JPH04363119A - Exhaust gas purifying material and method for purifying exhaust gas - Google Patents

Abstract

PURPOSE:To obtain an exhaust gas purifying material which can wall remove NOX by making the particulates and hydrocarbon in exhaust gas contg. particulates, hydrocarbon and NOX act as reducing agents and reducing the NOX. CONSTITUTION:A catalyst is supported on a porous ceramic layer formed on a heat resistant porous filter to obtain an exhaust gas purifying material. The catalyst consists of an alkali metal, one or more among Cu, Co, Mn and V a rare earth element. The amt. of the ceramic layer is 3-15wt.% of the amt. of the filter. The amt. of the catalyst is 2.0-7.0wt.% of the amt. of the ceramic layer.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to an exhaust gas purifying material and an exhaust gas purifying method using this exhaust gas purifying material, and more specifically to nitrogen oxides (
The present invention relates to an exhaust gas purification material that can reduce and remove NOx (hereinafter referred to as NOx) with hydrocarbons and particulate carbon substances (hereinafter referred to as particulates), and an exhaust gas purification method using the exhaust gas purification material.

0002

[Prior art and problems to be solved by the invention] In recent years,
Particulate carbon substances (mainly composed of solid carbon particles, called particulates), NOx, etc. in exhaust gas emitted from diesel engines and the like have become a problem as harmful to environmental health. In particular, particulates have an average particle size of 0.1 to 1 μm and are easily suspended in the air, so they are easily taken into the human body through breathing, and recent clinical test results indicate that they also contain carcinogenic substances. This has been confirmed.

[0003] As methods for removing particulates, the following two methods are being considered. One method is to capture particulates by filtering exhaust gas using a heat-resistant filter, and when the resulting pressure loss increases, the filter is regenerated by burning the captured particulates with a burner, electric heater, etc. It is. Heat-resistant filters that can be used include honeycomb ceramic filters, foam ceramic filters with a three-dimensional network structure, steel wool, wire mesh, and the like. The other method is to filter particulates and self-combust them using the action of a catalyst supported on a filter as described above.

In the former case, the higher the particulate removal effect, the faster the rise in pressure loss, the higher the frequency of regeneration, the higher the reliability of regeneration is required, and it is considered to be economically disadvantageous. On the other hand, the latter method is considered to be a much better method if there is a catalyst that can maintain catalytic activity under the exhaust gas emission conditions (gas composition and temperature) of a diesel engine.

However, since diesel engines use light oil as fuel, the exhaust gas contains a large amount of SO2, and the oxygen concentration in the exhaust gas varies over a wide range of 2 to 20% depending on the operating conditions of the diesel engine. Under such exhaust gas conditions, a method for regenerating an exhaust gas purification filter that satisfactorily ignites and burns the accumulated particulates and does not cause secondary pollution has not yet been established. For example, catalysts that have been proposed to purify particulates in exhaust gas from diesel engines include those based on noble metals and base metals. Hydrocarbon (hereinafter referred to as HC)
Although it has high oxidizing properties such as (referred to as ), it is easy to convert SO2 present in exhaust gas into SO3, and there is a high possibility that it will cause secondary pollution. It also has the disadvantage of deteriorating the combustion characteristics of soot. On the other hand, base metal catalysts are effective as particulate purification catalysts, but have problems in terms of durability.

[0006] Furthermore, most of the exhaust gas purification catalysts and purification materials that have been proposed so far have focused on lowering the ignition temperature of particulates, and the oxygen concentration in the exhaust gas is generally high or the oxygen concentration is low. In exhaust gas from diesel engines, etc., which fluctuates greatly, the N contained in it
Ox removal remains an open question.

[0007] Therefore, the present applicant first formed a porous ceramic layer on a porous filter, and added an alkali element, a specific transition metal element, and
A patent application was filed for an exhaust gas purification material that supports a catalyst made of rare earth elements (Japanese Patent Application No. 2-270200).
. In this exhaust gas purification material, Cu is used as a transition metal element.
element and V element are selected, but if the above exhaust gas purification material is used, NOx can be effectively reduced by using particulates in the exhaust gas as a reducing agent, and NOx
Its purifying ability is also extremely long-lasting. However, according to the research conducted by the present inventors, in the case of exhaust gas that contains relatively large amounts of hydrocarbons such as ethylene and propylene in addition to particulates and NOx, it is possible to simply use a catalyst consisting of the above-mentioned components. It was found that the NOx purification rate by HC did not improve much when using HC.

