JP2009072740A - Exhaust emission control method and device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an exhaust emission control device and method for an internal combustion engine with enhanced exhaust emission control performance and reduced fuel consumption of the internal combustion engine. <P>SOLUTION: The exhaust emission control device cleans exhaust gas of the internal combustion engine by a nitrogen oxides collection type exhaust gas cleaning catalyst, wherein a sulfur collecting material having a composite oxide with an alkali metal element or an alkaline earth metal element and Ti as the main components is set in an exhaust gas flow passage upstream of the nitrogen oxides collection type exhaust gas cleaning catalyst. An oxidation catalyst oxidizing sulfur to sulfur oxides may be provided in an exhaust gas passage upstream of the sulfur collecting material. By the present invention, sulfur contained in exhaust gas can be efficiently collected and removed, contributing to enhancement of the exhaust gas cleaning performance of the exhaust emission control device and enhancement of durability. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a purification method and a purification device for exhaust gas discharged from an internal combustion engine. In particular, the present invention relates to an exhaust gas purification apparatus provided with a sulfur content capturing material and a nitrogen oxide capturing type exhaust gas purification catalyst in an exhaust passage of an internal combustion engine, and an exhaust gas purification method thereof.

  Lean burn engine or diesel engine has a larger air-fuel ratio than ordinary gasoline engines, and exhaust gas cannot be purified with a three-way catalyst. Therefore, nitrogen oxide trapping type exhaust purification that absorbs and absorbs nitrogen oxides and captures them. A catalyst is used.

  In JP-A-6-336914 (Patent Document 1) and JP-A-2002-47917 (Patent Document 2), when the air-fuel ratio is leaner than the stoichiometric air-fuel ratio, nitrogen oxide is taken in, as in acceleration. A nitrogen oxide trapping type exhaust purification catalyst is disclosed in which when the air-fuel ratio approaches the stoichiometric air-fuel ratio, the captured nitrogen oxide is reduced and released as nitrogen.

  It has been pointed out that such a nitrogen oxide trapping type exhaust purification catalyst is poisoned by sulfur contained in the fuel and causes a decrease in performance. A heavier fuel contains a larger amount of sulfur in the fuel. For this reason, in a diesel engine using light oil as a fuel, the activity of the nitrogen oxide capture type exhaust purification catalyst is likely to decrease compared to an internal combustion engine using gasoline as a fuel.

  In JP-A-6-66129 (Patent Document 3), a sulfur-poisoned nitrogen oxide trapping type exhaust purification catalyst is heated to a high temperature, and the oxygen concentration of the exhaust gas is reduced to set the air-fuel ratio to the stoichiometric air-fuel ratio. It is disclosed that the trapped sulfur is released and regenerated by switching to.

  In Patent Document 1, in order to prevent SOx released when the SOx trapping material is regenerated from being trapped by the NOx trapping material, it flows into the NOx trapping material before the SOx is released from the SOx trapping material. It is described that the oxygen concentration of exhaust gas is reduced.

  Patent Document 2 uses a sulfur component immobilizing agent containing a basic metal element to solidify sulfur before exhaust gas flows into a nitrogen oxide trapping exhaust purification catalyst, It is described that a basic metal is contained in the solidifying agent in an amount larger than an equivalent amount relative to the sulfur content to be solidified.

JP-A-6-336914 (Summary) JP 2002-47917 A (summary) JP-A-6-66129 (summary)

  When regenerating the catalyst by releasing sulfur trapped by the nitrogen oxide trapping type exhaust purification catalyst, the air / fuel ratio is brought close to the stoichiometric air / fuel ratio, so that a large amount of fuel may be consumed, resulting in deterioration of fuel consumption. There is. Moreover, since it is heated to a high temperature, sintering may occur in the noble metal contained in the exhaust purification catalyst, which may reduce the catalytic activity. In the method using the SOx trapping material, SOx released from the SOx trapping material may be trapped by the NOx trapping material, and complicated control is required to prevent it. In the method using the sulfur component solidifying agent, it is necessary to treat the solidifying agent obtained by solidifying the sulfur component.

  Accordingly, an object of the present invention is to provide an exhaust purification method and an exhaust purification device that solve the above-mentioned problems, easily prevent poisoning with sulfur while improving fuel efficiency, and suppress a decrease in the activity of the exhaust purification catalyst. is there.

