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Electron or hydride ion intake/release material, electron or hydride ion intake/release composition, transition metal-supported material and catalyst, and use in relation thereto

Foreign code F210010545
File No. K20203WO
Posted date 2021年8月2日
Country アメリカ合衆国
Application number 201916980166
Gazette No. 20210002142
Date of filing 平成31年3月13日(2019.3.13)
Gazette Date 令和3年1月7日(2021.1.7)
International application number JP2019010175
International publication number WO2019176987
Date of international filing 平成31年3月13日(2019.3.13)
Date of international publication 令和元年9月19日(2019.9.19)
Priority data
  • 特願2018-046846 (2018.3.14) JP
  • 2019JP10175 (2019.3.13) WO
Title Electron or hydride ion intake/release material, electron or hydride ion intake/release composition, transition metal-supported material and catalyst, and use in relation thereto
Abstract The present invention is to provide an electron or hydride ion intake/release material comprising a lanthanoid oxyhydride represented by the formula Ln(HO) (in the formula, Ln represents a lanthanoid element) or an electron or hydride ion intake/release composition comprising at least one kind of lanthanoid oxyhydride; a transition metal-supported material wherein a transition metal is supported by the above electron or hydride ion intake/release material or electron or hydride ion intake/release composition; and a catalyst comprising the transition metal-supported material. The electron or hydride ion intake/release material or electron or hydride ion intake/release composition according to the present invention has a higher ability for intake/release of electron or hydride ion than that of a conventional hydride-containing compound, and can be used effectively as a catalyst such as a catalyst having excellent ammonia synthesis activity by supporting a transition metal thereon.
Outline of related art and contending technology BACKGROUND ART
Ammonia synthesis is one of the fundamental processes in chemical industries, and a Haber-Bosch method, which uses an iron oxide as a catalyst and potassium hydroxide as a promoter, has been widespread, and this method has not been largely changed for around 100 years. In the ammonia synthesis by the Haber-Bosch method, the synthesis is performed by reacting nitrogen gas with hydrogen gas on a catalyst under a high temperature of 300° C. to 500° C. and a high pressure of 20 to 40 MPa. The reaction for synthesizing ammonia by using a gas containing hydrogen and nitrogen as the raw material is represented by N2+3H2 4↔2NH3. However, since this reaction is an exothermic reaction, the lower the temperature is, the better it is to shift the equilibrium to the right, but since the number of molecules is decreased by the reaction, the higher the pressure is, the better it is to shift the equilibrium to the right.
However, since the nitrogen molecule has an extremely strong triple bond between the nitrogen atoms, the reactivity is extremely poor, and the reaction between nitrogen and hydrogen is extremely slow. Accordingly, it has been extremely important to develop a catalyst that can break the triple bond of the nitrogen molecule and activate the nitrogen molecule. Haber et al. have used an iron ore as a catalyst, but this iron ore contains an iron oxide as a main component and also contains alumina and potassium oxide. In the Haber-Bosch method, an iron oxide is packed in a reaction device as a catalyst, but what actually reacts is metal iron generated by reduction with hydrogen. Alumina functions as a support without being reduced and prevents iron particles from being sintered, and potassium oxide donates electrons to iron particles as a base to enhance the catalytic ability. Because of these actions, it is called “doubly promoted iron catalyst”. However, even if this iron catalyst is used, the reaction rate is insufficient at a low temperature of 400° C. or less.
In a conventional industrial technique, hydrogen is produced by reforming natural gas or the like, the hydrogen is reacted with nitrogen in the air under the above-described conditions in the same plant, and ammonia is synthesized. As the catalyst for ammonia synthesis, conventionally, Fe/Fe3O4 has been mainly used, but in recent years, an Fe/C or Ru/C catalyst using activated carbon as a support has been also used.
It is known that when metal catalyst particles for ammonia synthesis are formed by supporting Ru on a support and ammonia synthesis is performed by using the metal catalyst particles, the reaction proceeds at a low pressure, and thus such a catalyst has attracted attention as a second-generation catalyst for ammonia synthesis. However, the catalytic activity of Ru as a single substance is extremely small, and in order to exert the ability to break the triple bond of a nitrogen molecule and convert the nitrogen molecule to adsorbed nitrogen atoms on a Ru metal catalyst particle, it is preferred to simultaneously use a material having a high electron donating property, and it is better to use a support including a basic material in place of Fe3O4 or activated carbon, or to use a promoter compound such as an alkali metal, an alkali metal compound, or an alkaline earth metal compound.
On the other hand, a titanium-containing oxide having a perovskite-type crystal structure or a layered perovskite-type crystal structure, represented by MTiO3 (M represents Ca, Ba, Mg, Sr, or Pb), a titanium-containing oxide in which some of the Ti atoms are replaced with at least one kind of Hf and Zr, and the like (collectively referred to as “titanium-containing perovskite-type oxide”) each have an extremely high relative dielectric constant, and therefore, have been actively studied for a long period of time as a device such as a capacitor material, or a dielectric film, and also from the viewpoint of, for example, the application to a substrate material of other perovskite-type transition metal oxides, and a non-linear resistor.
In Patent Literature 1, synthesis of a titanate oxyhydride based on the formula ATi (O, H)3 (A represents Ca2+, Sr2+, or Ba2+) has been reported, and this oxyhydride is a compound in which hydrogen is allowed to coexist as hydride (H-) with oxide ion (O2-), and is prepared by a method for reducing a precursor ATiO3 to a topochemical with a metal hydride such as CaH2, LiH, or NaH (in this regard, the expression “topochemical” means that the molecular structure of a resulting material is governed by the crystal structure before the reaction). This oxyhydride is characterized by having hydride ion-electron mixed conductivity, hydrogen storage, and release performance (that is, an ability for intake/release of electron or an ability for intake/release of hydride ion).
Patent Literature 2 has disclosed that when a catalyst is formed by using a titanium-containing perovskite-type oxyhydride in which hydride (H-) has contained, as a support and supporting a metal exhibiting catalytic activity such as Ru or Fe on the support, the ammonia synthesis activity is dramatically improved due to the unique effect of hydride (H-), the catalyst is stable also in a reaction for a long period of time without using an alkali metal or an alkaline earth metal, or a compound thereof, which is unstable, as a promoter compound, and thus, the catalyst becomes an ammonia synthesis catalyst having significantly higher activity as compared with the conventional catalyst known to have the highest activity, and highly efficient ammonia synthesis at a low pressure of less than 20 MPa can be realized. Further, Patent Literature 2 has disclosed that when a Ti-containing perovskite-type oxyhydride is heated to a low temperature of 400 to 600° C. in an ammonia gas or N2/H2 mixed air flow, nitride ions are introduced through a process of H/N exchange between hydride (H) and nitrogen (N), and BaTi(O, H, N)3 is formed.
Scope of claims [claim1]
1. An electron or hydride ion intake/release material, comprising a lanthanoid oxyhydride represented by the following formula (1):
[Chemical formula 1]
Ln(HO)  (1)
wherein Ln represents a lanthanoid element.

