JP2022009583A - Oxygen excess type metal oxide, manufacturing method and recycling method therefor, oxygen condensation device and oxygen adsorption and desorption device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel oxygen excess type metal oxide excellent in oxygen adsorption and desorption speed and a manufacturing method therefor, and a method for recycling oxygen adsorption and desorption performance of the oxygen excess type metal oxide or the like.

SOLUTION: There is provided oxygen excess type metal oxide having stoichiometry represented by the following general formula (1) and total of desorption amount of carbon dioxide at from room temperature to 1000°C by a temperature rising desorption method at temperature rising rate of 40°C/min of less than 450 μmol/g. A_jD_kE_mG_nO_7+δ (1), where A is one or more kind selected from a group consisting of trivalent rare earth element and Ca, D is one or more kind selected from an alkali earth metal element, E and G are each independently one or more kind selected from oxygen tetrahedrally coordinated element and at least one of them is a transition metal element, j>0, k>0 and each independently m≥0, n≥0 and j+k+m+n=6, 0<δ≤1.5.

SELECTED DRAWING: Figure 1

COPYRIGHT: (C)2022,JPO&INPIT

Description

The present invention relates to an oxygen-rich metal oxide, a method for producing the same and a method for regenerating it, and an oxygen concentrator and an oxygen desorption device.

Conventionally, in a wide range of technical fields such as fuel cells and three-way catalysts for exhaust gas purification devices, there has been a demand for the development of materials capable of adsorbing and desorbing oxygen by changing the temperature. As such a material, metal oxides (ceramic materials) such as ZrO ₂ -CeO ₂ (CZ), Bi ₄ V ₂ O ₁₁ (BIMEDOX), YBa ₂ Cu ₃ O _{6 + δ} (Y-123) are known. There is.

As such a metal oxide, an oxygen-excessive metal oxide represented by the general formula _{AjBkCmDnO7 + δ such as YBaCo 4 O 7 + δ is used in a} low temperature range of 500 ° C. or lower, particularly 200 to 200. It has a remarkable thermal weight change characteristic of rapidly absorbing a large amount of oxygen at 400 ° C and releasing oxygen when the temperature rises, which has the performance suitable as ceramics for high-performance oxygen storage or oxygen selective film. It has been reported (see Patent Document 1). Further, it has been reported that this oxygen-rich metal oxide causes a phase change during the absorption and desorption of oxygen (see Non-Patent Document 1).

International Publication No. 2007/004684

O. Chmaissem et al., J. Solid State Chem. 181, 664 (2008)

The present inventors have further studied and searched for factors that affect the oxygen absorption / desorption ability of the above-mentioned oxygen-excessive metal oxide. Then, they have found that when the amount of CO ₂ adsorbed is large, there is a problem that the oxygen adsorption / desorption rate is greatly reduced in the oxygen adsorption / desorption ability.

The present invention has been made in view of the above problems. That is, an object of the present invention is to provide a novel oxygen-excessive metal oxide having an excellent oxygen absorption / desorption rate and a method for producing the same. Another object of the present invention is to provide a novel oxygen concentrator, an oxygen absorption / desorption device, and the like using the above-mentioned oxygen-excessive metal oxide. Furthermore, another object of the present invention is to provide a method for regenerating the oxygen adsorption / desorption ability of an oxygen-rich metal oxide.

The present inventors have diligently studied to solve the above problems. As a result, although it has the same stoichiometry and crystal structure as the conventional oxygen-rich metal oxide represented by the _above -mentioned general formula _{AjBkCmDnO7 + δ} , it has a high _degree of oxygen desorption. We have found a factor that gives superiority or inferiority to (Tolerance), and have found that the above-mentioned problems can be solved by using an oxygen-excessive metal oxide having a small amount of carbon dioxide adsorbed, and have reached the present invention.

That is, the present invention provides the specific embodiments shown in the following (1) to (20).
(1) The following general formula (1):
A _j D _k E _m G _n O _{7 + δ}・ ・ ・ (1)
(During the ceremony,
A is one or more selected from the group consisting of trivalent rare earth elements and Ca.
D is one or more selected from alkaline earth metal elements, and is
E and G are each independently selected from one or more of the oxygen 4-coordinating elements, and at least one is a transition metal element.
j> 0 and k> 0, respectively, and m ≧ 0 and n ≧ 0, respectively, where j + k + m + n = 6 and 0 <δ ≦ 1.5. )
It has a stoichiometry represented by, and the total amount of carbon dioxide desorbed from room temperature to 1000 ° C. in the temperature desorption method at a heating rate of 40 ° C./min is less than 450 μmol / g. Type metal oxide.

(2) The oxygen-rich metal oxide according to (1) above, wherein A in the general formula (1) contains Y.
(3) The oxygen-rich metal oxide according to (1) or (2) above, wherein D in the general formula (1) contains Ba.
(4) The oxygen-rich metal oxide according to any one of (1) to (3) above, wherein E in the general formula (1) contains Co.

(5) In powder X-ray diffraction measurement, it has a _LuBa (Zn, Al) _4O7 type crystal structure characterized by a diffraction pattern having all of the following (a) to (d).
(A) 110 peaks (b) 103 peaks (c) 112 peaks (d) 201 peaks Desorption amount of carbon dioxide from room temperature to 1000 ° C. in the temperature rise desorption method at a heating rate of 40 ° C./min. Oxygen excess type metal oxide having a total of less than 450 μmol / g.
The oxygen-rich metal oxide according to any one of (1) to (5) above is a precursor of the oxygen-rich metal oxide having an oxygen partial pressure of 10 kPa or less, 700 ° C. or higher, and 950 ° C. It is preferably obtained by heat treatment with a carbon dioxide concentration of less than 0.01 vol% in the atmosphere gas in the furnace immediately before the start of temperature lowering.

(6) An oxygen absorption / desorption device using the oxygen-excessive metal oxide according to any one of (1) to (5) above.
(7) The oxygen absorption / desorption device according to (6) above, wherein oxygen is adsorbed on the oxygen-excessive metal oxide at a temperature lower than 350 ° C. and oxygen is released from the oxygen-excessive metal oxide at 350 ° C. or higher.
(8) At 200 ° C. or higher and 400 ° C. or lower, oxygen is adsorbed on the oxygen-rich metal oxide in the presence of oxygen, and oxygen is discharged from the oxygen-rich metal oxide under a pressure at which the oxygen partial pressure is lower than that at the time of oxygen adsorption. Release,
The oxygen absorption / desorption device according to (6) above.
(9) Using the oxygen-excessive metal oxide according to any one of (1) to (5) above, oxygen is adsorbed on the oxygen-excessive metal oxide at less than 350 ° C., and the oxygen-excessive metal oxide is adsorbed at 350 ° C. or higher. An oxygen concentrator that concentrates oxygen by releasing oxygen from an oxygen-rich metal oxide.
(10) Using the oxygen-rich metal oxide according to any one of (1) to (5) above, oxygen is added to the oxygen-rich metal oxide in the presence of oxygen at 200 ° C. or higher and 400 ° C. or lower. An oxygen concentrator that concentrates oxygen by adsorbing and releasing oxygen from the oxygen-excessive metal oxide under a pressure whose oxygen partial pressure is lower than that at the time of oxygen adsorption.

(11) Oxygen storage / separation / concentration, which comprises the oxygen-rich metal oxide according to any one of (1) to (5) above, and is characterized by storing, separating and / or concentrating oxygen. Device.
(12) An oxidation reaction apparatus comprising the oxygen-rich metal oxide according to any one of (1) to (5) above, wherein an oxidation reaction is carried out using stored oxygen.
(13) The oxygen-excessive metal oxide according to any one of (1) to (5) above is provided, and heating is performed using the heat generated by storage, separation and / or concentration of oxygen. A heating device.
(14) The oxygen-excessive metal oxide according to any one of (1) to (5) above is provided, and cooling is performed using cold heat generated by storage, separation and / or concentration of oxygen. A cooling device.
(15) The oxygen-excessive metal oxide according to any one of (1) to (5) above is provided, and heat exchange is performed using hot and / or cold heat generated by storage, separation and / or concentration of oxygen. A heat exchanger, characterized in that it does.

(16) The oxygen-excessive metal oxide having stoichiometry represented by the general formula (1) is evacuated to 10 kPa or less, 700 ° C. or higher, less than 950 ° C., in the atmosphere gas in the furnace immediately before the start of temperature lowering. A method for producing an oxygen-rich metal oxide, which comprises heat-treating with a carbon dioxide concentration of less than 0.01 vol%.
(17) A feature of obtaining an oxygen-excessive metal oxide in which the total amount of carbon dioxide desorbed from room temperature to 1000 ° C. in the temperature rise desorption method at a heating rate of 40 ° C./min is 450 μmol / g or more. The method for producing an oxygen-rich metal oxide according to (16) above.

