JP2002126451A - Device for removing nitrogen oxides in air - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device suitable for removing NOX in the air, particularly discharged from (1) a tunnel, (2) a underground car park, (3) a vehicle for construction and work (grouped minor fixed generation source) and used continuously at low cost. SOLUTION: In the device for removing nitrogen oxides in the air, air is passed through a narrow gap between a pair of parallel plates, the nitrogen oxides in the air are diffused on the inside surface of the parallel plates during the air is passed and are adsorbed on the inside surface provided with a coating layer composed of a titanium oxide superfine particle photocatalyst and a hydroxyl apatite fine particle adsorbent. The titanium oxide superfine particle photocatalyst is a superfine particle having <=10 nm average particle diameter, the hydroxyl apatite fine particle adsorbent has <=5 μm average particle diameter and the ratio by weight of the titanium oxide superfine particle photocatalyst to the hydroxyl apatite fine particle adsorbent is preferably 2:1 to 1:2. The removing device is preferably used to be installed in an air flow passage of an air conditioner or a gas flow passage of exhaust gas treating equipment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention provides apparatus for removing nitrogen oxides in the atmosphere (NO _X), in particular, for use in annexed to the gas flow path of the air passage or the exhaust gas treatment apparatus of the air conditioner The present invention relates to a suitable nitrogen oxide removal treatment apparatus by a diffusion scrubber method.

[0002]

2. Description of the Related Art Technology for removing nitrogen oxides from the atmosphere is mainly developed for factories, automobiles, and other sources of emission, and said to be several thousand ppm emitted from large-scale factories. Regarding high-concentration nitrogen oxides, the "selective catalytic reduction method" in which nitrogen oxides are reduced to water by reaction with ammonia has been put to practical use. In addition, the emission of nitrogen oxides from gasoline engine vehicles has been improved by introducing "three-way catalysts", "lean burns" and the like.

[0003] There is also known a technique for purifying nitrogen oxides in the atmosphere using sunlight using a titanium oxide photocatalyst.
Applying titanium oxide to paved roads and road structures,
Recently, the purification performance has been confirmed along the roads of local governments, and its purification performance has been confirmed (Hiroshi Takeuchi, "Purification and Restoration Technology of Environmental Air by Photocatalyst", Journal of the Japan Society for Atmospheric Environment, 33, 139-1).
50, 1998). In addition, an example in which titanium oxide is used for exhaust equipment of a road tunnel has been reported (Satoshi Nishikata, “Low-concentration denitration equipment”, Industrial Materials, 45, 86-88, 199).
7 years).

Other means for removing nitrogen oxides in the atmosphere using a titanium oxide photocatalyst include "ventilation equipment for automobile tunnels" (JP-A-5-237381) and "method for removing pollutants and purification material". (JP-A-6-315614
JP-A-8-15), "Tunnel air purification device" (JP-A-8-15)
No. 1899), “Air purification device in tunnel and tunnel interior plate used in the device” (JP-A-9-27)
No. 1635), “A method for purifying contaminated air on expressways” (JP-A-10-151323), “Gas purification / sound absorbing member, gas purification device and gas purification system” (JP-A-10-249167). Etc. are known.

It is also known that when nitrogen oxides in a gas are adsorbed by titanium oxide fine particles, the adsorbing efficiency can be increased by mixing hydroxyapatite powder with the titanium oxide fine particles (Y. Komazaki et al.).
l., Atoms. Environ., 33, 4363-4371, (1999)).

[0006]

With the increasing public interest in air pollution, various air purifying technologies have been studied. However, compared to the importance of the problem, many of the technologies are merely diversions of the existing filtering method and the removal technology using an adsorbent such as activated carbon, and there are doubts regarding the processing capacity and the throughput. There are many things that have to be done.

In tunnels, underground roads, underground parking lots, etc.,
Is discharged from the individual car sources of, removal of the NO _X in the relatively low concentration diluted in air (number ppm) becomes the target, "selective catalytic reduction method" is not theoretically effective removal countermeasure technology in addition, since the processing facilities and equipment and operating costs will be enormous, not used as nO _X removal technique.

