JPH07308573A - Treating agent for air pollution material - Google Patents

Abstract

PURPOSE:To obtain a treating agent for air pollution material capable of treating the air pollution material in a wide range by incorporating at least one of manganese dioxide having spinel type crystalline structure or a spinel type hydrogenated manganese oxide, containing hydrogen together with manganese and oxygen as the substantial structural components, into the agent as an active component. CONSTITUTION:This treating agent contains at least one of MnO2 having spinel type crystalline structure or the spinel type hydrogenated manganese oxide, containing hydrogen together with Mn and oxygen as the substantial structural components, as the active component. And MnO2 having spinel type crystalline structure and/or the hydrogenated manganese oxide contains metals (e.g. iron) except Mn with Mn and oxygen as the substantial structural component and is obtained by removing or replacing a part or total of metallic ion of a spinel type metal/manganese double oxide having +3 and/or +4 oxidation number of Mn by hydrogen ion. As a result, sulfur oxides, nitrogen oxides or oxidants in the air are adsorbed and removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an agent for treating air pollutants, which is an atmosphere such as sulfur oxides, nitrogen oxides and oxidants which are generated from an unspecified number or specified equipment / equipment and are contained in the atmosphere. Contaminants are effectively adsorbed and removed, or converted into substances that can be easily removed by other removal means before being released, or related substances that promote them at the same time. Indoors in areas with poor atmospheric environment The present invention relates to a treatment agent for air pollutants that can be used for the prevention of health hazards and the prevention of corrosion of structures, etc. by cleaning the ventilation gas from space and pollutant sources.

[0002]

2. Description of the Related Art Conventionally, an activated carbon filter has been frequently used to purify polluted air (see Carbon Material Society of Japan, Activated Carbon-Basics and Applications-Section 6.2.3, Kodansha, (1975)). Typical air pollutants whose emission limits are wide range include sulfur oxides (such as sulfur dioxide), nitrogen oxides (such as nitric oxide and nitrogen dioxide), and oxidants (such as ozone).

Of these, if nitric oxide, which is low in adsorptivity and reactivity, is removed, it can be removed by activated carbon suitable for each target substance (for example, one that has been subjected to treatment such as chemical impregnation). In addition, in order to remove nitric oxide, which occupies most of the nitrogen oxides, it is pre-oxidized to nitrogen dioxide by various oxidizing agents (such as ozone, permanganate and chlorite), and then activated carbon is adsorbed. A method of removing with a chemical is considered.

For example, some of the inventors of the present invention have proposed activated carbon that effectively adsorbs nitric oxide (Japanese Patent Application No. 3-3523).
No. 41,). Further, some of the inventors of the present invention are hydrogenated manganese oxides having a spinel type crystal structure containing hydrogen as an essential constituent, and manganese having an average valence of more than 3.5 is highly active as a nitric oxide scavenger. Was found (Japanese Patent Laid-Open No. 5-253474).

This removing agent is specifically Li _1.33 Mn _1.67 O ₄
Li _(1.33-X) H _X Mn _1.67 O ₄ (0 <X ≤ 1.33) in which a part or all of the lithium ions of is replaced by hydrogen ions, preferably in an amount of 60 mass% or more, and X is preferably 0.9 or more. More preferably, it is an oxide of 1.2 or more, and has a property of adsorbing a part of nitric oxide, oxidizing a part of it to nitrogen dioxide, and then releasing it.

Practically, when the treated air is dehumidified in advance, it is used as a nitric oxide adsorbent, and in the case of treatment without dehumidification, a nitric oxide adsorbent is provided in the downstream side so as to remove the monoxide. Nitrogen can be effectively removed (Japanese Patent Application No. 4-252872).

[0007]

With the progress of air pollution, it is becoming important to comprehensively remove various harmful components in order to prevent health problems and prevent corrosion of structures and the like. In the case of comprehensively and effectively treating multiple removed harmful target components with activated carbon, it is necessary to use a combination of various activated carbons suitable for each target, and it is not always effective like nitric oxide. Some objects cannot be expected to be removed.
The method of oxidizing nitrogen dioxide by using an oxidizing agent such as ozone and then removing it has problems in addition to its practical efficiency, such as removal of excess ozone and disposal of used oxidizing agent.

An activated carbon for adsorbing nitric oxide has already been proposed in Japanese Patent Application No. 3-352341, but its adsorbing capacity is not such that adsorption can be continued for a long period of time, and regeneration at regular intervals is required. It is assumed to be used repeatedly. Therefore, it is not practical if the local reproduction cannot be performed due to the limitation of the installation place.

Further, the nitric oxide scavenger proposed in Japanese Patent Application Laid-Open No. 5-253474 is limited to a part of manganese oxide having a spinel type crystal structure, but a compound having other constitution Is not mentioned, nor is it possible to process components other than nitrogen oxides.

An object of the present invention is to solve the above conventional problems and to provide an air pollutant treating agent capable of treating air pollutants in a wider range.

