JPH0810613A - Adsorbing material for purifying exhaust gas of car - Google Patents

Abstract

PURPOSE:To enhance HC adsorbing capacity and to improve the purifying capacity of HC in exhaust gas of car by constituting an adsorbing material of zeolite containing at least one kind of an ion wherein the electronegativity of an element is a specific value or more. CONSTITUTION:The adsorbing material for purifying exhaust gas of a car is constituted of zeolite containing at least one kind of an ion wherein the electronegativity of an element is 1.40 or more. The adsorbing material may be constituted of zeolite containing at least one kind of an ion being a soft acid or intermediate acid of which the electronegativity of an element is 1.40 or more. Further, the adsorbing material may be constituted of zeolite containing at least one of ions of group IB elements (Cu, Ag, Au). The SiO2/Al2O3mol ratio of zeolite is set to 40 or more. As zeolite, either one of ZMS-5, USY and beta-zeolite is used. When adsorbing capacity is evaluated, a tester equipped with an analyzer or a computer shown by the drawing is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zeolite adsorbent for purifying automobile exhaust gas.

[0002]

2. Description of the Related Art A catalytic converter used for purifying exhaust gas from an automobile or the like needs to be heated to a predetermined temperature or higher in order for the catalyst to exert a catalytic action. Therefore, at the time of starting the vehicle where the temperature of the catalyst has not risen sufficiently (hereinafter referred to as cold start), unpurified exhaust gas harmful components are released into the atmosphere. Hydrocarbons (HC) and carbon monoxide (C
Among harmful components such as O) and nitrogen oxides (NO _x ), HC is being regulated in particular, and a large amount is generated at the cold start. Therefore, the release of HC at the cold start is suppressed. Has become an important technical issue.

Recently, attempts have been made to purify exhaust gas by utilizing the HC adsorbing action of zeolite. For example, in Japanese Patent Laid-Open No. 2-75327, a purifying catalyst is arranged in the exhaust system and adsorbed upstream thereof. An automobile exhaust gas purifying device in which Y-type zeolite or mordenite is arranged as a material is shown. JP-A 2-111438 discloses an HC adsorbent obtained by coating a carrier with mordenite or Y-type zeolite containing a cation such as an alkali metal cation and then exchanging the cation for a hydrogen ion. There is.

[0004]

However, the converter using zeolite as the adsorbent is not suitable for the zeolite H
There is a large difference between the C desorption temperature and the catalytic action temperature, the desorption of HC starts before the temperature of the zeolite adsorbent reaches the catalytic action temperature, and thermal degradation occurs due to exposure to high temperatures in the exhaust gas. That is, moisture contained in the exhaust gas is preferentially adsorbed to reduce the amount of HC adsorbed. Many types of HC are generated at cold start, but it is difficult to adsorb all types of HC. Have problems such as.

For example, in the device described in the above-mentioned Japanese Patent Application Laid-Open No. 2-75327, H 2 is adsorbed on the upstream side of the purification catalyst.
Even if C is adsorbed, HC is desorbed from the adsorbent with warming up before the purification catalyst reaches a sufficient working temperature, and as a result, a considerable amount of HC passes through the purification catalyst without being purified. There is. Further, in the above-mentioned JP-A-2-75327 and JP-A-2-111438, since mordenite or Y-type zeolite is used as the zeolite, the thermal durability is poor and structural destruction occurs in automobile exhaust gas. It is easy to occur. Furthermore, since these zeolites are hydrophilic, there is a problem that water is preferentially adsorbed in automobile exhaust gas and the amount of adsorbed HC decreases.

The present invention has been made in view of the problems associated with these conventional zeolite adsorbents, and has improved the adsorption power of HC, heat resistance, etc., and has greatly improved the purification capacity of HC in exhaust gas. An object is to provide an adsorbent for purifying automobile exhaust gas.

