Electron or negative hydrogen ion adsorbing/releasing material, electron or negative hydrogen ion adsorbing/releasing composition, transition metal support, catalyst, and use thereof
阅读说明：本技术 电子或负氢离子吸收释放材料、电子或负氢离子吸收释放性组合物、过渡金属负载物及催化剂、以及与它们相关的用途 (Electron or negative hydrogen ion adsorbing/releasing material, electron or negative hydrogen ion adsorbing/releasing composition, transition metal support, catalyst, and use thereof ) 是由 小林洋治 阴山洋 山下大贵 T·布鲁 于 2019-03-13 设计创作，主要内容包括：本发明涉及使用了式Ln(HO)(式中,Ln表示镧系元素。)所示的镧系氧氢化物的电子或负氢离子吸收释放材料或者包含至少一种镧系氧氢化物的电子或负氢离子吸收释放性组合物、使过渡金属负载于它们而成的过渡金属负载物、以及包含上述过渡金属负载物的催化剂。本发明的电子或负氢离子吸收释放材料或者电子或负氢离子吸收释放性组合物具有比以往的含负氢化合物更高的电子或负氢离子吸收释放能力,通过负载过渡金属,从而能够作为具有优异的氨合成活性的催化剂等催化剂而有效地使用。(The present invention relates to an electron or negative hydrogen ion absorption/release material using a lanthanoid oxyhydroxide represented by the formula Ln (ho) (wherein Ln represents a lanthanoid element), or an electron or negative hydrogen ion absorption/release composition containing at least one lanthanoid oxyhydroxide, a transition metal support obtained by supporting a transition metal on the material, and a catalyst containing the transition metal support. The electron or negative hydrogen ion adsorbing and releasing material or the electron or negative hydrogen ion adsorbing and releasing composition of the present invention has a higher electron or negative hydrogen ion adsorbing and releasing ability than conventional negative hydrogen-containing compounds, and can be effectively used as a catalyst such as a catalyst having an excellent ammonia synthesis activity by supporting a transition metal.)
1. An electron or negative hydrogen ion absorption releasing material using a lanthanoid type oxyhydroxide represented by the following formula (1),
Ln(HO)···(1)
in formula (1), Ln represents a lanthanide.
2. The electron or negative hydrogen ion absorbing and releasing material as claimed in claim 1, wherein said lanthanoid series oxyhydroxide has lanthanoid series constituting crystal lattice, and negative hydrogen ion (H)-) With oxide ions (O)2-) A structure coexisting in the form of HO order type or HO solid solution type.
3. The electron or negative hydrogen ion absorbing and releasing material as claimed in claim 1, wherein said lanthanoid series oxyhydroxide has lanthanoid series constituting crystal lattice, and negative hydrogen ion (H)-) With oxide ions (O)2-) A structure in which HO is a solid solution type coexists.
4. An electron or negative hydrogen ion absorbing and releasing composition comprising at least one lanthanide oxy hydride.
5. The electronic or negative hydrogen ion absorbing-releasing composition according to claim 4, wherein the lanthanoid element contained in said lanthanoid oxyhydroxide is at least one selected from the group consisting of Gd, Sm, Pr, and Er.
6. The electron or negative hydrogen ion absorbing and releasing composition according to claim 4, wherein the lanthanoid element contained in the lanthanoid oxyhydroxide is at least one selected from the group consisting of Gd, Sm, and Er.
7. The electron or negative hydrogen ion absorbing and releasing composition according to claim 4, wherein said lanthanide series oxyhydroxide is represented by the following formula (2),
LnH(x)O((3-x)/2)(0＜x＜3)···(2)
in formula (2), Ln represents a lanthanoid.
8. The electron or negative hydrogen ion absorbing and releasing composition according to claim 7, wherein Ln in the formula (2) is at least one selected from the group consisting of Gd, Sm, Pr and Er.
9. The electron or negative hydrogen ion absorbing and releasing composition according to claim 7, wherein Ln in the formula (2) is at least one selected from the group consisting of Gd, Sm and Er.
10. The electron or negative hydrogen ion absorbing and releasing composition according to claim 4, wherein said lanthanide oxyhydroxide has a structure selected from the group consisting of ordered fluorite-type structure (P4/nmm), PbCl2Type structure (Pnma) and Fe2At least one crystalline structure of the group consisting of P-type structures (P62 m).
11. The electron or negative hydrogen ion absorbing and releasing composition according to claim 4, wherein said lanthanide oxy-hydride is a lanthanide oxy-hydride having a crystal structure obtained by heating a lanthanide oxide and a lanthanide hydride at a pressure of at least 2GPa or more in the absence of a gas.
12. A transition metal-supported material, wherein a transition metal is supported on the electron or negative hydrogen ion-adsorbing/releasing material or the electron or negative hydrogen ion-adsorbing/releasing composition according to any one of claims 1 to 11, and the transition metal does not include a lanthanoid.
13. The transition metal support of claim 12, wherein the transition metal is at least one selected from the group consisting of Ru, Fe, Co, Cr and Mn.
14. A catalyst comprising the transition metal support of claim 12 or 13.
15. The catalyst of claim 14, which has hydrogen reduction activity.
16. The catalyst of claim 14, which has ammonia synthesis activity.
17. Use of a lanthanide oxyhydroxide as an electron or negative hydrogen ion absorbing and releasing material, said lanthanide oxyhydroxide being obtained by a manufacturing process comprising the steps of:
a step (1) of mixing a lanthanide oxide with a metal hydride (excluding a lanthanide hydride);
a step (2) in which the obtained mixture is heated at a pressure of not less than normal pressure in the absence of a gas or in the presence of hydrogen or an inert gas; and a process for the preparation of a coating,
and (3) cleaning and removing the metal oxide and the unreacted metal hydride as by-products, if necessary, after the heating step.
18. Use of a lanthanide oxyhydroxide as an electron or negative hydrogen ion absorbing and releasing material, said lanthanide oxyhydroxide being obtained by a manufacturing process comprising the steps of:
a step (1) of mixing a lanthanide oxide with a lanthanide hydride; and a process for the preparation of a coating,
and (2) heating the obtained mixture in the absence of a gas under a pressure of at least 2GPa or more.
19. The use of the lanthanide oxyhydroxide according to claim 17 or 18 as an electron or negative hydrogen ion absorption/release material, wherein the heating is performed at a heating temperature of 400 to 900 ℃ for 12 to 72 hours.
20. Use of a transition metal support as a catalyst, the transition metal support being obtainable by a manufacturing method comprising the steps of:
a step (1) of mixing a lanthanide oxide with a metal hydride (excluding a lanthanide hydride);
a step (2) in which the obtained mixture is heated at a pressure of not less than normal pressure in the absence of a gas or in the presence of hydrogen or an inert gas;
a step (3) of removing, after the heating step, the metal oxide and the unreacted metal hydride as by-products by washing, if necessary; and a process for the preparation of a coating,
a step (4) of supporting a transition metal on the obtained lanthanide oxyhydroxide by an impregnation method,
wherein the transition metal does not include a lanthanide.
21. Use of a transition metal support as a catalyst, the transition metal support being obtainable by a manufacturing method comprising the steps of:
a step (1) of mixing a lanthanide oxide with a lanthanide hydride; and a process for the preparation of a coating,
a step (2) in which the obtained mixture is heated in the absence of a gas under a pressure of at least 2GPa or more; and a process for the preparation of a coating,
step (3) of supporting a transition metal on the obtained lanthanide oxyhydroxide by an impregnation method,
wherein the transition metal does not include a lanthanide.
22. The use of a transition metal support according to claim 20 or 21 as a catalyst, wherein the impregnation method comprises the steps of:
a step (A) in which the lanthanide oxyhydroxide is dispersed in a solution in which a transition metal compound is dissolved in a solvent, and the solvent is evaporated to obtain a supported material precursor; and a process for the preparation of a coating,
and (B) heating the obtained supported material precursor in a reducing atmosphere to obtain a transition metal supported material in which the transition metal in the transition metal compound is supported as nano metal particles on the oxyhydroxide.
23. The use of a transition metal support as a catalyst according to claim 22, wherein the impregnation method comprises heating the support precursor at a heating temperature of 100 to 700 ℃ for 1 to 5 hours.
