JPH0899033A - Hydrocarbon adsorbent - Google Patents

Abstract

PURPOSE: To increase the desorption temperature of hydrocarbons and to improve heat resistance by including silver, group IIIB elements in the periodic table, and crystalline aluminosilicate and ion-exchanging the group IIIB elements by the crystalline aluminum silicate in an adsorbent for hydrocarbon which is used in an exhaust purifier. CONSTITUTION: An adsorbent containing silver, group IIIB elements in the periodic table, and crystalline aluminoslicate is used to adsorb an unburned hydrocarbon in exhaust gas discharged from internal combustion engines such as automobiles. The acid strength of the crystalline aluminum silicate is increased by adding a rare earth element or using colloidal ceria or lanthanum hydroxide sol in the preparation of aluminosilicate to improve the stability of silver after endurance. At least one kind of compound selected from the group consisting of MFI, BEA, FAUD, MOR, FER, ERI, LTL and CHA-type zeolite is used as the crystalline aluminosilicate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrocarbon adsorbent, and more particularly to a hydrocarbon adsorbent used in an exhaust gas purification apparatus for exhaust gas discharged from an internal combustion engine of an automobile or the like.

[0002]

2. Description of the Related Art Conventionally, in order to purify exhaust gas from an internal combustion engine such as an automobile, a three-way catalyst is usually used at the exhaust outlet. The exhaust gas temperature at which this catalyst exerts its purifying ability generally needs to be 300 ° C. or higher.

However, even if the conventional three-way catalyst is arranged immediately after the exhaust manifold, a large amount of unburned hydrocarbons are discharged from the internal combustion engine at the time of engine start, and since the exhaust gas temperature is low, the catalytic activity is low. Is discharged without being purified. On the other hand, since the exhaust gas discharged from the engine during normal operation becomes high in temperature, the exhaust gas purifying catalyst is required to have heat resistance.

As an exhaust gas purifying apparatus for solving the above-mentioned problems, a hydrocarbon having a high adsorbing ability for hydrocarbons in the exhaust gas in a low temperature range at the time of engine starting, and a hydrocarbon coated on an adsorbent, or contained in the exhaust gas. There has been proposed an adsorbent capable of sustaining an adsorbing ability to effectively remove and remove soot (Japanese Patent Laid-Open No. 5-317701).

Further, regarding the crystalline aluminosilicate which is a base material used for adsorbing hydrocarbons in exhaust gas, a rare earth metal produced by allowing a rare earth metal salt to be present in a raw material for producing a crystal at the time of producing a crystal. By using an exhaust gas purifying catalyst containing a crystalline aluminosilicate containing at least one metal atom selected from metals belonging to Group 1b and Group VIII of the periodic table, contact with high temperature exhaust gas is achieved. It is disclosed in Japanese Patent Laid-Open No. 5-031372 that exhaust gas purification performance is not deteriorated even if it is carried out.

Further, as a hydrocarbon adsorbent having a high hydrothermal stability, which adsorbs and removes hydrocarbons discharged from exhaust gas at low temperatures at which the three-way catalyst is not activated, crystalline alumino having an MFI structure containing phosphorus. A hydrocarbon adsorbent using a silicate has been proposed (JP-A-6-063394).

[0007]

However, in the adsorbent disclosed in the above-mentioned JP-A-5-317701, colloidal ceria and water are used as a method of incorporating a rare earth oxide or a precursor thereof for improving the oxidation activity. Although lanthanum oxide sol is used, such a method cannot improve the dispersity of the supported metal, and thus has a drawback in that sintering of the metal after endurance cannot be suppressed.

Further, in the exhaust gas purifying catalyst disclosed in JP-A-5-031372, a rare earth metal is contained in the crystalline aluminosilicate in order to improve the heat resistance of the exhaust gas purifying catalyst. Although a crystalline aluminosilicate containing a rare earth metal is used, the crystalline aluminosilicate has a high degree of crystallinity after heat treatment, but when used as a hydrocarbon adsorbent, the heat resistance of the metal cannot be retained. was there.

When the conventional exhaust gas purifying adsorbent or catalyst as described above is used as an exhaust gas purifying adsorbent for an internal combustion engine of an automobile or the like, the hydrocarbons in the low temperature range at the time of engine start in the initial performance. It is possible to adsorb and to retain the adsorbed hydrocarbon up to a temperature at which the catalytic metal is activated, so that it effectively functions.

However, in the performance after endurance due to contact with exhaust gas in a high temperature range, the carried metal will be sintered and adsorb hydrocarbons in a low temperature range, but will be adsorbed up to a temperature at which the catalytic metal is activated. There is a drawback that the hydrocarbons cannot be retained and are discharged without being purified.

On the other hand, in the hydrocarbon adsorbent disclosed in the above-mentioned JP-A-6-06394, the phosphorus-supported MFI is used.
-Type zeolite is used as an adsorbent, and ZSM-5 has high hydrothermal stability, but since it does not carry a metal, the amount of adsorbed hydrocarbons is not sufficient, and its desorption also activates the three-way catalyst. It starts before it turns into.

Accordingly, the object of the present invention is to have a large adsorption capacity for hydrocarbons, a high desorption temperature of the adsorbed hydrocarbons, and a heat resistance to the extent that it can be used as a catalyst for automobiles. It is to provide a hydrocarbon adsorbent for purifying hydrocarbons in exhaust gas.