  A feature of the present invention that solves the above problem is an exhaust gas purifying apparatus for an internal combustion engine having a sulfur trapping material and a nitrogen oxide trapping type exhaust purification catalyst, wherein the sulfur trapping material is an alkaline earth element, an alkali metal It is to contain a complex oxide whose main component is element, titanium. In particular, a composite oxide of an alkaline earth element or an alkali metal element and titanium is preferably included.

  Another feature of the present invention is an exhaust gas purification method for an internal combustion engine that captures sulfur content in exhaust gas using a sulfur content capturing material, and then captures and purifies nitrogen oxides in the exhaust gas. The sulfur content-trapping material contains a complex oxide mainly composed of alkaline earth elements, alkali metal elements, and titanium. It is preferable that the sulfur content capturing material is granulated in the form of particles, or provided as a coat layer on the honeycomb substrate.

In the alkaline earth metal or the composite oxide of alkali metal element and Ti, the molar ratio of Ti and the alkaline earth metal or alkali metal element is preferably 1: 2 to 1: 6. It is desirable that the sulfur trapping material has a pore volume of 0.05 cm ³ or more per gram or a surface area of 10 m ² or more per gram. Due to the large surface area, the ability to capture sulfur can be improved, and the sulfur can be continuously captured for a long time. The sulfur content capturing material includes a void having a diameter of 0.1 to 100 microns for capturing and removing the sulfur content contained in the exhaust gas. By having such a space | gap, the capture | acquisition capability of sulfur content improves, and it can continue capture | acquiring a sulfur content for a long time.

  According to the invention having the above characteristics, the frequency of processing for regenerating the capturing material in which the sulfur content is captured can be reduced, or regeneration processing is not necessary. Therefore, it is not necessary to overheat the catalyst at a high temperature during the regeneration process of the sulfur content trapping material, the activity of the nitrogen oxide capture purification catalyst is reduced, or the fuel ratio is deteriorated by setting the exhaust gas to the stoichiometric air-fuel ratio combustion condition at the time of regeneration. Can be improved.

  According to the present invention described above, it is possible to provide a highly durable exhaust gas purifying apparatus that prevents a decrease in the activity of the nitrogen oxide trapping exhaust purification catalyst. Moreover, the frequency | count of the regeneration process of a sulfur capture | acquisition material can be decreased, and the deterioration of a fuel consumption can be reduced.

  The present invention will be described in further detail. The exhaust purification device of the present invention includes a nitrogen oxide trapping exhaust purification catalyst that removes nitrogen oxides in combustion exhaust gas discharged from an internal combustion engine. The nitrogen oxide capture type exhaust purification catalyst has a problem that it is strongly bonded to a sulfur content such as sulfur oxide and the purification performance of nitrogen oxide is lowered. Moreover, even if the performance of the nitrogen oxide purification catalyst does not deteriorate, it is not desirable to release sulfur oxide into the atmosphere. Therefore, as described above, the sulfur oxide trapping material is disposed on the exhaust flow channel upstream of the nitrogen oxide purification catalyst, and the sulfur content in the exhaust gas discharged from the internal combustion engine is trapped.

  By increasing the sulfur trapping performance of the sulfur trapping material, the number of treatments such as replacement and regeneration of the sulfur trapping material can be reduced. As a result, it is possible to reduce the trouble of replacement and the deterioration of fuel consumption due to the regeneration process. In addition, by reducing the inflow of sulfur content and reducing the number of times the sulfur trapping material is regenerated by high temperature, it is possible to prevent the performance of the nitrogen oxide purification catalyst from being lowered and to maintain the purification performance for a long period of time. .

  The sulfur trapping performance of the sulfur trapping material is improved by using a composite oxide composed of titanium, an alkali metal component, and an alkaline earth component as an active component. In particular, it is preferable that these composite oxides mainly constitute an active component of the sulfur content capturing material. Examples of the alkali metal component include at least one of lithium and potassium, and examples of the alkaline earth metal component include at least one of calcium, strontium, and barium. In addition to the complex oxide having the above basic composition, the sulfur content capturing material is preferably added with an alkali component by mixing or impregnation. The mixing ratio of the alkali metal element or alkaline earth metal element and Ti is preferably 2: 1 to 6: 1 in molar ratio.