24. A method for producing ammonia, comprising the steps of:
a step of supplying a gas containing hydrogen and nitrogen as a raw material in contact with the transition metal support or the catalyst according to any one of claims 12 to 16; and a process for the preparation of a coating,
and a step of synthesizing ammonia by heating the transition metal support or the catalyst in the gas atmosphere.
25. The method for producing ammonia according to claim 24, wherein the mixing molar ratio of nitrogen and hydrogen in the gas is about 1/10 to 1/1, the reaction temperature in the step of synthesizing ammonia is from room temperature to less than 500 ℃, and the reaction pressure in the step of synthesizing ammonia is from 10kPa to 20 MPa.
26. The method for producing ammonia according to claim 24 or 25, wherein the atmosphere of the gas in the step of synthesizing ammonia is an atmosphere having a water vapor partial pressure of 0.1kPa or less.
27. The method for producing ammonia according to any one of claims 24 to 26, comprising the steps of: a transition metal support or catalyst according to any one of claims 12 to 16 is subjected to a reduction treatment with hydrogen gas or a mixed gas of hydrogen and nitrogen before supplying a gas containing hydrogen and nitrogen as raw materials, thereby removing oxides adhering to the surface of the transition metal support or catalyst.
Technical Field
The present invention relates to an electron or negative hydrogen ion absorbing and releasing material, an electron or negative hydrogen ion absorbing and releasing composition, a transition metal support, a catalyst, and uses thereof, and more particularly, to an electron or negative hydrogen ion absorbing and releasing material using a lanthanoid-based oxyhydroxide, an electron or negative hydrogen ion absorbing and releasing composition containing a lanthanoid-based oxyhydroxide, a transition metal support in which a transition metal is supported on the electron or negative hydrogen ion absorbing and releasing material or the electron or negative hydrogen ion absorbing and releasing composition, a catalyst containing the transition metal support (further, a catalyst having a hydrogen reduction activity, a catalyst having an ammonia synthesis activity), a use of a lanthanoid-based oxyhydroxide as an electron or negative hydrogen ion absorbing and releasing material, and a use of the transition metal support as a catalyst. The term "hydrogen reduction activity" refers to the ability to increase the reactivity of a reduction reaction using hydrogen gas or a hydrogen compound as a reducing agent and to promote the reaction.
Background
One of the basic processes of the chemical industry for ammonia synthesis, using iron oxide as catalyst and potassium hydroxide as promoterThe Haber-Bosch (Haber-Bosch) process has become popular and has not changed much over about 100 years. In ammonia synthesis by the Haber-Bosch process, nitrogen and hydrogen are reacted over a catalyst at a high temperature and a high pressure of 300 to 500 ℃ and 20 to 40 MPa. Reaction for synthesizing ammonia by using gas containing hydrogen and nitrogen as raw materialThis shows that since this reaction is an exothermic reaction, the lower the temperature is, the better the equilibrium is shifted to the right, and since the number of molecules decreases with the reaction, the higher the pressure is, the better the equilibrium is shifted to the right.
However, nitrogen molecules have very strong triple bonds between nitrogen atoms and thus are extremely lack of reactivity, and the reaction of nitrogen with hydrogen is extremely slow. Therefore, it is very important to develop a catalyst capable of activating a nitrogen molecule by cleaving the triple bond. Haber et al uses iron ore as a catalyst, and the iron ore is a substance mainly composed of iron oxide and containing aluminum oxide and potassium oxide. In the haber-bosch method, iron oxide is loaded as a catalyst in a reaction apparatus, but metallic iron produced by reduction with hydrogen actually reacts. Alumina functions as a carrier without being reduced, prevents sintering of iron particles, and potassium oxide serves as a base to supply electrons to the iron particles, thereby improving catalytic performance. Due to the above-mentioned action, it is called a dual promoted iron catalyst. However, even when the iron catalyst is used, the reaction rate is not sufficient at a low temperature of 400 ℃.
In the industrial conventional technology, hydrogen is produced by reforming natural gas or the like, and this hydrogen is reacted with nitrogen in the atmosphere in the same facility under the above-described conditions to synthesize ammonia. As catalysts for ammonia synthesis, conventional Fe/Fe3O4In recent years, however, an Fe/C, Ru/C catalyst having activated carbon as a carrier has been used.
It is known that when metal catalyst particles for ammonia synthesis are formed by supporting Ru on a carrier and ammonia synthesis is performed using the catalyst particles, the reaction proceeds at low pressure, and attention is paid to the catalyst for ammonia synthesis as a new generation. However, with respect to Ru alone, the catalytic ability is very weak, beingIt is preferable to use a material having high electron donating property together with the ability to cleave a triple bond of a nitrogen molecule and convert it into an adsorbed nitrogen atom on the Ru metal catalyst particle, and a carrier made of a basic material, an alkali metal compound, an alkaline earth metal compound, or other promoter compound may be used instead of Fe3O4And active carbon.
On the other hand, with MTiO3Since titanium-containing oxides having a perovskite crystal structure or a layered perovskite crystal structure represented by (M is Ca, Ba, Mg, Sr, or Pb), titanium-containing oxides having a part of Ti substituted with at least one of Hf and Zr (collectively referred to as "titanium-containing perovskite oxides"), and the like have extremely high relative permittivity, they have been actively studied from the viewpoint of use as capacitor materials, dielectric films, and the like, as well as substrate materials of other perovskite transition metal oxides, nonlinear resistors, and the like.
Patent document 2 discloses: by containing negative hydrogen (H)-) When a catalyst is formed by using the titanium-containing perovskite-type oxyhydroxide as a carrier and supporting a metal exhibiting catalytic activity such as Ru or Fe thereon, hydrogen (H) is supported-) The activity of ammonia synthesis is dramatically improved without using unstable alkali metals, alkaline earth metals and their compounds as promotersIn the case of the promoter compound, the reaction is stable even for a long period of time, and the catalyst becomes an ammonia synthesis catalyst having a remarkably higher activity than a catalyst having the highest activity known in the past, and can realize highly efficient ammonia synthesis at a low pressure of less than 20 MPa. Further, patent document 2 discloses: when in ammonia or N2/H2Heating Ti-containing perovskite-type oxyhydroxide at a low temperature of 400 to 600 ℃ in a mixed gas flow, introducing nitride ions through an H/N exchange process of negative hydrogen (H) and nitrogen (N) to form BaTi (O, H, N)3。
Disclosure of Invention
As described above, the negative hydrogen-containing compound has various properties such as an electron-absorbing/releasing ability or a negative hydrogen ion-absorbing/releasing ability (hereinafter, also referred to as "electron-or negative hydrogen ion-absorbing/releasing ability" in some cases), and has ammonia-synthesizing activity due to its specific action.
The purpose of the present invention is to provide a material or the like which contains more negative hydrogen and has high electron or negative hydrogen ion absorption/release properties.
Means for solving the problems
The inventors of the present application have found that a lanthanide series oxyhydroxide has high electron or negative hydrogen ion absorption/release properties, and a catalyst or the like having excellent ammonia synthesis activity can be obtained by using the lanthanide series oxyhydroxide, and have completed the present invention.
Namely, the present invention is as follows.
[1] An electron or negative hydrogen ion absorption releasing material using a lanthanoid oxyhydroxide represented by the following formula (1).
[ chemical formula 1]
Ln(HO)...(1)
(in the formula (1), Ln represents a lanthanoid.)
[2]Such as [1]]The electron or negative hydrogen ion absorption and release material, wherein the lanthanide series oxyhydroxide hasWith lanthanides forming the lattice, and negative hydrogen ions (H)-) With oxide ions (O)2-) A structure coexisting in the form of HO order type or HO solid solution type.
[3]Such as [1]]The electron or negative hydrogen ion absorption/release material, wherein the lanthanide oxyhydroxide has a lanthanide constituting a crystal lattice, and a negative hydrogen ion (H-) and an oxide ion (O)2-) A structure in which HO is a solid solution type coexists.
[4] An electron or negative hydrogen ion absorbing and releasing composition comprising at least one lanthanide oxy hydride.
[5] The electron or negative hydrogen ion absorbing/releasing composition according to [4], wherein the lanthanoid element contained in the lanthanoid oxyhydroxide is at least one element selected from the group consisting of Gd, Sm, Pr and Er.