[0007]

According to the present invention, there is provided an adsorbent for purifying automobile exhaust gas, characterized by comprising a zeolite containing at least one kind of ion having an electronegativity of 1.40 or more. Provided. Further, according to the present invention, an adsorbent for purifying automobile exhaust gas, characterized by comprising a zeolite containing at least one kind of ion which is a soft acid having an electronegativity of 1.40 or more or an intermediate acid, Will be provided. Further, according to the present invention, there is provided an adsorbent for automobile exhaust gas purification, characterized by comprising a zeolite containing at least one kind of ion of a Group IB element (Cu, Ag, Au) of the periodic table. Further, according to the present invention,
Provided is an adsorbent for purifying automobile exhaust gas, which is characterized by comprising a zeolite containing at least Ag ions. Further, according to the present invention, at least Ag ions and C
Provided is an adsorbent for purifying automobile exhaust gas, which is composed of zeolite containing u ions. Furthermore,
According to the present invention, there is provided an adsorbent for automobile exhaust gas purification, which is obtained by coating a honeycomb structure with at least one of the adsorbents. Furthermore, according to the present invention, an adsorbent for purifying automobile exhaust gas, which is formed by forming at least one powder raw material of the adsorbent into a honeycomb shape and sintering the same.
Will be provided.

[0008]

The adsorbent for purifying automobile exhaust gas of the present invention is a zeolite containing at least one ion having an electronegativity of 1.40 or more, preferably 1.80 or more. As described above, since an ion having a high electronegativity of an element easily attracts an electron, the interaction between the zeolite and the HC molecule is increased by including the ion in the zeolite, and as a result, the adsorption power of HC is improved. And then H
As the C adsorption amount increases, the HC desorption temperature also increases.

Ions having an electronegativity of 1.40 or more include Al, Ti, V, Mn, Fe, Co, Ni,
Ions such as Cu, Zn, Pd, Ag, Pt, and Au can be mentioned. Among these, a soft acid or an intermediate acid is preferable. Here, the “soft acid or intermediate acid” is a reaction (M → M ^{n +} + n) for hydrating and ionizing a gaseous metal simple substance M.
e ^- the value of the enthalpy ΔH ⁰ divided by the valence n of) ΔH ⁰ /
An ion having an n of 1.8 (eV) or more. Comparing metals having the same valence n, the softer metal has a larger positive ionization energy. Further, the enthalpy of hydration has a larger negative value for a softer metal in a solvent having a large polarity such as water. In practice, taking into account the difference in the valence number n, the larger ΔH ⁰ / n is, the softer the metal ion is, and the smaller it is, the harder the metal ion is. In the present invention, ΔH ⁰ / n is 1.8 (e
V) or more, and more preferably 3.0 (eV) or more. Specifically, Co ²⁺ , Ni ²⁺ , Zn
²⁺ , Cu ²⁺ , Cu ⁺ , Ag ⁺ , Au ⁺ , Fe ^{2+ and the} like. The softer the hardness as an acid, the larger the atomic radius and the higher the polarizability. Therefore, by including at least one kind of such a soft acid or an ion that is an intermediate acid, it is possible to form a mixture with HC such as toluene or propylene. The overlapped area becomes larger and the suction force becomes stronger.

Further, by containing at least one kind of ion of the IB group element (Cu, Ag, Au) of the periodic table as the above-mentioned ion, a high adsorption property to HC is exhibited even in the presence of water, and further, these ions are exhibited. Ions also exhibit a catalytic action at a temperature of 150 ° C. or higher. Among these IB group element ions, Cu and Ag ions are preferable, and Ag ions are particularly preferable in the sense that more HC is adsorbed at higher temperatures. Furthermore, Ag ions under conditions in which O ₂ is not present, to show the same adsorption amount in the case where O ₂ is present, excellent adsorption capacity even under conditions likely be exposed to an atmosphere of the fuel-rich, such as in automobile exhaust gas Indicates. Further, when Ag ions and Cu ions are simultaneously present in the zeolite, the adsorption performance improving effect of Ag ions and Cu
It is possible to take advantage of both the adsorption and catalytic performance improving effects of ions, and exhibits excellent purification performance in a wide temperature range from low temperature to high temperature. Further, the presence of two kinds of ions prevents the respective ions from aggregating, which leads to improvement in heat resistance.

