JP6982295B2 - Ammonia gas indicator - Google Patents

Description

The present invention relates to an ammonia gas indicator for visually confirming ammonia gas in the atmosphere or the like.

Ammonia (NH ₃ ) is the chemical substance with the highest production volume, and most of it is used as a raw material for basic chemicals such as nitric acid and nitrogen fertilizer such as sulfur cheap. It is being considered to be used directly or indirectly as an energy source. Directly, thermal energy is extracted by directly burning ammonia gas, and indirectly, hydrogen is generated by decomposing ammonia, and hydrogen is converted into electrical energy by using it in a fuel cell (non-). Patent Document 1).

On the other hand, in terms of the environment, ammonia is a colorless gas at normal temperature and pressure, and is a substance with a peculiar strong pungent odor. The concentration of ammonia generated by the metabolism of living organisms is several hundred ppm or more in a closed space. Has been reported. The Japanese Society of Health requires that the ammonia concentration in the working environment be 25 ppmv (parts per million by volume) or less (Non-Patent Document 2).
However, since ammonia gas cannot be visually confirmed, in a work environment where sensors are not always available, it is perceived that the environment contains high-concentration ammonia gas only after inhaling gas exceeding the standard concentration. Will be done.

In addition, ammonia and amines are substances generated when foods, especially meat and fish containing a large amount of protein, are spoiled, and are known to be indicators for food deterioration evaluation.

Further, other than energy applications, ammonia is used as a refrigerant in semiconductor manufacturing and heat pumps. In these industrial applications, 100% ammonia gas of 1 atm or more is mainly used, so it is indispensable to take measures against leakage of ammonia gas.
Monitoring of the spatial ammonia concentration is effective as a measure against leakage, but it is difficult to identify the leakage location even if it is possible to confirm the presence or absence of gas leakage due to the increase in ammonia concentration.

In this way, in order to instantly confirm the concentration range of ammonia gas in the environment such as the work environment and food storage environment, and to confirm the leakage of ammonia gas used in various processes, the ammonia gas indicator that can be visually confirmed is used. In particular, in order to control the ammonia concentration, it is necessary to use one that changes color only when the ammonia gas concentration is above the threshold value and does not change when it is below the threshold value. preferable. By arranging ammonia indicators with different thresholds, it is possible to visually confirm the ammonia concentration range in the measurement environment. Needless to say, it is desirable that the ammonia indicator has selectivity for ammonia gas molecules.

Conventionally, various organic acids whose structural changes change depending on the proton concentration have been used as sensors for visually confirming the ammonia concentration. Organic acids that have protons inside can adsorb dilute ammonia in the atmosphere by reacting with the protons inside.
However, in this reaction, the color changes depending on the amount of adsorbed ammonia regardless of the concentration of ammonia gas in the gas. Therefore, the method using an organic acid does not have an ammonia concentration threshold value and is difficult to use as an index of ammonia gas concentration.

Further, as an indicator for confirming the ammonia gas concentration, a sensor array in which a plurality of organic acids are listed has been reported (Non-Patent Document 2). In this method, the gas concentration is calculated from the color change of each molecule using 20 or more kinds of organic molecules, but it is difficult to visually discriminate, and a spectrometer or the like is required to calculate the concentration.

On the other hand, it is known that a metal cyano complex adsorbs ammonia in its internal structural defects, and some of the metal cyano complexes change the optical spectrum of the cyan complex with the adsorption of ammonia gas. It is known (Patent Document 1).
However, although the document states that the change in the optical spectrum can be used for the ammonia sensor, the presence or absence of the change in the optical spectrum is evaluated in a pure ammonia gas environment of 1 atm. Not only has it not been evaluated for changes at low concentrations, but its use as an ammonia gas indicator has not been investigated. Further, no study has been made on a threshold value of the ammonia concentration at which a visible color change occurs as an indicator, or a method of obtaining a different threshold value by changing the density range at which the color change occurs.