[6] The electron or negative hydrogen ion absorbing/releasing composition according to [4], wherein the lanthanoid element contained in the lanthanoid oxyhydroxide is at least one element selected from the group consisting of Gd, Sm, and Er.
[7] The electron or negative hydrogen ion absorbing/releasing composition according to [4], wherein the oxyhydroxide in the lanthanide series is represented by the following formula (2).
[ chemical formula 2]
LnH(x)O((3-x)/2)(O＜x＜3)...(2)
(in the formula (2), Ln represents a lanthanoid.)
[8] The electron-or negative hydrogen ion-absorbing and releasing composition according to [7], wherein Ln in the formula (2) is at least one selected from the group consisting of Gd, Sm, Pr and Er.
[9] The electron-or negative hydrogen ion-absorbing and releasing composition according to [7], wherein Ln in the formula (2) is at least one selected from the group consisting of Gd, Sm and Er.
[10]Such as [4]]The electron or negative hydrogen ion absorption/release composition, wherein the lanthanide oxyhydroxide has a structure selected from the group consisting of ordered fluorite structure (P4/nmm), PbCl2Type structure (Pnma) and Fe2At least one crystalline structure of the group consisting of P-type structures (P62 m).
[11] The electron or negative hydrogen ion absorbing and releasing composition according to [4], wherein the lanthanide oxyhydroxide is a lanthanide oxyhydroxide having a crystal structure obtained by heating a lanthanide oxide and a lanthanide hydride at a pressure of at least 2GPa or more in the absence of a gas.
(Note that "in the absence of gas", means a state in which a lanthanide oxide and a lanthanide hydride are charged into a reaction vessel so as not to generate a dead volume when the reaction vessel is charged, or a vacuum state, for example.)
[12] A transition metal-supported material comprising the electron or negative hydrogen ion-adsorbing/releasing material or the electron or negative hydrogen ion-adsorbing/releasing composition according to any one of [1] to [11] and a transition metal supported thereon. Wherein the transition metal does not include a lanthanide.
[13] The transition metal-supported material according to [12], wherein the transition metal is at least one selected from the group consisting of Ru, Fe, CO, Cr and Mn.
[14] A catalyst comprising the transition metal support of [12] or [13 ].
[15] The catalyst according to [14], which has hydrogen reduction activity.
(the term "hydrogen reduction activity" means the ability to promote a reduction reaction using hydrogen gas or a hydrogen compound as a reducing agent by improving the reactivity of the reaction)
[16] The catalyst according to [14], which has ammonia synthesis activity.
[17] Use of a lanthanide oxyhydroxide as an electron or negative hydrogen ion absorbing and releasing material, said lanthanide oxyhydroxide being obtained by a manufacturing process comprising the steps of:
a step (1) of mixing a lanthanide oxide with a metal hydride (excluding a lanthanide hydride);
a step (2) in which the obtained mixture is heated at a pressure of not less than normal pressure in the absence of a gas or in the presence of hydrogen or an inert gas; and a process for the preparation of a coating,
and (3) cleaning and removing the metal oxide and the unreacted metal hydride as by-products, if necessary, after the heating step.
(Note that "in the absence of gas" means a state where a lanthanide oxide and a metal hydride are filled into a reaction vessel so as not to generate a dead volume when the reaction vessel is filled, or a vacuum state, for example.)
[18] Use of a lanthanide oxyhydroxide as an electron or negative hydrogen ion absorbing and releasing material, said lanthanide oxyhydroxide being obtained by a manufacturing process comprising the steps of:
a step (1) of mixing a lanthanide oxide with a lanthanide hydride; and a process for the preparation of a coating,
and (2) heating the obtained mixture in the absence of a gas under a pressure of at least 2GPa or more.
(Note that "in the absence of gas", means a state in which a lanthanide oxide and a lanthanide hydride are charged into a reaction vessel so as not to generate a dead volume when the reaction vessel is charged, or a vacuum state, for example.)
[19] The use of the lanthanide oxyhydroxide according to [17] or [18] as an electron or negative hydrogen ion absorption/release material, wherein the heating temperature in the heating step is 400 to 900 ℃ and the heating time is 12 to 72 hours.
[20] Use of a transition metal support as a catalyst, the transition metal support being obtainable by a manufacturing method comprising the steps of:
a step (1) of mixing a lanthanide oxide with a metal hydride (excluding a lanthanide hydride);
a step (2) of heating the obtained mixture in the absence of a gas or in the presence of a hydrogen gas or an inert gas under a pressure of not less than normal pressure (preferably a pressure of less than 1 GPa);
a step (3) of removing, after the heating step, the metal oxide and the unreacted metal hydride as by-products by washing, if necessary; and a process for the preparation of a coating,
and (4) supporting the obtained lanthanide oxyhydroxide with a transition metal by an impregnation method.
Wherein the transition metal does not include a lanthanide.
(Note that "in the absence of gas" means a state where a lanthanide oxide and a metal hydride are filled into a reaction vessel so as not to generate a dead volume when the reaction vessel is filled, or a vacuum state, for example.)
[21] Use of a transition metal support as a catalyst, the transition metal support being obtainable by a manufacturing method comprising the steps of:
a step (1) of mixing a lanthanide oxide with a lanthanide hydride; and a process for the preparation of a coating,
a step (2) in which the obtained mixture is heated in the absence of a gas under a pressure of at least 2GPa or more; and a process for the preparation of a coating,
and (3) supporting the obtained lanthanide oxyhydroxide with a transition metal by an impregnation method.
Wherein the transition metal does not include a lanthanide.
(Note that "in the absence of gas", means a state in which a lanthanide oxide and a lanthanide hydride are charged into a reaction vessel so as not to generate a dead volume when the reaction vessel is charged, or a vacuum state, for example.)
[22] The use of a transition metal-supported material according to [20] or [21] as a catalyst, wherein the impregnation method comprises the steps of:
a step (a) in which the lanthanide oxyhydroxide is dispersed in a solution in which a transition metal compound is dissolved in a solvent, and the solvent is evaporated to obtain a supported material precursor; and a process for the preparation of a coating,
and (B) heating the obtained supported material precursor in a reducing atmosphere to obtain a transition metal supported material in which the transition metal in the transition metal compound is supported as nano metal particles on the oxyhydroxide.
[23] The use of a transition metal support as a catalyst according to [22], wherein in the impregnation method, the support precursor is heated at a heating temperature of 100 to 700 ℃ for 1 to 5 hours.
[24] A method for producing ammonia, comprising the steps of:
a step of supplying a gas containing hydrogen and nitrogen as raw materials in contact with the transition metal support or the catalyst according to any one of [12] to [16 ]; and a process for the preparation of a coating,
and a step of synthesizing ammonia by heating the transition metal support or the catalyst in the gas atmosphere.
[25] The method for producing ammonia as described in [24], wherein the mixing molar ratio of nitrogen and hydrogen in the gas is about 1/10 to 1/1, the reaction temperature in the step of synthesizing ammonia is from room temperature to less than 500 ℃, and the reaction pressure in the step of synthesizing ammonia is from 10kPa to 20 MPa.
[26] The method for producing ammonia as described in [24] or [25], wherein the atmosphere of the gas in the step of synthesizing ammonia is an atmosphere having a water vapor partial pressure of 0.1kPa or less.
[27] The method for producing ammonia according to any one of [24] to [26], comprising the steps of: the transition metal support or catalyst according to any one of [12] to [16] is subjected to a reduction treatment with hydrogen gas or a mixed gas of hydrogen and nitrogen before supplying a gas containing hydrogen and nitrogen as raw materials, thereby removing oxides adhering to the surface of the transition metal support or catalyst.
ADVANTAGEOUS EFFECTS OF INVENTION
The electron or negative hydrogen ion adsorbing and releasing material or the electron or negative hydrogen ion adsorbing and releasing composition of the present invention has high electron or negative hydrogen ion adsorbing and releasing properties, and a transition metal is supported thereon, whereby a catalyst such as a catalyst having excellent ammonia synthesis activity can be obtained.
Drawings
Fig. 1 is an X-ray diffraction pattern of the electron or negative hydrogen ion absorbing and releasing material obtained in examples 1 to 8 in this order from the top.
