JP3217602B2 - Method for activating catalyst for purifying exhaust gas of internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for activating an exhaust gas purifying catalyst for an internal combustion engine. Specifically, among the harmful components in the exhaust gas of the internal combustion engine, in particular, nitrogen oxides (N
The present invention relates to a method for efficiently removing NOx in exhaust gas of an internal combustion engine by increasing the activity of a catalyst for reducing Ox).

[0002]

2. Description of the Related Art Atmospheric NOx causes photochemical smog and acid rain. The emission of NOx from diesel vehicles, one of the sources of NOx, has become a social problem.
In the future, studies are under way to regulate emissions. Therefore, development of an exhaust gas purifying catalyst is being promoted. Conventionally, a three-way catalyst has been used for purifying exhaust gas of a gasoline engine. In the gasoline engine, almost no oxygen remained in the exhaust gas, and NOx could be efficiently reduced by unburned hydrocarbons and carbon monoxide. However, the exhaust gas of a diesel engine has a large excess of oxygen due to its engine characteristics, and stoichiometrically emits less reducing agents such as hydrocarbons and carbon monoxide than NOx. NOx can hardly be reduced by the original catalyst.

As a catalyst effective for removing NOx in exhaust gas containing a large amount of oxygen, such as diesel engine exhaust gas and gasoline lean burn engine exhaust gas, for example, a catalyst described in JP-A-63-100919 is described. As mentioned, copper-zeolite catalysts have been proposed. However, this catalyst has problems in that it has poor heat resistance and is easily poisoned by sulfur oxides.

Further, a method using platinum as a main catalyst has been proposed, for example, as described in Japanese Patent Application Laid-Open No. 5-137983. However, since such a platinum-containing catalyst has a strong activity of oxidizing SO ₂ , when it is used for treating a diesel engine exhaust gas, the sulfates are increased by oxidizing the SO ₂ , so that the particulate matter in the exhaust gas is increased. There was a problem that it would. Immediately after production, there is a phenomenon that the activity of a catalyst having NOx decomposing ability is reduced in a short period of use. Although the cause is not clear, it is assumed that, for example, the catalyst surface is oxidized and deactivated, and sulfur contained in light oil poisons the catalyst.

As described above, a catalyst capable of effectively removing NOx has not been developed at present.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for activating an exhaust gas purifying catalyst for an internal combustion engine.

[0007] Another object of the present invention is to provide a fuel cell system comprising:
In the method of purifying with a catalyst, the catalyst is activated by supplying a reducing agent into the exhaust gas within a range where the air-fuel ratio in the exhaust gas always keeps the state of excess oxygen, and the NOx in the exhaust gas is efficiently removed. It is to provide a method of purifying.

Here, the state of oxygen excess means that unburned hydrocarbons and the like in the exhaust gas, carbon monoxide and the supplied reducing agent completely react with the oxygen in the exhaust gas and still contain oxygen in the exhaust gas. Refers to the state where remains. When completely oxidized, methane consumes twice the amount of oxygen and carbon monoxide consumes 0.5 times the amount of oxygen. capacity%. If the concentration of carbon monoxide is 300 ppm, if carbon monoxide is completely oxidized, it consumes 150 ppm of oxygen. In order to completely react with the remaining 79850 ppm of oxygen, 3.99% by volume in terms of methane (39925 ppm) )
Is required, and the concentration of the reducing agent such as hydrocarbons contained in the exhaust gas is 39925 pp in terms of methane.
If it is less than m, an oxygen excess state results.

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for purifying NOx in exhaust gas discharged from an internal combustion engine and having an air-fuel ratio that is always in excess of oxygen using a catalyst.
A time period during which the air-fuel ratio in the exhaust gas always keeps the state of excess oxygen, and a period in which the reducing agent is not supplied to the exhaust gas is a reducing agent.
5 to 10,000 times the time for supplying gas into exhaust gas
A catalyst comprising at least one selected from the group consisting of platinum, rhodium, palladium, copper and iron as an active ingredient , wherein the reducing agent is supplied to the exhaust gas periodically. Achieved by the activation method.

