JP2016131918A - Method for producing exhaust gas purification filter, exhaust gas purification filter, and exhaust gas purification device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing an exhaust gas purification filter, in which a catalyst is deposited easily and conveniently on the produced exhaust gas purification filter without impregnating the produced exhaust gas purification filter with a catalyst particle-containing solution or without applying the catalyst particle-containing solution to the produced exhaust gas purification filter so that the exhaust gas purification filter having high NOx reduction efficiency can be obtained.SOLUTION: The method for producing the exhaust gas purification filter comprises the steps of: subjecting a mixture containing zeolite and a raw material particle of a carrier to extrusion molding to produce a molding; sintering the molding to produce a sintered compact; treating the sintered compact with an acid under such a condition that pH is 4.0 or lower; and exchanging an element of the ion exchange site of the zeolite to be contained in the acid-treated sintered compact with a transition metal.SELECTED DRAWING: None

Description

  The present invention relates to an exhaust gas purification filter manufacturing method, an exhaust gas purification filter, and an exhaust gas purification device.

  Exhaust gas discharged from internal combustion engines such as diesel engines contains harmful substances such as particulate matter (PM), nitrogen oxides (NOx), hydrocarbons, carbon monoxide, etc. Various techniques have been used to remove material. In particular, since NOx and PM discharged from diesel vehicles such as trucks and buses contribute to air pollution in urban areas, regulations on these harmful substances are increasingly tightened.

  PM is removed by, for example, a method in which PM is collected in a filter disposed in the exhaust gas flow path, and when the PM is deposited in a predetermined amount, the filter is heated to burn and decompose PM. However, since the combustion temperature of PM is as high as 550 to 650 ° C., there is a problem that the apparatus becomes large and the energy cost for heating increases. In order to burn PM at a lower temperature, a honeycomb filter carrying a catalyst is used. As such a catalyst, Patent Document 1 proposes composite oxide particles containing Si and Zr.

  NOx is removed by carrying a NOx reduction catalyst on a filter disposed in the exhaust gas flow path. For example, there is selective catalytic reduction (SCR) in which NOx is reduced to nitrogen by injecting a zeolite-based catalyst into a filter and injecting a reducing agent obtained from an ammonia precursor such as urea or ammonia itself into the filter. .

  In order to remove PM and NOx, if PM adheres to the NOx reduction catalyst, the NOx reduction efficiency decreases. Therefore, it is necessary to arrange a device for removing NOx downstream of the device for removing PM. However, due to the demand for downsizing in the market, an apparatus in which an apparatus for removing PM and an apparatus for removing NOx are integrated is desired.

  Therefore, Patent Document 2 proposes that a wall flow type filter wall surface is covered with a NOx reduction catalyst layer made of NOx reduction catalyst and further covered with an oxidation catalyst layer made of an oxidation catalyst.

  On the other hand, an exhaust gas purification filter obtained by mixing and sintering aluminum titanate, which is a raw material particle of a carrier, and catalyst particles for burning PM into a filter shape and sintering the pressure loss due to PM deposition It is known that the rise is suppressed and the PM removal efficiency is increased. For example, Patent Document 3 proposes an exhaust gas filter in which aluminum titanate particles having a catalyst raw material attached to the surface are molded and sintered.

International Publication No. 2013/136991 JP 2000-282852 A International Publication 2012/046577

  However, in Patent Document 2, the pores on the filter wall surface are blocked by the formed catalyst layer, so that the connected pores independently reduce the exhaust gas flow path, resulting in a pressure loss due to PM deposition. There is a problem that the removal efficiency of PM and NOx decreases. The zeolitic catalyst which is a NOx reduction catalyst has low heat resistance, and there is a problem that when the same method as in Patent Document 3 is applied, the zeolitic catalyst is thermally deteriorated.

  An object of the present invention is to obtain an exhaust gas purification filter having a high NOx reduction efficiency by supporting a catalyst by a simple method without impregnating or applying a solution containing catalyst particles to a solution containing catalyst particles after production of the exhaust gas purification filter. The present invention provides an exhaust gas purification filter manufacturing method, an exhaust gas purification filter obtained by the exhaust gas purification filter manufacturing method, and an exhaust gas purification device including the filter.

