WO2024253202A1 - Composition for ammonia storage, ammonia bonding composition, ammonia storage device, ammonia storage method, and ammonia molecule removal method - Google Patents

Abstract

Provided are: a composition for ammonia storage and an ammonia bonding composition, with which ammonia can be stored relatively easily under mild conditions and can be stored with high safety; and an ammonia storage device and an ammonia storage method, which use same. The composition for ammonia storage contains a compound for ammonia storage which is represented by any of specific formulae (I-a) to (I-c). In addition, the ammonia bonding composition contains said composition for ammonia storage and is obtained by bonding the compound to an ammonia molecule and a water molecule. In addition, the ammonia storage device, the ammonia storage method and an ammonia molecule removal method use the foregoing.

Description

Ammonia storage composition, ammonia binding composition, ammonia storage device, ammonia storage method, and ammonia molecule removal method

The present invention relates to an ammonia storage composition using a material capable of chemically storing ammonia, an ammonia storage device using the same, an ammonia storage method, and a method for removing ammonia molecules.
This application claims priority to U.S. Patent Application No. 63/471,981, provisionally filed in the United States on June 9, 2023, the contents of which are incorporated herein by reference.

Ammonia (NH ₃ ) is an important chemical substance that is widely used as a raw material for fertilizers, medicines, fibers, food, etc., and about 200 million tons are produced annually worldwide. On the other hand, it has a large hydrogen mass density (17.8 wt%) and hydrogen volume density (0.107 kg/L), and is also attracting attention as a so-called hydrogen carrier. Another advantage is that it does not contain carbon and does not emit carbon dioxide when burned.

However, ammonia is a highly corrosive gas at room temperature and pressure, making it difficult to handle and store, so it is often liquefied to maximize storage density at low temperatures (such as -33°C) or stored in pressurized vessels at high pressures (16-18 bar).
Therefore, a safer and easier method of storing ammonia is desired. For example, porous materials have been investigated as a storage medium for ammonia. For example, materials such as activated carbon, zeolites, polymers, or metal-organic frameworks (porous metal complexes) can physically adsorb ammonia in their pores.

For example, US Pat. No. 5,999,633 discloses zeolite frameworks for gas separation, gas storage, catalysis and sensors. In particular, the document discloses a zeolite framework (ZIF) that comprises any number of transition metals or a homogeneous transition metal composition. The zeolite framework is capable of adsorbing chemical species, including ammonia, and is intended to be used to obtain a gas storage device, etc.

Special Publication No. 2009-528251

Storage media using porous materials such as those described in Patent Document 1 can store ammonia under mild conditions close to room temperature and pressure. However, all of these storage media have limited functionality, such as low storage capacity and irreversible uptake.

In addition, the principle of trapping ammonia in pores means that it is stored chemically as ammonia, so ammonia remains corrosive when stored at room temperature and pressure, raising safety concerns. For this reason, new ammonia storage materials are always desired.

The present invention has been made in consideration of the above circumstances, and its purpose is to provide an ammonia storage composition, an ammonia binding composition, an ammonia storage device using the same, an ammonia storage method, and a method for removing ammonia molecules, which allow ammonia to be stored relatively easily under mild conditions and with a high degree of safety.

In order to solve the above problems, the present invention has the following aspects.
[1] Any of the following formulas (I-a) to (I-c):
PbI ₂ ... (I-a)
RPbX ₃ ... (I-b)
R _n+1 Pb _n X _3n+1 ... (I-c)
(In the formula (I-b) and the formula (1-c), R represents ammonium, guanidinium or formamidinium containing a hydrocarbon group having 1 to 10 carbon atoms which may be substituted, X represents a halogen element, and when the formula contains two or more Rs, they may be the same or different, and n represents a natural number), comprising at least one ammonia storage compound represented by the formula (I-b) and the formula (1-c).
[2] The ammonia storage compound is
R ₁ NH ₃ PbI ₃ ... (I-d)
(In the formula (I-d), R ₁ is a hydrocarbon group having 1 to 10 carbon atoms which may be substituted.)
The ammonia storage composition according to [1],
[3] An ammonia-binding composition comprising the ammonia storage composition according to [1], wherein an ammonia molecule and a water molecule are further bound to the compound.
[4] An ammonia storage device comprising the ammonia storage composition according to [1] or [2],
A first retention member for retaining the ammonia storage composition;
The ammonia storage composition held in the first holding member is contacted with ammonia molecules and water under conditions of an ammonia binding pressure P1 and an ammonia binding temperature T1,
The ammonia storage device further comprises a means for further binding ammonia molecules and water molecules to the at least one ammonia storage compound to obtain an ammonia-binding composition.
[5] A second holding member for holding the ammonia-binding composition;
The ammonia-binding composition held in the second holding member is treated under conditions of an ammonia desorption pressure P2 and an ammonia desorption temperature T2 to desorb ammonia molecules from the ammonia-binding composition to obtain at least one ammonia storage compound;
The ammonia storage device according to [4], further comprising a means for collecting ammonia molecules released from the ammonia-binding composition.
[6] The ammonia binding temperature T1 and the ammonia desorption temperature T2 have a relationship of T2>T1,
The ammonia binding pressure P1 and the ammonia desorption pressure P2 have a relationship of P2<P1.
The ammonia storage device according to [5].
[7] A method for storing ammonia, comprising:
Any of the following formulas (I-a) to (I-c):
PbI ₂ ... (I-a)
RPbX ₃ ... (I-b)
R _n+1 Pb _n X _3n+1 ... (I-c)
(In the formula (I-b) and formula (1-c), R represents an ammonium, guanidinium or formamidinium containing a hydrocarbon group having 1 to 10 carbon atoms which may be substituted, X represents a halogen element, and when the formula contains two or more Rs, they may be the same or different, and n represents a natural number.)
For at least one ammonia storage compound represented by
An ammonia storage method comprising: an ammonia storage step of contacting ammonia molecules and water molecules under conditions of an ammonia binding pressure P1 and an ammonia binding temperature T1 to cause a chemical reaction.
[8] The ammonia storage compound is
R ₁ NH ₃ PbI ₃ ... (I-d)
(In the formula (I-d), R ₁ is a hydrocarbon group having 1 to 10 carbon atoms which may be substituted.)
The ammonia storage method according to [7],
[9] The ammonia storage method according to [7], comprising an ammonia desorption step of treating the ammonia-binding composition under conditions of an ammonia desorption pressure P2 and an ammonia desorption temperature T2 to liberate ammonia molecules from the ammonia-binding composition.
[10] The ammonia binding temperature T1 and the ammonia desorption temperature T2 have a relationship of T2>T1,
The ammonia binding pressure P1 and the ammonia desorption pressure P2 have a relationship of P2<P1.
The method for storing ammonia according to [9].
[11] Any of the following formulas (I) to (III):
PbI ₂ ... (I-a)
RPbX ₃ ... (I-b)
R _n+1 Pb _n X _3n+1 ... (I-c)
(In the formula (I-b) and formula (1-c), R represents an ammonium, guanidinium or formamidinium containing a hydrocarbon group having 1 to 10 carbon atoms which may be substituted, X represents a halogen element, and when the formula contains two or more Rs, they may be the same or different, and n represents a natural number.)
A method for removing ammonia molecules, comprising: contacting a gas phase containing at least ammonia molecules and water molecules with an ammonia storage composition containing at least one ammonia storage compound represented by the formula:
[12] The ammonia storage compound,
R ₁ NH ₃ PbI ₃ ... (I-d)
(In the formula (I-d), R ₁ is a hydrocarbon group having 1 to 10 carbon atoms which may be substituted.)
The method for removing ammonia molecules according to [11],

The present invention provides an ammonia storage composition that allows ammonia to be stored relatively easily under mild conditions and with a high degree of safety, an ammonia storage device that uses the composition, an ammonia storage method, and a method for removing ammonia molecules.

FIG. ₁ is a photograph of the appearance of the synthesized EAPbI3 and the test of ammonia uptake. _{FIG. 1} is a schematic diagram of the crystal structures of EAPbI3 and Pb(OH)I. FIG _{. 1 is a photograph of EAPbI3} and Pb(OH)I observed by optical microscope. FIG. ₁ is a schematic diagram showing the arrangement of EAPbI3 crystals. FIG. 2 is another schematic diagram showing the arrangement of Pb(OH)I crystals. _{FIG. 2} is a graph showing the adsorption isotherm and TG-MS results of EAPbI3. FIG. 2 is a photograph of the sample of this embodiment when subjected to X-ray analysis. FIG. ₂ is a graph showing the change in the XRD pattern of EAPbI3. FIG. ₂ is a graph showing the X-ray diffraction pattern of EAPbI3. FIG. 2 is a schematic diagram showing the spacings of d001 and d002 in a crystal structure. FIG. ₁ is a photographic diagram showing repeated _NH3 uptake/extraction of EAPbI3. FIG. 12 is a graph showing XRD patterns of _EAPbI3 in the states (i), (iii), and (v) in FIG. FIG. 1 is a schematic diagram showing a putative mechanism of _NH3 storage proposed to explain the reversible structural changes upon _NH3 uptake/extraction. _{FIG. 2} is a graph showing NMR spectra of EAPbI3 before and after _NH3 incorporation. FIG. 2 is a graph showing XRD patterns of PbI ₂ and EAI. FIG. 2 is a graph showing an XRD pattern of Pb(OH)I. 2 is a schematic diagram showing the action of an ammonia storage compound contained in the ammonia storage composition of the present embodiment. FIG. FIG. 1 is a photograph showing the vapor discoloration behavior of _EAPbI3 crystals stamped on paper to _NH3 vapor. Figure ₂ shows a scanning electron microscope (SEM) image of EAPbI3 crystals layered on paper. FIG. ₂ is a graph showing the change in diffuse reflectance spectrum of EAPbI3 immersed in paper at 25° C. FIG. ₁ is a graph showing the Tauc plot of EAPbI3. FIG. ₂ is a graph showing the fluorescence spectrum of EAPbI3 immersed in paper at 25 °C. FIG. 1 is a graph showing the change in the fluorescence spectrum of paper-soaked samples at various concentrations of _NH3 . FIG. 1 is a graph showing the relationship between the rate of change of fluorescence intensity at 545 nm and _NH3 concentration. FIG. ₁ is a graph showing the change in response time depending on the sample thickness of EAPbI3. FIG. 1 is a photographic diagram showing the adsorption behavior of various solutions onto soaked EAPbI3 _crystals on paper. FIG. 2 is a graph showing the NMR spectrum of CH ₃ CH ₂ NH ₃ I. _{FIG. 2} is a graph showing the _{NMR spectrum of CH3CH2NH3PbI3 .} FIG. 1 is a schematic diagram of an ammonia storage device according to an embodiment of the present invention. FIG. 1 is a photograph showing the adsorption behavior of various solutions onto crystals of other compounds. FIG. 2 is a graph showing adsorption isotherms for other compounds. FIG. 2 is another graph showing adsorption isotherms for other compounds. FIG. 2 is another graph showing adsorption isotherms for other compounds. FIG. 1 is a graph showing the results of thermogravimetric mass spectrometry for other compounds. FIG. 11 is another graph showing the results of thermogravimetric mass spectrometry for other compounds. FIG. 11 is another graph showing the results of thermogravimetric mass spectrometry for other compounds.