The present invention also provides that the concentration of oxygen coexisting when the reducing agent is supplied into the exhaust gas is 2 to 20% of the exhaust gas.
% Of the catalyst, preferably 4 to 20% by volume. The present invention is also the method for activating the catalyst, wherein the reducing agent contains carbon. The present invention further provides the exhaust gas wherein the concentration of the reducing agent is 500 ppm to 10% in terms of methane with respect to the exhaust gas,
The method for activating the catalyst, which is preferably 5000 ppm to 5% . The present invention is also the method for activating the catalyst, wherein the amount of the supplied reducing agent is 0.01 to 3% by weight of the fuel consumption on average. The present invention also provides that the reducing agent is hydrogen,
The method for activating the catalyst, which is a reducing agent including at least one selected from the group consisting of saturated hydrocarbons, unsaturated hydrocarbons, aromatic hydrocarbons, and alcohols. The present invention further provides the method for activating a catalyst, wherein the reducing agent is a reducing agent containing at least one selected from the group consisting of gas oil, kerosene, liquefied petroleum gas, gasoline, methanol and ethanol. The invention also provides
The method for activating a catalyst, wherein the catalytically active component is supported on a refractory three-dimensional structure. The present invention is further the method for activating the catalyst, wherein the exhaust gas is derived from a diesel engine. The present invention is also the method for activating the catalyst, wherein the average THC / NOx ratio of the supplied reducing agent is 0.01 to 3.

Here, THC is the methane-converted capacity concentration (ppm) of the supplied reducing agent, and this and the NOx capacity concentration (ppm) contained in the exhaust gas of the internal combustion engine.
Is the ratio of THC / NOx.

[0012]

In the present invention, the exhaust gas to be subjected to NOx purification is exhaust gas which is discharged from the internal combustion engine and whose air-fuel ratio is always excessive in oxygen. Specifically, it is an exhaust gas from a diesel engine or an exhaust gas from a gasoline engine that is always operated under lean conditions. In the present invention, the NOx decomposing ability of the catalyst can be increased by supplying the reducing agent into the exhaust gas, and the activated state of the catalyst continues for a while even after the supply of the reducing agent is stopped. .

However, the effect of activating the catalyst due to the supply of the reducing agent is lost within a few minutes to several hours, so that the supply of the reducing agent must be performed periodically. In the present invention, the mechanism by which NOx can be decomposed even though the supply of the reducing agent is stopped is not clear, but, for example, when a relatively high concentration of hydrocarbon comes into contact with the catalyst, the catalyst surface is reduced, and It can be presumed that the NOx decomposing ability can be enhanced. However, the activation is temporary, and it is presumed that the catalyst surface is gradually oxidized during the subsequent exposure to the oxygen-exhausted exhaust gas and eventually returns to the state before the catalyst was activated. .

In the present invention, when the same amount of reducing agent is constantly supplied on average, the NOx purification rate is greatly reduced, as is apparent from the examples described later. Reduction or NOx adsorbed on the catalyst
Is not explained by such a mechanism that is reduced by the reducing agent when the reducing agent is supplied. In the present invention,
Since NOx can be decomposed even when the supply of the reducing agent is stopped, when reducing NOx with the conventional reducing agent, the average reducing agent TH is used.
Whereas the C / NOx ratio required a reducing agent in an amount exceeding 3, the present invention efficiently used the average reducing agent THC / NOx ratio of 0.01 to 3 and more preferably 0.01 to 1 even if the ratio was 0.01 to 1. NOx can be purified.

The type of reducing agent supplied in the method of the present invention is not particularly limited, and examples thereof include reducing agents such as hydrogen, saturated hydrocarbons, unsaturated hydrocarbons, aromatic hydrocarbons, alcohols and the like.

The saturated hydrocarbons include those having 1 to 1 carbon atoms.
30, preferably 1 to 20 alkanes. For example, methane, ethane, propane, butane, pentane, hexane, heptane, octane, nonane, decane and the like are mentioned. These saturated hydrocarbons may be linear or branched.

It may be cyclic, such as cyclohexane.

The unsaturated hydrocarbons include those having 2 carbon atoms.
To 30, preferably 2 to 20 alkenes.
For example, ethylene, propylene, butene, butadiene, pentene, pentadiene, hexene,
Hexadiene, hexatriene, heptene, heptadiene, heptatriene, octene, octadiene, octatriene and the like can be mentioned. These unsaturated hydrocarbons may be linear or branched.