  The present invention provides the following exhaust gas purification filter manufacturing method, exhaust gas purification filter, and exhaust gas purification device.

  Item 1 A step of producing a molded body by extruding a mixture containing zeolite and raw material particles of a carrier, a step of firing the molded body to produce a sintered body, and a pH of 4.0 or less. A method for producing an exhaust gas purification filter, comprising: a step of acid treatment under the above conditions; and a step of exchanging an element of an ion exchange site of zeolite contained in a sintered body after the acid treatment with a transition metal.

  Item 2. The method for producing an exhaust gas purification filter according to Item 1, comprising the zeolite as a catalyst for reducing nitrogen oxides to nitrogen.

  Item 3 The zeolite is one or more selected from mordenite type zeolite, faujasite type zeolite, A type zeolite, L type zeolite, β zeolite, and ZSM-5 type zeolite, Item 4. The method for producing an exhaust gas purification filter according to Item 2 or 3.

  Item 4 The method for producing an exhaust gas purification filter according to any one of Items 1 to 3, wherein the raw material particles of the carrier are aluminum titanate.

  Item 5. The method for producing an exhaust gas purification filter according to any one of Items 1 to 4, wherein the molded body is a honeycomb filter molded body.

  Item 6 An exhaust gas purification filter manufactured by the method for manufacturing an exhaust gas purification filter according to any one of Items 1 to 5.

  Item 7 An exhaust gas purification apparatus comprising the exhaust gas purification filter according to Item 6.

  According to the present invention, a catalyst can be supported by a simple method without impregnation or application of a solution containing catalyst particles into a solution containing catalyst particles after production of an exhaust gas purification filter, and NOx can be reduced and removed with high efficiency. .

  Hereinafter, an example of the preferable form which implemented this invention is demonstrated. However, the following embodiment is merely an example. The present invention is not limited to the following embodiments.

  The method for producing an exhaust gas purification filter of the present invention includes a step of extruding a mixture containing zeolite and raw material particles of a carrier to produce a molded body, a step of firing the molded body to produce a sintered body, A step of acid-treating the sintered body under a condition of pH 4.0 or less, and a step of exchanging an element at an ion exchange site of zeolite contained in the sintered body after the acid treatment with a transition metal. To do.

  The shape of the carrier of the exhaust gas purification filter is not particularly limited as long as it has a filtration function, and a conventionally known carrier can be used, for example, a honeycomb filter. Specifically, a ceramic wall flow type honeycomb filter is preferably used.

  As the ceramic raw material particles, silicon carbide, cordierite, mullite, alumina, aluminum titanate and the like are preferably used, and aluminum titanate is more preferable from the viewpoint of heat resistance and stability. A sintering aid such as talc, silicon oxide, mullite, alkali oxide, alkaline earth oxide, etc. may be added to the ceramic raw material particles as appropriate.

  If it is a wall flow type, the number of cells and the wall thickness are not particularly limited, but the number of cells is preferably 200 to 400 cells / in 2 and the wall thickness is preferably 200 to 380 μm. The cell wall surface is not particularly limited as long as it is porous, but preferably has pores having a major axis of about 8 to 18 μm and a porosity of 45 to 65%.

  Zeolite is a crystalline aluminosilicate, which is a porous body having a crystal structure in which four oxygen elements are regularly and three-dimensionally bonded around silicon and aluminum elements. Examples of the crystal structure of the zeolite used in the present invention include mordenite type zeolite, faujasite type zeolite, A type zeolite, L type zeolite, β zeolite, and ZSM-5 type zeolite.

  The silica / alumina ratio of the zeolite used in the present invention is preferably 15 or more, and more preferably 20 or more. The upper limit of the silica / alumina ratio is preferably 100, and more preferably 50. With this configuration, it is considered that NOx can be reduced and removed without being affected by alkali metal ions eluted from other additives.

