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Composite Oxide, Metal-Supported Material, and Ammonia Synthesis Catalyst meetings

Foreign code F210010325
File No. AF40-03WO
Posted date Feb 1, 2021
Country United States of America
Application number 201816648951
Gazette No. 20200247682
Date of filing Sep 18, 2018
Gazette Date Aug 6, 2020
International application number JP2018034515
International publication number WO2019059190
Date of international filing Sep 18, 2018
Date of international publication Mar 28, 2019
Priority data
  • P2017-183215 (Sep 25, 2017) JP
  • P2018-089516 (May 7, 2018) JP
  • 2018JP34515 (Sep 18, 2018) WO
Title Composite Oxide, Metal-Supported Material, and Ammonia Synthesis Catalyst meetings
Abstract A composite having a composition expressed by AnXyMm wherein, A represents a lanthanoid that is in a trivalent state at least partially or entirely, X represents an element that is a Group-2 element in the periodic table selected from the group consisting of Ca, Sr, and Ba, or a lanthanoid that is different from A, M represents an element that is a Group-1 element in the periodic table, a Group-2 element selected from the group consisting of Ca, Sr, and Ba, or a lanthanoid that is different from A and X, n satisfies 0<n<1, y satisfies 0<y<1, m satisfies 0≤m<1, and n+y+m=1.
Outline of related art and contending technology BACKGROUND ART
Ammonia is an important raw material in the current chemical industry. Of the produced ammonia, 80% or more is consumed to manufacture chemical fertilizers for farming. Moreover, ammonia has attracted attention as a carrier for energy and hydrogen. This is because (1) the hydrogen content is high (17.6 wt %), (2) the energy density is high (12.8 GJ/m3), and (3) carbon dioxide is not generated when ammonia is decomposed to manufacture hydrogen. When ammonia can be efficiently manufactured from renewable energy such as solar energy or wind power, problems on the global scale regarding energy and a food crisis can be reduced.
In the Haber-Bosch process that has been used to manufacture ammonia, a large amount of energy is consumed and this consumption constitutes about 1 to 2% of the energy consumption in the world. In this process, about 60% of the consumption energy is recovered and secured as the enthalpy of ammonia. However, a large part of the remaining energy is lost when hydrogen is manufactured from natural gas, ammonia is synthesized, or gas is separated. In the Haber-Bosch process, ammonia is synthesized at very high temperature (>450° C.) and high pressure (>20 MPa); thus, reduction of energy that is used in large quantity in this process has been highly required. In order to suppress the energy consumption on the global level, it has been necessary to obtain a catalyst that can synthesize ammonia under a milder condition (lower temperature and lower pressure) than that for an iron-based catalyst that is used in the Haber-Bosch process.
In recent years, a method of manufacturing ammonia at pressure as low as 1 MPa (10 atm) has been known. A ruthenium catalyst that is used in the manufacture of ammonia is usually supported by a carrier. For example, Patent Literature 1 has disclosed that when rare earth oxide is used as a carrier that supports ruthenium, the usage of ruthenium can be reduced and the reaction temperature can be reduced. In the manufacturing method for ammonia according to Patent Literature 1, however, the ammonia yield in the case where ammonia is manufactured at lower pressure has been insufficient.
Other than Patent Literature 1, various patent literatures have disclosed ammonia synthesis catalysts having ruthenium supported by various rare earth oxide carriers. Typical examples thereof are disclosed in Patent Literatures 2 to 4 and Non-Patent Literature 1. Patent Literature 2 and Patent Literature 4 have disclosed lanthanoid oxide as the carrier, Patent Literature 3 has disclosed praseodymium oxide as the carrier, and Non-Patent Literature 1 has disclosed Ce oxide as the carrier. Non-Patent Literature 2 has disclosed a catalyst of Ru/CeO2—La2O3 that is manufactured by co-precipitating a hydroxide of Ru, Ce, and La and drying and activating the co-precipitated product.
The literatures disclosing the conventional techniques including Patent Literatures 1, 2, and 4 and Non-Patent Literature 1 describe that the ruthenium catalyst used in the ammonia synthesis includes Ru as particles on a carrier surface thereof. There is a report that, in the case where Ru exists as the particles, the average diameter thereof is more than 5 nm (see Non-Patent Literature 2). In addition, Patent Literature 3 describes that Ru has an egg shell structure.
A synthesis catalyst is generally required to have high synthesis activity. Regarding the ruthenium catalyst for the ammonia synthesis, which is currently in the development, the ruthenium catalyst with high activity that can achieve higher yield has continuously been required.
Moreover, since it is necessary that a synthesis reactor is filled with the catalyst and the catalyst is regularly exchanged, the handling needs to be easy. Regarding the ruthenium catalyst for the ammonia synthesis, the easier handling has also been required.
Scope of claims [claim1]
1. A composite oxide comprising a metal element expressed by a composition of General Formula (1):
AnXyMm  (1)
wherein,
A represents a lanthanoid that is in a trivalent state at least partially or entirely,
X represents an element that is a Group-2 element in the periodic table selected from the group consisting of Ca, Sr, and Ba, or a lanthanoid that is different from A,
M represents an element that is a Group-1 element in the periodic table, a Group-2 element selected from the group consisting of Ca, Sr, and Ba, or a lanthanoid that is different from A and X,
n satisfies 0<n<1,
y satisfies 0<y<1,
m satisfies 0≤m<1, and
n+y+m=1.

[claim2]
2. The composite oxide according to claim 1, wherein a ratio (A3+/Atotal) of a number of moles of the element A in the trivalent state (A3+) to a total number of moles of the element A (Atotal) satisfies 0.1≤A3+/Atotal≤1.0.