As the aromatic hydrocarbon, for example, benzene, toluene, xylene, trimethylbenzene and the like can be mentioned. Examples of the alcohols include alcohols having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms. Examples include methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol and the like. These alcohols may be linear or branched.

The reducing agent to be supplied is preferably gaseous or liquid at room temperature because it is easy to handle. More preferably, light oil, natural gas, liquefied petroleum gas LPG, gasoline,
If a reducing agent such as methanol or ethanol, which is mounted as a fuel for an internal combustion engine, is used, a container dedicated to the reducing agent to be supplied in the present invention is not required, and the merit is great.

In the present invention, the concentration of the reducing agent supplied is
The supply of the reducing agent into the exhaust gas is not particularly limited as long as the state of excess oxygen is maintained.However, if the concentration of the reducing agent is too low, the effect of activating the catalyst cannot be obtained, and the concentration of the reducing agent is too high. However, since there is no effect corresponding thereto, the THC concentration is preferably 500 ppm to 10% by volume, more preferably 5000 ppm to 5% by volume. Here, the THC concentration is a concentration when a reducing agent such as a hydrocarbon is converted into methane.

In the present invention, if the cycle in which the reducing agent is periodically supplied to the exhaust gas is too short with respect to the time in which the reducing agent is supplied into the exhaust gas, the amount of the reducing agent used is undesirably increased. On the other hand, if the cycle of supplying the reducing agent into the exhaust gas is too large with respect to the time of supplying the reducing agent into the exhaust gas, the activated catalyst loses its effect and loses NOx.
Purification efficiency decreases. Therefore, the time during which the reducing agent is not supplied into the exhaust gas is preferably 50 to 10,000 times, more preferably 100 to 1000 times the time during which the reducing agent is supplied into the exhaust gas.

In the present invention, the average amount of the reducing agent supplied is not particularly limited, but supplying a reducing agent exceeding 3% by weight of the fuel consumption is economically disadvantageous. Since an effect of activating the catalyst cannot be obtained with a supply amount of less than% by weight, the average amount of the reducing agent supplied is preferably 0.01 to 3% by weight of the fuel consumption.

In the present invention, the coexisting oxygen concentration is not particularly limited. However, if the oxygen concentration is too high, part of the reducing agent supplied for the purpose of activating the catalyst is undesirably consumed by oxygen. On the other hand, if the oxygen concentration is too low, the effect of activating the catalyst by the periodic supply of the reducing agent is reduced. Therefore, the coexisting oxygen concentration is preferably 2 to 20% by weight, and more preferably 4 to 20% by weight. The oxygen concentration in the exhaust gas can be controlled by changing the ratio of air to fuel in the engine, and the exhaust gas can be controlled by mixing the intake air into the exhaust gas from the engine through a bypass or the like. It is also possible to control the oxygen concentration in the gas.

The catalyst used in the present invention is not particularly limited, but examples of the catalyst include those containing, for example, platinum, rhodium, palladium, copper, iron and the like as active components. These active ingredients may be used alone or in combination of two or more. In addition to these active components, other components may be contained as co-catalysts. There is no particular limitation on the components of the co-catalyst, but examples include alkali metals such as sodium and potassium, alkaline earth metals such as magnesium and calcium, and rare earths such as cerium, yttrium, lanthanum, and praseodymium. . These active components and cocatalysts are usually used by being supported together with a refractory inorganic oxide on a refractory three-dimensional structure.

There is no particular limitation on the amount of the catalyst component to be carried. However, if the amount is too large, it is economically disadvantageous.
On the other hand, if the amount is too small, the effect as a catalyst is reduced.
Accordingly, the loading amount of the catalyst component is preferably 0.1 to 10 g, more preferably 0.1 to 10 g per liter of the catalyst carrier in the case of a noble metal such as platinum, rhodium, and palladium.
2-5 g. For base metals such as copper and iron and other cocatalysts, preferably 1 to 50 per liter of the catalyst carrier.
g, more preferably 2 to 25 g.