  The zeolite used in the present invention includes naturally-occurring and synthetic zeolites, and any zeolite having the above-described configuration can be used without any particular limitation. Preferably, synthetic zeolite is preferred because it has a more uniform silica / alumina ratio, crystal size, crystal morphology, and fewer impurities.

  The mixture containing the zeolite and the raw material particles of the carrier can be prepared by adding, for example, a pore-forming agent, a binder, a dispersant, and water. The zeolite is preferably blended in an amount of 1 to 40 parts by mass, more preferably 1 to 30 parts by mass with respect to 100 parts by mass of the carrier raw material particles.

  If necessary, the above mixture may contain a catalyst for burning PM, thereby making it possible to achieve both the function of removing PM and the function of removing NOx, and further increase the pressure loss. An exhaust gas purification filter that can be solved can be obtained.

  As the catalyst for burning PM that can be used, any catalyst that does not thermally deteriorate at the firing temperature of the raw material particles of the carrier can be used without particular limitation. For example, one or more selected from alkali metals can be used. An oxide containing an element and one or more elements selected from Zr, Si, Al, and Ti can be given. The oxide is also preferable because it is thought to suppress elution of alkali metal and prevent the decomposition of zeolite.

More _{specifically, A 2X Zr X Si Y O} 3X + 2Y, A X Al X Si Y O 2X + 2Y, A 2X Ti X Si Y O 3X + 2Y, A 2X Ti Y O X + 2Y, A 2X Zr Y O X + 2Y, A X Al it can be represented by the general formula such as _{Y O X / 2 + 3Y /} 2. In the formula, A represents an alkali metal, X represents a positive real number satisfying 1 ≦ X ≦ 2, and Y represents a positive real number satisfying 1 ≦ Y ≦ 6. More preferably, Y is a positive real number that satisfies 1 ≦ Y ≦ 4. Examples of the alkali metal include Li, Na, K, Rb, Cs, and Fr. Among these, Li, Na, K, and Cs are preferable from the economically advantageous point.

The _{A 2X Zr X Si Y O 3X} + 2Y, for _{example, Li 2 ZrSiO 5, Na 2} ZrSiO 5, Na 4 Zr 2 Si 3 O 12, Na 2 ZrSi 2 O 7, Na 2 ZrSi 3 O 9, K 2 ZrSiO 5 K ₂ ZrSi ₂ O ₇ , K ₂ ZrSi ₃ O ₉ , Cs ₄ Zr ₂ Si ₃ O ₁₂ , Cs ₂ ZrSi ₂ O ₇ , Cs ₂ ZrSi ₃ O _{9 and the} like can be exemplified.

As A _X Al _X Si _Y O _{2X + 2Y} , for example, LiAlSiO ₄ , LiAlSi ₂ O ₆ , LiAlSi ₃ O ₈ , NaAlSiO ₄ , NaAlSi ₂ O ₆ , NaAlSi ₃ O ₈ , KAlSiO ₄ , KAlSi ₂ O ₆ , KAlSi ₃ O ₈ etc. can be illustrated.

A _2X Ti _X Si _Y O The _{3X + 2Y,} for _{example, Li 2 TiSiO 5, Li 2} TiSi 2 O 7, Li 2 TiSi 3 O 9, Na 2 TiSiO 5, Na 2 TiSi 2 O 7, Na 2 TiSi 3 O 9 , K ₂ TiSiO ₅ , K ₂ TiSi ₂ O ₇ , K ₂ TiSi ₃ O _{9 and the} like.

Examples of A _2X Ti _Y O _{X + 2Y} include Na ₂ TiO ₃ , Na ₂ Ti ₂ O ₅ , Na ₂ Ti ₄ O ₉ , Na ₂ Ti ₆ O ₁₃ , Na ₂ Ti ₈ O ₁₇ , K ₂ TiO ₃ , K _{2 Ti 2 O 5, K 2} Ti 4 O 9, K 2 Ti 6 O 13, K 2 Ti 8 O 17 and the like can be exemplified.

The _{A 2X Zr Y O X + 2Y} , for _example, can be exemplified _{Na 2 ZrO 3, K 2 ZrO} 3 and the like.

