JP2016193815A - Oxygen excess type metal oxide and production method therefor, and oxygen concentration apparatus and oxygen adsorption and desorption apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide novel oxygen excess type metal oxide excellent in oxygen adsorption and desorption speed and having suppressed reduction of oxygen adsorbed amount caused by repeated use, a production method therefor or the like.SOLUTION: There is provided oxygen excess type metal oxide which is represented by a formula (1) and in which peak strength of 103 of a hexagonal structure is smaller than peak strength of 110 and half value width of peak of 103 (FWHM) is 0.3° or more when measured by an X-ray powder diffraction method. ADEGO(1), where A is a trivalent rare earth element or Ca, D is one or more kind selected from alkali earth metal elements, E and G are each independently one or more kind selected from oxygen tetracoordination element and at least one kind is a transition metal element, j>0, k>0, each independently m≥0, n≥0, j+k+m+n=6 and 0<δ≤1.5.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an oxygen-excess metal oxide, a method for producing the same, an oxygen concentrator, and an oxygen adsorption / desorption device.

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

As such a metal oxide, the present inventors have newly developed and already reported an oxygen-excess type metal oxide having oxygen nonstoichiometry (nonstoichiometric amount: δ). That is, the oxygen-excess metal oxide represented by the general formula of such _{YBaCo 4 O 7 + δ A j} B k C m D n O 7 + δ is, the low temperature region below 500 ℃, a large amount of oxygen, especially 200 to 400 ° C. It has been found that it has a remarkable thermogravimetric change property of absorbing oxygen rapidly and releasing oxygen when the temperature rises, and reports that it has performance suitable as a ceramic for high performance oxygen storage or oxygen selective membranes (See Patent Document 1). Further, it has been reported that this oxygen-excess metal oxide causes a phase change at the time of oxygen adsorption / desorption (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 sought to further improve the oxygen adsorption / desorption ability of the oxygen-excess metal oxide. In addition, there is room for improvement in the oxygen adsorption / desorption rate in the oxygen adsorption / desorption capacity, and when oxygen adsorption / desorption is repeated in a short time when the adsorption amount does not reach saturation, the oxygen adsorption amount is reduced within the repetition cycle. We found that there are challenges to reduce.

  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-excess metal oxide and a method for producing the same, which have an excellent oxygen adsorption / desorption rate and suppress a reduction in the amount of oxygen adsorbed by repeated use. Another object of the present invention is to provide a novel oxygen concentrating device, oxygen adsorbing / desorbing device and the like using the oxygen-excess metal oxide.

The present inventors diligently studied to solve the above problems. Tolerance Consequently, while having the same stoichiometry as the conventional oxygen-excess type metal oxide represented by the general formula _{A j B k C m D n} O 7 + δ described above, the oxygen desorption than conventional The present inventors have succeeded in synthesizing an oxygen-excess type metal oxide having a crystal structure excellent in (Tolerance), and found that the above problem can be solved by using this oxygen-excess type metal oxide, and have reached the present invention.

That is, the present invention provides specific embodiments shown in the following (1) to (21).
(1) The following general formula (1):
A _j D _k E _m G _n O _{7 + δ} (1)
(Where
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,
E and G are each independently one or more selected from oxygen tetracoordinate elements, and at least one is a transition metal element,
j> 0, k> 0, and independently m ≧ 0 and n ≧ 0, provided that j + k + m + n = 6 and 0 <δ ≦ 1.5. )
In the powder X-ray diffraction measurement, the peak intensity of 103 of the hexagonal crystal structure is smaller than the peak intensity of 110, and the half width (FWHM) of the peak of 103 is 0.3. ° or more,
Oxygen-rich metal oxide.

(2) Standing in nitrogen at 350 ° C. and 1 atm. The weight when no change in weight occurred was taken as the reference weight, then standing in oxygen at 350 ° C. and 1 atm to absorb oxygen until no change in weight occurred. Thereafter, when the atmospheric gas is switched to nitrogen at 350 ° C. and 1 atm, the oxygen release rate until the oxygen gas decreases from 1.5 wt% heavier than the reference weight to 0.5 wt% heavier than the reference weight is 0.5 wt%. The oxygen-excess metal oxide according to (1) above, which is at least / min.
(3) The oxygen-excess metal oxide according to the above (1) or (2), wherein A in the general formula (1) contains Y.
(4) The oxygen-excess type metal oxide according to any one of (1) to (3), wherein D in the general formula (1) contains Ba.
(5) The oxygen-excess metal oxide according to any one of (1) to (4), wherein E in the general formula (1) contains Co.

(6) In the powder X-ray diffraction measurement, it has a LuBa (Zn, Al) ₄ O ₇ type crystal structure characterized by a diffraction pattern having all of the following (a) to (d):
(A) 110 peak (b) 103 peak (c) 112 peak (d) 201 peak (b) The peak intensity is smaller than the peak intensity of (a), and the half width of (a) is It is 1/2 or less of the half value width of (b), and the half value width of (b) is 0.3 ° or more.
The oxygen-excess type metal oxide according to any one of (1) to (5) above.

(7) An oxygen adsorption / desorption device using the oxygen-excess metal oxide according to any one of (1) to (6) above.
(8) The oxygen adsorption / desorption device according to (7), wherein oxygen is adsorbed to the oxygen-excess metal oxide at less than 350 ° C., and oxygen is released from the oxygen-excess metal oxide at 350 ° C. or more.
(9) At 200 ° C. or more and 400 ° C. or less, oxygen is adsorbed to the oxygen-excess type metal oxide in the presence of oxygen, and oxygen is absorbed from the oxygen-excess type metal oxide at a pressure lower than the oxygen adsorption. Release
The oxygen adsorption / desorption device according to (7) above.
(10) Using the oxygen-excess type metal oxide according to any one of (1) to (6) above, oxygen is adsorbed to the oxygen-excess type metal oxide at less than 350 ° C., and at 350 ° C. or more An oxygen concentrator that concentrates oxygen by releasing oxygen from an oxygen-excess metal oxide.
(11) Using the oxygen-excess metal oxide according to any one of (1) to (6) above, oxygen is added to the oxygen-excess metal oxide in the presence of oxygen at 200 ° C. or more and 400 ° C. or less. An oxygen concentrator for concentrating oxygen by adsorbing and releasing oxygen from the oxygen-excess metal oxide under a pressure lower than that during oxygen adsorption.

(12) Oxygen storage / separation / concentration comprising the oxygen-excess metal oxide according to any one of (1) to (6) above, wherein oxygen is stored, separated and / or concentrated. apparatus.
(13) An oxidation reaction apparatus comprising the oxygen-excess metal oxide according to any one of (1) to (6) above, and performing an oxidation reaction using stored oxygen.
(14) The oxygen-rich metal oxide according to any one of (1) to (6) above, which is heated using heat generated by storage, separation and / or concentration of oxygen. And a heating device.
(15) The apparatus includes the oxygen-excess metal oxide according to any one of (1) to (6) above, and cooling is performed using cold heat generated by oxygen storage, separation, and / or concentration. And a cooling device.
(16) The oxygen-excess type metal oxide according to any one of (1) to (6) above, and heat exchange using hot and / or cold generated by oxygen storage, separation and / or concentration A heat exchange device characterized in that

(17) The oxygen-excess metal oxide precursor is calcined at 700 ° C. or higher and lower than 950 ° C. in a low oxygen atmosphere having an oxygen content lower than that in the atmosphere.
The following general formula (1):
A _j D _k E _m G _n O _{7 + δ} (1)
(Where
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,
E and G are each independently one or more selected from oxygen tetracoordinate elements, and at least one is a transition metal element,
j> 0, k> 0, and independently m ≧ 0 and n ≧ 0, provided that j + k + m + n = 6 and 0 <δ ≦ 1.5. )
The manufacturing method of the oxygen excess type metal oxide which has at least stoichiometry represented by these.

