JP2002248348A - Adsorbing agent for nitrogen oxide and/or sulfur oxide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adsorbing agent for nitrogen oxide and/or sulfur oxide, a method of removing nitrogen oxide and/or sulfur oxide using the adsorbing agent and a method of regenerating the adsorbing agent. SOLUTION: The adsorbing agent for nitrogen oxide and/or sulfur oxide contains 2-valent iron.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an adsorbent for nitrogen oxides and / or sulfur oxides, a method for removing nitrogen oxides and / or sulfur oxides using the adsorbent, and a method for regenerating the adsorbent. .

[0002]

2. Description of the Related Art With respect to a method of removing nitrogen oxides from a fixed nitrogen oxide source such as a boiler, conventionally, ammonia has been selectively reduced by using ammonia as a reducing agent to remove harmless nitrogen. The catalytic reduction method of converting to water is widely used as the most economical method.

On the other hand, it is included in ventilation gas or air in road tunnels, roads with shelters, deep underground spaces, road intersections, underground parking lots, etc., and gas discharged from combustion equipment used in homes. The concentration of nitrogen oxides is about 5 ppm, which is significantly lower than the concentration of nitrogen oxides in boiler exhaust gas, and the gas temperature is room temperature, and the amount of gas is enormous. In order to efficiently remove nitrogen oxides by applying the above-described catalytic reduction method to a conventional ammonia reduction method, for example, a ventilation gas for a road tunnel, the temperature of the ventilation gas needs to be 300 ° C. or higher, As a result, a large amount of energy is required, and there is an economical problem in applying the above catalytic reduction method as it is.

[0004] Under such circumstances, the above-described ammonia reduction method cannot be directly used, and nitrogen oxide is efficiently removed from exhaust gas having a low nitrogen oxide concentration, for example, 5 ppm or less, such as ventilation gas for road tunnels. It is desired. Therefore, a method of adsorbing and removing a low concentration of nitrogen oxides by an adsorbent and an adsorbent suitable for the method have been proposed.

[0005] The present applicant has proposed an adsorbent suitable for adsorbing and removing nitrogen oxides from the above-mentioned low-concentration nitrogen oxide-containing gas (JP-A-10-128105, JP-A-10-105105). 192498, JP-A-10-309435
JP-A-11-28351, JP-A-11-2835
No. 2, JP-A-2000-51655, JP-A-2000-2
25318, Japanese Patent Application No. 2000-325780, and Japanese Patent Application No. 2000-06651). In addition, the applicant has
As a method for efficiently removing nitrogen oxides from gases containing sulfur oxides in addition to nitrogen oxides, remove sulfur oxides in advance and then contact them with a nitrogen oxide adsorbent to adsorb and remove nitrogen oxides (Japanese Patent Laid-Open No. 10-76136). Further, the present applicant has also proposed a method of regenerating an adsorbent whose performance has been reduced by use in the presence of a reducing agent by heating the adsorbent (JP-A-2000-2253).
No. 17).

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a low concentration nitrogen oxide and / or sulfur oxide suitable for adsorbing and removing nitrogen oxides and / or sulfur oxides, in particular, having a low concentration of about 5 ppm or less. An object of the present invention is to provide an adsorbent suitable for adsorption and removal, a method for removing nitrogen oxides and / or sulfur oxides using the adsorbent, and a method for regenerating the adsorbent.

[0007]

Means for Solving the Problems As a result of intensive studies, the present inventors have found that the following adsorbents can solve the above problems, and have completed the present invention based on this finding.
The present invention relates to a nitrogen oxide and / or sulfur oxide adsorbent as a first invention, a nitrogen oxide and / or sulfur oxide removal method using the adsorbent as a second invention, and the adsorption as a third invention It is a method of regenerating the agent. Hereinafter, description will be made in order.

[0008] That is, the first invention is a nitrogen oxide and / or sulfur oxide adsorbent (i) containing ferrous iron. The adsorbent (i) includes alkali metal elements, copper, titanium, silicon, zirconium, alkaline earth metal elements, platinum, gold, ruthenium, rhodium,
It is preferable to contain at least one element selected from palladium and cobalt. More preferably, it is as follows.

First, the adsorbent (i) is a nitrogen oxide and / or sulfur oxide adsorbent (ii) characterized by further containing an alkali metal element and / or copper.

The adsorbent (i) or (ii)
Is an adsorbent (iii) for nitrogen oxides and / or sulfur oxides, further containing at least one element selected from titanium, silicon, zirconium and alkaline earth metal elements.

The adsorbents (i) to (iii) further include platinum, gold, ruthenium, rhodium, palladium, manganese, nickel, cobalt, zinc, vanadium, niobium,
Nitrogen oxides and / or sulfur containing at least one element selected from chromium, molybdenum and tungsten, preferably at least one element selected from platinum, gold, ruthenium, rhodium, palladium and cobalt An oxide adsorbent (iv). The adsorbents (i) to (iv) can be used separately or simultaneously as adsorbents.

The adsorbent of the present invention is obtained by preparing an adsorbent precursor containing an iron component in advance and subjecting the precursor to a heat treatment in a reducing atmosphere to obtain a nitrogen oxide and / or nitrogen oxide.
Or a sulfur oxide adsorbent.

[0013] A second invention is characterized in that a nitrogen oxide and / or sulfur oxide is removed by contacting a gas containing nitrogen oxide and / or sulfur oxide with the adsorbent. And / or a method for removing sulfur oxides.

[0014] A third invention relates to a method for regenerating a nitrogen oxide and / or sulfur oxide adsorbent, which comprises heating the adsorbent in the presence of a reducing agent when regenerating the adsorbent. is there.

Further, the present invention provides a method for removing nitrogen oxides or nitrogen oxides and sulfur oxides by contacting a gas containing nitrogen oxides or nitrogen oxides and sulfur oxides with the adsorbent. Heating the adsorbent in the presence of a reducing agent to desorb the adsorbed nitrogen oxides and subjecting the desorbed nitrogen oxides to denitration treatment; or nitrogen oxides or nitrogen oxides and sulfur oxides This is a method for regenerating an adsorbent.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The adsorbent of the present invention is for adsorbing a low concentration of nitrogen oxides and / or sulfur oxides of 5 ppm or less. This nitrogen oxide is shown as NOx, and specifically includes NO and NO2. The sulfur oxide is represented by SOx, and specifically includes SO2. The adsorbent of the present invention can treat nitrogen oxides and sulfur oxides simultaneously or separately, but is particularly excellent in adsorbing and removing NO2.

First, the adsorbent according to the first invention will be described. The iron may be in any state as long as the adsorbent contains divalent iron (i). Preferably, at least a part of the iron exists in a divalent form.

