JP4228077B2 - Method for producing layered hydroxide having ion-exchangeable anions by decarboxylation of hydrotalcite - Google Patents
Method for producing layered hydroxide having ion-exchangeable anions by decarboxylation of hydrotalcite Download PDFInfo
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- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 title claims description 71
- 150000001450 anions Chemical class 0.000 title claims description 47
- GDVKFRBCXAPAQJ-UHFFFAOYSA-A dialuminum;hexamagnesium;carbonate;hexadecahydroxide Chemical compound [OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[OH-].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Mg+2].[Al+3].[Al+3].[O-]C([O-])=O GDVKFRBCXAPAQJ-UHFFFAOYSA-A 0.000 title claims description 32
- 229910001701 hydrotalcite Inorganic materials 0.000 title claims description 32
- 229960001545 hydrotalcite Drugs 0.000 title claims description 32
- 238000004519 manufacturing process Methods 0.000 title claims description 15
- 238000006114 decarboxylation reaction Methods 0.000 title description 28
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 68
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 46
- 238000000034 method Methods 0.000 claims description 28
- 238000005349 anion exchange Methods 0.000 claims description 25
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 23
- -1 aluminum ion Chemical class 0.000 claims description 22
- 239000007864 aqueous solution Substances 0.000 claims description 19
- 238000005342 ion exchange Methods 0.000 claims description 19
- 239000002253 acid Substances 0.000 claims description 16
- 150000003839 salts Chemical class 0.000 claims description 14
- 239000011780 sodium chloride Substances 0.000 claims description 11
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims description 10
- 229910021645 metal ion Inorganic materials 0.000 claims description 10
- 239000011777 magnesium Substances 0.000 claims description 9
- 230000008569 process Effects 0.000 claims description 7
- 229910052782 aluminium Inorganic materials 0.000 claims description 5
- 239000000203 mixture Substances 0.000 claims description 4
- JLVVSXFLKOJNIY-UHFFFAOYSA-N Magnesium ion Chemical compound [Mg+2] JLVVSXFLKOJNIY-UHFFFAOYSA-N 0.000 claims description 2
- 229910001425 magnesium ion Inorganic materials 0.000 claims description 2
- 239000010410 layer Substances 0.000 description 29
- 239000002245 particle Substances 0.000 description 29
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 24
- 239000000126 substance Substances 0.000 description 22
- 150000002500 ions Chemical class 0.000 description 21
- 238000006243 chemical reaction Methods 0.000 description 20
- 239000007858 starting material Substances 0.000 description 16
- 230000008859 change Effects 0.000 description 15
- 239000000460 chlorine Substances 0.000 description 14
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 12
- 239000001569 carbon dioxide Substances 0.000 description 12
- 229910002092 carbon dioxide Inorganic materials 0.000 description 12
- 229910052801 chlorine Inorganic materials 0.000 description 12
- 150000001875 compounds Chemical class 0.000 description 12
- 150000004679 hydroxides Chemical class 0.000 description 12
- 239000000047 product Substances 0.000 description 12
- 239000002244 precipitate Substances 0.000 description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 11
- BVKZGUZCCUSVTD-UHFFFAOYSA-M Bicarbonate Chemical compound OC([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-M 0.000 description 8
- 230000000694 effects Effects 0.000 description 8
- 229910002651 NO3 Inorganic materials 0.000 description 7
- 238000001914 filtration Methods 0.000 description 7
- 125000000129 anionic group Chemical group 0.000 description 6
- 239000012153 distilled water Substances 0.000 description 6
- 238000002329 infrared spectrum Methods 0.000 description 6
- 229910052757 nitrogen Inorganic materials 0.000 description 6
- 239000000843 powder Substances 0.000 description 6
- 239000000243 solution Substances 0.000 description 6
- 238000009835 boiling Methods 0.000 description 5
- 239000002734 clay mineral Substances 0.000 description 5
- 239000012528 membrane Substances 0.000 description 5
- 229910000000 metal hydroxide Inorganic materials 0.000 description 5
- 150000004692 metal hydroxides Chemical class 0.000 description 5
- 230000007935 neutral effect Effects 0.000 description 5
- 238000011084 recovery Methods 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 4
- 238000010276 construction Methods 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 238000012844 infrared spectroscopy analysis Methods 0.000 description 4
- 238000003786 synthesis reaction Methods 0.000 description 4
- 239000013585 weight reducing agent Substances 0.000 description 4
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 3
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 238000010521 absorption reaction Methods 0.000 description 3
- 230000009471 action Effects 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- 125000002091 cationic group Chemical group 0.000 description 3
- 239000002131 composite material Substances 0.000 description 3
- 239000013078 crystal Substances 0.000 description 3
- 238000004090 dissolution Methods 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 239000011229 interlayer Substances 0.000 description 3
- 229910052749 magnesium Inorganic materials 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 230000007246 mechanism Effects 0.000 description 3
- 239000011259 mixed solution Substances 0.000 description 3
- 229920000642 polymer Polymers 0.000 description 3
- 238000012545 processing Methods 0.000 description 3
- 241000894007 species Species 0.000 description 3
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 239000012298 atmosphere Substances 0.000 description 2
- 238000005452 bending Methods 0.000 description 2
- 230000033228 biological regulation Effects 0.000 description 2
- 238000000160 carbon, hydrogen and nitrogen elemental analysis Methods 0.000 description 2
- 239000003054 catalyst Substances 0.000 description 2
- 150000001768 cations Chemical class 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 description 2
- 229910000041 hydrogen chloride Inorganic materials 0.000 description 2
- 230000003993 interaction Effects 0.000 description 2
- 239000007791 liquid phase Substances 0.000 description 2
- 239000000178 monomer Substances 0.000 description 2
- 239000012071 phase Substances 0.000 description 2
- 238000000634 powder X-ray diffraction Methods 0.000 description 2
- 230000035484 reaction time Effects 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 238000001878 scanning electron micrograph Methods 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L sodium carbonate Substances [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 230000004580 weight loss Effects 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 238000004566 IR spectroscopy Methods 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 description 1
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 238000000862 absorption spectrum Methods 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 238000010306 acid treatment Methods 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical class [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 description 1
- SNAAJJQQZSMGQD-UHFFFAOYSA-N aluminum magnesium Chemical compound [Mg].[Al] SNAAJJQQZSMGQD-UHFFFAOYSA-N 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 150000001449 anionic compounds Chemical class 0.000 description 1
- 239000003125 aqueous solvent Substances 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 239000004202 carbamide Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-N carbonic acid Chemical compound OC(O)=O BVKZGUZCCUSVTD-UHFFFAOYSA-N 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 238000001311 chemical methods and process Methods 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 238000000975 co-precipitation Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000008034 disappearance Effects 0.000 description 1
- 238000000921 elemental analysis Methods 0.000 description 1
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- 238000002474 experimental method Methods 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 229910001412 inorganic anion Inorganic materials 0.000 description 1
- 150000002484 inorganic compounds Chemical class 0.000 description 1
- 229910010272 inorganic material Inorganic materials 0.000 description 1
- 159000000003 magnesium salts Chemical class 0.000 description 1
- 239000008204 material by function Substances 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 239000002114 nanocomposite Substances 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 239000002516 radical scavenger Substances 0.000 description 1
- 238000012552 review Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- 229910052938 sodium sulfate Inorganic materials 0.000 description 1
- 235000011152 sodium sulphate Nutrition 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000002076 thermal analysis method Methods 0.000 description 1
- 238000010792 warming Methods 0.000 description 1
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- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Polymerisation Methods In General (AREA)
Description
本発明は、層間に難イオン交換性の炭酸イオンを有したハイドロタルサイト、もしくは、類似の構造を持つ層状複水酸化物の処理により易イオン交換性の陰イオンを有する層状複水酸化物の製造方法に関する。
The present invention relates to a hydrotalcite having hardly ion-exchangeable carbonate ions between layers, or a layered double hydroxide having an easily ion-exchangeable anion by treating a layered double hydroxide having a similar structure. about the production how.