(18) The oxygen-excess type metal oxide having at least stoichiometry represented by the general formula (1) has a peak intensity of 103 having a hexagonal structure smaller than a peak intensity of 110 in powder X-ray diffraction measurement, And the manufacturing method of the oxygen excess type metal oxide as described in said (17) whose half width of the peak of 103 is 0.3 degree or more.
(19) The oxygen-excess metal oxide having at least stoichiometry represented by the general formula (1) is characterized by a diffraction pattern having all of the following (a) to (d) in powder X-ray diffraction measurement. Having a LuBa (Zn, Al) ₄ O ₇ type crystal structure attached;
(A) 110 peak (b) 103 peak (c) 112 peak (d) 201 peak (b) The peak intensity is smaller than the peak intensity of (a), and the half width of (a) is It is 1/2 or less of the half value width of (b), and the half value width of (b) is 0.3 ° or more.
The method for producing an oxygen-excess metal oxide according to the above (17) or (18).

(20) The method for producing an oxygen-excess metal oxide according to any one of (17) to (19), wherein the firing is performed in an atmosphere having an oxygen content of 5% by volume or less.
(21) In an effective molar ratio corresponding to stoichiometry represented by the general formula (1), the oxides, carbonates, acetates, citrates, nitrates, and / or the A, D, E and G The method for producing an oxygen-excess metal oxide according to any one of the above (17) to (20), which is prepared from a precursor containing at least these hydrates.

Moreover, this invention can be defined also as an aspect shown to the following (22)-(24).
(22) containing Y, Ba and Co in a stoichiometric ratio of at least 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) ₄ O ₇ type crystal structure characterized by a diffraction pattern having all of the following (a) to (d):
(A) 110 peak (b) 103 peak (c) 112 peak (d) 201 peak (b) The peak intensity is smaller than the peak intensity of (a), and the half width of (a) is It is 1/2 or less of the half value width of (b), and the half value width of (b) is 0.3 ° or more.
Oxygen-rich metal oxide.

(23) Standing in nitrogen at 350 ° C. and 1 atm. The weight when no change in weight was taken as the reference weight, and then standing in oxygen at 350 ° C. and 1 atm to absorb oxygen until no change in weight occurred. Thereafter, when the atmospheric gas is switched to nitrogen at 350 ° C. and 1 atm, the oxygen release rate until the oxygen gas decreases from 1.5 wt% heavier than the reference weight to 0.5 wt% heavier than the reference weight is 0.5 wt%. The oxygen-excess metal oxide according to (22), which is at least / min.
(24) The following general formula (1):
A _j D _k E _m G _n O _{7 + δ} (1)
(Where
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,
E and G are each independently one or more selected from oxygen tetracoordinate elements, and at least one is a transition metal element,
j> 0, k> 0, and independently m ≧ 0 and n ≧ 0, provided that j + k + m + n = 6 and 0 <δ ≦ 1.5. )
The oxygen-excess metal oxide according to (22) or (23), which has at least stoichiometry represented by:

  When the temperature or oxygen partial pressure is moved up and down in the temperature range of 500 ° C. or lower, the oxygen-excess metal oxide of each of the above aspects of the present invention exhibits an abnormal thermogravimetric change in the low temperature region. According to the knowledge of the present inventors, it has been clarified that the abnormal thermogravimetric change is caused by the change in the oxygen non-stoichiometry (unstoichiometric amount: δ) described above. That is, the oxygen-excess metal oxide of each of the above aspects of the present invention typically adsorbs a large amount of oxygen rapidly at less than 350 ° C., and rapidly absorbs a large amount of oxygen in a high temperature region of about 350 to 400 ° C. Release. Further, a large amount of oxygen is adsorbed in the presence of oxygen at 200 ° C. or more and 400 ° C. or less, and a large amount of oxygen is rapidly released under a pressure lower than the oxygen adsorption.

  Moreover, surprisingly, the oxygen-excess metal oxide of each of the above aspects of the present invention has a very high oxygen adsorption / desorption rate as compared with the conventional oxygen-excess metal oxide, Furthermore, it has been found that even when the oxygen adsorption / desorption is repeated, the oxygen adsorption amount in the repeated cycle is suppressed from being lowered.

That is, the oxygen-excess metal oxide of each aspect of the present invention is the same as the oxygen-excess metal oxide represented by the general formula A _j B _k C _m D _n O _{7 + δ} that has been conventionally known. In addition to having at least stoichiometry represented by the formula (1), among the characteristic peaks of the hexagonal LuBa (Zn, Al) ₄ O ₇ type crystal structure, the peak intensity of 103 of the hexagonal crystal structure One characteristic is that is smaller than the peak intensity of 110 and the half width (FWHM) of the peak of 103 is 0.3 ° or more. In the present specification, the peak intensity means the maximum value of the diffraction line. Further, the half width of the peak FWHM (F ull W idth at H alf M aximum), i.e. means full width at half maximum.
The typical hexagonal LuBa (Zn, Al) ₄ O ₇ type crystal structure known so far has a sharp peak 103 and a narrow half-value width. At first glance, a diffraction pattern having a broad peak with a low peak height can be evaluated as having many defects in the crystal and insufficient growth of the primary particles of the crystal. However, when the adsorption / desorption performance of these oxygens was measured, those having a diffraction pattern having a broad peak with a low peak height were inferior in oxygen maximum adsorption capacity compared to conventional ones, but oxygen The adsorption / desorption speed is fast, and repeated repeated adsorption / desorption in a short time does not reduce the maximum oxygen adsorption capacity within the unit time. From the knowledge of the present inventors, it was found that the XRD peak obtained by baking at a high temperature in oxygen known to be suitable for oxygen desorption rather than having a sharp crystal structure. It was done.
The reason for this is not clear, but in the oxygen-excess type metal oxide of each of the above aspects of the present invention, the regularity of the crystal is moderately relaxed, and the diffusion for the oxide ion to move at high speed in the crystal It is presumed that the oxygen adsorption / desorption rate is very high as a result of sufficiently securing the path and increasing the degree of freedom of oxygen adsorption / desorption. Further, in the oxygen-excess type metal oxide of each of the above aspects of the present invention, a phase change occurs during oxygen desorption as described in the aforementioned non-patent document. It has been confirmed that even when oxygen is desorbed after the phase change, the crystal structure before the phase change is maintained without returning to another well-known crystal structure. From these facts, the structure in which a specific peak of XRD becomes broad is a new structure that is different from the structure known heretofore, and has not developed a sufficient crystal structure. Is not just bad. And it is guessed that maintenance of this crystal structure leads to suppression of the fall of the oxygen adsorption amount in the repetition cycle at the time of repeating oxygen adsorption-desorption. However, the action is not limited to these.

  On the other hand, the method for producing an oxygen-excess type metal oxide of each aspect of the present invention is a production method capable of effectively obtaining the oxygen-excess type metal oxide of each aspect of the present invention described above, wherein the oxygen content is A process of baking at 700 ° C. or higher and lower than 950 ° C. in a low oxygen atmosphere lower than the atmosphere is provided. Conventionally, high temperature treatment at about 1100 ° C. has been performed in the atmosphere from the viewpoint of reducing crystal defects and the like. On the other hand, the production method of the present invention performs the firing under the condition where the oxygen partial pressure is lower and the processing temperature is lower than in the conventional method, so that the oxygen-excess type metal oxide having the above-described characteristics different from the conventional one is obtained. Can be obtained with good reproducibility.