International Publication No. 2015/186819

Japan Society for Occupational Health "Recommendations for Allowable Concentrations 2015", Journal of Japan Society for Occupational Health, 57 (2015), p. 146 M.K. Morsy et al. Food Control 60 (2016) 346-352

As described above, there is a demand for a technique that can instantly and visually confirm the leakage of ammonia gas used in various processes, or the concentration of ammonia in an environment such as a working environment or a food storage environment.
The present invention has been made in view of this situation, and is a material that causes a visible color change when in contact with a medium containing ammonia gas, preferably under an ammonia gas concentration equal to or higher than a threshold value. To provide an ammonia gas indicator that can visually confirm the leakage of ammonia gas from pipes, etc., or the concentration range of ammonia gas in an environment such as a work environment or food storage environment, using a material that changes color. It is the purpose.

In Patent Document 1 , in the metal cyano complex represented by the general formula A _x M [M'(CN) ₆ ] _y · zH ₂ O, when y is small, that is, [M'(CN) ₆ ] in the crystal. When the amount of metal M is small, the metal M is _{abundantly present as compared with [M'(CN) 6} ], and the structure is such that the ligand around the metal M is easily adsorbed. It is assumed that the value of (1-y) indicating the defect rate of _{6 ] and the adsorption amount of NH 3} have a linear relationship.
Therefore, the present inventor examined the use of the metal cyano complex as an indicator of ammonia gas, and found that even if ammonia gas was adsorbed, no visible color change occurred in the metal cyano complex. It turned out that some indicators could not be used.

As a result of further studies, the visible color change in the metal cyano complex does not have a linear relationship with the value of (1-y), and only by adjusting the value of (1-y), It has been found that the metal cyano complex can be used as an ammonia gas indicator.
In addition, the present inventor synthesizes various compositions of the metal cyano complex by various methods and appropriately conducts a test as an ammonia gas gas indicator, whereby the ammonia concentration is determined in the metal cyano complex. It was found that the color changes only when it is above the value and does not change when it is below the threshold value, and by changing at least one of x, y and z in the composition formula, the color changes. It was found that the threshold value of the ammonia gas concentration at which the change occurs or the color of the color change at the threshold value can be changed.