従来、粘土鉱物などの層状化合物を使用し、各種の陽イオンや陽イオン性の機能性有機物を包接することによって多くの層状化合物が開発されてきた（非特許文献１）。ハイドロタルサイトは、粘土鉱物と異なり、層自体が陽電荷を持ち、層間に陰イオンを有し、陰イオン交換性を有する無機化合物である。陰イオン性交換性の物質は、陽イオン交換性の化合物に比べ種類が極端に少なく、ハイドロタルサイトもしくは、層状複水酸化物はその代表的なものである。 Conventionally, many layered compounds have been developed by using a layered compound such as a clay mineral and including various cations and cationic functional organic substances (Non-patent Document 1). Unlike clay minerals, hydrotalcite is an inorganic compound having a positive charge in the layer itself, having an anion between layers, and having anion exchange properties. There are extremely few types of anionic exchangeable substances compared to cation exchangeable compounds, and hydrotalcite or layered double hydroxides are typical examples.
近年、層状複水酸化物の陰イオン交換性を利用して、二酸化炭素の捕捉に使用されており、また、層間に他の陰イオンを導入することにより、層間に機能性の分子や有機物をナノレベルで包接したナノ層状化合物が合成されており、さらに、表面積とその触媒作用から、触媒もしくは、触媒の担体としても多くの研究が行われている（非特許文献２）。 In recent years, it has been used to capture carbon dioxide by utilizing the anion exchange properties of layered double hydroxides, and by introducing other anions between layers, functional molecules and organic substances can be introduced between layers. Nano-layered compounds that have been included at the nano level have been synthesized, and many studies have been conducted on catalysts or catalyst carriers based on their surface area and their catalytic action (Non-patent Document 2).
通常、合成され生産されているハイドロタルサイトは、炭酸イオンを層間に有している層状複水酸化物であり、最近では、特に「尿素」を用いて、均一に核形成を行い、粒径の均一で制御されたハイドロタルサイトが合成されている（非特許文献３）。通常、炭酸イオン以外の陰イオンを含む層状複水酸化物では、包接させたい陰イオンを大量に含む溶液中でイオン交換させることにより、構造を変化させずに、当該陰イオンを含む層状複水酸化物に変換することができる。 The hydrotalcite that is usually synthesized and produced is a layered double hydroxide that has carbonate ions between the layers. Recently, using “urea” in particular, nucleation is performed uniformly, and the particle size is reduced. A uniform and controlled hydrotalcite is synthesized (Non-patent Document 3). Usually, in layered double hydroxides containing anions other than carbonate ions, the layered double hydroxides containing the anions are exchanged in a solution containing a large amount of anions to be included, without changing the structure. Can be converted to hydroxide.
しかし、炭酸イオンを含むハイドロタルサイトのような層状複水酸化物の場合、炭酸イオンが安定に層間に存在するためイオン交換性が極めて低く、ほとんどイオン交換が起こらないことから、その陰イオン交換剤としての用途は、極めて限られていた（非特許文献４）。 However, in the case of layered double hydroxides such as hydrotalcite containing carbonate ions, carbonate ions are stably present between the layers, so the ion exchange property is extremely low and almost no ion exchange occurs. The use as an agent has been extremely limited (Non-Patent Document 4).
そのため、陰イオン交換性の層状複水酸化物を合成するため、二酸化炭素を溶解していない脱炭酸の蒸留水を用い、窒素気流中など二酸化炭素の無い雰囲気で例えば、マグネシウム・アルミニウム層状複水酸化物の場合、マグネシウム塩、アルミニウム塩、と水酸化ナトリウム水溶液との共沈反応により、炭酸以外の陰イオン（例えば、硝酸イオン、塩素イオンなど）で、交換が容易な陰イオンを含む、層状複水酸化物を合成していた（非特許文献５）。 Therefore, in order to synthesize an anion-exchange layered double hydroxide, for example, magnesium / aluminum layered double water is used in a carbon dioxide-free atmosphere such as a nitrogen stream using decarboxylated distilled water in which carbon dioxide is not dissolved. In the case of oxides, a layer containing an anion other than carbonic acid (for example, nitrate ion, chlorine ion, etc.) and easily exchangeable by coprecipitation reaction of magnesium salt, aluminum salt and sodium hydroxide aqueous solution. A double hydroxide was synthesized (Non-patent Document 5).
また、別法では、加熱による構造変化を利用している。すなわち、５００℃程度の加熱により、ハイドロタルサイトは、構造変化を起こし、脱炭酸するが、得られた生成物を炭酸イオン以外の陰イオン（例えば、硝酸イオン、塩素イオンなど）を含む水溶液に投入することによって、その陰イオンを含む層状複水酸化物が再構築されることが知られている（非特許文献６）。この方法を用いて、二酸化炭素の捕捉という目的でこの反応を用いたり、また、この再構築で、任意の陰イオンが層間に入ることより、層間に機能性の分子や有機物をナノレベルで包接したナノ層状化合物が合成されてきたのである。 Another method uses structural changes caused by heating. That is, the hydrotalcite undergoes a structural change and decarboxylates by heating at about 500 ° C., but the obtained product is converted into an aqueous solution containing anions other than carbonate ions (for example, nitrate ions, chlorine ions, etc.). It is known that the layered double hydroxide containing the anion is reconstructed by introducing (Non-patent Document 6). Using this method, this reaction can be used for the purpose of capturing carbon dioxide, and any anion can enter the interlayer by this reconstruction, so that functional molecules and organic substances can be encapsulated between the layers at the nano level. Nanolayered compounds in contact have been synthesized.
しかし、前者の方法では、各々の組み合わせによって、粒径や均一性の条件が異なるた
め、合成条件の最適化が困難である。また、反応自体も雰囲気制御や二酸化炭素を除去した反応系の構築などで煩雑である。また、後者の方法では、加熱によって構造が変化しているため、再構築後の方向性が、出発物と同一とはいえず粒径や均一性に変化を起こし、また、５００℃の高温を利用するため、脱炭酸の意味でもかなり激しい条件を利用しており、エネルギー的にも時間的にも実用的でなく、不利であった。
However, in the former method, the conditions of particle size and uniformity differ depending on the combination, so it is difficult to optimize the synthesis conditions. Also, the reaction itself is complicated due to atmosphere control and construction of a reaction system from which carbon dioxide is removed. In the latter method, since the structure is changed by heating, the direction after the reconstruction is not the same as the starting material, and the particle size and uniformity are changed. In order to use it, the use of fairly severe conditions also in terms of decarboxylation was not practical in terms of energy and time, which was disadvantageous.
もし、合成が比較的楽な、粒径が制御された、しかも均一なハイドロタルサイトから、簡単な化学的手法によって、交換が容易な陰イオン（例えば、硝酸イオン、塩素イオンなど）を含む層状複水酸化物を、粒径や均一性に変化を及ぼすことがなく合成できるならば、工業的にもまた、研究・試験レベルにも広い応用が期待できる。これに関しては、確かに、これまで、0.01規定の塩酸を用いた方法が、報告されている（非特許文献７）。また、１５０℃の塩化水素ガスによる処理の報告もある（非特許文献８）。しかし、後者の方法は、危険性や反応条件の過激なことから、簡便な方法とは言えず、また、前者の方法においても、実際に反応を行ってみると、[実施例２]でも示したように、必ずしも脱炭酸イオンと溶解による重量減少のバランスがあり、重量減少なく脱炭酸イオンを行うことが事実上、不可能であり、完全な方法ではなかった。 If it is relatively easy to synthesize, particle size is controlled, and uniform hydrotalcite contains anions (eg, nitrate ions, chloride ions, etc.) that can be easily exchanged by simple chemical methods. If double hydroxides can be synthesized without changing the particle size and uniformity, a wide range of applications can be expected industrially as well as at research and test levels. In this regard, a method using 0.01 N hydrochloric acid has been reported to date (Non-Patent Document 7). There is also a report of treatment with hydrogen chloride gas at 150 ° C. (Non-patent Document 8). However, the latter method cannot be said to be a simple method due to the extreme risk and reaction conditions. Also, when the reaction is actually performed in the former method, it is also shown in [Example 2]. As described above, there is always a balance between decarboxylation ions and weight loss due to dissolution, and it is virtually impossible to perform decarboxylation ions without weight reduction, and this is not a complete method.