The following describes the ammonia storage composition according to the present invention, and the ammonia storage device and ammonia storage method using the same, with reference to the following embodiments. However, the present invention is not limited to the following embodiments.

(Ammonia storage composition)
The ammonia storage composition of the present embodiment is
Any of the following formulas (I-a) to (I-c):
PbI ₂ ... (I-a)
RPbX ₃ ... (I-b)
R _n+1 Pb _n X _3n+1 ... (I-c)
(In the formulae (I-b) and (I-c), R represents an ammonium, guanidinium or formamidinium containing a hydrocarbon group having 1 to 10 carbon atoms which may be substituted, X represents a halogen element, and when the formula contains two or more Rs, they may be the same or different, and n represents a natural number.)
The compound includes at least one compound represented by the formula (hereinafter, sometimes referred to as "ammonia storage compound").

In formula (I-c), n represents a natural number, and the number is not particularly limited, but is, for example, 1 to 20, preferably 1 to 10 or 1 to 7, and more preferably 1 to 5. Examples of the compound represented by formula (I-c) include layered perovskite. When the compound represented by formula (I-c) is a layered perovskite, n may be equal to the number of layers.
In formulae (I-b) and (I-c), the optionally substituted hydrocarbon group represented by R may be chain-like, and in the case of chain-like, it may be either linear or branched, or a combination thereof, or it may be cyclic (i.e., a cycloalkyl group). R may have aromaticity, or may be a combination of an aromatic hydrocarbon group (e.g., a phenyl group) and an aliphatic hydrocarbon group (e.g., an alkyl group). Among these, R is preferably an alkyl group or araalkyl group (e.g., a phenylalkyl group) having 1 to 10 carbon atoms which may be substituted.
R is a hydrocarbon group which may be substituted, and examples of the substituent include both hydrophilic and hydrophobic substituents. Examples of the hydrophilic substituent include an amino group and a hydroxyl group. Examples of the hydrophobic substituent include a halogen atom (e.g., a fluorine atom).

In formula (Ic), R may be a guanidinium or formamidinium represented by the following formula (C1) or (C2).

The compound represented by formula (I-c) contains two or more R. The two or more R may be the same or different.

In terms of chemical structure, formula (I-a) is a metal halide, formula (I-b) is obtained by partially substituting formula (I-a), and formula (I-c) is obtained by partially substituting formula (I-a), which form a layered perovskite compound (where n generally indicates the layered structure of perovskite).

The ammonia storage compound is
R ₁ NH ₃ PbI ₃ ... (I-d)
(In the formula (I-d), R ₁ is a hydrocarbon group having 1 to 10 carbon atoms which may be substituted.)
In particular, the compound is represented by the formula:
The structure and substituents of R ₁ can be selected from those similar to those of R described above.

"Storing ammonia" refers to a use in which a compound or composition can be used to bind with ammonia through a chemical reaction or the like and stably retain ammonia. "Storing stably" preferably means that the compound is almost chemically stable in the state bound to ammonia at normal temperature, normal pressure, etc.

It is preferable that the ammonia storage compound and composition can be bonded to ammonia by a certain operation such as by chemical reaction, and can be dissociated from ammonia by another certain operation.
In this embodiment, a composition containing at least one type of compound obtained by, for example, chemically reacting an ammonia storage compound with ammonia is referred to as an ammonia-binding composition.
That is, at least one of the compounds of formulae (I-a) to (I-d) may be bound to an ammonia molecule and a water molecule by a chemical reaction. An example of this embodiment is an ammonia-binding composition obtained by chemically reacting _PbI2 and RPbX (e.g., _R1NH3I ) that are in chemical equilibrium with the ammonia storage compound, for example, a compound of formula (I- _b ), with a water molecule and an ammonia molecule, respectively. In this example, the ammonia-binding composition includes at least one of _R1NH2 and _NH4I that are generated by chemically reacting an _{ammonia molecule} with at least one of _R1NH3I , and includes Pb(OH)I and HI that are obtained by reacting _PbI2 with a water molecule.

In this specification, the state in which a material containing an ammonia storage composition contains ammonia as a result of an ammonia storage compound or composition chemically reacting with ammonia and bonding with it is sometimes referred to as ammonia uptake. In addition, the state in which a material containing an ammonia storage composition changes from a state in which it contains ammonia to a state in which it does not contain ammonia as a result of an ammonia storage compound or composition dissociating from ammonia, or the removal of ammonia from the material is sometimes referred to as ammonia extraction.

In formulas (I-b) and (I-c), R is a hydrocarbon group having 1 to 10 carbon atoms which may be substituted, and may be either linear or branched, and any of the hydrogen atoms may be substituted with other elements. However, from the perspective of the crystal structure of the ammonia storage compound described below, it is preferable that the carbon number is 1 to 5.

Formula (Id) is a compound of formula (Ib) in which R has a specific structure, and R has a hydrocarbon group _R1 , one of which is substituted with an amino group.
In formula (I-d), R ₁ is more preferably an ethyl group having two carbon atoms (CH ₃ CH ₂ --). That is, it is more preferable that the ammonia storage compound is of formula (II): CH ₃ CH ₂ NH ₃ PbI ₃ (when R ₁ is an ethyl group, this is also called ethylammonium lead iodide: EAPbI ₃ ).

More specifically, the ammonia storage compound is preferably a compound of the following formulas (II) to (XI):

_{CH3CH2NH3PbI3 ... ( II} )
(Ethylammonium lead iodide, EAPbI ₃ )
_{CF3CH2NH3PbI3 ...} ( _{III )}
(Trifluoroethylammonium lead iodide, FEAPbI ₃ )

（Ｆｏｒｍａｍｉｄｉｎｉｕｍ ｌｅａｄ　ｂｒｏｍｉｄｅ　（ＦＡＰｂＢｒ_３））

（Ｇｕａｎｉｄｉｎｉｕｍ　ｌｅａｄ　ｉｏｄｉｄｅ　（ＧｕａＰｂｌ_３））

（Ｄｉｂｕｔｙｌａｍｍｏｎｉｕｍ　ｌｅａｄ　ｔｅｔｒａｉｏｄｉｄｅ　（（ＢＡ）_２ＰｂＩ_４））

（Ｄｉｂｕｔｙｌａｍｍｏｎｉｕｍ　ｌｅａｄ　ｔｅｔｒａｂｒｏｍｉｄｅ　（（ＢＡ）_２ＰｂＢｒ_４））

(Formamidinium lead bromide ( _FAPbBr3 ))

(Guanidinium lead iodide (GuaPbl ₃ ))

(Dibutylammonium lead tetraiodide ((BA) ₂ PbI ₄ ))

(Dibutylammonium lead tetrabromide ((BA) ₂ PbBr ₄ ))

Ｄｉｐｈｅｎｙｌｅｔｈｙｌａｍｍｏｎｉｕｍ　ｌｅａｄ　ｔｅｔｒａｉｏｄｉｄｅ　（（ＰＥＡ）_２ＰｂＩ_４）

Ｄｉｐｈｅｎｙｌｅｔｈｙｌａｍｍｏｎｉｕｍ　ｌｅａｄ　ｔｅｔｒａｂｒｏｍｉｄｅ　（（ＰＥＡ）_２ＰｂＢｒ_４）

Ｄｉｂｕｔｙｌａｍｍｏｎｉｕｍ　ｍｅｔｈｙｌａｍｍｏｎｉｕｍ　ｌｅａｄ　ｈｅｐｔａｉｏｄｉｄｅ　
（（ＢＡ）_２（ＭＡ）Ｐｂ_２Ｉ_７）

Diphenylethylammonium lead tetraiodide ((PEA) ₂ PbI ₄ )

Diphenylethylammonium lead tetrabromide ((PEA) ₂ PbBr ₄ )

Dibutylammonium methylammonium lead heptaiodide
((BA) ₂ (MA)Pb ₂ I ₇ )

Ｄｉｂｕｔｙｌａｍｍｏｎｉｕｍ　ｄｉｍｅｔｈｙｌａｍｍｏｎｉｕｍ　ｌｅａｄ　ｄｅｃａｉｏｄｉｄｅ
（（ＢＡ）_２（ＭＡ）_２Ｐｂ_３Ｉ_１０）

Ｄｉｂｕｔｙｌａｍｍｏｎｉｕｍ　ｔｒｉｍｅｔｈｙｌａｍｍｏｎｉｕｍ　ｌｅａｄ　ｔｒｉｄｅｃａｉｏｄｉｄｅ
（（ＢＡ）_２（ＭＡ）_３Ｐｂ４Ｉ_１３）

Ｄｉｂｕｔｙｌａｍｍｏｎｉｕｍ　ｔｅｔｒａｍｅｔｈｙｌａｍｍｏｎｉｕｍ　ｌｅａｄ　ｈｅｘａｄｅｃａｉｏｄｉｄｅ
（（ＢＡ）_２（ＭＡ）_４Ｐｂ_５Ｉ_１６）

Dibutylammonium dimethylammonium lead decaiodide
((BA) ₂ (MA) ₂ Pb ₃ I ₁₀ )

Dibutylammonium trimethylammonium lead tridecaiodide
((BA) ₂ (MA) ₃ Pb4I ₁₃ )

Dibutylammonium tetramethylammonium lead hexadecaiodide
((BA) ₂ (MA) ₄ Pb ₅ I ₁₆ )

_{CH3CH2NH3PbBr3 ... ( XIV} )
(Ethylammonium lead bromide, EAPbBr ₃ )
HOCH ₂ CH ₂ NH ₃ PbI ₃ ... (XV)
((2-Hydroxyethyl)ammonium lead Iodide, HOEAPbI ₃ )

When the ammonia storage compound is a compound of formula (Ib) or (Id), it is preferable that the compound has a one-dimensional (1D) columnar structure at room temperature and normal pressure.
Specifically, when the ammonia storage compound is CH ₃ CH ₂ NH ₃ PbI ₃ (EAPbI ₃ ), as shown in FIG. 2(i) of the Example described later, CH ₃ CH ₂ NH ₃ ⁺ cations are molecular-packed between 1D columnar structures of [PbI ₆ ] ^4- octahedrons.