The present invention has been completed based on these findings, and according to the present invention, the following inventions are provided.
[1] The main composition is the general formula A _x M [M'(CN) ₆ ] _y · zH ₂ O
[In the formula, M is a group consisting of vanadium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, copper, silver, zinc, lantern, europium, gadolinium, lutetium, barium, strontium, and calcium. Represents one or more metal atoms selected from, where M'is one or two selected from the group consisting of vanadium, chromium, molybdenum, tungsten, manganese, iron, ruthenium, cobalt, nickel, platinum, and copper. Representing the above metal atoms, A represents one or more cations selected from the group consisting of hydrogen, lithium, sodium, potassium, ruthenium, and lutetium, x is 0 to 3, y is 0.1 to 0.1. 1.0 and z represent numerical values from 0 to 6. ]
A method of using the metal cyano complex shown in (1) as an ammonia gas indicator that causes a visible color change when brought into contact with a medium containing ammonia gas.
[M'in the general formula, which is assumed from the concentration ratio (1 / y) of M and M'at the time of manufacturing the metal cyano complex so as to have a threshold value of the ammonia gas concentration that causes the color change. (CN) _6] wherein supposed defect rate temper pollock Rukoto (1-y) of the.
[2] The method according to [1], wherein the ammonia gas concentration is determined using a plurality of metal cyano complexes having different threshold values of the ammonia gas concentration.
[3] In the above general formula, a metal cyano complex in which M and M'are cobalt, A is potassium, and the assumed defect rate (1-y) is 0.30 or more is used [1] or [2]. ] The method described in.
[4] In the above general formula, a metal cyano complex in which M is cobalt, M'is iron, A is cesium, and the assumed defect rate (1-y) is 0.10 or more is used [1]. ] Or the method according to [2].
[5] In the general formula, a metal cyano complex in which M is iron, M'is cobalt, A is potassium, and the assumed defect rate (1-y) is 1/3 or more is used [1]. ] Or the method according to [2].
[6] The main composition is a general formula
A _x M [M'(CN) ₆ ] _y ・ zH ₂ O
[In the formula, M is a group consisting of vanadium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, copper, silver, zinc, lantern, europium, gadolinium, lutetium, barium, strontium, and calcium. Represents one or more metal atoms selected from, where M'is one or two selected from the group consisting of vanadium, chromium, molybdenum, tungsten, manganese, iron, ruthenium, cobalt, nickel, platinum, and copper. Representing the above metal atoms, A represents one or more cations selected from the group consisting of hydrogen, lithium, sodium, potassium, ruthenium, and lutetium, x is 0 to 3, y is 0.1 to 0.1. 1.0 and z represent numerical values from 0 to 6. ]
An ammonia gas indicator that contains the metal cyano complex shown in (1) as an active ingredient and shows a visible color change when brought into contact with a medium containing ammonia gas.
In the general formula, M and M'are cobalt, A is potassium, and it is assumed from the concentration ratio (1 / y) of M and M'at the time of producing the metal cyano complex, in the general formula. Ammonia gas indicator with an assumed defect rate (1-y) of [M'(CN) _{6] of 0.30 or more.}
[7] The main composition is a general formula
A _x M [M'(CN) ₆ ] _y ・ zH ₂ O
[In the formula, M is a group consisting of vanadium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, copper, silver, zinc, lantern, europium, gadolinium, lutetium, barium, strontium, and calcium. Represents one or more metal atoms selected from, where M'is one or two selected from the group consisting of vanadium, chromium, molybdenum, tungsten, manganese, iron, ruthenium, cobalt, nickel, platinum, and copper. Representing the above metal atoms, A represents one or more cations selected from the group consisting of hydrogen, lithium, sodium, potassium, ruthenium, and lutetium, x is 0 to 3, y is 0.1 to 0.1. 1.0 and z represent numerical values from 0 to 6. ]
An ammonia gas indicator that contains the metal cyano complex shown in (1) as an active ingredient and shows a visible color change when brought into contact with a medium containing ammonia gas.
In the above general formula, M is cobalt, M'is iron, and A is cesium, which is assumed from the concentration ratio (1 / y) of M and M'at the time of producing the metal cyano complex. An ammonia gas indicator in which the assumed defect rate (1-y) of [M'(CN) _{6] in the general formula is 0.10 or more.}
[8] The main composition is a general formula
A _x M [M'(CN) ₆ ] _y ・ zH ₂ O
[In the formula, M is a group consisting of vanadium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, copper, silver, zinc, lantern, europium, gadolinium, lutetium, barium, strontium, and calcium. Represents one or more metal atoms selected from, where M'is one or two selected from the group consisting of vanadium, chromium, molybdenum, tungsten, manganese, iron, ruthenium, cobalt, nickel, platinum, and copper. Representing the above metal atoms, A represents one or more cations selected from the group consisting of hydrogen, lithium, sodium, potassium, ruthenium, and lutetium, x is 0 to 3, y is 0.1 to 0.1. 1.0 and z represent numerical values from 0 to 6. ]
An ammonia gas indicator that contains the metal cyano complex shown in (1) as an active ingredient and shows a visible color change when brought into contact with a medium containing ammonia gas.
In the above general formula, M is iron, M'is cobalt, and A is potassium, which is assumed from the concentration ratio (1 / y) of M and M'at the time of producing the metal cyano complex. Ammonia gas indicator in which the assumed defect rate (1-y) of [M'(CN) _{6] in the general formula is 1/3 or more.}

According to the present invention, it is possible to provide an ammonia indicator capable of visually confirming the leakage of ammonia gas from a pipe or the like used in various processes or the range of ammonia concentration in the environment.

Typical crystal structure of metal cyano complex (1-y) Color change photograph of Co-Co metal cyano complex with different values (1-y) Color change of Co-Co metal cyano complex with different values (RGB display) Adsorption isotherm of Cs-Co-Fecyano complex at 25 ° C Color change of Fe-Cocyano complex upon contact with ammonia

Hereinafter, the present invention will be described in detail.
In the present invention, ammonia (NH ₃ ) refers to ammonia gas unless otherwise specified.