[claim2]
2. The electron or hydride ion intake/release material according to claim 1, wherein
the lanthanoid oxyhydride has a structure in which a hydride ion (H-) and an oxide ion (O2-) coexist as a HO-ordered type or a HO-solid solution type together with a lanthanoid as a component of a crystal lattice.

[claim3]
3. The electron or hydride ion intake/release material according to claim 1, wherein
the lanthanoid oxyhydride has a structure in which a hydride ion (H-) and an oxide ion (O2-) coexist as a HO-solid solution type together with a lanthanoid as a component of a crystal lattice.

[claim4]
4. An electron or hydride ion intake/release composition, comprising at least one kind of lanthanoid oxyhydride.

[claim5]
5. The electron or hydride ion intake/release composition according to claim 4, wherein
a lanthanoid element contained in the lanthanoid oxyhydride is at least one kind selected from the group consisting of Gd, Sm, Pr, and Er.

[claim6]
6. The electron or hydride ion intake/release composition according to claim 4, wherein
a lanthanoid element contained in the lanthanoid oxyhydride is at least one kind selected from the group consisting of Gd, Sm, and Er.

[claim7]
7. The electron or hydride ion intake/release composition according to claim 4, wherein
the lanthanoid oxyhydride is represented by the following formula (2):
[Chemical formula 2]
LnH(x)O((3-x)/2) (0<x<3)  (2)
wherein Ln represents a lanthanoid element.

[claim8]
8. The electron or hydride ion intake/release composition according to claim 7, wherein
Ln in the above formula (2) is at least one kind selected from the group consisting of Gd, Sm, Pr, and Er.

[claim9]
9. The electron or hydride ion intake/release composition according to claim 7, wherein
Ln in the above formula (2) is at least one kind selected from the group consisting of Gd, Sm, and Er.

[claim10]
10. The electron or hydride ion intake/release composition according to claim 4, wherein
the lanthanoid oxyhydride has at least one kind of crystal structure selected from the group consisting of an ordered fluorite-type structure (P4/nmm), a PbCl2-type structure (Pnma), and an Fe2P-type structure (P62m).

[claim11]
11. The electron or hydride ion intake/release composition according to claim 4, wherein
the lanthanoid oxyhydride is a lanthanoid oxyhydride having a crystal structure obtained by heating a lanthanoid oxide and a lanthanoid hydride under a pressure of at least 2 GPa or more in the absence of gas.

[claim12]
12. A transition metal-supported material, comprising:
a transition metal supported by the electron or hydride ion intake/release material or electron or hydride ion intake/release composition of claim 1, wherein
the transition metal excludes a lanthanoid element.

