JP2743043B2 - Adsorption remover for low concentration nitrogen oxides - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is intended to efficiently reduce low-concentration nitrogen oxides (NOx) contained in ventilation gas in various tunnels such as various road tunnels, mountain tunnels, submarine tunnels, underground roads, shelter roads and the like. It relates to an adsorptive removal agent that removes well.

[0002]

BACKGROUND OF THE INVENTION In various road tunnels, mountain tunnels, underground roads, shelter roads, and the like (in the present specification, these tunnels are collectively referred to as "road tunnels"), especially in a large-sized automobile traffic. For large volumes, substantial ventilation needs to be provided to protect the health of passersby and improve the visibility distance. Also, even in a relatively short tunnel, in an urban area or in a suburban area, air in the tunnel is suctioned and exhausted (ventilated) as a method of preventing air pollution due to carbon monoxide (CO), NOx, etc. concentrated at the entrance. There is a way.

However, if the ventilation gas is directly radiated to the surroundings, it does not improve the local environment. In particular, a highly contaminated area is expanded in or near an urban area where the pollution caused by automobile exhaust gas is spread flatly. It can be made to do. Tunneling as an anti-pollution measure for existing roads,
The same is true when installing a shelter.

The present invention relates to an adsorbent for efficiently removing low-concentration NOx contained in such a ventilation gas as a road tunnel.

[0005]

2. Description of the Related Art Ventilation gases in various tunnels are characterized by a low NOx concentration of about 5 ppm, a gas temperature at room temperature, and a large fluctuation in gas flow according to traffic volume.

[0006] Methods of removing NOx from stationary sources, which have been studied for the purpose of purifying various types of boiler combustion exhaust gas, are roughly classified into the following three methods.

(1) Catalytic reduction method This is a method in which ammonia is used as a reducing agent and NOx in exhaust gas is selectively reduced to harmless nitrogen and water vapor, and is the most common method for denitrification of boiler exhaust gas. is there. However, in this method, since the processing gas temperature needs to be 200 ° C. or more, when the gas amount is large at room temperature, such as a ventilation gas for a road tunnel, a large amount of energy is required to raise the temperature of the processing gas. Therefore, it is not an economical processing method.

(2) Wet absorption method This method uses nitrogen dioxide (NO ₂ ) or nitrogen trioxide (N
_This method utilizes the fact that ₂ O ₃ ) is absorbed by water or an aqueous alkaline solution. It is possible to oxidize nitrogen monoxide (NO) by injecting an oxidation catalyst or ozone and then absorb it, or to add oxidizing properties to the absorbing solution. Are known. However, in these methods, since NOx is accumulated in the absorbing solution as nitrate or nitrite, management and post-treatment of the absorbing solution are required, and the process becomes complicated. Further, the unit price per mole of the oxidizing agent is higher than that of ammonia used in the catalytic reduction method, and there is a problem in the economics of the process.

(3) Dry adsorption method This is a method of adsorbing and removing NOx in exhaust gas using an appropriate adsorbent, and several studies have been conducted until the catalytic reduction method is established as a denitrification method of boiler exhaust gas. However,
Since boiler exhaust gas has (a) a high NOx concentration, (b) a high gas temperature, and (c) a high water concentration, the dry adsorption method is inferior in economic efficiency to the catalytic reduction method and has been put into practical use until now. Not.

However, when the dry adsorption method was evaluated as a method for purifying ventilation gas in a road tunnel or the like, it was found that the process was simple and economical, completely different from the case of boiler exhaust gas.

[0011]

SUMMARY OF THE INVENTION As an adsorbent for low-concentration NOx, the present inventors have previously used natural or synthetic adsorbents intended to efficiently adsorb and remove NOx at a low concentration of 5 ppm. A low-concentration NOx adsorption / removal agent in which zeolite carries at least one copper salt selected from copper chloride, a double salt of copper chloride and an ammine complex salt of copper chloride (see Japanese Patent Application Laid-Open No. 1-299624). And adsorbent for removing vanadium from a carrier comprising anatase type titania (Japanese Patent Application No. 2-340627).
No.), respectively.

However, these adsorbents have a problem that when the water (or moisture) concentration is high, the adsorption performance is deteriorated (deterioration phenomenon).