The total amount of the iron component (hereinafter also referred to as (A)) does not need to be in a divalent form, but is contained only in an amount effective to adsorb nitrogen oxides and / or sulfur oxides. It just needs to be. Among them, those contained in the form of Fe3O4 are preferred. Fe3O4 is Fe _II FeIII2O4 of inverse spinel, it is known that at least part of the iron with a divalent form.
(For example, 880 pages of Chemical Dictionary, Tokyo Chemical Industry, 1989) That is, Fe3O4 is included as one type of iron compound having a divalent form. The fact that the iron component has a divalent form can be confirmed by measuring the lattice spacing (d value) by X-ray diffraction. FeO d
The values are 2.15 ± 0.01, 2.49 ± 0.01 and 1.
52 ± 0.01, and the d value of Fe 3 O 4 is 2.5
3 ± 0.01, 1.48 ± 0.01 and 2.97 ± 0.0
There is one.

The preparation method is not particularly limited, and it can be prepared by various methods. For example, it may be prepared using a commercially available or previously prepared divalent iron compound. Above all, as described below, an adsorbent in which an adsorbent precursor containing an iron component is prepared in advance, and this precursor is heat-treated in a reducing atmosphere to convert at least a part of iron into a divalent form Is preferred. As a starting material of the component (A),
Iron oxides, hydroxides, nitrates, sulfates, halides, organic metal salts, and organic acid salts such as acetates and oxalates can be used.

Preferably, the adsorbent further contains an alkali metal element and / or copper (adsorbent (i
i)). Alkali metal element (hereinafter also referred to as (B))
By adding, the deterioration with time of the nitrogen oxide and / or sulfur oxide removal performance is suppressed, and the durability is improved. Further, by adding copper (hereinafter also referred to as (C)), the efficiency of removing nitrogen oxides and / or sulfur oxides is improved. That is, a more preferred embodiment of the present invention is an adsorbent in which at least a part of the iron component is in a divalent form and further contains an alkali metal element and copper.

The form of the alkali metal element of the component (B) is not particularly limited, and may be any form as long as it can adsorb nitrogen oxides and / or sulfur oxides as an adsorbent. For example, it is contained in the form of a hydroxide, carbonate or bicarbonate. As starting materials for the component (B), hydroxides, carbonates, bicarbonates,
In addition to nitrates and nitrites, organic acid salts such as acetate, oxalate, citrate and sorbate can be used.

The form of the copper component (C) may be any form as long as it has the above-mentioned effects, and among them, at least a part thereof has zero or monovalent valence. Is preferred. That is, it is preferable that at least a part of copper has zero valence or monovalent valence.
Specifically, (a) substantially all of the copper has zero valence,
(B) substantially all of the copper is monovalent; (c) some of the copper is zero-valent and the remainder is monovalent; (d) some of the copper is zero-valent and the remainder is two And (e) copper having a part of copper having zero valence and a balance of monovalent and divalent copper. Copper does not necessarily need to be all 0-valent or 1-valent, and it is sufficient that the effective amount to obtain the effect of the present invention is 0-valent or 1-valent. Whether the copper component has a zero-valent or monovalent form can be confirmed by measuring the lattice spacing (d value) by X-ray diffraction, similarly to the iron component. The d value of Cu (0 valence) is 2.09 ± 0.0
1, 1.81 ± 0.01 and 1.28 ± 0.01, and the d value of Cu 2 O (monovalent) is 2.47 ± 0.01, 2.14 ± 0.01 and 1.51 ±. 0.01.

The preparation method is not particularly limited, and it can be prepared by various methods. Above all, as described later, an adsorbent precursor containing iron and an alkali metal element and / or copper is prepared in advance, and this precursor is heat-treated in a reducing atmosphere to convert at least a part of iron into divalent iron. Is preferred. When a copper component is contained, the heat treatment in the reducing atmosphere described above converts at least a part of iron into a divalent form and at the same time converts at least a part of copper into zero or monovalent adsorption. Agents are preferred. As a starting material of the component (C), copper oxides, hydroxides, carbonates, nitrates, sulfates, halides, organic metal salts, and organic acid salts such as acetates and oxalates may be used. it can.

The adsorbent (i) or (ii) further contains at least one element selected from titanium, silicon, zirconium and alkaline earth metal elements (hereinafter also referred to as component (D)). (Adsorbent (ii
i)). There is no particular limitation on the form of component (D),
Any form may be used as long as the function of adsorbing nitrogen oxides and / or sulfur oxides is obtained. For example, they are contained as oxides, composite oxides, hydroxides, carbonates, phosphates, sulfates, and the like. Among components (D), zirconium and alkaline earth metals are preferably used in that an adsorbent having excellent durability can be obtained. As the starting materials, oxides, hydroxides, carbonates, sulfates, halides, phosphates and the like of each element can be used.

The adsorbent of the present invention further comprises platinum as component (E) and adsorbents (i) to (iii).
At least one element selected from gold, ruthenium, rhodium, palladium, manganese, nickel, cobalt, zinc, vanadium, niobium, chromium, molybdenum and tungsten, preferably selected from platinum, gold, ruthenium, rhodium, palladium and cobalt It can contain at least one element (adsorbent (i
v)).

Hereinafter, the adsorbent according to the present invention will be described in detail. However, it is not limited to the specific adsorbent as long as it is a component according to the present invention. can do. The adsorbent of the present invention is not particularly limited as long as it contains divalent iron, but typical examples include the following. As for the ratio, the components (A), (B), (C) and (D) are converted to oxides. Specifically, for example, iron is converted to Fe2O3, potassium is converted to K2O, and calcium is converted to CaO. . <Adsorbent 1> (A) iron and (B) an alkali metal element (L
adsorbent containing i, Na, K, Rb, Cs).

Regarding the ratio of each component, component (A)
0 to 99% by mass, preferably 80 to 99% by mass;
Component (B) is 1 to 30% by mass, preferably 1 to 20% by mass (total 100% by mass, the same applies hereinafter). <Adsorbent 2> An adsorbent containing (A) iron and (C) copper.

Regarding the ratio of each component, component (A) is 1
The content is from 1 to 99% by mass, preferably from 5 to 95% by mass, and the component (C) is from 1 to 99% by mass, preferably from 5 to 95% by mass. <Adsorbent 3> An adsorbent containing (A) iron, (B) an alkali metal element, and (C) copper. Regarding the ratio of each component, component (A) is 1 to 98% by mass, preferably 5 to 98% by mass.
Component (B) is 1 to 30% by mass, preferably 1 to 20% by mass, and component (C) is 1 to 98% by mass, preferably 1 to 94% by mass. <Adsorbent 4> (A) iron and (D) titanium, silicon, zirconium and alkaline earth metal elements (Be, Mg,
An adsorbent containing at least one element selected from Ca, Sr, and Ba).