[0011]

In order to achieve the above object, the inventors of the present invention have conducted extensive studies and as a result, as the active ingredient, manganese dioxide having a spinel type crystal structure, or hydrogen in addition to manganese and oxygen. The present invention has been completed based on the finding that the one containing at least one of the spinel-type hydrogenated manganese oxides, which is contained as an essential constituent, improves the treatment characteristics of air pollutants.

That is, the present invention based on the above findings is
Manganese dioxide and / or hydrogenated manganese oxide having a spinel type crystal structure contains, in addition to manganese and oxygen, a metal other than manganese as an essential constituent component, and has an oxidation number of +3 and / or +4. An air pollutant treatment agent characterized by containing as an active ingredient a spinel-type metal-manganese composite oxide obtained by removing or exchanging some or all of metal ions with hydrogen ions. . The metal is lithium,
Use magnesium or iron. In addition, this treatment agent,
It can be applied to a gas to be treated containing at least one of sulfur oxide, nitrogen oxide and oxidants.

[0013]

The structure and operation of the present invention will be described. A typical composite manganese oxide having a spinel type crystal structure according to the present invention is a compound containing lithium, in which manganese having a valence of +3.5 (oxidation numbers of +3 and +4 are mixed in equal amounts). There is LiMn ₂ O ₄ and +4 valence Li _1.33 Mn _1.67 O ₄ .

These are obtained, for example, by firing a powder mixture of manganese carbonate and lithium carbonate at several hundreds of degrees Celsius, and by adjusting the mixing ratio of both carbonates, both composite oxides are solidified in various proportions. A dissolved oxide is obtained. LiMn ₂ O ₄ can replace up to 1/6 of the Mn site of the crystal lattice with Li, and as a result, the oxidation number of manganese gradually increases to +4. That is, as the average oxidation number of manganese exceeds +3.5, LiMn ₂ O ₄
Li _1.33 Mn _1.67 O ₄ is considered to be gradually generated.

Both oxides dissolve out lithium by acid treatment
Can be done, but the behavior is different. LiMn
₂O_FourContains manganese, which is soluble in acid and has an oxidation number of +3.
It causes a homogenization reaction, and part of it becomes +2 valent manganese ion.
Eluate and the rest is non-soluble +4 valent spine
It becomes manganese dioxide with a le structure. +4 valent manganese only
Consisting of Li_1.33Mn_1.67O_FourSo there is no dissolution of manganese,
Lithium ions become hydrogen ions while maintaining the pinel structure
Replace sequentially. Therefore, Li_(1.33-X)H _XMn_1.67O
_Four (X: 0-1.33) is a general chemical formula.

Even with metals other than lithium, +3 valence and /
Alternatively, a spinel-type metal-manganese composite oxide containing +4 valent manganese ions is prepared. For example, magnesium and iron have an oxidation number of +3, such as MgMn ₂ O ₄ and FeMn ₂ O _4.
Since compounds such as ₂ MnO ₄ containing manganese ions with an oxidation number of +4 are produced, they react with acids in the same manner as described above.

The present inventors have, since it is often the manganese oxide exhibits a high reactivity to oxidation or the like, the adsorption with respect to nitrogen monoxide and examining the reactivity of the spinel structure H _{1 .33} Mn _1.67 O ₄ shows excellent performance, and Li _(1.33-X) H _X Mn _1.67 O ₄ with unsubstituted lithium ions left
(X: 0-1.33) is relatively inferior to the completely substituted product, but has been found to be superior to conventional manganese oxides, and has come to propose JP-A-5-253474. Further investigated this proposal and confirmed that more spinel-type manganese oxide could be used in the removal or removal of more air pollutant components in pretreatment reactions.

The various kinds of spinel type manganese oxides are
Spinel type complex oxide containing +3 valent manganese ion XM
Manganese dioxide, commonly referred to as λ-MnO ₂ , synthesized by acid treatment of n ₂ O ₄ (X: Li, Mg, Fe, etc.) with elution of some or all of the ions of metal X, and +4 Spinel-type composite oxide containing highly valent manganese ions Li _1.33 Mn _1.67 O ₄
It is at least one kind of compound synthesized by acid treatment of XMn ₂ O ₄ (X: Mg, etc.), in which some or all of metal ions are exchanged with hydrogen ions. The metal forming the complex oxide is not limited to these, but it is advantageous because the manganese oxide can be easily produced by using the above-mentioned metal as a raw material and there are few problems such as cost and post-treatment.

It was confirmed by experiments including comparison with conventional agents that these compounds are excellent as treating agents for sulfur oxides, nitrogen oxides and oxidants (using ozone as a typical component).

[0020]

EXAMPLES Examples of the present invention will be described, but the present invention is not limited thereto. Example 1 Manganese carbonate, powders of metal carbonates constituting the composite manganese oxide were mixed at a predetermined ratio, and the spinel-type composite manganese oxide synthesized by heating and sintering was treated with hydrochloric acid to obtain various manganese. Oxides were synthesized and molded into a diameter of 2-3 mm. The spinel-type composite manganese oxides (starting substances) synthesized by heating and sintering at this time and various manganese oxides after hydrochloric acid treatment (main producing substances) are shown below.