It is assumed that the sulfur content in the exhaust gas reacts with the composite oxide of alkali metal, alkaline earth metal and titanium to be captured and fixed as sulfate by the sulfur content capturing material. Therefore, it is preferable to provide an oxidation catalyst on the exhaust flow channel upstream of the sulfur content capturing material. For example, the sulfur content in the exhaust gas can be oxidized to SO ₂ or SO ₃ and can be easily captured by the sulfur content capturing material. The decomposition temperature of the sulfate produced by the reaction between the composite oxide and the sulfur content is higher than the exhaust temperature of a normal internal combustion engine. Therefore, the produced sulfate is stable, and the desorption of the sulfur content hardly occurs in the normal operating state of the internal combustion engine. Therefore, in a normal operation state of the internal combustion engine, sulfur content is not released from the sulfur content trapping material, and the nitrogen oxide purification catalyst is not poisoned by the released sulfur content.

  The exhaust purification device of the present invention is suitable as an exhaust purification device for an internal combustion engine such as a lean burn engine or a diesel engine. The exhaust gas discharged from the diesel engine contains particulates such as dust. These fine particles may cause clogging of the sulfur content capturing material and the nitrogen oxide purification catalyst, which may reduce exhaust purification performance. Accordingly, it is preferable to remove fine particles by installing a fine particle removal filter upstream of the sulfur content capturing material. Moreover, the particulate matter removal filter can be coated or filled with a sulfur content trapping material and provided as a single unit. By integrating, it becomes possible to simplify the structure of the exhaust emission control device.

The sulfur content trapping material is used after being granulated in the form of particles, or adhered to a substrate such as a honeycomb as a coat layer to form a honeycomb coat catalyst. The sulfur-capturing material is mixed with a powder raw material and fired, and then granulated into particles or adjusted as a honeycomb coating layer. Further, it may be produced by supporting a composite oxide as an active component on another porous carrier or the like. In order to easily capture the sulfur content contained in the exhaust gas, the particles and the coating layer are preferably porous and have voids. By adding activated carbon or an organic substance to the powder raw material and baking it, void pores can be generated in the sulfur content capturing material. The diameter of the air gap is preferably 0.1 to 100 microns. Due to such voids, the sulfur content in the exhaust gas can be captured efficiently. The pore volume of the voids is preferably 0.05 cm ³ or more per gram of the sulfur capturing material. Further, it is desirable to have a surface area of 5 m ² or more per gram of sulfur content capturing material.

  An example of an internal combustion engine exhaust gas purification apparatus according to the present invention is shown in FIG. The exhaust emission control device of the present embodiment includes an exhaust particulate filter 4 provided with an oxidation catalyst 3 and a sulfur content trapping material in the exhaust passage 2 of the internal combustion engine 1 in order from the upstream side in the exhaust gas flow direction, and a nitrogen oxide trapping type The exhaust purification catalyst is provided.

  Example 1 is an example of a sulfur content capturing material made of a mixed oxide of Ba and Ti produced by mixing activated carbon. FIG. 2 shows a process for preparing a sulfur content trapping material made of a composite oxide of Ba and Ti. In this example, a sulfur content capturing material was prepared by the adjusting step shown in FIG.

  First, the barium acetate reagent 11 was weighed, stirred and mixed 13 in purified water 12, and dissolved. In a barium acetate aqueous solution, titania sol 14 was weighed and added so that the molar ratio of barium to titanium was 1: 1, and dissolved in purified water. Next, a small amount of aqueous ammonia 15 was added. Ammonia water was added in order to generate a hydroxide precipitate by setting the pH of the mixed solution of barium acetate and titania sol to 10. Subsequently, the mixture was evaporated to dryness with stirring and mixing 16. When evaporating to dryness using an automatic heating mortar, the raw material particles undergo surface modification over a long period of time and become a highly reactive raw material. After evaporation to dryness, the solid content was pulverized 18 with an automatic mortar to obtain a powder. Furthermore, it heat-fired 19 in 600 degreeC air | atmosphere, and obtained the predetermined | prescribed component compound. The reason for heating and baking at 600 ° C. is to obtain a uniform composite oxide of barium titanate. Thereafter, the mixture was pulverized 20 to obtain a raw material 21 of a powdery sulfur content capturing material.

  Next, the particulate sulfur content capturing material 31 was prepared. First, the water-soluble binder 22 was previously dissolved in water to prepare a granulating binder. The water-soluble binder 22 is polyvinyl alcohol. Activated carbon was added to the powdery sulfur content capturing material 21 and 21 and 25 were sufficiently stirred and mixed so as to be uniform, and then a granulating binder was further mixed to prepare a slurry. The slurry was prepared so that the weight ratio of the sulfur-capturing material raw material: activated carbon: the binder for granulation was 90:10:63. The slurry was granulated by an extrusion granulator to obtain granulated powder 29. Similar granulation results were obtained with a spray dryer or a tumbling granulator. The granulated powder 29 was heated at 500 ° C. for 1 hour to burn the activated carbon, and then classified 30 with a sieve of 0.5 mm to 0.7 mm to obtain a sized granulated powder 31.