Furthermore, in this specification, perovskite materials made of compounds containing an organic substance (R, ammonia), an inorganic substance (Pb), and a halide (e.g., I (iodine)), including the ammonia storage compound of this embodiment, are also referred to as organic-inorganic halide perovskite (organic-inorganic halide perovskite, organometallic halide perovskite) materials, etc.

Ammonia-binding Composition
The ammonia-binding composition of this embodiment is a composition containing a chemical species obtained by binding ammonia molecules and water molecules to the ammonia storage compound through a chemical reaction or the like. One example is an ammonia-binding composition obtained as a result of water molecules and ammonia molecules being bound to each of compounds in chemical equilibrium with the ammonia storage compound (for example, PbI ₂ and R ₁ NH ₃ I in the case of formula (I-d)) through chemical reaction. In this example, the ammonia-binding composition contains at least one of RNH ₂ and NH ₄ I that are generated by the chemical reaction of ammonia molecules with at least one of RNH ₃ I, and Pb(OH)I and HI that are obtained by the reaction of PbI ₂ with water molecules.

The ammonia-binding composition holds ammonia molecules in a state in which they can be released by chemical reaction or the like. The chemical reaction is the reverse reaction of the reaction that occurs when the ammonia storage compound bonds with ammonia molecules (and water molecules). In other words, the ammonia storage composition takes in ammonia by chemical reaction, and the ammonia-binding composition obtained thereby releases ammonia by chemical reaction.

Specifically, for example, when the ammonia storage compound R ₁ NH ₃ PbI ₃ of formula (Id) is exposed to NH ₃ (aq) vapor under certain conditions, Pb(OH)I containing OH- anions becomes an ammonia ^- binding compound in which ammonia is incorporated between the molecules.
More preferably, when the ammonia storage compound is CH ₃ CH ₂ NH ₃ PbI ₃ (also called EAPbI ₃ ), a chemical structure change occurs from the one-dimensional (1D) columnar structure CH ₃ CH ₂ NH ₃ PbI ₃ (EAPbI ₃ ) to the two-dimensional (2D) layered structure Pb(OH)I, and NH ₃ is incorporated between the layers.

(Ammonia storage device)
The ammonia storage device of the present embodiment includes the ammonia storage composition described above.
29 is a schematic diagram of the ammonia storage device 100 of this embodiment. As shown in the figure, the ammonia storage device 100 of this embodiment includes a first holding member 11 for holding an ammonia storage composition 1, and a means for contacting the ammonia storage composition 1 held in the first holding member 11 with ammonia molecules and water under conditions of an ammonia binding pressure P1 and an ammonia binding temperature T1 to obtain an ammonia-bound composition 2 containing a chemical species obtained by further binding ammonia molecules and water molecules to the at least one ammonia storage compound.

The ammonia storage device 100 is a device that stores ammonia in the ammonia storage composition 1 by bringing ammonia molecules into contact with the ammonia storage composition 1 .
The ammonia storage composition 1 may be in any form as long as it can be held in the first holding member 11. For example, if the first holding member 11 is a container, the ammonia storage composition 1 may be in any form as long as it can be placed in the container.

The first holding member 11 is a member that holds the ammonia storage composition 1 and is configured to allow ammonia molecules and water to come into contact with the ammonia storage composition 1 under conditions of an ammonia binding pressure P1 and an ammonia binding temperature T1 within the bonding treatment member 12 described below. Such a member is preferably a member that allows gas to pass through, for example, by having one or more surfaces open or being communicable. As described below, water is preferably water vapor, so it is sufficient that the member is capable of passing gas. An example of the first holding member 11 is a container that can hold the ammonia storage composition 1 and that can be stored in the bonding treatment member 12.

The binding treatment member 12 is a means for contacting the ammonia storage composition 1 held in the first holding member 11 with ammonia molecules and water under conditions of an ammonia binding pressure P1 and an ammonia binding temperature T1 to obtain an ammonia-binding composition containing a chemical species generated by further binding ammonia molecules and water molecules to the ammonia storage compound. In this embodiment, the binding treatment member 12 is a container capable of containing the first holding member 11.
The binding processing member 12 is a container that can be opened to accommodate and remove the first holding member 11, and can also be sealed. By being able to seal, the inside of the container of the binding processing member 12 can be kept under the conditions of an ammonia binding pressure P1 and an ammonia binding temperature T1, and ammonia molecules and water can be brought into contact with the ammonia storage composition 1 for a certain period of time under certain conditions (such as a certain vapor pressure).

In this embodiment, the bonding processing member 12 includes a pressure control means (not shown) capable of maintaining the inside of the container at an ammonia bonding pressure P1, a temperature control means (not shown) capable of maintaining the inside of the container at an ammonia bonding temperature T1, an ammonia supply means (not shown) capable of supplying ammonia molecules into the container, and a water supply means (not shown) capable of supplying water (water vapor) into the container.
The preferred conditions for the ammonia binding pressure P1, the ammonia binding temperature T1, and the contact of ammonia with water will be described later in the ammonia storage method.

In this embodiment, the ammonia storage device preferably further comprises a second holding member 21 for holding the ammonia-binding composition 2, a means for treating the ammonia-binding composition 2 held in the second holding member 21 under conditions of an ammonia desorption pressure P2 and an ammonia desorption temperature T2 to desorb ammonia molecules from the ammonia-binding composition 2 and convert them into at least one compound of formula (I), and a means for collecting the ammonia molecules liberated from the ammonia-binding composition 2.

The second holding member 21 and the release processing member 22 described below are members that have the function of releasing (extracting) ammonia from the ammonia-binding composition 2 and extracting the ammonia. In other words, after the ammonia storage composition 1 is bound to ammonia by the first holding member 11 and the binding processing member 12 to become the ammonia-binding composition 2, they are members that extract ammonia from the ammonia-binding composition 2.

The second holding member 21 has the same configuration as the first holding member 11. That is, it is a member that is capable of holding the ammonia-binding composition 2 and is configured so that the held ammonia-binding composition 2 can be placed under the conditions of ammonia binding pressure P1 and the ammonia desorption pressure P2 in the desorption treatment member 22 described below. In this embodiment, a container that allows gas to pass through is used.

The desorption processing member 22 is a member equipped with a means for treating the ammonia-binding composition 2 held in the second holding member 21 under conditions of an ammonia desorption pressure P2 and an ammonia desorption temperature T2 to liberate ammonia from the ammonia-binding composition and obtain the liberated ammonia molecules. In this embodiment, the desorption processing member 22 is a container capable of containing the second holding member 21.
The desorption processing member 22 is a container that can be opened to accommodate and remove the second holding member 21, and can also be sealed. By being able to be sealed, the inside of the container of the desorption processing member 22 can be maintained under the conditions of an ammonia desorption pressure P2 and an ammonia desorption temperature T2.

In this embodiment, the desorption processing member 22 is provided with a pressure control means (not shown) capable of maintaining the inside of the container at an ammonia desorption pressure P2, and a temperature control means (not shown) capable of maintaining the inside of the container at an ammonia desorption temperature T2. Also, the desorption processing member 22 is provided with an ammonia storage means for storing the ammonia recovered from the ammonia-binding composition 2. For example, when the pressure control means provided in the desorption processing member 22 is a negative pressure device, the negative pressure device may be connected to the ammonia storage means.
The ammonia desorption pressure P2 and the ammonia desorption temperature T2 will be described later in the ammonia storage method. However, it is preferable that the ammonia binding temperature T1 and the ammonia desorption temperature T2 have a relationship of T2>T1, and the ammonia binding pressure P1 and the ammonia desorption pressure P2 have a relationship of P2<P1.

(Method of storing ammonia)
The ammonia storage method of this embodiment includes a process (hereinafter sometimes referred to as the "ammonia storage process") of contacting the ammonia storage compound with ammonia molecules and water under conditions of an ammonia binding pressure P1 and an ammonia binding temperature T1 to cause a chemical reaction.
An example of this embodiment includes a process in which water and ammonia molecules are reacted with _PbI2 and _RNH3I , respectively, which are in chemical equilibrium with at least one compound of formula (I). In this example, the ammonia molecules react with at least one _RNH3I to produce at least one _RNH2 and _NH4I , and the _PbI2 reacts with water molecules to produce Pb(OH)I and HI. The ammonia molecules are stored by forming at least one or both of _RNH2 and _NH4I molecules.

The ammonia storage method of this embodiment is preferably carried out using the ammonia storage device described above. The ammonia storage compound may be any of those described above.

(Storage conditions)
The ammonia bonding pressure P1 must be 80 mbar or more at room temperature (25° C.), and is preferably normal pressure (1 bar) or less. The bonding between the ammonia storage compound and ammonia does not necessarily require high pressure, but bonding is difficult to occur if the pressure is below the lower limit.

The ammonia binding temperature T1 is preferably equal to or higher than room temperature (25° C.), and more preferably equal to or higher than 40° C. Even at room temperature, the ammonia storage compound and ammonia will bind together at the above-mentioned high pressure, but the higher the temperature, the more efficient the binding.
The ammonia binding temperature T1 must be equal to or lower than 90° C. The binding efficiency reaches a maximum at 90° C., but decreases at temperatures higher than this.

The step of contacting molecular ammonia and water is preferably carried out by exposure to NH ₃ (aq) vapor.
The content (partial pressure) of NH ₃ (aq) vapor during exposure can be appropriately selected so long as it is contained in the exposure gas, but it is preferably 10% or more of the saturated vapor pressure, and it is more preferable to use saturated NH ₃ (aq) vapor.
The exposure time is preferably 5 minutes or more, more preferably 10 minutes or more, and even more preferably 1 hour or more.