Recently, an air cleaning technology using a titanium oxide photocatalyst has also been developed. This technique does not require special equipment, albeit an economical purification techniques NO _X,
Because it is a batch-type contaminated air treatment technology in a reaction tank,
The amount of contaminated air treatment is as small as several liters per minute, which is a problem for treating a large amount of contaminated air. Moreover, the effect of removing the coating titanium oxide surface as is, it is basically difficult to remove NO _X diffused in a wide space efficiently.

Therefore, it is necessary to develop not only an extension of the conventional technology but also an innovative air cleaning technology capable of efficiently and completely removing harmful gas components and treating a large amount of contaminated air. The present invention, NO _X in the atmosphere has become a long-standing problem in metropolitan areas around the world including the Japanese, in particular,
Development tunnel, underground parking, less energy consumption in a suitable low-cost to remove NO _X discharged in construction and construction vehicles (Gunsho stationary sources), a circular efficient device that can be used continuously The task is to

[0010]

The present inventors first blended a binder with a titanium oxide (TiO ₂ ) fine particle photocatalyst and hydroxyapatite (HAP) powder, and formed a film on the inner wall surface of a glass tube. Fixing the gap between the outer glass tube and the inner quartz tube as a gas flow path for sampling, and providing a means for irradiating the inner wall surface of the glass pipe of the gas flow path with ultraviolet light, so that NO in the gas is provided. and the _X adsorbed on the inner wall surface of the glass tube, has been developed suction tube to measure the concentration of the NO _X in the gas from the adsorption amount (JP-a-8-94502). But,
The suction tube is measured simply by adsorbing NO _X in the gas, a tube for analysis, was not a device that can solve the above problems.

The present inventors have developed a titanium oxide ultrafine particle photocatalyst.
High NO using_XContinuously usable nitrogen with removal efficiency
As a result of continuing research and development on oxide removal equipment,
Nitrogen oxides in the air are removed by the removal device using the Clava method
It has been found that it can be efficiently removed. Also, this device
The oxidation applied to the inner wall surface of the parallel plate at a specific rate.
Ultrafine titanium photocatalyst and hydroxyapatite fine particles
Adsorbent (hereinafter referred to as “TiO _Two/ HAP ")
Contaminated sky with high removal efficiency continuously over a long period of time
NO in the air_XCan be removed.

That is, according to the present invention, air flows in a narrow gap between a pair of parallel plates, and nitrogen oxides in the air are diffused on the inner wall surface of the parallel plates while flowing through the parallel plates. An apparatus for removing nitrogen oxides in the air, wherein the apparatus is adsorbed and removed on an inner wall surface provided with a coating layer made of a hydroxyapatite fine particle adsorbent.

Further, according to the present invention, the specifications of the removal processing apparatus are as follows:
The above apparatus for removing nitrogen oxides from the atmosphere, wherein the inner wall surface of the parallel plate is set by Gormley-Kennedy's theoretical formula assuming that it is an ideal perfect adsorption surface of nitrogen oxides. .

Further, the present invention is characterized in that a coating layer comprising a titanium oxide ultrafine particle photocatalyst and a hydroxyapatite fine particle adsorbent is provided on the inner wall surfaces of a pair of parallel plates to realize a complete adsorption surface of nitrogen oxides. An apparatus for removing nitrogen oxides in the atmosphere described above.

Further, according to the present invention, the titanium oxide ultrafine particle photocatalyst is an ultrafine particle having an average particle diameter of 10 nm or less, the hydroxyapatite fine particle adsorbent is an average particle diameter of 5 μm or less, The above apparatus for removing nitrogen oxides from the atmosphere, wherein the weight ratio of the hydroxyapatite fine particles is 2: 1 to 1: 2.

