JP2020099899A - Pollutant removing agent, pollutant removing member, and pollutant removing method - Google Patents

Abstract

To provide a pollutant removing agent that can adsorb various pollutants and has a less concern for re-release of the adsorbed pollutants.SOLUTION: Provided is a pollutant removing agent comprising a metal cyano complex represented by the following general formula (1). MNX[MC(CN)6] -- (1). [In the formula (1), MN represents at least one selected from the group consisting of Na, K, Mn, Fe, Co, Ni, Cu, Ag and Zn, and MC represents Fe(III), and x is 0.5 to 3.].SELECTED DRAWING: None

Description

The present invention relates to a contaminant removing agent, a contaminant removing member, and a contaminant removing method.

In recent years, interest in odors in daily life has increased, and reduction of odors such as unpleasant odors and malodors has been desired. There are various sources of odors in the real environment, such as toilets, kitchens, human bodies, etc. In general, odors are composed of multiple pollutants rather than a single substance. It is known to use activated carbon as a countermeasure against such an odor (for example, Patent Document 1).

Representative examples of pollutants include sulfur-based compounds such as methyl mercaptan and dimethyl sulfide, which are designated as specific malodorous substances in the Odor Control Law, and basic compounds such as trimethylamine. For example, although the above-mentioned activated carbon has adsorption ability for both of them, since the mechanism of adsorption is physical adsorption, there is a problem that the adsorbed pollutants are re-released, and the adsorption capacity tends to be small accordingly. is there.

International Publication No. 2016/171094

By the way, a method of adsorbing contaminants by chemical adsorption instead of physical adsorption is also known. Re-emission of pollutants is unlikely to occur with a scavenger using chemisorption. However, such a scavenger generally has only a specific material-specific adsorption capacity. Therefore, it is necessary to combine a plurality of scavengers in order to simultaneously remove a plurality of types of pollutants such as sulfur compounds and basic compounds as described above, which is extremely high cost compared to the case of using activated carbon. turn into.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a pollutant remover capable of adsorbing various pollutants and less likely to re-release the adsorbed pollutants. Another object of the present invention is to provide a contaminant removing member including a contaminant removing agent, and a contaminant removing method.

The inventors of the present invention have conducted extensive studies to solve the above-mentioned problems. As a result, in the Prussian blue type cyano complex, the coordination structure generated in the combination of specific metal ions is extremely important for the adsorption of contaminants. The present invention has been completed and the present invention has been completed.

The present invention provides a contaminant removing agent containing a metal cyano complex represented by the following general formula (1).
^{_{M N x [M C (CN}} ) 6] ··· (1)
[In the formula (1), M ^N represents at least one selected from the group consisting of Na, K, Mn, Fe, Co, Ni, Cu, Ag, and Zn, and M ^C represents Fe(III). , X is 0.5 to 3. ]

In the present invention, M ^N may be at least one selected from the group consisting of Cu, Ag and Zn.

In the present invention, the pollutant is at least selected from the group consisting of sulfur compounds, organic nitrogen compounds, nitrogen oxides, alcohols, aldehydes, fatty acids, ketones, ethers, esters, and aromatic hydrocarbons. It may be one kind.

In the present invention, the specific surface area of the metal cyano complex may be 200 to 1000 m ² /g.

The present invention also provides a contaminant removing member comprising the contaminant removing agent described above and a carrier carrying the contaminant removing agent.

In the contaminant removing member of the present invention, the carrier may have a honeycomb structure.

The present invention further provides a method for removing a pollutant, which comprises contacting the pollutant with the pollutant remover described above or the pollutant removal member described above.

According to the present invention, it is possible to provide a pollutant remover that can adsorb various pollutants and has less concern about re-release of the adsorbed pollutants. The present invention can also provide a contaminant removing member including a contaminant removing agent, and a contaminant removing method. The pollutant remover of the present invention is also excellent in adsorption amount.

Hereinafter, preferred embodiments of the present invention will be described in detail, but the present invention is not limited to the embodiments, and various modifications and changes are made within the scope of the gist of the present invention described in the claims. Is possible.