(Conditions for withdrawal)
The ammonia storage method of the present embodiment may include a step of releasing ammonia after the storage step. For example, the release step is a step of treating an ammonia-binding composition containing a chemical species obtained by chemically reacting at least one compound of formula (I) (ammonia storage compound) with water molecules and ammonia molecules under conditions of an ammonia release pressure P2 and an ammonia release temperature T2 to liberate ammonia molecules from the ammonia-binding composition.
In one example, the ammonia-binding composition includes at least one of _RNH2 and _NH4I , which are produced by chemically reacting an ammonia molecule with at least one of _RNH3I , and Pb(OH)I and HI, which are produced by reacting _PbI2 with a water molecule, and ammonia molecules are liberated by the reverse reaction of the chemical reaction that occurs in the ammonia storage process.

The conditions of the ammonia desorption pressure P2 and the ammonia desorption temperature T2 are generally higher or lower than those in the ammonia storage step, and preferably higher and lower.
The ammonia desorption pressure P2 is preferably less than 300 mbar, more preferably less than or equal to 80 mbar, and even more preferably approximately a vacuum.
The ammonia desorption temperature T2 is preferably 40° C. or higher, and more preferably 50° C. or higher.
The duration of the ammonia desorption operation is preferably 10 minutes or more, more preferably 1 hour or more, and even more preferably 3 hours or more.

It is also preferable to select the values of T1, T2, P1, and P2 so that the ammonia binding temperature T1 and the ammonia desorption temperature T2 have a relationship of T2>T1, and the ammonia binding pressure P1 and the ammonia desorption pressure P2 have a relationship of P2<P1.

The ammonia storage process and the ammonia desorption process can be carried out in any suitable combination. For example, ammonia can be stored in the ammonia storage composition in the ammonia storage process, and then ammonia can be obtained from the ammonia-bound composition at any time by the ammonia desorption process.

(Method of Removing Ammonia Molecules)
The method for removing ammonia molecules of this embodiment is a method for removing ammonia molecules, comprising the step of contacting an ammonia storage composition containing at least one compound (ammonia storage compound) represented by formula (I): RNH ₃ PbI ₃ (wherein R is a C ₁ to C ₁₀ hydrocarbon group) with a gas phase containing at least ammonia molecules and water molecules, thereby chemically reacting at least some of the ammonia molecules and water molecules in the gas phase with the at least one compound. The ammonia storage composition and chemical reaction usable in this embodiment are similar to those in the above-mentioned embodiment.

The method for removing ammonia molecules according to the present embodiment is used, for example, to remove ammonia molecules floating in a room. When the above-mentioned chemical reaction is accompanied by a color change, the degree of removal of ammonia can be known from the color change. In addition, the color change can also be used to detect ammonia molecules present in a room or the like.
This method for removing ammonia molecules can also be applied to a deodorizing method, and a deodorizing member or device using the same.

(Effects of this embodiment)
According to the present embodiment, it is possible to provide an ammonia storage composition that enables ammonia to be stored relatively easily under mild conditions and with high safety, an ammonia storage device using the same, an ammonia storage method, and a method for removing ammonia molecules.

The ammonia storage composition of this embodiment is easy and safe to operate, without requiring extreme conditions such as extremely high temperature and high pressure or low temperature and low pressure during storage and release operations. In addition, since the ammonia is chemically bonded to the ammonia storage compound, it is chemically stable in the bonded state and is safe during storage.

In general, in the chemical field, structural changes of dimensionally ordered structures of compounds have attracted much attention due to the changes in their chemical and physical properties. These compounds have been known to show modulation of molecular packing in response to external stimuli (light, ions, pH, chemical species, etc.). Dynamic modulation of chemical structures is expected to be useful for applications such as selective reaction sites, molecular structure, separation, gas adsorption, actuation, photocatalysis, and superlattices.
However, large changes in the chemical structure can lead to structural instability due to mechanical strain, and therefore the structural integrity and reversibility of the chemical structure remain key challenges in dynamic processes.

Here, the inventors have discovered the first chemical _NH3 storage in an organic-inorganic halide perovskite material through dynamic structure transformation. As shown in the examples below, the incorporation of _NH3 into the one-dimensional (1D) columnar structure of _{ethylammonium} lead _iodide ( _{CH3CH2NH3PbI3} , _EAPbI3 ) induces a structure transformation into the two-dimensional (2D) layered structure Pb(OH)I. The incorporation of _NH3 reaches 10.2 mmol/g at 1 _bar and 25°C. Heating at 50°C under vacuum causes the extraction of _NH3 , and the structure returns to the initial _EAPbI3 structure.
The novelty of this approach is that it uses a chemical reaction to store _NH3 . Unlike physical methods such as storage in pores, the chemical method has the potential to selectively store only _NH3 from a gas mixture through a chemical reaction. This method of capturing and extracting _NH3 is promising as a new type of _NH3 storage method.

The key to this technology is that the structural change is achieved by steam annealing. This is a property of organic-inorganic halide perovskite (organic inorganic halide perovskite, organometallic halide perovskite) materials. For example, steam annealing of methylammonium lead iodide, known as a three-dimensional (3D) perovskite material, leads to improved photoelectric conversion efficiency, increased carrier mobility, and enables chemical detection. Methylammonium lead iodide has the advantage that its structure is deformed in water vapor due to infiltration into the 3D structure, and therefore dimensional control of the chemical structure is important for steam annealing. 1D perovskite materials are expected to prevent modulation of the chemical structure, since the reduction in the dimensionality of the structure promotes relaxation of the chemical structure. In addition, the formation of molecular-sized spaces in the columnar structure can allow _NH3 vapor to be incorporated into the 1D structure.

The present inventors have discovered an organic-inorganic halide perovskite material capable of chemically storing ammonia through dynamic structural transformation. Upon uptake of ammonia, the material undergoes a chemical structural change from a one-dimensional columnar structure CH ₃ CH ₂ NH ₃ PbI ₃ (EAPbI ₃ ) to a two-dimensional layered structure Pb(OH)I. The ammonia uptake of this material is estimated to be 10.2 mmol/g at 1 bar and 25° C. Furthermore, ammonia extraction can be achieved by heating at 50° C. under vacuum. X-ray diffraction analysis reveals that the reversible uptake and extraction of ammonia originates from a cation/anion exchange reaction between CH ₃ CH ₂ NH ₃ ⁺ cations coordinated to [PbI ₆ ] ^4- octahedra and OH ^- anions stabilized by [OHPb ₃ ] tetrahedra.
This structural change indicates the possibility of integrating efficient uptake and extraction into hybrid perovskite materials through chemical reactions. These findings are also expected to pave the way for further exploration of dynamic, reversible and functionally useful materials for the chemical storage of ammonia.

Chemical ammonia storage has been realized by dynamic structural changes in organic-inorganic halide perovskite materials. Upon uptake of ammonia, the chemical structure changed from 1D columnar _EAPbI3 to 2D layered Pb(OH)I at 25 °C. Furthermore, upon heating at 50 °C under vacuum, ammonia extraction occurred due to the structural change to the initial halide perovskite EAPbI3. Single crystal XRD analysis revealed that the reversible change in chemical structure originated from cation/anion _exchange reactions with ammonia uptake/extraction. Because perovskite materials can capture ammonia through chemical reactions, this uptake and extraction method is expected to be able to selectively store ammonia from gas mixtures.

The inventors also found that metal halides, which are precursors (materials) of perovskite, and layered perovskite, which are related substances of the perovskite material, have ammonia storage performance. As shown in the examples below, the uptake of _NH3 was 7.1 mmol/g or more at 1 bar and 25°C, and reached 10.5 mmol/g in particularly excellent cases. When heated under vacuum, _NH3 is extracted and the initial structure is restored.
The novelty of this approach is that it uses a chemical reaction to store _NH3 . Unlike physical methods such as storage in pores, the chemical method has the potential to selectively store only _NH3 from a gas mixture through a chemical reaction. This method of capturing and extracting _NH3 is promising as a new type of _NH3 storage method.

The above describes an embodiment of the present invention, but the present invention is not limited to the above embodiment and various modifications can be made.

The effects of the present invention will be made clearer by the following examples and comparative examples. Note that the present invention is not limited to the following examples, and can be modified as appropriate without departing from the gist of the present invention.

[Test conditions]
The conditions for various measurements and operations were as follows:
(Structural Identification)
The synthesized compounds were identified by 1H NMR spectroscopy (JNM-ECZ400R, JEOL Ltd., Tokyo, Japan), high-resolution mass spectrometry (QSTAR Elite, AB SCIEX, Framingham, MA, USA), and elemental analysis. Surface morphology was investigated by SEM (Quattro ESEM, accelerating voltage 5 kV, Thermo Fisher Scientific, Waltham, MA, USA). Thermal properties were evaluated by TG analysis (TA-60WS, heating rate 10 °C/min under nitrogen, Shimadzu Corporation, Kyoto, Japan).

(Ammonia storage)
The uptake behavior of ammonia (NH ₃ ) was investigated using a gas adsorption system (BELSORP-max II-HV, MicrotracBEL Co., Ltd., Osaka, Japan). EAPbI ₃ (62 mg), preactivated at 60° C. for 3 h to remove any residual solvent, was transferred to a pre-weighed analysis tube. The tube containing the sample was weighed again to measure the mass of the sample. The tube was purged with nitrogen and transferred to the analysis port. Adsorption isotherms were measured at 25° C. using ammonia gas (99.9% purity, Sumitomo Seika Chemicals Co., Ltd., Osaka, Japan). Ammonia extraction was investigated by TG-MS analysis (ThermoMass Photo, mass range m/z = 1-300, Rigaku Co., Ltd., Tokyo, Japan). The sample (6.0 mg) in which ammonia was stored was placed on the TG sample holder. Thermally evaporated species were detected by electron ionization spectroscopy under a helium gas flow of 200 mL/min at a heating rate of 5°C/min. Ammonia extraction behavior was evaluated using a vacuum oven (VOM-1000A, EYELA Co., Ltd., Tokyo, Japan) at 50°C.