Fig. 2 is a diagram showing the arrangement of atoms in the crystal structure of a lanthanoid series oxyhydroxide used in the present invention. The left 2 figures in fig. 2 are diagrams showing the atomic arrangement of the lanthanoid atom (Ln), the hydrogen atom (H), and the oxygen atom (O) in the entire crystal structure of the lanthanoid oxyhydroxide used in the present invention. The right 2 figures in fig. 2 are diagrams showing the bonding form of the lanthanoid atom (Ln), the hydrogen atom (H), and the oxygen atom (O) contained in the entire crystal structure of the lanthanoid oxyhydroxide used in the present invention.
FIG. 3 is a graph showing a comparison of the catalytic activities of catalysts used in examples 11 and 12 and comparative example 2 for ammonia synthesis. The reaction conditions here were 400 ℃ and 5 MPa.
[ FIG. 4]]Fig. 4(a) is a diagram showing the crystal structure of lanthanide series oxyhydroxide contained in the electron or negative hydrogen ion absorption-release composition of the present invention, i.e., ordered fluorite type structure (P4/nmm). FIG. 4(b) is a view showing the crystal structure of a lanthanoid type oxyhydroxide contained in the electron or negative hydrogen ion absorption-releasing composition of the present invention, i.e., PbCl2Graph of type structure (Pnma). FIG. 4(c) is a view showing the crystal structure of lanthanide series oxyhydroxide contained in the electron or negative hydrogen ion absorption-releasing composition of the present invention, that is, Fe2Diagram of P-type structure (P62 m).
[ FIG. 5]]FIG. 5 shows the results of comparison of Ru/LaHO-hp of example 31, Ru/LaHO-ss of example 32 and Ru/Pr of comparative example 3 obtained at a reaction pressure of 0.1MPa2O3The catalytic activity of (a).
[ FIG. 6]]FIG. 6 shows the results of comparison of Ru/LaHO-hp of example 31, Ru/LaHO-ss of example 32 and Ru/Gd of comparative example 4 obtained at a reaction pressure of 1MPa2O3The catalytic activity of (a).
Detailed Description
< Electron-or negative hydrogen ion-adsorbing and releasing Material, and Electron-or negative hydrogen ion-adsorbing and releasing composition >
The electron or negative hydrogen ion absorbing/releasing material of the present invention is a negative hydrogen ion absorbing/releasing material formed of a lanthanoid oxyhydroxide represented by the following formula (1), or a negative hydrogen ion absorbing/releasing material containing the lanthanoid oxyhydroxide. The electron or negative hydrogen ion absorbing/releasing material may contain other components as long as the properties of the material are not lost.
[ chemical formula 3]
Ln(HO)...(1)
(in the formula (1), Ln represents a lanthanoid.)
The electron or negative hydrogen ion absorption-releasing composition of the present invention is a negative hydrogen ion absorption-releasing composition formed from at least one lanthanide series oxyhydroxide, or a negative hydrogen ion absorption-releasing composition containing the lanthanide series oxyhydroxide. The electron or negative hydrogen ion absorbable and releasable composition may contain other components as long as the properties of the composition are not lost.
The lanthanide oxyhydroxide can have lanthanide constituting lattice and negative hydrogen ion (H)-) With oxide ions (O)2-) A structure coexisting in the form of HO order type or HO solid solution type.
Here, the lanthanoid (or lanthanoid) is an element having an atomic number of 57 to 71. Specifically, lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu).
The lanthanoid (or lanthanoid) which is one constituent of the lanthanoid oxyhydroxide used in the electron or negative hydrogen ion absorption/emission material of the present invention or the lanthanoid oxyhydroxide contained in the electron or negative hydrogen ion absorption/emission composition of the present invention preferably includes at least one selected from the group consisting of Gd, Sm, Pr, and Er. More preferably, at least one selected from the group consisting of Gd, Sm, and Er.
Formula (1) represents a lanthanide series oxyhydroxide. The lanthanide hydrides being formed by hydride ions (H)-) A compound obtained by substituting a part of oxide ions contained in an oxide of a lanthanoid.
Specifically, the lanthanide oxyhydroxide represented by formula (1) is La (HO), Ce (HO), Pr (HO), Nd (HO), Pm (HO), Sm (HO), Eu (HO), Gd (HO), Tb (HO), Dy (HO), Ho (HO), Er (HO), Tm (HO), Yb (HO) and Lu (HO). Among these, regarding La (HO), in documents (I) J.F.Brice, A.Moreau, ANN.Chim.Fr., 1982, 7pp.623-634, and documents (II) B.Malaman, J.F.Brice, J.solid State chem.1984, 53, 44-54, the ordered fluorite-type structure thereof (P4/nmm) is disclosed, and regarding Nd (HO), in documents (III) M.Wideroe, J.solid State chem.2011, 184, 1890-1894, the ordered fluorite-type structure thereof (P4/nmm) is disclosed.
Further, document (I) discloses a summary of crystal structures of ce (ho) and pr (ho).
Regarding the crystal structures of La (HO) and Nd (HO), the ordered fluorite structure (P4/nmm) is discussed in the above-mentioned documents (I) to (III).
The lanthanide oxyhydroxide contained in the electron or negative hydrogen ion absorption-releasing composition of the present invention has a crystal structure selected from the group consisting of ordered fluorite structure (P4/nmm), PbCl2Type structure (Pnma) and Fe2At least one of the group consisting of P-type structures (P62 m).
These crystal structures are obtained by: in the method of producing the above lanthanide oxy-hydride, the lanthanide oxide and the lanthanide hydride are heated in the absence of a gas at a pressure of at least 2GPa or more.
The term "in the absence of a gas" means a state in which a lanthanide oxide and a lanthanide hydride are filled into a reaction vessel so as not to generate a dead volume when the reaction vessel is filled with the lanthanide oxide and the lanthanide hydride, or a vacuum state.
The heating temperature in the heating step is, for example, 400 to 900 ℃. The heating time is, for example, 12 to 72 hours.
Specifically, for example, when the lanthanoid oxyhydroxide is lanthanoid oxyhydroxide, a powder of lanthanum oxide and a powder of lanthanum hydride are mixed, and a powder sample of the obtained mixture is filled into a reaction vessel so as not to generate a dead volume (that is, in the absence of a gas), and then the reaction vessel is placed in an anvil press (anvil press) device with a heating function, and mechanically pressurized (under a pressure of at least 2GPa or more) and heated.
Here, when the pressure is normal pressure, the crystal structure of the obtained lanthanide series oxyhydroxide becomes an ordered fluorite type structure (P4/nmm) as shown in FIG. 4(a), and when the pressure is 3GPa, the crystal structure of the obtained lanthanide series oxyhydroxide is as shown in FIG. 4(b)The bulk structure becomes PbCl2When the form (Pnma) is a type structure and the pressure is 5GPa, the crystal structure of the obtained lanthanide oxyhydroxide becomes Fe as shown in FIG. 4(c)2P-type structure (P62 m).
The crystal structure of the obtained lanthanide oxyhydroxide corresponds to various conditions such as the kind of lanthanide contained in the lanthanide oxyhydroxide, pressure, and heating time.
The crystal structure of the lanthanide series oxyhydroxide is also described in detail in the examples described later.
The oxygen hydride of lanthanoid contained in the electron or negative hydrogen ion absorption-release composition of the present invention may be a compound represented by the following formula (2).
[ chemical formula 4]
LnH(x)O((3-x)/2)(O＜x＜3)...(2)
(in the formula (2), Ln represents a lanthanoid.)
Here, the lanthanoid element is the same as described above.
Specifically, the lanthanide series oxyhydroxide represented by formula (2) is La1-y·(H1-xOx/2)y、Ce1-y·(H1-xOx/2)y、Pr1-y·(H1-xOx/2)y、Nd1-y·(H1-xOx/2)y、Pm1-y·(H1-xOx/2)y、Sm1-y·(H1-xOx/2)y、Eu1-y·(H1-xOx/2)y、Gd1-y·(H1-xOx/2)y、Tb1-y·(H1-xOx/2)y、Dy1-y·(H1-xOx/2)y、Ho1-y·(H1-xOx/2)y、Er1-y·(H1- xOx/2)y、Tm1-y·(H1-xOx/2)y、Yb1-y·(H1-xOx/2)yAnd Lu1-y·(H1-xOx/2)y。
The composition ratio of each element in the above-mentioned lanthanide series oxyhydroxide can be arbitrarily determined. That is, the value of x in the formula (2) may be arbitrarily determined in the range of 0< x < 3.