[claim3]
3. The composite oxide according to claim 1, wherein the composite oxide includes a solid solution that is a tetragonal crystal or a cubic crystal.

[claim4]
4. The composite oxide according to claim 1, wherein at least one of the elements A, X, and M in the composite oxide is an element with strong basicity in which a value of a partial negative charge (-δO) of oxygen in an oxide state is 0.50 or more.

[claim5]
5. The composite oxide according to claim 1, wherein when a composition ratio of each element (i) in the composite oxide is ni, a Sanderson electronegativity of each element is χi and a value of a partial negative charge (-δO) of oxygen expressed by the following Formula (A) is 0.52 or more.

[claim6]
6. The composite oxide according to claim 1, wherein
General Formula (1) is a binary composite oxide expressed by the following General Formula (1-1):
AnXy  (1-1)
wherein
A represents a lanthanoid that is in a trivalent state at least partially or entirely,
X represents an element that is a Group-2 element in the periodic table selected from the group consisting of Ca, Sr, and Ba, or a lanthanoid that is different from A,
n satisfies 0<n<1,
y satisfies 0<y<1, and
n+y=1, and
the composite oxide is a solid solution of A and X.

[claim7]
7. The composite oxide according to claim 1, wherein
General Formula (1) is a ternary composite oxide expressed by the following General Formula (1-2):
AnXyMm  (1-2)
wherein
A represents a lanthanoid that is in a trivalent state at least partially or entirely,
X represents an element that is a Group-2 element in the periodic table selected from the group consisting of Ca, Sr, and Ba, or a lanthanoid that is different from A,
M represents an element that is a Group-1 element in the periodic table, a Group-2 element selected from the group consisting of Ca, Sr, and Ba, or a lanthanoid that is different from A and X,
n satisfies 0<n<1,
y satisfies 0<y<1,
m satisfies 0≤m<1, and
n+y+m=1, and
the composite oxide is in a mixed state in which a solid solution of A and an oxide of one of X and M, and an oxide of the other of X and M are mixed.

[claim8]
8. The composite oxide according to claim 1, wherein
X in General Formula (1) is Ba and a quantity of carbonate ions included in the composite oxide is 10 mol % or less of Ba.

[claim9]
9. A composite oxide expressed by the following General Formula (2):
AnX1-nMmOx  (2)
wherein,
A represents a rare earth element that is in a trivalent state at least partially,
X represents an element that is a Group-2 element in the periodic table, a Group-4 element, or a rare earth element that is different from A,
M represents an element that is a Group-2 element in the periodic table, a Group-4 element, or a rare earth element that is different from A and X,
n satisfies 0<n<1,
m satisfies 0≤m<0.5, and
x represents the number of oxygen atoms necessary for the composite oxide to keep neutral electrically.

[claim10]
10. A metal-supported material in which transition metal excluding Group-4 elements is supported by the composite oxide according to claim 1.

[claim11]
11. The metal-supported material according to claim 10, wherein a ratio of a value (Dads) of a Ru dispersion degree obtained by an H2 pulse chemical adsorption method to a value (DTEM) of a Ru dispersion degree expected from an average particle diameter of Ru particles obtained from a TEM image satisfies 0<Dads/DTEM<1.

[claim12]
12. The metal-supported material according to claim 10, wherein when nitrogen is adsorbed on the supported transition metal, N≡N stretching vibration υ1 of nitrogen molecules that mutually act in a major-axis direction is observed in 2300 to 2000 cm-1 by an infrared absorption spectroscopy, and/or weakened N≡N stretching vibration υ2 of the nitrogen molecules that mutually act in the major-axis direction for the transition metal is observed in 1900 to 1500 cm-1.

[claim13]
13. The metal-supported material according to claim 10, wherein an average particle diameter of the transition metal supported on the composite oxide is 100 nm or less.

[claim14]
14. An ammonia synthesis catalyst comprising the metal-supported material according to claim 10.

[claim15]
15. A manufacturing method for the composite oxide according to claim 1, the manufacturing method comprising:
mixing an A precursor including A, an X precursor including X, and an M precursor including M to obtain a mixture; and
calcinating the mixture at 600° C. or more.

[claim16]
16. A manufacturing method for the metal-supported material according to claim 10, the manufacturing method comprising:
mixing an A precursor including A, an X precursor including X, and an M precursor including M to obtain a mixture;
calcinating the mixture at 600° C. or more to obtain a carrier including the composite oxide;
supporting a compound including the transition metal by the composite oxide to prepare a before-reducing process supporting material; and
performing a reducing process on the before-reducing process supporting material at 400° C. or more.

[claim17]
17. A manufacturing method for ammonia comprising bringing hydrogen, nitrogen, and a catalyst in contact with each other, the catalyst being the ammonia synthesis catalyst according to claim 14.

[claim18]
18. A metal-supported material in which a transition metal excluding Group-4 elements is supported by the composite oxide according to claim 9.

[claim19]
19. A manufacturing method for the metal-supported material according to claim 18, the manufacturing method comprising:
mixing an A precursor including A, an X precursor including X, and an M precursor including M to obtain a mixture;
calcinating the mixture at 600° C. or more to obtain a carrier including the composite oxide;
supporting a compound including the transition metal by the composite oxide to prepare a before-reducing process supporting material; and
performing a reducing process on the before-reducing process supporting material at 400° C. or more.
  • Inventor, and Inventor/Applicant
  • NAGAOKA KATSUTOSHI
  • OGURA YUTA
  • SATO KATSUTOSHI
  • JAPAN SCIENCE AND TECHNOLOGY AGENCY
IPC(International Patent Classification)
Reference ( R and D project ) CREST Creation of Innovative Core Technology for Manufacture and Use of Energy Carriers from Renewable Energy AREA
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