  The produced granulated granulated powder was subjected to a test for measuring the sulfur content capturing performance. Installed in the quartz reaction tube in the order of the oxidation catalyst honeycomb and the honeycomb filled with sulfur trapping material with respect to the gas flow direction, heated to 300 ° C in an electric furnace and circulated the gas containing sulfur for 6 hours did. The gas components are 10 vol% oxygen, 0.2 vol% carbon monoxide, 200 volppm nitric oxide, 150 volppm sulfur dioxide, and the balance nitrogen when dry. Water was added to this so that it might be 3 vol% in terms of gas standard state volume with respect to the total amount of gas. As the sulfur content capturing material, 1 g of DPF (diesel particulate filter) was filled with 180 g of particulate sulfur content capturing material. As the oxidation catalyst, mordenite carrying platinum was used.

After distribution of the sulfur-containing gas, the sulfur-capturing material was pulverized and the sulfur content in the powder was quantified with a sulfur analyzer. As a result, 98% of the sulfur initially added with sulfur dioxide (SO ₂ ) was detected from the sulfur trap. Therefore, at least 98% of the sulfur content was captured by the sulfur content capturing material, and a high sulfur content capturing effect was demonstrated.

  Example 2 is an example of a sulfur content capturing material made of a composite oxide of Sr and Ti produced by mixing activated carbon.

  First, a raw material for the sulfur content capturing material was prepared as follows. That is, strontium acetate and titania sol were weighed so that the molar ratio of strontium and titanium was 2: 1, dissolved in purified water, and then a small amount of aqueous ammonia 15 was added. Subsequently, the mixture was evaporated to dryness with stirring and mixing 16. After moisture was completely removed, the mixture was pulverized in a mortar and fired at 600 ° C. for 1 hour to obtain a powdery sulfur content trapping material.

Activated carbon having an average particle size of 50 microns was weighed and mixed with this powdery sulfur content trapping material so that the powdery sulfur content trapping material: activated carbon weight ratio was 10: 1. Subsequently, the binder for granulation was mixed and granulated by a granulator. The weight ratio of the powdery sulfur content capturing material and the granulating binder was powdery sulfur content capturing material: granulating binder = 100: 60. The particles produced by the granulator were sieved to a size of 0.5 to 0.7 mm and fired at 500 ° C. for 1 hour to obtain a particulate sulfur content trapping material. The particulate sulfur content trapping material finally prepared had a specific surface area per 1 g of 35 m ² and a pore volume per 1 g of 0.5 cm ³ .

Using the granulated powder made of Sr ₂ TiO ₄ produced in the above process as a sulfur content capturing material, the sulfur content capturing performance was measured. The sulfur content capturing performance measurement test was performed in the same manner as in Example 1. After distribution of the sulfur-containing gas, the sulfur-capturing material was pulverized and the sulfur content in the powder was quantified with a sulfur analyzer. As a result, 98% of the sulfur initially added with sulfur dioxide (SO ₂ ) was detected from the sulfur content capturing material, and the effect of capturing the sulfur content by the sulfur content capturing material was demonstrated.

  In Example 3, the performance of the sulfur content capturing material in which the amount of activated carbon was changed and the porosity was changed was confirmed.

A composite oxide having a composition of Sr ₂ TiO ₄ was used as a raw material, and activated carbon having an average particle size of 50 microns was mixed. The mixing amount of the activated carbon was added and mixed so as to be 0 wt%, 5 wt%, 10 wt%, and 20 wt% with respect to the total amount of the sulfur content capturing material raw material powder and the activated carbon. Each of the four types of sulfur-capturing material raw materials with different amounts of activated carbon was mixed with a granulating binder and granulated with a granulator. The weight ratio between the powdery sulfur content-trapping material and the granulating binder was set to powdery sulfur content-trapping material: granulating binder = 100: 60. The particles produced by the granulator were sieved to a size of 0.5 to 0.7 mm and fired at 500 ° C. for 1 hour to obtain a particulate sulfur content trapping material.