  According to the present invention, a novel oxygen-excess metal oxide having improved oxygen adsorption / desorption performance can be provided. More specifically, not only is the oxygen adsorption / desorption amount excellent, but also the oxygen adsorption / desorption rate is high, and moreover, it is possible to provide an oxygen-excess type metal oxide in which performance deterioration during repeated use is suppressed. A practical ceramic material for oxygen storage or oxygen selection is realized. Moreover, according to this invention, the practical manufacturing method which can obtain this novel oxygen excess type metal oxide simply with sufficient reproducibility can be provided. By using the oxygen-excess metal oxide of the present invention, an oxygen concentrator, an oxygen adsorption / desorption device, and the like excellent in practical performance can be provided.

It is a figure which shows the result of the powder X-ray-diffraction measurement of Examples 1-3 and the oxygen excess type metal oxide of the comparative example 1. It is a figure which shows the oxygen adsorption | suction and oxygen desorption behavior of the oxygen excess type metal oxide of the comparative example 1. It is a figure which shows the oxygen adsorption | suction and oxygen desorption behavior of the oxygen excess type metal oxide of Example 1. It is a figure which shows the oxygen adsorption | suction and oxygen desorption behavior of the oxygen excess type metal oxide of Example 2. It is a figure which shows the oxygen adsorption | suction and oxygen desorption behavior of the oxygen excess type metal oxide of Example 3. It is a figure which shows the oxygen adsorption amount and oxygen adsorption-desorption rate of the oxygen excess type metal oxide of the comparative example 1. It is a figure which shows the oxygen adsorption amount and oxygen adsorption / desorption rate of the oxygen excess type metal oxide of Example 1. It is a figure which shows the oxygen adsorption amount and oxygen adsorption-desorption rate of the oxygen excess type metal oxide of Example 2. It is a figure which shows the oxygen adsorption amount and oxygen adsorption-desorption rate of the oxygen excess type metal oxide of Example 3. It is a figure which shows the change of the X-ray-diffraction pattern by oxygen adsorption / desorption of the oxygen excess type metal oxide of Example 2. FIG. 4 is a diagram showing the cycle characteristics of oxygen adsorption / desorption of the oxygen-excess metal oxide of Comparative Example 1. It is a figure which shows the cycling characteristics of the oxygen adsorption / desorption of the oxygen excess type metal oxide of Example 1. It is a figure which shows the cycling characteristics of the oxygen adsorption / desorption of the oxygen excess type metal oxide of Example 2. It is a figure which shows the cycling characteristics of the oxygen adsorption / desorption of the oxygen excess type metal oxide of Example 3.

  Hereinafter, embodiments of the present invention will be described in detail. However, the following embodiments are examples for explaining the present invention, and the present invention is not limited thereto, and does not depart from the gist thereof. Any change can be made within the range.

The oxygen-excess type metal oxide of this embodiment has at least stoichiometry represented by the following general formula (1). In the powder X-ray diffraction measurement, the peak intensity of 103 having a hexagonal structure is 110. The peak half-width (FWHM) of the peak of 103 is 0.3 ° or more.
A _j D _k E _m G _n O _{7 + δ} (1)
(Where
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,
E and G are each independently one or more selected from oxygen tetracoordinate elements, and at least one is a transition metal element,
j> 0, k> 0, and independently m ≧ 0 and n ≧ 0, provided that j + k + m + n = 6 and 0 <δ ≦ 1.5. )

  In this specification, “having at least stoichiometry” represented by the above general formula (1) means that each of the elements A, D, and E stoichiometrically represented in the above general formula (1). , G and O at a ratio shown in the above general formula (1), and further containing elements other than A, D, E, G and O (hereinafter also simply referred to as “other elements”). Means good. That is, the oxygen-excess metal oxide of the present embodiment may contain other elements as unavoidable impurities or as optional blending components in addition to the elements shown in the general formula (1).

  In the 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 of 57 to 71. Among these, Y is preferable. Further, since a plurality of elements can be dissolved in the site occupied by A (A site), it is preferable that A is two kinds of Y and Ca, and further, A is composed of three or more kinds of elements. It may be. Here, A preferably contains 50 mol% or more of Y, more preferably 80 mol% or more, and still more preferably 90 mol% or more. In addition, although the upper limit of the content rate of Y is not specifically limited, A contains Y 100 mol% or less, More preferably, it is 99.9 mol% or less, More preferably, it is 99.5 mol% or less.

  In the general formula (1), D is one or more selected from alkaline earth metal elements. Examples of alkaline earth metal elements include Sr and Ba. In addition, in this specification, Ca shall correspond to A in the said General formula (1), and shall not correspond to D. Here, D preferably contains Ba or Sr. Further, since a plurality of elements can be dissolved in the site occupied by D (D site), it is preferable that D is two kinds of Ba and Sr, and further, D is composed of three or more kinds of elements. May be. Here, D preferably contains 50 mol% or more of Ba, more preferably 80 mol% or more, and still more preferably 90 mol% or more. In addition, although the upper limit of the content rate of Ba is not specifically limited, It is preferable that D contains 100 mol% or less of Ba, More preferably, it is 99.9 mol% or less, More preferably, it is 99.5 mol% or less.

  E and G are each independently one or more elements selected from oxygen tetracoordinate elements, that is, oxygen tetracoordinate elements. In this specification, the oxygen tetracoordinate 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 tetracoordinate 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 sum of E and G, it is preferable to contain 50 mol% or more of Co, more preferably 75 mol% or more, and still more preferably 87.5 mol% or more. The upper limit of the content ratio of Co is not particularly limited, but it is preferable to include 100 mol% or less, more preferably 99.9 mol% or less, and 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 normalized with these totals set to 6. That is, when j + k + m + n = 6, j> 0, k> 0, m ≧ 0, and n ≧ 0, respectively. 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. 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 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-excess 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. Further, compounds described in Table 2 and Table 3 on 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 include _{0 + δ} , ErBaCo ₄ O _{7.0 + δ} , HoBaCo ₄ O _{7.0 + δ} , DyBaCo ₄ O _{7.0 + δ,} and compounds exemplified above, in which Ba is replaced with Sr. Specific combinations of elements include YBaCo ₃ ZnO _{7.0 + δ} , YBaCo ₂ Zn ₂ O _{7.0 + δ} , YBaCoZn ₃ O _{7.0 + δ} , YBaCo ₃ FeO _{7.0 + δ} , YBaZn ₃ FeO _{7.0 + δ, and the} like. . Furthermore, in these compounds, those in which 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 3 ZnO 7.0 + δ, and, CaBaCo ₂ Zn ₂ And O _{7.0 + δ} . Furthermore, in these compounds, Ba may be substituted with Sr.

  In this embodiment, the stoichiometry of the oxygen-excess metal oxide can be measured by, for example, an inductively coupled plasma (ICP) emission analysis method or an oxidation-reduction titration method such as an iodometric titration method. Note that oxygen is somewhat desorbed depending on the production conditions, the standing time in the atmosphere, and the temperature thereof, and it goes without saying that measurement is preferably performed after annealing in an inert gas.

The oxygen-rich metal oxide of this embodiment has a diffraction peak similar to a typical hexagonal LuBa (Zn, Al) ₄ O ₇ type crystal structure conventionally known in powder X-ray diffraction measurement. One feature is that the peak intensity of the hexagonal structure 103 is smaller than the peak intensity of 110, and the half width of the peak of 103 is 0.3 ° or more. The half width of the peak at 103 is preferably 0.4 ° or more, more preferably 0.5 ° or more, and most preferably 0.7 ° or more.

Here, in the powder X-ray diffraction measurement, the analysis of each peak is performed by indexing the hexagonal LuBa (Zn, Al) ₄ O ₇ type structure. In addition, although the radiation source used in powder X-ray diffraction measurement is not specifically limited, it can measure with CuK (alpha) generally used. Here, the half width of the peak at 103 means a value when CuKα is used as the radiation source. Therefore, when a radiation source other than CuKα is used, the full width at half maximum is a value read according to the wavelength of the used radiation source, that is, a value converted to CuKα. In addition, 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 the other peaks (110, 112, 201, etc.).
When the oxygen-excess metal oxide of this embodiment contains a large amount of Mn, Fe, Co, etc., fluorescent X-rays may be generated and the background intensity may be increased. In such a case, low energy X-rays can be cut by using a monochromator or using a detector having an energy filter function. Moreover, when the XRD measurement apparatus is equipped with the 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 from the viewpoint of high sensitivity. The use of a semiconductor detector is preferable in terms of detection accuracy because detection accuracy can be ensured even when a relatively simple Ni filter is used for cutting the CuKβ line.

