore, NH ₃ is prevented from being discharged from the exhaust gas purifying catalyst 2.

On the other hand, when lean operation is performed in the internal combustion engine 6 and the exhaust gas at this time reaches the three-way catalyst 8, NO _{X in} this exhaust gas passes through the three-way catalyst 8 without being oxidized or reduced. Next, the exhaust gas purifying catalyst 2 is reached. At this time, the NH ₃ concentration in the exhaust gas is almost zero, and as a result, the adsorbed NH ₃ is released from the exhaust gas purifying catalyst 2. At this time, the surroundings of the exhaust gas purifying catalyst 2 are in an oxidizing atmosphere, and therefore the released NH ₃ is purified in the exhaust gas purifying catalyst 2 together with NO _X in the exhaust gas. That is, NO _x and NH ₃ are prevented from being discharged from the exhaust gas purifying catalyst 2 regardless of whether the internal combustion engine 6 performs rich operation or lean operation.

[0025]

【Example】

Example 1 Platinum / copper zeolite catalyst 2a supported by ion-exchange of 1 wt% platinum and 2.4 wt% copper Cu on ZSM-5 type zeolite of SiO ₂ / Al ₂ O ₃ = 40 (molar ratio). An exhaust gas purifying catalyst 2 was formed (see FIG. 1).

Example 2 The platinum / copper zeolite catalyst 2a of Example 1 was placed on the exhaust gas downstream side of the carrier and Z ₂ / Al ₂ O ₃ = 40 (molar ratio) Z was added.
The copper zeolite catalyst 2b supported by ion-exchange of 2.4% by weight of copper Cu on SM-5 type zeolite,
The platinum / copper zeolite catalyst 2a was supported on the exhaust gas upstream side to form the exhaust gas purifying catalyst 2 (see FIG. 2).

Comparative Example The copper zeolite catalyst 2b of Example 2 was supported on a substrate to form an exhaust gas purifying catalyst.

Test Example 1 Exhaust gas purifying catalysts of Example 1, Example 2 and Comparative Example
A model gas that simulates the exhaust gas with the following composition
NO at the catalyst outlet for exhaust gas purification _Xand
NH_Three The total purification rate is measured by changing the influent gas temperature.
Specified. NH_Three : 100 (ppm) NO_X: 100 (ppm) CO_Two : 15 (%) O_Two : 4 (%) H_Two O: 3 (%) N_Two : Balance The measurement results are shown in FIG. From FIG. 6, (NO_X+ NH
_Three ) In Example 1, the purification rate can be maintained at 80% or more.
Is when the temperature of the inflowing exhaust gas is 100 to 180 ° C.
In Example 2, when the temperature is about 100 to 470 ° C.
In the comparative example, it is found that the temperature is about 160 to 450 ° C.
Call In addition, (NO_X+ NH_Three ) Purification rate of 90% or more
In the first embodiment, the temperature of the inflowing exhaust gas can be maintained at 100.
To about 160 ° C., and in Example 2 100
To about 400 ° C., and 180 to 3 in the comparative example.
It can be seen that the temperature is about 50 ° C. That is, in Example 1,
Is more NO than the comparative example when the inflow exhaust gas temperature is low_XAnd
And NH_Three Can be purified at the same time. Also,
Example 2 compares over a wide range of influent gas temperatures.
NO than the example_XAnd NH_Three At the same time
Can be.

Test Example 2 A model gas simulating exhaust gas having the following composition was brought into contact with the exhaust gas purifying catalysts of Example 1, Example 2 and Comparative Example to measure the NH ₃ purification rate at the exhaust gas purifying catalyst outlet. The temperature of the inflowing exhaust gas was changed and measured. _{NH 3: 100 (ppm) CO} 2: 15 (%) O 2: 4 (%) H 2 O: 3 (%) N 2: balance The measurement results are shown in Figure 7. From FIG. 7, the NH ₃ purification rate can be maintained at 80% or more when the inflowing exhaust gas temperature is about 100 to 500 ° C. in the first embodiment.
It can be seen that is about 100 to 500 ° C. and about 220 to 450 ° C. in the comparative example. Also, N
The H ₃ purification rate can be maintained at 90% or more in Example 1 when the inflowing exhaust gas temperature is about 100 to 500 ° C., in Example 2 about 100 to 500 ° C., and in Comparative Example 240. It can be seen that the temperature is about 400 ° C. That is, in Examples 1 and 2, NH ₃ can be purified better than Comparative Example over a wide temperature range of the inflowing exhaust gas temperature.

[0030]

INDUSTRIAL APPLICABILITY NO _X and NH ₃ contained in exhaust gas
Can be purified at the same time.

[Brief description of the drawings]

FIG. 1 is a diagram showing an exhaust gas purifying catalyst according to an embodiment of the present invention.

FIG. 2 is a diagram showing another embodiment of an exhaust gas purifying catalyst.

FIG. 3 is a view showing still another embodiment of the exhaust gas purifying catalyst.

FIG. 4 is a view showing still another embodiment of the exhaust gas purifying catalyst.

FIG. 5 is an overall view of an internal combustion engine showing a case where the exhaust gas purifying catalyst of the present invention is applied to the internal combustion engine.

FIG. 6 is a diagram showing an experimental result of purification rates of NO _X and NH ₃ .

FIG. 7 is a diagram showing experimental results of NH ₃ purification rate.

[Explanation of symbols]

 2 ... Exhaust gas purifying catalyst 2a ... Platinum / copper zeolite catalyst 2b ... Copper zeolite catalyst 6 ... Internal combustion engine 8 ... Three-way catalyst

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takaaki Ito 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd. (72) Inventor Naoto Suzuki, 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Co., Ltd. (72) Inventor Takaaki Kanazawa 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Corporation (72) Inventor Takahiro Hayashi 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor, Koji Yokota Aichi Inside the Toyota Central Research Institute, 41, Nagatake, Nagakute-cho, Aichi-gun, Japan Inside the Toyota Central Research Institute Co., Ltd. (72) Inventor, Yasutaka Nagai Inside the Toyota Central Research Institute, 41-City, Nagakute-cho, Aichi-gun, Aichi-gun

Claims (2)

[Claims] 1. An exhaust gas purifying catalyst for purifying nitrogen oxides and ammonia contained in an exhaust gas in an oxidizing atmosphere, the exhaust gas purifying catalyst comprising a catalyst comprising platinum and copper supported on zeolite. 2. The exhaust gas purifying catalyst according to claim 1, further comprising a catalyst in which copper is supported on zeolite.