このように、ハイドロタルサイトから、簡単な化学的手法によって、交換が容易な陰イオン（例えば、硝酸イオン、塩素イオンなど）を含む層状複水酸化物を、粒径や均一性に変化を及ぼすことがなく、合成する方法は、従来存在していなかった。その結果、異なる無機の陰イオンを層間に導入したり、また、新規な機能性材料を合成する手法であるイオン交換法によってイオン性を持つ機能性有機物を導入して機能性層状複合体とするといったような、ソフト化学的な手法によって新規材料を合成し提供する試みは、ハイドロタルサイトから導出された層状複水酸化物を用いて行われることは、なされていなかった。 In this way, the layered double hydroxide containing anions (for example, nitrate ions, chlorine ions, etc.) that can be easily exchanged from hydrotalcite by a simple chemical method changes the particle size and uniformity. There has been no conventional method for synthesis. As a result, different inorganic anions are introduced between layers, or functional organic substances having ionicity are introduced by ion exchange, which is a technique for synthesizing new functional materials, to form functional layered composites. Attempts to synthesize and provide new materials by soft chemical techniques such as those described above have not been made using layered double hydroxides derived from hydrotalcite.
また、二酸化炭素は、地球温暖化の原因の大きな要素であり、排出の際の捕捉が、必要である。層状複水酸化物は、その目的で使用されており、無機の脱炭酸材料の代表的なものである。その脱炭酸には、既に述べたような、「再構築」という現象を利用したもので、５００℃程度の加熱によりハイドロタルサイトが構造変化を起こし、脱炭酸し、この生成物を二酸化炭素の捕捉に使うというものであり、エネルギー的にも時間的にも不利であった。しかし、この脱炭酸が、室温のような温和な条件で、しかも簡単な化学的手法によって達成され、さらに、陰イオン交換が容易な陰イオン（例えば、硝酸イオン、塩素イオンなど）を含む層状複水酸化物に変換して、繰り返し使用できるならば、二酸化炭素の捕捉サイクルとしても有望である。 Carbon dioxide is a major factor in causing global warming and needs to be captured when discharged. Layered double hydroxides are used for that purpose and are representative of inorganic decarboxylation materials. The decarboxylation uses the phenomenon of “reconstruction” as described above, and the hydrotalcite undergoes a structural change by heating at about 500 ° C. and decarboxylates. It was used for capture and was disadvantageous in terms of energy and time. However, this decarboxylation is achieved by a simple chemical method under mild conditions such as room temperature, and further, a layered complex containing anions (for example, nitrate ions, chloride ions, etc.) that can be easily anion-exchanged. If it can be converted to hydroxide and used repeatedly, it is also promising as a carbon dioxide capture cycle.
また、２次元の層状物は、他にも汎用ポリマーの機械的強度を向上させるためのフィラーとして注目されており、例えば粘土鉱物など２次元レイヤーを含む化合物が用いられているが、レイヤーの剥離が完全に行なわれない点やマトリックスとの親和性が充分でない点で問題があり、分散性などに多くの解決すべき課題が残っているものであった。層状複水酸化物の層は、粘土鉱物と異なり、陽イオン性であり、粘土では対応できない陰イオン性のモノマーを包接することができる。もし、層間に高分子のモノマーを包接し、反応を起こさせることができるなら、粘土鉱物の使用できないような高分子についても、用いることが可能となり、また、レイヤーまでの剥離が期待でき、機械的強度、ガスバリアー性の改善がおおいに期待できる。 Two-dimensional layered materials are also attracting attention as fillers for improving the mechanical strength of other general-purpose polymers. For example, compounds containing two-dimensional layers such as clay minerals are used. However, there is a problem in that the process is not completely performed and the affinity with the matrix is not sufficient, and many problems to be solved remain in dispersibility. Unlike clay minerals, the layered double hydroxide layer is cationic and can include anionic monomers that cannot be handled by clay. If a polymer monomer can be included between layers to cause a reaction, a polymer that cannot be used with clay minerals can be used, and peeling to the layer can be expected. The improvement of mechanical strength and gas barrier property can be greatly expected.
このようにハイドロタルサイトから、簡単な化学的手法によって、交換が容易な陰イオン（例えば、硝酸イオン、塩素イオンなど）を含む層状複水酸化物を、粒径や均一性に変化を及ぼすことがなく、合成出来るならば、実験室レベルから工業レベルまで、また、環境問題からナノテクノロジーまで広い分野で、ブレークスルーが期待できるが、従来、このような手法は開発されていなかった。
本発明は、難イオン交換性の炭酸イオンを層間に含むハイドロタルサイトから、簡単で温和な化学的手法によって、交換が容易な陰イオン（例えば、硝酸イオン、塩素イオンなど）を含む層状複水酸化物を、粒径や均一性に変化を及ぼすことなく得るための、実用性に富んだ極めて簡便な化学的合成手法を提供しようというものである。また、それにより、実用性に富んだ新たなハイドロタルサイトの脱炭酸手法を提供し、繰り返し二酸化炭素の脱着が可能なシステムの構築に資するものである。このようにして得られた易陰イオン交換性を示す層状複水酸化物は、陰イオン交換性を備えているためイオン交換によって容易に、炭酸イオンを含む他の陰イオンや、陽イオン性の機能性有機物質などの陰イオンと交換することが可能となるものである。 The present invention relates to a layered double water containing anions (for example, nitrate ions, chloride ions, etc.) that can be easily exchanged from a hydrotalcite containing hardly ion-exchangeable carbonate ions between layers by a simple and mild chemical method. The purpose of the present invention is to provide a practical and extremely simple chemical synthesis method for obtaining an oxide without changing the particle size and uniformity. In addition, it provides a new hydrotalcite decarboxylation method that is highly practical and contributes to the construction of a system that can repeatedly desorb carbon dioxide. The thus obtained layered double hydroxide exhibiting easy anion exchangeability has anion exchangeability, so it can be easily exchanged with other anions including carbonate ions and cationic anions. It can be exchanged for anions such as functional organic substances.
前記プロセスを簡便で実用的な脱炭酸プロセスとして利用することは勿論、それによってできた易陰イオン交換性を示す層状複水酸化物のイオン交換性を生かすことによって、該層状化合物に、簡単に機能性分子を導入することができ、これまでに存在しなかった新規な機能性層状化合物を提供することも可能となるものであり、その利用可能性は、新規化合物を提供する意味でも、また、環境問題の分野でも、極めて優れ実用性に富んでおり、意義が大きいといえる。 Of course, the above-mentioned process can be used as a simple and practical decarboxylation process, and by making use of the ion exchange property of the layered double hydroxide showing the easy anion exchange property produced thereby, the layered compound can be easily obtained. Functional molecules can be introduced, and it is also possible to provide a novel functional layered compound that has not existed before, and its availability is also in the sense of providing a new compound, In the field of environmental problems, it is extremely excellent and practical, and can be said to have great significance.
既に述べたように、これまで塩酸でハイドロタルサイトの処理を行った例がある。このとき、塩酸中のプロトンは、層間の炭酸イオンに容易に結びついて、炭酸水素イオンとなり、マイナス１価の電荷を持つようになるため、イオン交換性に変化が起こる、即ちよりイオン交換が容易になる、と考えられる。そして、水と層状複水酸化物の２つの相において、炭酸水素イオンと塩素イオンは、平衡状態にあり、平衡係数に応じて両方の相に分布しているといえる。この際、大量の塩素イオンがあるならば、炭酸水素イオンと塩素イオンの平衡が層間に塩素イオンが入るような方向に平衡がずれることは、ル・シャトリエの原理からも充分起こるであろうと考えられる。 As already mentioned, there are examples of hydrotalcite treatment with hydrochloric acid so far. At this time, protons in hydrochloric acid are easily combined with carbonate ions between the layers to become hydrogen carbonate ions and have a minus monovalent charge, so that the ion exchange property changes, that is, the ion exchange is easier. It is thought that it becomes. In the two phases of water and the layered double hydroxide, it can be said that the hydrogen carbonate ions and the chlorine ions are in an equilibrium state and are distributed in both phases according to the equilibrium coefficient. At this time, if there is a large amount of chlorine ions, it is considered that the equilibrium of hydrogen carbonate ions and chlorine ions will shift in the direction in which chlorine ions enter between the layers from Le Chatelier's principle. It is done.
