JP5568726B2 - Titanium oxide / layered double hydroxide composite and method for producing the same - Google Patents
Titanium oxide / layered double hydroxide composite and method for producing the same Download PDFInfo
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- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 title claims description 166
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 title claims description 115
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 title claims description 104
- 239000002131 composite material Substances 0.000 title claims description 43
- 238000004519 manufacturing process Methods 0.000 title claims description 9
- 238000000034 method Methods 0.000 claims description 42
- 239000007787 solid Substances 0.000 claims description 30
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 24
- 238000009830 intercalation Methods 0.000 claims description 23
- 230000002687 intercalation Effects 0.000 claims description 22
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- 150000001875 compounds Chemical class 0.000 claims description 18
- 238000010438 heat treatment Methods 0.000 claims description 18
- 238000001179 sorption measurement Methods 0.000 claims description 12
- 239000013078 crystal Substances 0.000 claims description 11
- 238000006114 decarboxylation reaction Methods 0.000 claims description 11
- 229910003023 Mg-Al Inorganic materials 0.000 claims description 10
- LLZRNZOLAXHGLL-UHFFFAOYSA-J titanic acid Chemical compound O[Ti](O)(O)O LLZRNZOLAXHGLL-UHFFFAOYSA-J 0.000 claims description 10
- 238000010304 firing Methods 0.000 claims description 9
- 150000004679 hydroxides Chemical class 0.000 claims description 9
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 4
- GDVKFRBCXAPAQJ-UHFFFAOYSA-A dialuminum;hexamagnesium;carbonate;hexadecahydroxide Chemical group [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 claims description 3
- 229910001701 hydrotalcite Inorganic materials 0.000 claims description 3
- 229960001545 hydrotalcite Drugs 0.000 claims description 3
- 229910001873 dinitrogen Inorganic materials 0.000 claims description 2
- 238000012545 processing Methods 0.000 claims description 2
- 239000004408 titanium dioxide Substances 0.000 claims 1
- 239000000243 solution Substances 0.000 description 70
- 239000010410 layer Substances 0.000 description 42
- 239000000843 powder Substances 0.000 description 35
- 239000011148 porous material Substances 0.000 description 23
- 230000000052 comparative effect Effects 0.000 description 17
- 239000002994 raw material Substances 0.000 description 16
- 239000000126 substance Substances 0.000 description 16
- IKHGUXGNUITLKF-UHFFFAOYSA-N Acetaldehyde Chemical compound CC=O IKHGUXGNUITLKF-UHFFFAOYSA-N 0.000 description 14
- 238000002441 X-ray diffraction Methods 0.000 description 13
- 239000007858 starting material Substances 0.000 description 11
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 11
- 239000004927 clay Substances 0.000 description 10
- -1 Cl − Chemical class 0.000 description 9
- 150000001450 anions Chemical class 0.000 description 9
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- 239000000725 suspension Substances 0.000 description 8
- 239000010936 titanium Substances 0.000 description 8
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- 238000009826 distribution Methods 0.000 description 7
- 239000007789 gas Substances 0.000 description 7
- 239000011229 interlayer Substances 0.000 description 7
- 239000000463 material Substances 0.000 description 7
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- 239000010419 fine particle Substances 0.000 description 6
- 239000003463 adsorbent Substances 0.000 description 5
- 230000005260 alpha ray Effects 0.000 description 5
- BVKZGUZCCUSVTD-UHFFFAOYSA-N carbonic acid Chemical compound OC(O)=O BVKZGUZCCUSVTD-UHFFFAOYSA-N 0.000 description 5
- 150000002500 ions Chemical class 0.000 description 5
- 230000001699 photocatalysis Effects 0.000 description 5
- 238000002360 preparation method Methods 0.000 description 5
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- 125000001309 chloro group Chemical group Cl* 0.000 description 4
- 238000001035 drying Methods 0.000 description 4
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- 229910021645 metal ion Inorganic materials 0.000 description 4
- 238000003756 stirring Methods 0.000 description 4
- 238000006467 substitution reaction Methods 0.000 description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- 239000003513 alkali Substances 0.000 description 3
- 238000005349 anion exchange Methods 0.000 description 3
- 125000000129 anionic group Chemical group 0.000 description 3
- 239000003054 catalyst Substances 0.000 description 3
- 239000000499 gel Substances 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 238000002429 nitrogen sorption measurement Methods 0.000 description 3
- 229920002620 polyvinyl fluoride Polymers 0.000 description 3