Examples of A _X Al _Y O _{X / 2 + 3Y / 2} include NaAlO ₂ , NaAl ₅ O ₈ , KAlO ₂ , KAl ₅ O _{8, and the} like.

Preferably, the oxide used in the present _invention are _{A 2X Zr X Si Y O 3X} + 2Y, A X Al X Si Y O 2X + 2Y, A 2X Ti X Si Y O 3X + 2Y, A 2X Ti Y O X + 2Y.

  By firing the above mixture, for example, using an extrusion molding machine to form a honeycomb structure, and firing the molded body obtained after plugging one side so that the cell openings have a checkered pattern A sintered body can be prepared. Firing conditions are appropriately selected depending on the raw material particles of the carrier to be used. When aluminum titanate is used as the raw material particles of the carrier, the firing temperature is 900 to 1100 ° C., and the firing time is 2 to 15 hours. Can be mentioned.

  The acid treatment can be performed by treating the sintered body with an acidic solution having a pH of 4.0 or less in which an acid and a solvent are mixed. As the acid, for example, inorganic acids such as sulfuric acid, acetic acid and nitric acid, and organic acids such as formic acid and acetic acid may be used, and two or more kinds may be used in combination as required.

  As the solvent, water; alcohols such as methanol, ethanol, propanol, butanol; mixed solvents thereof and the like can be used, and water is preferable because of its versatility. As the treatment method, impregnation, spraying, a flow method or the like can be used, and impregnation is preferable. As processing temperature, it is preferable to carry out at 25-100 degreeC. The amount of the acid mixed may be set so that the pH of the acidic aqueous solution is 4.0 or less, preferably 3.0 or less, more preferably 0.1 or more and 3.0 or less.

  Zeolite is considered to easily undergo de-Alization at the calcination temperature of the carrier raw material particles and easily deteriorate due to heat. However, the zeolite skeleton is treated by treatment with an acidic solution having a pH of 4.0 or less after calcination. It is estimated that Al can be inserted again.

  After the acid treatment, the exhaust gas purifying filter of the present invention can be manufactured by exchanging the element of the ion exchange site of the zeolite contained in the sintered body with a transition metal. If the element of an ion exchange site can be exchanged for a transition metal, the exchange method is not particularly limited, and for example, a method such as an ion exchange method can be employed. In addition, the exchange amount for the transition metal can be appropriately selected depending on the desired catalytic activity, and a part or all of the exchange amount can be used for the transition metal.

Examples of the element of the ion exchange site of zeolite include H, NH ₄ , K, and Na.

  Examples of the transition metal include Cu, Fe, Pt, Ag, Ti, Mn, Ni, Co, Pd, Rh, V, and Cr, and Fe and Cu are preferable. Examples of the raw material used for the exchange to the transition metal include transition metal nitrates and acetates. The total amount of transition metals is preferably 1 to 15% by mass, more preferably 1 to 8% by mass, based on the total weight of the zeolite.

  In the present invention, the exhaust gas to be treated includes exhaust gas discharged from an internal combustion engine such as a diesel engine or a gasoline engine, and exhaust gas from various combustion facilities.

  The exhaust gas purification filter according to the present invention can be manufactured according to the method for manufacturing an exhaust gas purification filter of the present invention. The exhaust gas purification filter of the present invention is used in contact with exhaust gas by being disposed in the exhaust gas passage. Removal of NOx in the exhaust gas is performed in the presence of a reducing agent, for example, an ammonia precursor such as urea, ammonium carbonate, hydrazine, ammonium hydrogen carbonate, or ammonia itself. The reducing agent may be disposed upstream of the exhaust gas purification filter of the present invention in the exhaust gas flow path, and a necessary amount may be appropriately supplied.

  The exhaust gas purification filter of the present invention has high NOx reduction efficiency and can be manufactured by a simple method. During production, the raw material mixture can also contain a catalyst for burning PM, so that the exhaust gas purification filter of the present invention can burn PM, which is a harmful substance in exhaust gas, at a low temperature and reduce NOx by a single filter. You can also Due to its excellent function, it can be suitably used for a diesel engine filter (DPF), a gasoline engine filter and the like, and can meet the demand for downsizing in the market.