Further, the present invention is the above-mentioned apparatus for removing nitrogen oxides from the atmosphere, which is used by being attached to an air flow path of an air conditioner or a gas flow path of an exhaust gas processing apparatus.

The diffusion scrubber method used in the present invention means that (1) gas is diffused to the inner wall surface of the parallel plate, and (2) gas reaching the inner wall surface is adsorbed and removed on the inner wall surface.
This is a method of collecting and removing gas using diffusion, and is a method of selectively removing gas by utilizing the fact that the diffusion coefficients of gas and particles are significantly different. FIG. 7 schematically shows the diffusion scrubber method. In this diffusion scrubber method, the removal efficiency of gas components in the atmosphere is determined by the following Gormley-Kenned:
y Theoretical formula (PG Gormley, M. Kennedy, Proceedings of the
Royal Irish Academy, Vol. 52A, 163-169, (1949)). f = 1- [0.910 exp (-3.77 .mu.) + 0.0
531 exp (−42.8 μ)], μ = bDL / aQ In the above equation, f: removal efficiency, D: diffusion coefficient of the target gas (cm ² / sec, a: interval between parallel plates,
L: length (cm) of parallel plate, μ: deposition parameter, Q:
Atmospheric suction flow rate (cm ³ / sec), b: width of parallel plate (cm)
It is.

The present invention, decomposing the hydroxyapatite particles of titanium oxide ultrafine particles photocatalyst and a gas adsorbent NO _X, was used to adsorb an "optical denitration method" is the method of removing harmful gas components by a simple apparatus Conventional “diffusion scrubber method”
By combining a particular condition the door, without concentration the NO _X in low concentrations in the atmosphere directly, there is provided a means for removing and processing continuously for a long period of time.

The removal treatment apparatus of the present invention provides a flat coated layer of a titanium oxide ultrafine particle photocatalyst and a hydroxyapatite fine particle of a gas adsorbent on the inner wall surface of a parallel plate having a flat surface. Is removed on the coating surface of the inner wall of the parallel plate. Since air flows through the gap between the parallel plates, the airflow resistance is extremely low unlike a filtering method such as a filter.

In the "photo-denitrification method" using a titanium oxide ultrafine particle photocatalyst and a hydroxyapatite fine particle as a gas adsorbent, NO _x is chemically changed into NO ₂ or HNO ₃ and this is washed away with water. A stainless steel plate having high corrosion resistance is suitable because it is used under extremely corrosive conditions. In addition, a stainless steel plate has TiO ₂ and H
It shows excellent adhesiveness only by mixing AP in a binder such as polytetrafluoroethylene and an organic solvent such as acetone and then coating and drying, and has no problem in strength and durability in long-term use

The size of the parallel plate can be appropriately determined according to the scale of the apparatus. For example, as shown in FIG.
Air flow path surface is 10 × 0.5cm (Ventilation cross section 5c)
m ² ), make a basic unit with a flow path length of about 35 cm,
Such units may be stacked and combined according to the scale of the apparatus and used.

The gap between the parallel plates is determined by Gormley-K in the diffusion scrubber method schematically shown in FIG. 7 on the assumption that the inner wall surface of the parallel plate is an ideal perfect adsorption surface for nitrogen oxides.
It can be set according to the equation of endy. In the case of the above basic unit, nearly 100% of nitrogen oxides can be removed by setting the interval between the parallel plates of about 0.5 cm under the condition of a ventilation flow rate of 10 liter / min (wind velocity of 0.33 m / sec).

With regard to the combination of the titanium oxide ultrafine particle photocatalyst and the hydroxyapatite fine particle applied to the surface of the parallel plate, the smaller the particle size of the titanium oxide ultrafine particle photocatalyst is, the larger the surface area becomes, which is advantageous for removing nitrogen oxides. Act on. Therefore, the average particle diameter of the titanium oxide ultrafine particle photocatalyst to be applied is preferably 10 nm or less. Also,
The average particle size of the hydroxyapatite fine particle adsorbent is 5μ.
m or less is preferable.