[0013]

As a result of intensive studies to solve the above problems, the present inventors have found that as an adsorbent for adsorbing unburned hydrocarbons in exhaust gas discharged from an internal combustion engine of an automobile or the like, it is crystalline. When the group IIIB and silver are supported on the aluminosilicate and the ion exchange method is used as a method for supporting the group IIIB, the exhaust gas purifying ability is prevented from lowering due to contact with the exhaust gas at high temperature, and at the same time, high temperature gas is used. The inventors have found that the ability to adsorb and desorb hydrocarbons after contact, and also the heat resistance of metals can be maintained, and have reached the present invention.

The above object of the present invention is characterized in that it contains silver, Group IIIB of the Periodic Table and a crystalline aluminosilicate, and the Group IIIB is ion-exchanged with the crystalline aluminosilicate. Achieved with a hydrocarbon adsorbent.

In the present invention, by supporting silver and Group IIIB on the crystalline aluminosilicate forming a crystal structure, the adsorption amount of unburned hydrocarbons discharged at the time of engine start is improved and the catalyst is activated. Desorption can be suppressed up to the temperature at which it becomes stable.

Further, since the Group IIIB is ion-exchanged with the crystalline aluminosilicate, a crystal is obtained by adding a rare earth element during the synthesis of the crystalline aluminosilicate or by using colloidal ceria or lanthanum hydroxide sol. The acid strength of the aluminosilicate is increased, and the stability of silver after endurance can be increased.

As the crystalline aluminosilicate, MF
I (pore size: 5.1-5.6Å), BEA (pore size: 5.6-)
7.6 Å), FAU (pore size: 7.4 Å), MOR (pore size: 2.6 to 7.0 Å), FER (pore size: 3.5 to 5.4)
Å), ERI (pore size: 3.6 to 5.2 Å), LTL (pore size: 7.1 Å) and CHA type zeolite (pore size: 3.8)
At least one selected from the group consisting of Å) can be used. The pore size of these crystalline aluminosilicates is particularly excellent in hydrocarbon adsorption. Among the crystalline aluminosilicates, the crystal structure is particularly excellent in heat resistance.

The preferred Si / 2Al of the above zeolites depends on the zeolite species. For example, the MFI type is 10
1000, BEA type 20 to 50, MOR type 10 to 5
0, FER type is 7 to 20, ERI type is 5 to 7, LTL type is 5 to 7, CHA type is 3 to 5, and FAU type is preferably 5 to 30. If it is smaller than these values, the synthesis becomes difficult, and conversely, if it is larger than these values, the amount of metal supported is decreased and the effect is rather reduced. Further, by using several kinds of zeolite species having different pore sizes, various kinds of hydrocarbons contained in the exhaust gas composition can be adsorbed.

The group IIIA of the periodic table can be appropriately selected from at least one selected from the group consisting of cerium, lanthanum, neodymium, praseodymium, promethium, samarium, europium and yttrium, and particularly cerium. At least one selected from the group consisting of, lanthanum, neodymium and yttrium is preferable. In the present invention, ion exchange of at least one selected from the group consisting of cerium, lanthanum, neodymium and yttrium as the group IIIA is particularly effective in stabilizing silver after endurance.

As the rare earth metal source, an inorganic salt or organic salt of the metal, for example, chloride, bromide, carbonate, nitrate, nitrite, acetate, formate, tartrate, etc., may be appropriately selected and used. However, it is particularly preferable to use nitrates, acetates and chlorides.

The group IIIB ion exchange is preferably carried out before the silver is loaded or at the same time as the silver is loaded. By loading Group IIIB before silver, which is the catalyst metal, the total acid content of the crystalline aluminosilicate increases, so that the acid sites enhance the interaction with silver and increase the stability of silver after endurance. To do. On the other hand, by supporting the Group IIIB at the same time, the silver is highly dispersed and supported, and the sintering of the silver after endurance is suppressed. However, if the Group IIIB is supported after the silver is supported, the silver cannot be stabilized.

As a method for supporting silver, any known method can be appropriately selected and used, and examples thereof include an ion exchange method, an impregnation supporting method, and a dipping method. In particular, the ion exchange method is used. Is preferred. As the silver starting salt, a soluble salt can be used,
Particularly preferred are nitrates, acetates and oxalates.

The content of silver in the crystalline aluminosilicate is preferably in the range of 0.1 to 15% by weight in terms of silver amount. If the amount of silver is less than 0.1% by weight, the effect of adsorbing hydrocarbons cannot be obtained, and if it exceeds 15% by weight,
Pore blockage occurs and the amount of adsorption decreases.

In the present invention, silver can be further stabilized by supporting phosphorus. The supported amount of phosphorus is preferably in the range of 0.01 to 5% by weight.
When silver is added within this range, the amount of silver supported increases and the stability of silver after endurance increases. As a method for supporting phosphorus, a known method can be appropriately selected and used. Also, phosphorus is before loading silver,
It is preferable that silver is loaded at the same time. Starting salts of phosphorus include elemental phosphorus and phosphorus compounds.
Among these, in particular, an alkali metal salt such as a lithium salt or a sodium salt or a phosphate such as an ammonium salt is used to obtain a catalyst having excellent heat resistance.

[0025]

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto. Further, unless otherwise specified, the parts and% described below represent parts by weight and% by weight, respectively.

Example 1 337.5 g of aluminum sulfate (18-hydrate), sulfuric acid (9
7%) 362.5 g and water 7841 cc (A
Liquid), water glass (JIS-3 sodium silicate) 5
Solution consisting of 275.0 g and 5000 cc of water (referred to as solution B) and sodium chloride 987.5 g, water 2300 cc
The following solutions (referred to as liquid C) were prepared. Next, while stirring the liquid C at room temperature, the liquid A and the liquid B
The liquid was gradually added dropwise.