Further, in one aspect of the present invention, it is possible to prevent performance deterioration due to continued use of the oxygen-rich metal oxide as a catalyst. In that case, one aspect of the present invention is defined as a method for regenerating the catalyst. Specifically, it is as shown in (18) below.
(18) The following general formula (1):
A _j D _k E _m G _n O _{7 + δ}・ ・ ・ (1)
(In the formula, A is one or more selected from the group consisting of trivalent rare earth elements and Ca.
D is one or more selected from alkaline earth metal elements, and is
E and G are each independently selected from one or more of the oxygen 4-coordinating elements, and at least one is a transition metal element.
j> 0 and k> 0, respectively, and m ≧ 0 and n ≧ 0, respectively, where j + k + m + n = 6 and 0 <δ ≦ 1.5. )
A method for regenerating an oxygen-rich metal oxide, which comprises heating an oxygen-rich metal oxide having stoichiometry represented by (1) at an oxygen partial pressure of 10 kPa or less, 400 ° C. or higher, and lower than 950 ° C.

The present invention can also be defined as the embodiments shown in (19) and (20) below.
(19) Y, Ba and Co are contained at least in a stoichiometric ratio of 0.8 to 1.2: 0.8 to 1.2: 3.2 to 4.8.
In powder X-ray diffraction measurement, it has a _LuBa (Zn, Al) _4O7 type crystal structure characterized by a diffraction pattern having all of the following (a) to (d).
(A) 110 peaks (b) 103 peaks (c) 112 peaks (d) 201 peaks Desorption amount of carbon dioxide from room temperature to 1000 ° C. in the temperature rise desorption method at a heating rate of 40 ° C./min. Oxygen excess type metal oxide having a total of less than 450 μmol / g.
(20) The following general formula (1):
A _j D _k E _m G _n O _{7 + δ}・ ・ ・ (1)
(During the ceremony,
A is one or more selected from the group consisting of trivalent rare earth elements and Ca.
D is one or more selected from alkaline earth metal elements, and is
E and G are each independently selected from one or more of the oxygen 4-coordinating elements, and at least one is a transition metal element.
j> 0 and k> 0, respectively, and m ≧ 0 and n ≧ 0, respectively, where j + k + m + n = 6 and 0 <δ ≦ 1.5. ), And the oxygen-rich metal oxide produced by the method according to (16) above.

The oxygen-rich metal oxide of each of the above aspects of the present invention exhibits an abnormal thermal weight change in a low temperature region when the temperature or oxygen partial pressure is moved up and down in a temperature range of 500 ° C. or lower. According to the findings of the present inventors, it has been clarified that the abnormal change in thermogravimetric analysis is due to the above-mentioned change in oxygen indefinite ratio (indefinite ratio amount: δ). That is, the oxygen-rich metal oxide of each of the above embodiments of the present invention typically rapidly adsorbs a large amount of oxygen below 350 ° C., and rapidly adsorbs a large amount of oxygen in a high temperature region of about 350 to 400 ° C. Is released. Further, at 200 ° C. or higher and 400 ° C. or lower, a large amount of oxygen is adsorbed in the presence of oxygen with an oxygen partial pressure of 0 kPa or more, and a large amount of oxygen is rapidly released under a pressure whose oxygen partial pressure is lower than that at the time of oxygen adsorption.

Moreover, surprisingly, the oxygen-rich metal oxide of each of the above-mentioned embodiments of the present invention has an excellent property that the oxygen absorption / desorption rate is very high as compared with the oxygen-rich metal oxide having a large amount of CO ₂ adsorption. Was found to have.

That is, the oxygen-rich metal oxide of each of the above-mentioned aspects of the present invention _is the same as the _above -mentioned general oxygen-rich metal oxide represented by the conventionally known general formula _{AjBkCmDnO7 + δ} . In addition to having the stoichiometry represented by the formula (1), the total amount of carbon dioxide desorbed from room temperature to 1000 ° C. in the temperature desorption method at a heating rate of 40 ° C./min is 450 μmol / min. One characteristic is that it is less than g.

Compared with the one in which the total amount of desorbed carbon dioxide is 450 μmol / g or more, the oxygen-rich metal oxide of each of the above-mentioned embodiments of the present invention shows almost no difference in the maximum adsorption capacity of oxygen, but oxygen. The absorption / desorption speed is high, and there is no decrease in the maximum oxygen adsorption capacity within a unit time due to repeated absorption / desorption in a short time, and the oxygen extraction capacity within a unit time, which is important for practical use, is excellent. , Found by the findings of the present inventors. It is known that the surface of an alkaline earth metal oxide is basic and CO ₂ which is an oxidizing gas is easily adsorbed, and the same phenomenon occurs on the surface of an oxide containing an alkaline earth metal element. It is presumed that it is. CO ₂ adsorbed on the surface often forms carbonate, and it is presumed that it inhibits the absorption and release of oxygen. However, the action is not limited to these.

The oxygen-rich metal oxide of the present invention having such an amount of carbon dioxide desorption is a precursor of an oxygen-rich metal oxide having a stoichiometry represented by the general formula (I) from various raw materials. It can be easily obtained by heat treatment at a partial pressure of 10 kPa or less, 700 ° C. or higher, less than 950 ° C., and a carbon dioxide concentration in the atmosphere gas in the furnace immediately before the start of temperature reduction of less than 0.01 vol%. Further, an oxygen-rich metal oxide having a stoichiometry represented by the general formula (I), particularly a stoichiometry represented by the general formula (I) having a total desorption amount of carbon dioxide of 450 μmol / g or more. The oxygen-rich metal oxide having an oxygen excess can be easily regenerated by heat-treating it at an oxygen partial pressure of 10 kPa or less and at 400 ° C. or higher and lower than 950 ° C. At this time, it is particularly effective when the total amount of carbon dioxide desorbed from room temperature to 1000 ° C. in the temperature raising desorption method at a heating rate of 40 ° C./min is 450 μmol / g or more, but less than that. Even if there is, the influence of carbon dioxide adsorption can be further reduced. Therefore, the amount of carbon dioxide desorbed is not a limiting factor in the method for producing or regenerating an oxygen-rich metal oxide. However, from the viewpoint of increasing the effect of the obtained oxygen-rich metal oxide, it is preferable that the amount of carbon dioxide desorbed from the oxygen-rich metal oxide is 450 μmol / g or more.

According to the present invention, it is possible to provide a novel oxygen-excessive metal oxide having an excellent oxygen absorption / desorption rate and a method for producing the same. More specifically, since it is possible to provide an oxygen-excessive metal oxide having a high oxygen absorption / desorption rate, a practical ceramic material for oxygen storage or oxygen selection is realized. Moreover, according to the present invention, since the oxygen absorption / desorption ability of the oxygen-excessive metal oxide can be easily regenerated, the oxygen-excessive metal oxide can be extended in life and economically improved in particular. .. Further, according to the present invention, it is possible to provide a practical manufacturing method capable of increasing the oxygen adsorption / desorption rate of an oxygen-excessive metal oxide having a low oxygen adsorption / desorption rate. Then, by using the oxygen-rich metal oxide of the present invention, it is possible to provide an oxygen concentrator, an oxygen absorption / desorption device, and the like having excellent practical performance.

It is a figure which shows the result of the powder X-ray-diffraction measurement of the oxygen excess type metal oxide of Comparative Example 1, and Examples 1, 2 and 3. It is a figure which shows the oxygen adsorption amount and the oxygen desorption rate of the oxygen excess type metal oxide of the comparative example 1. FIG. It is a figure which shows the oxygen adsorption amount and the oxygen desorption rate of the oxygen excess type metal oxide of Example 1. FIG. It is a figure which shows the oxygen desorption amount and the oxygen desorption rate of the oxygen excess type metal oxide of Example 2. FIG. It is a figure which shows the oxygen desorption amount and the oxygen desorption rate of the oxygen excess type metal oxide of Example 3. FIG. It is a figure which shows the cycle characteristic of oxygen absorption / desorption of the oxygen excess type metal oxide of the comparative example 1. FIG. It is a figure which shows the cycle characteristic of oxygen absorption / desorption of the oxygen excess type metal oxide of Example 1. FIG. It is a figure which shows the cycle characteristic of oxygen absorption desorption of the oxygen excess type metal oxide of Example 2. It is a figure which shows the cycle characteristic of the oxygen absorption and desorption of the oxygen excess type metal oxide of Example 3. FIG.

Hereinafter, embodiments of the present invention will be described in detail, but the following embodiments are examples for explaining the present invention, and the present invention is not limited thereto and does not deviate from the gist thereof. It can be changed arbitrarily within the range.