[Pollutants]
The pollutant remover of the present embodiment is intended to remove sulfur compounds, organic nitrogen compounds, nitrogen oxides, alcohols, aldehydes, fatty acids, ketones, ethers, esters, aromatic hydrocarbons, etc. Is.
Examples of the sulfur compound include thioether, thiophene, thiol, sulfoxide, sulfone, thioketone, sulfonic acid, sulfides and hydrogen sulfide.
Examples of the organic nitrogen compound include trimethylamine and urea.
The nitrogen oxides, for example _{NO, NO 2, N 2 O} , a so-called NO _x and the like, such as _{N 2 O 3, N 2 O} 4, N 2 O 5.
Examples of alcohols include methanol and ethanol.
Examples of aldehydes include formaldehyde and acetaldehyde.
Examples of the fatty acids include acetic acid and the like.
Examples of ketones include acetone and methyl ethyl ketone.
Examples of ethers include dimethyl ether and diethyl ether.
Examples of the esters include methyl acetate, ethyl acetate and the like.
Examples of aromatic hydrocarbons include toluene and xylene.
By properly adjusting the composition of the pollutant remover, the removal characteristics for each compound can be changed, and extremely high removal characteristics for a specific compound can be obtained. Such contaminant removing agent can be referred to as, for example, a trimethylamine removing agent, a sulfide removing agent, a thiol removing agent, a hydrogen sulfide removing agent, or the like.

[Pollutant remover]
The pollutant remover of the present embodiment contains a metal cyano complex (M ^N -M ^C cyano complex) represented by the following general formula (1).
_{^{M N x [M C (CN}} ) 6] ··· (1)

In formula (1), ^MN represents at least one metal ion selected from the group consisting of Na, K, Mn, Fe, Co, Ni, Cu, Ag, and Zn. From the viewpoint of excellent pollutant removal ability, Cu, Ag and Zn are preferable as ^MN .

In formula (1), M ^C represents a metal ion of Fe(III). [Fe(CN) ₆ ] ³⁻ is particularly excellent in the ability to remove pollutants.

The inventors presume the reason why the above metal cyano complex exhibits excellent characteristics as follows. From the knowledge of Prussian blue analogs as adsorbents and catalysts, it is considered that pollutants (adsorbents) adsorb on ^MN having coordination unsaturated sites. Therefore, it is important to select an optimum ^MN with a high affinity for contaminants. Furthermore, the Prussian blue analogues, it is known that there is a strong electron interactions between cyano ligands through the M ^C -M ^N. Therefore, it is considered that changing M ^C affects the electronic state around M ^N, which is the adsorption site, and changes the adsorption performance. For these reasons, it is considered that by optimizing the composition of M ^C and M ^N , which are the metal ions of the Prussian blue analog, with respect to the pollutant, excellent adsorption ability was exhibited. Since the metal cyano complex can adsorb the pollutant by chemisorption as described above, re-release of the pollutant can be suppressed.

From this point of view, in the formula (1), in order to express a higher pollutant removal ability, a mode in which M ^N is Cu and M ^C is Fe(III), and M ^N is Zn and M ^C is Fe( The embodiment of III) is mentioned as a suitable combination of M ^N and M ^C. In the case of these combinations, the removability for sulfur compounds tends to be particularly excellent. Further, an embodiment in which M ^N is Ag and M ^C is Fe(III) is also mentioned as a suitable combination of M ^N and M ^C. In the case of this combination, the removal property of hydrogen sulfide tends to be particularly excellent.

In the formula (1), x can be 0.5 to 3.0. However, from the viewpoint of increasing the number of coordination unsaturated sites, x is preferably 1.0 to 3.0, more preferably 1.0 to 2.5, and further preferably 1.1 to 2.0. 1 to 1.5 is particularly preferable. On the other hand, from the viewpoint of the valency that the constituent element ions can take, x can be set to 0.5 to 3.0, particularly 1.5 to 3.0, or 2 when ^MN is Ag. It may be from 0 to 3.0.