Next, mordenite [TSZ-610NAA (trade name), Toso-Co., Ltd.] was seeded in this mixed solution as seed crystals.
12.5g of powder of
(Capacity: 300 liters) with stirring.
pm) and reacted for 20 hours under self-pressure. Next, after cooling the reaction mixture, the solid substance was separated by filtration. Subsequently, 280 liters of water was added to the solid matter, and washing with water and filtration were repeated. Then, the obtained solid matter was dried at 120 ° C. for one day and then calcined in air at 550 ° C. for 4 hours to obtain 1200 g of a crystalline aluminosilicate. This crystalline aluminosilicate showed MFI as a result of X-ray diffraction.
It was structurally similar to known zeolite ZSM-5 having a structure.

Next, this crystalline aluminosilicate was added to a solution of 1435 g of ammonium nitrate and 10800 g of water, and the ammonium exchange was carried out by stirring and filtering at room temperature for 3 hours. This operation was repeated three times to increase the ion exchange rate. The obtained NH ₄ type crystalline aluminosilicate was dried at 120 ° C. for one day and then calcined in air at 550 ° C. for 4 hours to obtain an H type crystalline aluminosilicate. As a result of X-ray diffraction, this aluminosilicate had an MFI structure.

H type MFI type zeolite (Si / 2Al =
The powder of 30) was stirred in an aqueous cerium nitrate solution having a concentration of 0.3 M for 12 hours and then filtered, and the zeolite was loaded with cerium by ion exchange. The obtained powder is dried and then calcined, and then silver nitrate (Ag
After stirring for 12 hours in an aqueous solution of NO ₃ ), the zeolite was loaded with silver by filtering.

The zeolite was dried and then calcined to obtain an adsorbent 1. 100 parts by weight of this adsorbent, 65 parts of silicogel (solid content 20%) and 65 parts of water were put into a magnetic pot, and mixed with a vibration mill device for 40 minutes or a universal ball mill device for 6.5 hours and pulverized for washcoating. A slurry was produced.

The cordierite monolith carrier was suction-coated to remove excess slurry. Then, it dried and pre-baked at 400 degreeC for about 1 hour. This coated the zeolite with a coating amount of about 90 g / L. The above wash-coating, drying and calcination were further repeated twice to coat a total of about 200 g / L of zeolite, and calcination was carried out at 400 ° C. for 1 hour in an air atmosphere. The amount of silver supported on this adsorbent was 7% by weight and that of cerium was 4% by weight.

Example 2 An adsorbent was prepared in the same manner as in Example 1 except that lanthanum nitrate was used instead of cerium nitrate. 7% by weight of silver and 3.9% of lanthanum were supported in this adsorbent.
% By weight.

Example 3 Except that neodymium nitrate was used instead of cerium nitrate,
An adsorbent was prepared in the same manner as in Example 1. The amount of silver supported on this adsorbent was 7% by weight and that of neodymium was 3.9% by weight.

Example 4 An adsorbent was prepared in the same manner as in Example 1 except that yttrium nitrate was used instead of cerium nitrate. The silver and the yttrium supported on this adsorbent were 7% by weight and 4% by weight, respectively.

Example 5 The same method as in Example 1 except that BEA type zeolite (Si / 2Al = 25 Philadelphia Corporation, trade name: CP811 BL-25) was used in place of the H type MFI type zeolite. To prepare an adsorbent. The silver and cerium supported on this adsorbent were 6.8% by weight and 3.8% by weight, respectively.

Example 6 Adsorption was carried out in the same manner as in Example 1 except that BEA type zeolite (Si / 2Al = 25) was used instead of H type MFI type zeolite and lanthanum nitrate was used instead of cerium nitrate. The agent was prepared. The amount of silver and lanthanum supported on this adsorbent was 7% by weight and 3.9% by weight, respectively.

Example 7 Adsorption was carried out in the same manner as in Example 1 except that BEA type zeolite (Si / 2Al = 25) was used instead of H type MFI type zeolite and neodymium nitrate was used instead of cerium nitrate. The agent was prepared. The amount of silver supported on this adsorbent was 7% by weight and that of neodymium was 3.9% by weight.

Example 8 Adsorption was carried out in the same manner as in Example 1 except that BEA type zeolite (Si / 2Al = 25) was used instead of H type MFI type zeolite and yttrium nitrate was used instead of cerium nitrate. The agent was prepared. The silver and the yttrium supported on this adsorbent were 7% by weight and 4% by weight, respectively.

Example 9 The same method as in Example 1 except that FAU type zeolite (Si / 2Al = 5.2 Philadelphia Corporation, trade name: CBV 500) was used in place of the H type MFI type zeolite. To prepare an adsorbent. Silver adsorbed on this adsorbent was 8.9% by weight, and cerium was 4.
It was 8% by weight.

Example 10 The same method as in Example 1 except that FAU type zeolite (Si / 2Al = 5.2) was used in place of the H type MFI type zeolite and lanthanum nitrate was used in place of the cerium nitrate. To prepare an adsorbent. Silver and lanthanum supported on this adsorbent were 9% by weight and 4.9% by weight, respectively.