By changing the composition ratio of each element, a material having different electron or negative hydrogen ion absorption/release capabilities depending on each of the lanthanoid elements contained in the lanthanoid oxyhydroxide can be obtained. The lanthanide series oxyhydroxide may be one kind of lanthanide series oxyhydroxide, or two or more kinds of lanthanide series oxyhydroxides.
The composition ratio of each element and the type of the lanthanide element contained in the above-described lanthanide oxyhydroxide can be appropriately selected according to the desired performance. The lanthanide hydrides described above having any composition ratio can be synthesized by appropriately adjusting the atomic ratio of hydrogen to oxygen during synthesis.
The electron or negative hydrogen ion absorption/release material or the electron or negative hydrogen ion absorption/release composition of the present invention is a material using a lanthanoid series oxyhydroxide or a composition containing at least one lanthanoid series oxyhydroxide, and has a high electron or negative hydrogen ion absorption/release capacity. The above-mentioned electron or negative hydrogen ion adsorbing and releasing material or electron or negative hydrogen ion adsorbing and releasing composition has such characteristics, and therefore, is expected to be used in various applications. For example, the electron or negative hydrogen ion adsorbing and releasing material or the electron or negative hydrogen ion adsorbing and releasing composition of the present invention can be effectively used as a catalyst such as a catalyst having an excellent ammonia synthesizing activity by supporting a transition metal thereon.
The shape, size, and the like of the electron or negative hydrogen ion adsorbing and releasing material or the electron or negative hydrogen ion adsorbing and releasing composition are not particularly limited, and may be determined as appropriate according to the application and the like in which they are used.
The lanthanoid oxyhydroxide used in the electron or negative hydrogen ion adsorbing and releasing material of the present invention or the lanthanoid oxyhydroxide contained in the electron or negative hydrogen ion adsorbing and releasing composition may be produced by a method including the following steps ((1) high pressure method and (2) normal pressure method), for example.
< 1) high pressure method >
Manufacturing method comprising the following steps
A step (1) of mixing a lanthanide oxide with a lanthanide hydride; and a process for the preparation of a coating,
and (2) heating the obtained mixture in the absence of a gas under a pressure of at least 2GPa or more.
The term "in the absence of a gas" means a state in which a lanthanide oxide and a lanthanide hydride are filled into a reaction vessel so as not to generate a dead volume when the reaction vessel is filled with the lanthanide oxide and the lanthanide hydride, or a vacuum state.
The heating temperature in the heating step is, for example, 400 to 900 ℃. The heating time is, for example, 12 to 72 hours. Further, examples of the pressure include 2GPa or more and less than 6GPa, and preferably 2GPa or more and less than 4 GPa.
Specifically, for example, in the case of a lanthanoid oxyhydroxide used in the electron or negative hydrogen ion absorption-release material of the present invention or a lanthanoid oxyhydroxide contained in the electron or negative hydrogen ion absorption-release composition, it can be produced by: the lanthanide oxide is mixed with the lanthanide hydride and heated at a high pressure, for example, 3GPa, 5GPa, etc. The heating temperature is, for example, about 900 ℃. The heating time is, for example, 12 to 72 hours.
In such a method, for example, after a powder sample of the mixture obtained by mixing a powder of lanthanum oxide and a powder of lanthanum hydride is filled into a reaction vessel so as not to generate a dead volume (that is, in the absence of a gas), the reaction vessel is set in an anvil device with a heating function, and mechanical pressurization (under a pressure of at least 2GPa or more) and heating are performed. Detailed manufacturing methods are shown in the examples.
The chemical reaction is represented by the following formula (3).
[ chemical formula 5]
La2O3+LaH2.5→2LaHO (3)
(in the formula (3), Ln represents a lanthanoid.)
< 2) Normal pressure method >
Manufacturing method comprising the following steps
A step (1) of mixing a lanthanide oxide with a metal hydride (excluding a lanthanide hydride);
a step (2) of heating the obtained mixture at a pressure of not less than normal pressure (preferably at a pressure of less than 1 GPa) in the absence of a gas or in the presence of a hydrogen gas or an inert gas; and a process for the preparation of a coating,
and (3) cleaning and removing the metal oxide and the unreacted metal hydride as by-products, if necessary, after the heating step.
The term "in the absence of a gas" means a state in which a lanthanide oxide and a metal hydride are filled into a reaction vessel so as not to generate a dead volume when the reaction vessel is filled with the lanthanide oxide and the metal hydride, or a vacuum state.
The heating temperature in the step of heating is, although dependent on the lanthanide oxyhydroxide to be produced, for example, 200 to 900 ℃, preferably 300 to 900 ℃, more preferably 400 to 900 ℃, and particularly preferably 600 to 700 ℃. The heating time depends on the lanthanide oxyhydroxide to be produced, but is, for example, 2 to 72 hours, preferably 12 to 72 hours, or 2 to 36 hours, more preferably 12 to 36 hours.
Specifically, for example, the lanthanoid oxyhydroxide used in the electron or negative hydrogen ion absorption-release material of the present invention or the lanthanoid oxyhydroxide contained in the electron or negative hydrogen ion absorption-release composition can be produced by: the lanthanide oxide is mixed with a metal hydride such as calcium hydride, sodium hydride, or lithium hydride, and heated under normal pressure in the absence of a gas (for example, in a state where the lanthanide oxide and the metal hydride are filled into a reaction vessel so as not to generate a dead volume when the reaction vessel is filled with the lanthanide oxide or the metal hydride, or in a vacuum) or in a hydrogen gas. The amount of the metal hydride such as calcium hydride to be mixed is preferably 300 to 1000 mol%, more preferably 300 to 400 mol% based on the lanthanide oxide. The heating temperature is, for example, 400 to 900 ℃, preferably 600 to 700 ℃. The heating time is 12 to 72 hours, preferably 12 to 36 hours. Detailed manufacturing methods are shown in the examples.
When the metal hydride is calcium hydride, the chemical reaction is represented by the following formula (4).
[ chemical formula 6]
Ln2O3+2CaH3→2LnHO+2CaO (4)
(in the formula (4), Ln represents a lanthanoid.)
< transition Metal Supports >
The transition metal support of the present invention is a transition metal support in which the electron or negative hydrogen ion-absorbing/releasing material or the electron or negative hydrogen ion-absorbing/releasing composition of the present invention is supported by a transition metal. Wherein the transition metal does not include a lanthanide.
In the transition metal-supported material, the transition metal may be at least one selected from the group consisting of Ru, Fe, Co, Cr and Mn.
Hereinafter, typical examples of the transition metal-supported substance of the present invention will be described.