Therefore, these adsorbents must have a moisture concentration of about -35 ° C. or less (about 200 ppm or less) at a dew point in order to exhibit good adsorption performance. It is necessary to provide a dehumidification step in the first stage and dehumidify (dehumidify) the gas to be treated.

If an adsorbent removing agent not affected by moisture is developed, the NOx removing device can be reduced in size and energy saving, and its economical effect is high. Is eagerly awaited.

The present inventors have proposed, as an adsorbent that functions even under such high humidity, an adsorbent removing agent in which ruthenium is supported on a carrier made of γ-alumina (Japanese Patent Application No. Hei.
194513).

However, since the carrier (alumina oxide; Al ₂ O ₃ ) is sulfated by the sulfur oxide (SOx) contained in the processing gas, the adsorption / removal agent requires the carrier to be sulfated. Has the disadvantage that the adsorption performance is reduced depending on the degree of

As a countermeasure, the present inventors have proposed an adsorption remover characterized in that ruthenium is supported on a ceramic paper carrier holding anatase type titania (Japanese Patent Application No. 3-286277). reference).

[0018] However, this adsorbent remover has a very good initial performance, but has a disadvantage that its performance is considerably deteriorated when exposed to a high temperature exhaust gas of 250 ° C or more for a long time. It is considered that the reason for this decrease in activity is that under high temperature conditions, halogen is eliminated from the ruthenium halide as an active component, and the resulting RuO ₂ has only a poor activity.

An object of the present invention is to provide an adsorptive / removing agent capable of maintaining high activity for a long period of time without releasing halogen from ruthenium halide even under high temperature conditions, thereby contributing to miniaturization and energy saving of the NOx removing device. It is what it was.

[0020]

Means for Solving the Problems The present inventors have conducted various studies to achieve the above object, and as a result, have found that a gas containing a low concentration of NOx can be transferred onto an anatase-type titania carrier having a specific shape by using a ruthenium halogen. By co-supporting a halide and a halide of a specific metal, it has been found that halogen is not eliminated from a ruthenium halide even under high temperature conditions, and the present invention has been completed.

That is, the low concentration NOx adsorption / removal agent (hereinafter simply referred to as an adsorbent) according to the present invention comprises a ruthenium halide, potassium, sodium, magnesium, calcium and manganese on a ceramic paper carrier holding anatase titania. , Copper, zinc, rubidium,
At least one metal halide selected from the group consisting of zirconium, barium, cerium, and molybdenum is co-supported.

In order to produce the low concentration NOx adsorption / removal agent of the present invention, ceramic paper is impregnated with anatase-type titania sol and dried or calcined to obtain a carrier. Then, the carrier is coated with a ruthenium halide, potassium, Sodium, magnesium, calcium, manganese, copper, zinc, rubidium, zirconium, barium,
It is impregnated with at least one metal halide selected from the group consisting of cerium and molybdenum (hereinafter, referred to as metal halide) and dried or fired.

The ceramic paper is produced by making ceramic fibers. Commercially available ceramic paper can also be used.

As anatase type titania sol, for example, hydrated titania (titanate slurry) or titanate slurry, which is an intermediate product during the production of titania by a sulfuric acid method, is peptized.
A stabilized one is used.

The anatase-type titania tends to have a higher NOx adsorption performance as its retention amount increases. When the retained amount of anatase-type titania is 20 g / m ² or less,
Since the NOx adsorption performance drops rapidly, the retention amount is preferably 20 g / m ² or more.

Next, a ruthenium halide and a metal halide are co-supported on the carrier.

The loading of ruthenium is preferably about 0.01% by weight or more, more preferably about 0.1 to 5% by weight of the final adsorbent as ruthenium metal. The metal halide is preferably carried in an amount of about 0.1% by weight or more of the final adsorbent as a metal, and more preferably about 1 to 10% by weight.
% By weight is preferred. The co-supporting of a ruthenium halide and a metal halide is generally performed by dissolving a ruthenium halide such as ruthenium chloride (RuCl ₃ ) and a metal halide such as the above-mentioned metal chloride in an appropriate solvent. This is performed by immersing the carrier in a mixture solution. However, this method is not limited.