Next, as the zeolite containing the above-mentioned ions, from the viewpoint of heat resistance, SiO ₂ / Al ₂
A high silica zeolite having an O ₃ ratio of 40 or more, preferably 80 or more, and more preferably 100 or more in terms of molar ratio can be suitably used. When the above ions are supported on zeolite by an ion exchange method, it is preferable that the SiO ₂ / Al ₂ O ₃ ratio is small, but since the adsorbent of the present invention is used in high temperature exhaust gas, heat resistance is prioritized. It is preferable to use high silica zeolite in order to prevent thermal deterioration of the adsorbent. It has been confirmed that the SiO ₂ / Al ₂ O ₃ ratio should be 40 or more when used by bypassing or installed under the floor. Specific examples of such high-silica zeolite include ZSM-5, USY, β-
Zeolite may be mentioned, and it is preferable that the above-mentioned ions be contained in any of these to form the adsorbent of the present invention.

Examples of the form of containing the above-mentioned ions in the zeolite include carrying by the ion exchange method and carrying by the impregnation method, and the existence position (coordination form) of the ions carried by the zeolite is zeolite oxygen. On the other hand, a plane four-coordination is preferable from the viewpoint of improving the HC adsorption capacity. Although the cause is unknown, it is considered that the HC adsorbing power is improved because the voids are present in the upper and lower portions and the HCs are easily approached to each other when they are coordinated on a plane. In order to make the position of the ions plane four-coordinate with respect to the zeolite oxygen, the size of the anion of the metal salt used to support the ions on the zeolite should be three-dimensionally increased, or the salt with a low degree of ion dissociation should be used. By using
It is possible to use a method of increasing the number of ions existing in the plane four-coordinate position by making it difficult for the cations to approach the sterically hindered five-coordinate or six-coordinate sites.
As the metal salt used at this time, specifically, an organic acid salt such as acetate is preferable.

Further, since the effect of improving the desorption temperature of HC is small when the ion content of the zeolite is small, the ion content of the zeolite is preferably 20% or more with respect to the Al atom in the zeolite. It is more preferably 40% or more. When the ions are contained in the zeolite by ion exchange, the ion exchange rate can be increased by increasing the concentration of the metal salt solution used during ion exchange or lengthening the ion exchange time. In addition, in the case of repeating the ion exchange with a metal salt solution of a certain concentration for a certain period of time, filtering, and then again performing the same ion exchange using a new metal salt aqueous solution,
The ion exchange rate can be increased by increasing the number of times of ion exchange with the new liquid.

Further, in the present invention, in the zeolite, Mg, Ca, Sr, Ba, Y, La, Ti and C are further added.
At least one ion selected from various ions of e, Mn, Fe, Cr, Ni, Zn, preferably Mg, C
It is desirable to contain at least one kind of ion among a, Fe, and Cr ions because heat resistance is improved. Further, when at least one noble metal is further contained in the zeolite, higher catalytic activity is exhibited and an excellent purifying action is exhibited in a wide temperature range from low temperature to high temperature. In this case, Pt, Rh and Pd can be preferably used as the noble metal.
Further, the noble metal is preferably supported by the ion exchange method from the viewpoint of thermal stability.

The form of the adsorbent of the present invention is not particularly limited, and it may be used in any form such as beads, pellets, honeycombs, rings, etc. However, it is made honeycomb in terms of pressure loss and thermal shock resistance. Is preferred. Specifically, at least one of the adsorbents made of zeolite containing ions described above is coated on a honeycomb structure (single body) made of cordierite, ferritic stainless steel, or the like, or It is preferable that at least one of the powder raw materials is formed into a honeycomb shape and is sintered. The “honeycomb structure” refers to a structure having a large number of through holes that are partitioned by partition walls and are substantially parallel to the gas flow direction.

Zeolites such as ZMS-5, USY and β-zeolite can be used not only in one kind but also in a combination of plural kinds, and when they are coated on the honeycomb structure, they are mixed or layered. be able to.
For example, ZMS-5, which has relatively small pores with a pore size of about 0.55 nm, is advantageous for adsorbing HC of a small molecule having a toluene molecular size or less, and a relatively large pore with a pore size of about 0.74 nm. USY with is advantageous for adsorbing large-molecular HC above m-xylene. Further, since β-zeolite has bimodal pores having pore diameters of about 0.55 nm and about 0.70 nm, both small molecules and large molecules can be adsorbed relatively well. As described above, almost all of various HCs having different molecular diameters can be adsorbed by arbitrarily combining a plurality of types of zeolites having different pore diameters.

[0017]

The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited to these examples.