The weight mixing ratio of the titanium oxide ultrafine particle photocatalyst to the hydroxyapatite fine particle is preferably 2: 1 to 1: 2. Outside of this range, the inner wall surface of the coated parallel plate does not act as a complete adsorption surface for nitrogen oxides, which is not preferable. When mixed and applied at this weight mixing ratio, the titanium oxide ultrafine particle photocatalyst and the hydroxyapatite fine particle adsorbent have a large difference as described above, and thus the titanium oxide ultrafine particles are uniformly dispersed around the apatite fine particles. It is in a state.

The higher the proportion of HAP, the more NO_xExcluding
You can leave. However, the TiO _TwoWho have a higher percentage of
The removal efficiency is high. Note that “removal efficiency” uses the following equation.
Means the value calculated. Removal efficiency (%) = 100 (C1-C2) / C1 (C1:
NO concentration before ultraviolet lamp lighting [ppb], C2: ultraviolet
NO concentration [ppb] immediately after lighting of line lamp

FIG. 2 shows that the inner wall surface of the parallel plate has a perfect adsorption surface for nitrogen oxides.
The removal efficiency obtained by the Kennedy's theoretical formula is compared with the removal efficiency (experimental value) of the small parallel plate type diffusion scrubber by the nitrogen oxide removal unit. (1) Ti
O ₂ : average particle size 100 nm / HAP: average particle size 30 μm
In the coated surface of the combination of (2), as shown by the mark ◇, the removal efficiency of nitrogen oxides is a result lower than the theoretical value.
In the case of a coating surface having a combination of iO ₂ : average particle diameter of 7 nm / HAP: average particle diameter of 3 μm, as indicated by a mark, it coincides with the theoretical value line, and is almost 100% at a wind speed of 0.33 m / sec. Removal efficiency is obtained. From this result, TiO ₂ and HAP
It can be understood that a specific combination of the above can form an ideal perfect adsorption surface for nitrogen oxides.

[0027] The removal mechanism of the NO _x by TiO ₂ and HAP, mainly, there are two patterns of the following A, B. (A)
Adsorbed on the HAP surface in the state of NO ₂ . (B) Adsorbed on TiO ₂ surface in HNO ₃ state. The mechanism of A is NO
There can be considered is adsorbed to HAP when it becomes NO ₂ by the photocatalytic reaction of TiO _2, and serves to prevent the on TiO ₂ surface which acts as a photocatalyst HNO ₃ adheres. Therefore, as the ratio of HAP increases, the ratio of removal by the mechanism A increases, and the removal ability can be maintained for a long time. However, as the ratio of TiO ₂ increases, the ability of oxidation from NO to NO ₂ increases, Removal efficiency is higher. However, the oxidizing ability gradually decreases due to the mechanism of B, and the removal efficiency decreases.

The thickness of the coating layer comprising the titanium oxide ultrafine particle photocatalyst and the hydroxyapatite fine particle adsorbent is 10 mg.
/ Cm ² (thickness of several tens μm) is sufficient. NO
_Since the reaction with _x occurs in the surface layer of the coating layer, even if the coating layer is made thicker, it does not contribute to the reaction, so that it is not necessary to make it particularly thick.

As the flow rate of the air increases, the time during which the NO gas stays in the apparatus becomes shorter.
Removal efficiency of O _x is reduced. Also, when the concentration of NO to be introduced is high, the removal efficiency tends to decrease. This is T
Only the amount of radicals generated on the surface of iO ₂ is N
This is because the reaction with O does not occur. If the amount of NO introduced is too large, it does not react even if it diffuses to the wall surface, and the amount of NO passing through the parallel plate type diffusion scrubber increases.

NO by the apparatus of the present invention_xThe removal capacity of
100 mmol per unit coating area of TiO / HAP
/ M^TwoExtremely high and 1 ppm NO_X240 air
0m ^ThreeRemoval processing is possible. Also tunnel
NO in air inside_xConcentrations can reach several ppm
However, as shown in Table 1, the apparatus of the present invention
NO gas removal efficiency of about 100 ppm
%.