The oxygen-rich metal oxide of the present embodiment has a stoichiometry represented by the following general formula (1), and has a temperature rise rate of 40 ° C./min to 1000 ° C. from room temperature in the temperature rise desorption method. The total amount of carbon dioxide desorbed in the water is less than 450 μmol / g.
A _j D _k E _m G _n O _{7 + δ}・ ・ ・ (1)
(During the ceremony,
A is one or more selected from the group consisting of trivalent rare earth elements and Ca.
D is one or more selected from alkaline earth metal elements, and is
E and G are each independently selected from one or more of the oxygen 4-coordinating elements, and at least one is a transition metal element.
j> 0 and k> 0, respectively, and m ≧ 0 and n ≧ 0, respectively, where j + k + m + n = 6 and 0 <δ ≦ 1.5. )

Here, in the present specification, "having stoichiometry" represented by the above general formula (1) means that each element A, D, E represented in the above general formula (1) is stoichiometrically. Even if G and O are contained at least in the ratio shown in the above general formula (1), and elements other than these A, D, E, G and O (hereinafter, also simply referred to as “other elements”) are further contained. It means good. That is, the oxygen-rich metal oxide of the present embodiment may contain other elements as unavoidable impurities or as arbitrary compounding components in addition to the elements represented by the above general formula (1).

In the above general formula (1), A is one or more selected from the group consisting of trivalent rare earth elements and divalent Ca. Examples of the trivalent rare earth element include Sc, Y and lanthanoids having atomic numbers 57 to 71, and among these, Y is preferable. Further, since a plurality of elements can be dissolved in the site (A site) occupied by A, it is preferable that A is two kinds of Y and Ca, and further, A is composed of three or more kinds of elements. May be. Here, A preferably contains Y in an amount of 50 mol% or more, more preferably 80 mol% or more, and further preferably 90 mol% or more. Although the upper limit of the content ratio of Y is not particularly limited, A preferably contains Y in an amount of 100 mol% or less, more preferably 99.9 mol% or less, and further preferably 99.5 mol% or less.

In the above general formula (1), D is one or more selected from alkaline earth metal elements. Examples of the alkaline earth metal element include Sr and Ba. In this specification, Ca corresponds to A in the above general formula (1) and does not correspond to D. Here, D preferably contains Ba or Sr. Further, since a plurality of elements can be dissolved in the site (D site) occupied by D, it is preferable that D is two kinds of Ba and Sr, and further, D is composed of three or more kinds of elements. It may have been. Here, D preferably contains Ba in an amount of 50 mol% or more, more preferably 80 mol% or more, and further preferably 90 mol% or more. Although the upper limit of the content ratio of Ba is not particularly limited, D preferably contains Ba in an amount of 100 mol% or less, more preferably 99.9 mol% or less, and further preferably 99.5 mol% or less.

E and G are one or more elements independently selected from the four-coordinated elements of oxygen, that is, the four-coordinated oxygen elements. In the present specification, the oxygen 4-coordinating element means "an element in which four oxygen atoms are coordinated or bonded", and the same applies to the following. Here, E and G are treated as not being the same element. The oxygen 4-coordinating element is not particularly limited, but Co, Fe, Zn, Al and the like are preferable. Further, at least one of E and G is a transition metal element. Here, E preferably contains Co. Further, based on the total of E and G, it is preferable that Co is contained in an amount of 50 mol% or more, more preferably 75 mol% or more, still more preferably 87.5 mol% or more. Although the upper limit of the content ratio of Co is not particularly limited, it is preferable that Co is contained in an amount of 100 mol% or less, more preferably 99.9 mol% or less, still more preferably 99.5, based on the total of E and G. It is less than mol%.

In the above general formula (1), j, k, m and n are values standardized with the total of these as 6. That is, when j + k + m + n = 6, each independently has j> 0, k> 0, m ≧ 0, and n ≧ 0. Here, 1.2> j> 0.8 is preferable, and 1.1> j> 0.9 is more preferable. Further, 1.2> k> 0.8 is preferable, and 1.1> k> 0.9 is more preferable. Further, 4.8 ≧ m + n ≧ 3.2 is preferable, and 4.4 ≧ m + n ≧ 3.6 is more preferable. Further, n may be 0, in which case 4.8 ≧ m ≧ 3.2 is preferable, and 4.4 ≧ m ≧ 3.6 is more preferable.

In the above general formula (1), the non-stoichiometric amount δ is preferably 0 <δ ≦ 1.5, more preferably 0 <δ ≦ 1.4, and further preferably 0 <δ ≦ 1.25. ..

Specific examples of the oxygen-rich metal oxide of the present embodiment are not particularly limited, but include YBaCo ₄ O _{7.0 + δ} , ScBaCo ₄ O _{7.0 + δ} , YSrCo ₄ O _{7.0 + δ} , ScSrCo ₄ O _{7.0 + δ} , and the like. Can be mentioned. In addition, the compounds listed in Tables 2 and 3 of page 254 of M. Valldor, Solid State Sciences 6,251 (2004), such as LuBaCo ₄ O _{7.0 + δ} , YbBaCo ₄ O _{7.0 + δ} , TmBaCo ₄ O _7. Examples thereof include _{0 + δ} , ErBaCo ₄ O _{7.0 + δ} , HoBaCo ₄ O _{7.0 + δ} , DyBaCo ₄ O _{7.0 + δ} , and the above-exemplified compounds in which Ba is replaced with Sr. Specific element combinations include YBaCo ₃ ZnO _{7.0 + δ} , YBaCo ₂ Zn ₂ O _{7.0 + δ} , YBaCo Zn ₃ O _{7.0 + δ} , YBaCo ₃ FeO _{7.0 + δ} , YBaZn ₃ FeO _{7.0 + δ} , and the like. .. Further, among these compounds, Y is replaced with Sc, Ba is replaced with Sr, or Y is replaced with Sc and Ba is replaced with Sr. Other examples of specific element combinations include CaBaZn ₂ Fe ₂ O _{7.0 + δ} , CaBaZn ₂ FeAlO _{7.0 + δ} , CaBaCo ₂ ZnAlO 7.0 + _δ , CaBaCoZn ₂ AlO _{7.0 + δ} , CaBaCo ₃ AlO _{7.0 + δ} . CaBaCo ₃ FeO _{7.0 + δ} , CaBaCo ₂ ZnFeO _{7.0 + δ} , CaBaCoZn ₂ FeO _{7.0 + δ} , CaBaCo ₂ Fe ₂ O _{7.0 + δ} , CaBaCoZnFe ₂ O 7.0 + δ, CaBaCo _{ZnFe 2} O _{7.0 + δ} , CaBaCo ₃ ZnO _7.2 O _{7.0 + δ} and the like can be mentioned. Further, among these compounds, those in which Ba is replaced with Sr can also be mentioned.

In the present embodiment, the stoichiometry of the oxygen-rich metal oxide can be measured by, for example, an ICP (Inductively coupled plasma) emission spectrometry method, a redox titration method such as an iodine titration method, or the like. It goes without saying that oxygen is preferably measured after being annealed in an inert gas because some deadsorption occurs depending on the production conditions, the standing time in the atmosphere and its temperature.

The feature of this embodiment is that the amount of carbon dioxide adsorbed by the oxygen-rich metal oxide itself is small. The amount of carbon dioxide adsorbed can be identified by measuring the amount of carbon dioxide desorbed by the thermal desorption method. This oxygen-excessive metal oxide having a small amount of carbon dioxide adsorbed (desorbed) has a high oxygen absorption / desorption rate and an excellent oxygen supply capacity per unit time.
The method for quantifying the amount of carbon dioxide desorbed in the heated desorption method is not particularly limited, but is calculated from a comparison with the pulse area of the generated gas obtained when the temperature of calcium oxalate monohydrate is raised under the same conditions. It is preferable to do so. If the total amount of carbon dioxide desorbed from room temperature to 1000 ° C. in the temperature rise desorption method at a temperature rise rate of 40 ° C./min is 450 μmol / g or more, both the oxygen release rate and the oxygen adsorption rate will be slow. , 450 μmol / g, more preferably 300 μmol / g or less, still more preferably 150 μmol / g or less.