Regarding the ratio of each component, component (A) is 1
The content of the component (D) is 10 to 99% by mass, preferably 15 to 95% by mass. <Adsorbent 5> An adsorbent containing (A) iron, (B) an alkali metal element, and (D) at least one element selected from titanium, silicon, zirconium, and alkaline earth metal elements.

Regarding the ratio of each component, component (A) is 1
The component (B) is 1 to 30% by mass, preferably 1 to 20% by mass, and the component (D) is 10 to 98% by mass, preferably 14% by mass.
９４94% by mass. <Adsorbent 6> (A) iron, (C) copper and (D) titanium,
An adsorbent containing at least one element selected from silicon, zirconium and alkaline earth metal elements.

About the ratio of each component. Component (A) is 1
The component (C) is 1 to 89% by weight, preferably 1 to 81% by weight, and the component (D) is 10 to 98% by weight, preferably 14 to 85% by weight.
９４94% by mass. <Adsorbent 7> (A) iron, (B) alkali metal element,
An adsorbent containing (C) copper and (D) at least one element selected from titanium, silicon, zirconium and alkaline earth metal elements.

What is the ratio of each component? Component (A) is 1
The component (B) is 1 to 30% by weight, preferably 1 to 20% by weight, and the component (C) is 1 to 89% by weight, preferably 1 to 85% by weight. ~ 8
1% by mass, and the component (D) is 9 to 97% by mass, preferably 13 to 93% by mass.

Among the above adsorbents, adsorbents 5 and 7
Is preferred. Specifically, an adsorbent containing components (A), (B) and (D), and an adsorbent containing components (A), (B), (C) and (D) It is.

The adsorbent of the present invention further comprises, as component (E), platinum as the adsorbent (i) to (iii).
At least one element selected from gold, ruthenium, rhodium, palladium, manganese, nickel, cobalt, zinc, vanadium, niobium, chromium, molybdenum and tungsten, preferably selected from platinum, gold, ruthenium, rhodium, palladium and cobalt It can contain at least one element (adsorbent (i
v)). In the adsorbents 1 to 7, the ratio of the component (E) is 0.0% as metal conversion in the case of platinum, gold, ruthenium, rhodium and palladium with respect to the total amount of each component.
1-10 mass%, preferably 0.05-5 mass% can be added. In the case of manganese, nickel, cobalt, zinc, vanadium, niobium, chromium, molybdenum and tungsten, 0.5 to 30% by mass, preferably 1 to 20% by mass as oxides can be added.
The form of the component (E) is contained, for example, as a metal, an oxide, a composite oxide, or the like. Among the components (E),
Preferably, platinum, gold, ruthenium, rhodium, palladium and cobalt are used, more preferably ruthenium and cobalt. Starting materials for component (E) include oxides, hydroxides, nitrates, sulfates,
Carbonates, halides, organic metal salts, ammonium complexes and the like can be used.

The adsorbent containing ferrous iron can be prepared by various methods as described above, and any adsorbent having divalent iron in the adsorbent may be used. An adsorbent obtained by preparing an adsorbent precursor containing an iron component and subjecting the precursor to heat treatment in a reducing atmosphere to convert at least a part of iron into a divalent form.

Similarly, when the composition further contains an alkali metal element and / or copper, the adsorbent can be prepared by various methods, or the composition contains an iron component, an alkali metal element component and / or a copper component in advance. An adsorbent obtained by preparing an adsorbent precursor and subjecting the precursor to a heat treatment in a reducing atmosphere to convert at least a part of iron into a divalent form is preferable. If the copper component is contained, the effect of the present invention is obtained, but at least a part of iron is converted to a divalent form by the heat treatment under the reducing atmosphere, and at least a part of the copper is converted to zero-valent or Adsorbents converted to monovalent are preferred.

The "adsorbent precursor" may be any one which has the composition of the above-mentioned adsorbents (1) to (7) and can be made into the adsorbent according to the present invention by various treatments. Those containing in the form of a trivalent iron compound, preferably diiron trioxide (Fe2O3), are preferred.

The above adsorbent precursor can be prepared by a method generally used for preparing this kind of adsorbent. A typical preparation method of the adsorbent precursor containing the components (A), (B), (C) and (D) will be described below, but the present invention is not limited thereto. Not something.

Component (A), component (B) and component (C)
An aqueous solution or powder of the starting material is added to the component (D) together with a commonly used molding aid, and mixed and stirred.
Mold with an extruder. The obtained molded body is 50 to 120
After drying at 200 ° C., 200-600 ° C., preferably 250
Calcination is carried out at 500 ° C. for 1 to 10 hours, preferably 2 to 6 hours, in the air or in an inert gas such as nitrogen. Note that the last baking step is not essential and can be omitted as appropriate.

Alternatively, a molded article containing at least one of the components (A) to (C) and the component (D) may be prepared in advance, and the molded article may be impregnated with the remaining components. For example, after a molded body composed of the components (A), (C) and (D) is prepared as described above, the component (B) is impregnated and supported.

The preferred adsorbent of the present invention can be obtained by subjecting the above adsorbent precursor to heat treatment in a reducing atmosphere.
Heat treatment in a reducing atmosphere refers to a method in which a reducing agent is added to the atmosphere gas of the heat treatment and the heating treatment is performed in the presence of the reducing agent, and a substance having a reducing action is previously carried in an adsorbent precursor. Then, heat treatment is performed in an inert gas.
In the present invention, when the alkali metal element is carried in the form of its organic acid salt in the adsorbent precursor containing the alkali metal element, the adsorbent precursor is heat-treated in an inert gas. Thus, a suitable adsorbent of the present invention can be obtained. In addition, even when the alkali metal element is contained as the organic acid salt, a suitable adsorbent of the present invention can be obtained by a method of adding a reducing agent to the atmosphere gas of the heat treatment.

Therefore, first, a method of adding a reducing agent to the atmosphere gas of the heat treatment and performing the heat treatment in the presence of the reducing agent will be described. The reducing agent means hydrogen and a combustible organic compound. Examples of the combustible organic compound include hydrocarbons, preferably saturated or unsaturated hydrocarbons having 1 to 4 carbon atoms. In the present invention, hydrogen or hydrocarbons, particularly hydrogen, is suitably used as the reducing agent. Representative examples of the hydrocarbons include saturated or unsaturated hydrocarbons such as methane, ethane, propane, butane, ethylene, propylene, and butadiene.

The reducing agent is usually diluted with another gas and used as a mixed gas with an inert gas such as nitrogen. Specifically, when hydrogen is used as the reducing agent, it is used as a mixed gas of hydrogen and an inert gas such as nitrogen or helium. The concentration of hydrogen in the mixed gas is usually 0.1 to 20% by volume, preferably 0.5 to 1% by volume.
0% by volume. Although a mixed gas with air can be used, there is a danger of explosion. Therefore, it is generally preferable to use the mixed gas with the inert gas as described above. Even in the case of a combustible organic compound, it is used as a mixed gas with an inert gas such as nitrogen. The concentration of the combustible organic compound in the mixed gas is usually from 0.001 to 1% by volume, preferably from 0.01 to 0.5% by volume.