Example 11 The same method as in Example 1 except that FAU type zeolite (Si / 2Al = 5.2) was used in place of the H type MFI type zeolite and neodymium nitrate was used in place of the cerium nitrate. To prepare an adsorbent. The silver supported on this adsorbent was 8.8% by weight, and the neodymium was 4.9% by weight.

Example 12 The same method as in Example 1 except that FAU type zeolite (Si / 2Al = 5.2) was used in place of the H type MFI type zeolite and yttrium nitrate was used in place of the cerium nitrate. To prepare an adsorbent. The silver and the yttrium supported on this adsorbent are 9.1% by weight and 5.1% by weight, respectively.
Met.

Example 13 Adsorption was carried out in the same manner as in Example 1 except that MOR type zeolite (Si / 2Al = 13 Philadelphia Corporation, trade name: CBV 10A) was used in place of the H type MFI type zeolite. The agent was prepared. Silver adsorbed on this adsorbent was 7.8% by weight, and cerium was 4.4.
% By weight.

Example 14 Adsorption was carried out in the same manner as in Example 1 except that MOR type zeolite (Si / 2Al = 13) was used instead of H type MFI type zeolite and lanthanum nitrate was used instead of cerium nitrate. The agent was prepared. The amount of silver and lanthanum supported on this adsorbent was 8.1% by weight and 4.6% by weight, respectively.

Example 15 Adsorption was carried out in the same manner as in Example 1 except that MOR type zeolite (Si / 2Al = 13) was used in place of the H type MFI type zeolite, and neodymium nitrate was used in place of the cerium nitrate. The agent was prepared. The silver supported on this adsorbent was 7.9% by weight and the neodymium was 4.4% by weight.

Example 16 Adsorption was carried out in the same manner as in Example 1 except that MOR type zeolite (Si / 2Al = 13) was used instead of H type MFI type zeolite, and yttrium nitrate was used instead of cerium nitrate. The agent was prepared. The amount of silver supported on this adsorbent was 8.1% by weight and that of yttrium was 4.5% by weight.

Example 17 An adsorbent was prepared in the same manner as in Example 1 except that FER type zeolite (Si / 2Al = 10) was used instead of H type MFI type zeolite. The silver and cerium supported on this adsorbent were 8.4% by weight and 4.6% by weight, respectively.

Example 18 An adsorbent was prepared in the same manner as in Example 1 except that ERI type zeolite (Si / 2Al = 6) was used instead of the H type MFI type zeolite. Silver and cerium supported on this adsorbent were 9.2% by weight and 4.8% by weight, respectively.

Example 19 An adsorbent was prepared in the same manner as in Example 1 except that LTL type zeolite (Si / 2Al = 6) was used in place of the H type MFI type zeolite. The amount of silver supported on this adsorbent was 9.1% by weight and that of cerium was 4.8% by weight.

Example 20 An adsorbent was prepared in the same manner as in Example 1 except that CHA type zeolite (Si / 2Al = 4) was used in place of the H type MFI type zeolite. The silver and cerium supported on this adsorbent were 9.5% by weight and 4.5% by weight, respectively.

Example 21 A powder of H-type MFI-type zeolite (Si / 2Al = 30) was stirred with an aqueous cerium nitrate solution having a concentration of 0.3M for 12 hours and then filtered to ion-exchange the zeolite with cerium. Carried. The powder obtained is dried and then calcined, then silver nitrate (AgNO ₃ ) at a concentration of 2.7 M and sodium pyrophosphate (PPN) at a concentration of 0.04 M.
After stirring in an aqueous solution of (Na ₄ P ₂ O ₇ ) for 12 hours,
The zeolite was loaded with silver and phosphorus by filtration. This zeolite was dried and then calcined to obtain an adsorbent. This adsorbent was coated exactly as in Example 1. The amount of silver supported on this adsorbent was 7.1% by weight, that of cerium was 4.1% by weight, and that of phosphorus was 0.2% by weight.

Example 22 An adsorbent was prepared in the same manner as in Example 21 except that BEA type zeolite (Si / 2Al = 25) was used instead of H type MFI type zeolite (Si / 2Al = 30). did. The silver supported in this adsorbent was 7.2% by weight,
Cerium was 3.9% by weight and phosphorus was 0.2% by weight.

Example 23 An adsorbent was prepared in the same manner as in Example 21 except that FAU type zeolite (Si / 2Al = 5.2) was used instead of the H type MFI type zeolite (Si / 2Al = 30). Was prepared. The amount of silver supported on this adsorbent was 8.9% by weight, cerium was 4.5% by weight, and phosphorus was 0.2% by weight.

Example 24 An adsorbent was prepared in the same manner as in Example 21, except that MOR type zeolite (Si / 2Al = 13) was used instead of H type MFI type zeolite (Si / 2Al = 30). did. The silver supported in this adsorbent was 8.0% by weight,
Cerium was 4.3% by weight and phosphorus was 0.2% by weight.

Example 25 A powder of H-type MFI type zeolite (Si / 2Al = 30) was stirred in an aqueous cerium nitrate solution having a concentration of 0.3 M for 12 hours and then filtered to ion-exchange the zeolite with cerium. Carried. The powder obtained was dried, calcined, and then stirred for 12 hours in an aqueous solution of silver nitrate having a concentration of 2.7 M and sodium pyrophosphate having a concentration of 0.04 M, and then filtered to obtain silver and Loaded with phosphorus.