[0008] Therefore, an object of the present invention is to effectively act on exhaust gas in which particulates, hydrocarbons, and NOx are mixed, and to reduce NOx by making the particulates and hydrocarbons act as a reducing agent. An object of the present invention is to provide an exhaust gas purification material and an exhaust gas purification method that can effectively remove these substances.

[0009]

[Means for Solving the Problems] As a result of intensive research into the purification of exhaust gas with a composition in which particulates, hydrocarbons, and NOx are mixed, the present inventors have found that, basically, alkali metal elements and A catalyst system consisting of a specific transition metal element and a rare earth metal element is effective, but when a relatively large amount of hydrocarbons is present in the exhaust gas, reducing the amount of catalyst may actually improve the NOx removal rate. improve,
They also discovered that the regeneration temperature of the filter could be kept low, and completed the present invention.

That is, in the exhaust gas purifying material of the present invention in which a catalyst is supported on a porous ceramic layer provided on a heat-resistant porous filter, the catalyst comprises (a) an alkali metal element, and (b) Cu, Co , Mn, and V; and (c) a rare earth element; the porous ceramic layer accounts for 3 to 15% by weight of the filter; The catalyst is characterized in that it accounts for 2.0 to 7.0% by weight of the porous ceramic layer.

Furthermore, the exhaust gas purification method of the present invention is characterized in that nitrogen oxides are reduced by using a catalyst supported on the filter to mainly make particulates and hydrocarbons act as reducing agents.

The present invention will be explained in detail below. The filters that serve as the base material for exhaust gas purification materials are porous, heat resistant,
In particular, use one with high thermal shock resistance. Further, it is necessary that the pressure loss is within an allowable range and that particulate collection performance is maintained. Such filter forming materials include alumina, silica, titania, zirconia, silica-alumina, alumina-zirconia, alumina-titania, silica-titania, silica-zirconia,
Examples include ceramics such as titania-zirconia, mullite, and cordierite.

[0013] As the filter, a known honeycomb type or foam type filter can be used. The shape and size of the filter can be changed in various ways depending on the purpose, but when using a foam type filter, it is generally formed into a cylindrical shape, with a diameter of 30 to 400 mm and a thickness of 50 mm. ~
Preferably, the length is 300 mm. Also, if necessary,
A plurality of sheets may be stacked. In addition, in the case of foam-type filters, the porosity is 40-80% and the average pore size is 20%.
It is preferably about 0 to 400 μm.

The catalysts supported on the above filter via the porous ceramic layer include (a) alkali metals (Li, Na, K, Cs, etc.), and (b) Cu, C.
one or more elements selected from o, Mn, and V, and (c) rare earth elements (Ce, La, Nd, Sm, etc.)
Use something consisting of. (a) As the alkali metal, it is particularly preferable to use at least one of sodium, potassium, and cesium. Among them, when cesium is used, many unburned HCs, including saturated hydrocarbons such as propane, also react with NOx, resulting in very good NOx removal. This is thought to be because the presence of cesium increases the selectivity of the reaction between NOx and hydrocarbons, suppressing the reaction between oxygen in the exhaust gas and hydrocarbons. In addition, as the component (b), at least one of the four transition elements Cu, Co, Mn, and V is used as described above, but in particular, V
The element (b) is an essential component in the component, and Cu is added to this.
, Co, and Mn, the initial characteristics of the catalyst cannot be expected to be significantly improved, but stable NOx removal over a long period of time can be obtained. Further, as the rare earth metal (c), it is preferable to use cerium, lanthanum, neodymium, etc., and misch metal, which is a mixture of these rare earth metals, can also be used.