Examples of the gas that can be used for diluting the reducing agent include the above-mentioned inert gas such as nitrogen and helium and air, as well as water vapor (H 2 O) and carbon dioxide gas. Thus, typical examples of the mixed gas include a combination of hydrogen and an inert gas, and a combination of a combustible organic compound and an inert gas.

The heating temperature is usually from 200 to 600 ° C., preferably from 300 to 500 ° C., more preferably from 30 to 500 ° C.
0-400 ° C. The adsorbent precursor is usually at room temperature, but the rate of temperature increase up to the heating temperature is not particularly limited and can be determined as appropriate. The heating time cannot be specified unconditionally, but can be appropriately selected usually in the range of 30 minutes to 10 hours, preferably 30 minutes to 5 hours.

The heat treatment of the present invention is preferably performed under ventilation of a reducing agent. In the case where the heat treatment is performed under ventilation of the reducing agent, the degree of ventilation is not particularly limited, and the condition may be such that a new reducing agent is supplied.

Next, a method for heat-treating an adsorbent precursor containing an alkali metal element in the form of an organic acid salt in an inert gas when the alkali metal element is contained will be described. The adsorbent precursor is prepared, for example, by preparing a molded body composed of the component (A), the component (C) and the component (D) as described above, and then adding an alkali metal organic acid salt as the component (B). It is obtained by being impregnated and supported. Representative examples of the alkali metal organic acid salt include potassium acetate, tripotassium citrate, potassium sorbate and the like. Among them, potassium acetate is preferably used. Usually, nitrogen is used as the inert gas. The heating conditions are the same as in the case of the heat treatment in the presence of the reducing agent.

It is not clear why the heat treatment in the above-mentioned inert gas causes the reduction to proceed. For example, in the case of iron oxide (trivalent), the alkali metal organic acid salt is thermally decomposed by the heat treatment. It is considered that the oxygen held by the iron oxide is consumed during the thermal decomposition, and the iron oxide is reduced. The present invention is not limited by such theoretical considerations.

The shape of the adsorbent of the present invention is not particularly limited, and can be appropriately selected from a column, a cylinder, a sphere, a plate, a honeycomb, and other integrally molded products. For this molding, a general molding method, for example, tablet molding, extrusion molding or the like can be used. In the case of a spherical shape, the average particle size is usually 1 to 10 mm. In the case of a honeycomb-shaped adsorbent, it is the same as a so-called monolith carrier, and can be manufactured by an extrusion molding method, a method of winding a sheet-shaped element, or the like. The shape of the gas passage port (cell shape) may be any of a hexagon, a quadrangle, a triangle, or a corrugation. Cell density (number of cells /
The unit sectional area is usually 25 to 800 cells / square inch (× 2.54 cm), and preferably 25 to 500 cells / square inch (× 2.54 cm).

According to the method of the present invention, a gas containing nitrogen oxides and / or sulfur oxides is brought into contact with the adsorbent to adsorb the nitrogen oxides and / or sulfur oxides and purify the gas. A typical example of the above-mentioned gas is a ventilation gas or an atmospheric gas from the above-mentioned road tunnel or the like.
It is suitably used for removing nitrogen oxides and sulfur oxides from gases having a low concentration of pm or less.

The method for contacting the gas with the adsorbent is not particularly limited, and is usually carried out by introducing a gas into a layer made of the adsorbent. Since the treatment conditions differ depending on the properties of the gas to be treated and the like, they cannot be specified unconditionally, but for example, the temperature of the gas supplied to the adsorbent layer is usually
The temperature is 0 to 100 ° C, and particularly preferably 0 to 50 ° C. The space velocity (SV) of the gas supplied to the adsorbent layer
Is usually 500 to 50,000 / h (STP),
The range of 2000 to 30000 / h (STP) is preferable.

The regeneration according to the present invention is to regenerate an adsorbent having reduced adsorption power by adsorbing nitrogen oxides and / or sulfur oxides. For example, ventilation gas or air in a road tunnel or the like usually contains nitrogen oxides and sulfur oxides. Therefore, the adsorbent used in such places includes nitrogen oxides and sulfur oxides. Although the adsorption force is reduced by the adsorption, according to the present invention, the nitrogen oxides adsorbed in this manner can be efficiently desorbed.

The reducing agent used in the regeneration treatment of the present invention means hydrogen and a combustible organic compound. Representative examples of the combustible organic compound include hydrocarbons, preferably having 1 carbon atom.
To 4 saturated or unsaturated hydrocarbons, or oxygen-containing organic compounds, specifically fatty acids, alcohols and aldehydes, preferably lower fatty acids having 1 to 4 carbon atoms, and 1 to 4 carbon atoms. Examples thereof include lower alcohols and lower aldehydes having 1 to 4 carbon atoms. Among these, saturated or unsaturated hydrocarbons having 1 to 4 carbon atoms and lower fatty acids are preferably used. The flammable organic compounds can be used alone or in combination of two or more. In the present invention, hydrogen, a saturated or unsaturated hydrocarbon having 1 to 4 carbon atoms or a lower fatty acid, particularly hydrogen is suitably used as a reducing agent.

Representative examples of the above hydrocarbons include saturated or unsaturated hydrocarbons such as methane, ethane, propane, butane, ethylene, propylene and butadiene. Representative examples of the lower fatty acids include mono- or di-, such as formic acid, acetic acid, propionic acid, butyric acid, oxalic acid, malonic acid, succinic acid, tartaric acid, malic acid, acrylic acid, methacrylic acid, and maleic acid.
Alternatively, a saturated or unsaturated carboxylic acid can be used.

The above reducing agent is usually diluted with another gas and used as a mixed gas with an inert gas such as nitrogen. Specifically, when hydrogen is used as the reducing agent, it is used as a mixed gas of hydrogen and an inert gas such as nitrogen or helium. The hydrogen concentration in this mixed gas is usually 0.1 to 20% by volume, preferably 0.5 to 1% by volume.
0% by volume. Note that a gas mixture with air can be used outside the explosion range, but it is generally preferable to use a gas mixture with an inert gas as described above. Even in the case of a combustible organic compound, it is used as a mixed gas with an inert gas such as nitrogen. The concentration of the combustible organic compound in the mixed gas is usually 0.001 to 1% by volume,
Preferably it is 0.01 to 0.5% by volume. When the combustible organic compound is a solid, it may be dissolved in water, sprayed as an aqueous solution, and supplied.

Examples of the gas that can be used for diluting the reducing agent include the above-mentioned inert gas such as nitrogen and helium and air, as well as water vapor (H 2 O) and carbon dioxide gas. Thus, typical examples of the mixed gas include a combination of hydrogen and an inert gas, and a combination of a combustible organic compound and an inert gas.