This zeolite was dried and then calcined to obtain adsorbent A. Further, the FAU type zeolite was also subjected to the same treatment to obtain an adsorbent B. 50 parts by weight of the adsorbent A thus obtained, 50 parts by weight of the adsorbent B, 65 parts of silicogel (solid content 20%) and 65 parts of water were put into a magnetic pot, and the mixture was put in a vibration mill device for 40 minutes. Alternatively, it was mixed and pulverized for 6.5 hours in a universal ball mill to prepare a washcoat slurry.

The cordierite monolith carrier was suction-coated to remove excess slurry. Then, it dried and pre-baked at 400 degreeC for about 1 hour. This coated the zeolite with a coating amount of about 90 g / L. The above wash-coating, drying and calcination were repeated twice more to coat a total of about 200 g / L of zeolite, and calcination was carried out at 400 ° C. for 1 hour in an air atmosphere. The adsorbent contained 8.1% by weight of silver, 0.2% by weight of phosphorus, and 4% by weight of cerium.

Example 26 H-type MFI-type zeolite (Si / 2Al = 30) powder was stirred for 12 hours in an aqueous solution containing 0.3M cerium nitrate and 2.7M silver nitrate. After filtration, the zeolite was loaded with cerium and silver by ion exchange. The obtained powder was dried and then calcined to obtain an adsorbent. 100 parts by weight of this adsorbent, 65 parts of silicogel (solid content 20%) and 65 parts of water were put into a magnetic pot,
A wash coat slurry was prepared by mixing and grinding for 40 minutes with a vibration mill device or for 6.5 hours with a universal ball mill device.

The cordierite monolith carrier was subjected to suction coating to remove excess slurry. Then, it dried and pre-baked at 400 degreeC for about 1 hour. This coated the zeolite with a coating amount of about 90 g / L. The above wash-coating, drying and calcination were repeated twice more to coat a total of about 200 g / L of zeolite, and calcination was carried out at 400 ° C. for 1 hour in an air atmosphere. The amount of silver supported on this adsorbent was 7.2% by weight and that of cerium was 4% by weight.

Example 27 An adsorbent was prepared in the same manner as in Example 26 except that lanthanum nitrate was used instead of cerium nitrate. Silver loaded on this adsorbent was 7% by weight, and lanthanum was 3.
It was 9% by weight.

Example 28 Except that neodymium nitrate was used instead of cerium nitrate,
An adsorbent was prepared in exactly the same manner as in Example 26.
The amount of silver supported on this adsorbent was 7% by weight and that of neodymium was 3.9% by weight.

Example 29 An adsorbent was prepared in the same manner as in Example 26 except that yttrium nitrate was used instead of cerium nitrate. The silver and the yttrium supported on this adsorbent were 7% by weight and 4% by weight, respectively.

Example 30 An adsorbent was prepared in the same manner as in Example 26 except that BEA type zeolite (Si / 2Al = 25) was used instead of H type MFI type zeolite. 6.8% by weight of silver and 3.8% by weight of cerium supported on this adsorbent.
Met.

Example 31 Adsorption was carried out in the same manner as in Example 26 except that BEA type zeolite (Si / 2Al = 25) was used instead of H type MFI type zeolite and lanthanum nitrate was used instead of cerium nitrate. The agent was prepared. The amount of silver and lanthanum supported on this adsorbent was 7% by weight and 3.9% by weight, respectively.

Example 32 Adsorption was carried out in the same manner as in Example 26 except that BEA type zeolite (Si / 2Al = 25) was used instead of H type MFI type zeolite and neodymium nitrate was used instead of cerium nitrate. The agent was prepared. The amount of silver supported on this adsorbent was 7% by weight and that of neodymium was 3.9% by weight.

Example 33 Adsorption was carried out in the same manner as in Example 26 except that BEA type zeolite (Si / 2Al = 25) was used instead of H type MFI type zeolite and yttrium nitrate was used instead of cerium nitrate. The agent was prepared. The amount of silver supported on this adsorbent was 7% by weight and that of yttrium was 4.0% by weight.

Example 34 An adsorbent was prepared in the same manner as in Example 26 except that FAU type zeolite (Si / 2Al = 5.2) was used instead of the H type MFI type zeolite. The silver and cerium supported on this adsorbent were 8.9% by weight and 4.8% by weight, respectively.

Example 35 The same procedure as in Example 26 except that FAU type zeolite (Si / 2Al = 5.2) was used in place of the H type MFI type zeolite and lanthanum nitrate was used in place of the cerium nitrate. To prepare an adsorbent. Silver and lanthanum supported on this adsorbent were 9% by weight and 4.9% by weight, respectively.

Example 36 The same procedure as in Example 26 except that FAU type zeolite (Si / 2Al = 5.2) was used in place of the H type MFI type zeolite, and neodymium nitrate was used in place of the cerium nitrate. To prepare an adsorbent. The silver supported on this adsorbent was 8.8% by weight, and the neodymium was 4.9% by weight.

Example 37 The same procedure as in Example 26 except that FAU type zeolite (Si / 2Al = 5.2) was used in place of the H type MFI type zeolite, and yttrium nitrate was used in place of the cerium nitrate. To prepare an adsorbent. The silver supported on this adsorbent was 9.1% by weight, and the yttrium was 5.1% by weight.

Example 38 An adsorbent was prepared in the same manner as in Example 26 except that MOR type zeolite (Si / 2Al = 13) was used instead of the H type MFI type zeolite. 7.8 wt% silver and 4.4 wt% cerium supported in this adsorbent
Met.