(1)La(HO)
Ru/La (HO), Fe/La (HO), Co/La (HO), Cr/La (HO) and Mn/La (HO)
(2)Ce(HO)
Ru/Ce (HO), Fe/Ce (HO), Co/Ce (HO), Cr/Ce (HO), and Mn/Ce (HO)
(3)Pr(HO)
Ru/Pr (HO), Fe/Pr (HO), Co/Pr (HO), Cr/Pr (HO), and Mn/Pr (HO)
(4)Nd(HO)
Ru/Nd (HO), Fe/Nd (HO), Co/Nd (HO), Cr/Nd (HO), and Mn/Nd (HO)
(5)Pm(HO)
Ru/Pm (HO), Fe/Pm (HO), Co/Pm (HO), Cr/Pm (HO), and Mn/Pm (HO)
(6)Sm(HO)
Ru/Sm (HO), Fe/Sm (HO), Co/Sm (HO), Cr/Sm (HO) and Mn/Sm (HO)
(7)Eu(HO)
Ru/Eu (HO), Fe/Eu (HO), Co/Eu (HO), Cr/Eu (HO), and Mn/Eu (HO)
(8)Gd(HO)
Ru/Gd (HO), Fe/Gd (HO), Co/Gd (HO), Cr/Gd (HO), and Mn/Gd (HO)
(9)Tb(HO)
Ru/Tb (HO), Fe/Tb (HO), Co/Tb (HO), Cr/Tb (HO) and Mn/Tb (HO)
(10)Dy(HO)
Ru/Dy (HO), Fe/Dy (HO), Co/Dy (HO), Cr/Dy (HO), and Mn/Dy (HO)
(11)Ho(HO)
Ru/Ho (HO), Fe/Ho (HO), Co/Ho (HO), Cr/Ho (HO), and Mn/Ho (HO)
(12)Er(HO)
Ru/Er (HO), Fe/Er (HO), Co/Er (HO), Cr/Er (HO), and Mn/Er (HO)
(13)Tm(HO)
Ru/Tm (HO), Fe/Tm (HO), Co/Tm (HO), Cr/Tm (HO), and Mn/Tm (HO)
(14)Yb(HO)
Ru/Yb (HO), Fe/Yb (HO), Co/Yb (HO), Cr/Yb (HO), and Mn/Yb (HO)
(15)Lu(HO)
Ru/Lu (HO), Fe/Lu (HO), Co/Lu (HO), Cr/Lu (HO), and Mn/Lu (HO)
< catalyst containing transition Metal Supports >
The catalyst of the present invention is a catalyst comprising the transition metal support of the present invention. The catalyst has high absorption and release capacity of electrons or negative hydrogen ions. Because of such characteristics, the catalyst is expected to be used in various applications such as a catalyst having hydrogen reduction activity and a catalyst having ammonia synthesis activity. In particular, the catalyst can be effectively used as a catalyst for ammonia synthesis. The term "hydrogen reduction activity" refers to the ability to increase the reactivity of a reduction reaction using hydrogen gas or a hydrogen compound as a reducing agent and to promote the reaction.
The reason why the transition metal support functions as a catalyst for ammonia synthesis is considered to be: catalyst carrier (electron or negative hydrogen ion)A sub-absorbing and releasing material, an electron or negative hydrogen ion absorbing and releasing composition) to exert a specific action on the nitrogen molecule and the hydrogen molecule as the raw materials. That is, it is presumed that the lanthanide oxyhydroxide contained in the catalyst support dissociates nitrogen molecules and hydrogen molecules from the transition metal as the active species at about 300 to 450 ℃, and that the dissociation of N — N bonds is promoted by the electron supply from the hydride ion as well as the preferential overflow of the excessive hydrogen dissociation products to the support. From this, it is considered that the poisoning due to the accumulation of the transition metal particles as the active species by hydrogen is suppressed. This is considered to be a catalyst containing negative hydrogen (H) under the conditions of synthesis from ammonia, which is completely different from the conventional catalyst carrier-) The lanthanide hydrides of (a) have a function due to the unknown nature.
As will be understood from the examples described later, preferable examples of the ammonia synthesis activity of the transition metal supported substance of the present invention include:
(1) 10 mmol/g at a reaction pressure of 5MPa in the mixed gas of nitrogen and hydrogen in the ammonia synthesis reaction-1·H-1The above ammonia synthesis activity;
(2) 5 mmol/g at a reaction pressure of 1MPa in the mixed gas of nitrogen and hydrogen in the ammonia synthesis reaction-1·H-1The above ammonia synthesis activity;
(3) 1 mmol/g at a reaction pressure of 0.1MPa in the mixed gas of nitrogen and hydrogen in the ammonia synthesis reaction-1·H-1The above ammonia synthesis activity; and so on.
The mode of using the transition metal-supported product of the present invention as a catalyst for ammonia synthesis will be described below.
The lanthanoid (or lanthanoid) which is one constituent of the lanthanoid oxyhydroxide contained in the catalyst carrier (the electron or negative hydrogen ion adsorbing and releasing material, the electron or negative hydrogen ion adsorbing and releasing composition) is preferably at least one selected from the group consisting of Gd, Sm, Pr, and Er from the viewpoint of obtaining a catalyst having high ammonia synthesis activity. More preferably, at least one selected from the group consisting of Gd, Sm, and Er. More preferably, at least one selected from the group consisting of Gd and Sm, and particularly preferably, Gd is used.
Use of N as a lanthanide oxyhydroxide contained in a catalyst support (electron or negative hydrogen ion absorbing and releasing material, electron or negative hydrogen ion absorbing and releasing composition)2The specific surface area measured by the adsorption BET method is preferably 1m from the viewpoint of obtaining high catalytic activity2More than g. More preferably 5m2More than g. The upper limit of the specific surface area is not particularly limited, and may be 15m in actuality2And about/g.
The average particle diameter of the lanthanoid-based oxyhydroxide contained in the catalyst carrier (electron or negative hydrogen ion adsorbing and releasing material, electron or negative hydrogen ion adsorbing and releasing composition) is preferably 2 μm or less from the viewpoint of obtaining high catalytic activity. More preferably 500nm or less. The average particle diameter is based on the use of N2The surface area measured by the adsorption/BET method is a value obtained assuming that the particles are spherical.
The transition metal supported by the lanthanoid oxyhydroxide contained in the catalyst carrier (electron or negative hydrogen ion adsorbing and releasing material, electron or negative hydrogen ion adsorbing and releasing composition) is preferably Ru, Fe, Co, Mn from the viewpoint of obtaining a highly active catalyst. Further preferably, Ru is used.
The transition metal supported by the lanthanoid oxyhydroxide contained in the catalyst carrier (electron or negative hydrogen ion adsorbing and releasing material, electron or negative hydrogen ion adsorbing and releasing composition) is preferably in a particulate form.
The average particle diameter is preferably 1 to 50nm, for example. More preferably 2 to 5 nm. The average particle diameter is based on the use of N2The surface area measured by the adsorption/BET method is a value obtained assuming that the particles are spherical.
The amount of the transition metal supported by the lanthanoid oxyhydroxide contained in the catalyst carrier (the electron or negative hydrogen ion adsorbing and releasing material, the electron or negative hydrogen ion adsorbing and releasing composition) is preferably 0.1 to 20% by mass, for example, with respect to the lanthanoid oxyhydroxide. More preferably 1 to 10 mass%. More preferably, it is 2 to 6% by mass. Here, when the amount of the transition metal supported is less than 0.1 mass%, the catalytic activity tends to be low. On the other hand, when the amount of the transition metal supported exceeds 20 mass%, ammonia synthesis activity corresponding to the amount of the transition metal supported tends to be unobservable.
The shape of the catalyst for ammonia synthesis is not particularly limited, and may be a powder, a molded article obtained by molding a powder or the like into a fixed shape such as a cylinder, a ring, or a sphere by an extrusion molding method or a tablet molding method, an amorphous body obtained by molding into a fixed shape and then pulverizing, or the like.
The transition metal supported material of the present invention may be produced by a method including, for example, the following steps.
< first method (corresponding to the above-mentioned "(1) high pressure method)") > (
Manufacturing method comprising the following steps
A step (1) of mixing a lanthanide oxide with a lanthanide hydride; and a process for the preparation of a coating,
a step (2) in which the obtained mixture is heated in the absence of a gas under a pressure of at least 2GPa or more; and a process for the preparation of a coating,
(3) a step of supporting the obtained lanthanide oxyhydroxide with a transition metal by an impregnation method,
wherein the transition metal does not include a lanthanide.
The term "in the absence of a gas" means a state in which a lanthanide oxide and a lanthanide hydride are filled into a reaction vessel so as not to generate a dead volume when the reaction vessel is filled with the lanthanide oxide and the lanthanide hydride, or a vacuum state.
The heating temperature in the heating step is, for example, 400 to 900 ℃. The heating time is, for example, 12 to 72 hours.
< second method (corresponding to the above-mentioned "(2) atmospheric pressure method")
Manufacturing method comprising the following steps
A step (1) of mixing a lanthanide oxide with a metal hydride (excluding a lanthanide hydride);
a step (2) in which the obtained mixture is heated at a pressure of not less than normal pressure in the absence of a gas or in the presence of a hydrogen gas or an inert gas;
a step (3) of removing, after the heating step, the metal oxide and the unreacted metal hydride as by-products by washing, if necessary; and a process for the preparation of a coating,
(4) a step of supporting the obtained lanthanide oxyhydroxide with a transition metal by an impregnation method,
wherein the transition metal does not include a lanthanide.