The following methods can be preferably used as a method for reducing the amount of carbon dioxide desorbed by increasing the temperature of the oxygen-excessive metal oxide itself. That is, the amount of carbon dioxide adsorbed on the oxygen-rich metal oxide is reduced by heat-treating at 400 ° C. or higher and lower than 950 ° C. under vacuuming or gas replacement so that the oxygen partial pressure is 10 kPa or less. Can be done. This is one of the methods for producing an oxygen-rich metal oxide having a large amount of carbon dioxide adsorbed as the oxygen-rich metal oxide of the present invention in the same manner as the regeneration treatment described later.
The treatment time depends on the treatment temperature, oxygen partial pressure, etc., but is usually preferably 1 to 5 hours in consideration of equipment load, productivity, and the like. Similarly, the degree of vacuum is preferably 10 kPa or less, more preferably 100 Pa or less, still more preferably 10 Pa or less. The lower limit of the degree of vacuum is not particularly limited as long as the degree of vacuum is such that the oxygen-excessive metal oxide is not reduced and decomposed, but is usually preferably 0.01 Pa or more. The gas used for the substitution is not particularly limited as long as the oxygen partial pressure is 10 kPa or less, but an inert gas such as _N2 gas or Ar gas is preferable. Similarly, the treatment temperature is preferably 400 ° C. or higher and lower than 950 ° C., more preferably 600 ° C. or higher and 850 ° C. or lower, and further preferably 650 ° C. or higher and 800 ° C. or lower. Treatment at a temperature equal to or higher than the above-mentioned lower limit is preferable because carbon dioxide is rapidly desorbed. On the other hand, when the value is not more than the upper limit, the growth of particles is promoted, the surface area is reduced, and the decrease in the adsorption rate is suppressed, which is preferable.

In the powder X-ray diffraction measurement, the oxygen-rich metal oxide of the present embodiment is indexed as having a hexagonal _LuBa (Zn, Al) _4O7 type structure for analysis of each peak. The radioactive source used in the powder X-ray diffraction measurement is not particularly limited, but the measurement can be performed with the generally used CuKα. Further, when the oxygen-rich metal oxide of the present invention contains a large amount of Mn, Fe, Co and the like, fluorescent X-rays may be generated and the background intensity may increase. In such a case, low-energy X-rays can be cut by using a monochromator or a detector having an energy filter function. Further, when the XRD measuring device is equipped with a fluorescent X-ray reduction mode, it is preferable to use it.
Further, it is preferable to use a semiconductor detector as the X-ray detector because of its high sensitivity. Further, using a semiconductor detector is preferable in terms of detection accuracy, because detection accuracy can be ensured even if a relatively simple Ni filter is used to cut CuKβ rays.
The oxygen-rich metal oxide of the present embodiment is a _LuBa (Zn, Al) _4O7 type characterized by a diffraction pattern having all of the following (a) to (d) in powder X-ray diffraction measurement. As an oxygen-excessive metal oxide having a crystal structure and having a total desorption amount of carbon dioxide from room temperature to 1000 ° C. in the temperature temperature desorption method at a temperature rise rate of 40 ° C./min, which is less than 450 μmol / g. Can also be defined.
(A) 110 peak (b) 103 peak (c) 112 peak (d) 201 peak At this time, Y, Ba and Co are at least 0.8 to 1.2: 0.8 to 1.2: It is preferably contained in a stoichiometric ratio of 3.2 to 4.8. The meaning of this ratio of Y, Ba and Co is that fluctuations due to defects or substitution with other elements can be tolerated within a range of about 20% from the stoichiometric composition.

The oxygen-rich metal oxide of the present embodiment has a diffraction peak similar to that of a conventionally known typical hexagonal _LuBa (Zn, Al) _4O7 type crystal structure in powder X-ray diffraction measurement. One feature is that the peak intensity of 103 in the hexagonal structure is smaller than the peak intensity of 110, and the half-value width of the peak of 103 is 0.3 ° or more. The half width of the peak of 103 is preferably 0.4 ° or more, more preferably 0.5 ° or more, and most preferably 0.7 ° or more.

Here, the half width of the peak of 103 means a value when CuKα is used as a radioactive source. Therefore, when a radiation source other than CuKα is used, the half width is a value read according to the wavelength of the radiation source used, that is, a value converted to CuKα. The measurement interval of 2θ in the powder X-ray diffraction measurement is not particularly limited, but is preferably 0.02 ° or less from the viewpoint of measurement accuracy. The same applies to other peaks (110, 112, 201, etc.).

The oxygen-rich oxide of the present embodiment does not have much difference in the peak intensity of 110 peaks, particularly the relative intensity of 110 peaks with respect to the peak of 112, which is the strongest line, with respect to the conventional oxygen-rich oxide. The half-value width does not change so much, but one feature is that the peak intensity of 103 changes very much. In the conventionally known oxygen-rich oxide, the peak intensity of 103 is usually 80% or more of the peak intensity of 112, which is the strongest line, whereas the peak of 110 is the peak intensity of 112. It was often about half. Further, the half width of the main peak on the low angle side such as 110, 103, 112 was 0.2 ° or less unless the crystallinity was poor. On the other hand, in the oxygen-rich oxide of the present embodiment, the half width of the 103 peak is widened to 0.3 ° or more. One of the features of this embodiment is that the change in the peak shape of 103 can be detected most clearly. Here, the peak intensity of 103 is preferably 80% or less, more preferably 70% or less, still more preferably 60% or less, and most preferably 50% or less of the peak intensity of 112.

Further, in a more preferable embodiment of the oxygen-rich oxide of the present embodiment, in addition to the above-mentioned feature of broadening the peak of 103, a feature that the change in the half-value width of 110 with respect to the conventional oxygen-rich oxide is small. Have. That is, in the oxygen-rich oxide of the present embodiment, the half-value width of the peak of 110 is smaller than the half-value width of the peak of 103, preferably 1/2 or less. The lower limit of the preferred half-value width ratio is not particularly limited, but in practice, it is generally 1/100 or more. In the oxygen-rich metal oxide of the present embodiment, the half-price width of the peak of a specific surface fluctuates particularly greatly because the oxygen-rich metal oxide of the present embodiment simply has poor crystallinity and crystallizers. It shows that the size of is not just small.
In terms of absolute value, the half width of the 110 peak is preferably less than 0.3 °, more preferably 0.25 ° or less. The lower limit of the half width of the 110 peak is not particularly limited. Similar to the conventional oxygen excess type oxide, 0.05 ° or more is preferable.

Further, focusing on a preferred embodiment of the present embodiment with another peak, the half width of the 201 peak of the oxygen-rich oxide of the present embodiment is preferably 0.25 ° or more, more preferably 0.3 ° or more. .. The 201 peak is also a peak with a relatively high peak intensity in the conventionally known oxygen-rich oxide, and generally has an intensity of about 90% of the 112 peak, which is the strongest line. In a preferred embodiment of the present embodiment, the peak intensity is reduced to 70% or less, and the peak height is reduced to the same level as the 110 peak.

In addition, the oxygen-rich oxide of the present embodiment also has peaks such as 213 and 205, but these peaks are the strengths of those conventionally known when viewed as the strength with respect to the 112 peak, which is the strongest line. The ratio was about 0.3, but the oxygen-rich oxide of the present embodiment preferably has these peaks of 0.2 or less, more preferably 0.15 or less.

As a specific measurement procedure in the analysis of the various peaks described above, the maximum value of each peak (diffraction line) is extracted, the background intensity is read, and the background intensity is subtracted from the maximum value of each peak (diffraction line). The value is taken as the peak intensity (diffraction line intensity) of each peak (diffraction line). This value is the peak intensity used herein. The ratio of each peak intensity can be obtained by taking this ratio. Here, the full width at half maximum (FWHM) is read as the full width at half maximum of the peak intensity after removing the background. In addition, each peak intensity obtained by obtaining the ratio of the peak intensity of 112 which is the strongest line and each peak intensity may be shown as the relative intensity with respect to 112 peak intensity (“Relative I”).

In the above powder X-ray diffraction measurement, having a diffraction peak similar to the crystal structure of hexagonal _LuBa (Zn, Al) _4O7 type means that all the clear peaks (a) to (d) below are defined. Means to have.
(A) 110 peak (b) 103 peak (c) 112 peak (d) 201 peak

In the oxygen-rich metal oxide of the present embodiment, the peak intensity of 201 in (d) is preferably smaller than the peak intensity of 112 in (c), and the peak intensity of 201 in (d) is the above (d). It is more preferably 80% or less, more preferably 70% or less, and particularly preferably 65% or less of the peak intensity of 112 in c).

On the other hand, the peak of the above (c) preferably has a sharp shape similar to that of the air-fired product. More specifically, the half width of the above (c) is preferably 0.05 ° or more and 0.3 ° or less, and more preferably 0.1 ° or more and 0.27 ° or less.

The oxygen-rich metal oxide of the present embodiment has an excellent oxygen adsorption / desorption ability, and when the temperature is moved up and down in the temperature range of 500 ° C. or lower, preferably 200 ° C. to 450 ° C., oxygen is released on the low temperature side. Adsorbs (absorbs) and desorbs (releases) oxygen on the high temperature side. That is, this utilizes the fact that the adsorption rate and the release rate are in equilibrium in the vicinity of 400 ° in the atmosphere, and when oxygen is absorbed and desorbed from the atmosphere, oxygen is typically taken out at a temperature of less than 350 ° C. It can be adsorbed and rapidly release oxygen in a high temperature region of about 350 to 400 ° C. Therefore, by repeating the temperature rise and fall, it is possible to create a gas having an oxygen concentration higher than that in the atmosphere, and conversely, it can be used to lower the oxygen concentration. That is, the oxygen-rich metal oxide of the present embodiment has advantageous properties as a practical material for oxygen storage or an oxygen selective membrane that requires repeated use cycles.

