KR102054289B1 - Filter impregnated alkali metal compound for removing NO2 and air purifier including thereof - Google Patents

Abstract

The present invention relates to a filter having an excellent removal performance of nitrogen dioxide used in an air purifier, etc., wherein an alkaline substance of alkali metal hydroxide or carbonate is impregnated on the surface of activated carbon, and activated carbon impregnated with the alkaline substance is loaded on the filter member. It provides an air purifier comprising a filter for removing nitrogen dioxide adsorption and the filter for removing nitrogen dioxide adsorption.

Description

Filter impregnated alkali metal compound for removing NO2 and air purifier including others}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter having a specific function used in an air purifier and the like, and more particularly to a filter excellent in removing nitrogen dioxide used in an air purifier such as an air purifier.

Flue gases released after combustion contain nitrogen dioxide, which increases the incidence of acute respiratory disease and severely stimulates respiratory stimulation, bronchitis, and mucous membranes. Accordingly, the World Health Organization (WHO) regulates the average annual pollution level of nitrogen dioxide to 40 µg / m 3 for public health.

In addition, such nitrogen dioxide is one of the causes of acid rain and air pollution, and many environmental regulations are trying to reduce the emissions by treating such nitrogen dioxide before it is discharged to the environment. However, such nitrogen dioxide in the atmosphere is increasing gradually, especially in urban areas.

Therefore, there is a need for a treatment method for treating nitrogen dioxide before such nitrogen dioxide is discharged to the environment. Regarding the removal of nitrogen dioxide, many studies have been reported, for example, using various adsorbents such as activated carbon fibers or zeolites, and removing nitrogen dioxide by selective catalytic reduction in the presence of NH ₃ . have. In addition, as an efficient method for removing nitrogen dioxide, adsorption with activated carbon has also been studied and applied.

The present invention seeks to provide a filter optimized for the removal of nitrogen dioxide present in the combustion flue gas or the atmosphere and an air purifier applying the filter.

The present invention is a filter for removing nitrogen dioxide present in the air, an alkaline substance of alkali metal hydroxide or carbonate is impregnated on the surface of the activated carbon, the activated carbon impregnated with the alkaline substance for adsorption and removal of nitrogen dioxide loaded on the filter member Provide a filter.

The alkaline substance is preferably impregnated in the range of 2.5 to 10 parts by weight based on 100 parts by weight of activated carbon.

The alkali metal may be selected from the group consisting of Na, K, Li, and Rb, and more preferably Na or K. Most preferably the alkaline material may be K ₂ CO ₃ .

Further, the filter member may be a nonwoven fabric or a honeycomb structure.

When the filter member is a nonwoven fabric, the activated carbon impregnated with the alkaline material may include 0.5 to 2% by weight of the total weight of the filter.

In addition, when the filter member is a honeycomb structure, activated carbon is filled in the honeycomb structure, and activated carbon impregnated with the alkaline substance may be added at least 15% by weight of the total activated carbon.

In addition, the present invention provides an air purifier comprising the filter for removing nitrogen dioxide adsorption as described above.

By applying the filter of the present invention to an air purifier such as an air purifier together with an existing deodorizing filter, it is possible to effectively remove odorous substances and nitrogen dioxide present in the atmosphere.

Furthermore, the filter of the present invention can remove nitrogen dioxide without generating nitrogen monoxide in the process of removing nitrogen dioxide.

1 is a view conceptually showing a reaction mechanism in which the filter of the present invention adsorbs and removes nitrogen dioxide.
Figure 2 is a graph showing the concentration of NOx contained in the air according to Example 1 with time.

Adsorption with activated carbon has been applied to efficiently remove nitrogen dioxide. Such activated carbon is a carbonaceous material having a fine porous structure, and its surface is nonpolar. Therefore, the adsorption capacity of activated carbon is due to van der Waals' force, and nitrogen dioxide is adsorbed onto the activated carbon by a physical mechanism.