Further, in the present invention, the metal cyano complex has a composition of the general formula A _x M [M'(CN) ₆ ] _y · zH ₂ O.
[In the formula, M is a group consisting of vanadium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, copper, silver, zinc, lantern, europium, gadolinium, lutetium, barium, strontium, and calcium. Represents one or more metal atoms selected from, where M'is one or two selected from the group consisting of vanadium, chromium, molybdenum, tungsten, manganese, iron, ruthenium, cobalt, nickel, platinum, and copper. Representing the above metal atoms, A represents one or more cations selected from the group consisting of hydrogen, lithium, sodium, potassium, ruthenium, and lutetium, x is 0 to 3, y is 0.00 to 0 to 0. 1.0 and z represent numerical values from 0 to 6. ]
When M and M'are identified, it is called an M-M'cyano complex. For example, when M = copper and M'= iron, it is called a copper-iron cyano complex.
Here, the metal atom M is composed of vanadium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, copper, silver, zinc, lanthanum, europium, gadrinium, lutetium, barium, strontium, and calcium. One or more metal atoms selected from the group are preferred, and one or more metal atoms selected from the group consisting of vanadium, chromium, manganese, iron, ruthenium, cobalt, nickel, copper and zinc are more preferred. One or more metal atoms selected from the group consisting of manganese, iron, cobalt, nickel, copper and zinc are particularly preferred. The metal atom M'is preferably one or more metal atoms selected from the group consisting of vanadium, chromium, molybdenum, tungsten, manganese, iron, ruthenium, cobalt, nickel, platinum, and copper, preferably manganese, iron, ruthenium. One or more metal atoms selected from the group consisting of ruthenium and platinum are more preferable, and one or more metal atoms selected from the group consisting of iron and cobalt are more preferable. A is one or more cations selected from the group consisting of hydrogen, lithium, sodium, potassium, rubidium and cesium.

x is preferably 0 to 3, more preferably 0 to 2.5, and particularly preferably 0 to 2. y is preferably 0.1 to 1.0, more preferably 0.4 to 1.0, and particularly preferably 0.5 to 1. z is preferably 0 to 6, more preferably 0.5 to 5.5, and particularly preferably 1 to 5.
However, x, y, and z must be evaluated by removing their effects when a metal salt is contained as an impurity or when the material has water that is not incorporated into the internal structure of the Prussian blue type complex. ..
Further, a solvent other than water and a material that does not appear positively in the composition, such as other ions as impurities, may be contained.

The crystal structure of the metal cyano complex is generally the face-centered cubic structure shown in FIG. 1, but is not necessarily limited thereto. For example, K _0.67 Zn [Fe (CN) ₆ ] _0.67 · zH ₂ O takes a hexagonal crystal. The number of cyano groups coordinated to M'is generally 6, but a part of the cyano group may be substituted with a nitro group or the like, and there is no problem as long as it is 4 to 8 or less.

The main absorption in the visible light region of the metal cyano complex is dd transition or charge transfer. In the metal cyano complex, NH ₃ is coordinated and adsorbed to the exposed metal ion portion, and the energy value and the number of electrons occupied by each orbit of the electron of the metal ion are changed. It is considered that the more metal ions exposed at this time, the larger the amount of change in the electronic state when the ammonia is coordinated and adsorbed, and the more the color changes in the presence of lower concentration ammonia gas.

The ammonia gas indicator of the present invention contains the metal cyano complex as a main component, and by adjusting the value of (1-y) _{in the above composition formula A x} M [M'(CN) ₆ ] _y · zH _{2 O,} It is an indicator showing a visible color change when brought into contact with a medium containing ammonia gas. Further, the ammonia gas indicator of the present invention can be used as an ammonia gas concentration indicator by using an indicator having a threshold value of the ammonia gas concentration at which a color change occurs, and further, the ammonia gas indicator of the present invention can be used. By changing at least one of x, y and z in the above composition formula, the color of the threshold value and / or the color change at the threshold value can be changed.
Hereinafter, it will be described with reference to FIG. 1 described above.

As shown in the figure on the left side of FIG. 1, _{there is no [M'(CN) 6} ] defect in the crystal structure when y = 1, but when 0 <y <1 as shown in the figure on the right side of the same, when 0 <y <1. There are 1-y [M'(CN) ₆ ] defects, and one [M'(CN) ₆ ] defect has 6 exposed metal ions. For example, in a metal cyano complex whose composition is represented by A _x M [M'(CN) ₆ ] _y , there are 6 (1-y) exposed metal ions.