(Exhaust gas purification device)
The exhaust gas purification apparatus of the present invention includes the exhaust gas purification filter of the present invention. In addition to the exhaust gas purification filter of the present invention, for example, a means for supplying a reducing agent or the like to the exhaust gas purification filter is further provided. Or when the catalyst which burns PM is contained in the exhaust gas purification filter of this invention, the means etc. which heat an exhaust gas purification filter in order to decompose | disassemble accumulated PM are further provided.

  Hereinafter, the present invention will be described in more detail based on examples. The present invention is not limited to the following examples, and can be implemented with appropriate modifications without departing from the scope of the invention.

[Zeolite]
(Synthesis Example 1)
A slurry was prepared by mixing 1000 ml of a 10% by mass aqueous copper acetate solution and 400 g of ZSM-5 type zeolite (HSZ-840NHA, manufactured by Tosoh Corporation) and stirring at 60 ° C. for 12 hours. The solid content of the prepared slurry was filtered off, washed with 1000 ml of ion exchange water, and dried at 110 ° C. for 6 hours.

  The obtained particulate solid was measured by fluorescent X-ray, and it was confirmed that the ion exchange site of the zeolite was ion exchanged with copper. The obtained zeolite was used in Comparative Example 4.

[Oxide]
(Synthesis Example 2)
Sodium carbonate 32.3 parts by mass, aluminum oxide 31.1 parts by mass, and silicon oxide 36.6 parts by mass were mixed and baked at 1200 ° C. for 4 hours. The obtained particulate solid was confirmed to be a single phase of NaAlSiO ₄ by X-ray diffraction.

[Manufacture of exhaust gas purification filters]
Example 1
For 20 parts by mass of ZSM-5 type zeolite (HSZ-840NHA: manufactured by Tosoh Corporation), 80 parts by mass of aluminum titanate (manufactured by Marusu Yakuyaku Co., Ltd.), 10 parts by weight of NaAlSiO ₄ produced in Synthesis Example 2, and graphite 3 Part by mass, 10 parts by mass of methylcellulose, and 0.5 parts by mass of fatty acid soap were blended, and an appropriate amount of water was added and kneaded to obtain an extrudable clay.

The obtained kneaded material was extruded and molded to form a honeycomb structure with an extrusion molding machine, and a molded body was obtained. The cell density of the mold was 300 cells / square inch (46.5 cells / cm ² ), and the partition wall thickness was 300 μm.

  A slurry having a solid content substantially composed of the above-described granular aluminum titanate particles and zeolite, and an additive such as a viscosity modifier was added. In addition, the ratio of the solid content in a slurry is the same as the above. In the molded body which is a honeycomb structure, this slurry was injected into the cells of the honeycomb structure and sealed so that the opened cells and the sealed cells were alternately in a checkered pattern.

  The obtained molded body was held at 600 ° C. for 10 hours, then heated to 1000 ° C. at 25 ° C./hour and then fired by holding at 1000 ° C. for 10 hours. A honeycomb structure was obtained.

  The obtained honeycomb structure was impregnated with a sulfuric acid aqueous solution adjusted to pH 1.0, maintained at 80 ° C. for 5 hours, sufficiently washed with running water, and dried at 60 ° C.

  Next, it was impregnated with a 10% by mass aqueous copper acetate solution and kept at 60 ° C. for 12 hours. Thereafter, the exhaust gas purification filter was manufactured by thoroughly washing with ion exchange water and heating at 600 ° C. for 2 hours.

(Example 2)
An exhaust gas purification filter was produced in the same manner as in Example 1 except that the sulfuric acid aqueous solution adjusted to pH 1.0 was changed to a sulfuric acid aqueous solution adjusted to pH 2.0.

Example 3
An exhaust gas purification filter was produced in the same manner as in Example 1 except that the sulfuric acid aqueous solution adjusted to pH 1.0 was changed to a sulfuric acid aqueous solution adjusted to pH 3.0.