Therefore, activated carbon generally exhibits low performance for adsorption of low boiling components such as carbon monoxide and ammonia. However, when chemical substances are attached to such activated carbon, chemical adsorption by chemicals adhering to the surface of activated carbon can be simultaneously obtained along with physical adsorption by fine pores of activated carbon, thereby effectively adsorbing and removing nitrogen dioxide present in the air. After confirming that the present invention has been completed.

Hereinafter, the present invention will be described in more detail.

Suitable filters for removing nitrogen dioxide of the present invention are filters comprising activated carbon impregnated with alkali metals.

The activated carbon used in the present invention is not particularly limited, and generally used and commercially available activated carbon can be suitably used in the present invention. For example, those produced from raw materials such as wood, lignite, anthracite and palm husk can be used.

Further, the particle size, pore size, pore volume, etc. of activated carbon for use in the filter of the present invention is not particularly limited in the present invention, and may be suitably used in the present invention as long as it is in the range normally used for filter production.

By using such activated carbon, nitrogen dioxide can be removed by physically adsorbing nitrogen oxide in the air to pores present in the activated carbon.

However, such physical adsorption of activated carbon alone is insufficient to obtain a sufficient removal effect of nitrogen dioxide.

Also, in general, NO ₂ in a state where water coexists, that is, in air, reacts as shown in the following formula (1).

3NO ₂ + H ₂ O → 2HNO ₃ + NO (1)

That is, 1 mole of NO is produced from 3 moles of NO ₂ by the reaction of NO ₂ with water vapor.

Subsequently, with respect to activated carbon, NO ₂ is oxidized by reaction with nitric acid produced by the reaction of formula (1), as shown in formula (2), together with the reaction as in formula (1) above. (Normally NO ₂ ) is produced.

C (activated carbon) + 4HNO ₃ → CO ₂ + 4NO ₂ + 2H ₂ O (2)

NO ₂ produced in the above formula (2) is converted into NO by reaction of water and the formula (1) again. Therefore, even though the physical adsorption by activated carbon alone can remove the NO ₂ , there is a problem in that NO is newly generated. Therefore, there is a need for a NOx removal filter capable of suppressing the generation of NO as well as the removal of NO ₂ .

Therefore, if the chemical adsorption can be achieved along with the physical adsorption by the fine pores on the surface of the activated carbon, it can bring a significant synergistic effect of the adsorption capacity. Therefore, by adhering a chemical substance capable of chemically reacting with nitrogen dioxide on the surface of activated carbon, not only can the chemical adsorption of nitrogen dioxide be achieved, but also the production of NO can be suppressed.

Alkali metal compounds, such as Na, K, Li, and Rb, may be used as the chemicals deposited on the surface of activated carbon. Suitable alkali metal compounds in the present invention include hydroxides, carbonates and the like of alkali metals.

Such an alkali metal compound reacts with nitrogen dioxide with moisture present in the atmosphere to produce nitric acid, and the nitric acid can chemically adsorb and remove nitrogen dioxide by reacting with the alkali metal compound.

When the alkali metal compound according to the present invention is attached to the surface of the activated carbon, a neutralization reaction such as NO ₂ and formula (3) occurs.

2NaOH + 2NO ₂ → NaNO ₃ + NaNO ₂ + H ₂ O (3)

That is, NO ₂ neutralizes an alkali metal compound such as NaOH, and generates a chemically stable neutralized salt such as nitrate or nitrite by the neutralization reaction. This concept is schematically illustrated in FIG. 1.

Therefore, it is more preferable to use the alkali metal compound containing potassium or sodium which is excellent in the reactivity which can react with nitrogen oxide and form nitrate among these alkali metals. By coating such alkali metal compounds in the pores of activated carbon, nitric acid or nitrite produced by the neutralization reaction of alkaline substances and NO ₂ can be fixed to the pores of activated carbon, thereby efficiently removing nitrogen oxides in the exhaust gas. Of course, the generation of NO can also be prevented.