After immersion, the adsorbent is separated from the mixture solution,
After washing with water, it is dried at about 100 to 120 ° C. in the air. The dried product is fired at about 300 to 500 ° C. as necessary. In the case of continuous use by repeated adsorption, desorption, regeneration, etc., treatment at a temperature slightly higher than the maximum use temperature of the adsorbent may be necessary.

It is considered that the ruthenium halide and the metal halide co-supported on the carrier are complexed or form a stable salt.

NOx adsorbed on the adsorbent is easily desorbed by heating. Therefore, regeneration of the adsorbent can be easily performed.
Therefore, the adsorbent according to the present invention can be suitably used as an adsorbent for a rotary NOx adsorption rotor that continuously repeats adsorption and desorption (regeneration) of NOx.

Like ventilation gas from a road tunnel or the like,
When processing a large amount of gas, it is necessary to reduce the flow resistance and the pressure loss as much as possible. Therefore, a ruthenium halide and a metal halide are deposited on an adsorbent carrier having a multilayer structure of a flat plate and a corrugated plate in which a flat anatase-type titania holding ceramic paper and a corrugated anatase-type titania holding ceramic paper are alternately arranged. Is desirably a honeycomb-shaped adsorbent in which is co-supported.

[0032]

EXAMPLES Examples of the present invention and some comparative examples to be compared with the examples will be described below.

Example 1 Commercially available ceramic paper (manufactured by Nippon Inorganic Co., Ltd., components:
Silica: alumina = 50: 50, thickness: 0.25 mm, basis weight: 46 g / m ² ) were cut into predetermined dimensions and immersed in anatase-type titania sol (TiO ₂ content: about 30% by weight) at room temperature. did. Immediately after immersion, the ceramic paper was taken out on a flat plate, excess titania sol was dropped by a roller or the like to obtain a uniform thickness, and dried with hot air. The thus formed flat-plated titania sol-impregnated ceramic paper was placed in an electric furnace, and was placed in air at 400 ° C. for 3 hours.
After sintering for a time, a plate-like titania-supporting ceramic paper carrier was obtained.

Further, the ceramic paper having been immersed in the anatase-type titania sol was taken out on a corrugated sheet, and thereafter the same operation as above was performed to obtain a corrugated titania-supporting ceramic paper carrier.

From the difference between the weight before the impregnation with the titania sol and the weight after the calcination, the amount of TiO ₂ carried was determined.
m ² of TiO ₂ was retained.

By the above operation, a plurality of plate-like titania-supporting ceramic paper carriers having different widths and a plurality of corrugated plate-like titania-holding ceramic paper carriers also having different widths were produced. Then, as shown in FIG.
A flat plate (1) and corrugated plate (2) of required width are stacked alternately to form a columnar stacked body, which is temporarily bound with a ceramic paper band, and an adsorbent with a flat plate / corrugated plate multilayer structure Carrier (external dimensions; diameter 22 mm x length 50 mm, geometric surface area: 0.03
85 m ² , weight; 4.3 g (TiO ₂ content: 3.3
g) was obtained.

The adsorbent carrier having a multilayer structure of flat plate and corrugated plate is composed of ruthenium chloride (RuCl ₃ ) and manganese chloride (MnCl).
₂ ) in 100 ml of an aqueous solution (Ru concentration; 0.38% by weight, Mn concentration; 2.07% by weight) containing
Soak for minutes. Then, after washing with water, it is dried at about 110 ° C. for 2 hours, and dried in a honeycomb form with a Ru—Mn co-supported titania adsorbent (Ru supported amount: 0.55% by weight, Mn supported amount;
3.00% by weight).

The adsorbent was filled in a stainless steel reaction tube (3) having an inner diameter of 22 mm, and the band for temporary binding was removed. Then, the adsorbent was treated for 1 hour in a stream of dry air (moisture concentration: about 50 ppm) at about 300 ° C. (2.5 NL / min), and then allowed to cool to room temperature. After cooling, the flow of dry air was temporarily stopped, and humidified air (2.5 NL / min) with a moisture concentration of 500 ppm containing 3.5 ppm of NOx was introduced into the adsorbent layer. The NOx concentration in the sample was measured with a chemiluminescence analyzer. FIG. 2 shows the change over time in the NOx concentration in the outlet gas as Example 1 (before heat treatment). It should be noted that the vertical axis in FIG. 2 shows a value obtained by dividing the NOx concentration in the outlet gas by the NOx concentration in the inlet gas (referred to as “breakthrough rate”).