これらのことから、酸処理の際に導入したい陰イオンを多量に添加することにより、ハイドロタルサイトから、脱炭酸が出来るのではとの考えに至った。発明者らは、以上の考えに立脚し、具体的には、ハイドロタルサイトを、塩酸と塩素陰イオンを含む水溶媒中に、投入すれば、高温での加熱や腐食性の強い塩化水素ガスなどの反応系を使わなくとも、脱炭酸イオンと、それにともない、易陰イオン交換性を示す層状複水酸化物への変換が合成可能ではないかとの考えに至った。 From these, it came to the idea that decarboxylation can be performed from hydrotalcite by adding a large amount of anions to be introduced during acid treatment. The inventors based on the above idea, specifically, if hydrotalcite is put into an aqueous solvent containing hydrochloric acid and chlorine anion, hydrogen chloride gas that is highly heated and corrosive is used. Even without using a reaction system such as the above, the inventors have come up with the idea that decarboxylation ions and conversion to layered double hydroxides that exhibit easy anion exchange can be synthesized.
以上の基本方針に基づき鋭意研究した結果、脱炭酸イオンの作用は低いが、ハイドロタ
ルサイトの粒径や外形、均一性が変化しない程度の希薄な塩酸を用い、その系に中性の塩酸塩（たとえば、塩化ナトリウムなど）を添加し、室温で作用させることにより、脱炭酸イオンが著しく促進され、外形・粒径・重量を保ったまま、極めて短時間で脱炭酸イオンが行われ、添加した陰イオンを含む層状複水酸化物に変換することを見出すに至った。
As a result of diligent research based on the basic policy described above, dehydrocarbonate ion has a low action, but dilute hydrochloric acid that does not change the particle size, shape, and uniformity of hydrotalcite, and neutral hydrochloric acid in the system. By adding (for example, sodium chloride) and allowing it to act at room temperature, decarboxylation ions are remarkably accelerated, and decarboxylation ions are added and added in an extremely short time while maintaining the external shape, particle size, and weight. It came to find out that it converted into the layered double hydroxide containing an anion.
また、酸としては、塩酸の他に、同じ規定濃度の他のプロトン性強酸である硝酸や硫酸も同じ効果をもたらし、さらに中性の塩として塩酸塩以外に硝酸塩や硫酸塩を用いることにより、生成物に取り込まれる陰イオンの種類を変化させることが可能であることを見いだした。 In addition to hydrochloric acid, nitric acid and sulfuric acid, which are other protic strong acids with the same specified concentration, also have the same effect as acid, and by using nitrate or sulfate other than hydrochloride as neutral salt, It has been found that the type of anion incorporated into the product can be changed.
以上から、本発明者らにおいては、室温という温和な条件で、しかも極めて短時間で、酸と大量の塩素イオンなどの陰イオンを含む混合溶液により、粒径や均一性に変化を及ぼさずに、難イオン交換性のハイドロタルサイトを、脱炭酸イオンさせ、易交換性陰イオン（例えば、硝酸イオン、塩素イオンなど）を含む層状複水酸化物へ変換することに成功したものである。 From the above, the present inventors do not change the particle size or uniformity with a mixed solution containing anions such as acid and a large amount of chlorine ions under a mild condition of room temperature and in a very short time. The present invention succeeds in converting a hardly ion-exchangeable hydrotalcite into a layered double hydroxide containing an easily exchangeable anion (for example, nitrate ion, chlorine ion, etc.) by decarboxylation.
すなわち、本発明は、以下（１）から（６）に記載する解決手段を講ずることによって達成されたものである。
（１）一般式； ＭｘＮ（ＯＨ）ｚ（ＣＯ３ ２−）〜０．５・ｎＨ２Ｏ（ 式中、xは、1 . 8≦ x≦ ４．２の数値範囲を示す。zは、２（ｘ＋１）を示す。Ｍは、２価の金属イオン。Ｎは、３価の金属イオン。nは、環境の湿度により変化するが、ほぼ２。）で表される組成を有し、ハイドロタルサイトに類似した構造を有する炭酸イオンを含む層状複水酸化物に、プロトン性の酸と陰イオン（Ｘ）の塩を含む混合水溶液を接触させて陰イオン交換を行い、層状複水酸化物中の炭酸イオンを水溶液に溶離し、溶離した層状複水酸化物中の炭酸イオンサイトに陰イオン（Ｘ）を導入し、陰イオン交換性に富む層状複水酸化物を生成させることを特徴とする、陰イオン交換性層状複水酸化物の製造方法。
That is, the present invention has been achieved by taking the solutions described in (1) to (6) below.
(1) General formula; MxN (OH) z (CO 3 2− ) to 0.5 · nH 2 O (wherein x represents a numerical range of 1.8 ≦ x ≦ 4.2. Z is 2 (x + 1), M is a divalent metal ion, N is a trivalent metal ion, and n has a composition represented by 2 although it varies depending on the humidity of the environment. A layered double hydroxide containing carbonate ions having a structure similar to that of talcite is contacted with a mixed aqueous solution containing a salt of a protic acid and an anion (X) to perform anion exchange. It is characterized by eluting the carbonate ion in the aqueous solution and introducing an anion (X) into the carbonate ion site in the eluted layered double hydroxide to produce a layered double hydroxide rich in anion exchange. A method for producing an anion-exchange layered double hydroxide.
（２） 該陰イオン交換操作が、室温から１００℃未満の低温領域で行なわれる、前記（１）項に記載の陰イオン交換性層状複水酸化物の製造方法。
（３） 該プロトン性の酸が塩酸であり、陰イオン（X）の塩が塩化ナトリウム（食塩）
である、前記（１）項に記載の陰イオン交換性層状複水酸化物の製造方法。
（４） 該水溶液中のプロトン性の酸濃度が、０．００００５〜０．０２５規定であり、陰イオン（X）の塩濃度が２重量％以上である、前記（１）または（３）項に記載の陰イ
オン交換性層状複水酸化物の製造方法。
（５） 該一般式で示される出発層状複水酸化物が、式中金属イオンＭがマグネシウムイオンＭｇであり、式中３価の金属イオンＮがアルミニウムイオンＡｌであるハイドロタルサイトである、前記（１）項に記載の陰イオン交換性層状複水酸化物の製造方法。
（６） 該陰イオン交換性層状複水酸化物における陰イオンが塩素イオンである、前記（１）ないし（５）の何れか１項に記載の陰イオン交換性層状複水酸化物の製造方法。
(2) The method for producing an anion-exchange layered double hydroxide as described in (1) above, wherein the anion exchange operation is performed in a low temperature region from room temperature to less than 100 ° C.
(3) The protic acid is hydrochloric acid, and the salt of the anion (X) is sodium chloride (salt)
The method for producing an anion-exchanging layered double hydroxide as described in (1) above.
(4) The above item (1) or (3), wherein the concentration of the protic acid in the aqueous solution is 0.00005 to 0.025 N and the salt concentration of the anion (X) is 2% by weight or more. A process for producing an anion-exchange layered double hydroxide as described in 1.
(5) The starting layered double hydroxide represented by the general formula is a hydrotalcite in which the metal ion M is magnesium ion Mg and the trivalent metal ion N is aluminum ion Al in the formula (1) The manufacturing method of the anion exchange layered double hydroxide as described in the item.
(6) The method for producing an anion-exchange layered double hydroxide according to any one of (1) to (5), wherein the anion in the anion-exchange layered double hydroxide is a chlorine ion. .
以上において、一般式で示される出発原料である層状複水酸化物の化学式について、炭酸イオン（CO3 2-）を〜0.5としたのは、０．５において最も炭酸イオンが多く、イオン交換が最も困難な組成を規定したものであり、本発明はこの領域も含め実施可能な領域を規定しているものである。 In the above, regarding the chemical formula of the layered double hydroxide, which is the starting material represented by the general formula, the carbonate ion (CO 3 2- ) is set to be ~ 0.5. The most difficult composition is defined, and the present invention defines a feasible region including this region.