Further, the oxygen-rich metal oxide of the present embodiment preferably has an oxygen release rate of 0.5 wt% / min or more. In the present specification, the oxygen release rate is based on the weight at the time when the weight is allowed to stand in nitrogen at 350 ° C. and 1 atm so that the weight does not change, and then the weight is changed by standing in oxygen at 350 ° C. and 1 atm. After absorbing oxygen until it does not occur, when the atmospheric gas is switched to nitrogen at 350 ° C. and 1 atm, the weight decreases from 1.5 wt% heavier than the reference weight to 0.5 wt% heavier than the reference weight. It means the weight change (wt% / min) per unit time.

Further, the oxygen-rich metal oxide of the present embodiment preferably has an oxygen adsorption rate of 0.5 wt% / min or more. In the present specification, the oxygen adsorption rate is expressed by the weight change (wt% / min) per unit time when the cycle characteristics are evaluated in the examples described later, and the oxygen adsorption rate in the third cycle is expressed. Means speed.

The amount of oxygen adsorbed and desorbed can be controlled by temperature or partial pressure of oxygen. When it depends on the temperature, the pressure is not particularly limited, but it is usually carried out in the range of 0 to 100 atm. Typically, it may be carried out under atmospheric pressure, but it may also be carried out under pressurized conditions or under reduced pressure conditions depending on the conditions of use. Then, by using the oxygen-excessive metal oxide of the present embodiment, for example, an oxygen absorption / desorption device that adsorbs oxygen at a temperature lower than 350 ° C and releases oxygen in a high temperature range of about 350 to 400 ° C, or an oxygen absorption / desorption device at a temperature lower than 350 ° C. It is possible to realize an oxygen concentrator that concentrates oxygen by adsorbing oxygen and releasing oxygen in a high temperature region of about 350 to 400 ° C.
Next, a case of controlling by changing the oxygen partial pressure will be described. When the oxygen partial pressure is changed at 200 ° C. or higher and 400 ° C. or lower, oxygen is adsorbed (absorbed) on the side where the oxygen partial pressure is high, and oxygen is desorbed (released) on the side where the oxygen partial pressure is lower than that at the time of adsorption. The optimum oxygen partial pressure for desorption depends on the temperature of the oxygen-rich metal oxide during desorption. The lower the temperature at the time of absorption / desorption, the more likely it is that oxygen is absorbed at a lower oxygen partial pressure, and the higher the temperature, the more the amount of oxygen adsorbed tends to decrease even if the oxygen partial pressure is increased. Typically, adsorption may be performed under atmospheric pressure (oxygen partial pressure 20 kPa), but it may also be performed under pressurized conditions, and desorption may be performed under lower oxygen partial pressure than during adsorption, and decompression conditions. You can also do it below. In the oxygen-excessive metal oxide of the present embodiment, the higher the oxygen partial pressure, the more the amount of oxygen adsorbed tends to increase. Therefore, by repeating the increase and decrease of the oxygen partial pressure, the oxygen concentration is higher than that in the atmosphere. It can also be used to reduce oxygen concentration.
Further, both the temperature and the pressure may be changed and controlled.

The mode of use of the oxygen-rich metal oxide of the present embodiment is not particularly limited. For example, it can be used as a film dispersed in a matrix of powder, an agglomerate or porous body in which powder is aggregated, a composite material supported on the surface of a carrier, a resin, or the like. Further, the oxygen-rich metal oxide of the present embodiment can be used as a ceramic for storing oxygen or a ceramic for an oxygen selective film.

Further, by using the above-mentioned oxygen absorption / desorption principle of the oxygen-rich metal oxide of the present embodiment, an oxygen storage / separation / concentration device for storing, separating and / or concentrating oxygen; an oxidation reaction using the stored oxygen. Oxygen reactor that performs oxygen enrichment using stored oxygen; Oxygen concentrator that heats using the heat generated by oxygen storage, separation and / or concentration; Oxygen storage, separation and / Alternatively, a cooling device that cools using cold heat generated by concentration; a heat exchange device that exchanges heat using hot and / or cold heat generated by oxygen storage, separation, and / or concentration can be realized.

The high-concentration oxygen produced by using the oxygen-rich metal oxide of the present invention can be used in various industrial fields. Although not particularly limited, for example, when high-concentration oxygen is used, the fuel is burned in highly reactive high-concentration oxygen, the combustion temperature rises, and the efficiency of the boiler and the like can be improved. It can be reduced, and the exhaust gas amount is reduced accordingly, so the entire device can be made smaller and lighter, leading to efficiency improvement and cost reduction, and harmful nitrogen oxides can be reduced because the accompanying nitrogen gas content is suppressed. There are advantages of.

The specific use of the high-concentration oxygen produced by using the oxygen-rich metal oxide of the present invention is not particularly limited, but is not particularly limited, but is used for metal processing burners and various furnace blowing applications (steelmaking, non-ferrous metal melting, etc.). , Water treatment (oxygen aeration), hydrogen sulfide generation suppression, bio-related / culture / fermentation, glass processing burner, papermaking industry (drifting), oxidation reaction, ozone generator (water treatment, drifting, etc.) , Combustion device applications, internal combustion engine applications such as gasoline and diesel engines, fuel cell applications, oxygen generation applications in aircraft, transportation-related applications, air conditioner applications such as introducing oxygen-enriched air into the room, oxygen gas applications for health , Medical field use, live fish breeding use, food processing use, gas filling and packaging use, etc.

The method for producing an oxygen-rich metal oxide of the present embodiment has the above-mentioned stoichiometry, and the amount of carbon dioxide desorbed from room temperature to 1000 ° C. in the temperature rise desorption method at a temperature rise rate of 40 ° C./min. As long as an oxygen-excessive metal oxide having a total of less than 450 μmol / g can be obtained, it is not particularly limited. In particular, when the raw material contains carbonic acid, the amount of carbon dioxide adsorbed on the surface after firing tends to be large, so that the effect is great. From the viewpoint of obtaining the above-mentioned carbon dioxide desorption amount and / or powder X-ray diffraction pattern with good reproducibility, easily and at low cost, a production method using a low-temperature firing process is preferable. The details will be described below.

A preferred low-temperature firing process includes a method of firing the precursor of the above-mentioned oxygen-rich metal oxide in a low oxygen atmosphere having a lower oxygen content than in the atmosphere at a relatively lower temperature than before. Here, as the precursor, those containing at least the oxides of A, D, E and G, carbonates, acetates, citrates, nitrates and / or hydrates thereof can be used. At this time, it is preferable that the precursor contains oxides of A, D, E, G, acetate and the like in an effective molar ratio corresponding to the stoichiometry represented by the general formula (1). The effective molar ratio here means the molar ratio required to realize the stoichiometry represented by the general formula (1) after the firing treatment. (A) For example, when an oxygen-rich metal oxide of YBaCo ₄ O _{7 + δ} is obtained, the molar ratio of Y: Ba: Co to 1: 1: 4 is obtained by combining Y oxide, Ba carbonate, and Co oxide. (B) An aqueous solution prepared by mixing an acetate of Y, an acetate of Ba, and an acetate of Co so as to have a molar ratio of Y: Ba: Co of 1: 1: 4 is tentatively prepared. The calcined mixture, (c) further, the mixture obtained by tentatively calcining the aqueous solution obtained by salt-exchanged the aqueous solution with citric acid, and the like, (d) Y nitrate, Ba nitrate, and Co nitrate Y: Ba: Co is 1. A mixture obtained by tentatively firing an aqueous solution mixed so as to have a molar ratio of 1: 4 can be used as a precursor. As another method for producing the precursor, a precipitate such as ammonia, oxalic acid, or ammonium carbonate is added to a nitrate aqueous solution or the like containing each desired element to obtain a uniformly mixed precipitate, and the precipitate is obtained. A so-called co-precipitation material, which is recovered and dried, can also be preferably used.