As is clear from the curve of Example 1 (before heat treatment) in the figure, the NOx concentration in the outlet gas reached 5% of the inlet concentration (breakthrough rate: 0.05), that is, 0.175 ppm. The time required to do so (called “breakthrough time”) is 33.
It was 0 minutes.

Next, this adsorbent was heat-treated in the air at 250 ° C. for 100 hours, and then the NOx absorption characteristics were measured by the same method and under the same conditions. FIG. 2 shows the change over time in the NOx concentration in the outlet gas as Example 1 (after the heat treatment).
As is clear from the curve of Example 1 (after the heat treatment), the breakthrough time when the breakthrough rate became 0.05 was 27 minutes.

[0041] As Comparative Example 1 immersion liquid, ruthenium chloride (RuCl ₃₎ water; except using (Ru concentration 0.38 wt%) 100 ml, performs the same operation as in Example 1, Ru supported titania adsorbent (Ru supported 0.55% by weight).

The NOx absorption characteristics of this adsorbent were measured in the same manner as in Example 1 under the same conditions. The change with time of the NOx concentration in the outlet gas is shown as Comparative Example 1 in FIG. As is clear from the curve of Comparative Example 1, the breakthrough time when the breakthrough rate became 0.05 was 40 minutes.

Next, this adsorbent is heat-treated under the same conditions as in Example 1, and then N is applied under the same conditions and under the same conditions as in Example 1.
Ox absorption characteristics were measured. FIG. 2 shows the change over time of the NOx concentration in the outlet gas as Comparative Example 1 (after heat treatment). As is clear from the curve of Comparative Example 1 (after the heat treatment), the breakthrough time when the breakthrough rate became 0.05 was 5 minutes.

Example 2 As an immersion liquid, a mixed aqueous solution containing ruthenium chloride (RuCl ₃ ) and cerium chloride (CeCl ₃ ) (Ru concentration: 0.38% by weight, Ce concentration: 5.32% by weight) 10
The same operation as in Example 1 was performed except that 0 ml was used, and Ru was used.
A Ce co-supported titania adsorbent (Ru supported amount: 0.55% by weight, Ce supported amount: 7.70% by weight) was prepared.

The NOx absorption characteristics of this adsorbent were measured in the same manner as in Example 1 under the same conditions. FIG. 3 shows the change with time of the NOx concentration in the outlet gas as Example 2 (before heat treatment). As is clear from the curve of Example 2 (before heat treatment), the breakthrough time when the breakthrough rate became 0.05 was 14 minutes.

Next, this adsorbent is heat-treated under the same conditions as in Example 1, and then NOx is produced under the same conditions and under the same conditions as described above.
The absorption characteristics were measured. FIG. 3 shows the change over time in the NOx concentration in the outlet gas as Example 2 (after the heat treatment). Example 2
As is clear from the curve (after the heat treatment), the breakthrough rate was 0.1%.
The breakthrough time when it reached 05 was 35 minutes.

Example 3 As an immersion liquid, a mixture aqueous solution containing ruthenium chloride (RuCl ₃ ) and potassium chloride (KCl) (Ru concentration;
The same operation as in Example 1 was performed except that 100 ml of 0.38% by weight, K concentration; 0.29% by weight) was used, and the Ru / K co-supported titania adsorbent (Ru supported amount; 0.55% by weight, K
(Supporting amount: 0.42% by weight).

The NOx absorption characteristics of this adsorbent were measured in the same manner as in Example 1 under the same conditions. FIG. 4 shows the change with time of the NOx concentration in the outlet gas as Example 3 (before heat treatment). As is clear from the curve of Example 3 (before heat treatment), the breakthrough time when the breakthrough rate became 0.05 was 14 minutes.