According to the present invention, the regenerating process can be performed at a heating temperature of 600 ° C. or less. The heating temperature is usually from 200 to 600 ° C, preferably from 30 to
The temperature is 0 to 500C, more preferably 300 to 450C. The adsorbent to be regenerated is usually at room temperature,
The rate of temperature rise up to the heating temperature is not particularly limited and can be appropriately determined.

Although the heating time varies depending on the degree of adsorption of nitrogen oxides, the heating temperature, etc., it cannot be specified unconditionally.
Usually, it can be appropriately selected within a range of 30 minutes to 10 hours, preferably 30 minutes to 5 hours.

The regeneration treatment of the present invention is preferably performed under ventilation of a reducing agent. When the regeneration process is performed under ventilation of the reducing agent, there is no particular limitation on the degree of ventilation, and the condition may be such that a new reducing agent is supplied. In general, a reducing agent may be introduced into the device (adsorbent layer) filled with the adsorbent from the inlet side, and may be circulated to the outlet side.

The adsorbent regenerated by the regeneration treatment of the present invention can be reused for adsorption and removal of nitrogen oxides and / or sulfur oxides.

During the regeneration treatment of the adsorbent, a gas (exhaust gas) containing desorbed nitrogen oxides is generated. After removing the nitrogen oxides in the exhaust gas to make them harmless, they are released into the atmosphere. Is preferred. The method for removing nitrogen oxides from the exhaust gas, that is, the method for denitration is not particularly limited, and can be performed by a conventionally known denitration method. Specifically, for example, ammonia may be added to the exhaust gas as a reducing agent and contacted with a denitration catalyst to reduce nitrogen oxides to nitrogen and water.

When purifying a gas by efficiently removing nitrogen oxides from a gas containing sulfur oxides in addition to nitrogen oxides, the sulfur oxides are removed in advance, and the gas is then brought into contact with the adsorbent of the present invention. By adsorbing and removing nitrogen oxides, the durability of the adsorbent is improved, and nitrogen oxides can be effectively removed over a long period of time.

The method for removing the sulfur oxide is not particularly limited, and a method of removing the gas by washing with water, a method of bringing the gas into contact with an adsorbent for adsorbing the sulfur oxide, and the like can be used. Above all, a method using an adsorbent for sulfur oxides is preferably used from the viewpoint of a compact apparatus and low energy consumption.

As the sulfur oxide adsorbent, SOx
Any adsorbent may be used as long as it can adsorb, and among them, an adsorbent containing at least one selected from activated carbon, transition metals, alkali metals and alkaline earth metals is suitably used. Representative examples of transition metals include Ni, Co,
Examples include Fe, Mn, Cr, Mo, W, V, Nb, Zn, and Cu. Representative examples of alkali metals and alkaline earth metals include Li, Na, and K, respectively.
And Mg, Ca, Ba. There is no particular limitation on the form of these elements in the adsorbent.
Any form may be used as long as it can adsorb x. Specific examples include oxides, carbonates, sulfates, chlorides and hydroxides.

The adsorbent for sulfur oxides may be used as a carrier
Alkaline earth metal salts, alumina, silica, titania, zirconia, silica-alumina, alumina-zirconia,
It may contain at least one of silica-titania, silica-zirconia and titania-zirconia.

Thus, in a preferred embodiment of the present invention, a gas containing nitrogen oxides and sulfur oxides is first contacted with an adsorbent for sulfur oxides to adsorb and remove sulfur oxides, and then the adsorbent of the present invention To purify the gas by adsorbing and removing nitrogen oxides. Thereby, the durability of the adsorbent of the present invention is improved.

[0067]

The adsorbent of the present invention comprises nitrogen oxides and / or
Or, it has high adsorption performance to sulfur oxides, particularly low concentration nitrogen oxides and / or sulfur oxides, and shows excellent durability.

[0068]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. Example 1 To 1,000 g of iron oxalate dihydrate was added potassium acetate 75
g of water dissolved in 100 g of water was added, and the mixture was well mixed with a kneader while further adding an appropriate amount of water, and then molded into a pellet having a diameter of 5 mm and a length of 5 mm with an extruder. Further, after drying the pellets at 100 ° C. for 10 hours, the pellets were fired at 600 ° C. for 3 hours in a nitrogen atmosphere to obtain an adsorbent (1).

The composition of the adsorbent (1) thus obtained was Fe: K (as Fe 2 O 3: K 2 O) = 92.
5: 7.5 (% by mass). FIG. 1 shows the X-ray diffraction of the adsorbent (1). FIG. 1 shows that the adsorbent (1) contains FeO. Example 2 An appropriate amount of water was added to 1,000 g of α-FeO (OH) and mixed well with a kneader.
m, and molded into a pellet having a length of 5 mm. The pellet was dried at 100 ° C. for 10 hours, and then fired at 500 ° C. for 3 hours in an air atmosphere. Further, the pellets are 4N-
After impregnating in an aqueous potassium acetate solution for 2 minutes,
After drying for an hour, a pellet-shaped adsorbent precursor was obtained. The composition of this precursor is Fe: K (as Fe2O3: K2O)
= 92.5: 7.5 (% by mass).

Next, the pellets were subjected to a heat treatment (reduction treatment with an organic acid salt) at 400 ° C. for 2 hours in a nitrogen atmosphere to obtain an adsorbent (2). FIG. 2 shows the X-ray diffraction of the adsorbent (2). FIG. 2 shows that the adsorbent (2) contains Fe3O4. Example 3 723.3 g of α-FeO (OH), basic copper carbonate (manufactured by Nippon Chemical Industry Co., Ltd., containing 50% by mass of copper metal)
After adding an appropriate amount of water to 4 g and mixing well with a kneader, the mixture was formed into a pellet having a diameter of 5 mm and a length of 5 mm by an extruder. The pellet was dried at 100 ° C. for 10 hours, and then calcined at 500 ° C. for 3 hours in an air atmosphere to obtain a pellet-shaped adsorbent precursor. The composition of this precursor is F
e: Cu (as Fe2O3: CuO) = 70.3: 2
9.7 (% by mass).

Next, the pellets were subjected to a heat treatment (reduction treatment with a reducing agent) at 400 ° C. for 2 hours under a flow of hydrogen / nitrogen (5/95% by volume) to obtain an adsorbent (3). Example 4 723.3 g of α-FeO (OH), basic copper carbonate (manufactured by Nippon Chemical Industry Co., Ltd., containing 50% by mass of copper metal)
After adding an appropriate amount of water to 4 g and mixing well with a kneader, the mixture was formed into a pellet having a diameter of 5 mm and a length of 5 mm by an extruder. The pellet was dried at 100 ° C. for 10 hours, and then fired at 500 ° C. for 3 hours in an air atmosphere. Further, the pellet was impregnated with a 4N-potassium acetate aqueous solution for 2 minutes, and then dried at 120 ° C. for 5 hours to obtain a pellet-shaped adsorbent precursor. The composition of this precursor is Fe: Cu:
K (as Fe2O3: CuO: K2O) = 65.0:
27.5: 7.5 (% by mass).