In order to remove the adsorbed NO ₂ is more preferable to select a material which is stable without the possibility ignition or explosion due to the internal pore of activated carbon while using a neutralization reaction pressure and temperature. In the case of KOH, in the deposition on activated carbon, there may be a problem of ignition or explosion possibility due to pressure, temperature, etc. inside the pore of activated carbon, and from the viewpoint of stability, using potassium carbonate which can be used stably at room temperature and atmospheric pressure conditions Most preferred.

A reaction formula for adsorbing and removing NO ₂ by coating potassium carbonate inside the pores of activated carbon can be expressed as in Equation (4).

2NO ₂ + K ₂ CO ₃ → KNO ₂ + KNO ₃ + CO ₂ (4)

The content of the alkali metal compound impregnated on the surface of the activated carbon may vary depending on the type of alkali metal to be impregnated, but it is most appropriate to apply 4-6 parts by weight of the alkali metal compound with respect to 100 weight of the activated carbon. However, this can be said to vary depending on the specific surface area of the activated carbon, and even if the alkali metal compound deposition rate is increased, the effect does not increase indefinitely depending on the loading method and the use conditions. It may be used in an amount of 2.5 to 10 parts by weight, more preferably 3 to 7 parts by weight, based on the weight parts.

If the alkali metal compound is impregnated below the above range, the effect of improving the chemical adsorption capacity of nitrogen dioxide by the impregnation of the alkali metal compound is not sufficiently obtained, and if the alkali metal hydroxide is impregnated above the above range, the pores on the surface of the activated carbon are Occlusion results in a decrease in the physical adsorption capacity of the activated carbon by the pores, thereby reducing the overall amount of nitrogen dioxide adsorption.

Although the method of depositing such an alkali metal compound on the surface of activated carbon is not specifically limited, It can be obtained by immersing activated carbon in the aqueous solution of the said alkali metal compound. In adhering the alkali metal compound to the surface of activated carbon, it is more preferable to carry out under vacuum. Immersion time is not particularly limited, but may be performed, for example, for 1 to 7 hours or 2 to 5 hours. Further, after the immersion step, activated carbon may be washed with deionized water and then dried to obtain activated carbon impregnated with an alkali metal hydroxide.

The nitrogen dioxide adsorption removal filter of this invention is obtained by loading the activated carbon on which the above-mentioned alkali metal compound was stuck on a general filter member. In this case, the filter member is not particularly limited as long as it is suitably used in forming a filter, and examples thereof include a nonwoven fabric and a honeycomb structure.

When a nonwoven fabric is used as the filter member, for example, a filter may be formed by attaching an alkali metal compound to the surface of the activated carbon and then coating the nonwoven fabric, and further, after the activated carbon is coated on the nonwoven fabric, the alkali metal compound May be deposited on the surface of activated carbon.

In addition, by applying the activated carbon impregnated with the alkali metal compound according to the present invention to the honeycomb-type structure as the filter member, it is possible to form a filter for removing nitrogen dioxide.

Activated carbon impregnated with an alkali metal compound loaded on the surface of the filter member is intended to neutralize and remove nitrogen oxides, and in order to implement a universal removal effect on gaseous substances other than nitrogen oxides as a whole, the alkali metal compound In addition to the impregnated activated carbon, other components, for example, metals such as Cu and Mn, and impregnated activated carbon to which a phosphate-based compound is impregnated can be used. In this case, the capacity of the alkali-impregnated activated carbon according to the expected performance of the filter can be determined, and the alkali metal compound-impregnated activated carbon loaded on the filter is preferably loaded in a range of 20-30% by weight of the total activated carbon for an appropriate effect. .

Since the alkali metal compound-impregnated activated carbon of the present invention is loaded within the above range, sufficient nitrogen oxide removal efficiency can be obtained, so that side effects of reducing the removal effect of other gas components are reduced rather than increasing the additional NOx removal efficiency due to exceeding the above range. Can be larger. However, if the purpose is to remove only nitrogen oxide, it is also possible to use 100% of the activated carbon impregnated with the alkaline component according to the present invention.