- 238000000926 separation method Methods 0.000 description 3
- 150000003608 titanium Chemical class 0.000 description 3
- 229910052719 titanium Inorganic materials 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 208000005156 Dehydration Diseases 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 description 2
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Natural products OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 2
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 2
- 229910021529 ammonia Inorganic materials 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
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- 229910052742 iron Inorganic materials 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000004570 mortar (masonry) Substances 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- BBJSDUUHGVDNKL-UHFFFAOYSA-J oxalate;titanium(4+) Chemical compound [Ti+4].[O-]C(=O)C([O-])=O.[O-]C(=O)C([O-])=O BBJSDUUHGVDNKL-UHFFFAOYSA-J 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- SOQBVABWOPYFQZ-UHFFFAOYSA-N oxygen(2-);titanium(4+) Chemical class [O-2].[O-2].[Ti+4] SOQBVABWOPYFQZ-UHFFFAOYSA-N 0.000 description 2
- DCKVFVYPWDKYDN-UHFFFAOYSA-L oxygen(2-);titanium(4+);sulfate Chemical compound [O-2].[Ti+4].[O-]S([O-])(=O)=O DCKVFVYPWDKYDN-UHFFFAOYSA-L 0.000 description 2
- 238000013032 photocatalytic reaction Methods 0.000 description 2
- 231100000719 pollutant Toxicity 0.000 description 2
- 229920000447 polyanionic polymer Polymers 0.000 description 2
- 235000011121 sodium hydroxide Nutrition 0.000 description 2
- 238000003786 synthesis reaction Methods 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 229910000348 titanium sulfate Inorganic materials 0.000 description 2
- XJDNKRIXUMDJCW-UHFFFAOYSA-J titanium tetrachloride Chemical compound Cl[Ti](Cl)(Cl)Cl XJDNKRIXUMDJCW-UHFFFAOYSA-J 0.000 description 2
- 238000004438 BET method Methods 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- 229910002651 NO3 Inorganic materials 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- VMHLLURERBWHNL-UHFFFAOYSA-M Sodium acetate Chemical compound [Na+].CC([O-])=O VMHLLURERBWHNL-UHFFFAOYSA-M 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 229910021536 Zeolite Inorganic materials 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 150000001732 carboxylic acid derivatives Chemical class 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 238000005341 cation exchange Methods 0.000 description 1
- 125000002091 cationic group Chemical group 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 238000010908 decantation Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
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- 229910052731 fluorine Inorganic materials 0.000 description 1
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- 238000004108 freeze drying Methods 0.000 description 1
- 238000000265 homogenisation Methods 0.000 description 1
- 238000007602 hot air drying Methods 0.000 description 1
- QOSATHPSBFQAML-UHFFFAOYSA-N hydrogen peroxide;hydrate Chemical compound O.OO QOSATHPSBFQAML-UHFFFAOYSA-N 0.000 description 1
- 229910052740 iodine Inorganic materials 0.000 description 1
- 239000011630 iodine Substances 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 229910052748 manganese Inorganic materials 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910000000 metal hydroxide Inorganic materials 0.000 description 1
- 150000004692 metal hydroxides Chemical class 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
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- 229910001725 motukoreaite Inorganic materials 0.000 description 1
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- 235000006408 oxalic acid Nutrition 0.000 description 1
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- 239000000741 silica gel Substances 0.000 description 1
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- 239000001632 sodium acetate Substances 0.000 description 1
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- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
Description
本発明は、酸化チタン／層状複水酸化物複合体及びその製造方法に関する。 The present invention relates to a titanium oxide / layered double hydroxide composite and a method for producing the same.
シリカゲルやゼオライトや活性炭等、多孔体材料は、吸着剤、分離材料、触媒材料、触媒担体等に広く応用されている。それら多孔体の中でも、酸化チタン／粘土複合多孔体は、板状の層が間隔を空けて並びスリット状の細孔構造を形成し、さらにそのスリット状の層間に酸化チタン微粒子を包含するというユニークな構造を有しており、注目を集めている。 Porous materials such as silica gel, zeolite and activated carbon are widely applied to adsorbents, separation materials, catalyst materials, catalyst carriers and the like. Among these porous bodies, titanium oxide / clay composite porous bodies are unique in that plate-like layers are arranged at intervals to form a slit-like pore structure, and titanium oxide fine particles are included between the slit-like layers. It has a remarkable structure and is attracting attention.