さらに、（１）及びその実施態様項である（２）〜（６）において生成する陰イオン交換性層状複水酸化物は、一般式；ＭｘＮ（ＯＨ）ｚ（ＣＯ３ ２−）〜０．５・ｎＨ２Ｏで表される出発物質の(ＣＯの交換の程度によって、完全に（Ｘ）によって置換された状態のものから(ＣＯ３ ２−)炭酸イオンが、陰イオン（Ｘ） と陰イオン交換したものであるので、その交換の程度によって、完全に（Ｘ）によって置換された状態のものから(ＣＯ３ ２−)が残存しているものまで広い領域のものが得られ、本発明の陰イオン交換性層状複水酸化物は、陰イオン（Ｘ）が導入されたことによって炭酸イオンが残存しているものでも、その生成物は陰イオン交換が容易であることから、発明の態様として含むものである。完全に脱炭酸イオン処理されてなる生成物は、一般式；ＭｘＮ（ＯＨ）ｚ（Ｘ）・ｎＨ２Ｏ （ 式中、xは、１．８≦ x≦４．２の数値範囲を示す。ｚは、２（ｘ＋１）を示す。Ｍは、２価の金属イオン。Ｎは、３価の金属イオン。nは、環境の湿度により変化するが、ほぼ２。）で表されるが、この組成のみに限定する趣旨ではない。
Furthermore, the anion-exchange layered double hydroxide produced in (1) and its embodiment items (2) to (6) has the general formula: MxN (OH) z (CO 3 2− ) 0 to. From the starting material represented by 5 · nH 2 O (where the CO is completely replaced by (X) depending on the degree of CO exchange, (CO 3 2− ) carbonate ions are converted to anions (X) and anions. Since the ions are exchanged, depending on the degree of exchange, those in a wide range from those completely substituted by (X) to those in which (CO 3 2− ) remains can be obtained. In the anion-exchange layered double hydroxide of the present invention, even though carbonate ions remain as a result of the introduction of the anion (X), the product can be easily anion-exchanged. Completely decarbonated ion treatment Is formed by the product of the general formula; MxN (OH) z (X ) · n H 2 O ( wherein, x is, .z showing the numerical range of 1.8 ≦ x ≦ 4.2, the 2 ( x + 1), M is a divalent metal ion, N is a trivalent metal ion, and n is approximately 2), although it varies depending on the humidity of the environment, but is limited to this composition. Not the purpose.
本発明は、上記の構成を講ずることによって、ハイドロタルサイトの外形・粒径・重量を保ったまま、極めて短時間で脱炭酸イオンが起こり、添加した陰イオンを含む層状複水酸化物に変換することに成功したものである。そして、この成功によって、二酸化炭素除去プロセスあるいは無機有機複合体を提供することにも成功したものである。 By adopting the above configuration, the present invention generates decarbonated ions in a very short time while maintaining the external shape, particle size, and weight of the hydrotalcite, and converts it into a layered double hydroxide containing the added anion. Has been successful. And with this success, we have also succeeded in providing a carbon dioxide removal process or inorganic-organic composite.
本発明は、従来知られていなかった、炭酸イオンを層間に有するハイドロタルサイトに代表される層状複水酸化物の簡便な脱炭酸イオンに成功したものであり、そのプロセス自体産業上利用しうるもので、その意義は大きい。加えて、得られる陰イオンを含む層状複水酸化物は、陰イオン交換が可能なため、他の陰イオンへの変換が可能であり、有機無機ナノ複合体を含む新化合物が合成でき、今後各種分野に大いに利用されることが期待される。例えば、再度、炭酸イオンと結びつくと、二酸化炭素の捕捉分離剤としての利用、が考えられる。さらに、このような二酸化炭素の捕捉剤としての用途のほかにも、陰イオン性機能性有機分子をイオン交換プロセスといった極めて簡単な操作によるいわゆるソフトケミカル的な反応によって、粒径や形状の制御された層状複水酸化物の層間に包接することができるため、新規な機能を有する新規物質の開発・促進につながるものと期待される。 The present invention has succeeded in simple decarboxylation of a layered double hydroxide represented by a hydrotalcite having carbonate ions between layers, which has not been conventionally known, and the process itself can be used industrially. It is significant. In addition, since the layered double hydroxide containing anions can be anion exchanged, it can be converted to other anions, and new compounds containing organic-inorganic nanocomposites can be synthesized. Expected to be widely used in various fields. For example, when combined with carbonate ions again, use as a carbon dioxide capture and separation agent can be considered. In addition to its use as a carbon dioxide scavenger, the particle size and shape are controlled by so-called soft chemical reactions by an extremely simple operation such as an ion exchange process for anionic functional organic molecules. Therefore, it is expected to lead to the development and promotion of new substances having new functions.
さらに、本発明は、任意の均一粒径の製造が可能となっている炭酸イオンを含む層状複水酸化物より、簡単な反応により、粒径・外形・重量を変化させること無く、任意の陰イオンを含む層状複水酸化物を提供できることを示しており、基板上に配向膜を形成するこ
とが可能であり、近年、注目されているような、配向性の高いナノデバイスの構築といった新しい応用分野にまで発展し、及ぶことが考えられ、そのもたらす作用効果は技術的に極めて大きな意義を有するものである。
Furthermore, the present invention provides a simple reaction from a layered double hydroxide containing carbonate ions, which can be produced with an arbitrary uniform particle size, without any change in particle size, external shape, and weight. It has been shown that layered double hydroxides containing ions can be provided, and it is possible to form an alignment film on a substrate, and new applications such as the construction of highly oriented nanodevices that have attracted attention in recent years It is conceivable to develop and extend to the field, and the effects brought about by it are extremely technically significant.
本発明の解決手段は、前述した通りであるが、以下、実施例に基づいて具体的に説明する。但しこれら実施例は、本発明を容易に理解するための一助として示したものであり、決して本発明を限定する趣旨ではない。また、当該製造方法の優位性を示すため、実施例２においては、単独で塩酸を用いた比較実験を示している。 The solution of the present invention is as described above, and will be specifically described below based on examples. However, these examples are shown as an aid for easily understanding the present invention, and are not intended to limit the present invention. Further, in order to show the superiority of the production method, in Example 2, a comparative experiment using hydrochloric acid alone is shown.
式； M g ３ A l ( O H )８( C O ３ 2-) 0 . 5 ・２ H ２ Oで示される市販のハイドロタルサイト（ Ｄ Ｈ Ｔ - ６ 、協和化学工業株式会社製。平均粒径約0 . 5〜 1μ ｍ ） を２ ０ ｍ ｇ とり、それに、濃度0 . 0 0 5規定の塩酸濃度でかつ、塩化ナトリウム濃度を1 3 . 3重量％ に調整した水溶液１ ０ ｍ ｌ 加えて、２ ５ ℃ で１ ５ 秒から２ ４ 時間放置した。その後、窒素気流中、0 . 2ミクロンのメンブランフィルターでろ過し、煮沸により脱炭酸ガスを行った蒸留水で、沈殿物を充分に洗浄した。ろ別した沈殿物をかき集め、直ちに減圧し、真空下で１ 時間以上、乾燥して、白色粉末を得た。
Formula : Mg 3 Al (OH) 8 (CO 3 2− ) 0.5 · 2 H 2 O Commercially available hydrotalcite (D H T-6, manufactured by Kyowa Chemical Industry Co., Ltd. Average particle size about 0.. 5 to 1 [mu] m) was taken 2 0 m g, and the concentration 0.0 0 5 and a hydrochloric acid concentration defined, the sodium chloride concentration 1 3.3 solution 1 was adjusted to a weight% in
これを赤外線分光分析、粉末Ｘ線解析、元素分析（ＣＨＮ分析など）、熱分析などの方法により分析した。その結果、赤外スペクトルは、１３６８ｃｍ-1の炭酸イオンのＣ-Ｏ
伸縮振動による吸収が、わずかな残留を残すのみとなった。さらに、炭酸イオンのＣ-O変角振動による６６８ｃｍ-1付近の消失し、６２７ｃｍ-1付近の吸収があらわれた。また、水と炭酸イオンとの相互作用によるとされている３０００ｃｍ-1付近のブロードなピークも消失していた（図１）。食塩、塩酸単独では、ほとんど、脱炭酸イオンが起こっていなかった（図１）。
This was analyzed by methods such as infrared spectroscopic analysis, powder X-ray analysis, elemental analysis (CHN analysis, etc.), thermal analysis and the like. As a result, the infrared spectrum is 1368 cm −1 carbonate C—O
Absorption due to stretching vibration left only a slight residue. Further, disappearance in the vicinity of 668 cm −1 due to carbon dioxide O—O bending vibration and absorption near 627 cm −1 appeared. In addition, a broad peak near 3000 cm −1, which was attributed to the interaction between water and carbonate ions, was also lost (FIG. 1). Almost no decarboxylation occurred with sodium chloride and hydrochloric acid alone (FIG. 1).