Next, this adsorbent is heat-treated under the same conditions as in Example 1, and then NOx is applied under the same conditions and under the same conditions as described above.
The absorption characteristics were measured. FIG. 4 shows the change with time of the NOx concentration in the outlet gas as Example 3 (after heat treatment). Example 3
As is clear from the curve (after the heat treatment), the breakthrough rate was 0.1%.
The breakthrough time when it reached 05 was 20 minutes.

Examples 4 to 12 In Example 4, ruthenium chloride (RuC) was used as the immersion liquid.
l ₃ ) and sodium chloride (NaCl), except that an aqueous mixture was used.
-Na co-supported titania adsorbent (Ru supported amount: 0.55% by weight, Na supported amount: 1.25% by weight) was prepared.

In Example 5, ruthenium chloride (RuCl ₃ ) and magnesium chloride (MgCl ₂ ) were used as immersion liquids.
The same operation as in Example 1 was performed except that a mixture aqueous solution containing the following was used, and a Ru / Mg co-supported titania adsorbent (Ru supported amount: 0.55% by weight, Mg supported amount: 1.32% by weight)
Was prepared.

In Example 6, the same operation as in Example 1 was carried out except that an aqueous mixture containing ruthenium chloride (RuCl ₃ ) and calcium chloride (CaCl ₂ ) was used as the immersion liquid. An adsorbent (Ru loading: 0.55% by weight, Ca loading: 2.18% by weight) was prepared.

In Example 7, the same operation as in Example 1 was carried out except that an aqueous mixture containing ruthenium chloride (RuCl ₃ ) and copper chloride (CuCl ₂ ) was used as the immersion liquid. Adsorbent (Ru supported amount;
0.55% by weight, Cu loading: 3.46% by weight).

In Example 8, the same operation as in Example 1 was carried out except that an aqueous mixture containing ruthenium chloride (RuCl ₃ ) and zinc chloride (ZnCl ₂ ) was used as the immersion liquid. Adsorbent (Ru supported amount;
0.55% by weight, Zn loading: 3.56% by weight).

In Example 9, the same operation as in Example 1 was carried out except that an aqueous mixture containing ruthenium chloride (RuCl ₃ ) and rubidium chloride (RbCl) was used as the immersion liquid. An agent (Ru loading: 0.55% by weight, Rb loading: 4.66% by weight) was prepared.

In Example 10, ruthenium chloride (RuCl ₃ ) and zirconium chloride (ZrC
except that a mixture aqueous solution containing l ₄₎ and is, in Example 1
The same operation as described above was carried out, and the Ru / Zr co-loaded titania adsorbent (Ru loading: 0.55% by weight, Zr loading: 4.97)
% By weight).

In Example 11, the same operation as in Example 1 was carried out except that an aqueous mixture containing ruthenium chloride (RuCl ₃ ) and barium chloride (BaCl ₂ ) was used as the immersion liquid. An adsorbent (Ru loading: 0.55% by weight, Ba loading: 7.48% by weight) was prepared.

In Example 12, ruthenium chloride (RuCl ₃ ) and molybdenum chloride (MoCl ₅ ) were used as immersion liquids.
The same operation as in Example 1 was performed except that a mixture aqueous solution containing the following was used: Ru / Mo co-supported titania adsorbent (Ru supported amount: 0.55% by weight, Mo supported amount: 5.22% by weight)
Was prepared.

The NOx absorption characteristics of these adsorbents were measured in the same manner as in Example 1 under the same conditions. For each adsorbent, the breakthrough time when the breakthrough rate became 0.05 was as shown in the column before heat treatment in Table 1.

Next, these adsorbents were heat-treated under the same conditions as in Example 1, and then N2 was applied under the same conditions and under the same conditions as described above.
Ox absorption characteristics were measured. For each adsorbent, the breakthrough time when the breakthrough rate became 0.05 was as shown in the column after heat treatment in Table 1.

Comparative Examples 2 to 4 In Comparative Example 2, ruthenium chloride (RuC) was used as the immersion liquid.
l ₃ ) and bismuth chloride (BiCl ₃ ), except that an aqueous mixture was used.
A Bi-supported titania adsorbent (Ru loading: 0.55% by weight, Bi loading: 11.38% by weight) was prepared.