Next, the pellet was heated at 400 ° C. for 2 hours in a nitrogen atmosphere to obtain an adsorbent (4).
FIG. 3 shows the X-ray diffraction of the adsorbent (4). FIG. 3 shows that the adsorbent (4) contains Fe3O4 and zero-valent copper. Example 5 α-FeO (OH) 222.6 g, basic copper carbonate (manufactured by Nippon Chemical Industry Co., Ltd., containing 50% by mass of copper metal)
6 g, 600 g of calcium carbonate, and after mixing well with a kneader while adding an appropriate amount of water, a diameter of 5 mm was obtained with an extruder.
It was molded into a pellet having a length of 5 mm. This pellet is
After drying at 00 ° C. for 10 hours, it was calcined at 500 ° C. for 3 hours in an air atmosphere to obtain an adsorbent precursor. The composition of this precursor is Fe: Cu: Ca (Fe2O3: CuO: CaO
As) = 29.2: 21.9: 48.9 (% by mass).

Next, the pellet was heated at 400 ° C. for 2 hours under a flow of hydrogen / nitrogen (5/95% by volume) to obtain an adsorbent (5). FIG. 4 shows the X-ray diffraction of the adsorbent (5). From FIG. 4, the adsorbent (5) is Fe3O4 and 0
It can be seen that it contains copper of valence. Example 6 222.6 g of α-FeO (OH), 75 of calcium carbonate
After mixing well with a kneader while adding an appropriate amount of water to 0 g, the mixture was molded into a pellet having a diameter of 5 mm and a length of 5 mm using an extruder. The pellet was dried at 100 ° C. for 10 hours, and then fired at 500 ° C. for 3 hours in an air atmosphere. Further, after impregnating the pellets with a 4N-potassium carbonate aqueous solution for 2 minutes, the pellets were dried at 120 ° C. for 5 hours to obtain a pellet-shaped adsorbent precursor. The composition of this precursor is Fe: Ca:
K (as Fe2O3: CaO: K2O) = 29.8:
62.7: 7.5 (% by mass).

Next, the pellet was heated at 400 ° C. for 2 hours under a flow of hydrogen / nitrogen (5/95% by volume) to obtain an adsorbent (6). FIG. 5 shows the X-ray diffraction of the adsorbent (6). FIG. 5 shows that the adsorbent (6) contains Fe3O4. Example 7 A pellet-shaped adsorbent precursor was obtained in the same manner as in Example 6, except that an aqueous 4N-potassium acetate solution was used instead of the aqueous 4N-potassium carbonate solution. The composition of this precursor is Fe: Ca: K (Fe2O3: CaO: K
= 29.8: 62.7: 7.5 (% by mass)
Met.

Next, the pellet was heated at 400 ° C. for 2 hours in a nitrogen atmosphere to obtain an adsorbent (7). Example 8 Aqueous ammonia (NH3, 25) was added to 400 L (liter) of water.
%) 286 L, and add Snowtex NCS-
30 (silica sol manufactured by Nissan Chemical Co., Ltd .;
24% by mass). 153 L of an aqueous solution of titanyl sulfate in sulfuric acid (containing 250 g / L as TiO2; total sulfuric acid concentration 1,100 g / L) was added to the obtained solution.
L and diluted with titanium-containing sulfuric acid aqueous solution
It was added slowly to obtain a coprecipitated gel. In addition, 15
After leaving it for a time, a TiO2-SiO2 gel was obtained. The gel was filtered, washed with water, and dried at 200 ° C. for 10 hours.
Next, the powder was fired in an air atmosphere at 600 ° C. for 6 hours, further pulverized using a hammer mill, and classified by a classifier to obtain a powder having an average particle diameter of 10 μm. The resulting powder (hereinafter referred to as TS
-1) was Ti: Si = 4: 1 (atomic ratio).

An adsorbent precursor was prepared in the same manner as in Example 7 except that the above-mentioned TS-1 was used in place of calcium carbonate in Example 7, and then heat-treated in the same manner as in Example 7. The pellets of the adsorbent (8) having the composition shown in the following were obtained. Examples 9 to 10 Except that titanium oxide and zirconium oxide were used in place of calcium carbonate in Example 7, an adsorbent precursor was prepared in the same manner as in Example 7, and further heat-treated in the same manner as in Example 7. Adsorbents (9) to (10) having compositions shown in Table 1
Was obtained. Example 11 1.5 g of ruthenium oxide (manufactured by Tanaka Kikinzoku Co., Ltd., containing 65% by mass of ruthenium metal), iron oxalate dihydrate 45
0.9 g and 750 g of calcium carbonate were mixed well with a kneader while adding an appropriate amount of water.
m, and molded into a pellet having a length of 5 mm. The pellet was dried at 100 ° C. for 10 hours, and then fired at 500 ° C. for 3 hours in an air atmosphere. Further, the pellets are 4N-
After impregnating in an aqueous potassium acetate solution for 2 minutes,
After drying for an hour, a pellet-shaped adsorbent precursor was obtained. The composition of this precursor is Ru: Fe: Ca: K (Ru: Fe2O
3: As CaO: K2O) = 0.1: 29.8: 6
2.6: 7.5 (% by mass).

Next, the pellets were heated at 400 ° C. for 2 hours under a nitrogen atmosphere to obtain an adsorbent (11). Examples 12 to 15 An adsorbent having the composition shown in Table 1 in the same manner as in Example 11 except that an aqueous solution of platinum nitrate, an aqueous solution of gold hydrochloride, an aqueous solution of rhodium nitrate, and an aqueous solution of palladium nitrate were used in place of ruthenium oxide in Example 11 The pellets of 12) to (15) were obtained. Example 16 222.6 g of α-FeO (OH), basic copper carbonate (manufactured by Nippon Chemical Industry Co., Ltd., containing 50% by mass of copper metal)
6 g, 600 g of calcium carbonate, and after mixing well with a kneader while adding an appropriate amount of water, a diameter of 5 mm was obtained with an extruder.
It was molded into a pellet having a length of 5 mm. This pellet is
After drying at 00 ° C. for 10 hours, baking was performed at 500 ° C. for 3 hours in an air atmosphere. Further, the pellet was impregnated with a 4N-potassium acetate aqueous solution for 2 minutes, and then dried at 120 ° C. for 5 hours to obtain a pellet-shaped adsorbent precursor. The composition of this precursor is Fe: Cu: Ca: K (Fe2O3: Cu
O: CaO: K2O) = 27.2: 20.4: 4
5.6: 6.8 (% by mass).