また、粉末Ｘ線回折（ＰＸＲＤ）では、００１反射の鋭いピークが観察され、層間隔が、0.780ｎｍから0.797ｎｍに変化したことが分かった。この底面間隔の値は、既に報告されているＣｌイオンを包接することによるマグネシウム・アルミニウム層状複水酸化物の底面間隔の変化の値とよく一致している。得られた、化合物の重量は、ろ過等の操作による重量減やイオン交換による分子量の変化を考慮すると、定量的に回収できたことがわかった。ＣＨＮ分析では、含有するＣの重量％は、0.3％以下であり、出発物であるＤＨＴ-６では、2.3％であるため、かなりの脱炭酸イオンが生じていた。生成物の塩素イオンの
分析値は、11重量％であり、理論値の11.5重量％にほぼ、一致しており、層間に塩素イオンが確かに包接されていることを示している。また、走査型電子顕微鏡で得られた像においても、その粒径や外形に変化の無い生成物であることが確認された（図２-1、
図２-2）。
Further, in powder X-ray diffraction (PXRD), a sharp peak of 001 reflection was observed, and it was found that the layer spacing was changed from 0.780 nm to 0.797 nm. This value of the bottom surface spacing is in good agreement with the value of the change in the bottom surface spacing of the magnesium / aluminum layered double hydroxide by the inclusion of Cl ions already reported. It was found that the weight of the obtained compound could be recovered quantitatively in consideration of weight loss due to operations such as filtration and changes in molecular weight due to ion exchange. In the CHN analysis, the weight% of C contained was 0.3% or less, and in the starting material DHT-6, it was 2.3%, so that considerable decarboxylation ions were generated. The analysis value of chlorine ions in the product is 11% by weight, which is almost coincident with the theoretical value of 11.5% by weight, indicating that the chloride ions are surely included between the layers. Also, in the image obtained with a scanning electron microscope, it was confirmed that the product had no change in its particle size and outer shape (Fig. 2-1,
Fig. 2-2).
次に反応時間を調べるため、塩酸−食塩の混合溶液の添加からろ別までの時間を変化させて、赤外分光により脱炭酸イオンの進行度を調べたところ、反応時間が極めて早く、添加からろ別まで、最も短い１５秒の反応によっても２０時間の反応と変わらない同程度の脱炭酸イオンが達成されていることがわかった（図３）。
なお、出発物質の粒径は、比較的、この化合物の粒径としては、大きい部類に属しているため、粒径の小さなものにも充分に適応可能である。
Next, in order to investigate the reaction time, the time from the addition of the hydrochloric acid-salt mixed solution to the filtration was changed, and when the progress of decarboxylation ion was examined by infrared spectroscopy, the reaction time was extremely fast. Until filtration, it was found that even the shortest 15-second reaction achieved the same degree of decarboxylation ion as the 20-hour reaction (FIG. 3).
In addition, since the particle size of the starting material belongs to a relatively large class as the particle size of this compound, it can be sufficiently applied to those having a small particle size.
〔比較例1〕
塩酸のみの効果を調べるため、式；Ｍｇ３Ａｌ（ＯＨ）８（ＣＯ３ ２−）０．５・２Ｈ２Ｏで示される市販のハイドロタルサイト（ＤＨＴ-６ 、協和化学工業株式会社製。粒径平均は約１μｍ）を２０ｍｇとり、それに、０．１〜０ ．００１規定の各種塩酸濃度に調整した水溶液１０ｍｌ加えて、２５℃で２０時間放置した。その後、窒素気流中、０．２ミクロンのメンブレンフィルターでろ過し、煮沸により脱炭酸ガスを行った蒸留水で、沈殿物を充分に洗浄した。ろ別した沈殿物をかき集め、直ちに減圧し、真空下で１時間以上、乾燥して、白色粉末を得た。
( Comparative Example 1)
In order to examine the effect of hydrochloric acid alone, a commercially available hydrotalcite (DHT-6, manufactured by Kyowa Chemical Industry Co., Ltd.) represented by the formula: Mg 3 Al (OH) 8 (CO 3 2− ) 0.5 · 2H 2 O is used. 20 mg of the average particle size is about 1 μm), and 0.1 to 0. 10 ml of an aqueous solution adjusted to various hydrochloric acid concentrations of 001 N was added and left at 25 ° C. for 20 hours. Thereafter, the precipitate was sufficiently washed with distilled water filtered through a 0.2 micron membrane filter in a nitrogen stream and decarboxylated by boiling. The precipitate collected by filtration was collected, immediately depressurized, and dried under vacuum for 1 hour or longer to obtain a white powder.
これを赤外線分光分析、および重量測定により脱炭酸イオンの程度と重量変化・回収率を調べた（図４-1、図４-2）。その結果、０．００８規定以上の塩酸濃度では、５０％以上の炭酸イオンが減少していたが、０．００５規定以下の塩酸濃度では、４０％未満の程度しか炭酸イオンが減少していなかった（図４-1）。
一方、０．００５規定以下の塩酸濃度では、重量減なく、定量的に回収されたが、０．００８規定以上の塩酸濃度では、１０％以上の重量減少が生じ、０．０５規定超の濃度では、ほとんど溶解して回収できなかった（図４-2）。
The extent of decarboxylation, weight change, and recovery rate were examined by infrared spectroscopic analysis and weight measurement (FIGS. 4-1, 4-2). As a result, at a hydrochloric acid concentration of 0.008 N or more, carbonate ions of 50% or more were reduced, but at a hydrochloric acid concentration of 0.005 N or less, carbonate ions were reduced only to a degree of less than 40%. (Figure 4-1).
On the other hand, at a hydrochloric acid concentration of 0.005 N or less, it was quantitatively recovered without weight reduction, but at a hydrochloric acid concentration of 0.008 N or more, a weight reduction of 10% or more occurred, and a concentration of more than 0.05 N Then, it was hardly dissolved and could not be recovered (Fig. 4-2).
〔実施例２〕
塩添加の効果を調べるため、式；Ｍｇ３Ａｌ（ＯＨ）８（ＣＯ３ ２−）０．５・２Ｈ２Ｏで示される市販のハイドロタルサイト（ＤＨＴ-６，協和化学工業株式会社製。粒径平均は約０．５〜１μｍ）を２０ｍｇとり、それに、０．００５及び０ ．００２５Ｎの２つの塩酸濃度で、かつ、各種の塩化ナトリウム濃度に調整した水溶液を１０ｍｌ加えて、２５℃で２０時間放置した。各々の試料を、その後、窒素気流中、０．２ミクロンのメンブランフィルターでろ過し、煮沸により脱炭酸ガスを行った蒸留水で、沈殿物を充分に洗浄した。ろ別した沈殿物をかき集め、直ちに減圧し、真空下で１時間以上、乾燥して、白色粉末を得た。
[Example 2 ]
In order to investigate the effect of salt addition, a commercially available hydrotalcite (DHT-6, manufactured by Kyowa Chemical Industry Co., Ltd.) represented by the formula: Mg 3 Al (OH) 8 (CO 3 2− ) 0.5 · 2H 2 O 20 mg of the average particle size is about 0.5-1 μm, and 0.005 and 0. 10 ml of an aqueous solution adjusted to two hydrochloric acid concentrations of 0025N and various sodium chloride concentrations were added and left at 25 ° C. for 20 hours. Each sample was then filtered through a 0.2 micron membrane filter in a nitrogen stream, and the precipitate was thoroughly washed with distilled water subjected to decarbonation by boiling. The precipitate collected by filtration was collected, immediately depressurized, and dried under vacuum for 1 hour or longer to obtain a white powder.