(X-ray measurement)
Powder XRD data were acquired on a SmartLab diffractometer (Rigaku Corporation) using Cu Kα (λ = 1.5418 Å) or Cu Kα1 (λ = 1.5405 Å) radiation. Samples were placed on non-reflective silicon sample holders (diameter = 14 mm). To maintain the internal atmosphere, the samples were covered with airtight caps. To investigate the ammonia uptake behavior of _EAPbI3 , a filter paper moistened with NH3(aq) was placed in the sample holder and measurements were performed under saturated conditions. The simulated XRD patterns of _PbI2 , EAI, and Pb(OH)I were calculated from ICSD68819, CCDC1318979, and ICSD192169, respectively.

Single crystal XRD data were measured at 300 K using Mo Kα (λ = 0.71073 Å) radiation using an AFC-8 diffractometer equipped with a Saturn70 charge-coupled device detector (Rigaku Corporation). All structures were solved by the dual-space method in the SHELXT-2018/2 program and corrected by the full-matrix least-squares method in the SHELXL-2018/3 program.

The crystal structures were drawn using VESTA, and supplementary crystallographic data for _EAPbI3 and Pb(OH)I are contained in CCDC 2077393 and CSD 2077394, which are available from the Cambridge Crystallographic Data Centre (www.ccdc.cam.ac.uk/data_request/cif).

(Reagents and other materials)
Unless otherwise stated, compounds and solvents were purchased commercially and used without further purification. Anhydrous DMF, ethylamine solution (70% in water), hydroiodic acid (HI) (57% in water), ammonium iodide (NH ₄ I), chloroform (CHCl ₃ ), and diethyl ether were purchased from Fujifilm Wako Pure Chemical Industries, Ltd. (Osaka, Japan). Lead(II) iodide (PbI ₂ ) (99.99% purity), methylammonium iodide (>98% purity), and γ-butyrolactone (GBL) were purchased from Tokyo Chemical Industry Co., Ltd. (Tokyo, Japan). Ammonia solution (NH ₃ (aq), 28% in water) was purchased from Junsei Chemical Co., Ltd. (Tokyo, Japan). Deuterated dimethyl sulfoxide (DMSO-d ₆ ) was purchased from Sigma-Aldrich Co., Ltd. (St. Louis, MO, USA). Syringe filters (GLCTD-PTFE1345, pore size = 0.45 μm) were purchased from Shimadzu Corporation (Kyoto, Japan). Filter paper (No. 6, diameter 21 mm, thickness 0.19 mm) was purchased from Kiriyama Seisakusho Co., Ltd. (Tokyo, Japan). Silicon substrates (15 mm × 15 mm, thickness = 0.5 mm, (100) orientation, n-type resistance < 0.02 Ω cm) were purchased from Nilaco Corporation (Tokyo, Japan). Elastic carbon-coated copper grids (ELS-C10) were purchased from Oken Shoji Co., Ltd. (Tokyo, Japan).

(Synthesis)
Ethylammonium iodide (EAI): HI (2.5 mL, 18.9 mmol) was added dropwise to 70% ethylamine (2.5 mL, 26.4 mmol) at 0° C. After stirring for 2 h, the resulting solution was evaporated under reduced pressure at 60° C. The crude product was purified by washing with diethyl ether. The solid was dried under vacuum at 25° C. to give EAI as a white solid (3.7 g, 81%). 1H-NMR (400 MHz, DMSO-d ₆ ): δ=1.14 (t, 3H, J=7.2 Hz, CH ₃ CH ₂ NH ₃ I), 2.84 (q, 2H, CH ₃ CH ₂ NH ₃ I, J=7.3 Hz), 7.58 (s, 3H, CH ₃ CH ₂ NH ₃ I). HRMS calculated for _C2H8N ⁺ ([M]+): 46.0651, found: _46.0651 .
Ethylammonium lead iodide ( _EAPbI3 ): _PbI2 (0.60 g, 1.3 mmol) and EAI (0.23 g, 1.3 mmol) were dissolved separately in anhydrous DMF (1 mL), and then the solution was sonicated for 5 min. The EAI solution was added to the _PbI2 solution. After sonication, the mixture became a homogeneous yellow solution. The resulting solution was dried on a glass substrate at 100 °C under nitrogen using a temperature controller (FP90 central processor with FP-82HT hot stage, Mettler Toledo, Columbus, OH, USA). After drying at 70 °C under reduced pressure for 3 h, _EAPbI3 was obtained as a yellow solid (0.83 g, quantitative). 1H-NMR (400 MHz, DMSO- _d6 ): δ = 1.14 (t, 3H, J = _7.2 Hz _{, CH3CH2NH3PbI3} ), 2.83 ( _q , 2H, J = 7.2 Hz, CH3CH2NH3PbI3 ₎ , 7.56 (s, 3H, CH3CH2NH3PbI3 ₎ . ₁₀ % weight loss temperature: 251 ° _C . Calculated for _C2H8I3NPb : C, 3.79; H, 1.27; N, 2.21, found: 3.81 _{; H} , 1.19; N, 2.18.
FIG. 27 is a graph showing the NMR spectrum of CH ₃ CH ₂ NH ₃ I.
FIG. 28 is a graph showing _{the NMR} spectrum of _{CH3CH2NH3PbI3 .}

(Sample preparation)
Single crystal of _EAPbI3 : The detailed conditions for single crystal growth are shown in Table 1. The optimal conditions for single crystal growth are as follows (Entry 9 in Table 1): _PbI2 (0.23 g, 0.5 mmol) and EAI (0.13 g, 0.75 mmol) were dissolved in GBL (1 mL). The solution was sonicated for 5 min, and then the solution was filtered using a syringe filter. The resulting solution was placed in a small vial with a perforated lid. The small vial was then placed in a larger vial containing _CHCl3 (5 mL). The sample was kept at 15 °C on a cooling stage (NDC-100, Nisshin Rika Co., Ltd., Tokyo, Japan). After 72 h, a mixture of hexagonal and needle-like crystals was formed. When the mixture was left at 25 °C for 1 week, only hexagonal crystals were obtained (average size = 0.1 mm × 0.1 mm × 0.07 mm).
Single crystal of Pb(OH)I: A single crystal of _EAPbI3 (7 mg, 0.01 mmol) was placed in a vial. The single crystal was exposed to _NH3 (aq) vapor for 20 h at 25 °C. Needle-like white crystals (average size = 0.5 mm × 0.06 mm × 0.05 mm) were obtained that could be used for X-ray crystallography.
Preparation of _PbI2 crystals from Pb(OH)I: A single crystal of Pb(OH)I (20 mg, 0.06 mmol) was dissolved in HI (57% in water, 34 μL). The homogeneous solution was kept at 0 °C for 10 min. The solution was then heated under vacuum at 50 °C for 2 h to give yellow crystals of _PbI2 (24 mg, 0.05 mmol).
Preparation of EAI crystals from ethylamine: _NH4I (30 mg, 0.21 mmol) was dissolved in ethylamine (70% in water, 0.3 mL). The homogeneous solution was kept at 25° C. for 1 h. The solution was then heated under vacuum at 50° C. for 2 h to give white crystals of EAI (36 mg, 0.21 mmol).

(Characteristics evaluation)
Crystal data of EAPbI ₃ (CCDC 2077393): C ₂ H ₈ I ₃ NPb, M = 633.98, orthorhombic, Pnma, a = 8.16401 (13) Å, b = 8.75265 (15) Å, c = 15.1541 (3) Å, V = 1082.86 (3) Å ³ , T = 300 K, Z = 4, λ = 0.71073 Å, μ (Mo Kα) = 24.061 mm ^-1 , F (000) = 1072, crystal color = yellow, crystal shape = plate, crystal size = 0.112 mm x 0.097 mm x 0.068 mm, 1864 independent reflections (R _int = 0.0299). Diffraction angle range: 2.834° to 31.486°. Final R ₁ =0.0419, I>2σ(I) and wR ₂ =0.1050 for all data. Goodness of fit with F ² : 1.178.
Crystal data of Pb(OH)I (CSD 2077394): HIOPb, M=351.10, orthorhombic, Pnma, a=7.8332(3) Å, b=4.2187(4) Å, c=10.48750(17) Å, V=346.57(4) Å ³ , T = 300K, Z = 4, λ = 0.71073 Å, μ (Mo Kα) = 57.320 mm ^-1 , F (000) = 576, crystal color = colorless, crystal shape = acicular, crystal size = 0.472 mm x 0.062 mm x 0.046 mm, 450 independent reflections (R _int =0.1576). Diffraction angle range: 3.246° to 27.479°. Final R ₁ =0.0374, I>2σ(I) and wR ₂ =0.0901 for all data. Goodness of fit with F ₂ : 1.188.

(In Table 1, EAI stands for ethylammonium iodide, and GBL stands for gamma-butyrolactone.)

(Optical properties)
The _EAPbI3 soaked in paper was placed in a sample holder (PSH-002, JASCO Corporation, Tokyo, Japan). The sample was sealed with a screw cap to avoid evaporation of _NH3 . Reflectance spectra were measured using a UV-visible spectrophotometer (V-550, JASCO) equipped with an integrating sphere attachment (ISV-469, JASCO).
The diffuse reflectance spectra of the samples were obtained from the Kubelka-Munk function.
The fluorescence spectrum of the sample was measured using a spectrofluorophotometer (FP-6500, JASCO) equipped with a sample holder attachment (FPA-810, JASCO). The incident angle of the excitation light was set to 30°.

(Energy Band Gap)
The energy band gap (Eg) was determined from the Tauc plots according to the equation αhν=(hν−Eg)1/2, where α is the absorption coefficient and hν is the photon energy. Software (Spectra Manager II, JASCO) was used to analyze the Eg values.

(Detection limit, response time, and chemical selectivity)
The _EAPbI3 soaked on the paper was placed in a vial. The sample was placed in a glove box under nitrogen atmosphere. The initial condition was performed after replacing the inside of the glove box with nitrogen for 20 minutes. After _NH3 (feed rate: 15 mL/min) was fed into the glove box, the concentration was checked using an _NH3 gas detector (AR8500, Smart Sensor Ltd., Dongguan, China). The distance between the sample and the detector was 8 cm. After exposure to a predetermined concentration of _NH3 , the sample was stored in a sample holder in the glove box. To avoid evaporation of _NH3 , the sample holder was sealed with a screw cap. The detection limit and response time of _NH3 were evaluated using a spectrofluorometer (FP-6500, JASCO).
To check the chemical selectivity, adsorption samples of _NH3 (aq), pyridine, triethylamine, and 4-fluoroaniline were prepared as follows: _EAPbI3 on paper was placed in a small vial. This small vial was placed in a larger vial containing cotton on which nitrogen compounds were adsorbed. After the vial was capped, the sample was kept in saturated steam at 25 °C for 24 h.