  In the oxygen-excess type oxide of this embodiment, the peak intensity of the 110 peak, particularly the relative intensity of the 110 peak with respect to the 112 peak which is the strongest line, is not much different from the conventional oxygen-excess type oxide. Although the half width does not change so much, there is one feature in that the peak intensity of 103 has changed very greatly. In a conventionally known oxygen-excess type 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 has a peak intensity of 112. Often it was about half. Further, the half-value widths of main peaks on the low angle side such as 110, 103, and 112 were 0.2 ° or less unless the crystallinity was poor. On the other hand, in the oxygen-excess type oxide of the present embodiment, the half width of the 103 peak spreads to 0.3 ° or more. It is one of the features of this embodiment 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 of the peak intensity of 112, more preferably 70% or less, still more preferably 60% or less, and most preferably 50% or less.

In addition, in a more preferable aspect of the oxygen-excess type oxide of the present embodiment, in addition to the above-described feature of broadening the peak of 103, the feature that the change in the half width of 110 with respect to the conventional oxygen-excess type oxide is small Have. That is, in the oxygen-excess type oxide of the present embodiment, the half width of the 110 peak is smaller than the half width of the 103 peak, and preferably ½ or less. The lower limit of the preferred half width ratio is not particularly limited, but is practically 1/100 or more. In the oxygen-excess type metal oxide of the present embodiment, the half-value width of the peak of a specific plane varies particularly greatly. This indicates that the oxygen-excess type metal oxide of the present embodiment simply has poor crystallinity and a crystallite. Indicates that the size is not just small.
In terms of absolute value, the full width at half maximum of the 110 peak is preferably less than 0.3 °, more preferably 0.25 ° or less. In addition, the lower limit of the half width of the 110 peak is not particularly limited. Like the conventional oxygen-excess type oxide, 0.05 ° or more is preferable.

  Further, when attention is paid to another preferable peak of the present embodiment, the half width of the 201 peak of the oxygen-excess type oxide of the present embodiment is preferably 0.25 ° or more, more preferably 0.3 ° or more. . The 201 peak is also a peak having a relatively high peak intensity in a conventionally known oxygen-excess type oxide, and generally has an intensity of about 90% of the 112 peak which is the strongest line. In a preferred aspect of this embodiment, the peak intensity is reduced to 70% or less, and is reduced to a peak height similar to the 110 peak.

  In addition, in the oxygen-excess type oxide of the present embodiment, other peaks such as 213 and 205 also appear, but these peaks are intensities in the conventionally known ones when viewed as the intensity with respect to the 112 peak which is the strongest line. Although the ratio was about 0.3, in the oxygen-excess type oxide of the present embodiment, it is preferable that these peaks are 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). This value is taken as the peak intensity (diffraction line intensity) of each peak (diffraction line). This value is the peak intensity used in this specification. The ratio of each peak intensity can be obtained by taking this ratio. Here, the half width (FWHM) is read as the full width at the half value of the peak intensity after the background is removed. In addition, what calculated | required ratio of each peak intensity to 112 peak intensity which is the strongest line and each peak intensity may be shown as a relative intensity with respect to 112 peak intensity ("Relative I").

In the above powder X-ray diffraction measurement, all of the following clear peaks (a) to (d) are considered to have diffraction peaks similar to the hexagonal LuBa (Zn, Al) ₄ O ₇ type crystal structure. It means having.
(A) 110 peak (b) 103 peak (c) 112 peak (d) 201 peak

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

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

  The oxygen-excess metal oxide of this embodiment has an excellent oxygen adsorption / desorption capability, and when oxygen is moved up and down in a temperature range of 500 ° C. or less, preferably 200 ° C. to 450 ° C., oxygen is reduced on the low temperature side. Adsorbs (absorbs) and desorbs (releases) oxygen on the high temperature side. In other words, this utilizes the fact that the adsorption rate and the release rate are balanced in the vicinity of 400 ° in the atmosphere. When oxygen is adsorbed and desorbed from the atmosphere and is taken out, typically, oxygen is removed at less than 350 ° C. It can adsorb and release oxygen rapidly in a high temperature range of about 350 to 400 ° C. Unlike a normal oxide, the oxygen-excess metal oxide of this embodiment causes an oxygen release reaction even under a high oxygen concentration. Therefore, by repeating the temperature rise and fall, it is possible to produce a gas having a higher oxygen concentration than in the atmosphere, and conversely, it can be used to lower the oxygen concentration. That is, the oxygen-rich metal oxide of this embodiment has advantageous characteristics as a practical material for oxygen storage or oxygen selective membrane that requires repeated use cycles.

  Further, the oxygen-excess metal oxide of the present embodiment preferably has an oxygen release rate (oxygen desorption rate) of 0.5 wt% / min or more, more preferably 0.7 wt% / min or more. In this specification, the oxygen release rate refers to the weight at the time when no change in weight is caused after standing in nitrogen at 350 ° C. and 1 atm, and then in oxygen at 350 ° C. and 1 atm. When oxygen gas is absorbed until it does not occur, when the atmospheric gas is switched to nitrogen at 350 ° C. and 1 atm, from 1.5 wt% heavier than the reference weight to 0.5 wt% heavier than the reference weight, It means weight change (w% / min) per unit time.

  Furthermore, the oxygen-excess metal oxide of the present embodiment preferably has an oxygen adsorption rate of 0.5 wt% / min or more, more preferably 0.7 wt% / min or more. In the present specification, the oxygen adsorption rate is represented by a change in weight per unit time (w% / min) when performing cycle characteristic evaluation in the examples described later, and the first cycle or the sixth cycle. It means the oxygen adsorption rate of the eye.

Control of the amount of adsorption and desorption of oxygen can be performed by temperature or by partial pressure of oxygen. In the case of temperature, the pressure is not particularly limited, but is usually performed in the range of 0 to 100 atm. Typically, it may be carried out under atmospheric pressure, but it can also be carried out under pressure or under reduced pressure depending on the use conditions. Then, by using the oxygen-excess metal oxide of this embodiment, for example, an oxygen adsorption / desorption device that adsorbs oxygen at less than 350 ° C. and releases oxygen in a high temperature range of about 350 to 400 ° C., or less than 350 ° C. It is possible to realize an oxygen concentrator that adsorbs oxygen and releases oxygen in a high temperature range of about 350 to 400 ° C. to concentrate oxygen.
Next, the 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 higher oxygen partial pressure side, and oxygen is desorbed (released) on the lower side. The optimum oxygen partial pressure for adsorption / desorption depends on the temperature of the oxygen-excess metal oxide during adsorption / desorption. The lower the temperature at the time of adsorption / desorption, there is a tendency to absorb oxygen at a lower oxygen partial pressure, and the higher the temperature, the more the oxygen amount adsorbed tends to decrease even if the oxygen partial pressure is increased. Typically, adsorption may be performed under atmospheric pressure (oxygen partial pressure of 20 kPa), but may be performed under pressurized conditions, and desorption may be performed under an oxygen partial pressure lower than that during adsorption. It can also be done below. In the oxygen-excess metal oxide of this embodiment, the higher the oxygen partial pressure, the more the amount of adsorbed oxygen tends to increase. Therefore, by repeating the oxygen partial pressure level, the gas whose oxygen concentration is higher than in the atmosphere Can also be used to lower the oxygen concentration.
Moreover, you may control by changing both temperature and pressure.