これを赤外線分光分析、および重量測定により脱炭酸イオンの程度と重量変化・回収率を調べた（ 図５ ） 。その結果、０ ． ０ ０ ５ 及び０ ． ０ ０ ２ ５規定の２つの塩酸濃度において、食塩添加すなわち塩素イオン添加による顕著な効果が観察され、例えば、０ ． ０ ０ ２ ５規定 の濃度の塩酸では、炭酸イオンは２ ０ ％ 程度しか減少しないが、２ ５ 重量％ 程度までの食塩濃度に調整すると、９ ０ ％ 位の顕著な減少が観察された。これらのいずれの試料においても、回収率は、ほぼ１ ０ ０ ％ であった。
This was examined by infrared spectroscopic analysis and gravimetric measurement for the degree of decarboxylation ion, change in weight and recovery (FIG. 5). As a result, 0. 0 0 5 and 0. In 0 0 2 5 Two hydrochloric defined concentration, remarkable effect of salt addition i.e. chloride ion addition is observed, for example, 0. With hydrochloric acid having a concentration of 0 25 25 N , carbonate ions decreased only by about 20%, but when the salt concentration was adjusted to about 25% by weight, a remarkable decrease of about 90% was observed. In any of these samples, the recovery rate was approximately 100%.
〔実施例３〕
塩酸−食塩の混合溶液による処理で得られた塩素イオンを含む層状複水酸化物のイオン交換能を調べるため、式；Ｍｇ３Ａｌ（ＯＨ）８（ＣＯ３ ２−）０．５・２Ｈ２Ｏで示される市販のハイドロタルサイト（ＤＨＴ-６ 、協和化学工業株式会社製。粒径平均は約０．５〜１μｍ）を２０ｍｇとり、それに、０．００５規定の塩酸濃度で、かつ、１３重量％ の塩化ナトリウム濃度に調整した食塩水溶液を１０ｍｌ加えて、２５℃で２０時間放置した。各々の試料を、その後、窒素気流中、０.２ミクロンのメンブレンフィルターでろ過し、煮沸により脱炭酸ガスを行った蒸留水で、沈殿物を充分に洗浄した。ろ別した沈殿物をかき集め、直ちに減圧し、真空下で１時間以上、乾燥して、白色粉末を得た。これを再度、硫酸ナトリウム、及び炭酸ナトリウムを２種類の水溶液１０ｍｌに、投入し、２５℃で２０時間放置した。各々の試料を、その後、窒素気流中、０．２ミクロンのメンブレンフィルターでろ過し、煮沸により脱炭酸ガスを行った蒸留水で、沈殿物を充分に洗浄した。ろ別した沈殿物をかき集め、直ちに減圧し、真空下で１時間以上、乾燥して、白色粉末を得た。
[Example 3 ]
In order to investigate the ion exchange ability of the layered double hydroxide containing chlorine ions obtained by the treatment with the hydrochloric acid-salt mixed solution, the formula: Mg 3 Al (OH) 8 (CO 3 2− ) 0.5 ·
これを赤外線分光分析、および重量測定により脱炭酸イオンの程度と重量変化・回収率を調べた。その結果、各々、硫酸イオン、炭酸イオンを含む層状複水酸化物に変換されていた。その赤外吸収スペクトル図６に示す。 This was examined by infrared spectroscopic analysis and gravimetric measurement for the degree of decarboxylated ions, weight change and recovery rate. As a result, each was converted into a layered double hydroxide containing sulfate ions and carbonate ions. Its infrared absorption spectrum is shown in FIG.
以上の結果、脱炭酸イオンの作用は低いが、ハイドロタルサイトの粒径や外形、均一性が変化しない程度の希薄な塩酸を用い、その系に中性の塩酸塩（たとえば、塩化ナトリウムなど）を添加し、室温で作用させることにより、脱炭酸イオンが著しく促進され、外形・粒径・重量を保ったまま、極めて短時間で脱炭酸イオンが行われ、添加した陰イオンを
含む層状複水酸化物に変換することが明らかになった。当該方法によって得られた陰イオンを含む層状複水酸化物は、さらに、簡単な通常のイオン交換で、他の陰イオンを含む層状複水酸化物に外形・粒径・重量を保ったまま、さらに変換することが明らかとなった。
As a result, the action of decarboxylation ions is low, but dilute hydrochloric acid that does not change the particle size, shape, and uniformity of hydrotalcite is used, and neutral hydrochloride (for example, sodium chloride) is used in the system. Is added and allowed to act at room temperature, decarboxylation ions are remarkably accelerated, and decarboxylation ions are carried out in a very short time while maintaining the external shape, particle size and weight, and the layered double water containing the added anions It became clear to convert to oxide. The layered double hydroxide containing anions obtained by the method is further subjected to simple ordinary ion exchange while maintaining the outer shape, particle size and weight of the layered double hydroxide containing other anions. It became clear that further conversion was necessary.
以下、塩酸−食塩の混合水溶液の作用による脱炭酸イオン反応について、実施例から推定されるメカニズムを記載し、補足的に説明する。
ハイドロタルサイトなどのような、炭酸イオンを層間に含む層状複水酸化物は、酸性水溶液に投入すると、その層間の炭酸イオン(CO3 2-)が、プロトンと結びつき、−１価の炭
酸水素イオン(HCO3 -)に変化し、それと同時に、電荷のバランスのため塩素イオン(Cl-)を等量、層間に包接する。この炭酸水素イオンは炭酸イオンと異なり、−１価であるため、層状複水酸化物の陽イオン性の層との結びつきが弱くなり、イオン交換しやすくなるものと考えられる。そのため、水溶液中に大量の陰イオン種があると、そのイオン種とイオン交換を起こす。
Hereinafter, the mechanism presumed from an Example is described and supplementarily demonstrated about the decarboxylation ion reaction by the effect | action of the aqueous solution of hydrochloric acid-salt.
When a layered double hydroxide such as hydrotalcite containing carbonate ions between layers is put into an acidic aqueous solution, the carbonate ions (CO 3 2- ) between the layers combine with protons, and −1 valent hydrogen carbonate changes to, at the same time, chlorine ions for charge balance - ions (HCO 3) - clathrating equal amounts, the interlayer (Cl). This carbonate ion is different from carbonate ion and is −1 valent. Therefore, it is considered that the bond between the layered double hydroxide and the cationic layer becomes weak and ion exchange is facilitated. Therefore, if there is a large amount of anionic species in the aqueous solution, ion exchange occurs with the ionic species.
さらに、酸濃度を増していくと、さらに１価の炭酸水素イオン(HCO3 -)は、中性のH2CO3に変化し、層間より液相に脱離していく。このとき、やはり、水溶液中に大量の陰イオン種があると、そのイオン種を取り込む。この様にして、脱炭酸イオンと液相中の陰イオンの取り込みが行われる。層状複水酸化物の金属水酸化物層は、本来は酸に侵されるものであるが、層間の炭酸イオンの方が酸のプロトンと反応しやすいため、その反応が優位に起こり、粒径・外形・重量が減少しないのであろう。しかし、酸濃度が増してくると、酸が層状複水酸化物の金属水酸化物層を、侵すようになり、徐々に溶解を起こし、ついには構造が変化して、溶解してしまうと考えられる。以上のように、当該製造方法は、酸の炭酸イオンに対する反応が、層状複水酸化物の金属水酸化物層への反応よりも、優先されることを利用したものである。 Furthermore, as the acid concentration increases, monovalent hydrogen carbonate ions (HCO 3 − ) change to neutral H 2 CO 3 and are desorbed from the interlayer into the liquid phase. At this time, if there is a large amount of anionic species in the aqueous solution, the ionic species are taken up. In this way, decarboxylation ions and anions in the liquid phase are taken up. The metal hydroxide layer of a layered double hydroxide is originally attacked by an acid, but since the carbonate ions between the layers are more likely to react with the protons of the acid, the reaction takes place predominantly, and the particle size / The outer shape and weight will not decrease. However, as the acid concentration increases, the acid begins to attack the metal hydroxide layer of the layered double hydroxide, causing gradual dissolution, eventually changing the structure and dissolving. It is done. As described above, the production method utilizes the fact that the reaction of the acid to the carbonate ion is prioritized over the reaction of the layered double hydroxide to the metal hydroxide layer.