The alkali metal compound-impregnated activated carbon according to the present invention may be coated on a nonwoven fabric to prepare a filter. In this case, the coating or loading amount of the activated carbon may be appropriately adjusted according to the desired filter performance, but is not particularly limited. It may be about 1% of, for example, 0.5 to 2% by weight. In the case where the filter member is a nonwoven fabric, it is more preferable to use activated carbon of fine granule type for coating on the filter member.

In addition, the filter member may be mounted on a honeycomb structured body. At this time, in the honeycomb structure, the alkaline component-impregnated activated carbon of the present invention may be mixed with the metal such as Cu and Mn or the impregnated activated carbon to which a phosphate-based compound is impregnated, as described above, according to the performance required for the filter. have. In this case, the alkaline component impregnated activated carbon according to the present invention can be used in the range of 15% by weight or more, preferably 15 to 30% by weight of the total weight of the activated carbon. When the alkali component-impregnated activated carbon content is less than 15% by weight, the effect of removing nitrogen oxides may be lowered, and when it exceeds 30% by weight, the removal effect of other gaseous components to be removed may be reduced.

However, in the case where the main purpose is to remove nitrogen oxides, the upper limit thereof is not particularly limited, and only the alkali component-impregnated activated carbon can be filled and used in the honeycomb structure.

By applying the filter thus obtained to an air purifier together with the existing deodorizing filter, it is possible to effectively remove nitrogen dioxide present in the air. The air purifier is not particularly limited as long as it is used to remove harmful components or factors causing unpleasantness from a gas stream such as air or exhaust gas. For example, an air purifier, an automobile air filter, and a gas range hood. And the like, and may be applied to the filters of these air cleaners.

Example

Hereinafter, an Example is given and this invention is demonstrated more concretely. The following examples relate to one embodiment of the present invention, which is not intended to limit the present invention.

Example  One

The granule-type activated carbon having a BET specific surface area of 1050 to 1150 m ² / g was immersed in an aqueous solution of potassium carbonate (K ₂ CO ₃ ) under vacuum and then left for 3 hours to firstly impregnate potassium carbonate into pores of activated carbon. Thereafter, after the drying for a predetermined time, secondary impregnation was performed in the same manner to obtain impregnated activated carbon containing 5% by weight of potassium carbonate based on the total weight of the impregnated activated carbon.

Activated carbon impregnated with potassium carbonate in a vacuum atmosphere was surface coated at a level of about 0.3 g at a rate of 1% by weight per 1 m ² of a nonwoven fabric to obtain a filter.

The obtained NOx removal filter was applied to an air cleaner to evaluate the NOx removal efficiency. To evaluate the NOx removal efficiency, 10 ppm of NO ₂ was supplied into an 8 m ³ volume chamber equipped with an air cleaner (flow fan), and the air cleaner was operated. The NOx content in the chamber was measured and evaluated for 30 minutes in increments of 5 minutes.

As a result of the evaluation, NO ₂ was completely removed from the chamber after about 5 minutes, and NO was not measured.

Example  2

An impregnated activated carbon in which potassium carbonate was impregnated in the activated carbon pores was obtained in the same manner as in Example 1 except that a particle diameter of 3 φ granular type activated carbon was used.

The obtained potassium carbonate impregnated activated carbon was loaded in a honeycomb frame, and the activated phosphate-impregnated activated carbon and the impregnated activated carbon were filled together. Each filled amount of activated carbon was filled with 80g of potassium carbonate-impregnated activated carbon, 110g of phosphate-impregnated activated carbon and 110g of impregnated activated carbon with respect to 300g of the total amount of activated carbon.