The amounts of each of the above catalyst components (a), (b) and (c) are determined by the weight ratio of each metal component.
a) 5-50%, (b) 30-80%, (c)
is preferably 5 to 50%. In particular, when selecting at least one of Cu, Co, and Mn and V as (b), the ratio of the metal element other than V to the V element is about 5/1 to 1/15 by weight. It is better to Alkali metal content is less than 5% by weight, or 50% by weight
If it exceeds % by weight, the simultaneous removal of particulates and NOx will be degraded. In addition, the component (b) is 30% by weight.
If it is less than 80% by weight, the ignition characteristics of particulates will deteriorate, while if it exceeds 80% by weight, the NOx reduction characteristics by HC will deteriorate. Further, when selecting V, if the ratio of the metal element other than V to the V element exceeds 5/1, the sulfur resistance property will decrease, and if it is less than 1/15, the simultaneous removal property will decrease. Furthermore, if component (c) is less than 5% by weight or more than 50% by weight, the simultaneous removal of NOx and particulates will be degraded. The preferred composition range is 10 to 30% of (a)
, (b) is 40-70%, and (c) is 10-30%.

[0016] By using an exhaust gas purifying material having a catalyst configured as described above, it is possible to ignite and burn particulates in the exhaust gas at a relatively low temperature, and also to reduce NO.
x can be effectively removed. In other words, the particulates in the exhaust gas coexist with the catalyst elements and oxygen in the filter, lowering the ignition temperature, and the particulates burn at around 400°C or lower (
oxidized). At the same time, the particulates and HC act as reducing agents to reduce NOx, thereby effectively purifying the exhaust gas. In this way, NOx reduction occurs efficiently at relatively low temperatures because of the particulates and HC in the exhaust gas and the catalyst components (a) and (b).
This seems to be due to the synergistic effect caused by the simultaneous presence of (c) and (c).

[0017] By the way, exhaust gas from a diesel engine or the like normally contains about 100 to 500 ppm of unburned HC, but this HC includes propane, propylene,
Contains acetylene, ethylene, etc. In the catalysts proposed so far in which Cu exists alone as a catalytically active species (for example, JP-A-63-100919), unburned HC has unsaturated bonds such as propylene and acetylene. In some cases, this HC is used as a reducing agent to reduce NOx.
However, the reaction activity using saturated hydrocarbons such as propane as a reducing agent is low, and the
Reductive removal of Ox cannot be said to be sufficient. however,
By using a catalyst with the composition described above, it becomes possible to efficiently reduce NOx even with saturated hydrocarbons such as propane as a reducing agent, resulting in significantly superior NOx purification compared to conventional catalysts. It can be performed.

The above catalyst is supported on the heat-resistant porous filter after a carrier layer made of ceramics which is more porous and has a larger surface area than the filter is formed on the filter. As the material for forming the carrier layer, porous ceramics having a large surface area such as titania, alumina, zirconia, magnesia, titania-alumina, titania-silica, silica-zirconia, and alumina-silica are used. Especially with particulates, HC, and N.
When increasing the reactivity of Ox, zirconia, titania, alumina, titania-zirconia, or alumina-
The carrier layer is preferably made of zirconia.

[0019] The amount of carrier layer is, in the case of ceramic filters, between 3 and 15% by weight of the filter, preferably between 5 and 12%. In addition, catalytically active species ((a) to (c) described above)
) components), the total of which is 2.0 to 7.
0% by weight. If the amount of catalyst supported is less than 2.0% by weight based on the carrier layer, the effect of supporting the catalyst will not be significant, and the ability to simultaneously purify particulates and NOx will decrease. On the other hand, if the supported amount of catalyst exceeds 7.0% by weight, the removal rate of NOx by HC will decrease, so the upper limit is set to 7.0% by weight. Preferably, the amount of catalytically active species is 2.0 with respect to the support layer.
~5.0% by weight. Generally speaking, in order to improve the combustion characteristics of soot (particulates), it is better to increase the amount of catalytic active species, and to increase the reactivity of HC and NOx, it is better to use a smaller amount of catalytic active species. Therefore, it is preferable to adjust the supported amount of catalyst appropriately within the above-mentioned range in consideration of engine characteristics (exhaust gas components), etc.

[0020] The carrier layer made of ceramics can be formed by a wash coat method, a sol-gel method, or the like. The wash coat method is a method in which a carrier layer is formed on the filter by immersing the filter in the above-mentioned porous ceramic slurry and drying it.