The term "in the absence of a gas" means a state in which a lanthanide oxide and a metal hydride are filled into a reaction vessel so as not to generate a dead volume when the reaction vessel is filled with the lanthanide oxide and the metal hydride, or a vacuum state.
The heating temperature in the step of heating (i.e., the reaction temperature for thermally decomposing the transition metal compound) depends on the lanthanide oxyhydroxide, but is, for example, 200 to 900 ℃, preferably 300 to 900 ℃, more preferably 400 to 900 ℃, and particularly preferably 600 to 700 ℃. The heating time depends on the lanthanide oxyhydroxide, but is, for example, 2 to 72 hours, preferably 12 to 72 hours or 2 to 36 hours, more preferably 12 to 36 hours.
The impregnation method includes, for example, a method including the following steps.
A step (a) in which the lanthanide oxyhydroxide is dispersed in a solution obtained by dissolving a transition metal compound in a solvent (for example, an organic solvent such as hexane, acetone, or tetrahydrofuran), and the solvent is evaporated to obtain a supported material precursor; and a process for the preparation of a coating,
and (B) heating the obtained supported material precursor in a reducing atmosphere to obtain a transition metal supported material in which the transition metal in the transition metal compound is supported as nano metal particles on the oxyhydroxide.
In the impregnation method, the heating temperature (i.e., the reaction temperature for reducing the transition metal compound) when the support precursor is heated is, for example, 100 to 700 ℃, preferably 300 to 600 ℃. The heating time is, for example, 1 to 5 hours.
Examples of the transition metal compound include chlorides, carbonyl compounds, and complexes. Among them, a carbonyl compound and a complex are preferable from the viewpoint of maintaining the above-described characteristics of the lanthanide oxyhydroxide contained in the catalyst carrier (electron or negative hydrogen ion adsorbing and releasing material, electron or negative hydrogen ion adsorbing and releasing composition) and of being easily decomposed. For example, when the transition metal to be supported is Ru, examples of the transition metal compound include ruthenium chloride, ruthenium carbonyl, ruthenium acetylacetonate, potassium ruthenate, ruthenium oxide, and ruthenium nitrate.
An example of the method for producing a transition metal supported object of the present invention is shown below.
The lanthanoid oxyhydroxide contained in the catalyst carrier (the electron or negative hydrogen ion adsorbing and releasing material, the electron or negative hydrogen ion adsorbing and releasing composition) may be produced by a method shown as a method for producing the lanthanoid oxyhydroxide used in the electron or negative hydrogen ion adsorbing and releasing material or the lanthanoid oxyhydroxide contained in the electron or negative hydrogen ion adsorbing and releasing composition. The produced lanthanide oxyhydroxide can be pulverized by a ball mill or the like as appropriate to have a specific surface area and an average particle diameter in the above-mentioned ranges.
The transition metal may be produced by the method described as the method for producing a transition metal support of the present invention, in order to support the lanthanide oxyhydroxide contained in the catalyst support (electron or negative hydrogen ion-adsorbing/releasing material, electron or negative hydrogen ion-adsorbing/releasing composition). The produced transition metal supported material can be appropriately pulverized by a ball mill or the like to have a desired specific surface area and average particle diameter.
In the present invention, a transition metal support as a catalyst (particularly an ammonia synthesis catalyst) may be produced by supporting a transition metal as an active species on a catalyst support (an electron or negative hydrogen ion adsorbing and releasing material, an electron or negative hydrogen ion adsorbing and releasing composition).
The catalyst has a wide range of applications, and is essential for the economical production of chemicals using a catalytic reaction in petrochemical, coal chemical, C1 chemical for producing various chemicals from methane, ammonia synthesis, and the like, and a large number of catalytic processes (for example, ziegler-natta catalysts for polymerizing olefins, catalysts for making nitrogen oxides and sulfur oxides harmless) have been developed according to social needs.
Catalysts can be broadly classified into heterogeneous catalysts and homogeneous catalysts. In the former case, the reaction proceeds on the catalyst surface, and therefore the interfacial chemistry becomes important. In the latter case, the reaction is mostly carried out in solution, so knowledge of the solution chemistry is required. In catalytic chemistry, analysis of reactions using various kinetic or spectroscopic methods is often performed, and therefore extensive knowledge of physicochemical is generally required.
The heterogeneous catalyst is typically produced by granulating a powdered or granulated transition metal-supported material, extruding or granulating the granulated material, and then subjecting the granulated material to calcination and/or reduction in some cases. Alternatively, the catalyst support formed by granulating or extruding the material may be impregnated with a solution of the active species and dried before the calcination and reduction stages. For application to a catalytic reaction for the purpose of diversification of the geometric structure and physical properties of the catalyst to be provided, a method of granulating, extruding, or pelletizing effective for the catalytic reaction can be appropriately selected (see also the following description).
Examples of the method for producing such a heterogeneous catalyst include an impregnation method and a sol-gel method.
The impregnation method is the most convenient and commonly used method for producing a catalyst. In the production of a catalyst by the impregnation method, there is an advantage that the supported active species are substantially exposed to the surface, but on the other hand, it is necessary to prepare in advance a catalyst carrier to be used as a carrier (or purchase). In addition, depending on the characteristics of the powder or granule used as the catalyst carrier, the supported state may be affected, and particularly when the powder or granule having a small specific surface area is used as the carrier, since a large amount of active species cannot be supported, the catalytic activity per unit amount of catalyst may be limited, and therefore, it is preferable to confirm in advance whether or not the amount of catalyst is an appropriate amount of catalyst each time.
In the present invention, in the production of a catalyst for ammonia synthesis in which ammonia is synthesized by reacting hydrogen and nitrogen using a gas containing hydrogen and nitrogen as raw materials, for example, a catalyst carrier used as a carrier is prepared in advance (catalyst carrier producing step). If necessary, the catalyst carrier may be treated with NH under a nitrogen atmosphere4The by-product and unreacted raw material are washed with a solvent such as a Cl saturated methanol solution, and the remaining solid component is recovered by suction filtration and dried under a nitrogen atmosphere, thereby producing a catalyst carrier with higher purity.
After such a catalyst carrier producing step, the catalyst carrier prepared in advance as described above may be loaded with an active species (active species loading step). The active species supporting step may be carried out in a solvent in which the transition metal-containing compound is dissolved in advance. The solution obtained by dissolving the transition metal-containing compound and the catalyst support obtained in the previous step are mixed with stirring.
Examples of the stirring device include known stirring devices such as a rotary blade stirrer, a high-speed rotary shear stirrer (such as a homogenizer), a pendulum-type linear motion stirrer, an oscillator for oscillating the entire container, and a vibration stirrer using ultrasonic waves or the like. The rotation speed of the stirring blade or the rotary blade in the rotary stirring device may be appropriately adjusted in consideration of the shape of the vessel, the stirring blade, the baffle, and the like, the liquid amount, and the like, to the extent that no trouble such as scattering of the liquid occurs. The stirring may be carried out continuously or intermittently, preferably continuously.
The stirring time is, for example, 30 minutes or more. Preferably, it is 30 minutes to 24 hours. The temperature during stirring may be, for example, 20 to 80 ℃. Preferably, the temperature is 40 to 70 ℃.
The mixing ratio of the transition metal-containing compound in the mixture is, for example, 0.1 to 20% by volume based on the catalyst carrier. Preferably, it is 2 vol%. Subsequently, the solvent was removed under reduced pressure. The temperature for removing the solvent is, for example, 5 to 120 ℃. Preferably, normal temperature is used. The pressure is, for example, 0.1 to 0.1 MPa. Preferably 4 kPa.
By the above stirring, the transition metal-containing compound forms, for example, a complex with the catalyst support, and is substantially uniformly and finely dispersed. Then, the solvent is evaporated and removed (usually, vacuum distillation, heating, centrifugal separation), thereby recovering the transition metal load having high activity.
The requirements for the solvent used in the active species supporting step include, for example: the volatile is easy; the structure is simple; and the solubility of the transition metal-containing compound (specifically, for example, a compound containing a transition metal in the form of an oxide, a nitride, an oxynitride, a chloride, a carbonyl compound, or a transition metal complex) is high; and so on. Examples of the solvent which volatilizes at a low temperature, has a simple structure, and has high solubility in the transition metal-containing compound in the main solvent at room temperature include tetrahydrofuran, acetone, acetonitrile, hexane, isopropyl alcohol, ethanol, methanol, and the like. If the solvent is substantially soluble, the solvent can be supported, but if the solubility is low, the solvent becomes a dilute solution, which is costly in terms of process. In the present invention, the transition metal-containing compound may be dissolved in the solvent in advance, and then may be added to the catalyst support obtained in the previous step.