[Synthesis and structural analysis of _EAPbI3 ]
As an ammonia storage compound, _EAPbI3 was synthesized from a precursor solution of ethylammonium iodide (EAI) and lead iodide ( _PbI2 ) in N,N-dimethylformamide (DMF) with a molar ratio of 1:1 using the aforementioned reagents. The solution was dropped onto a glass substrate and dried at 100 °C under nitrogen. The resulting solid was placed in an agate mortar and ground with an agate pestle. The powder was then dried under vacuum at 70 °C for 3 h to obtain the dried _EAPbI3 sample.

Figure 1 shows the appearance of the synthesized EAPbI ₃ and a photograph of the ammonia uptake test. (a) shows an SEM image and the appearance (upper left) of the synthesized EAPbI _3. (b) is a photograph showing the experimental setup for investigating the uptake behavior of NH ₃ (aq) vapor by EAPbI _3. (i) in (b) shows the sample before NH ₃ exposure, and (ii) shows the sample after NH ₃ exposure at 25°C for 10 minutes.

As shown in (a) of the figure, _EAPbI3 exhibited a smooth surface without any amorphous or porous structure by scanning electron microscopy (SEM).

The structural change of _EAPbI3 was then investigated by exposure to _NH3 (aq) vapor. As shown in (b)(i), _EAPbI3 was placed in a small vial, which was then placed in a larger vial containing cotton with _NH3 (aq) adsorbed on it. After the vial was capped, the sample was kept in saturated _NH3 (aq) vapor.
As shown in (b)(ii), the yellow color of _EAPbI3 changed to white after 10 min of exposure, after which no further color change was observed if the lid was kept closed.
Single crystal X-ray diffraction (XRD) analysis indicated that the structural transformation occurred via a cation/anion exchange reaction.
Figure 2 is a schematic diagram of the crystal structures of _EAPbI3 and Pb(OH)I, where (i) _{shows EAPbI3} and (ii) shows Pb(OH)I.

3 is a photograph of _EAPbI3 and Pb(OH)I observed by an optical microscope, (i) shows _EAPbI3 , and (ii) shows Pb(OH)I.
Figure 4 is a schematic diagram showing the arrangement of _EAPbI3 crystals, where (i) shows the view from the a-axis in Figure 2(i), (ii) shows the view from the b-axis, and (iii) shows the view from the c-axis.
5 is another schematic diagram showing the arrangement of Pb(OH)I crystals, where (i) shows the view from the a-axis in FIG. 2(ii), (ii) shows the view from the b-axis, and (iii) shows the view from the c-axis.
Hexagonal EAPbI3 _single crystals had been prepared by vapor diffusion, as shown in Fig. 3(a). _EAPbI3 showed molecular packing of _CH3CH2NH3 ⁺ _cations between 1D columnar structures of [ _PbI6 ] ^4- _octahedra along the a-axis shown in Fig. 2(i) (Fig. 4). The hexagonal EAPbI3 _single crystals changed into needle-like single crystals after exposure to _NH3 (aq) vapor, as shown in the above photograph. The obtained single crystals were Pb(OH)I with ^OH- anions (Fig. 3(ii)). This white crystal had a two-dimensional layered structure with [ _PbI3 ] ^-ions perpendicular to the a-axis. Furthermore, [ _OHPb3 ] tetrahedra stabilized the 2D layered structure with an interlayer distance of 4.18 Å (Fig. 5).

[Verification of _NH3 storage capacity of _EAPbI3 ]
Furthermore, the inventors found that the structural transformation of _EAPbI3 can be applied to the storage of _NH3 .
6 is a graph showing the adsorption isotherm and TG-MS results of EAPbI3. (a) shows the adsorption isotherm of _NH3 uptake by _EAPbI3 at 25°C. (b) shows the thermogravimetric mass spectrometry (TG-MS) results for _NH3 extraction _{by EAPbI3} (heating rate = 5°C/min).
As shown in (a), the adsorption isotherm showed a total _NH3 uptake of 10.2 mmol/g at 1 bar and 25 °C. This uptake behavior did not occur until 80 mbar, indicating the existence of a threshold for _NH3 uptake. The _NH3 extraction behavior was also investigated by TG-MS analysis, and as the weight of the sample started to decrease from 40 °C, m/z = 17 for [ _NH3 ] ⁺ and m/z = 18 for [ _H2O ] ⁺ were observed, which correspond to the extraction of _NH3 (aq) vapor, as shown in (b). The _NH3 extraction reached a maximum at 90 °C and decreased at higher temperatures.

Furthermore, through detailed investigation, the inventors found that _NH3 could be completely extracted by keeping the sample in vacuum at 50°C for 3 hours.
FIG. 7 is a photograph of the sample of this embodiment taken during X-ray analysis.
As shown in the figure, the samples were covered with an airtight cap to continue to maintain the same atmosphere.

8 is a graph showing the change in the XRD pattern of _EAPbI3 , (i) _EAPbI3 before treatment, (ii) after _NH3 (aq) incorporation, and (iii) after _NH3 extraction under vacuum at 50° C. Unless otherwise stated, measurements were performed at room temperature.
FIG. 9 is a graph showing the X-ray diffraction pattern of _EAPbI3 .
FIG. 10 is a schematic diagram showing the spacings of d001 and d002 in a crystal structure.

XRD showed a reversible structural change upon _NH3 incorporation/extraction, as shown in Fig. 8. Before _NH3 incorporation, _EAPbI3 exhibited an orthorhombic crystal system with the space group of Pnma (i).
As shown in Figures 9 and 10, the 1D chains consisting of face-sharing octahedral units of [ _PbI6 ] ^4- were stretched along the a-axis. The 1D columns were aligned in the [011] and [010] directions with spacings of 8.82 Å and 8.75 Å, respectively. Furthermore, the XRD of _EAPbI3 showed strong peaks at 2θ = 11.7° corresponding to the 011 and 002 reflections. The planar spacings d011 and d002 were consistent with the planes along which the 1D columns were aligned. The XRD pattern changed significantly after incorporation of _NH3 (aq) vapor, showing the Pb(OH)I XRD pattern (Figure 8(ii)).
After extraction with _NH3 (aq) under vacuum at 50 °C for 3 h, the XRD pattern reverted to that of _EAPbI3 . The change in peak position was less than 0.13% in 2θ (Figure 8(iii)).

FIG. 11 is a photographic representation showing repeated _NH3 uptake/extraction of _EAPbI3 .
As shown in the figure, when the chemical structure is changed repeatedly, the same color change (yellowing, whitening) is observed. That is, when _NH3 is taken up, it becomes white (light color) in the first (ii) and second (iv) times, and when _NH3 is extracted, it turns yellow again and almost returns to the color before _NH3 is taken up. In other words, the reversible property of being able to repeat the structural change was revealed.

FIG. 12 is a graph showing XRD patterns of _EAPbI3 in the states (i), (iii), and (v) in FIG.
As can be seen, the shift of the peak at 2θ=11.7° is less than 0.06°, indicating that the 1D columnar structure is almost unchanged between states (i) and (v).

FIG. 13 is a schematic diagram showing a putative mechanism of _NH3 storage proposed to explain the reversible structural change upon _NH3 uptake/extraction.

It was then shown that the forward reaction after uptake of NH ₃ (aq) vapor (NH _{3 +} H ₂ O) gave Pb(OH)I by hydrolysis and ethylamine (CH ₃ CH ₂ NH ₂ ) by addition reaction.
14 is a graphical representation showing NMR spectra of EAPbI ₃ before and after NH ₃ incorporation. 1H NMR spectra in deuterated dimethylsulfoxide (DMSO-d ₆ ) show (i) untreated EAPbI ₃ , (ii) after exposure of EAPbI ₃ to NH ₃ (aq) vapor, and (iii) after removal of NH ₃ (aq) (TMS = tetramethylsilane).

The formation of _CH3CH2NH2 was evaluated by 1H NMR spectroscopy. Untreated _EAPbI3 in deuterated _{dimethylsulfoxide} showed chemical shifts of _{ethylammonium} at 7.56 ppm (CH3CH2NH3+), _{2.83 ppm} ( _CH3CH2NH3 ⁺ ₎ , and 1.14 ppm ( _CH3CH2NH3 ⁺ ₎ (i). After uptake of _{NH3 (} aq) vapor, due to excess _NH3 , chemical shifts were present at 2.74 _ppm ( _CH3CH2NH2 ) and 1.08 ppm ( _{CH3CH2NH2 )} (ii). More importantly, the ammonium peak disappeared after uptake of _NH3 , indicating _{that unprotonated CH3CH2NH2 amine} was formed. _NH3 extraction caused a _peak ^{shift and broadening of CH3CH2NH3+} _{, while} again identifying the integral of _EAPbI3 (iii).

Next, XRD measurements were carried out to clarify the reverse reaction.
Fig. 15 is a graph showing the XRD patterns of _PbI2 and EAI. In Fig. 15(a), (i) is the XRD pattern of Pb(OH)I, (ii) is the XRD pattern after reaction with HI, and (iii) is the XRD pattern of _PbI2 . The vertical line under the graph in the figure indicates ICSD 68819. The indices of the reflection peaks are shown in Table 2 below.
According to the figure, Pb(OH)I crystals underwent a condensation reaction with 57% hydroiodic acid (HI), and the change in the XRD pattern after drying at 50 °C was consistent with the XRD pattern of _PbI2 .

The reaction of 70% _{CH3CH2NH2 with ammonium} iodide ( _NH4I ) was also investigated.
In Fig. 15(b), (i) is the _{XRD pattern of NH4I , (ii) is the pattern after the reaction with CH3CH2NH2 , and} (iii) is the XRD pattern of EAI, and the vertical line under the graph in the figure indicates CCDC 1318979. In addition, the indices of the reflection peaks are shown in Table 3 described later.
The XRD pattern of the product dried at 50 °C after the elimination reaction was in good agreement with that of EAI. These experimental results led us to infer that all the compounds are necessary for the reverse reaction of Pb(OH)I to _EAPbI3 .