The treatment temperature in the above-mentioned low-temperature firing process is not particularly limited as long as it is lower than the conventionally performed 1050 ° C. From the viewpoint of efficiently obtaining an oxygen-excessive metal oxide having excellent oxygen absorption / desorption performance and suppressed reduction of oxygen adsorption amount due to repeated use, the temperature is preferably 700 ° C. or higher and lower than 950 ° C., more preferably 720 ° C. As mentioned above, it is 930 ° C. or lower, more preferably 750 ° C. or higher and 850 ° C. or lower. Here, the firing temperature of less than 950 ° C. is a set temperature held at the time of firing, and is a set temperature of the firing furnace. Therefore, even if the temperature temporarily exceeds 950 ° C for a short time during temperature control during firing, the present invention is used as long as the temperature rises by, for example, about 50 K and the temperature is very short, unless it is extremely excessive. It shall be included in the intended "firing temperature of less than 950 ° C." The rate of temperature rise during firing may be appropriately set in consideration of the characteristics and productivity of the firing furnace to be used, and is not particularly limited. Generally, the standard is about 0.5 ° C./min to 10 ° C./min.
Further, the processing time is not particularly limited. Generally, about 5 to 24 hours is a guide. The time while holding at a constant processing temperature is defined as the processing time (calcination time) in the above-mentioned low-temperature firing process.

The above-mentioned low-temperature firing process is not particularly limited as long as the carbon dioxide concentration in the atmosphere gas in the furnace immediately before the start of temperature lowering is less than 0.01 vol% under a low oxygen atmosphere in which the oxygen content is lower than in the atmosphere. Here, a low oxygen atmosphere having an oxygen content lower than that in the atmosphere means that the oxygen content is 20% by volume or less, and an oxygen-free atmosphere containing substantially no oxygen (oxygen content is 0% by volume). ) Is a concept. From the viewpoint of efficiently obtaining an oxygen-excessive metal oxide having excellent oxygen absorption / desorption performance and suppressed reduction of oxygen adsorption amount due to repeated use, the oxygen content is preferably 5% by volume or less in the low-temperature firing process step. It is preferably 3% by volume or less, more preferably 1% by volume or less, and particularly preferably 20 ppm or less. Further, it is more preferable that the oxygen concentration is 5% by volume or less at the firing temperature, that is, at the time when the maximum temperature of the firing step is reached. The lower limit of the oxygen content is not particularly limited and may be 0% by volume or more. Specifically, it is preferable to carry out the operation in an inert gas atmosphere in which the oxygen content is within the above-mentioned preferable range. Examples of the inert gas include _N2 gas and Ar gas. Further, the processing pressure is not particularly limited. Generally, it may be performed under normal pressure, but it can also be performed under pressure or reduced pressure. In particular, from the viewpoint of preventing the inflow of oxygen from outside the furnace, firing under pressure is preferable.
Furthermore, if carbon dioxide is present in the atmosphere gas in the furnace during treatment at the firing temperature, it will be adsorbed on the oxygen-excessive metal oxide and the oxygen absorption / desorption ability will decrease. The carbon dioxide concentration is preferably less than 0.01 vol%, more preferably 0 vol%. When carbon dioxide is generated from the precursor, particularly when the raw material contains a carbonate, it is preferable to bake under reduced pressure from the viewpoint of preventing its adsorption.
Usually, carbon dioxide adsorbed on an oxygen-rich metal oxide includes carbon dioxide generated by inflow from outside the furnace or generated in the process of reacting a precursor to form an oxygen-rich metal oxide. In particular, it is difficult to adjust the concentration of carbon dioxide generated from the precursor, but if the concentration of carbon dioxide in the atmosphere gas in the furnace immediately before the start of temperature reduction can be kept low by the study of the present inventors, the present embodiment It was clarified that an oxygen-rich metal oxide can be obtained. Therefore, even if the carbon dioxide concentration increases during the temperature rise and / or the firing time of the low-temperature firing process, the carbon dioxide concentration in the atmosphere gas in the furnace immediately before the start of temperature reduction should be less than 0.01 vol%. The effect of the present invention can be obtained. In order to reduce the carbon dioxide concentration in the atmosphere gas in the furnace immediately before the start of temperature reduction to less than 0.01 vol%, specifically, the treatment time, the treatment temperature, the amount of the precursor, the flow rate of the atmosphere gas to be supplied, and the time of decompression The degree of vacuum and the like may be adjusted as appropriate to sufficiently exhaust the carbon dioxide generated just before the start of temperature reduction to the outside of the furnace.

After performing the above low-temperature firing process, the oxygen-rich metal oxide of the present embodiment can be obtained by cooling in the atmosphere or the like. The oxygen-rich metal oxide of the present embodiment preferably has a _LuBa (Zn, Al) _4O7 type crystal structure when oxygen is desorbed.

The chemical composition of the obtained oxygen-rich metal oxide can be determined according to a conventional method, for example, by an iodine titration method, an ICP emission spectrometry method, or the like. Specifically, the chemical composition of the oxygen-rich metal oxide (for example, _{YBaCo 4} O _{7 + δ )} represented by the general formula _{AjBkCmDnO7 +} δ can be obtained by the following procedure.
(1) Obtain the average valence of Co by the iodine titration method.
(2) The molar ratios of Y, Ba and Co are determined by ICP emission spectrometry.
(3) From the molar ratio, the values of j, k, m, and n in the above equation (1) are standardized so as to satisfy j + k + m + n = 6.
(4) From the average valence of Co and the values of j, k, m, and n normalized in (3), the number of oxygen atoms is obtained in consideration of the charge balance.
(5) The chemical composition is determined from the above calculation results.

The above-mentioned findings of the present invention can be applied even when the ability of the oxygen-rich metal oxide is reduced due to the usage environment. For example, when the oxygen-excessive metal oxide of the present invention is used for oxygen concentration by absorbing and desorbing oxygen by raising and lowering the temperature in the atmosphere, carbon dioxide in the atmosphere is adsorbed depending on the usage conditions, and oxygen It is conceivable that the ability to attach and detach the oxygen will decrease. At that time, by heating at an oxygen partial pressure of 10 kPa or less and at 400 ° C. or higher and lower than 950 ° C., the oxygen absorption / desorption ability of the oxygen-excessive metal oxide can be regenerated.
Such a regeneration process is performed, for example, when the amount of oxygen enriched per unit time of the oxygen concentrator becomes less than or equal to a predetermined amount, or when the number of times of enrichment reaches a certain number or more. It is preferable because the oxygen absorption / desorption ability can be returned to the original level. The preferable conditions at the time of this regeneration treatment are the same as the conditions described in the column of the manufacturing method.

That is, the amount of carbon dioxide adsorbed on the oxygen-rich metal oxide is reduced by performing heat treatment at 400 ° C. or higher and lower than 950 ° C. under vacuuming or gas replacement so that the oxygen partial pressure is 10 kPa or less. be able to. The treatment time depends on the treatment temperature, oxygen partial pressure, etc., but is usually preferably 1 to 5 hours in consideration of equipment load, productivity, and the like. Similarly, the degree of vacuum is preferably 10 kPa or less, more preferably 100 Pa or less, still more preferably 10 Pa or less. The lower limit of the degree of vacuum is not particularly limited as long as the degree of vacuum is such that the oxygen-excessive metal oxide is not reduced and decomposed, but is usually preferably 0.01 Pa or more. The gas used for the substitution is not particularly limited as long as the oxygen partial pressure is 10 kPa or less, but an inert gas such as _N2 gas or Ar gas is preferable. Similarly, the treatment temperature is preferably 400 ° C. or higher and lower than 950 ° C., more preferably 600 ° C. or higher and 850 ° C. or lower, and further preferably 650 ° C. or higher and 800 ° C. or lower. Treatment at a temperature equal to or higher than the above-mentioned lower limit is preferable because carbon dioxide is rapidly desorbed. On the other hand, when the value is not more than the upper limit, the growth of particles is promoted, the surface area is reduced, and the decrease in the adsorption rate is suppressed, which is preferable.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. The present invention can adopt various conditions as long as the gist of the present invention is not deviated and the object of the present invention is achieved.

(Comparative Example 1)
As a starting material, Y (CH ₃ COO) 3.4H ₂ O, Ba (CH ₃ COO) ₂ , Co (CH ₃ COO) _{2.4H 2} O, Y: Ba: Co = ₁ : 1: 4 mol Weighed to a ratio. Next, these were dissolved in pure water to prepare an aqueous acetate solution. The prepared aqueous solution was spray-dried to obtain a powder. The obtained powder was calcined in air at 600 ° C. for 7 hours to prepare a precursor. The obtained precursor was calcined at 800 ° C. for 12 hours in a nitrogen stream. The carbon dioxide concentration in the atmosphere gas in the furnace at the start of temperature lowering from 800 ° C. was 0.44 vol%. Then, it was pulverized and mixed in an agate mortar to obtain an oxygen-rich metal oxide (YBaCo ₄ O _{7 + δ} ) of Comparative Example 1.