  The sulfur trapping performance of the obtained four kinds of sulfur traps was measured in the same manner as in Example 1. FIG. 3 shows the result of obtaining the sulfur content capturing rate from the sulfur content captured by the four types of sulfur content capturing materials after the sulfur content capturing performance test. FIG. 3 shows the result of relative comparison of the sulfur trapping rates of five types of sulfur trapping materials, assuming that the sulfur trapping rate of the sulfur trapping material not containing activated carbon is 1. The sulfur capture rate was highest when the amount of activated carbon added was 10 wt%.

  In Example 4, the performance of the sulfur trapping material was confirmed by changing the particle diameter of the activated carbon and changing the diameter of the voids.

A composite oxide having a composition of Sr ₂ TiO ₄ was used as a raw material, and the activated carbon was added and mixed so that the activated carbon became 10 wt% with respect to the total amount of the sulfur content capturing material raw material powder and the activated carbon. The average particle diameter of the activated carbon was four types of 10 μm, 30 μm, 50 μm and 90 μm. The four types of sulfur-capturing material raw materials were each mixed with a granulating binder and granulated with a granulator. The weight ratio between the powdery sulfur content-trapping material and the granulating binder was set to powdery sulfur content-trapping material: granulating binder = 100: 60. The particles produced by the granulator were sieved to a size of 0.5 to 0.7 mm and fired at 500 ° C. for 1 hour to obtain a particulate sulfur content trapping material.

  When activated carbon burns and disappears when fired at 500 ° C., the activated carbon portion remains as pore voids in the particulate sulfur trapping material obtained by firing. Therefore, the pore diameter of the voids of each sulfur content capturing material is equal to the average particle diameter of the added activated carbon.

  The sulfur trapping performance of the obtained four kinds of sulfur traps was measured in the same manner as in Example 1. FIG. 4 shows the relative relationship between the sulfur trapping rate obtained from the sulfur trapped by the four types of sulfur trapping materials after the sulfur trapping performance test and the pore diameter.

  The sulfur trapping rate of the granular sulfur trapping material (pore diameter 0) to which no activated carbon is added is 1, and the sulfur trapping rate is shown as a relative value. When the pore diameter was 50 μm (the average particle diameter of activated carbon was 50 μm), the sulfur trapping rate showed the maximum value.

  Next, the molar ratio of alkali metal element, alkaline earth metal element and titanium was examined.

  The trapping materials in which the molar ratio of the alkali metal element (barium) and titanium was changed between 1: 1 to 7: 1 were compared for the sulfur content absorption rate. As titanium, titanium having an anatase type crystal structure was used. The amount of activated carbon was 5% of the total weight of the sulfur-capturing material. As a result of comparing each trapping material based on a molar ratio of alkali to titanium of 2: 1, the result shown in FIG. 5 was obtained. The case where the molar ratio of alkali to titanium was 4: 1 showed the highest absorption rate, and the high sulfur content capture rate was shown in the range of molar ratio 2: 1 to 6: 1. Therefore, the molar ratio of alkali metal element to titanium is preferably in the range of 2: 1 to 6: 1.

Next, appropriate ranges were examined for the specific surface area, pore volume, and pore diameter of the sulfur content-trapping material. The specific surface area, pore volume, and pore diameter were adjusted by changing the amount and size of the activated carbon. BaTiO ₃ was used as the sulfur trapping component. The total volume of the pores 0.05cm ³ /g,0.05cm ³ / g or less of those, 0.05 cm ³ / g or more of a plurality of prepared respectively, confirming an average value of the absorption rate of sulfur As a result, those having a porosity of 0.05 cm ³ / g or higher showed a high sulfur content absorption rate (FIG. 6). Accordingly, those having a porosity of 0.05 cm ³ / g or more are preferable. A specific surface area of 2m ² / g or ^{less, 2~5m 2 / g, 5~8m 2} / g, was confirmed by 8m ² / g or more four, absorption of sulfur in specific surface area 5~8m ² / g Increased, and there was almost no change even at 8 m ² / g or more (FIG. 7). Accordingly, the specific surface area is preferably 5 m ² / g or more. In addition, when the pore diameters of 0.01 to 10 μm, 0.01 to 100 μm, 0.1 to 100 μm, and 1 to 1000 μm are compared, the absorption of sulfur content is the highest when 0.1 to 100 μm is used The rate was high (Figure 8).