The fire-resistant three-dimensional structure is not particularly limited, but examples thereof include ceramic foam, open-flow ceramic honeycomb, wall-flow honeycomb monolith, open-flow metal honeycomb, metal foam, metal mesh, and the like. be able to. There is no particular limitation on the refractory inorganic material, but examples thereof include activated alumina, silica, titania, zirconia and the like. These refractory inorganic oxides are usually used in the form of powder, and may be used alone or as a mixture. Further, a composite oxide obtained by mixing two or more kinds of solutions of cerium, lanthanum, praseodymium, yttrium, aluminum, silicon, titanium, zirconium and the like by a coprecipitation method or the like and using a mixture thereof as a refractory inorganic material. Is also good.

The method for preparing the catalyst used in the present invention is not particularly limited. For example, the catalyst can be prepared by the following method (1) or (2).

(1) The powder of the refractory inorganic oxide is wet-pulverized to form a slurry, and the refractory three-dimensional structure is immersed in the slurry to remove excess slurry.
Dry at 0 ° C., preferably 100-150 ° C., then
Baking at 00 to 850 ° C, preferably 400 to 600 ° C. Next, the refractory three-dimensional structure is immersed in a solution containing a predetermined amount of catalyst to remove excess solution, and
Drying at ~ 250C, preferably 100-150C,
Then 300 to 850 ° C, preferably 400 to 600 ° C
To obtain the desired catalyst.

(2) A refractory inorganic oxide powder is charged into a solution containing a predetermined amount of a catalyst, impregnated with the powder, and slurried.
Bake at 00-600 ° C. The obtained powder is wet-pulverized to form a slurry, the refractory three-dimensional structure is immersed in the slurry, and after removing excess slurry, the temperature is 80 to 250 ° C.
Preferably dried at 100-150 ° C, then 300-
Calcination at 850 ° C, preferably 400 to 600 ° C, gives the desired catalyst.

[0031]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but it is needless to say that the present invention is not limited to the following Examples.

Method for Preparing Catalyst A Titania powder (a) 10 having a specific surface area of 10 m ² / g
0 g, gallium nitrate 54.4 g and calcium nitrate 4
2.2 g was put into an aqueous solution of chloroplatinic acid containing 10.0 g of platinum, mixed well, dried at 150 ° C. for 2 hours, and calcined at 500 ° C. for 1 hour to remove platinum, gallium oxide and calcium oxide. A dispersed and supported titania powder was obtained.

Next, 112 g of this powder, 800 g of the same titania powder as the above-mentioned titania powder (a) and 320 g of alumina having a specific surface area of 145 m ² / g were mixed and wet-pulverized to form a slurry. Cross-sectional area 1
After impregnating a 5.66 inch diameter x 6.00 inch length cylindrical cordierite honeycomb carrier having about 400 open flow gas flow cells per square inch, removing excess slurry, For 2 hours, and then fired at 500 ° C. for 1 hour.

Method for Preparing Catalyst B Zirconia powder 1000 having a specific surface area of 50 m ² / g
g was poured into an aqueous solution containing 372 g of copper nitrate, mixed well, and dried at 150 ° C. for 2 hours.
C. for 1 hour to obtain a zirconia powder carrying copper dispersed therein.

Next, this powder was slurried by wet pulverization. Approximately 4 per square inch of cross-sectional area
5.6 with 00 open flow gas flow cells
After impregnating with a cylindrical cordierite honeycomb carrier having a diameter of 6 inches and a length of 6.00 inches, excess slurry was removed, dried at 150 ° C. for 2 hours, and fired at 500 ° C. for 1 hour.

Evaluation method for NOx purification rate Supercharged direct injection diesel engine (4 cylinders, 2800c
c) Light oil having a sulfur content of 0.05% by weight was used as a fuel.

The catalyst is installed in the exhaust gas pipe from the engine, and the engine speed is set to 2000 rpm. The torque is set so as to reach a predetermined catalyst inlet temperature. After the catalyst inlet temperature is sufficiently stabilized, the reducing agent is periodically supplied. While supplying the catalyst to the catalyst inlet, the NOx concentration in the exhaust gas at the catalyst inlet and the catalyst outlet was measured to obtain the NOx purification rate.

The concentration (THC) of unburned carbon monoxide and hydrocarbons contained in the exhaust gas before the supply of the reducing agent was 350 pp at 300 ° C.
m, THC was 150 ppm, and at 400 ° C., carbon monoxide was 300 ppm and THC was 130 ppm.