(Example 1)
The oxygen-rich metal oxide (YBaCo ₄ O _{7 + δ} ) of Comparative Example 1 was vacuum-pulled (oxygen partial pressure 30 Pa or less) with a rotary pump and heat-treated at 700 ° C. for 2 hours to obtain the oxygen-rich metal oxide. Regeneration was carried out to obtain an oxygen-rich metal oxide (YBaCo ₄ O _{7 + δ} ) of Example 1.

(Example 2)
The oxygen-rich metal oxide (YBaCo ₄ O _{7 + δ} ) of Comparative Example 1 was vacuum-pulled (oxygen partial pressure 30 Pa or less) with a rotary pump and heat-treated at 750 ° C. for 4 hours to obtain the oxygen-rich metal oxide. Regeneration was carried out to obtain an oxygen-rich metal oxide (YBaCo ₄ O _{7 + δ} ) of Example 2.

(Example 3)
The precursor obtained in Comparative Example 1 was calcined in a nitrogen stream (oxygen partial pressure of 0.1 kPa or less) at 800 ° C. for 15 hours. The carbon dioxide concentration in the atmosphere gas in the furnace at the start of temperature lowering from 800 ° C. was 0 vol%. Then, it was pulverized and mixed in an agate mortar to obtain an oxygen-rich metal oxide (YBaCo ₄ O _{7 + δ} ) of Example 3.

<Powder X-ray diffraction measurement>
The powder X-ray diffraction measurement of the obtained oxygen-rich metal oxides of Comparative Example 1 and Examples 1, 2 and 3 was performed. FIG. 1 shows a powder X-ray diffraction pattern of each oxygen-rich metal oxide. In FIG. 1, in order from the top, Comparative Example 1 (at the time of production, the carbon dioxide concentration in the atmosphere gas in the furnace before the start of temperature lowering was 0.01 vol% or more), and Example 1 (heat treatment at 700 ° C. under vacuum after production). Yes), Example 2 (with heat treatment at 750 ° C under vacuum after preparation), Example 3 (at the time of preparation, the carbon dioxide concentration in the atmosphere gas in the furnace immediately before the start of temperature reduction is less than 0.01 vol%) powder X The linear diffraction patterns are shown respectively.
The measurement range was 2θ in the range of 10 ° to 65 °. However, since the main peak exists up to 60 °, the drawing shows up to 60 °. The measurement interval is 0.02 °, and the equipment and conditions used are as follows.
Equipment: X'Pert Pro MPD manufactured by PANalytical in the Netherlands
Acceleration voltage: 45kV
Current: 30mA

As shown in FIG. 1, in both Comparative Example 1 and Examples 1, 2 and 3, all the diffraction lines having high intensity are diffracted by the same unit cell as the hexagonal _LuBa (Zn, Al) _4O7 . I was able to index the line.

<CO ₂ gas concentration measurement>
At the time of firing the precursors of Comparative Examples 1 and 3, an intake pipe was inserted near the center of the furnace, and a sample was taken out from the start of temperature rise with a portable multi-gas measuring instrument (RX-515) manufactured by RIKEN KEIKI CO., LTD. Until then, the carbon dioxide concentration was measured at 5-minute intervals.

<Measurement of gas generated when the temperature rises 1>
The obtained oxygen-rich metal oxides of Comparative Example 1 and Example 1 were immediately set in a measuring device, and the gas species generated at the time of temperature rise from room temperature to 1000 ° C. and the amount thereof were measured. Table 1 shows the types of gas generated and their amounts. From Table 1, the amount of CO ₂ generated is 460 μmol / g in Comparative Example 1, whereas it is 94 μmol / g in Example 1. That is, in Example 1, it can be seen that the amount of CO ₂ generated is greatly reduced to about 1/5.
The measurement method and the equipment used are as follows. The sample was placed in a platinum boat, set in a quartz heating tube, and then heated to 1000 ° C. at 40 ° C./min under a He 80 cm flow. The outlet gas in the meantime was introduced into a mass spectrometer to measure the gas component. The quantification was calculated using the calibration curve of O ₂ in the air for O ₂ and the calibration curve of N ₂ in the air for H ₂ O and the relative sensitivity coefficient with N ₂ . CO and CO ₂ were calculated using the calibration curve of N ₂ assuming that the sensitivity is equivalent to that of N ₂ . Since two peaks were detected in O ₂ , the amount of gas generated in the low temperature region and the amount of gas generated in the high temperature region are shown in the table in this order.
Equipment: Cannon Anerva: AGS-7000

<Measurement of gas generated when the temperature rises 2>
The obtained oxygen-rich metal oxides of Comparative Examples 1 and Examples 1, 2 and 3 were immediately set in a measuring device, and the gas species generated at the time of temperature rise from room temperature to 1000 ° C. and the amount thereof were measured. Table 2 shows the types of gas generated and their amounts. From Table 2, the amount of CO ₂ generated is 543 μmol / g in Comparative Example 1, 69 μmol / g in Example 1, 10 μmol / g in Example 2, and 73 μmol / g in Example 3. .. That is, in Examples 1, 2 and 3, it can be seen that the amount of CO ₂ generated is greatly reduced to about 1/5 to 1/50.
The measurement method and the equipment used are as follows. The sample was placed in a platinum boat, set in a quartz heating tube, and then heated to 1000 ° C. at 40 ° C./min under a He 80 cm flow. The outlet gas in the meantime was introduced into a mass spectrometer to measure the gas component. O ₂ is quantified from the calibration curve of O ₂ in the air, and H ₂ O, CO, and CO ₂ are quantified by comparing with the peak area of the generated gas obtained when the temperature of calcium oxalate monohydrate is raised under the same conditions. did. Since two peaks were detected in O ₂ , the amount of gas generated in the low temperature region and the amount of gas generated in the high temperature region are shown in the table in this order.
Equipment: Cannon Anerva: AGS-7000

<Measurement of oxygen adsorption amount and oxygen release rate>
The obtained oxygen-excessive metal oxides of Comparative Example 1 and Examples 1, 2 and 3 were immediately set in a measuring device, and the amount of oxygen adsorbed and the oxygen release rate were measured. Here, the oxygen-rich metal oxides of Comparative Example 1 and Examples 1, 2 and 3 were held at 350 ° C. in a nitrogen stream, and the weight change when the gas atmosphere was switched to oxygen was measured. FIGS. 2, 3, 4, and 5 are graphs showing changes in thermogravimetric analysis of the oxygen-rich metal oxides of Comparative Example 1 and Examples 1, 2, and 3. As shown in FIGS. 2, 3, 4, and 5, in each of Comparative Example 1 and Examples 1, 2, and 3, a rapid increase in weight due to oxygen absorption was shown immediately after gas switching. At this time, the saturated weight at the time of oxygen adsorption was about 2 wt% without any significant difference between Comparative Example 1 and Examples 1, 2 and 3. Subsequently, when the gas was switched from oxygen to nitrogen, a rapid weight loss was observed with the release of oxygen. The oxygen release rate when the oxygen adsorption amount is changed from 1.5 wt% to 0.5 wt% is 0.25 wt% / min in Comparative Example 1, whereas it is 0.59 wt in Examples 1, 2 and 3, respectively. It can be seen that% / min, 0.60 wt% / min, and 0.87 wt% / min are improved from about 2.4 to 3.5 times.
From the above, the oxygen excess type metal oxides of Examples 1, 2 and 3 have an excellent oxygen absorption / release capacity of 0.5 wt% / min or more, and these oxygen release rates are high. It can be seen that the improvement is about 2 to 4 times that of Comparative Example 1.

<Evaluation of cycle characteristics>
Next, the cycle characteristics of the obtained oxygen-rich metal oxides of Comparative Example 1 and Examples 1, 2 and 3 were evaluated by TG thermogravimetric analysis. The results are shown in FIGS. 6, 7, 8 and 9. Here, in the air (oxygen concentration 21%), the temperature is kept at 470-480 ° C for 9 minutes to release oxygen, then the temperature is lowered from 470 ° C to 230 ° C in 7 minutes, and the temperature is raised from 230 ° C to 470 ° C in 5 minutes. The warming was repeated 3 times. The temperature and weight measurements were taken every second. The change in weight due to oxygen adsorption and desorption at that time was measured. In FIGS. 6, 7, 8 and 9, the temperature change is shown by a dotted line, and the weight change is shown by a solid line.

As shown in FIG. 6, the weight change of the oxygen-rich metal oxide of Comparative Example 1 was as small as about 1.0 wt%, but the decrease in the maximum oxygen adsorption amount with the increase in the number of cycles was not observed. It was also found that the responsiveness to the temperature swing during oxygen adsorption was poor and the oxygen adsorption rate was low. On the other hand, as shown in FIGS. 7, 8 and 9, the weight change of the oxygen-rich metal oxides of Examples 1, 2 and 3 is as large as about 2 wt%, and the maximum oxygen adsorption amount with the increase in the number of cycles is increased. No decline was observed. Furthermore, it was also found that the responsiveness (responsiveness) to the temperature swing at the time of oxygen adsorption was good and the oxygen adsorption rate was high. From the above, the oxygen-rich metal oxides of Examples 1, 2 and 3 not only have a large maximum oxygen adsorption amount and are practical, but also have a high oxygen adsorption rate and excellent durability for repeated use. Was confirmed.