1 is a configuration diagram of an exhaust purification system for an internal combustion engine according to an embodiment of the present invention. It is the figure which showed the preparation process of a sulfur content trapping material. It is the characteristic figure which showed the relationship between the sulfur content capture | acquisition ratio of a sulfur content capture material, and the amount of activated carbon added at the time of a sulfur content capture material preparation process. It is the characteristic view which showed the relationship between the sulfur content capture | acquisition ratio of a sulfur content capture material, and the average particle diameter of the activated carbon added at the time of a sulfur content capture material preparation process. It is a characteristic view which shows the relationship between the sulfur content capture | acquisition ratio of a sulfur content capture | acquisition material, and the ratio of the alkali component of a sulfur content capture material, and a titanium component. It is a characteristic view which shows the relationship between the pore volume of a sulfur content absorber, and the absorptance average value of a sulfur content capture material. It is a characteristic view which shows the relationship between the specific surface area of a sulfur content absorption material, and the sulfur content capture rate ratio of a sulfur content capture material. It is a characteristic view which shows the relationship between the diameter of the pore in a sulfur content absorption material, and the sulfur content capture rate ratio of a sulfur content capture material.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Exhaust passage 3 Oxidation catalyst 4 Exhaust particulate filter 5 filled with sulfur content capturing material 5 Nitrogen oxide purification catalyst 11 Barium acetate 12 Purified water 13, 16 Stir and mix 14 Titania sol 15 Ammonia water 17 Evaporation to dryness 18, 20 Grinding 19 Firing 21 Sulfur content capturing material 22 Water-soluble binder 23 Activated carbon 24 Granulator 25 Granulating 26 Drying 27 Classification 28 Particulate sulfur content capturing material

Claims (10)

An exhaust purification method for an internal combustion engine that captures sulfur in an exhaust gas of an internal combustion engine with a sulfur capture material and purifies nitrogen oxide in the exhaust gas after capturing the sulfur with a nitrogen oxide capture and purification catalyst,
The exhaust gas purifying method for an internal combustion engine, wherein the sulfur trapping material contains a complex oxide composed of an alkaline earth element or an alkali metal element and Ti. The exhaust gas purification method for an internal combustion engine according to claim 1,
An exhaust gas purification method for an internal combustion engine, wherein the sulfur trapping material is porous having pores, and the sulfur trapping material has a pore volume of 0.05 cm ³ or more per gram. 3. The exhaust gas purification method for an internal combustion engine according to claim 1, wherein the sulfur content trapping material has a surface area of 5 m ² or more per gram.   The exhaust gas purification method for an internal combustion engine according to any one of claims 1 to 3, wherein the sulfur content trapping material is porous having pores, and the diameter of the pores is 0. An exhaust purification method for an internal combustion engine, characterized by being in the range of 1 micron to 100 microns.   5. The exhaust gas purification method for an internal combustion engine according to claim 1, wherein the sulfur content capturing material is granulated in a granular form.   6. The exhaust gas purification method for an internal combustion engine according to claim 1, wherein the sulfur content trapping material is attached as a coat layer on the honeycomb substrate.   7. The exhaust gas purification method for an internal combustion engine according to claim 1, wherein the complex oxide has a molar ratio of alkaline earth metal or alkali metal element to Ti of 2: 1 to 6: 1. An exhaust gas purification method for an internal combustion engine, comprising a complex oxide in the range of. The exhaust gas purification method for an internal combustion engine according to any one of claims 1 to 7,
An exhaust purification method for an internal combustion engine, comprising a step of oxidizing the sulfur content in the exhaust gas before capturing the sulfur content in the exhaust gas with the sulfur content capturing material. Provided in the exhaust flow path of the internal combustion engine, a sulfur content capturing material for capturing sulfur content in the exhaust gas of the internal combustion engine, and a nitrogen oxide in the exhaust gas after capturing the sulfur content, provided on the downstream side of the sulfur content capture material An exhaust gas purification apparatus for an internal combustion engine having a nitrogen oxide capturing and purifying catalyst for purifying gas,
The exhaust gas purifying apparatus for an internal combustion engine, wherein the sulfur trapping material contains a complex oxide composed of an alkaline earth element or an alkali metal element and Ti. The exhaust gas purification apparatus for an internal combustion engine according to claim 9,
The composite oxide has an alkaline earth metal or alkali metal element and Ti molar ratio in the range of 2: 1 to 6: 1.
The sulfur content trapping material is porous having pores, and the pore volume is 0.05 cm ³ or more per gram of sulfur content capturing material, and the surface area is 5 m ² per 1 gram of sulfur content capturing material. An exhaust emission control device for an internal combustion engine characterized by the above.

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