  In addition, the usage aspect of the oxygen excess type metal oxide of this embodiment is not specifically limited. For example, it can be used as a film dispersed in a matrix such as a powder, an aggregate obtained by agglomerating powder or a porous material, a composite material supported on the surface of a carrier, a resin, and the like. Further, the oxygen-excess metal oxide of the present embodiment can be used as oxygen storage ceramics or oxygen selective membrane ceramics.

  Further, by using the above-described oxygen adsorption / desorption principle of the oxygen-excess type metal oxide of this embodiment, an oxygen storage / separation / concentration device for storing, separating and / or concentrating oxygen; an oxidation reaction using the stored oxygen An oxygen concentrating device that performs oxygen enrichment using stored oxygen; a heating device that performs heating using warm heat generated by oxygen storage, separation and / or concentration; oxygen storage, separation and / or Alternatively, it is possible to realize a cooling device that performs cooling using cold heat generated by concentration; a heat exchange device that performs heat exchange using warm heat and / or cold heat generated by oxygen storage, separation, and / or concentration.

  High-concentration oxygen produced using the oxygen-excess metal oxide of this embodiment can be used in various industrial fields. Although there is no particular limitation, for example, when high-concentration oxygen is used, fuel is burned in highly-reactive high-concentration oxygen, and the fuel to be used can increase the combustion temperature and improve the efficiency of a boiler or the like. The total amount of exhaust gas can be reduced, resulting in a reduction in the size and weight of the entire device, leading to improved efficiency and cost reduction, and reducing the accompanying nitrogen gas content, reducing harmful nitrogen oxides, etc. There are advantages.

  The specific application of the high concentration oxygen produced using the oxygen-excess type metal oxide of the present embodiment is not particularly limited, but is used for metalworking burners, various furnace blowing applications (steel making, nonferrous metal melting, etc. ), Water treatment applications (oxygen aeration), Hydrogen sulfide generation suppression applications, Bio-related / Culture / Fermentation applications, Glass processing burner applications, Paper industry applications (Drifting), Oxidation reaction applications, Ozone generator applications (Water treatment, Drifting etc.) ), Combustion equipment applications, internal combustion engine applications such as gasoline and diesel engines, fuel cell applications, aircraft oxygen generation applications, transportation related applications, air conditioner applications such as introducing oxygen-enriched air indoors, and health oxygen gas Applications, medical field applications, live fish breeding applications, food processing applications, gas-filled packaging applications, and the like.

  The method for producing the oxygen-excess type metal oxide of the present embodiment is not particularly limited as long as the stoichiometry and the powder X-ray diffraction pattern described above are obtained. From the viewpoint of obtaining the above-described powder X-ray diffraction pattern with good reproducibility and at low cost, a production method using a low-temperature firing process is preferable. Details will be described below.

As a preferable low-temperature firing process, a method of firing the above-mentioned oxygen-excess metal oxide precursor in a low-oxygen atmosphere having a lower oxygen content than that in the air at a relatively low temperature as compared with the conventional method. Here, as the precursor, one containing at least the oxides of A, D, E and G, carbonate, acetate, citrate, nitrate and / or hydrate thereof can be used. At this time, it is preferable that a precursor contains the oxide, acetate, etc. of A, D, E, and G by the effective molar ratio corresponding to the stoichiometry represented by the said General formula (1). The effective molar ratio here means a molar ratio required for realizing the stoichiometry represented by the general formula (1) after the baking treatment. (Ii) For example, when obtaining an oxygen-excess metal oxide of YBaCo ₄ O _{7 + δ} , the molar ratio of Y: Ba: Co is 1: 1: 4 for the oxide of Y, the carbonate of Ba, and the oxide of Co. (B) A solution of Y acetate, Ba acetate, and Co acetate was mixed so that the molar ratio of Y: Ba: Co was 1: 1: 4. A mixture obtained by calcining an aqueous solution obtained by subjecting the calcined mixture to (c) or an aqueous solution obtained by salt exchange of the aqueous solution with citric acid can be used as a precursor. As another method for producing the precursor, a precipitant such as ammonia or oxalic acid is added to an aqueous nitrate solution containing each desired element to obtain a uniformly mixed precipitate, and the precipitate is calcined. In addition, so-called coprecipitation materials can also be suitably used.

  The treatment temperature in the low-temperature firing process is not particularly limited as long as it is lower than 1050 ° C. which has been conventionally performed. From the viewpoint of efficiently obtaining an oxygen-excess type metal oxide excellent in oxygen adsorption / desorption performance and suppressed in reduction of oxygen adsorption amount by repeated use, it is preferably 700 ° C. or higher and lower than 950 ° C., more preferably 720 ° C. The temperature is 930 ° C. or lower, more preferably 750 ° C. or higher and 900 ° C. or lower. Here, the firing temperature of less than 950 ° C. is a set temperature that is maintained during firing and is a set temperature of the firing furnace. For this reason, even if the temperature is controlled during firing for a short time, even if it exceeds 950 ° C for a short period of time, the temperature is increased by, for example, about 50K for a very short time unless it is extremely excessive. It is intended to be included in the “calcination temperature below 950 ° C.” intended in the form. In addition, the temperature increase rate at the time of baking should just be set suitably in consideration of the characteristic, productivity, etc. of the baking furnace to be used, and is not specifically limited. In general, about 0.5 ° C./min to about 10 ° C./min is a standard. Also, the processing time is not particularly limited. Generally, about 5 to 24 hours is a guide.

The treatment atmosphere in the low-temperature firing process is not particularly limited as long as the oxygen content is a low oxygen atmosphere lower than that in the air. Here, the 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 that substantially does not contain oxygen (the oxygen content is 0% by volume). ). From the viewpoint of efficiently obtaining an oxygen-excess type metal oxide excellent in oxygen adsorption / desorption performance and suppressed in reduction of oxygen adsorption amount by repeated use, the oxygen content is preferably 5% by volume or less, more preferably 3% by volume or less. Further, it is preferably 1% by volume or less, particularly preferably 20 ppm or less. In addition, the minimum of oxygen content is not specifically limited, What is necessary is just 0 volume% or more. Specifically, it is preferable to carry out in an inert gas atmosphere in which the oxygen content is within the above preferred range. Examples of the inert gas include N ₂ gas and Ar gas. Further, the processing pressure is not particularly limited. In general, it may be carried out under normal pressure, but it can also be carried out under pressure or under reduced pressure. In particular, from the viewpoint of preventing the inflow of oxygen from the outside of the furnace, it is preferable to bake under pressure. 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 firing process reaches the highest temperature. After performing the above-described low-temperature firing process, the oxygen-excess metal oxide of this embodiment is obtained by cooling in the air. The oxygen-excess type metal oxide of the present embodiment preferably has a LuBa (Zn, Al) ₄ O ₇ type crystal structure when oxygen is desorbed.

The chemical composition of the obtained oxygen-excess metal oxide can be determined according to a conventional method, for example, iodine titration, ICP emission analysis, or the like. Specifically, the chemical composition of the general formula _A j _B k _C m oxygen excess metal oxide represented by _D n _{O 7 + δ (eg} YBaCo ₄ O _{7 + δ)} can be obtained by the following procedure.
(1) The average valence of Co is determined by the iodine titration method.
(2) The molar ratio of Y, Ba and Co is determined by ICP emission analysis.
(3) From the molar ratio, the values of j, k, m, and n in the equation (1) are normalized 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 determined in consideration of the charge balance.
(5) The chemical composition is determined from the above calculation results.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail, this invention is not limited at all by these Examples. The present invention can adopt various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention. In the following, “part” means “part by mass” unless otherwise specified.