The average primary particle size of the metal cyano complex is preferably 200 nm or less from the viewpoint of the ability to remove contaminants, but may be 150 nm or less, 100 nm or less, 75 nm or less, 50 nm or less. May be The lower limit of the particle size is not particularly limited, but from the viewpoint of the ability to remove contaminants, it is preferably 4 nm or more, 10 nm or more, 20 nm or more, or 30 nm or more. The average primary particle diameter can be measured using powder X-ray structural analysis or the like. The average primary particle diameter of the metal cyano complex can be adjusted, for example, by the stirring speed of the aqueous solution mixing at the time of preparation.

The specific surface area of the metal cyanide complex is preferably from the viewpoint of the capability of removing contaminants is 200~1000m ² / g, more preferably 400 to 800 m ² / g, it is 500 to 700 m ² / g Is more preferable. The specific surface area can be measured by the BET method. The specific surface area of the metal cyano complex can be adjusted, for example, by the stirring speed of the aqueous solution mixing at the time of preparation.

The metal cyano complex can be produced based on, for example, JP-A-2006-256954 and JP-A-2013-173077, but the method is not particularly limited to these.

The pollutant remover may contain other components in addition to the metal cyano complex. Examples of such other components include a binder, an oxidizing agent, a reducing agent, and a conductive material. For example, by mixing a metal cyano complex and a binder, moldability can be imparted to the contaminant removing agent.

The contaminant removing agent may be in the form of particles (powder), a film, or a bulk body such as a block.

[Contaminant removal member]
The contaminant removing agent can be used as it is, but may be supported on a predetermined carrier. That is, the pollutant removal member of the present embodiment includes the pollutant remover described above and a carrier that carries the pollutant remover.

The carrier can be used without limitation as long as it does not impair the properties of the metal cyano complex.For example, organic fibers or inorganic fibers, yarns formed from these fibers, or formed from these fibers or yarns. Woven or non-woven fabric. A carrier having a honeycomb structure (honeycomb structure) formed from organic fibers or inorganic fibers may be used.

Examples of the method of supporting the contaminant removing agent on the carrier include the following. That is, a slurry containing a contaminant removing agent is prepared, and this is applied to a carrier by a known method such as wash coating or dipping, and then dried at 50 to 200°C. The amount of the contaminant removing agent carried can be 10 to 600 g/L.

[How to remove pollutants]
The contaminant removal method of the present embodiment includes a step of bringing a contaminant remover or a contaminant remover into contact with the contaminant.

The pollutant may be contained in the gas phase or may be contained in the liquid phase. Examples of the gas forming the gas phase include air, hydrocarbon gas, hydrogen gas, natural gas, city gas, propane gas and the like. Examples of the liquid that constitutes the liquid phase include water, organic solvents, ionic liquids, and the like.

The environment for implementing the method for removing contaminants can be -40 to 200°C, and preferably -20 to 150°C.

The present invention will be described in more detail based on the following examples, but the invention is not intended to be limited thereto.

(Preparation of metal cyano complex powder)
Various metal ^M metal nitrate solution corresponding to ^N L1 ^(M nitrate ^N), potassium hexacyanoferrate (II) solution _{^{L2 (M C = Fe (II}} ), K 4 [Fe (CN) 6] · 3H 2 O) and potassium hexacyanoferrate (III) solution ^L3 was prepared _{(M C = Fe (III)} , K 3 [Fe (CN) 6]). Table 1 shows M ^N and M ^C in each preparation example.

While stirring 200 mL of pure water, L1 and L2 or L1 and L3 were simultaneously charged by a liquid feed pump to obtain a precipitate. The concentrations of L2 and L3 were fixed at 0.12 mol/L, and the concentration of L1 was changed so as to have a stoichiometric ratio. The feeding rate of L1 to L3 was 50 mL/min, and the feeding time was 10 minutes.

After the completion of the addition of the aqueous solution, the mixture was further stirred and held for 10 minutes to prepare a slurry containing the metal cyano complex powder. Then, the precipitate in the slurry was separated using a centrifuge (H-2000B manufactured by Kokusan Co., Ltd.) (centrifuge condition: 10,000 rpm, 15 minutes). The obtained precipitate was washed with pure water three times using a centrifuge. The washed precipitate was dried at 60° C. in a dryer and then crushed in a mortar to obtain a metal cyano complex powder in each example.