Next, the pellet was heated at 400 ° C. for 2 hours under a nitrogen atmosphere to obtain an adsorbent (16). FIG. 6 shows the X-ray diffraction of the adsorbent (16). FIG. 6 shows that the adsorbent (16) contains Fe3O4 and zero-valent copper. Example 17 1.5 g of ruthenium oxide (manufactured by Tanaka Kikinzoku Co., Ltd., containing 65% by mass of ruthenium metal), α-FeO (OH) 22
2.6 g, basic copper carbonate (manufactured by Nippon Chemical Industry Co., Ltd., containing 50% by mass of copper metal) 239.6 g, calcium carbonate 6
After adding an appropriate amount of water to 00 g and mixing well with a kneader, the mixture was formed into a pellet having a diameter of 5 mm and a length of 5 mm by an extruder. The pellet was dried at 100 ° C. for 10 hours, and then fired at 500 ° C. for 3 hours in an air atmosphere. Further, the pellet was impregnated with a 4N-potassium acetate aqueous solution for 2 minutes, and then dried at 120 ° C. for 5 hours to obtain a pellet-shaped adsorbent precursor. The composition of this precursor is Ru: Fe:
Cu: Ca: K (Ru: Fe2O3: CuO: CaO:
= 0.1: 27.1: 20.4: 45.
6: 6.8 (% by mass).

Next, the pellet was heated at 400 ° C. for 2 hours in a nitrogen atmosphere to obtain an adsorbent (17). Example 18 α-FeO (OH) 222.6 g, basic copper carbonate (manufactured by Nippon Chemical Industry Co., Ltd., containing 50% by mass of copper metal)
6 g, cobalt carbonate 74.1 g, calcium carbonate 550
After mixing well with a kneader while adding an appropriate amount of water to g,
It was formed into a pellet having a diameter of 5 mm and a length of 5 mm by an extruder. The pellet was dried at 100 ° C. for 10 hours, and then fired at 500 ° C. for 3 hours in an air atmosphere. Further, the pellet was impregnated with a 4N-potassium acetate aqueous solution for 2 minutes, and then dried at 120 ° C. for 5 hours to obtain a pellet-shaped adsorbent precursor. The composition of this precursor is Fe: Cu:
Co: Ca: K (Fe2O3: CuO: Co3O4: C
aO: as K2O) = 26.4: 19.8: 6.6:
40.6: 6.6 (% by mass).

Next, the pellet was heated at 400 ° C. for 2 hours under a nitrogen atmosphere to obtain an adsorbent (18). Comparative Example 1 An adsorbent having a composition shown in Table 1 (Comparative Example 1) in the same manner as in Example 2 except that the heat treatment was performed in air instead of the final heat treatment under a nitrogen atmosphere. Was obtained. Comparative Example 2 An adsorbent having the composition shown in Table 1 (Comparative Example 2) was prepared in the same manner as in Example 5 except that the heat treatment was not performed under the flow of hydrogen / nitrogen (5/95% by volume). The pellet of 2) was obtained. The X-ray diffraction of the adsorbent of Comparative Example 2 is shown in FIG.
Shown in From FIG. 7, the adsorbents (Comparative 2) are FeO and Fe
It turns out that it does not contain 3O4. In addition, it can be seen that neither zero-valent nor monovalent copper is contained. Comparative Example 3 An adsorbent having a composition shown in Table 1 (Comparative Example 3) was prepared in the same manner as in Example 6 except that the heat treatment was not performed under the flow of hydrogen / nitrogen (5/95% by volume). The pellet of 3) was obtained. The X-ray diffraction of the adsorbent of Comparative Example 3 is shown in FIG.
Shown in From FIG. 8, the adsorbent (Comparative 2) is FeO and Fe
It turns out that it does not contain 3O4. Comparative Examples 4 and 5 Adsorption of the compositions shown in Table 1 in the same manner as in Examples 16 and 17, except that the heat treatment was performed in air instead of the final heat treatment in a nitrogen atmosphere in Examples 16 and 17. Pellets of the agents (Comparative 4) and (Comparative 5) were obtained. In addition,
X-ray diffraction of the adsorbent of Comparative Example 4 is shown in FIG. 9 as a representative example.
FIG. 9 shows that the adsorbent (Comparative 4) does not contain FeO and Fe3O4. In addition, it can be seen that neither zero-valent nor monovalent copper is contained.

The adsorbents (1) to (10) obtained as described above
Table 1 summarizes the compositions of (18) and the comparative adsorbents (Comparative 1) to (Comparative 5).

In Table 1, components A, B, C, D
Is an oxide and E is a metal conversion (however, cobalt is an oxide conversion). Example 19 Adsorbents (1) to (5), and a comparative adsorbent (Comparative 1),
The nitrogen oxide adsorption ability and sulfur oxide adsorption ability of (Comparative 2) were evaluated by the following methods. (Evaluation method (1)) 35 ml of an adsorbent was filled into a glass reaction tube having an inner diameter of 30 mm. A synthesis gas (A) having the following composition was introduced into the adsorbent layer under the following conditions. Synthesis gas (A) composition Nitric oxide (NO): 0.9 ppm, nitrogen dioxide (NO)
2): 0.1 ppm, sulfur dioxide (SO2): 0.05
ppm, H2O: 1.9% by volume, remaining: air Processing conditions Gas amount: 17.3 NL / min, processing temperature: 25 ° C, space velocity (SV): 30,000 / h (STP), gas humidity: 60% RH One hour after the introduction of the syngas, nitrogen dioxide (NO) in the syngas at the inlet and the outlet of the adsorbent layer
2) The concentration was measured by a chemiluminescent NOX meter and the sulfur oxide (SO2) concentration was measured by an ultraviolet absorption SO2 meter, and the NO2 and SO2 removal rates were calculated according to the following equation. NO2 removal rate (%) = {(NO2 concentration at inlet-NO2 at outlet)
Concentration) / (inlet NO2 concentration) × 100 SO2 removal rate (%) = {(inlet SO2 concentration−outlet SO2
Concentration) / (inlet SO2 concentration)} × 100 One hour after the introduction of the syngas (A), nitrogen dioxide (N2) in the syngas at the inlet and outlet of the adsorbent layer
O2) concentration and sulfur oxide (SO2) concentration are measured,
The NO2 and SO2 removal rates were calculated. Table 2 shows the results of the evaluation test. Example 20 Adsorbents (6) to (18) and Comparative Adsorbent (Comparative 3)
The nitrogen oxide-adsorbing ability and the sulfur oxide-adsorbing ability of (Comparative 5) were evaluated by the following methods. (Evaluation method (2)) After measuring the nitrogen oxide adsorbing ability and sulfur oxide adsorbing ability of each adsorbent in the same manner as the evaluation method (1), the gas composition was changed and the following accelerated durability test was performed. Was. <Accelerated durability test> A synthesis gas (B) having the following composition was introduced into this adsorbent layer under the following conditions. Synthesis gas (B) composition Nitric oxide (NO): 2.7 ppm, nitrogen dioxide (NO
2): 0.3 ppm, sulfur dioxide (SO2): 0.15
ppm, H2O: 1.9% by volume, remaining: air Processing conditions Gas amount: 17.3 NL / min, processing temperature: 25 ° C, space velocity (SV): 30,000 / h (STP), gas humidity: 60% RH After the accelerated durability test was performed for 200 hours, one hour after the introduction of the synthesis gas (A), one hour after the introduction of the synthesis gas, the nitrogen dioxide (NO2) concentration and the sulfur oxide ( The SO2) concentration was measured in the same manner as in the evaluation method (1), and the NO2 and SO2 removal rates were calculated. Table 3 shows the results of the evaluation test. Example 21 A regeneration test was performed using the adsorbent (6) after the accelerated durability test in Example 20, and the nitrogen oxide adsorption ability and the sulfur oxide adsorption ability after the regeneration were evaluated by the following methods. <Regeneration Test> A regeneration gas having the following composition was introduced into each adsorbent after the accelerated durability test under the following conditions. Regenerating gas composition Hydrogen: 5% by volume, remaining nitrogen Processing conditions Gas amount: 1.7 NL / min, Temperature rising rate: 250 ° C./h
r, treatment temperature: 400 ° C., treatment time: 1 hour After performing the above regeneration, the mixture was cooled to room temperature, and evaluated (1).
The nitrogen oxide adsorbing ability and the sulfur oxide adsorbing ability of the adsorbent were measured in the same manner as described above, and the adsorbing ability of the adsorbent after regeneration was evaluated. Table 4 shows the results. Examples 22 and 23 Example 2 was the same as Example 21 except that the adsorbent (16) and the adsorbent (18) were used instead of the adsorbent (6).
In the same manner as in Example 1, the nitrogen oxide adsorbing ability and the sulfur oxide adsorbing ability were evaluated. Table 4 shows the results.