In the present invention, when the defect rate (1-y) of this [M'(CN) ₆ ] is equal to or higher than a certain value, a visible color change occurs when the product is brought into contact with a medium containing ammonia gas, resulting in ammonia. Can be used as a gas indicator. Further, by changing the defect rate (1-y) of the [M'(CN) ₆ ], in other words, by changing the ratio (1 / y) of M and M', the ammonia gas that causes a color change. Since the concentration threshold value can be made different, it can be used as an ammonia gas concentration indicator.
Further, since the water molecule (zH ₂ O) in the above composition formula is also present in the defective portion of the above [M'(CN) ₆ ], the threshold concentration of the ammonia gas changes depending on the value of z. do. Further, the cations such as potassium and cesium represented by A are generally located in the face-centered cubic lattice shown in FIG. 1, and one side is half the size of the lattice constant. Since it is located near each center of the body, it is not related to the defect rate (1-y), but by changing the value of x according to the cation indicated by A, the threshold value of the ammonia gas concentration and / Alternatively, the color of the color change at the threshold value can be changed.

The method for synthesizing the metal cyano complex is not particularly limited, but a method capable of uniformly achieving the desired composition is preferable. Further, the surface of the complex may be modified with various materials for the convenience of processing. As a specific method, for example, the methods described in JP-A-2006-256954, JP-A-2013-173077, and the like can be used. In particular, since the reaction between ammonia gas and metal cyano complex particles occurs on the particle surface, it is desirable to use particles having a high specific surface area and a small particle size. It is preferable to use a microphone mixer as a method for synthesizing metal cyano complex nanoparticles.

Further, for various reasons, even if it is compounded with other materials, there is no problem as long as it contains a metal cyano complex and functions as an ammonia gas indicator. For example, it may be supported on fibers, paper made from fibers, woven fabric, or non-woven fabric, or may be mixed with a binder such as a polymer to form granules.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not construed as being limited thereto.

(Adjustment example 1)
<Preparation of C o -Co-cyano complexes>
A Co-Co cyano complex (K _x Co [Co (CN) ₆ ] _y ) was prepared as follows.
1.903 to 2.855 g of cobalt chloride hexahydrate was dissolved in pure water to a concentration of 20 mL to prepare an aqueous solution containing 0.40 to 0.60 mol / L of cobalt ions. Further, 2.69 g of potassium hexacyanocarboxylate was dissolved in pure water to a concentration of 20 mL to prepare a solution having 0.40 mol / L of hexcyanocobalate ions. 20 mL of cobalt ion solution of each concentration and 20 mL of hexacyanocobalt acid ion solution are mixed, and the assumed defect rate (1- y ) is 0.00, 0.05, 0.10, 0.15, 0.20, 0. Suspensions of eight C0-Cocyano complexes of 0.25, 0.30 and 0.33 were obtained.

After stirring 40 mL of the obtained liquid with a magnetic stirrer overnight, 40 mL of MilliQ water was added after solid-liquid separation by a centrifuge, and the washing step of centrifuging again was repeated 6 times. Then, it was vacuum dried to obtain a powder.
When the obtained powder was evaluated by PXRD (D2 phaser, manufactured by Bruker AXS), it had a crystal structure having a space group Fm-3m similar to _{Prussian blue (Fe 4} [Fe (CN) ₆ ] _3). The assumed defect rates (1-y) are 0.00, 0.05, 0.10, 0.15, 0.20, 0.25, 0.30, and 0.33, respectively. These sample names are Co-Co0.00, Co-Co0.05, Co-Co0.10, Co-Co0.15, Co-Co0.20, Co-Co0.25, Co-Co0.30, Co-, respectively. I named it Co0.33.

(Adjustment example 2)
<Preparation of A-Co-Fecyano complex (A = Cs, Rb, K, NH _4)>
A cyano complex having a constant Co / Fe ratio and different metal ions of A was prepared by the following procedure.
0.1903 g of cobalt chloride hexahydrate was dissolved in pure water to a concentration of 2 mL to prepare an aqueous solution containing 0.2 mol / L of cobalt ions. Further, 2.196 g of potassium ferrocyanide trihydrate plus one of alkali metal chlorides (0.3505 g of cesium chloride, 0.2516 g of rubidium chloride, 0.1552 g of potassium chloride, 0.1113 g of ammonium chloride) was added. It was dissolved to make 2.6 mL, and a solution of 0.8 mol / L of each alkali metal ion was prepared. A cobalt chloride solution and a potassium ferrocyanide solution containing each alkali metal ion were mixed and squeezed overnight in an environment of 1000 rpm and 40 ° C. in a stool (SI-300C, AS ONE). The solution after rinsing was filtered with a 0.45 micromesh filter, and 5 mL of pure water was filtered on the filtrate to perform desalting treatment. The obtained filtrate was dried together with the filter in an electric furnace at 60 ° C. for 30 minutes to obtain _{sample powders CsCoFe, RbCoFe, KCoFe, and NH 4 CoFe containing each alkali metal inside.}