Example 4
The same procedure as in Example 1 was performed except that the sulfuric acid aqueous solution adjusted to pH 1.0 was changed to an acetic acid aqueous solution adjusted to pH 2.0.

(Example 5)
An exhaust gas purification filter was produced in the same manner as in Example 1, except that the sulfuric acid aqueous solution adjusted to pH 1.0 was changed to a hydrochloric acid aqueous solution adjusted to pH 1.0.

(Comparative Example 1)
An exhaust gas purification filter was produced in the same manner as in Example 1, except that the sulfuric acid aqueous solution adjusted to pH 1.0 was changed to a hydrochloric acid aqueous solution adjusted to pH 5.0.

(Comparative Example 2)
An exhaust gas purification filter was produced in the same manner as in Example 1 except that the sulfuric acid aqueous solution adjusted to pH 1.0 was changed to a sulfuric acid aqueous solution adjusted to pH 6.0.

(Comparative Example 3)
For 20 parts by mass of ZSM-5 type zeolite (HSZ-840NHA: manufactured by Tosoh Corporation), 80 parts by mass of aluminum titanate (manufactured by Marusu Yakuyaku Co., Ltd.), 10 parts by weight of NaAlSiO ₄ produced in Synthesis Example 2, and graphite 3 Part by mass, 10 parts by mass of methylcellulose, and 0.5 parts by mass of fatty acid soap were blended, and an appropriate amount of water was added and kneaded to obtain an extrudable clay.

The obtained kneaded material was extruded and molded to form a honeycomb structure with an extrusion molding machine, and a molded body was obtained. The cell density of the mold was 300 cells / square inch (46.5 cells / cm ² ), and the partition wall thickness was 300 μm.

  A slurry having a solid content substantially composed of the above-described granular aluminum titanate particles and zeolite and added with additives such as a viscosity modifier was prepared. In addition, the ratio of the solid content in a slurry is the same as the above. In the molded body which is a honeycomb structure, this slurry was injected into the cells of the honeycomb structure and sealed so that the opened cells and the sealed cells were alternately in a checkered pattern.

  The obtained molded body was held at 600 ° C. for 10 hours, then heated to 1000 ° C. at 25 ° C./hour and then fired by holding at 1000 ° C. for 10 hours. A honeycomb structure was obtained.

  The obtained honeycomb structure was impregnated with a 10% by mass aqueous copper acetate solution and held at 60 ° C. for 12 hours. Thereafter, the exhaust gas purification filter was manufactured by thoroughly washing with ion exchange water and heating at 600 ° C. for 2 hours.

(Comparative Example 4)
90 parts by weight of aluminum titanate (manufactured by Marusu Shakuyaku Co., Ltd.), 10 parts by weight of graphite, 10 parts by weight of methylcellulose, and 0.5 parts by weight of fatty acid soap are added, and an appropriate amount of water is added and kneaded. I got a good dredge.

The obtained kneaded material was extruded and molded to form a honeycomb structure with an extrusion molding machine, and a molded body was obtained. The cell density of the mold was 300 cells / square inch (46.5 cells / cm ² ), and the partition wall thickness was 300 μm.

  A slurry having a solid content substantially composed of the above-described granular aluminum titanate particles and added with additives such as a viscosity adjusting material was prepared. In addition, the ratio of the solid content in a slurry is the same as the above. In the molded body which is a honeycomb structure, this slurry was injected into the cells of the honeycomb structure and sealed so that the opened cells and the sealed cells were alternately in a checkered pattern.

  The obtained molded body was held at 600 ° C. for 10 hours, then heated to 1450 ° C. at 25 ° C./hour and then fired by holding at 1450 ° C. for 10 hours, so that the pore diameter was 12 μm and the porosity was 51%. A honeycomb structure was obtained.

  Next, 40 parts by mass of zeolite produced in Synthesis Example 1 was mixed with 20 parts by mass of silica sol and 40 parts by mass of water to prepare a slurry. The honeycomb structure was immersed in the prepared slurry. After immersion, it was baked at 600 ° C. to 700 ° C. for about 4 hours to produce an exhaust gas purification filter.