[0021] Furthermore, the formation of the carrier layer by the sol-gel method is carried out as follows. The organic salt of the metal (e.g. alkoxide) that forms the ceramic for the carrier layer is hydrolyzed, the resulting sol is coated on a filter, a film of colloidal particles is generated by contact with water vapor, etc., and then dried and fired. to form a catalyst carrier layer on the filter. For example, when titania (TiO2) is used as the ceramic for the carrier layer, first a Ti alkoxide (e.g., Ti(O-
CH
3. A coating liquid is produced by adding acids such as COOH, HNO3, and HCl. After immersing the filter in this coating liquid and pulling it out, it is reacted with steam or water to form a gel. Next, when the filter is dried and fired, a titania film is formed on the pore surface of the filter. In the sol-gel method, an acid is added as a catalyst for the hydrolysis reaction during gelation, but the hydrolysis reaction can also be promoted by adding an alkali instead of the acid.

Although titania has been described above as an example of the ceramic for the carrier layer, other ceramics can be similarly supported by the sol-gel method. For example, when forming an alumina carrier layer, aluminum alkoxide is used in the same manner as in the case of titania described above. The same applies when using other porous carriers.

After forming a porous carrier layer made of ceramics on the filter by the above-mentioned wash coat method or sol-gel method, next, catalytically active species such as carbonate, nitrate, acetate, hydroxide, etc. The carrier layer is impregnated with an aqueous solution of , dried and calcined again to support the catalyst. In addition, as salts of catalytically active metal species, as long as they are soluble in water,
As mentioned above, any type of salt such as carbonate, nitrate, acetate, hydroxide, etc. can be used. For supporting V, a solution of NH4VO3 and oxalic acid can be used. Furthermore, an alkali metal and V can be simultaneously supported using an alkali vanadate.

In the method of the present invention, NOx in the exhaust gas is reduced and removed using HC and particulates using the above-mentioned exhaust gas purifying material. However, since HC in the exhaust gas mainly consists of methane, ethylene, acetylene, etc.
Reduction temperature is 200-500℃, preferably 250-45℃
The temperature shall be 0°C. If the reaction temperature is too high, combustion of HC itself will occur, reducing the NOx reduction properties. In addition, in the method of the present invention, if there is little HC in the exhaust gas that acts as a reducing agent, it is also possible to forcibly introduce HC such as ethylene, propane, propylene, etc. in an amount necessary and sufficient to reduce NOx. It is.

[0025]

EXAMPLES The present invention will be explained in more detail with reference to the following specific examples. Example 1 Cordierite ceramic foam (apparent volume 2
The filter was coated with 10% (weight %, same hereinafter) of TiO2 by wash coating method. To the obtained filter, C
uCl2, La(NO3)3 and CsNO3
TiO2 was impregnated with 1% of these compounds in terms of Cu, La, and Cs, respectively, using an aqueous solution of . After drying, the mixture was fired at 700° C. to obtain a purifying material. Note that in this purifying material, the metal components Cu, La, and Cs exist as oxides.

[0026] Regarding this purifying material, the displacement is 510 cc.
Using a diesel engine, the temperature at which particulates ignite and burn and the filter is regenerated (temperature at which pressure loss decreases) and the NOx conversion rate at that time were determined. The engine was operated at a rotational speed of 1500 rpm and a load of 90%. Under these operating conditions, the total amount of HC in the exhaust gas is 150 ppm of all hydrocarbons, and the amount of CO is 460 ppm.
NOx was 480 ppm, O2 was 10%, and S
O2 was 200 ppm. The results are shown in Table 1.

Examples 2 to 12 A foam filter was coated with 10% TiO2 in the same manner as in Example 1, and CuCl2, Ce(NO3)3
Example 1
The material was dried and calcined in the same manner as in Example 2 to obtain a purifying material supporting a catalyst consisting of Cu, Cs and Ce.

Similarly, CuCl2, La(NO3)
Using each of the aqueous solutions of TiO2 and KCl, a purifying material was obtained in which Cu, La, and K were each supported at 1% relative to TiO2 (Example 3).

Furthermore, CuCl2, Ce(NO3)
3, and using KCl aqueous solution, Cu, Ce and K
A purification material carrying 1% of each was obtained (Example 4).