To elucidate the above phenomenon, a control experiment was carried out.
16 is a graph showing the XRD patterns of Pb(OH)I (i) before washing with water, (ii) after washing, and (iii) after heating sample (ii) at 50° C. for 6 hours. The vertical lines in the figure indicate ICSD 192169.
The water-soluble compounds HI, _{CH3CH2NH2 ,} and _NH4I were removed from Pb(OH)I by washing with water. _The XRD pattern of the washed crystals was the same as that of the Pb(OH)I crystals. Furthermore, the XRD pattern did not change even when the washed crystals were heated at 50°C. These results suggested that the presence of water-soluble compounds was important for the reverse reaction.

(In Table 2, _d1 indicates the lattice spacing of the product obtained by the reaction of Pb(OH)I with HI, and _d2 indicates the lattice spacing of _PbI2 .)

(In Table 3, _d1 represents the lattice spacing of the product obtained by the reaction of ethylamine with NH ₄ I, and _d2 represents the lattice spacing of EAI. [a] represents unknown data.)

Fig. 17 is a schematic diagram showing the action of the ammonia storage compound contained in the ammonia storage composition of this embodiment. As shown in the figure, the ammonia storage compound has a 1D columnar structure when it does not incorporate ammonia (NH ₃ ), and a 2D layered structure when it incorporates ammonia. These mutual changes of structures can be repeated reversibly under certain conditions, so that it can be used to incorporate and extract ammonia. Therefore, the ammonia storage compound of this embodiment can be used to store ammonia.

[Steam discoloration behavior]
The steam discoloration behavior of _EAPbI3 crystals printed on paper was investigated.
Printing on paper with crystals was performed using a stamp. A metal stamp was dipped into an anhydrous N,N-dimethylformamide (DMF) solution of EAPbI ₃ (830 mg/mL) to print the letter R on paper. The sample was dried at 100 °C under vacuum for 3 h. Samples of EAPbI ₃ soaked on paper were also investigated. The paper was dipped into the DMF solution at 25 °C for 60 s. The concentration of EAPbI ₃ in DMF was varied between 19.8 and 634 mg/mL. The wet samples were dried at 100 °C under vacuum for 3 h. After drying, the soaked EAPbI ₃ on paper was cut into rectangles (size: 5 mm × 20 mm). The thickness of the samples was measured using a micrometer (CLM1-15QM with micrometer stand (MS-RB), Mitutoyo Corporation, Kawasaki, Japan).

18 is a photograph showing the steam discoloration behavior of _EAPbI3 crystals stamped on paper in response to _NH3 vapor. (i) Untreated _EAPbI3 , (ii) after exposure to _NH3 (aq), and (iii) after removal of _NH3 (aq). The thickness of the imprinted characters is 7 μm at 50° C. under vacuum.
As shown in the figure, the letter R was stamped onto paper using a solution of _EAPbI3 in DMF as the "ink" (i), and when the sample was exposed to aqueous ammonia ( _NH3 (aq)) vapor, the yellow lettering disappeared (ii), and after removal of _{the NH3} (aq) by treatment at 50 °C for 2 min, the lettering became visible again (iii).

Figure 19 shows a scanning electron microscope (SEM) image of _EAPbI3 crystals layered on paper. These crystals had plate-like structures with a diameter of 1-2 μm and a thickness of about 100 nm.

The optical properties, detection limits, response times, and chemical selectivity of this paper-layered sample of _EAPbI3 crystals were investigated.
20 is a graph showing the change in diffuse reflectance spectrum of _EAPbI3 upon immersion in paper at 25° C. (i) untreated _EAPbI3 , (ii) after exposure to _NH3 (aq) vapor, and (iii) after removal of _NH3 (aq) at 100° C. under vacuum.
21 is a graph showing the Tauc plots of _EAPbI3 (i ₎ untreated, (ii) after exposure to _NH3 (aq) vapor, and (iii) after removal of _NH3 (aq) at 100° C. under vacuum. The energy band gaps (Eg) were (i) 2.39 eV, (ii) 2.96 eV, and (iii) 2.39 eV, respectively.

The diffuse reflectance spectrum of the paper sample showed a reversible change in the energy band gap (Eg) before and after exposure to NH ₃ (aq) vapor. The yellow EAPbI ₃ crystals showed a broad spectrum between 250 and 550 nm. As determined from the Tauc plot, the Eg of this crystal was 2.39 eV. The Eg of the white crystalline Pb(OH)I after exposure to NH ₃ (aq) vapor was 2.96 eV. After removal of NH ₃ (aq), the same initial value of Eg (2.39 eV) was obtained.

22 is a graph showing the fluorescence spectra of _EAPbI3 soaked in paper at 25° C. (i) untreated _EAPbI3 , (ii) after exposure to _NH3 (aq) vapor, and (iii) after removal of _NH3 (aq) under vacuum at 100° C.
_EAPbI3 also showed a reversible change in the fluorescence spectrum: upon optical excitation at 360 nm, a maximum wavelength of 545 nm was observed (i). After exposure to _NH3 (aq) vapor, the fluorescence intensity decreased by 45% (ii). After removal of _NH3 (aq), the intensity returned to the initial value (iii).

FIG. 23 is a graph showing the change in fluorescence spectrum of paper-soaked samples at various concentrations of _NH3 .
Monitoring the fluorescence intensity revealed that _NH3 was detected at a concentration of 10 ppm.

24 is a graph showing the rate of change of fluorescence intensity at 545 nm versus _NH3 concentration. IBefore and IAafter represent the fluorescence intensity at 545 nm before and after exposure to _NH3 , respectively.
A linear relationship was observed between the rate of change of fluorescence intensity at 545 nm and _NH3 concentration with a coefficient of determination R2 = 0.986.

FIG. 25 is a graph showing the change in response time depending on the sample thickness of _EAPbI3 .
The thinner the sample, the faster the response was. For a sample with a thickness of 19 μm, it took 10 min to respond. This slow response was due to the weak penetration of _NH3 into the bulk part of _EAPbI3 . In contrast, for a thickness of 5 μm, the minimum response time was 48 s.

Figure 26 is a photograph showing the adsorption behavior of various solutions onto soaked _EAPbI3 crystals on paper: (a) _NH3 (aq), (b) pyridine, (c) triethylamine, and (d) 4-fluoroaniline, (i) before exposure and (ii) after 24 h exposure at 25 °C.
The chemoselectivity of the steam discoloration behavior was carried out using nitrogen-containing compounds: no color change of _EAPbI3 crystals occurred even after 24 h of exposure to the aromatic compound pyridine, the aliphatic compound triethylamine, and the amine-substituted compound 4-fluoroaniline.

The ammonia storage compound of this embodiment selectively responds to ammonia water and ammonia vapor on a thin film such as paper and changes color, so it may be applicable to sensors and test papers that indicate the amount of ammonia stored by the color.

[Vapor discoloration behavior: additional compounds]
Figure 30 is a photograph showing the adsorption behavior of various solutions on the crystals of other compounds. The adsorption behavior of NH ₃ (aq) was examined for each compound shown in the figure, EAPbBr ₃ , FEAPbI ₃ , HOEAPbI ₃ , PbI ₂ , (PEA) ₂ PbI ₄ , (BA) ₂ (MA) Pb ₂ I ₇ , (BA) ₂ (MA) ₂ Pb 3 I ₁₀ , (BA _{) 2} (MA) ₃ Pb ₄ I ₁₃ , and (BA) ₂ (MA) ₄ Pb ₅ I ₁₆ , using the same method as in Figure 26 except that it was performed directly on the crystals.

Chemical synthesis of EAPbBr ₃ , FEAPbI ₃ , and HOEAPbI ₃ was outsourced to i Chemical Lab Co., Ltd. In summary, the synthesis was carried out as follows.

(Synthesis of _EAPbBr3 )
Under an argon atmosphere, EABr (7.67 g, 60.9 mmol, 1.00 eq) was added to dehydrated DMF (45 ml) and dissolved by ultrasonic treatment. Separately, under an argon atmosphere, lead bromide (22.3 g, 60.8 mmol, 1.00 eq) was added to dehydrated DMF (45 ml) and ultrasonically treated for 5 minutes, and then a separately dissolved EABr/DMF solution was added. After ultrasonic treatment, the mixture was dried under reduced pressure at 70° C. for 5 hours and dried under reduced pressure at 80° C. for 7.5 hours to obtain 29.6 g (60.1 mmol) of a yellow solid as EAPbBr ₃ .

(Synthesis of _FEAPbI3 )
Under an argon atmosphere, FEA (4.94 g, 48.3 mmol, 1.03 eq) was ice-cooled and stirred. 57% hydroiodic acid (10.8 g, 48.3 mmol, 1.03 eq) was added dropwise thereto over 4 minutes. After stirring for 2 hours while ice-cooled, the solvent was distilled off under reduced pressure at 50°C. 11.7 g of a yellow solid was obtained as a crude product. The crude product was suspended and stirred in diethyl ether (60 ml), and after 30 minutes, the solid was suction filtered and washed with diethyl ether. 6.80 g (30 mmol) of a white solid was obtained as FEAI. Under an argon atmosphere, FEAI (11.8 g, 51.9 mmol, 1.00 eq) was placed in dehydrated DMF (40 ml) and dissolved by ultrasonic treatment. In an argon atmosphere, lead iodide (23.9 g, 51.9 mmol, 1.00 eq) was added to dehydrated DMF (40 ml) and subjected to ultrasonic treatment for 5 minutes.
The mixture was treated with ultrasonic waves and then dried under reduced pressure at 70° C. for 7 hours. The mixture was then ground in a mortar and dried under reduced pressure at 80° C. for 3 hours to obtain 36.9 g (53.6 mmol) of a yellow solid as _FEAPbI3 .