The structure of the apparatus for removing nitrogen oxides by the diffusion scrubber method of the present invention has a simple structure and can be easily incorporated into an existing air-conditioning facility or the like. The removal process can be performed efficiently. Therefore, it is possible to provide a high quality living environment by removing the harmful gas components by attaching the nitrogen oxide removing device of the present invention to an air conditioner in a building or the like that has been used for temperature and humidity adjustment.

Further, the nitrogen oxide removing apparatus of the present invention is not only incorporated in the air conditioning equipment of a building, but also generates air-conditioning equipment in an air circulation path such as an automobile tunnel, an underground parking lot, and the like, and generates a small fixed group of construction / construction vehicles. and attached to an exhaust gas treatment apparatus of the source can be performed efficiently NO _X removal process. Further, since the apparatus itself can be easily miniaturized, it can be used as a portable air purifying apparatus in ordinary households, and thus has a very wide range of applications.

[0033]

The atmospheric NO using the diffusion scrubber method of the present invention
Figure removal principle in NO _X atmosphere by _X removal processing apparatus 1
Shown in _Two parallel plates, for example, stainless steel plates (2) coated on the surface with TiO ₂ / HAP (1),
Ultraviolet light is irradiated to the gap between the two stainless steel plates (2) by a UV lamp (5) or the like to activate TiO ₂ .

[0034] The one end as an entrance contaminated air, the flow of contaminated air into the gap two stainless steel plates (3), a large NO _X gas diffusion coefficient (4), TiO ₂ / HAP
It diffuses to the inner wall surface of the stainless steel plate (2) coated with (1). NO _X gas having reached the inner wall surface (4), Ti
NO ₂ by HO _2, OH radicals generated by O _2,
It is oxidized to HNO ₃ , adsorbed on the surface of TiO ₂ / HAP (1), removed from the contaminated air, and the clean air (7) is discharged from the outlet side. TiO ₂ is absorbed NO, N
Because of its low ability to retain O ₂ , it is likely that NO ₂ will desorb before it becomes HNO ₃ . This detached N
To ensure that O ₂ is removed, H ₂ is used as an adsorbent for NO _2.
AP is mixed with TiO ₂ and used.

On the other hand, under the laminar flow condition using the removing device, the particles (6) having a small diffusion coefficient pass through a pair of stainless steel plates (2) as they are without diffusing to the wall surface. And it is discharged | emitted from the exit side of a parallel plate of a pair of stainless steel plates (2). Therefore, in principle, particles in the air do not adhere to the parallel plate of the stainless steel plate, and the influence of the particles on the removing device due to the particles when treating the air is extremely small.

NO ₂ adsorbed on the surface of TiO ₂ or HAP
And HNO ₃ can be easily washed off with water,
It can be used semi-permanently by washing regularly applied surfaces with water. Activated carbon is also known as an adsorbent, but in the case of activated carbon, it is difficult to wash and reuse it.

Thus, the use of the diffusion scrubber method is completely different from the principle of a chemical filter for filtering contaminated air.
Since the contaminated air is caused to flow through the gap between the pair of parallel plates, the pressure loss due to the ventilation resistance is extremely small, and a large amount of contaminated air can be purified with small energy.

[0038]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is based on the principle of the "diffusion scrubber method", in which contaminated air is caused to flow through a narrow gap between a pair of parallel plates facing in parallel, and the gas diffused on the inner wall surface of the parallel plates. This is a method of removing components on the inner wall surface, and can continuously remove harmful gases while flowing contaminated air.

Specifically, ultrafine titanium oxide (TiO ₂ ) particles and hydroxyapatite (HAP) fine particles are applied to the inner wall surfaces of the parallel plate to be removed, and nitrogen oxides are added while air flows through the gap between the parallel plates. Is oxidized to NO ₂ and HNO ₃ and removed. Then, the N collected and removed on the inner wall surface
O ₂ and HNO ₃ can be easily washed and recovered with water, and if necessary, nitrogen oxides in the air can be repeatedly and continuously removed.