Example 1 Using catalyst A, the catalyst inlet temperature was 300 ° C., and light oil was used as the reducing agent. Once every 20 minutes, the reducing agent was supplied to the catalyst inlet for 10 seconds so that the THC concentration in the exhaust gas became 8000 ppm. At this time, the average concentration of the reducing agent is 63 ppm in terms of methane (hereinafter, all concentrations are methane equivalent), the oxygen concentration at the catalyst inlet is 11% by volume, and the N at the catalyst inlet is
The Ox concentration was 400 ppm and the average THC / NOx ratio was 0.1 ppm.
16. The ratio of the reducing agent supply cycle to the reducing agent supply time is 1
20, the reducing agent supply amount relative to the fuel consumption amount was 0.12% by weight, and the average NOx purification rate was 25%.

Example 2 Using catalyst A, the catalyst inlet temperature was 300 ° C., and light oil was used as the reducing agent. Once every 200 minutes, the reducing agent was supplied to the catalyst inlet for 10 seconds so that the THC concentration in the exhaust gas became 8000 ppm. At this time, the average concentration of the reducing agent was 6.3 ppm, the oxygen concentration at the catalyst inlet was 11% by volume, the NOx concentration at the catalyst inlet was 400 ppm, and the average THC / NOx.
The ratio was 0.01, the ratio of the reducing agent supply cycle to the reducing agent supply time was 1200, the amount of the reducing agent supplied to the fuel consumption was 0.01% by weight, and the average NOx purification rate was 10%.

Example 3 Using catalyst A, the catalyst inlet temperature was 300 ° C., and light oil was used as the reducing agent. Once every 20 minutes, the reducing agent was supplied to the catalyst inlet for 10 seconds so that the THC concentration in the exhaust gas became 800 ppm. At this time, the average concentration of the reducing agent is 6.
3 ppm, oxygen concentration at catalyst inlet 11% by volume, NOx concentration at catalyst inlet 400 ppm, average THC / NOx ratio 0.01, ratio of reducing agent supply cycle to reducing agent supply time 120, reduction to fuel consumption The agent supply amount is 0.01
% By weight, and the average NOx purification rate was 9%.

Example 4 Using catalyst A, the catalyst inlet temperature was 300 ° C., and light oil was used as the reducing agent. The reducing agent was supplied to the catalyst inlet once every 20 minutes so that the THC concentration in the exhaust gas became 8000 ppm for 30 seconds. At this time, the average concentration of the reducing agent is 1
89 ppm, oxygen concentration at catalyst inlet 11% by volume, NOx concentration at catalyst inlet 400 ppm, average THC / NOx ratio 0.47, ratio of reducing agent supply cycle to reducing agent supply time 40, reduction to fuel consumption 0.35 agent supply
% By weight, and the average NOx purification rate was 25%.

Example 5 Catalyst A was used, the catalyst inlet temperature was 300 ° C., and light oil was used as the reducing agent. The reducing agent is used once every 6 minutes to reduce T in the exhaust gas.
It was supplied to the catalyst inlet for 30 seconds so that the HC concentration became 8000 ppm. The average concentration of the reducing agent at this time was 63
0 ppm, oxygen concentration at the catalyst inlet is 11% by volume, NOx concentration at the catalyst inlet is 400 ppm, average THC / NOx ratio is 1.58, ratio of reducing agent supply cycle to reducing agent supply time is 12, reduction to fuel consumption The supply amount of the agent was 1.2% by weight, and the average NOx purification rate was 26%.

Example 6 The catalyst B was used, the catalyst inlet temperature was 400 ° C., and light oil was used as the reducing agent. Once every 20 minutes, the reducing agent was supplied to the catalyst inlet for 10 seconds so that the THC concentration in the exhaust gas became 8000 ppm. The average concentration of the reducing agent at this time was 6
3 ppm, oxygen concentration at catalyst inlet 8% by volume, NOx concentration at catalyst inlet 500 ppm, average THC / NOx ratio 0.13, ratio of reducing agent supply cycle to reducing agent supply time 120, reduction to fuel consumption 0.09
% By weight, and the average NOx purification rate was 19%.