(Analysis of powder)
The resulting metal cyano complex powder was analyzed as follows. The analysis results are shown in Table 1.

a) The crystal structure of each metal cyano complex powder was analyzed by powder X-ray diffraction and infrared spectroscopy. The powder in each Preparation Example had a structure represented by the general formula M ^N _X [M ^C (CN) ₆ ].
b) The average primary particle diameter of each metal cyano complex powder was calculated from the peak width of powder X-ray diffraction. Scherrer's formula was used for the calculation.
c) The specific surface area of each metal cyano complex powder was measured by the BET method (gas: N ₂ , pretreatment: 100° C. for 4 hours, in N ₂ gas stream).
d) The M ^N /M ^C ratio (x) of each metal cyano complex powder was determined by fluorescent X-ray analysis.

(Preparation of honeycomb structure carrying metal cyano complex powder)
The slurries containing the metal cyano complex powders obtained in Preparation Examples 10 and 13 were each washed with pure water three times using a centrifuge (H-2000B manufactured by Kokusan Co., Ltd. (centrifuge condition: 10000 rpm, 15 minutes). A corrugated honeycomb structure (length 200 mm, width 200 mm, thickness 12 mm, cell density; 420 cells per square inch) was immersed in the washed slurry. Then, the honeycomb structure is dried at 60° C. to obtain a honeycomb structure carrying the metal cyano complex powder obtained in Preparation Example 10 and a honeycomb structure carrying the metal cyano complex powder obtained in Preparation Example 13. It was In each case, the supported amount of the metal cyano complex powder was adjusted to be 50 g/L.

(Evaluation of removability of pollutants)
0.5 g of each metal cyano complex powder was spread on a watch glass, and this was left to stand in a closed container of 30 L (room temperature, humidity 50% RH). A pollutant was injected from a ventilation hole provided in the closed container, and a stirring fan in the container was operated to bring the contaminant into contact with the remover. The pollutant concentration in the container was measured after a lapse of a predetermined time, and the removal rate of the pollutant was obtained. For some of the powders, the pollutant injection and the removal rate measurement were repeated twice and three times after the pollutant concentration measurement. The honeycomb structure carrying the metal cyano complex powder was evaluated in the same manner as above, except that the honeycomb structure was attached to a stirring fan and allowed to stand in a 30 L closed container. The results are shown in Table 2.

The pollutants prepared and the injection amount are as follows.
Trimethylamine: 100 ppm (measurement and reinjection every 10 minutes)
Dimethyl sulfide: 100 ppm (measurement and reinjection every 30 minutes)
Methyl mercaptan: 30 ppm (measurement and reinjection every 20 minutes)
Dimethyl disulfide: 100 ppm (measurement and reinjection every 30 minutes)
Hydrogen sulfide: 100 ppm (measurement and reinjection every 30 minutes)

Claims (7)

A contaminant removing agent comprising a metal cyano complex represented by the following general formula (1).
^{_{M N X [M C (CN}} ) 6] ··· (1)
[In the formula (1), M ^N represents at least one selected from the group consisting of Na, K, Mn, Fe, Co, Ni, Cu, Ag, and Zn, and M ^C represents Fe(III). Indicated, x is 0.5 to 3. ] The contaminant remover according to claim 1, wherein the ^MN is at least one selected from the group consisting of Cu, Ag, and Zn. The pollutant is at least one selected from the group consisting of sulfur compounds, organic nitrogen compounds, nitrogen oxides, alcohols, aldehydes, fatty acids, ketones, ethers, esters, and aromatic hydrocarbons. The pollutant remover according to claim 1 or 2. The contaminant removing agent according to claim 1, wherein the metal cyano complex has a specific surface area of 200 to 1000 m ² /g. A pollutant removal member comprising: the pollutant remover according to claim 1; and a carrier carrying the pollutant remover. The pollutant removal member according to claim 5, wherein the carrier has a honeycomb structure. A method for removing a pollutant, which comprises contacting the pollutant with the pollutant remover according to any one of claims 1 to 4 or the pollutant remover according to claim 5 or 6.