No. Starting material Main product (1) LiMn ₂ O ₄ λ-MnO ₂ (Li residual ratio: 0.64) (2) LiMn ₂ O ₄ λ-MnO ₂ (Li residual ratio: 0.11) (3 ) MgMn ₂ O ₄ λ−MnO ₂ (Mg residual ratio: 0.47) (4) MgMn ₂ O ₄ λ−MnO ₂ (Mg residual ratio: 0.08) (5) FeMn ₂ O ₄ λ−MnO ₂ (Fe Residual rate: 0.52) (6) Li _1.33 Mn _1.67 O ₄ Li _(1.33-X) H _X Mn _1.67 O ₄ X = 0.30 (Li residual rate: 0.77) (7) Li _1.33 Mn _1.67 O ₄ Li _{(1.33- X)} H _X Mn _1.67 O ₄ X = 0.74 (Li residual ratio: 0.44) (8) Li _1.33 Mn _1.67 O ₄ Li _(1.33-X) H _X Mn _1.67 O ₄ X = 1.20 (Li residual ratio: 0.10 ) (9) Mg ₂ MnO ₄ Mg _{(1.33-X) / 2} H _X Mn _1.67 O ₄ X = 0.79 (Mg residual ratio: 0.41)

Further, as a comparative example, (10) Manga dioxide commercially available
(Merck) and (11) iron-manganese composite oxide (iron
40 mass%, manganese 22 mass%, manufactured by Nissan Gardler),
In addition, it is a spinel type complex oxide before acid treatment (12)
LiMn₂O_FourAnd (13) Li_1.33Mn _1.67O_FourThe same grain size
I used it.

In the experiment, about 5 ppmv of nitrogen oxides (95-97% of which is nitric oxide, the balance being dioxide) was placed in a 2.2 cm diameter cylindrical container filled with each of the above granules at a height of 10 cm. Nitrogen), about 5ppmv of SO ₂ , or about 5ppmv of ozone is added to the air, and the flow rate is 5.0Nl / min and the temperature is 25 ℃ or
It was supplied at 40 ° C. and a humidity of 30% or 60%, and the outlet concentration was analyzed. Table 1 shows the average throughput of about 6 hours after the start of treatment.

[0024]

[Table 1]

As shown in Table 1, the treatment agents (1) to (1) of the present invention
The performance of (9) did not change much in this time. Ozone and sulfur dioxide are removed with high efficiency,
Most of the nitric oxide was converted to nitrogen dioxide, which was easily removed by an adsorbent such as activated carbon, or was adsorbed on the oxide, and the release as nitric oxide was slight.

Although the treatment performance is greatly improved by acid-treating the metal ions constituting the complex oxide, λ-Mn
It was found that there was no great difference between the O ₂ type and the hydrogen ion substitution type, that the treatment capacity improved as the residual ratio of metal ions decreased, and that the difference due to the metal ion species was also small.

Example 2 Next, the treating agents of (2), (4), (8) and (10) were filled in the same amount as in Example 1 and nitrogen oxides at a temperature of 40 ° C. and a humidity of 30% were used. 5ppmv
Air containing or containing 5 ppmv of ozone was supplied at a flow rate of 20 Nl / min, and as shown in Table 2, day 0, day 7, day 20, 43
On the day, the flow rate was lowered to 5.0 Nl / min for 3 to 4 hours, and the change in processing performance with time was measured. The measured value was an average value for 3 to 4 hours. The results are shown in Table 2.

[0028]

[Table 2]

As shown in Table 2, each treating agent of the present invention is
It can be seen that the durability is far superior to the comparative example as well as the initial performance.

[0030]

Since the present invention is constructed as described above, it adsorbs (or decomposes), removes and removes sulfur dioxide, nitrogen oxides, and oxidants that are pollutants contained in the atmosphere. Since it can be released after being oxidized to a compound that can be easily removed in the step (2), this property can be utilized for environmental purification and is extremely useful industrially.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B01D 53/50 53/81 53/56 53/86 ZAB 53/94 B01J 20/04 ZAB C 23 / 34 ZAB A B01D 53/34 123 A 129 A 53/36 ZAB D ZAB F 102 G

Claims (4)

[Claims] 1. A manganese dioxide having a spinel type crystal structure,
Alternatively, an agent for treating air pollutants, which contains, as an active ingredient, at least one of spinel-type hydrogenated manganese oxide, which contains hydrogen as an essential constituent in addition to manganese and oxygen. 2. The manganese dioxide and / or hydrogenated manganese oxide having a spinel type crystal structure contains, in addition to manganese and oxygen, a metal other than manganese as an essential constituent component, and has an oxidation number of manganese of +3 and / Or +
4. The agent for treating air pollutants according to claim 1, which is obtained by removing or exchanging a part or all of metal ions of the spinel-type metal-manganese composite oxide of 4 above. 3. The agent for treating air pollutants according to claim 2, wherein the metal is lithium, magnesium or iron. 4. The agent for treating air pollutants according to claim 1, 2 or 3, wherein the air pollutants contain at least one of sulfur oxide, nitrogen oxide and oxidants.