Example 7 Catalyst A was used, the catalyst inlet temperature was 300 ° C., and propylene was used as the reducing agent. The reducing agent is added once every 20 minutes so that the THC concentration in the exhaust gas becomes 8000 ppm.
It was fed to the catalyst inlet for 0 seconds. At this time, the average concentration of the reducing agent was 63 ppm, the oxygen concentration at the catalyst inlet was 11% by volume, the NOx concentration at the catalyst inlet was 400 ppm, and the average THC / NO
The x ratio was 0.16, the ratio between the reducing agent supply cycle and the reducing agent supply time was 120, the reducing agent supply amount relative to the fuel consumption was 0.12% by weight, and the average NOx purification rate was 39%.

Comparative Example 1 The procedure was as in Example 1, except that light oil was constantly supplied at a concentration of 63 ppm. As a result, the average NOx purification rate was 1%.

Comparative Example 2 The same operation as in Example 2 was carried out except that the supply time of light oil was changed to 1 second. As a result, the average NOx purification rate was 0%.

Comparative Example 3 Except that gas oil was constantly supplied at a concentration of 630 ppm,
Performed in the same manner as in Example 1. As a result, the average NOx purification rate was 3%.

Comparative Example 4 The same operation as in Example 6 was carried out except that light oil was constantly supplied at a concentration of 63 ppm. As a result, the average NOx purification rate was 1%.

Comparative Example 5 The same procedure as in Example 7 was carried out except that propylene was constantly supplied at a concentration of 63 ppm. As a result, the average NOx purification rate was 5%.

The test results obtained in Examples 1 to 7 and Comparative Examples 1 to 5 are shown in Tables 1 and 2.

[0052]

[Table 1]

[0053]

[Table 2]

[0054]

As described above, the present invention relates to a method for purifying NOx in exhaust gas discharged from an internal combustion engine and always having an excess air-fuel ratio with oxygen using a catalyst. As long as the fuel ratio always keeps excess oxygen,
The time when the reducing agent is not supplied to the exhaust gas
Since the catalyst activation method is characterized in that the reducing agent is periodically supplied to the exhaust gas at a rate of 5 to 10,000 times the supply time to the gas, the catalyst is always used. Thus, even when the air-fuel ratio in the exhaust gas is always in excess of oxygen, NOx in the exhaust gas can be efficiently purified.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-285335 (JP, A) JP-A-6-26328 (JP, A) JP-A-4-349939 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B01D 53/86 F01N 3/08

Claims (10)

(57) [Claims] 1. A method for purifying NOx in exhaust gas discharged from an internal combustion engine and always having an excess air-fuel ratio with oxygen using a catalyst, wherein the air-fuel ratio in the exhaust gas always maintains an excess oxygen state. And supply the reducing agent into the exhaust gas
The time of not supplying the reducing agent to the exhaust gas
Containing at least one selected from the group consisting of platinum, rhodium, palladium, copper and iron as an active ingredient , wherein a reducing agent is periodically supplied to the exhaust gas at a ratio of 10,000 times. A method for activating a catalyst comprising: 2. The catalyst activation method according to claim 1, wherein the concentration of oxygen present when the reducing agent is supplied into the exhaust gas is 2 to 20% by volume of the outside air gas. 3. The method according to claim 1, wherein the reducing agent contains carbon. 4. The method according to claim 1, wherein the concentration of the reducing agent when supplied into the exhaust gas is 500 ppm or less in terms of methane with respect to the exhaust gas.
The method for activating a catalyst according to claim 3, which is 10%. 5. A method for activating a catalyst according to any one of the amount of reducing agent supplied on average fuel consumption of 0.01-3 claims 1-4 by weight. 6. A reducing agent containing at least one selected from the group consisting of hydrogen, saturated hydrocarbons, unsaturated hydrocarbons, aromatic hydrocarbons, and alcohols. A method for activating a catalyst according to any one of claims 1 to 5 . 7. A reducing agent is gas oil, kerosene, liquefied petroleum gas, gasoline, any one of claims 1 to 5 which is a reducing agent, including those of at least one selected from the group consisting of methanol and ethanol A method for activating a catalyst according to any one of the first to third aspects. 8. catalytic active component, according to claim 1-7 activating a catalyst according to any one of made carried on the refractory three-dimensional structure. 9. exhaust gas activation method of the catalyst according to any one of claims 1-8 is derived from the diesel engine. 10. The average THC / N of the supplied reducing agent.
The method for activating a catalyst according to any one of claims 1 to 9 , wherein the ratio of Ox is from 0.01 to 3.