The parallel plate is preferably a stainless steel plate having excellent corrosion resistance, but is not limited to the stainless steel plate. Most preferably, the TiO ₂ ultrafine particles applied to the parallel plate have an average particle size of about 7 nm. The average particle size of the HAP fine particles is most preferably about 3 μm. The TiO ₂ ultrafine particles and the HAP fine particles are mixed in an organic solvent such as acetone so that the weight ratio becomes 2: 1 to 1: 2, and a binder such as polytetrafluoroethylene is appropriately added thereto, and a known coating means is used. For example, application is performed by a spray gun or the like so that the thickness after drying is about 10 mg / cm ² (thickness of several tens μm).

By using two parallel plates (2) facing each other with the coating surfaces facing each other, as shown in FIG. 3, the holding members 8 at both ends of the parallel plates are fixed to the fixing members 9 at a narrow interval of about 5 mm. With a very small U in the gap at one end of the parallel plate (2).
A V lamp (5) is installed so that the gap can be irradiated with ultraviolet light, and a nitrogen oxide removing unit by a small parallel plate type diffusion scrubber method.

The size of this unit is 440 ×
150 × 38 mm, the ventilation channel surface coated with TiO ₂ / HAP is 350 × 100 mm (area, 350 cm ² )
It is. This unit is used alone or in combination with a predetermined number to form a nitrogen oxide removing device, which is attached to an air conditioner or the like, and contaminated air is caused to flow through the gap between the parallel plates (2), and ultraviolet light is applied to the photocatalytic surface by a UV lamp (5). When irradiated, NO _X
Is oxidized and adsorbed and removed by TiO ₂ / HAP on the inner wall surface.

As shown in FIG. 1, nitrogen oxides (NO, NO ₂ ) were formed on TiO ₂ / HAP under ultraviolet irradiation.
Is oxidized to NO ₂ or HNO ₃ and adsorbed and removed. Then, TiO is washed by injecting water and washing.
The nitrogen oxides are oxidized and adsorbed on the ₂ / HAP NO ₂ ^-,
It can be easily recovered with water as NO ₃ ^- ions.

The NO ₂ ^- and NO ₃ ^- ions recovered with water are:
Easy treatment with ion exchange resin. Then, if the TiO ₂ / HAP surface is dried by flowing air after washing with water, it is possible to repeatedly remove nitrogen oxides (NO, NO ₂ ). In this way, the removal treatment apparatus of the present invention can remove nitrogen oxides (NO, NO ₂ ) while circulating water for a long period of time.

[0045]

EXAMPLE 1 TiO ₂ powder (Wako Pure Chemical Industries, average particle size 100 nm) and HAP powder (Shinshu ceramics, average particle size 30 μm) were used in a ratio of 33.3% by weight: 33.3% by weight. 3% by weight of a tetrafluoroethylene resin binder (TiO ₂ : H
AP: PTFE = 1: 1: 1) and an organic solvent such as acetone were mixed, applied to the surface of a stainless steel plate by a spray gun, and dried. The unit shown in FIG. 3 described in the embodiment was manufactured using this stainless steel plate. As the UV lamp, an outer diameter of 4 mmφ (Toshiba cold cathode fluorescent lamp) was used.

This unit was subjected to an evaluation test as follows. NO supplied from a standard gas cylinder of NO
The gas is appropriately diluted with clean air to a concentration level of several ppm, and the diluted NO gas is introduced into a small parallel plate type diffusion scrubber removal device without turning on the UV lamp (5) and passed through the device. The NO concentration of the subsequent gas was measured.
After confirming that the NO concentrations at the inlet and the outlet of the removing device coincided with each other, the UV lamp (5) was turned on, and the removal efficiency of NO by the removing device was calculated from the change in the NO concentration at the removing device outlet after the lamp was turned on. The removal efficiency was determined by the above-described equation.