Examples 1 to 19 and Comparative Examples 1 to 7 [Preparation of adsorbents] Tables 2 to 4 were prepared by the ion exchange method or impregnation method using the various zeolites and metal salts listed in Table 1 below.
Various adsorbents (Examples 1 to 19 and Comparative Example 1)
~ 7) were produced. The preparation procedure by the ion exchange method or the impregnation method is shown below.

Preparation procedure by the ion exchange method: Zeolite powder, metal salt and deionized water are weighed in predetermined amounts and mixed so that the solution concentration is 0.05 to 0.2 mol / l, and the mixture is kept at 80 to 90 ° C. While maintaining the temperature, an ion exchange treatment is carried out for 2 hours (one time) with stirring. After filtration, perform the same ion exchange again using the new solution.
Repeat 5 times. Then use deionized water at 50 ° C. for 15
After cleaning for 5 minutes (per time), filtration is required
After repeating 10 times, it is dried in air at 100 ° C. for 10 hours. Further, it is calcined in the air at 550 ° C. for 1 hour to obtain ion-exchanged zeolite powder ion-exchanged with desired ions.

Alumina sol having a solid content of 2.5% by weight of alumina and water were added to the obtained ion-exchanged zeolite powder,
Wet disintegration in a ball mill for 20 hours to obtain a supporting slurry. Next, a cordierite honeycomb simple substance manufactured by Nippon Insulators Co., Ltd. (square cell, cell density 400 cells / in ² (62
Cell / cm ² ), rib thickness 4 mil (102 μm), honeycomb capacity 2
6 cc) is dipped in the obtained supporting slurry to coat it so that the supported amount is 0.16 g / cc, dried, and then calcined in the atmosphere at 550 ° C. for 1 hour to obtain an adsorbent.

Preparation procedure by impregnation method: zeolite powder,
Predetermined amounts of metal salt and deionized water are prepared and mixed so that the solution concentration is 0.05 to 0.2 mol / l.
The temperature is kept at ˜90 ° C. and the impregnation treatment is performed for 2 hours.
Then, it is dried in air at 100 ° C. for 10 hours, and is further calcined in air at 550 ° C. for 1 hour to obtain an ion-supporting zeolite powder in which desired ions are impregnated and supported. The obtained ion-supported zeolite powder is coated on a honeycomb simple substance and fired in the same manner as in the production procedure by the above-mentioned ion exchange method to obtain an adsorbent.

[0022]

[Table 1]

[Evaluation of Adsorbent] The adsorbents of Examples 1 to 19 and Comparative Examples 1 to 7 obtained as described above were measured in exhaust gas under various measurement conditions (exhaust gas atmosphere, adsorbent inlet gas temperature). The adsorption rate of HC was investigated and the adsorption performance was evaluated. For the evaluation, a test apparatus as shown in FIG. 1 was used, and HC: 4500 ppm (carbon standard), CO ₂ : 16, which simulated the actual exhaust gas at cold start, as the evaluation gas.
%, O ₂ : 0.77%, CO: 2%, H ₂ : 0.33%,
H ₂ O: 10%, NO: 1500 ppm, and residual amount of N ₂
A model gas having a composition consisting of (however, H ₂ O and NO may not be contained; see Tables 2 to 4) was used. This model gas was passed through the adsorbent at a total gas flow rate of 17 l / min, and the amount of HC discharged in the gas after passing through the adsorbent was measured for 150 seconds. The adsorption ratio was calculated using the following formula 1. The obtained results are shown in Tables 2-4.

[0024]

[Equation 1]

[0025]

[Table 2]

[0026]

[Table 3]

[0027]

[Table 4]

As can be seen from the results shown in Tables 2 to 4, the adsorbents of Examples 1 to 19 made of zeolite containing ions having an electronegativity of 1.4 or more have an electronegativity of element. Compared to the adsorbents of Comparative Examples 1 to 7 which consisted of zeolite containing less than 1.4 ions, the adsorbent showed higher adsorption performance, and the difference was particularly remarkable on the high temperature side. Also, among the examples, ions that are soft acids or intermediate acids, especially I
Those containing ions of the group B element and those to which ions such as noble metals were added exhibited particularly good adsorption ability.

Examples 20 to 27 [Preparation of adsorbent] Zeolite type and SiO ₂ / Al ₂ O
_In order to investigate the influence of the ₃ ratio on the adsorption performance, particularly durability, the adsorbents of Examples 20 to 27 shown in Table 5 were prepared according to the production procedure shown in Examples 1 to 19 and Comparative Examples 1 to 7 above. Obtained. The metal salt used for ion exchange or impregnation was Ag.
Acetate was used for both ⁺ and Cu ²⁺ .