Example 39 Adsorption was carried out in the same manner as in Example 26 except that MOR type zeolite (Si / 2Al = 13) was used in place of the H type MFI type zeolite, and lanthanum nitrate was used in place of the cerium nitrate. The agent was prepared. The amount of silver and lanthanum supported on this adsorbent was 8.1% by weight and 4.6% by weight, respectively.

Example 40 Adsorption was carried out in the same manner as in Example 26 except that MOR type zeolite (Si / 2Al = 13) was used instead of H type MFI type zeolite, and neodymium nitrate was used instead of cerium nitrate. The agent was prepared. The silver supported on this adsorbent was 7.9% by weight and the neodymium was 4.4% by weight.

Example 41 Adsorption was carried out in the same manner as in Example 26 except that MOR type zeolite (Si / 2Al = 13) was used in place of the H type MFI type zeolite, and yttrium nitrate was used in place of the cerium nitrate. The agent was prepared. Silver loaded on this adsorbent is 8.1% by weight, yttrium is 4.5% by weight.
Met.

Example 42 An adsorbent was prepared in the same manner as in Example 26 except that FER type zeolite (Si / 2Al = 10) was used instead of H type MFI type zeolite. Silver and cerium supported on this adsorbent are 8.4% by weight and 4.6% by weight, respectively.
Met.

Example 43 An adsorbent was prepared in exactly the same manner as in Example 26 except that ERI type zeolite (Si / 2Al = 6) was used in place of the H type MFI type zeolite. Silver and cerium supported on this adsorbent were 9.2% by weight and 4.8% by weight, respectively.

Example 44 An adsorbent was prepared in the same manner as in Example 26 except that LTL type zeolite (Si / 2Al = 6) was used in place of the H type MFI type zeolite. The amount of silver supported on this adsorbent was 9.1% by weight and that of cerium was 4.8% by weight.

Example 45 An adsorbent was prepared in exactly the same manner as in Example 26 except that CHA type zeolite (Si / 2Al = 4) was used instead of the H type MFI type zeolite. The silver and cerium supported on this adsorbent were 9.5% by weight and 4.5% by weight, respectively.

Example 46 A powder of H type MFI type zeolite (Si / 2Al = 30) was stirred in an aqueous cerium nitrate solution having a concentration of 0.3M for 12 hours and then filtered to ion-exchange the zeolite with cerium. Carried. The powder obtained is dried and then calcined, then silver nitrate (AgNO ₃ ) at a concentration of 2.7 M and sodium pyrophosphate (PPN) at a concentration of 0.04 M.
After stirring in an aqueous solution of (Na ₄ P ₂ O ₇ ) for 12 hours,
The zeolite was loaded with silver and phosphorus by filtration.

After drying this zeolite, it was calcined to obtain an adsorbent. This adsorbent was coated exactly as in Example 26. The silver supported in this adsorbent is 7.
1% by weight, cerium was 4.1% by weight, and phosphorus was 0.2% by weight.

Example 47 An adsorbent was prepared in the same manner as in Example 46 except that BEA type zeolite (Si / 2Al = 25) was used instead of H type MFI type zeolite (Si / 2Al = 30). did. The silver supported in this adsorbent was 7.2% by weight,
Cerium was 3.9% by weight and phosphorus was 0.2% by weight.

Example 48 An adsorbent was prepared in the same manner as in Example 46 except that FAU type zeolite (Si / 2Al = 5.2) was used instead of the H type MFI type zeolite (Si / 2Al = 30). Was prepared. The amount of silver supported on this adsorbent was 8.9% by weight, cerium was 4.5% by weight, and phosphorus was 0.2% by weight.

Example 49 An adsorbent was prepared by the same method as in Example 46 except that MOR type zeolite (Si / 2Al = 13) was used instead of H type MFI type zeolite (Si / 2Al = 30). did. The silver supported in this adsorbent was 8.0% by weight,
Cerium was 4.3% by weight and phosphorus was 0.2% by weight.

Example 50 A powder of H type MFI type zeolite (Si / 2Al = 30) was added to an aqueous solution of cerium nitrate having a concentration of 0.3M, silver nitrate having a concentration of 2.7M and sodium pyrophosphate having a concentration of 0.04M. After stirring for 12 hours, the mixture was filtered, and cerium was ion-exchanged and supported on the zeolite, and silver and phosphorus were also supported. This zeolite is dried and then calcined to obtain adsorbent C
Got Further, the FAU type zeolite was also subjected to the same treatment to obtain an adsorbent D.

50 parts by weight of the adsorbent C thus obtained, 50 parts by weight of the adsorbent D, and a silicone gel (solid content: 20
%) And 65 parts of water were put into a magnetic pot, and mixed and ground for 40 minutes with a vibration mill device or for 6.5 hours with a universal ball mill device to produce a washcoat slurry. The cordierite monolith carrier was suction-coated to remove excess slurry. Then, it was dried and calcined at 400 ° C. for about 1 hour. This coated the zeolite with a coating amount of about 90 g / L.

The above washcoating, drying and calcination were further repeated twice to coat a total of about 200 g / L of zeolite and calcination was carried out for 1 hour in an air atmosphere. The amount of silver supported in this adsorbent was 8.1% by weight, cerium was 4.0% by weight, and phosphorus was 0.2% by weight.

Comparative Example 1 A powder of H-type MFI type zeolite (Si / 2Al = 30) was stirred in an aqueous solution of silver nitrate having a concentration of 2.7 M for 12 hours and then filtered to support silver on the zeolite. After drying this zeolite, it was calcined to obtain an adsorbent.
100 parts by weight of the obtained adsorbent, silicon gel (solid content 20
%) And 65 parts of water were put into a magnetic pot, and coating was performed in exactly the same manner as in Example 1. The amount of silver supported in this adsorbent was 5.3% by weight.