Ventilation flow rate 4 L / min, NO concentration 673 p
NO for contaminated air treatment when air is treated under pb conditions
FIG. 4 shows the change over time in the concentration change and the NO _x removal efficiency. According to FIG. 4, when the UV lamp (5) is turned on, 673p
The NO concentration of pb drops rapidly to 75 ppb or less,
It can be seen that the NO concentration after passing through the removing device gradually increases with time. This is because H attached to TiO ₂
This is because NO ₃ prevents light from hitting TiO ₂ . However, no significant decrease in the removal efficiency was observed even after about 7 hours, and when the UV lamp was turned off, the NO concentration returned to 673 ppb before the lamp was turned on. From FIG. 4, it was confirmed that in Example 1, NO _X could be removed with a high removal efficiency of 80% or more.

Example 2 Using the same apparatus as in Example 1, the ventilation flow rate was 4 L / mi.
n, NO concentration 2705ppb, ventilation flow rate 10L / mi
When air was treated under the respective conditions of n and NO concentration of 2645 ppb, the removal efficiency was 83.0 as shown in Table 1.
% Was 46.0%. FIG. 5 shows the change with time of the NO concentration when the contaminated air was treated under the conditions described above.

[Table 1]

Example 3 As TiO ₂ , the average particle size was 7 nm (Ishihara Sangyo ST-0)
1) The same apparatus as in Example 1 except that the average particle size was 3 μm (Tomita Pharmaceutical Co., Ltd.) as the HAP, and the ventilation flow rate was 4 L / mi.
n, NO concentration 3205 ppb, ventilation flow rate 10 L / mi
n, NO concentration 3341 ppb, ventilation flow rate 15 L / mi
When the contaminated air was treated under the respective conditions of n and NO concentration of 3222 ppb, the removal efficiency was 10 as shown in Table 1.
Very high removal efficiencies of 0.0%, 95.7% and 89.0% were obtained. FIG. 6 shows the change with time of the NO concentration and the removal efficiency when the contaminated air was treated under the conditions described in FIG.

Example 4 Using the same apparatus as in Example 1, the change with time of the NO concentration when the contaminated air was treated under the conditions of Example 2 while changing the ratio of TiO ₂ : HAP to 1: 2 was performed. FIG. 5 shows a comparison with the condition of Example 2. From FIG. 5, the initial NO removal efficiency is slightly better in the case of TiO ₂ : HAP = 1: 1 in Example 2, but the NO removal capacity is TiO ₂ : HAP = 1: 2 in Example 4. Was better.

Example 5 A rectangular parallelepiped device was manufactured by bundling 50 units of the nitrogen oxide removing device using a small parallel plate type diffusion scrubber shown in FIG. A titanium oxide ultrafine particle photocatalyst (Ishihara Sangyo ST-01, average particle diameter 7 nm) and hydroxyapatite fine particles (Tomita Pharmaceutical, average particle diameter 3 μm) were applied to a stainless steel plate in an area of 50 × 50 cm using a tetrafluoroethylene resin binder. . Has a removal capacity of 250 times the nitrogen oxide NO _X miniature parallel plate diffusion scrubber nitrogen oxide removal equipment unit by the device, every minute 2.5 m ³ (1
50 m ³ / h) of air could be treated.

[0052]

The nitrogen oxide removal treatment apparatus of the present invention
Ultrafine titanium oxide photocatalyst and hydroxyapatite (H
AP) It is a simple structure removal processing device using a parallel plate coated with a gas adsorbent. Particles in the air pass through the parallel plate removal device in principle and do not adhere to the inner wall surface of the parallel plate. it is the influence of dirt on the removal device small, the NO _X was removed using a simple water as a wash NO ₂ ^- and NO ₃ ^- as easy recovery, repeated continuously can be used if dry removal device, washing liquid The existing ion-exchange resin can also be used for the regeneration process, which is excellent in terms of energy saving and running cost. Unlike filtration and collection by a filter, the ventilation resistance is small and the air throughput is extremely large. It has a high practical value because it has a simple structure, can be moved, and can be easily incorporated into existing air conditioners such as tunnels and indoor parking lots.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing the principle of a nitrogen oxide removal treatment apparatus by a parallel plate type diffusion scrubber using a mixture of TiO ₂ ultrafine particles and hydroxyapatite fine particles.