When the color of each obtained sample was visually confirmed, CsCoFe was light green, RbCoFe was dark blue, KCoFe was purplish brown, and NH ₄ CoFe was reddish brown.
As a result, it was found that the color of the Co-Fe cyano complex is influenced not only by the C0 / Fe ratio but also by the type of A ion contained therein.

(Adjustment example 3)
<Preparation of Cs-Co-Fecyano complex>
The Cs-Co-Fecyano complex was prepared by the following procedure.
A solution of 0.516 g of cobalt chloride hexahydrate in 20 mL of ultrapure water and 0.672 to 5.376 g of cesium chloride and potassium hexacyanoferrate trihydrate in 20 mL of ultrapure water. 11 types with different Co / Fe concentration ratios by mixing 1.69 to 13.5 g of the dissolved solution, putting it in a 50 mL centrifuge tube, and then hydrating it overnight at 40 ° C using a constant temperature agitator SI300C. Was synthesized. After the shaving, the washing step by centrifugation was repeated 6 times in the same manner as in the above-mentioned Adjustment Example 1, and then the powder was obtained by vacuum drying.
From the Co / [Fe (CN) ₆ ] concentration ratio at the time of synthesis, each sample was selected as Co / Fe = 0.5, Co / Fe = 1.0, Co / Fe = 1.1, Co / Fe = 1.2, Co / Fe = 1.3, Co. We named them /Fe = 1.4, Co / Fe = 1.5, Co / Fe = 1.6, Co / Fe = 1.7, Co / Fe = 1.8, Co / Fe = 1.9, Co / Fe = 2.0, Co / Fe = 4.0. Samples with a small Co / Fe value have few defects. When the obtained sample was analyzed by PXRD, it was found that it had a crystal structure of Fm-3m similar to Prussian blue.
It should be noted that Cs, which is a monovalent cation, is incorporated into the crystal only to maintain the charge balance between _{Co (divalent cation) and [Fe (CN) 6] (tetravalent anion), which is a defect.} Cs is not related to the magnitude of the rate, and as described above, it is determined only by the ratio of Co and Fe. Since the valences of Co and [Fe (CN) ₆ ] are actually determined, x = (4y-2) can be expressed from the request for charge balance when there are no other ions.

(Adjustment example 4)
<Preparation of Fe-Co cyano complex>
2.386 g of iron (II) chloride tetrahydrate in Fe-Co cyano complex was dissolved in MilliQ water to make 20 mL, and iron ions were made 0.6 mol / L, and 2.69 g of potassium hexacyanocarboxylate was added. An Fe-Co cyano complex suspension was prepared by mixing those dissolved in MilliQ water to 20 mL. This suspension was washed 6 times in the same manner as in Preparation Example 1 and then vacuum dried to obtain a powder of Fe-Cocyano complex. The assumed composition of this Fe-Co cyano complex is Fe [Co (CN) ₆ ] _2/3 , and about 1/3 of the [Co (CN) ₆ ] sites are missing (Fe / Co). = 3/2 , assumed defect rate (1-y) = 1/3).

(Example 1)
<Color change of Co-Co cyano complex _{under pure NH 3 gas environment>}
The eight Co-Co cyano complexes obtained in Adjustment Example 1 were placed on graph paper in a gas desiccator, and the color change of the Co-Co cyano complex when the inside of the desiccator was replaced with ammonia gas was observed.
FIG. 2 is a photograph showing the observation results, and the initial state is shown on the left and the state in ammonia gas is shown on the right.
As shown in FIG. 2, Co-Co0.30 and Co-Co0.33 and the samples having a large defect rate changed their colors significantly in the ammonia environment. FIG. 3 shows changes in RGB values of each composition when the color information of the sample of each photograph is extracted in RGB units. In the figure, the black colored mark and the solid line indicate the initial state, and the gray mark and the dotted line indicate the state in ammonia gas.
As a result, it was found that the color change of the Co-Co cyano complex in a pure NH ₃ gas environment differs depending on whether the defect rate (1-y) is visible or not.