この機構は、単に塩酸は濃度のみならず、その使用する容量も重要であることを示している。すなわち、出発物の層状複酸化物中の炭酸イオンを炭酸水素イオンさらには、脱離させる以上のプロトン量、すなわち塩酸溶液量を用いると、酸濃度が増すのと同じ効果を及ぼし、過剰のプロトンが層状複水酸化物の金属水酸化物層を侵し、溶解を起こすと考えられる。実際、ハイドロタルサイト（ Ｄ Ｈ Ｔ − ６ ， 協和化学工業株式会社製。粒径平均は約0 . 5〜 １ μ ｍ ） を２ ０ ｍ ｇ に対し、0.005規定の塩酸濃度の溶液の量を変化させて、その重量変化を調べたところ、１ ５ ｍ ｌ 以上の量では顕著に重量減少が見られた。また、炭酸イオンの減少は、同じように１ ５ ｍ ｌ を超える塩酸量で顕著であった。この時、プロトン量は炭酸塩量の約2 . 2倍（ モル比） であるが、これは、炭酸イオンが、中性の炭酸ガスになる量であり、おおむね、以上に述べた機構と一致している。
このことは、モル数で、層状複水酸化物の炭酸イオン量と水溶液中のプロトン量が１ ： １ 〜 ２ という量にして、さらに、塩素イオンを添加することによって、炭酸水素イオンのイオン交換を促進させるのが、重量減少がなく脱炭酸が起こる条件であるといえる。
以上のように、当該製造方法は、炭酸イオンとプロトン量の比の制御と炭酸水素イオンのイオン交換を利用して、金属水酸化物層への反応を最小限に留めながら、最も効率的に脱炭酸イオンを行おうとする方法であり、実際の適応に関しては、以上のようなイオン種の量を考慮して、最適な条件にする必要がある。
This mechanism shows that not only the concentration of hydrochloric acid is important, but also the capacity used. In other words, using carbonate ions in the starting layered double oxide, hydrogen carbonate ions, and protons more than desorbing, ie, hydrochloric acid solution, have the same effect as increasing the acid concentration, and excess protons. It is considered that the metal hydroxide layer of the layered double hydroxide causes the dissolution. Indeed, hydrotalcite (D H T -.. 6 , manufactured by Kyowa Chemical Industry Co., Ltd. average grain diameter is about 0 5~ 1 μ m) to a 2 0 m g, the amount of a solution of hydrochloric acid concentration of 0.005 provisions When the change in weight was examined by changing the weight, a significant decrease in weight was observed at an amount of 15 ml or more. In addition, the decrease of carbonate ion was also remarkable at the amount of hydrochloric acid exceeding 15 ml. At this time, the proton amount is about 2.2 times the molar amount of the carbonate (molar ratio). This is the amount of carbonate ion that turns into neutral carbon dioxide, which is roughly the same as the mechanism described above. I'm doing it.
This means that the amount of carbonate ions of the layered double hydroxide and the amount of protons in the aqueous solution is 1: 1 to 2 in terms of moles, and further, by adding chlorine ions, ion exchange of bicarbonate ions. It can be said that it is a condition that decarboxylation occurs without weight reduction.
As described above, the production method is most efficient while controlling the ratio of carbonate ions and protons and ion exchange of hydrogen carbonate ions while minimizing the reaction to the metal hydroxide layer. This is a method for decarboxylation, and it is necessary to set the optimum conditions in consideration of the amount of ionic species as described above for actual adaptation.
本発明は、発明の効果の欄でも触れたように、その意義は格別のものがある。すなわち、本発明は、従来容易には得られなかった陰イオン交換性の層状複水酸化物を、短時間に簡単に得ることができる。そして得られる易陰イオン交換性の層状複水酸化物は、それ自体産業上利用しうるもので、その意義は大きい。加えて、その生成物の陰イオン交換性から、今後各種分野に大いに利用されることが期待される。例えば、陰イオン性機能性有機分子をイオン交換プロセスといった極めて簡単な操作によるいわゆるソフトケミカル的な反応によって合成し、提供することができるため、新規な機能を有してなる新規物質開発・促進につながるものと期待される。 As described in the column of the effect of the invention, the significance of the present invention is exceptional. That is, according to the present invention, an anion-exchangeable layered double hydroxide that has not been easily obtained can be easily obtained in a short time. The resulting easily anion-exchangeable layered double hydroxide can be used industrially and has great significance. In addition, the product is expected to be used in various fields in the future due to the anion exchange property of the product. For example, anionic functional organic molecules can be synthesized and provided by a so-called soft chemical reaction by an extremely simple operation such as an ion exchange process, so that new substances having new functions can be developed and promoted. Expected to be connected.
出発原料となる炭酸イオンを含むハイドロタルサイトなどの層状複水酸化物は、アスペクト比の高い平板状の結晶として析出し、結晶のｃ軸方向が平板と垂直な方向になる。イオン交換によって外形・粒径が変化しないから、出発物として、粒径制御が容易で、結晶のアスペクト比の高い、炭酸イオン含有層状複水酸化物を使用できるため、粒径が制御された有機無機複合体を合成することが可能となり、特定の方向に並んだ配向膜の形成への道が開ける。これにより、基板上への規則正しい配向性をもった累積によるナノデバイスの構築といった新しい応用分野にまで発展し、及ぶことが考えられる。 A layered double hydroxide such as hydrotalcite containing carbonate ions as a starting material precipitates as a flat crystal having a high aspect ratio, and the c-axis direction of the crystal is perpendicular to the flat plate. Since the outer shape and particle size do not change due to ion exchange, it is easy to control the particle size as a starting material, and a carbonate ion-containing layered double hydroxide with a high crystal aspect ratio can be used. It becomes possible to synthesize inorganic composites, opening the way to the formation of alignment films arranged in a specific direction. As a result, it can be considered that it will develop and extend to new application fields such as the construction of nanodevices by accumulation with regular orientation on the substrate.
Claims (6)
MxN (OH) z (CO 3 2− ) to 0.5 · nH 2 O (wherein x represents a numerical range of 1.8 ≦ x ≦ 4.2. Z represents 2 (x + 1) M is a divalent metal ion, N is a trivalent metal ion, and n varies depending on the humidity of the environment, but has a composition represented by 2). A layered double hydroxide containing carbonate ions having a similar structure is contacted with a mixed aqueous solution containing a salt of a protic acid and an anion (X) to perform anion exchange. An anion is eluted in an aqueous solution, and an anion (X) is introduced into a carbonate ion site in the eluted layered double hydroxide to produce a layered double hydroxide rich in anion exchange. A method for producing an ion-exchange layered double hydroxide.
The anion exchange property according to claim 1 or 3, wherein the concentration of the protic acid in the aqueous solution is 0.00005 to 0.025 N, and the salt concentration of the anion (X) is 2% by weight or more. method of manufacturing a layered Fukusui oxide.
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| WO2012102150A1 (en) | 2011-01-27 | 2012-08-02 | 独立行政法人物質・材料研究機構 | Water-swelling layered double hydroxide, method for producing same, gel or sol substance, double hydroxide nanosheet, and method for producing same |
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| CN101472843A (en) * | 2006-04-20 | 2009-07-01 | 水泽化学工业株式会社 | Novel aluminum complex hydroxide salt and method for producing the same |
| PL2055675T3 (en) | 2006-07-31 | 2016-03-31 | Japan Dev & Construction | Hydrotalcite-like particulate material and method for production thereof |
| JP5317293B2 (en) * | 2007-12-05 | 2013-10-16 | 独立行政法人物質・材料研究機構 | Method for producing anion-exchange layered double hydroxide |
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| WO2012102150A1 (en) | 2011-01-27 | 2012-08-02 | 独立行政法人物質・材料研究機構 | Water-swelling layered double hydroxide, method for producing same, gel or sol substance, double hydroxide nanosheet, and method for producing same |
| US9545615B2 (en) | 2011-01-27 | 2017-01-17 | National Institute For Materials Science | Water-swelling layered double hydroxide, method for producing same, gel or sol substance, double hydroxide nanosheet, and method for producing same |
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