Comparative Example 2 337.5 g of aluminum sulfate (18-hydrate) and sulfuric acid (9
7%) 362.5 g, cerium nitrate (hexahydrate) 232.
Water glass (J-sodium silicate) 5275.0 g and water 500, in which a solution obtained by mixing 7 g and water 7841 cc was used as solution E
The solution obtained by mixing 0 cc was designated as solution F. Sodium chloride 9
A solution prepared by mixing 87.5 g and 2300 cc of water was used as liquid G.

While stirring this G liquid at room temperature,
Solution and solution F were gradually added dropwise, and then sulfuric acid (48%) 60.
0 g was added. Mordenite powder 1 in this mixture
After adding 2.5 g, the mixture was placed in a 25-liter autoclave, the temperature was raised to 170 ° C. with stirring at a rotation speed of 300 ppm, and the reaction was carried out under self-pressure for 20 hours.

After cooling the resulting reaction mixture, the solid was filtered off. Then, 280 liters of water was added to the solid matter to wash with water, and filtration was repeated. The obtained solid material was dried at 120 ° C. for a whole day and night and then air-baked at 550 ° C. for 4 hours to obtain 1200 g of a crystalline aluminosilicate. Cerium-containing crystalline aluminosilicate according to X-ray diffraction measurement is a known ZSM having an MFI type structure.
It was similar to the -5 structure.

The cerium-containing crystalline aluminosilicate was stirred in an aqueous silver nitrate solution having a concentration of 2.7 M for 12 hours and then filtered to carry silver. The obtained powder was dried and then calcined to obtain an adsorbent. This adsorbent was put into a pot in exactly the same manner as in Example 1 and coated by the same method. The silver and the cerium supported on this adsorbent were 4.3% by weight and 3.2% by weight, respectively.

Comparative Example 3 A powder of H-type MFI-type zeolite (Si / 2Al = 30) was stirred in an aqueous solution of silver nitrate having a concentration of 2.7 M for 12 hours, filtered, and the zeolite was dried and then calcined. Then, the zeolite was loaded with silver. Then 0.3
After stirring in a cerium nitrate aqueous solution having a concentration of M for 12 hours, the mixture was filtered, and cerium was ion-exchanged and supported on the zeolite. The obtained powder was dried and then calcined to obtain an adsorbent. This adsorbent was coated exactly as in Example 1. The amount of silver and the amount of cerium supported on this adsorbent were 4.3% by weight and 4.2% by weight, respectively.

Comparative Example 4 An adsorbent was prepared in exactly the same manner as in Example 1 except that an aqueous silver nitrate solution having a concentration of 0.027M was used in place of the aqueous silver nitrate solution having a concentration of 2.7M. The amount of silver supported on this adsorbent was 0.05% by weight and that of cerium was 4.7% by weight.

Comparative Example 5 An adsorbent was prepared in exactly the same manner as in Example 1 except that a 7.5 M concentration silver nitrate aqueous solution was used in place of the 2.7 M concentration silver nitrate aqueous solution. The silver supported in this adsorbent is 2
It was 0.6% by weight and cerium was 3.9% by weight.

Comparative Example 6 0.000 in place of 0.3 M cerium nitrate aqueous solution
Example 1 except that a cerium nitrate aqueous solution having a concentration of 3M was used.
An adsorbent was prepared in exactly the same manner as in. The adsorbent supports 5.3% by weight of silver and 0.05% by weight of cerium.
Met.

Comparative Example 7 1.0M instead of 0.3M cerium nitrate aqueous solution
An adsorbent was prepared in exactly the same manner as in Example 1 except that an aqueous cerium nitrate solution having a concentration was used. The amount of silver supported on this adsorbent was 4.9% by weight and that of cerium was 14.6% by weight.

Comparative Example 8 An adsorbent was prepared in exactly the same manner as in Example 21, except that an aqueous solution of sodium pyrophosphate having a concentration of 0.001M was used in place of the aqueous solution of sodium pyrophosphate having a concentration of 0.04M. The amount of silver supported on this adsorbent was 7.2% by weight, that of cerium was 4.1% by weight, and that of phosphorus was 0.005% by weight.

Comparative Example 9 An adsorbent was prepared in exactly the same manner as in Example 21 except that a 1.4M concentration sodium pyrophosphate aqueous solution was used in place of the 0.04M concentration sodium pyrophosphate aqueous solution.
The amount of silver supported on this adsorbent was 4.3% by weight, that of cerium was 4.1% by weight, and that of phosphorus was 7.0% by weight.

Comparative Example 10 H-type mordenite (Si / 2Al = 13) powder was added,
After stirring for 12 hours in an aqueous silver nitrate solution having a concentration of 2.7 M, filtration, drying and firing were carried out to support silver on zeolite to obtain an adsorbent. 100 parts by weight of this adsorbent, 65 parts of colloidal ceria (solid content 20%) and 65 parts of water were put into a magnetic pot, and mixed and ground for 40 minutes with a vibration mill device or for 6.5 hours with a universal ball mill device. A washcoat slurry was prepared. The cordierite monolith carrier was suction-coated to remove excess slurry. Then, it dried and pre-baked at 400 degreeC for about 1 hour.