The obtained NOx removal filter was applied to an air cleaner to evaluate the NOx removal efficiency. To evaluate the NOx removal efficiency, 10 ppm of NO ₂ was supplied into an 8 m ³ volume chamber equipped with an air cleaner (flow fan), and the air cleaner was operated. The NOx content in the chamber was measured and evaluated for 30 minutes in increments of 5 minutes.

The evaluation results are shown in Table 1 below, and the change in NOx concentration according to time change is also shown in FIG. 2.

Early 5 minutes 10 minutes 15 minutes 20 minutes 25 minutes 30 minutes % Removal NO ₂ 10 0 0 0 0 0 0 100 NO 0 0 0 0 0 0 0 -

From Table 1, it can be seen that NO ₂ contained in the air can be completely removed within a quick time of 5 minutes or less, and there is no generation of NO due to reaction with activated carbon even after a long time.

Example  3 and Comparative example  1 to 3

The impregnated activated carbon was prepared in the same manner as in Example 2, except that the components shown in Table 2 were each impregnated on the surface of the activated carbon, and the honeycomb structure was filled with 300 g in a weight ratio of 1: 1 with no impregnated activated carbon. It was.

The obtained NOx removal filter was applied to an air cleaner to evaluate the NOx removal efficiency. NOx removal efficiency of the evaluation is NO ₂ NO 10ppm 10ppm and was supplied into the driving chamber of the 8m ³ volume equipped with the air cleaner (Flow Fan), and the air cleaner. The NOx content in the chamber was measured and evaluated for 30 minutes in increments of 5 minutes, and the results are shown in Table 2 below.

Impregnated Ingredients Time (min) 0 5 10 20 30 NO ₂ removal rate
(%) Example 3 K ₂ CO ^- ₃ 0 55 77 100 100 Comparative Example 1 phosphate 0 65 82 95 100 Comparative Example 2 CuCl ₂ 0 43 64 82 89 Comparative Example 3 Mn (II) Cl ₂ 0 58 75 92 100 NO removal rate
(%) Example 3 K _-2 O 0 25 50 50 75 Comparative Example 1 phosphate 0 -25 -75 -45 -65 Comparative Example 2 CuCl ₂ 0 -20 -80 -100 -120 Comparative Example 3 Mn (II) Cl ₂ 0 -50 -50 -50 -50

As can be seen from Table 2, in the impregnated activated carbon of Comparative Examples 1 to 3, the effect of removing nitrogen dioxide gradually increased over time was similar to Example 3, but NO was generated on the contrary. And it was found.

On the other hand, it can be seen that the activated carbon of Example 3 to which potassium carbonate is impregnated does not increase the concentration of NO but rather removes only 10 ppm of NO injected into the chamber.

Claims (9)

Alkali substance of alkali metal hydroxide or carbonate is impregnated on the surface of activated carbon, activated carbon impregnated with the alkaline substance is loaded on the nonwoven filter member, and activated carbon impregnated with the alkaline substance is 0.5 to 2 weight of the total weight of the filter. Nitrogen dioxide adsorption removal filter containing%.
Alkali metal hydroxide or carbonate alkaline material is deposited on the surface of the activated carbon, activated carbon is filled in the honeycomb structure, and activated carbon impregnated with the alkaline material is at least 15% by weight of the total weight of activated carbon filled in the honeycomb structure. Adsorption removal filter.
The filter of claim 1 or 2, wherein the alkaline material is impregnated in a range of 2.5 to 10 parts by weight based on 100 parts by weight of activated carbon.
The filter for removing nitrogen dioxide adsorption according to claim 1 or 2, wherein the alkali metal is an alkali metal selected from the group consisting of Na, K, Li and Rb.
The filter for nitrogen dioxide adsorption removal according to claim 1 or 2, wherein the alkali metal is Na or K.
The filter for nitrogen dioxide adsorption removal according to claim 1 or 2, wherein the alkaline substance is K ₂ CO ₃ .
delete delete Air purifier comprising the nitrogen dioxide adsorption filter of claim 1 or 2.

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