  The amount of zeolite supported on the honeycomb structure was 19 parts by mass with respect to 90 parts by mass of aluminum titanate.

[Evaluation of exhaust gas purification equipment]
(NOx concentration evaluation)
An exhaust gas purification filter is impregnated in advance with an aqueous urea solution and dried at 50 ° C., and the exhaust gas purification filter is installed in a simulated exhaust gas exhaust line. Thereafter, simulated exhaust gas (O ₂ : 10%, N ₂ : 90%, NO: 200 ppm, NO ₂ : 200 ppm) was raised to 300 ° C., and the NOx concentration was measured. The results are shown in Table 1.

(PM deposition pressure loss evaluation)
An initial weight of the exhaust gas purification filter is measured in advance, and an oxidation catalyst (DOC) and an exhaust gas purification filter are sequentially installed in the exhaust line of the diesel engine. Next, after starting the diesel engine and depositing a predetermined amount (about 4 g / L) of PM at a low temperature, the exhaust gas purification filter was removed and the weight of the deposited PM was confirmed, and then the pressure loss was measured.

(Filter regeneration rate)
An initial weight of the exhaust gas purification filter is measured in advance, and an oxidation catalyst (DOC) and an exhaust gas purification filter are sequentially installed in the exhaust line of the diesel engine. Next, after starting the diesel engine and depositing a predetermined amount (about 8 g / L) of PM at a low temperature, the exhaust gas purification filter is once removed and the weight of the deposited PM is measured.

Next, after the exhaust gas purification filter was installed in the simulated exhaust gas exhaust line, the simulated exhaust gas was raised to 540 ° C. and a regeneration test was started. The temperature of 540 ° C. ± 10 ° C. was maintained for 30 minutes from the time of reaching 540 ° C., and after 30 minutes, the simulated exhaust gas was switched to the total amount N ₂ .

  After the temperature dropped to room temperature, the exhaust gas purification filter was taken out again and the weight loss (= PM combustion weight) was measured.

  The regeneration rate was calculated by the following formula. The results are shown in Table 2.

  Regeneration rate (%) = 100 − [(PM deposition weight (g) −PM combustion weight (g)) / PM deposition weight (g)] × 100

  As is apparent from the results shown in Table 1, when the exhaust gas purification filters of Examples 1 to 5 according to the present invention are used, the NOx concentration is reduced and the pressure loss is also kept low. On the other hand, when the exhaust gas purification filters of Comparative Examples 1 to 3 that are not acid-treated under a pH of 4 or less are used, the NOx concentration is high. In Comparative Example 4 in which zeolite is supported by the dipping method, the NOx concentration is low, but the pressure loss is large.

Item 3 The zeolite is one or more selected from mordenite type zeolite, faujasite type zeolite, A type zeolite, L type zeolite, β zeolite, and ZSM-5 type zeolite, Item 3. A method for producing an exhaust gas purification filter according to Item 1 or 2 .

Claims (7)

A step of producing a molded body by extruding a mixture containing zeolite and carrier raw material particles;
Firing the molded body to produce a sintered body;
A step of acid-treating the sintered body under a condition of pH 4.0 or less;
And a step of exchanging the element of the ion exchange site of the zeolite contained in the sintered body after the acid treatment with a transition metal.   The method for producing an exhaust gas purification filter according to claim 1, wherein the zeolite is contained as a catalyst for reducing nitrogen oxides to nitrogen.   The zeolite is one or more selected from mordenite type zeolite, faujasite type zeolite, A type zeolite, L type zeolite, β zeolite, and ZSM-5 type zeolite. A method for producing an exhaust gas purification filter according to 2 or 3.   The method for producing an exhaust gas purification filter according to any one of claims 1 to 3, wherein the carrier material particles are aluminum titanate.   The method for manufacturing an exhaust gas purification filter according to any one of claims 1 to 4, wherein the molded body is a molded body of a honeycomb filter.   An exhaust gas purification filter manufactured by the method for manufacturing an exhaust gas purification filter according to any one of claims 1 to 5.   An exhaust gas purification apparatus comprising the exhaust gas purification filter according to claim 6.