FIG. 2 is a graph showing a comparison between the theoretical efficiency of atmospheric nitrogen oxides calculated from the Gormley-Kennedy theoretical formula and experimental values.

FIG. 3 is a perspective view of a nitrogen oxide removal treatment apparatus using a parallel plate type diffusion scrubber method of the present invention.

FIG. 4 is a diagram illustrating NO in the contaminated air treatment according to the first embodiment.
Is a graph showing the change in concentration and NO _X removal efficiency.

FIG. 5 is a graph showing a change in NO concentration in the contaminated air treatment in Examples 2 and 4.

FIG. 6 is a diagram illustrating NO in the processing of contaminated air according to the fourth embodiment.
Is a graph showing the change in concentration and NO _X removal efficiency.

FIG. 7 is a schematic diagram of a diffusion scrubber method for a calculation formula of the removal efficiency of atmospheric gas components based on the Gormley-Kennedy theoretical formula.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B01D 53/94 B01D 53/36 J B01J 27/18 53/34 ZAB 35/02 129A F01N 3/08 53 / 36 ZAB 3/10 101A 3/24 (72) Inventor Kazuaki Iijima 1-4-1 Yurakucho, Chiyoda-ku, Tokyo Sanki Kogyo Co., Ltd. F-term (reference) 3G091 AA02 AA05 AA06 AB01 AB09 BA14 BA38 BA39 GB00Y GB01W GB01Z GB10W 4D002 AA12 BA04 BA05 BA09 CA07 CA20 DA70 EA02 GA01 GA02 GB02 GB12 4D048 AA06 AB03 BA07X BA41X BA44X BB03 CA10 CC40 EA01 EA04 4G069 AA03 AA08 BA04A BA04B BA48A BB14A BB14B BC09ABC09BBD07

Claims (5)

[Claims] Claims: 1. An air flow through a narrow gap between a pair of parallel plates,
Nitrogen oxide in the air diffuses to the inner wall surface of the parallel plate while flowing in the parallel plate, and is adsorbed and removed on the inner wall surface provided with a coating layer composed of titanium oxide ultrafine particle photocatalyst and hydroxyapatite fine particle adsorbent. Removal equipment for nitrogen oxides in the atmosphere. 2. The specification of the removal treatment apparatus is set by Gormley-Kennedy's theoretical formula assuming that the inner wall surface of the parallel plate is an ideal perfect adsorption surface for nitrogen oxides. 2. The apparatus for removing nitrogen oxides from the atmosphere according to claim 1. 3. A coating layer comprising a titanium oxide ultrafine particle photocatalyst and a hydroxyapatite fine particle adsorbent is provided on the inner wall surfaces of the pair of parallel plates to realize a complete adsorption surface of nitrogen oxides. The apparatus for removing nitrogen oxides in the atmosphere according to claim 1 or 2. 4. The titanium oxide ultrafine particle photocatalyst is ultrafine particles having an average particle size of 10 nm or less, and the hydroxyapatite fine particle adsorbent is a fine particle having an average particle size of 5 μm or less.
4. The apparatus for removing nitrogen oxides from the atmosphere according to claim 1, wherein the weight ratio of the titanium oxide ultrafine particle photocatalyst to the hydroxyapatite fine particle is 2: 1 to 1: 2. 5. The removal of nitrogen oxides in the air according to claim 1, wherein the nitrogen oxide is attached to an air flow path of an air conditioner or a gas flow path of an exhaust gas treatment device. Processing equipment.