From the results in Tables 3 and 4, it can be seen that the adsorption performance has been recovered after the regeneration. Example 24 (Preparation of adsorbent for sulfur oxide) TS obtained in Example 8
-1 After kneading well with a kneader while adding an appropriate amount of water to 1,000 g of powder, 5 mm in diameter and 5 mm in length by an extruder.
Into pellets. This pellet is heated at 100 ° C for 1 hour.
After drying for 0 hour, it was baked at 350 ° C. for 3 hours in an air atmosphere. Further, the pellet was impregnated with a 6N-sodium carbonate aqueous solution for 2 minutes, and then dried at 120 ° C. for 5 hours. The composition of the adsorbent for sulfur oxides obtained in this manner has TS-1: Na (as TS-1: Na2O) = 7.
6.1: 23.9 (% by mass). (Evaluation method) In the evaluation method (2) of Example 20, the adsorbent for sulfur oxide was added to the gas flow in a stage preceding the gas flow.
ml, and the adsorbent (11) obtained in Example 11
Except for l filling, the nitrogen oxide adsorbing ability and the sulfur oxide adsorbing ability were evaluated in the same manner as in the evaluation method (2). Table 5 shows the results.

From the results shown in Tables 3 and 5, it can be seen that the durability performance of the adsorbent (11) is improved by installing the adsorbent for sulfur oxide in the former stage. Examples 25 and 26 In the evaluation method of Example 24, the adsorbents (16) and (1) obtained in Examples 16 and 17 were used as subsequent adsorbents.
The nitrogen oxide adsorbing ability and the sulfur oxide adsorbing ability were evaluated in the same manner as in Example 24 except that 7) was used. Table 5 shows the results.

From the results in Tables 3 and 5, it can be seen that the durability performance of the adsorbents (16) and (17) is improved by installing the adsorbent for sulfur oxide in the former stage.

[0086]

[Table 1]

[0087]

[Table 2]

[0088]

[Table 3]

[0089]

[Table 4]

[0090]

[Table 5]

[0091]

[Brief description of the drawings]

FIG. 1 is an X-ray diffraction diagram of an adsorbent (1).

FIG. 2 is an X-ray diffraction diagram of adsorbent (2).

FIG. 3 is an X-ray diffraction diagram of an adsorbent (4).

FIG. 4 is an X-ray diffraction diagram of the adsorbent (5).

FIG. 5 is an X-ray diffraction diagram of the adsorbent (6).

FIG. 6 is an X-ray diffraction diagram of the adsorbent (16).

FIG. 7 is an X-ray diffraction diagram for a comparative adsorbent (Comparative 2).

FIG. 8 is an X-ray diffraction diagram of a comparative adsorbent (Comparative 3).

FIG. 9 is an X-ray diffraction diagram of a comparative adsorbent (Comparative 4).

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B01J 20/30 B01D 53/34 132Z 20/34 F-term (Reference) 4D002 AA02 AA12 AB01 BA04 DA01 DA04 DA11 DA21 DA22 DA23 DA25 EA02 4G066 AA13B AA15B AA16B AA22B AA23B AA27B AA28B CA23 CA28 FA17 FA21 GA01 GA06

Claims (8)

[Claims] 1. An adsorbent for nitrogen oxides and / or sulfur oxides, which contains ferrous iron. 2. The adsorbent according to claim 1, wherein the adsorbent further contains an alkali metal element and / or copper. 3. The adsorbent according to claim 1, further comprising titanium,
3. The adsorbent according to claim 1, comprising at least one element selected from the group consisting of silicon, zirconium and alkaline earth metal elements. 4. The adsorbent according to claim 1, further comprising at least one element selected from platinum, gold, ruthenium, rhodium, palladium and cobalt. The adsorbent as described. 5. The adsorbent according to claim 1, wherein the adsorbent is obtained by heat-treating a precursor of the adsorbent in a reducing atmosphere. . 6. A method comprising contacting a gas containing nitrogen oxides and / or sulfur oxides with the adsorbent according to claim 1 to remove nitrogen oxides and / or sulfur oxides. A method for removing nitrogen oxides and / or sulfur oxides. 7. A method for regenerating the adsorbent according to claim 1, wherein the adsorbent is heated in the presence of a reducing agent. Playback method. 8. A nitrogen oxide or a gas containing nitrogen oxide and sulfur oxide is brought into contact with the adsorbent according to any one of claims 1 to 5, and nitrogen oxide or nitrogen oxide and sulfur oxide are oxidized. After removing the substances, the adsorbent is heated in the presence of a reducing agent to desorb the adsorbed nitrogen oxides, and the desorbed nitrogen oxides are denitrated. A method for regenerating an oxide and sulfur oxide adsorbent.