[claim13]
13. The transition metal-supported material according to claim 12, wherein
the transition metal is at least one kind selected from the group consisting of Ru, Fe, Co, Cr, and Mn.

[claim14]
14. A catalyst, comprising
the transition metal-supported material according to claim 12.

[claim15]
15. The catalyst according to claim 14, which has hydrogen reduction activity.

[claim16]
16. The catalyst according to claim 14, which has ammonia synthesis activity.

[claim17]
17. A method for producing a lanthanoid oxyhydride for use as an electron or hydride ion intake/release material, the method comprising the steps of:
(1) mixing a lanthanoid oxide and a metal hydride (with the proviso that a lanthanoid hydride is excluded);
(2) heating the obtained mixture under atmospheric pressure or more in the absence of gas or in the presence of hydrogen gas or an inert gas; and
(3) washing and removing a by-product metal oxide and an unreacted metal hydride, if necessary, after the above heating step.

[claim18]
18. A method for producing a lanthanoid oxyhydride for use as an electron or hydride ion intake/release material, the method comprising the steps of:
(1) mixing a lanthanoid oxide and a lanthanoid hydride; and
(2) heating the obtained mixture under a pressure of at least 2 GPa or more in the absence of gas.

[claim19]
19. The method according to claim 17, wherein
a heating temperature is 400 to 900° C. and a heating time is 12 to 72 hours, in the above heating step.

[claim20]
20. A method for producing a transition metal-supported material for use as a catalyst, the method comprising the steps of:
(1) mixing a lanthanoid oxide and a metal hydride (with the proviso that a lanthanoid hydride is excluded);
(2) heating the obtained mixture under atmospheric pressure or more in the absence of gas or in the presence of hydrogen gas or an inert gas;
(3) washing and removing a by-product metal oxide and an unreacted metal hydride, if necessary, after the above heating step; and
(4) supporting a transition metal on the obtained lanthanoid oxyhydride by an impregnation method,
wherein the transition metal excludes a lanthanoid element.

[claim21]
21. A method for producing a transition metal-supported material for use as a catalyst, the method comprising the steps of:
(1) mixing a lanthanoid oxide and a lanthanoid hydride;
(2) heating the obtained mixture under a pressure of at least 2 GPa or more in the absence of gas; and
(3) supporting a transition metal on the obtained lanthanoid oxyhydride by an impregnation method,
wherein the transition metal excludes a lanthanoid element.

[claim22]
22. The method according to claim 20, wherein
the impregnation method comprises the steps of:
(A) dispersing the lanthanoid oxyhydride in a solution prepared by dissolving a transition metal compound in a solvent, and then evaporating the solvent to obtain a supported material precursor; and
(B) heating the obtained supported material precursor in a reducing atmosphere to obtain a transition metal-supported material in which a transition metal in the transition metal compound is supported by the oxyhydride as a nano-metal particle.

[claim23]
23. The method according to claim 22, wherein
a heating temperature is 100 to 700° C. and a heating time is 1 to 5 hours, in heating the supported material precursor in the impregnation method.

[claim24]
24. A method for producing ammonia, comprising the steps of:
supplying a gas containing hydrogen and nitrogen as a raw material so that the gas comes into contact with the transition metal-supported material of claim 12, or a catalyst comprising the transition metal-supported material; and
synthesizing ammonia by heating the transition metal-supported material or catalyst under an atmosphere of the gas.

[claim25]
25. The method for producing ammonia according to claim 24, wherein
a mixing mole ratio of nitrogen to hydrogen in the gas is around 1/10 to 1/1, a reaction temperature in the step of synthesizing ammonia is room temperature to less than 500° C., and a reaction pressure in the step of synthesizing ammonia is 10 kPa to 20 M Pa.

[claim26]
26. The method for producing ammonia according to claim 24, wherein
the atmosphere of the gas in the step of synthesizing ammonia is an atmosphere of a water vapor partial pressure of 0.1 kPa or less.

[claim27]
27. The method for producing ammonia according to claim 24, further comprising the step of:
removing an oxide attached onto a surface of the transition metal-supported material or catalyst by reducing the transition metal-supported material with hydrogen gas or a mixed gas of hydrogen and nitrogen, before supplying a gas containing hydrogen and nitrogen as a raw material.
  • Inventor, and Inventor/Applicant
  • KOBAYASHI YOJI
  • KAGEYAMA HIROSHI
  • YAMASHITA HIROKI
  • BROUX THIBAULT
  • JAPAN SCIENCE AND TECHNOLOGY AGENCY
IPC(International Patent Classification)
Reference ( R and D project ) PRESTO Innovative Nano-electronics through Interdisciplinary Collaboration among Material, Device and System Layers AREA
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