(Example 2)
<Color change of Cs-Co-Fecyano complex under low concentration NH _{3 gas environment>}
Using a sample of Co / Fe = 0.5 to 4.0 obtained in Preparation Example 3, it was a small amount of each smeared paper, dried for 1 hour in a state of 100% N ₂ gas flow at 60 ° C., these samples Of these, Co / Fe = 1.1 to 4.0 changed to dark green.
In addition, when each sample was circulated with 0.25, 1.5, 10, 30, 100, 1000 ppmv of ammonia gas containing no water, the samples excluding Co / Fe = 0.5 and 1.0 had an ammonia concentration. Along with the rise, color changes occurred as follows.
Co / Fe = 1.1 was 0.25 ppmv, Co / Fe = 1.5 was 10 pppmv, and changed from dark green to light brown, and Co / Fe = 1.1-4.0 changed to reddish brown at a concentration of 100 ppmv or higher. ..
In this way, the Co / Fe-1.1-4.0 sample has a different ammonia concentration for color change depending on the synthesis rate.

(Example 3)
In order to clarify the ammonia adsorption behavior of the samples actually drawn, the ammonia adsorption isotherms of the four types of samples were measured as follows.
The sample of Co / Fe = 0.5, 1.1, 1.5, 4.0 obtained in Adjustment Example 3 was vacuum dried at 100 ° C. for 24 hours, and then adsorbed with ammonia gas at 25 ° C. by a low concentration gas adsorber (BELSORP-MAXII). The quantity was evaluated. At this time, the partial pressure of ammonia in the container was converted into a concentration and displayed. For example, the pressure of 0.001 bar of ammonia corresponds to the partial pressure of ammonia in the air containing 1000 ppmv of ammonia, so this is described as 1000 ppmv.
The results are shown in FIG.
As shown in FIG. 4, the amount of adsorbed ammonia gas shows a sharp rise at 4 to 10 ppmv (volume of gaseous ammonia in the volume inside the container), and it is related to the concentration of the sharp rise of adsorption and the starting concentration of color change. Became clear.

(Example 4)
<Ammonia gas leak confirmation test using Fe-Co cyano complex>
The Fe-Cocyano complex obtained in Adjustment Example 4 was dissolved in water, smeared on the surface of a 6φ tube and dried to dryness, and then a cut was made in the tube of the smeared portion with a cutter. A needle valve was connected to one of the tubes, and a syringe containing ammonia gas was connected to the other, and the syringe was pushed to fill the tube with ammonia gas and raise the internal pressure. Ammonia gas leaked from the cut in the tube, and the color of the Fe-Cocyano complex near the cut changed.
FIG. 5 shows the color change of the Fe-Co cyano complex before and after the contact with ammonia by the RBG parameter from the image. This revealed that the Fe-Cocyano complex can be used for visual ammonia leakage check.

Claims (8)