In Comparative Example 3, the same operation as in Example 1 was carried out, except that a mixed aqueous solution containing ruthenium chloride (RuCl ₃ ) and tin chloride (SnCl ₂ ) was used as the immersion liquid, and the Ru—Sn co-supported titania was used. Adsorbent (Ru supported amount;
0.55% by weight, Sn loading: 6.46% by weight).

In Comparative Example 4, the same operation as in Example 1 was carried out except that an aqueous mixture containing ruthenium chloride (RuCl ₃ ) and antimony chloride (SbCl ₅ ) was used as the immersion liquid. An adsorbent (Ru loading: 0.55% by weight, Sb loading: 6.63% by weight) was prepared.

The NOx absorption characteristics of these adsorbents were measured in the same manner as in Example 1 under the same conditions. For each adsorbent, the breakthrough time when the breakthrough rate became 0.05 was as shown in the column before heat treatment in Table 1.

Next, these adsorbents were heat-treated under the same conditions as in Example 1 and then N 2 was applied under the same conditions and under the same conditions as described above.
Ox absorption characteristics were measured. For each adsorbent, the breakthrough time when the breakthrough rate became 0.05 was as shown in the column after heat treatment in Table 1.

Performance evaluation

[Table 1] As is clear from FIGS. 2 to 4 showing the NOx adsorption characteristics of each adsorbent and Table 1, each of the adsorbents of the Examples was 25%.
Even when exposed to a high-temperature atmosphere at 0 ° C. for 100 hours, sufficient activity can be maintained. Therefore, it is suggested that these adsorbents can be used continuously by repeating adsorption and regeneration.

On the other hand, each of the adsorbents of the comparative example is not inferior to the adsorbent of the example in terms of initial performance, but shows a remarkable decrease in performance when exposed to a high-temperature atmosphere at 250 ° C. for 100 hours. .

Desorption regeneration temperature of adsorbed NOx After adsorbing and removing NOx according to Example 1, air adjusted to a moisture concentration of 500 ppm was added to the reaction tube at 2.5 NL / hour.
The temperature of the adsorbent was raised while flowing in minutes. FIG. 5 shows the change in the NOx concentration in the gas at the outlet of the reaction tube in this case.

As can be seen from the figure, as the temperature of the adsorbent increases, the amount of desorbed NOx increases, and as a result, the outlet NOx concentration sharply increases.

On the other hand, the N remaining in the adsorbent due to desorption
As the amount of Ox decreases, the amount of desorbed NOx decreases and the outlet N
The Ox concentration also decreases. Therefore, the outlet NOx concentration becomes a curve having a peak (called a desorption peak). In the case after NOx adsorption removal using the adsorbent of Example 1, the desorption peak was about 190 ° C.

On the other hand, when NOx was adsorbed and removed using the adsorbent of Comparative Example 1 and this adsorbent was desorbed by the same operation as described above, the desorption peak was about 24 as shown in FIG.
It was 0 ° C.

As a result, the adsorbent of Example 1 can desorb adsorbed NOx at a lower temperature and can regenerate the adsorbent more easily than the adsorbent of Comparative Example 1. I understand.

Example 13 (Effect of Moisture Concentration) A Ru-supported titania adsorbent prepared in the same manner as in Example 1 was charged into a reaction tube in the same manner as in Example 1, dried under the same conditions, and allowed to cool. The flow of the dry air is stopped once, and the conditioned air containing 3.5 ppm of NOx as a reactive gas in the adsorbent layer (moisture concentration: about 22,000 ppm, temperature: 26.0 ° C.,
(Relative humidity; 51%) at a rate of 2.5 NL / min, and the NOx concentration in the reaction tube outlet gas was measured. The change over time in this concentration is shown in FIG. FIG. 3 also shows the results of Example 1 (moisture concentration; about 500 ppm).

In FIG. 7, as is clear from the comparison of the two curves having different moisture concentrations, the NOx adsorption performance does not decrease even if the moisture concentration increases, and NOx can be efficiently removed even when the moisture concentration in the atmospheric air is high. It turns out that adsorption removal is possible.