Furthermore, in place of CuCl2, Co
A purifying material having the following catalytically active species was prepared in the same manner as in Example 1 or 2 using Cl2 or manganese acetate. In addition, in Example 5, the porous ceramic layer (catalyst supporting layer) provided on the filter was made of Al2O3,
In Example 6, Al2O3-ZrO2 was used, in Example 7 ZrO2, in Example 8 TiO2-ZrO2, and in Examples 9 to 12 TiO2 was used. Further, each ceramic layer was 10% of the filter. Furthermore, the amount of each catalytically active species was such that each metal component was 1%. Catalytic active species (ceramic layer) Example 2: Cs/Cu/Ce (TiO2) Example 3:
K/Cu/La(TiO2) Example 4: K/Cu/C
e(TiO2) Example 5: Cs/Co/La(Al2
O3) Example 6: Cs/Co/Ce(Al2O3
-ZrO2) Example 7: K/Co/La(ZrO2
) Example 8: K/Co/Ce(TiO2-ZrO2
) Example 9: Cs/Mn/La (TiO2) Example 10: Cs/Mn/Ce (TiO2) Example 11: K
/Mn/La(TiO2) Example 12: K/Mn/C
e(TiO2)

For each of the obtained purifying materials, the regeneration temperature and NOx purification rate were determined in the same manner as in Example 1. The results are shown in Table 1.

Comparative Example 1 Using the same cordierite foam filter as in Example 1, 10% TiO2 was supported on the filter by the wash coating method. For the obtained filter,
A purification material carrying 1% Cu was prepared using a CuCl2 aqueous solution. The method of supporting Cu element was the same as in Example 1.

[0033] Regarding the obtained purifying material, the regeneration temperature and NOx removal rate were determined in the same manner as in Example 1. The results are shown in Table 1.

[0034]
Table 1 Example No.
Regeneration temperature (℃) NOx purification rate (1)
Example 1 340
50
Example 2 360
40
Example 3 370
35
Example 4 370
35 Example 5 360
45 Example 6
365 35
Example 7
380 30
Example 8
380 30
Example 9 385
40
Example 10 390
35
Example 11 395
30
Example 12 395
30
Comparative example 1 450
20 Table 1 Note (1): NOx purification rate (%) calculated from the amount of NOx in the exhaust gas before and after passing through the filter

As is clear from Table 1, the exhaust gas purification materials of each example have a high NOx purification rate of 30% or more. It can also be seen that the filter regeneration temperature (the temperature at which particulates are ignited and burned) at that time was low, indicating that the exhaust gas was well purified.

Example 13 Cordierite ceramic foam (apparent volume 2
The filter was coated with 10% TiO2 using the wash coat method. The obtained filter was coated with CuCl2, La(NO
3) Cu using an aqueous solution of 3 and CsNO3
, La and Cs were each impregnated with TiO2 at 1%, dried and fired at 700°C. Next, the filter obtained above was immersed in a mixed aqueous solution of NH4 VO3 and oxalic acid to impregnate it with 1% V. After drying this filter, it was fired again at 700°C for 3 hours to obtain a purifying material.

[0037] Regarding this purifying material, the displacement is 510 cc.
Using a diesel engine, the temperature at which particulates ignite and burn and the filter is regenerated (temperature at which pressure loss decreases) and the NOx conversion rate at that time were determined. The regeneration temperature and NOx conversion rate are the same at the beginning of the use of the purifying material (when a decrease in pressure loss is observed for the first time) and at the time when the pressure drop decreases after 10 hours of using the purifying material. It was calculated at two points. The engine was operated at a rotational speed of 1500 rpm and a load of 90%. Under these operating conditions, the total amount of HC in the exhaust gas is 150p of all hydrocarbons.
pm, CO is 460 ppm, NOx is 480 ppm
, O2 10%, and SO2 200 ppm
Met. The results are shown in Table 2.

Examples 14 to 24 In the same manner as in Example 1, Al2O3 (Example 14),
Al2O3-ZrO2 (Example 15), ZrO2
(Example 16), TiO2-ZrO2 (Example 1
7) or TiO2 (Examples 18 to 24) at 10%, and CuCl2, CoC
l2 aqueous solution or manganese acetate aqueous solution, La(NO3
) 3 or Ce(NO3) 3 aqueous solution, KCl
Alternatively, using a CsNO3 aqueous solution and an NH4VO3 aqueous solution, a purification material supporting the catalyst shown below was produced in the same manner as in Example 13. The amount of each metal component supported was 1% for each ceramic layer.