(Synthesis of _HOEAPbI3 )
Under an argon atmosphere, HOEAI (8.29 g, 43.8 mmol, 1.00 eq) was added to dehydrated DMF (34 ml) and dissolved by ultrasonic treatment. Separately, under an argon atmosphere, lead iodide (20.2 g, 43.8 mmol, 1.00 eq) was added to dehydrated DMF (34 ml) and ultrasonicated for 5 minutes, and then a separately dissolved HOEAI/DMF solution was added. After ultrasonic treatment, the mixture was dried under reduced pressure at 70° C. for 5 hours and dried under reduced pressure at 80° C. for 4 hours to obtain 28.2 g (43.3 mmol) of yellow solid as HOEAPbI ₃ .

_PbI2 (L0279) was _purchased from Tokyo Chemical Industry Co., Ltd., (PEA) _2PbI4 ( ₉₁₀₉₃₇ ), (BA) ₂ (MA)Pb2I7 ( _{912816), (BA)2(MA)2Pb3I10 (912557), (BA)2 ( MA )3Pb4I13 (914363), and (BA)2 ( MA ) 4Pb5I16 ( 912301 ) were} purchased from Aldrich. The numbers in parentheses after the compound names indicate catalog numbers _.

In the figures, (i) is before exposure and (ii) is after 20 hours exposure at 25° C. The chemoselectivity of the steam discoloration behavior was carried out using nitrogen-containing compounds.
Crystals of both compounds turned white (light colored) when exposed to _NH3 , indicating that adsorption occurred.

[Adsorption isotherm: additional compound]
Adsorption isotherms were measured for each of the compounds in the same manner as in Fig. 6. The measurements were performed at room temperature (25°C).
31, 32 and 33 are graphs showing adsorption isotherms for further compounds.
FIG. 31(a) shows the adsorption isotherm of EAPbI ₃ , (b) shows the adsorption isotherm of EAPbBr ₃ , (c) shows the adsorption isotherm of FEAPbI ₃ , and (d) shows the adsorption isotherm of HOEAPbI ₃ .
FIG. 32(a) shows the adsorption isotherms of GuaPbI ₃ , (b) shows the adsorption isotherms of PbI ₂ , (c) shows the adsorption isotherms of (BA) ₂ PbI ₄ , and (d) shows the adsorption isotherms of (PEA) ₂ PbI ₄ .
FIG _{. 33(a) is (BA)2(MA)2Pb2I7 , (b) is (BA)2(MA)2Pb3I10 , and ( c} ) is ( _BA ) ₂ (MA) _{3Pb4 .} I ₁₃ , (d) shows the adsorption isotherm of (BA) ₂ (MA) ₄ Pb ₅ I ₁₆ .
The uptake behavior of these compounds was such that no adsorption occurred at around 200 mbar, and the adsorption capacity gradually increased, or the adsorption capacity increased significantly at 800 to 1000 mbar (1 bar).

[Ammonia storage capacity: additional compounds]
From the adsorption isotherms, the ammonia storage capacity (mmol/g) at room temperature and normal pressure (25° C., 1 bar) of each compound is shown in Table 4.

All of the above compounds achieved an ammonia storage capacity of 6.6 or more, with even better ones achieving 9 or more, and particularly good ones achieving 10 or more, demonstrating effective performance.

[Measurement of ammonia removal behavior: additional compounds]
The ammonia removal behavior of each of the above compounds was measured using TG-MS.
Using the same method as in FIG. 6, thermogravimetric mass spectrometry (TG-MS) was performed on each compound for _NH3 extraction (heating rate = 5°C/min).
34, 35 and 36 are graphs showing the results of thermogravimetric mass spectrometry for further compounds.
FIG. 34(a) shows the thermogravimetric and mass spectrometry results of EAPbI ₃ , (b) EAPbBr ₃ , (c) FEAPbI ₃ , and (d) HOEAPbI ₃ .
FIG. 35(a) shows the thermogravimetric and mass spectrometry results of GuaPbI ₃ , (b) shows the thermogravimetric and mass spectrometry results of PbI ₂ , (c) shows the thermogravimetric and mass spectrometry results of (BA) ₂ PbI ₄ , and (d) shows the thermogravimetric and mass spectrometry results of (PEA) ₂ PbI ₄ .
Figure 36 ( _a ) shows the _{thermogravimetric and mass} analyses of (BA _{) 2} ( _MA ) _2Pb2I7 , (b) ( _{BA ) 2} (MA) _2Pb3I10 , (c) (BA) ₂ (MA) _3Pb4I13 , and ( _d ) (BA) ₂ (MA) _4Pb5I16 .
As shown in the figure, it was clear that the ammonia adsorbed in each compound could be removed by heating, and that each compound showed a peak in the vicinity of 60-90°C.

Next, a test was conducted to confirm the maintenance of storage capacity when ammonia storage cycles were repeated. The repeated cycles were confirmed as follows.
The open container containing the compound (crystal) and cotton soaked in ammonia water were placed in a sealed container and left to stand at 25° C. for 20 hours. After that, the open container containing the compound was taken out and negative pressure was applied on a hot plate at 50° C. for 3 hours. This operation was counted as one cycle, and 15 cycles were performed.
Table 5 shows the initial and post-15 cycle ammonia storage capacities for each compound.

For all compounds, a constant ammonia storage capacity was maintained before and after 15 cycles of ammonia storage and release. In particular, no decrease in storage capacity was observed for EAPBI ₃ , FEAPBI ₃ , and (BA) ₂ (MA) ₂ PB ₃ I ₁₀ .

Although the embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. These embodiments and their modifications are within the scope of the invention and its equivalents set forth in the claims, as well as the scope and gist of the invention.

The present invention provides an ammonia storage composition that allows ammonia to be stored relatively easily under mild conditions and with a high degree of safety, an ammonia storage device that uses the composition, an ammonia storage method, and a method for removing ammonia molecules.

Reference Signs List 1 Ammonia storage composition 2 Ammonia binding composition 11 First holding member 12 Bonding treatment member 21 Second holding member 22 Release treatment member 100 Ammonia storage device

Claims (12)

Any of the following formulas (I-a) to (I-c):
PbI ₂ ... (I-a)
RPbX ₃ ... (I-b)
R _n+1 Pb _n X _3n+1 ... (I-c)
(In the formula (I-b) and the formula (1-c), R represents ammonium, guanidinium or formamidinium containing a hydrocarbon group having 1 to 10 carbon atoms which may be substituted, X represents a halogen element, and when the formula contains two or more Rs, they may be the same or different, and n represents a natural number), comprising at least one ammonia storage compound represented by the formula (I-b) and the formula (1-c). The ammonia storage compound is
R ₁ NH ₃ PbI ₃ ... (I-d)
(In the formula (I-d), R ₁ is a hydrocarbon group having 1 to 10 carbon atoms which may be substituted.)
2. The ammonia storage composition according to claim 1, An ammonia-binding composition comprising the ammonia storage composition according to claim 1 and an ammonia-binding compound in which an ammonia molecule and a water molecule are further bound to the ammonia storage compound. 13. An ammonia storage device comprising the ammonia storage composition of claim 1,
A first retention member for retaining the ammonia storage composition;
The ammonia storage composition held in the first holding member is contacted with ammonia molecules and water under conditions of an ammonia binding pressure P1 and an ammonia binding temperature T1,
The ammonia storage device further comprises a means for further binding ammonia molecules and water molecules to the at least one ammonia storage compound to obtain an ammonia-binding composition. a second retention member for retaining the ammonia-binding composition;
The ammonia-binding composition held in the second holding member is treated under conditions of an ammonia desorption pressure P2 and an ammonia desorption temperature T2 to desorb ammonia molecules from the ammonia-binding composition to obtain at least one ammonia storage compound;
5. The ammonia storage device of claim 4, further comprising means for collecting ammonia molecules disengaged from the ammonia-binding composition. the ammonia binding temperature T1 and the ammonia desorption temperature T2 have a relationship of T2>T1,
The ammonia binding pressure P1 and the ammonia desorption pressure P2 have a relationship of P2<P1.
6. The ammonia storage device of claim 5. 1. A method for storing ammonia, comprising:
Any of the following formulas (I-a) to (I-c):
PbI ₂ ... (I-a)
RPbX ₃ ... (I-b)
R _n+1 Pb _n X _3n+1 ... (I-c)
(In the formula (I-b) and formula (1-c), R represents an ammonium, guanidinium or formamidinium containing a hydrocarbon group having 1 to 10 carbon atoms which may be substituted, X represents a halogen element, and when the formula contains two or more Rs, they may be the same or different, and n represents a natural number.)
For at least one ammonia storage compound represented by
An ammonia storage method comprising: an ammonia storage step of contacting ammonia molecules with water under conditions of an ammonia binding pressure P1 and an ammonia binding temperature T1 to cause a chemical reaction. The ammonia storage compound is
R ₁ NH ₃ PbI ₃ ... (I-d)
(In the formula (I-d), R ₁ is a hydrocarbon group having 1 to 10 carbon atoms which may be substituted.)
The method for storing ammonia according to claim 7, The method for storing ammonia according to claim 7, further comprising an ammonia desorption step of treating the ammonia-bound composition under conditions of an ammonia desorption pressure P2 and an ammonia desorption temperature T2 to liberate ammonia molecules from the ammonia-bound composition. the ammonia binding temperature T1 and the ammonia desorption temperature T2 have a relationship of T2>T1,
The ammonia binding pressure P1 and the ammonia desorption pressure P2 have a relationship of P2<P1.
The method for storing ammonia according to claim 9. Any of the following formulas (I-a) to (I-c):
PbI ₂ ... (I-a)
RPbX ₃ ... (I-b)
R _n+1 Pb _n X _3n+1 ... (I-c)
(In the formula (I-b) and formula (1-c), R represents an ammonium, guanidinium or formamidinium containing a hydrocarbon group having 1 to 10 carbon atoms which may be substituted, X represents a halogen element, and when the formula contains two or more Rs, they may be the same or different, and n represents a natural number.)
A method for removing ammonia molecules, comprising: contacting an ammonia storage composition containing at least one ammonia storage compound represented by the formula (I) with a gas phase containing at least ammonia molecules and water molecules, thereby chemically reacting at least a portion of the ammonia molecules and water molecules in the gas phase with the ammonia storage compound. The ammonia storage compound is
R ₁ NH ₃ PbI ₃ ... (I-d)
(In the formula (I-d), R ₁ is a hydrocarbon group having 1 to 10 carbon atoms which may be substituted.)
The method for removing ammonia molecules according to claim 11,

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