Ru carrying amount An adsorbent carrier having a laminated structure of a flat plate and a corrugated plate was prepared in the same manner as in Example 1. This adsorbent carrier is mixed with an aqueous solution mixture containing a predetermined concentration of ruthenium chloride and manganese chloride (Ru concentration;
(0.2-0.3% by weight, Mn concentration: 2.07% by weight) at room temperature for a required time, washed with water, dried, and Ru
Adsorbents with different loading amounts were obtained.

These adsorbents were filled in a reaction tube in the same manner as in Example 1, the NOx concentration in the outlet gas was measured under the same conditions, and the 10% breakthrough time (when the NOx concentration in the outlet gas was less than the inlet concentration) (Time to reach 10%). FIG. 8 shows the relationship between the amount of Ru supported and the 10% breakthrough time.

As can be seen from the figure, the 10% breakthrough time increases as the amount of loaded Ru increases, that is, NO
Although x adsorption performance is improved, it can be seen that the 10% breakthrough time becomes almost constant when the amount of supported Ru is about 2% by weight or more.

[0078]

The adsorbent according to the present invention comprises a ceramic paper carrier holding anatase titania, a ruthenium halide, potassium, sodium, magnesium, calcium, manganese, copper, zinc, rubidium,
Since it is co-supported with a halide of at least one metal selected from the group consisting of zirconium, barium, cerium, and molybdenum, 10 ° C. at 250 ° C.
Even when exposed to a high-temperature atmosphere for 0 hours, sufficient activity can be maintained. Therefore, this adsorbent is suitable for continuous use by repeating adsorption and regeneration.

Further, this adsorbent has a higher NOx adsorbing performance per TiO ₂ weight and a higher NOx adsorbing performance per Ru supported amount as compared with the ruthenium-only adsorbent.
Furthermore, desorption of adsorbed NOx can be performed at lower temperature,
It is an excellent adsorbent in that the regeneration of the adsorbent is easy.

Since the adsorbent is not affected by moisture like the adsorbent supporting ruthenium alone, the dehumidification step required in the preceding stage of NOx adsorption and removal can be omitted or reduced. Therefore, a large amount of energy required in the dehumidifying step can be reduced, and a dehumidifying device can be eliminated or simplified. Therefore, significant energy saving and space saving (miniaturization) can be achieved as compared with the conventional process, and the economic effect is extremely high.

Further, NOx adsorbed on the adsorbent is easily desorbed by heating, so that the adsorbent can be easily regenerated. Therefore, the adsorbent according to the present invention can be suitably used as an adsorbent for a rotary NOx adsorption rotor that continuously repeats adsorption and desorption (regeneration) of NOx.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an adsorbent having a multilayer structure of a flat plate and a corrugated plate.

FIG. 2 is a graph showing a relationship between time and a breakthrough rate.

FIG. 3 is a graph showing the relationship between time and breakthrough rate.

FIG. 4 is a graph showing a relationship between time and a breakthrough rate.

FIG. 5 is a graph showing the relationship between time, NOx concentration, and temperature.

FIG. 6 is a graph showing the relationship between time, NOx concentration, and temperature.

FIG. 7 is a graph showing a relationship between time and a breakthrough rate.

FIG. 8 is a graph showing the relationship between the amount of Ru supported and the 10% breakthrough time.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Takanobu Watanabe, 5-28 Nishikujo, Konohana-ku, Osaka-shi Inside Tachibana Shipbuilding Co., Ltd. (72) Atsushi Fukuju, 5-3-1 Nishikujo, Konohana-ku, Osaka-shi No. 28 Inside Tate Shipbuilding Co., Ltd. (72) Inventor Masaki Akiyama 5-3-28 Nishikujo, Konohana-ku, Osaka-shi Inside Nachidate Shipbuilding Co., Ltd. Yuki Nishira 5-3-1 Nishikujo, Konohana-ku, Osaka-shi No. 28 Sun Tachibai Shipbuilding Co., Ltd.

Claims (1)

(57) [Claims] 1. A ceramic paper carrier holding anatase titania is selected from the group consisting of ruthenium halides, potassium, sodium, magnesium, calcium, manganese, copper, zinc, rubidium, zirconium, barium, cerium and molybdenum. A low-concentration nitrogen oxide adsorption / removal agent, wherein the at least one metal halide is co-supported.