Table 3 shows the temperature at which oxygen adsorption changes to release in Comparative Example 1 and Examples 1, 2 and 3 in the above cycle characteristic evaluation.

From this result, it can be seen that the oxygen-rich metal oxide of the present invention can release oxygen at a lower temperature, that is, from an earlier stage than the oxygen-rich metal oxide of the comparative example.

Table 4 shows the difference between the maximum amount of oxygen adsorbed in each cycle, the retention rate of the amount of adsorption at the third time, and the maximum amount of oxygen adsorbed at the first time and the third time.

From this result, it was found that the oxygen-rich metal oxide of the present invention is remarkably excellent because the adsorption amount is almost maintained in the initial state even when the adsorption and desorption in a short time are repeated three times. Comparing the absolute values of the maximum adsorption amount, when oxygen was absorbed and desorbed under the present test conditions, the oxygen-rich metal oxide of the present invention had an oxygen adsorption amount about twice that of Comparative Example 1. It can be seen that it has. This means that when the device is configured using the oxygen-rich metal oxide of the present invention, the size and weight can be reduced by about half, and the energy required for raising and lowering the temperature for oxygen absorption and desorption is required. Is halved, the temperature of the device can be easily controlled (the temperature can be easily made uniform), and the number of times of oxygen absorption and desorption per unit time can be increased, which is an extremely large effect.

<Evaluation of oxygen adsorption rate>
Further, from the results of the above cycle characteristics, it is clear from the figure that there is a large difference in the oxygen adsorption rate in each cycle between Comparative Example 1 and Examples 1, 2 and 3, but the difference is particularly remarkable. As the data, the oxygen adsorption rate when the oxygen adsorption amount is changed from 0.4 wt% to 0.9 wt% will be compared and explained.

The oxygen adsorption rates in the third cycle were 0.62 wt% / min, 0.66 wt% / min, and 0.99 wt% / min in Examples 1, 2 and 3, respectively, whereas in Comparative Example 1, they were 0. It was .14 wt% / min. From this, the oxygen-rich metal oxide of the present invention has an oxygen adsorption rate of 0.6 wt% / min or more when the oxygen adsorption amount is changed from 0.4 wt% to 0.9 wt% under the present test conditions. I understand. At the same time, the oxygen-rich metal oxide of the present invention exhibits an oxygen adsorption capacity of 1.5 wt% or more, more preferably 1.7 wt% or more even if oxygen is repeatedly absorbed and desorbed under the present test conditions. It can be seen that it is.

The oxygen-rich metal oxide of the present invention has excellent oxygen absorption / desorption ability, an extremely high oxygen absorption / desorption rate, and further high durability during repeated use, so that oxygen storage that requires repeated use cycles is required. It can be widely and effectively used as a practical material for oxygen concentration, oxygen separation, or oxygen selective membrane. In addition, since the oxygen absorption / desorption ability is enhanced as compared with the conventional case, it also contributes to miniaturization and energy saving in these applications. In addition, the retention rate of the amount of oxygen adsorbed is excellent, and the regeneration method of the present invention can easily regenerate the oxygen adsorption / desorption ability of the oxygen-excessive metal oxide, so that the oxygen-excessive metal oxide has a longer life. Is achieved, and economic efficiency is particularly enhanced. Further, since it is a material that operates in a relatively low temperature range, it is particularly useful as a practical material for cold regions such as a fuel cell and a three-way catalyst for an exhaust gas purification device of an automobile.

Claims (13)

The following general formula (1):
A _j D _k E _m G _n O _{7 + δ}・ ・ ・ (1)
(In the formula, A is one or more selected from the group consisting of trivalent rare earth elements and Ca.
D is one or more selected from alkaline earth metal elements, and is
E and G are each independently selected from one or more of the oxygen 4-coordinating elements, and at least one is a transition metal element.
j> 0 and k> 0, respectively, and m ≧ 0 and n ≧ 0, respectively, where j + k + m + n = 6 and 0 <δ ≦ 1.5. )
It has a stoichiometry represented by, and the total amount of carbon dioxide desorbed from room temperature to 1000 ° C. in the temperature desorption method at a heating rate of 40 ° C./min is less than 450 μmol / g. Type metal oxide. A in the general formula (1) includes Y.
The oxygen-rich metal oxide according to claim 1. D in the general formula (1) includes Ba.
The oxygen-rich metal oxide according to claim 1 or 2. E in the general formula (1) contains Co,
The oxygen-rich metal oxide according to any one of claims 1 to 3. In powder X-ray diffraction measurement, it has a _LuBa (Zn, Al) _4O7 type crystal structure characterized by a diffraction pattern having all of the following (a) to (d).
(A) 110 peaks (b) 103 peaks (c) 112 peaks (d) 201 peaks Desorption amount of carbon dioxide from room temperature to 1000 ° C. in the temperature rise desorption method at a heating rate of 40 ° C./min. Is less than 450 μmol / g,
Oxygen-rich metal oxide. The precursor of the excess oxygen type metal oxide is heat-treated at an oxygen partial pressure of 10 kPa or less, at 700 ° C. or higher and lower than 950 ° C., and at a carbon dioxide concentration of less than 0.01 vol% in the atmosphere gas in the furnace immediately before the start of temperature reduction. can get,
The oxygen-rich metal oxide according to any one of claims 1 to 5. The oxygen absorption / desorption device using the oxygen-excessive metal oxide according to any one of claims 1 to 6. The oxygen absorption / desorption device according to claim 7, wherein oxygen is adsorbed on the oxygen-excessive metal oxide at a temperature lower than 350 ° C., and oxygen is released from the oxygen-excessive metal oxide at 350 ° C. or higher. A claim that oxygen is adsorbed on the oxygen-rich metal oxide in the presence of oxygen at 200 ° C. or higher and 400 ° C. or lower, and oxygen is released from the oxygen-rich metal oxide under a pressure at which the oxygen partial pressure is lower than that at the time of oxygen adsorption. Item 7. The oxygen suction / desorption device according to Item 7. Using the oxygen-rich metal oxide according to any one of claims 1 to 6,
An oxygen concentrator that concentrates oxygen by adsorbing oxygen to the oxygen-rich metal oxide at a temperature lower than 350 ° C. and releasing oxygen from the oxygen-rich metal oxide at 350 ° C. or higher. Using the oxygen-rich metal oxide according to any one of claims 1 to 6,
At 200 ° C. or higher and 400 ° C. or lower, oxygen is adsorbed on the oxygen-rich metal oxide in the presence of oxygen, and oxygen is released from the oxygen-rich metal oxide under a pressure at which the oxygen partial pressure is lower than that at the time of oxygen adsorption. An oxygen concentrator that concentrates oxygen by means of. The following general formula (1):
A _j D _k E _m G _n O _{7 + δ}・ ・ ・ (1)
(During the ceremony,
A is one or more selected from the group consisting of trivalent rare earth elements and Ca.
D is one or more selected from alkaline earth metal elements, and is
E and G are each independently selected from one or more of the oxygen 4-coordinating elements, and at least one is a transition metal element.
j> 0 and k> 0, respectively, and m ≧ 0 and n ≧ 0, respectively, where j + k + m + n = 6 and 0 <δ ≦ 1.5. )
The precursor of the oxygen-excessive metal oxide having stoichiometry represented by is oxygen partial pressure of 10 kPa or less, 700 ° C. or higher, less than 950 ° C., and the carbon dioxide concentration in the atmosphere gas in the furnace immediately before the start of temperature lowering is 0. A method for producing an oxygen-rich metal oxide, which comprises heat-treating at less than 01 vol%. The following general formula (1):
A _j D _k E _m G _n O _{7 + δ}・ ・ ・ (1)
(During the ceremony,
A is one or more selected from the group consisting of trivalent rare earth elements and Ca.
D is one or more selected from alkaline earth metal elements, and is
E and G are each independently selected from one or more of the oxygen 4-coordinating elements, and at least one is a transition metal element.
j> 0 and k> 0, respectively, and m ≧ 0 and n ≧ 0, respectively, where j + k + m + n = 6 and 0 <δ ≦ 1.5. )
The oxygen-excessive metal oxide having the stoichiometry represented by the above is heated at an oxygen partial pressure of 10 kPa or less, 400 ° C. or higher, and lower than 950 ° C.
A method for regenerating an oxygen-rich metal oxide.

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