Example 1
As starting materials, Y (CH ₃ COO) ₃ .4H ₂ O, Ba (CH ₃ COO) ₂ , Co (CH ₃ COO) ₂ .4H ₂ O were used in a molar ratio of Y: Ba: Co = 1: 1: 4. Weighed to a ratio. Next, these were dissolved in ultrapure water to prepare an acetate aqueous solution. To the prepared aqueous solution, metal and equimolar citric acid were added, and ammonia water was further added dropwise to adjust the pH to 8. The obtained solution was heated at about 70 ° C. to remove moisture, thereby obtaining a gelled product. The obtained gelled product was calcined in the air at 600 ° C. for 1 hour, and then further pulverized and mixed in an agate mortar. Then, the mixed powder was put in an alumina crucible and calcined for 6 hours under the same conditions to obtain a precursor. The body was made. The obtained precursor was pulverized and mixed, then placed on an alumina boat, set in a highly airtight tube electric furnace, and fired in a nitrogen stream at 900 ° C. for 12 hours. Then, the oxygen-excess metal oxide (YBaCo ₄ O _{7 + δ} ) of Example 1 was obtained by cooling to room temperature while keeping the atmosphere in nitrogen and taking out the treated product from the firing furnace.

(Example 2)
Except for changing the firing time of the processing temperature of 800 ° C. is performed in the same manner as in Example 1 to obtain an oxygen-excess metal oxide of Example 2 _{(YBaCo 4 O 7 + δ)} .

Example 3
Except for changing the firing time of the treatment temperature to 750 ° C. is performed in the same manner as in Example 1 to obtain an oxygen-excess metal oxide of Example 3 _{(YBaCo 4 O 7 + δ)} .

(Comparative Example 1)
As starting materials, Y (CH ₃ COO) ₃ .4H ₂ O, Ba (CH ₃ COO) ₂ , Co (CH ₃ COO) ₂ .4H ₂ O were used in a molar ratio of Y: Ba: Co = 1: 1: 4. Weighed to a ratio. Next, these were dissolved in ultrapure water to prepare an acetate aqueous solution. The produced aqueous solution was heated at about 70 ° C. to remove moisture, thereby obtaining a gelled product. Then, using this gelled product, the oxygen-excess metal oxide (YBaCo ₄ O _{7 + δ} ) of Comparative Example 1 was obtained in the same manner as in Example 1 except that the firing condition was changed to 1050 ° C. in the atmosphere. Obtained.

<Powder X-ray diffraction measurement>
Powder X-ray diffraction measurement of the obtained oxygen-excess metal oxides of Examples 1 to 3 and Comparative Example 1 was performed. FIG. 1 shows a powder X-ray diffraction pattern of each oxygen-excess metal oxide. In FIG. 1, in order from the top, Comparative Example 1 (firing at 1050 ° C. in air), Example 1 (firing at 900 ° C. in a nitrogen gas atmosphere), Example 2 (800 ° C. in a nitrogen gas atmosphere), and Example 3 (nitrogen gas) 2 shows powder X-ray diffraction patterns of 750 ° C. in an atmosphere.
The measurement range was 2θ ranging from 10 ° to 90 °. 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: Rigaku Ultima IV High-speed one-dimensional X-ray detector D / teX included Acceleration voltage: 40kV
Current: 40mA
Kβ cut method: Ni filter

As shown in FIG. 1, in all of Examples 1 to 3 and Comparative Example 1, all diffraction lines having strong intensity are converted into diffraction lines having the same unit cell as hexagonal LuBa (Zn, Al) ₄ O _7. I was able to index. Then, in Comparative Example 1 were atmospheric high temperature firing of the prior art, previously reported _{LuBa (Zn, Al) 4 O} 7 type position and peak intensity of YBaCo ₄ O ₇ and the diffraction lines of the match. The lattice constants were a = 6.2949 cm and c = 10.2407 mm. On the other hand, in Examples 1 to 3 fired at 900 ° C., 800 ° C., and 750 ° C. in a nitrogen stream, the positions of diffraction lines almost coincided with the reported YBaCo ₄ O ₇ , but the peak shapes were greatly different. Specifically, 103, 201, 202, 104, 212, 213, and 205 diffraction lines are particularly noticeably broadened, and the peak intensity of the third strongest 103 diffraction line is greatly increased with the existing YBaCo ₄ O ₇ as a particularly conspicuous feature. It is reduced to about half of 110 diffraction lines. Further, the half width of the 103 diffraction line is 0.3 ° or more, which is about twice the value of 0.15 ° of the comparative example 1 fired at high temperature in the atmosphere. From the above, the oxygen-excess metal oxides of Examples 1 to 3 belong to the hexagonal LuBa (Zn, Al) ₄ O ₇ type structure like the existing YBaCo ₄ O ₇ , but the crystallinity thereof is the existing It was shown to be different from YBaCo ₄ O _{7 of} .
Table 1 shows the intensity (maximum height: arbitrary unit) of each peak, the background intensity, the peak intensity ratio with respect to the 112 peak that is the maximum intensity, and the full width at half maximum of the peak from each XRD measurement result. Example 1-3, which is an oxygen-excess metal oxide of the present invention, compares the half-value width of each peak with the oxygen-excess metal oxide of Comparative Example 1 that is well known in the past. The full width at half maximum of each of the peaks 110, 103, 112, and 201 is sharp from 0.14 ° to 0.16 °, and a crystal with good crystallinity is obtained. On the other hand, the full width at half maximum of the peak of the oxygen-excess type metal oxide of the present invention is a little widened at the peaks of 110 and 112, but the peaks of 103 and 201 are broadened. It can be seen that the half-value width of the 110 peak is less than or equal to ½ of the half-value width of the 103 peak as compared with the half-value width of the 110 peak with little change.

<Measurement of oxygen desorption characteristics>
The oxygen desorption characteristics of the obtained oxygen-excess metal oxides of Examples 1 to 3 and Comparative Example 1 were measured. 2 to 5 are graphs showing thermogravimetric changes when the temperature is raised and lowered in a range of room temperature to 500 ° C. in an oxygen stream. Here, a thermobalance was used, the rate of temperature increase was 2 ° C./min, and the rate of temperature decrease was 2 ° C./min. In any of Examples 1 to 3 and Comparative Example 1, when heated in an oxygen stream, an abrupt weight increase phenomenon accompanying oxygen absorption was confirmed from around 150 to 200 ° C., and when the temperature was further raised, oxygen was increased at around 400 ° C. A sudden weight loss phenomenon due to release was confirmed. On the other hand, when the temperature was lowered from 500 ° C. in the oxygen stream, a sudden weight increase phenomenon due to oxygen reabsorption was observed at around 370 ° C. From these results, it was confirmed that the oxygen-excess metal oxides of Examples 1 to 3 and Comparative Example 1 are substances that exhibit a sudden increase / decrease in weight in the temperature range of 200 to 400 ° C. This behavior is very similar to the oxygen desorption behavior of existing YBaCo ₄ O ₇ . However, Examples 1 to 3 have oxygen adsorption characteristics superior to those of Comparative Example 1 in that the oxygen adsorption start temperature is around 150 ° C. and the rise of oxygen adsorption start at the time of temperature rise is low. confirmed. In addition, this measurement was not performed under practical conditions such as those used in an oxygen adsorption / desorption apparatus, but under experimental conditions where the temperature rising and cooling conditions were 2 ° C./min. Under such experimental conditions, that is, conditions that maintain the equilibrium at that temperature, the oxygen-excess metal oxide of the comparative example known in the art (FIG. 2) is the maximum adsorption of oxygen. The amount is large and the oxygen release capacity seems to be excellent.