[Evaluation of Adsorbent] The adsorbents of Examples 20 to 27 obtained as described above were evaluated for HC adsorption performance in the same manner as in Examples 1 to 19 and Comparative Examples 1 to 7. Then
In order to examine the thermal durability of the adsorbent, an endurance test was conducted in which an engine with a displacement of 2000 cc was used and the adsorbent was operated at an inlet gas temperature of 750 ° C. for 100 hours. 19, the same evaluation as in Comparative Examples 1 to 7 was performed. The obtained results (before and after endurance) are shown in Table 5.

[0031]

[Table 5]

From the results shown in Table 5 above, SiO ₂ / Al ₂
When zeolite having a high O ₃ ratio was used, the decrease in adsorption rate at 200 ° C. after the durability test was smaller than that before the durability test, and the durability was excellent.

Examples 28 to 31 [Preparation of adsorbent] Influence of coordination form of ions contained in zeolite (ratio of plane four-coordinate (relative to zeolite oxygen) to the whole coordination) on adsorption performance In order to investigate, the adsorbents of Examples 28 to 31 shown in Table 6 were obtained according to the production procedures shown in Examples 1 to 19 and Comparative Examples 1 to 7 above. However, Examples 28, 30 and 31 used copper acetate as the Cu ²⁺ salt, and Example 29 used copper nitrate as the Cu ²⁺ salt. The coordination form in the table is "Cu ²⁺ -cation
location and reactivity in mordenite and ZSM-5: e.
sr study "AV Kucherov, ZEOLITES, Vol. 5 (1985).

[Evaluation of Adsorbent] The adsorbents of Examples 28 to 31 obtained as described above were evaluated for HC adsorption performance in the same manner as in Examples 1 to 19 and Comparative Examples 1 to 7. The obtained results are shown in Table 6.

[0035]

[Table 6]

As can be seen from the results shown in Table 6 above, Examples 28, 30, and 31 having a higher proportion of plane four-coordination exhibited better adsorption performance than Example 29 having a lower proportion of plane four coordination. It was

Examples 32 to 45, Comparative Examples 8 to 11 [Preparation of Adsorbent] Various secondary ions for the purpose of improving heat resistance (in the right column of the column of “ion type and ion abundance” in Table 7). Example 1 above to investigate the effect of adding
-19 and Table 7 according to the manufacturing procedure shown in Comparative Examples 1-7.
The adsorbents of Examples 32 to 45 and Comparative Examples 8 to 11 shown in Table 1 were obtained (for the "type of zeolite" in Table 7, see Table 1 above).

[Evaluation of Adsorbents] With respect to the adsorbents of Examples 32 to 45 and Comparative Examples 8 to 11 obtained as described above,
The HC adsorption performance before and after the durability test was evaluated in the same manner as in Examples 20 to 27. The results obtained are shown in Table 7.

[0039]

[Table 7]

As can be seen from the results shown in Table 7 above, Examples 32 to 4 containing the ions having electronegativity of 1.4 or more were included.
In Comparative Example 5, the deterioration of the adsorption performance after endurance was relatively small, and the heat resistance improving effect by the addition of the second ion was recognized, but Comparative Example 8 in which the electronegativity of the element was less than 1.4 was included. In Nos. 11 to 11, there was a large drop in adsorption performance after endurance, and sufficient heat resistance could not be obtained even by adding the second ion.

Example 46 [Preparation of Adsorbent] Ion-exchanged zeolite powder was obtained in the same manner as in Example 1. Then, to 70% by weight of the obtained ion-exchanged zeolite powder, 5% by weight of a polysaccharide binder and 25% by weight of bentonite were added and mixed, and 40% by weight of deionized water was further added and kneaded, followed by extrusion molding. A honeycomb molded body was obtained. This was fired in air at 500 ° C. for 3 hours to obtain an adsorbent of Example 46 in which a honeycomb structure was composed of ion-exchanged zeolite itself.