In addition, if necessary, in order to substantially simultaneously carry out oxidation of the catalyst carrier and metallization of the active species supported thereon, heat treatment (at a temperature of, for example, 100 to 700 ℃) may be carried out in vacuum, under reduced pressure, under a reducing gas atmosphere such as hydrogen, carbon monoxide, or ammonia, or under an inert gas atmosphere such as nitrogen, argon, or helium. Preferably, the transition metal-supported material in which the transition metal is supported as the nano-metal particles on the catalyst support can be obtained by heating in a reducing atmosphere to reduce the transition metal compound contained in the transition metal-containing compound, or by heating in a vacuum to thermally decompose the transition metal compound contained in the transition metal-containing compound.
The heat treatment may be performed using a firing furnace such as a rotary furnace, a fixed furnace, a tubular furnace, a tunnel furnace, a muffle furnace, or a fluidized firing furnace. From the viewpoint of not breaking the molded article, a fixing furnace is preferably used. By performing such a heat treatment, the active species can be supported on the catalyst carrier in a more uniformly and finely dispersed state (for example, in a bulk density of 0.6 to 0.85 kg/L). Therefore, it is possible to effectively suppress the embedding of active species in the catalyst carrier and ensure active species exposed on the surface of the catalyst, and therefore, a transition metal support having higher activity can be obtained as a more excellent catalyst. When the reaction is carried out under a hydrogen atmosphere, the pressure of hydrogen is, for example, 0.01 to 0.5 MPa. Preferably 0.1 MPa. By such a heat treatment, a chemically stable, thermally stable catalyst having a high catalytic activity can be obtained.
When the heat treatment step is performed in vacuum or under reduced pressure, substances generated by condensation or the like and solvents are likely to be vaporized during the catalyst firing in the heat treatment step, and thus crystal growth associated with the reduction of the catalyst carrier can be suppressed. In the heat treatment step, it is preferably performed under reduced pressure, and more preferably under vacuum in order to further exhibit the above-described effects.
The crystal structure of the transition metal support is influenced by the product of the firing temperature and the firing time, and therefore the firing temperature and the firing time are preferably set appropriately. The firing temperature is, for example, 100 to 700 ℃. Preferably 300 to 600 ℃. The firing time is, for example, 3 to 48 hours. Preferably 3 to 24 hours. More preferably 1 to 5 hours.
When a transition metal-supported material is molded, a small amount of a binder can be added to obtain a molded article having excellent moldability and strength. The molding may be performed before the heat treatment step, or may be performed after the heat treatment step.
Such a transition metal supported material is shaped by tablet forming, extrusion forming, rolling granulation, spray drying and the like and is put to practical use. The shape of the molded article is not particularly limited, and examples thereof include spherical, cylindrical, annular (cylindrical), and star-shaped shapes. Among them, the shaped catalyst is preferably cylindrical or annular with high compressive strength.
In order to obtain a practical strength, for example, a cellulose derivative, graphite, talc, inorganic fiber, silica, alumina, or the like may be used as a binder in an amount of 20 wt% or more, preferably about 50 wt%. However, the amount of catalyst is relatively reduced by the addition of the binder, and thus the catalyst loading is increased in order to maintain the desired reaction result. Thus, binders that provide practical catalyst strength at minimal addition levels are desirable.
The compression strength of the molded article obtained in this manner is, for example, 6.5 to 9.5 kgf. Preferably, it is 7.0 to 9.0 kgf. More preferably 7.0 to 8.0 kgf. By setting the compressive strength of the molded article to 6.5kgf or more, the occurrence of cracking and chipping during the charging into the fixed bed reactor and the operation can be suppressed. Further, when the compressive strength of the molded article is 9.5kgf or less, the yield at the beginning of the reaction (initial yield) is further improved.
Examples of the catalytic reaction include a reaction selected from the following: examples of the hydrogen treatment (hydrogenation) include hydrodesulfurization such as hydrodesulfurization and hydrogenation (hydrogenation), steam reforming such as prereforming, contact steam reforming, autothermal reforming, secondary reforming, and reforming processes used for direct reduction of iron, contact partial oxidation, aqueous gas shift such as isothermal shift, sulfur tolerant shift, low temperature shift, intermediate temperature shift, medium temperature shift, and high temperature shift, methanation synthesis by fischer-tropsch reaction, methanol synthesis, ammonia oxidation, nitrous oxide decomposition reaction, and selective oxidation-reduction reaction of exhaust gas from an internal combustion engine or a power station.
For such catalytic reactions, the catalytically active promoter may be further supported in an amount necessary to enhance activity. Examples of the loading method include the following methods: the solution containing the accelerator is added to the transition metal compound, and the mixture is dried while heating the mixture to, for example, 50 to 120 ℃ and stirring the mixture. The amount of the accelerator added is, for example, 1 to 50 times the molar amount of the transition metal. Preferably, the amount is 10 times the molar amount. More preferably 5 times the molar amount, or 3 times the molar amount.
In the case where the transition metal support of the present invention is used as a catalyst for ammonia synthesis, the ammonia synthesis reaction may be carried out, for example, in the following manner.
In order to react hydrogen and nitrogen using a gas containing hydrogen and nitrogen as a raw material, ammonia is synthesized by filling the catalyst for ammonia synthesis in a catalyst-filled layer in a reactor and then reacting the raw material gas on the catalyst layer present in the catalyst-filled layer.
In a typical embodiment of the ammonia synthesis reaction, a mixed gas of nitrogen and hydrogen is directly reacted under heat and pressure, and the reaction product is converted from N2+3H2→2NH3The ammonia produced by the reaction shown may be separated by cooling or by water absorption.
The nitrogen gas and the hydrogen gas are supplied so as to be in contact with a catalyst layer existing in a catalyst-packed layer provided in the reactor. Before supplying nitrogen and hydrogen gas, the surface of the catalyst layer is preferably subjected to a reduction treatment with hydrogen gas or a mixed gas of hydrogen and nitrogen, thereby removing oxides and the like adhering to the surface of the catalyst layer (i.e., the surface of the catalyst) in advance.
The reactor may be any of a batch reactor, a closed-cycle reactor, and a flow reactor, and from the viewpoint of practicality, a flow reactor is preferably used.
The ammonia synthesis reaction is preferably performed in an atmosphere containing as little moisture as possible, that is, in a dry nitrogen and hydrogen atmosphere having a water vapor partial pressure of about 0.1kPa or less.
Ammonia is synthesized by heating the transition metal support of the present invention as a catalyst in an atmosphere of a mixed gas of nitrogen and hydrogen as raw materials.
The ammonia synthesis reaction can be carried out under conditions such that the molar ratio of nitrogen to hydrogen is about 1/10 to 1/1. The reaction temperature is preferably, for example, room temperature to less than 500 ℃. More preferably 300 to 350 ℃. The lower the reaction temperature, the more favorable the reaction equilibrium is for ammonia production, but the reaction temperature is preferably in the above range in order to obtain a sufficient ammonia production rate and to make the reaction equilibrium favorable for ammonia production.
In the ammonia synthesis reaction, the reaction pressure of the mixed gas of nitrogen and hydrogen is not particularly limited, but is preferably 10kPa to 20MPa, more preferably 10kPa to 5 MPa. In view of practical use, the reaction pressure is preferably from atmospheric pressure to pressurized conditions, and more preferably from about 100kPa to 1.5 MPa.
The resulting ammonia-containing gas can be used to separate only ammonia as needed using known methods. Furthermore, the following recycling process may also be included: the remaining gas is further separated from the raw material gas and reused as the raw material gas.
As described above, the lanthanide series oxyhydroxide contained in the electron or negative hydrogen ion absorbing/releasing composition of the present invention may be a compound represented by formula (2), and the values of x and y in formula (2) may be always fixed or may vary within their ranges in terms of the composition ratio of each element in the lanthanide series oxyhydroxide of the present invention in the course of carrying out the method for producing ammonia of the present invention.
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