<Measurement of oxygen adsorption amount and oxygen release rate>
Next, the oxygen adsorption amount and oxygen release rate of the obtained oxygen-excess metal oxides of Examples 1 to 3 and Comparative Example 1 were measured. Here, the oxygen-excess type metal oxides of Examples 1 to 3 and Comparative Example 1 are held at 350 ° C. in a nitrogen stream (oxygen partial pressure of 0.002 kPa or less), and the gas atmosphere is oxygen (oxygen partial pressure of 101 kPa). The weight change at the time of switching to was measured. 6 to 9 are graphs showing thermogravimetric changes of the oxygen-excess metal oxides of Examples 1 to 3 and Comparative Example 1. FIG. As shown in FIGS. 6 to 9, in any of Examples 1 to 3 and Comparative Example 1, a rapid weight increase accompanying oxygen absorption was shown immediately after gas switching. Here, the big difference was not recognized by Examples 1-3 and the oxygen adsorption rate of the comparative example 1. FIG. At this time, the saturation weight at the time of oxygen adsorption was 3 wt% which was almost the same as that of the existing YBaCo ₄ O ₇ in Comparative Example 1, and 2.0 to 2.5 wt% in Examples 1 to 3. Subsequently, when the gas was switched from oxygen (oxygen partial pressure of 101 kPa) to nitrogen (oxygen partial pressure of 0.002 kPa or less), a rapid weight loss accompanying oxygen release was observed. The oxygen release rate strongly depends on the firing conditions. In Examples 1 to 3 fired at 900 ° C., 800 ° C. and 750 ° C. in a nitrogen stream, 0.71 wt% per minute, 0.92 wt% per minute, 1 per minute 0.07 wt%. This shows that the oxygen release rate of Comparative Example 1 fired at high temperature in the atmosphere is improved by about 2 to 3 times that of 0.38 wt% per minute. It was confirmed that the product has an excellent oxygen releasing ability with an oxygen releasing rate of 0.5 wt% / min or more.

<Change in crystal structure before and after oxygen adsorption / desorption>
Furthermore, the crystal structure before and after oxygen adsorption / desorption was confirmed. Here, the oxygen-excess metal oxide of Example 2 was used, immediately after fabrication (before oxygen adsorption), after annealing at 350 ° C. for 12 hours in an oxygen stream (after oxygen adsorption), and at 350 ° C. for 12 hours in a nitrogen stream. The crystal structure after reannealing (after oxygen desorption) was examined by powder X-ray diffraction measurement. FIG. 10 shows X-ray diffraction patterns. In the figure, in order from the top, immediately after fabrication (before oxygen adsorption), after annealing at 350 ° C. for 12 hours in an oxygen stream (after oxygen adsorption), and after reannealing at 350 ° C. for 12 hours in a nitrogen stream (after oxygen desorption). Each X-ray diffraction pattern is shown, and the lowermost part shows each peak intensity of the X-ray diffraction pattern of the oxygen excess phase YBaCo ₄ O _{8.1 used} as a reference.

As shown in FIG. 10, a clear change was confirmed in the diffraction pattern of 2q = 20 to 40 ° with oxygen adsorption. The position of the diffraction line in the oxygen absorption state is similar to the previously reported oxygen excess phase YBaCo ₄ O _8.1, and the peak of 2q = 31 ° is significantly broadened, but the characteristics before oxygen adsorption are retained. However, it was confirmed that the peak position shifted to the lower angle side due to oxygen absorption and that some peaks were split. This suggests that the phase changed to an oxygen excess phase (YBaCo ₄ O _{7 + δ} ) with oxygen absorption. On the other hand, a clear change was confirmed in the diffraction pattern of 2q = 20-40 ° with oxygen desorption. The diffraction pattern of 2q = 20 to 40 ° after oxygen desorption almost completely coincided with the diffraction pattern before oxygen adsorption, and the peak of 103 remained broad. This suggests that the phase changed to the original phase (YBaCo ₄ O ₇ ) with oxygen desorption. From the above, oxygen adsorption / desorption is caused by the phase change of the oxygen-excess metal oxide, and the characteristics of the crystal structure are maintained before and after oxygen adsorption / desorption, and oxygen adsorption / desorption is performed reversibly. It has been shown.

<Evaluation of cycle characteristics>
Next, the cycle characteristics of the obtained oxygen-excess metal oxides of Examples 1 to 3 and Comparative Example 1 were evaluated by TG thermogravimetry. The results are shown in FIGS. Here, after maintaining the temperature in the air (oxygen concentration 21%) at a temperature of 470 ° C. and making the weight change not substantially occurred (a state in which oxygen is completely released), the temperature is decreased from 470 ° C. to 230 ° C. in 7 minutes, The temperature was raised from 230 ° C. to 470 ° C. in 5 minutes three times (hereinafter also referred to as “the first three cycles”), kept at 470-480 ° C. for 9 minutes to release oxygen, and then again 470 ° C. The temperature was lowered from 230 ° C. in 7 minutes and the temperature was raised from 230 ° C. to 470 ° C. in 5 minutes 3 times (hereinafter also referred to as “the latter three cycles”). The measurement interval of temperature and weight was performed every second. The weight change accompanying oxygen adsorption / desorption at that time was measured. 11 to 14, the temperature change is indicated by a dotted line, and the weight change is indicated by a solid line.

  As shown in FIG. 11, the change in the weight of the oxygen-excess metal oxide of Comparative Example 1 was about 1.5 wt% in the first three cycles, but 1.3 wt% in the latter three cycles. It was found that the maximum oxygen adsorption amount decreased as the number of cycles increased. It was also found that the followability (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. 12 to 14, the weight change of the oxygen-excess metal oxides of Examples 1 to 3 is as large as 2.3 wt% or more throughout the entire cycle, and the maximum oxygen with the increase in the number of cycles. No decrease in the amount of adsorption was observed. Furthermore, it was found that the temperature swing during oxygen adsorption (responsiveness) was good (responsiveness) and the oxygen adsorption rate was high. From the above, it is confirmed that the oxygen-excess metal oxides of Examples 1 to 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. It was done.

Table 2 shows the temperatures at which the oxygen adsorption in Examples 1 to 3 and Comparative Example 1 shift from release to release in the above-described cycle characteristic evaluation.

  From this result, it can be seen that the oxygen-excess metal oxide of the present invention can release oxygen at a lower temperature, that is, at an earlier stage than the conventional one (comparative oxide).

Table 3 shows the maximum adsorption amount of oxygen in each cycle, its average, and the difference between the first and sixth oxygen maximum adsorption amounts.

  From this result, it was found that the oxygen-excess type metal oxide of the present invention has a very small difference of 0.1 wt% or less when the adsorption / desorption in a short time is repeated 6 times. In particular, in Examples 2 and 3, it was found that the difference in maximum adsorption amount was remarkably excellent at 0.05 wt% or less. Compared with the comparative example 1 of the conventional product in which the maximum adsorption amount is reduced by 0.2 wt% or more, the oxygen-excess metal oxide of the present invention has a particularly low oxygen adsorption amount in a repeated cycle. It turns out that it was suppressed. Further, when the absolute value of the maximum adsorption amount is compared, when oxygen adsorption / desorption is performed under the test conditions, the oxygen-excess metal oxide of the present invention is about 1.5% compared to Comparative Example 1 of the conventional product. It can be seen that the oxygen adsorption amount is doubled. This means that the size and weight can be reduced to 2/3 when the apparatus is configured using the oxygen-excess metal oxide of the present invention, which is a very significant 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 Examples 1 to 3 and Comparative Example 1, but data in which the difference is particularly prominent is shown. The comparison will be described focusing on the oxygen adsorption rate when the oxygen adsorption amount is changed from 1 wt% to 1.5 wt%. In Comparative Example 1, 1.5 wt% was not reached in the fifth and sixth cycles, and therefore Comparative Example 1 was compared only with the oxygen adsorption rate during the first cycle.