Catalytic active species (ceramic layer) Example 1
4: Cs/Cu/Ce/V (Al2O3) Example 1
5: K/Cu/La/V(Al2O3-ZrO2
) Example 16: K/Cu/Ce/V (ZrO2) Example 17: Cs/Co/La/V (TiO2 -ZrO2
) Example 18: Cs/Co/Ce/V (TiO2)
Example 19: K/Co/La/V (TiO2) Example 20: K/Co/Ce/V (TiO2) Example 21:
Cs/Mn/La/V (TiO2) Example 22: Cs
/Mn/Ce/V (TiO2) Example 23: K/Mn
/La/V(TiO2) Example 24: K/Mn/Ce
/V(TiO2)

For each of the obtained purifying materials, the regeneration temperature and NOx purification rate were determined in the same manner as in Example 13. The results are shown in Table 2.

Comparative Example 2 A cordierite foam filter similar to that in Example 13 was used, and 10% TiO2 was supported on the filter by the wash coating method. For the obtained filter, a purifying material carrying 1% Cu was prepared using a CuCl2 aqueous solution. The method of supporting Cu element was the same as in Example 13.

[0042] Regarding the obtained purifying material, the regeneration temperature and NOx removal rate were determined in the same manner as in Example 13. Table 2 shows the results.
shown according to

[0043]
Table 2
Early (1)
After 10 hours (2) Example No. Regeneration temperature (3) NOx purification rate (4) Regeneration temperature (3) NOx purification rate (4) Example 13
380 40
382 38 Example 1
4 385 35
385 32
Example 15 400 25
403 22
Example 16 400
25 405
22 Example 17 385
30 390
28 Example 18
390 25
395 23 Example 1
9 405 20
408 19
Example 20 405 20
408 18
Example 21 400
30 410
28 Example 22 405
25 415
24 Example 23
410 20
420 18 Example 2
4 410 20
420 18
Comparative example 2 450 20
500 10
Table 2 Note (1): The point at which the first decrease in pressure loss was observed. (2): When the pressure loss decreases 10 hours after gas starts passing through the filter. (3) : Unit is °C (4) : NO in exhaust gas before and after passing through the filter
NOx purification rate (%) calculated from x amount

As is clear from Table 2, Examples 13 to 2
The exhaust gas purification material No. 4 has an extremely good NOx purification rate even after 10 hours of use. Furthermore, the regeneration temperature of the filter (temperature at which particulates are ignited and burned) at that time was also low, indicating that good exhaust gas purification was achieved.

[0045]

[Effects of the Invention] As explained above, by using the exhaust gas purifying material of the present invention, NOx can be efficiently removed. Furthermore, since the purifying material of the present invention contains Cu, Co, Mn, or V as a transition metal in the catalyst, SO2
Even in highly concentrated exhaust gases, NOx, particulates, and HC can be effectively removed simultaneously over a long period of time without degrading the purification properties.

In the purifying material of the present invention, a porous ceramic layer is first formed on a filter by a wash coat method or a sol-gel method, and a catalyst is supported on the ceramic layer. The catalyst is supported at a uniform concentration, resulting in good exhaust gas purification performance.

[0047] The purifying material of the present invention comprises particulates,
It is suitable for purifying exhaust gas containing unburned HC and NOx, and can efficiently purify exhaust gas from diesel engines, etc.

Claims (5)

[Claims] 1. An exhaust gas purifying material comprising a catalyst supported on a porous ceramic layer provided on a heat-resistant porous filter, the catalyst comprising: (a) an alkali metal element; and (b)
The porous ceramic layer is composed of one or more elements selected from the group consisting of Cu, Co, Mn, and V, and (c) a rare earth element, and the porous ceramic layer has 3 to 15 parts of the filter.
% by weight, and the catalyst is 2.0 to 7.0% by weight of the porous ceramic layer. 2. The exhaust gas purifying material according to claim 1, wherein the component (b) of the catalyst comprises V element, Cu, Co
, and one or more elements selected from Mn. 3. The exhaust gas purifying material according to claim 1 or 2, wherein the ceramic layer comprises Al2O3, Al2
O3-based composite oxide, TiO2, ZrO2, Ti
An exhaust gas purifying material characterized by being one of O2-ZrO2. 4. The exhaust gas purifying material according to claim 1, wherein the alkali metal element (a) is Cs. 5. A method of purifying exhaust gas using the exhaust gas purifying material according to any one of claims 1 to 4, comprising:
An exhaust gas purification method characterized in that nitrogen oxides are reduced by causing particulates and hydrocarbons in the exhaust gas to mainly act as reducing agents using a catalyst supported on the filter.