[Evaluation of Adsorbent] For the adsorbent of Example 46 obtained as described above, Examples 1 to 19 and Comparative Example 1
The HC adsorption performance was evaluated in the same manner as in the above. The model gas used for the evaluation was H ₂ O: 10% and NO: 1500p.
It includes pm together. Table 8 shows the obtained results.

[0043]

[Table 8]

As shown in the results shown in Table 8 above, the adsorbent composed of the ion-exchanged zeolite itself without using the carrier also exhibited good adsorption performance.

Examples 47 and 48 [Preparation of Adsorbent] In order to examine the change in the adsorption ratio of zeolite depending on the presence or absence of oxygen in the exhaust gas, the above Example 1 was used.
19 and Table 9 according to the manufacturing procedure shown in Comparative Examples 1 to 7.
The adsorbents of Examples 47 and 48 shown in Table 1 were obtained (for the "type of zeolite" in Table 9, see Table 1 above).

[Evaluation of Adsorbent] The adsorbents of Examples 47 and 48 obtained as described above were evaluated for HC adsorption performance in the same manner as in Examples 1 to 19 and Comparative Examples 1 to 7. The model gas used for the evaluation is Examples 1 to 19 and Comparative Examples 1 to 7.
In some cases, 0.77% O ₂ was not added in order to clarify the effect of oxygen in the gas.
The results obtained are shown in Table 9.

[0047]

[Table 9]

As can be seen from the results shown in Table 9 above, in the case of the adsorbent of Example 48 containing Cu ²⁺ by ion exchange, the adsorption ratio at the inlet gas temperature of 300 ° C. or higher decreased under the condition of no O _2. However, in contrast, in the case of the adsorbent of Example 47 containing Ag ⁺ by ion exchange,
The adsorption ratio did not decrease even under the condition of no O ₂ . Therefore, it can be said that the zeolite containing Ag ⁺ exhibits good adsorption performance even in a fuel-rich atmosphere such as automobile exhaust gas.

[0049]

As described above, the adsorbent for purifying automobile exhaust gas according to the present invention has excellent HC adsorbing performance, and when it is used in combination with a catalytic converter or the like, it is possible to obtain H in the atmosphere.
The amount of C emission can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a test apparatus used for evaluation of an adsorbent in an example.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display area C01B 39/02

Claims (13)

[Claims] 1. An adsorbent for purifying automobile exhaust gas, which comprises a zeolite containing at least one kind of ion having an electronegativity of 1.40 or more. 2. An adsorbent for automobile exhaust gas purification, which comprises a zeolite containing at least one kind of ion which is a soft acid having an electronegativity of an element of 1.40 or more or an intermediate acid. 3. A Group IB element of the periodic table (Cu, Ag, A
An adsorbent for automobile exhaust gas purification, which comprises a zeolite containing at least one ion of u). 4. An adsorbent for automobile exhaust gas purification, characterized by comprising zeolite containing at least Ag ions. 5. An adsorbent for purifying automobile exhaust gas, characterized by comprising zeolite containing at least Ag ions and Cu ions. 6. The adsorbent for purifying automobile exhaust gas according to claim 1, wherein the zeolite has a SiO ₂ / Al ₂ O ₃ ratio of 40 or more in a molar ratio. 7. The type of zeolite is ZSM-5, U
The adsorbent for automobile exhaust gas purification according to any one of claims 1 to 6, which is either SY or β-zeolite. 8. The adsorbent for purifying automobile exhaust gas according to claim 1, wherein the ions are present in the zeolite in a plane four-coordinate with respect to zeolite oxygen. 9. The ion content of the zeolite is 20% or more with respect to the Al atoms in the zeolite.
8. An adsorbent for purifying automobile exhaust gas according to any one of 8. 10. The zeolite further contains Mg and C.
a, Sr, Ba, Y, La, Ti, Ce, Mn, Fe,
The adsorbent for automobile exhaust gas purification according to any one of claims 1 to 9, which contains at least one ion selected from various ions of Cr, Ni, and Zn. 11. The adsorbent for purifying automobile exhaust gas according to claim 1, wherein the zeolite further contains at least one noble metal. 12. An adsorbent for purifying automobile exhaust gas, comprising a honeycomb structure coated with at least one of the adsorbents according to claim 1. 13. An adsorbent for purifying automobile exhaust gas, which is obtained by forming at least one powder raw material of the adsorbents according to any one of claims 1 to 11 into a honeycomb shape and sintering it.