  The oxygen adsorption rate in the first cycle was 0.9 wt% / min in Example 1, 1.1 wt% / min in Example 2, 1.2 wt% / min in Example 3, and Comparative Example 1 Was 0.2 wt% / min. On the other hand, the oxygen adsorption rate at the sixth cycle is 0.9 wt% / min in Example 1, 1.2 wt% / min in Example 2, and 1.3 wt% / min in Example 3, and There was almost no change in speed from the sixth cycle. From this, the oxygen-excess metal oxide of the present invention has an oxygen adsorption rate of 0.5 wt% / min or more, more preferably 0 when the oxygen adsorption amount is changed from 1 wt% to 1.5 wt% under the test conditions. It can be seen that it is 7 wt% / min or more. At the same time, the oxygen-excess metal oxide of the present invention is 1.5 wt% or more, more preferably 1.7 wt% or more, and most preferably 2 wt% or more, even if repeated adsorption and desorption of oxygen is repeated under the present test conditions. It can be seen that it exhibits oxygen adsorption ability.

  Similarly, the oxygen adsorption rates from 0.5 wt% to 1 wt% are all 0.9 wt% / min from the first cycle to the sixth cycle in Examples 1 to 3, whereas the oxygen adsorption rate from Comparative Example 1 is all 0. It was 3 wt% / min. Therefore, even with the oxygen adsorption rate from 0.5 wt% to 1 wt%, the oxygen-excess metal oxide of the present invention has an oxygen adsorption rate of 0.5 wt% / min or more, more preferably 0.7 wt% / min or more. It turns out that it is.

  The oxygen-excess metal oxide of the present invention is excellent in oxygen adsorption / desorption capability, has a very high oxygen adsorption / desorption rate, and further has high durability during repeated use. Therefore, oxygen storage that requires repeated use cycles is required. It can be used widely and effectively as a material for practical use for oxygen, oxygen concentration, oxygen separation or oxygen selective membrane. Moreover, since the oxygen adsorption / desorption capability is enhanced as compared with the conventional one, it contributes to miniaturization and energy saving in these applications. Furthermore, since it is a material that operates in a relatively low temperature range, it is particularly useful as a practical material for cold districts, such as a three-way catalyst for a fuel cell or an exhaust gas purification device of an automobile.

Claims (17)

The following general formula (1):
A _j D _k E _m G _n O _{7 + δ} (1)
(Where
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,
E and G are each independently one or more selected from oxygen tetracoordinate elements, and at least one is a transition metal element,
j> 0, k> 0, and independently m ≧ 0 and n ≧ 0, provided that j + k + m + n = 6 and 0 <δ ≦ 1.5. )
In the powder X-ray diffraction measurement, the peak intensity of 103 of the hexagonal crystal structure is smaller than the peak intensity of 110, and the half width (FWHM) of the peak of 103 is 0.3. An oxygen-excess metal oxide that is at least ° C. The weight at the time of no change in weight after standing in nitrogen at 350 ° C. at 1 atm is taken as the reference weight, and then the oxygen is absorbed in oxygen at 350 ° C. at 1 atm until no change in weight occurs. When the gas is switched to nitrogen at 350 ° C. and 1 atm, the oxygen release rate until it decreases from 1.5 wt% heavier than the reference weight to 0.5 wt% heavier than the reference weight is 0.5 wt% / min or more. Is,
The oxygen-excess metal oxide according to claim 1. A in the general formula (1) includes Y,
The oxygen-excess metal oxide according to claim 1 or 2. D in the general formula (1) contains Ba,
The oxygen excess type metal oxide as described in any one of Claims 1-3. E in the general formula (1) contains Co,
The oxygen excess type metal oxide as described in any one of Claims 1-4. In powder X-ray diffraction measurement, it has a LuBa (Zn, Al) ₄ O ₇ type crystal structure characterized by a diffraction pattern having all of the following (a) to (d):
(A) 110 peak (b) 103 peak (c) 112 peak (d) 201 peak (b) The peak intensity is smaller than the peak intensity of (a), and the half width of (a) is It is 1/2 or less of the half value width of (b), and the half value width of (b) is 0.3 ° or more.
The oxygen-excess type metal oxide according to any one of claims 1 to 5. Using the oxygen-excess metal oxide according to any one of claims 1 to 6,
Oxygen adsorption / desorption device. Oxygen is adsorbed on the oxygen-excess metal oxide below 350 ° C., and oxygen is released from the oxygen-excess metal oxide above 350 ° C.
The oxygen adsorption / desorption device according to claim 7. At 200 ° C. or more and 400 ° C. or less, oxygen is adsorbed on the oxygen-excess type metal oxide in the presence of oxygen, and oxygen is released from the oxygen-excess type metal oxide under a pressure where the oxygen partial pressure is lower than that during oxygen adsorption.
The oxygen adsorption / desorption device according to claim 7. Using the oxygen-excess metal oxide according to any one of claims 1 to 6,
An oxygen concentrator for concentrating oxygen by adsorbing oxygen to the oxygen-excess metal oxide at less than 350 ° C. and releasing oxygen from the oxygen-excess metal oxide at 350 ° C. or higher. Using the oxygen-excess metal oxide according to any one of claims 1 to 6,
Oxygen is adsorbed on the oxygen-excess metal oxide in the presence of oxygen at a temperature of 200 ° C. or more and 400 ° C. or less, and oxygen is released from the oxygen-excess metal oxide under a pressure lower than the oxygen adsorption pressure. Oxygen concentrator for concentrating oxygen. Calcining a precursor of an oxygen-excess type metal oxide at a temperature of 700 ° C. or higher and lower than 950 ° C. in a low oxygen atmosphere having an oxygen content lower than that in the air;
The following general formula (1):
A _j D _k E _m G _n O _{7 + δ} (1)
(Where
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,
E and G are each independently one or more selected from oxygen tetracoordinate elements, and at least one is a transition metal element,
j> 0, k> 0, and independently m ≧ 0 and n ≧ 0, provided that j + k + m + n = 6 and 0 <δ ≦ 1.5. )
The manufacturing method of the oxygen excess type metal oxide which has at least stoichiometry represented by these. The oxygen-excess metal oxide having at least stoichiometry represented by the general formula (1) has a peak intensity of 103 having a hexagonal crystal structure smaller than a peak intensity of 110 in powder X-ray diffraction measurement, and 103 The peak half-value width is 0.3 ° or more,
The manufacturing method of the oxygen excess type metal oxide of Claim 12. The oxygen-excess metal oxide having at least stoichiometry represented by the general formula (1) is characterized by LuBa characterized by a diffraction pattern having all of the following (a) to (d) in powder X-ray diffraction measurement: (Zn, Al) ₄ O ₇ type crystal structure,
(A) 110 peak (b) 103 peak (c) 112 peak (d) 201 peak (b) The peak intensity is smaller than the peak intensity of (a), and the half width of (a) is It is 1/2 or less of the half value width of (b), and the half value width of (b) is 0.3 ° or more.
The method for producing an oxygen-rich metal oxide according to claim 12 or 13. Firing in an atmosphere having an oxygen content of 5% by volume or less,
The manufacturing method of the oxygen excess type metal oxide as described in any one of Claims 12-14. In the effective molar ratio corresponding to the stoichiometry represented by the general formula (1), the oxides, carbonates, acetates, citrates, nitrates and / or waters of the A, D, E and G Made from a precursor containing at least a Japanese product,
The manufacturing method of the oxygen excess type metal oxide as described in any one of Claims 12-15. Y, Ba and Co are contained in a stoichiometric ratio of at least 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) ₄ O ₇ type crystal structure characterized by a diffraction pattern having all of the following (a) to (d):
(A) 110 peak (b) 103 peak (c) 112 peak (d) 201 peak (b) The peak intensity is smaller than the peak intensity of (a), and the half width of (a) is It is 1/2 or less of the half value width of (b), and the half value width of (b) is 0.3 ° or more.
Oxygen-rich metal oxide.

Images