Thus, the zeolite was coated on the carrier at a coating amount of about 90 g / L. The above washcoat,
Repeated drying and baking two more times for a total of about 200 g / L
Of the above-mentioned zeolite was coated and calcined in an air atmosphere at 400 ° C. for 1 hour. The silver supported in this adsorbent is 4.6
% By weight, and cerium was 2.6% by weight.

Comparative Example 11 H-type MFI-type (Si / 2A1 = 30) powder was mixed with P ₂ O.
₅ was impregnated with a 1 wt% phosphoric acid aqueous solution, dried and calcined to support phosphorus on zeolite to obtain an adsorbent. 100 parts by weight of this adsorbent, silica sol (solid content 20%)
65 parts and 65 parts of water were put into a magnetic pot and mixed and ground for 40 minutes with a vibration mill device or for 6.5 hours with a universal ball mill device to produce a washcoat slurry. The cordierite monolith simple substance was subjected to suction coating to remove excess slurry. Then, it dried and pre-baked at 400 degreeC for about 1 hour. As a result, the zeolite was coated at a coating amount of about 90 g / L as a single substance. The above wash coating, drying and calcination were repeated twice more to coat a total of about 200 g / L of zeolite and calcination was carried out at 400 ° C. for 1 hour in an air atmosphere. The supported silver in this adsorbent was 4.6% by weight and the phosphorus was 0.85% by weight.

Test Example Using the adsorbents obtained in Examples 1 to 50 and Comparative Examples 1 to 11, HC adsorption / purification characteristics were evaluated under the following evaluation conditions. The results are shown in Tables 1, 2 and 3, and the evaluation results are shown in Table 4.
And 5 are shown.

[0103]

[Table 1]

[0104]

[Table 2]

[0105]

[Table 3]

[0106]

[Table 4]

[0107]

[Table 5]

In the evaluation, as shown in FIG. 1, a Pt-Rh-based catalyst was placed as the pre-three-way catalyst 3 (0.5 L) in the exhaust manifold 2 of the engine 1, and the underfloor catalyst 5 (1.3 L) was used. Adsorbent 4 before the Pt-Rh catalyst
Using an exhaust gas purifying apparatus equipped with (1.3 L), performance comparison was made with the case without an adsorbent.

In the evaluation, the following two items were examined. (1) In order to evaluate the adsorption performance of hydrocarbons discharged at the time of engine start-up after endurance, the emission reduction rate during Abag 0 to 125 seconds was measured. (2) There is no emission reduction effect even if the temporarily adsorbed hydrocarbon is desorbed before the three-way catalyst downstream of the adsorbent is activated. Therefore, in order to evaluate the desorption suppressing ability and the self-cleaning ability by the adsorption catalyst, the emission reduction rate during Abag 0 to 505 seconds was measured.

Evaluation conditions Catalyst capacity 1.3L Evaluation vehicle V-type 6-cylinder 3000cc engine manufactured by Nissan Motor Co., Ltd. Evaluation mode FTP75 mode (Abag) Hydrocarbons (in the gas at the catalyst inlet) exhausted when the engine is started C ₂ 〜C ₃ 21.2% C ₄ 〜C ₆ 33.0% C ₇ 〜C ₉ 45.8% Engine durable product Adsorbent 700 ° C × 50h Nissan Motor Co., Ltd. V type 8 cylinder 4400cc engine durable product Repeat 60 seconds (cruising) + 5 seconds (fuel cut)]

[0111]

INDUSTRIAL APPLICABILITY The hydrocarbon adsorbent of the present invention is applied to crystalline aluminosilicate as an adsorbent for adsorbing unburned hydrocarbons contained in exhaust gas discharged from an internal combustion engine such as an automobile.
By carrying Group B and silver and further performing an ion exchange method as a Group IIIB supporting method, it is possible to prevent the exhaust gas purification performance from being deteriorated due to contact with the exhaust gas at high temperature, and to prevent hydrocarbons after contact with the high temperature gas. It is possible to maintain the adsorptive and desorbing ability of, and also to maintain the heat resistance of the metal.

[Brief description of drawings]

FIG. 1 is a system diagram of an exhaust gas purification device used for a test.

[Explanation of symbols]

 1 engine 2 exhaust manifold 3 pre three way catalyst 4 adsorbent 5 underfloor three way catalyst

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takuya Ikeda 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. (72) Inventor Takeshi Masuda 2 Takara-cho, Kanagawa-ku, Yokohama, Nissan Nissan Motor Co., Ltd.

Claims (6)

[Claims] 1. A hydrocarbon adsorbent containing silver, Group IIIB of the Periodic Table and a crystalline aluminosilicate, wherein the Group IIIB is ion-exchanged with the crystalline aluminosilicate. 2. The crystalline aluminosilicate is MFI, B
EA, FAU, MOR, FER, ERI, LTL and C
At least one selected from the group consisting of HA-type zeolites
The hydrocarbon adsorbent according to claim 1, which is a seed. 3. The hydrocarbon adsorbent according to claim 1, wherein Group IIIB is at least one selected from the group consisting of cerium, lanthanum, neodymium and yttrium. 4. III. To crystalline aluminosilicate
The hydrocarbon adsorbent according to claim 1, wherein the group B loading is ion-exchanged before the silver loading or simultaneously with the silver loading. 5. The silver content is in the range of 0.1 to 15% by weight, and the Group IIIB loading is in the range of 0.1 to 10% by weight. Hydrocarbon adsorbent. 6. The hydrocarbon adsorbent according to claim 1, wherein the supported amount of phosphorus is in the range of 0.01 to 5% by weight.