The main composition is the general formula A _x M [M'(CN) ₆ ] _y · zH ₂ O
[In the formula, M is a group consisting of vanadium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, copper, silver, zinc, lantern, europium, gadolinium, lutetium, barium, strontium, and calcium. Represents one or more metal atoms selected from, where M'is one or two selected from the group consisting of vanadium, chromium, molybdenum, tungsten, manganese, iron, ruthenium, cobalt, nickel, platinum, and copper. Representing the above metal atoms, A represents one or more cations selected from the group consisting of hydrogen, lithium, sodium, potassium, ruthenium, ammonium and strontium, x is 0 to 3, y is 0. 0-1.0, z represents a numerical value of 0-6. ]
A method of using the metal cyano complex shown in (1) as an ammonia gas indicator that causes a visible color change when brought into contact with a medium containing ammonia gas.
[M'in the general formula, which is assumed from the concentration ratio (1 / y) of M and M'at the time of manufacturing the metal cyano complex so as to have a threshold value of the ammonia gas concentration that causes the color change. (CN) _6] wherein supposed defect rate temper pollock Rukoto (1-y) of the. The method of claim 1 in which the threshold of the ammonia gas concentration by using a plurality of different metal cyano complex, and judging the ammonia gas concentration. Prior following general formula, M and M 'are cobalt, A is potassium, according to claim 1 or 2, wherein the assumed defect rate (1-y) is used a metal cyano complex is 0.30 or more Method. In the above general formula, claim 1 or 2 using a metal cyano complex in which M is cobalt, M'is iron, A is cesium, and the assumed defect rate (1-y) is 0.10 or more. The method described in. In the above general formula, claim 1 or 2 using a metal cyano complex in which M is iron, M'is cobalt, A is potassium, and the assumed defect rate (1-y) is 1/3 or more. The method described in. The main composition is the general formula A _x M [M'(CN) ₆ ] _y · zH ₂ O
[In the formula, M is a group consisting of vanadium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, copper, silver, zinc, lantern, europium, gadolinium, lutetium, barium, strontium, and calcium. Represents one or more metal atoms selected from, where M'is one or two selected from the group consisting of vanadium, chromium, molybdenum, tungsten, manganese, iron, ruthenium, cobalt, nickel, platinum, and copper. Representing the above metal atoms, A represents one or more cations selected from the group consisting of hydrogen, lithium, sodium, potassium, ruthenium, and lutetium, x is 0 to 3, y is 0.1 to 0.1. 1.0 and z represent numerical values from 0 to 6. ]
The active ingredient is the metal cyano complex indicated by
The visible color change when in contact with the medium containing ammonia gas shown a to ammonia gas indicator,
Prior following general formula, M and M 'are cobalt, A is potassium, the a M during manufacture of the metal-cyano complexes M' concentration ratio of (1 / y) estimated from, in the general formula Ammonia gas indicator in which the assumed defect rate (1-y) of [M'(CN) ₆ ] is 0.30 or more. The main composition is the general formula A _x M [M'(CN) ₆ ] _y · zH ₂ O
[In the formula, M is a group consisting of vanadium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, copper, silver, zinc, lantern, europium, gadolinium, lutetium, barium, strontium, and calcium. Represents one or more metal atoms selected from, where M'is one or two selected from the group consisting of vanadium, chromium, molybdenum, tungsten, manganese, iron, ruthenium, cobalt, nickel, platinum, and copper. Representing the above metal atoms, A represents one or more cations selected from the group consisting of hydrogen, lithium, sodium, potassium, ruthenium, and lutetium, x is 0 to 3, y is 0.1 to 0.1. 1.0 and z represent numerical values from 0 to 6. ]
The active ingredient is the metal cyano complex indicated by
The visible color change when in contact with the medium containing ammonia gas shown a to ammonia gas indicator,
In the above general formula, M is cobalt, M'is iron, and A is cesium, which is assumed from the concentration ratio (1 / y) of M and M'at the time of producing the metal cyano complex. An ammonia gas indicator in which the assumed defect rate (1-y) of [M'(CN) ₆ ] in the general formula is 0.10 or more. The main composition is the general formula A _x M [M'(CN) ₆ ] _y · zH ₂ O
[In the formula, M is a group consisting of vanadium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, copper, silver, zinc, lantern, europium, gadolinium, lutetium, barium, strontium, and calcium. Represents one or more metal atoms selected from, where M'is one or two selected from the group consisting of vanadium, chromium, molybdenum, tungsten, manganese, iron, ruthenium, cobalt, nickel, platinum, and copper. Representing the above metal atoms, A represents one or more cations selected from the group consisting of hydrogen, lithium, sodium, potassium, ruthenium, and lutetium, x is 0 to 3, y is 0.1 to 0.1. 1.0 and z represent numerical values from 0 to 6. ]
The active ingredient is the metal cyano complex indicated by
The visible color change when in contact with the medium containing ammonia gas shown a to ammonia gas indicator,
In the above general formula, M is iron, M'is cobalt, and A is potassium, which is assumed from the concentration ratio (1 / y) of M and M'at the time of producing the metal cyano complex. Ammonia gas indicator in which the assumed defect rate (1-y) of [M'(CN) ₆ ] in the general formula is 1/3 or more.

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