酸化チタン／粘土複合多孔体は、粘土の平板結晶層の層間にナノサイズの酸化チタン微粒子が挿入された材料であり、粘土結晶層の内部表面が外部空間に通じている多孔体構造をとるため、大きな比表面積を有しており、高い吸着性能を示す（例えば特許文献１〜６参照）。このため、吸着材と触媒とを併せ持った機能性材料となり、室内空気中に含まれているホルマリン等の有害な有機物の吸着分解処理や、水中の汚染物質の処理等への利用が検討されている。 Titanium oxide / clay composite porous material is a material in which nano-sized titanium oxide fine particles are inserted between clay flat crystal layers, and has a porous structure in which the inner surface of the clay crystal layer leads to the external space. It has a large specific surface area and exhibits high adsorption performance (see, for example, Patent Documents 1 to 6). For this reason, it becomes a functional material that has both an adsorbent and a catalyst, and its use in the adsorption and decomposition treatment of harmful organic substances such as formalin contained in indoor air and the treatment of pollutants in water has been studied. Yes.
例えば、特許文献１〜６に示されているような酸化チタン／粘土複合多孔体では、トルエンのような疎水性物質には酸化チタンと比較して高い吸着性を示す。しかしながら、エタノールのような親水性物質の吸着性は酸化チタンと大きな差はなく（非特許文献１及び２）、親水性物質を吸着する吸着材としての能力は低いものであった。 For example, in the titanium oxide / clay composite porous body as shown in Patent Documents 1 to 6, a hydrophobic substance such as toluene exhibits higher adsorptivity than titanium oxide. However, the adsorptivity of a hydrophilic substance such as ethanol is not significantly different from that of titanium oxide (Non-patent Documents 1 and 2), and the ability as an adsorbent for adsorbing a hydrophilic substance is low.
本発明は、上記従来の実情に鑑みてなされたものであり、親水性物質の吸着能力に優れた酸化チタン／層状複水酸化物複合体を提供することを解決すべき課題としている。 The present invention has been made in view of the above-described conventional situation, and an object to be solved is to provide a titanium oxide / layered double hydroxide composite having excellent hydrophilic substance adsorption ability.
本発明者らは、上記従来の酸化チタン／粘土複合多孔体について、エタノールのような親水性物質の吸着性が低い理由について鋭意研究を行なった。その結果、特許文献１〜６に示されているような酸化チタン／粘土複合多孔体は、スメクタイト類を始めとするカチオン交換性の膨潤性粘土を使用しており、その細孔内が疎水性であるということに起因するのではないかと推定した。 The inventors of the present invention conducted intensive research on the reason why the conventional titanium oxide / clay composite porous body has a low adsorptivity for hydrophilic substances such as ethanol. As a result, the titanium oxide / clay composite porous body as shown in Patent Documents 1 to 6 uses a cation-exchangeable swelling clay such as smectites, and the pores are hydrophobic. It was presumed that this was due to the fact that
そして、さらに本発明者らは、カチオン交換性の膨潤性粘土と異なり、アニオン交換性を有する層状複水酸化物（LDH: Layered Double Hydroxide、ハイドロタルサイト様化合物とも呼ばれる）に注目した。なぜならば、層状複水酸化物は、水和性の高い金属水酸化物あるいは酸化物を多く含有しているため、親水性の層間表面を有しており、より表面親水性の高い酸化チタン／粘土複合多孔体となると期待できるからである。そして、鋭意研究を重ねた結果、本発明を完成するに至った。 Further, the present inventors paid attention to a layered double hydroxide (also referred to as LDH: Layered Double Hydroxide, also called a hydrotalcite-like compound) having an anion exchange property, unlike the cation exchange swellable clay. This is because the layered double hydroxide contains a highly hydratable metal hydroxide or oxide, and therefore has a hydrophilic interlayer surface. This is because it can be expected to be a clay composite porous body. As a result of intensive studies, the present invention has been completed.
すなわち、本発明の酸化チタン／層状複水酸化物複合体は、層状複水酸化物の層間に酸化チタンが挿入されていることを特徴とする。 That is, the titanium oxide / layered double hydroxide composite of the present invention is characterized in that titanium oxide is inserted between the layers of the layered double hydroxide.
本発明の酸化チタン／層状複水酸化物複合体では、酸化チタンと複合させる粘土化合物として層状複水酸化物を用いる。この層状複水酸化物は、インターカレーションによって層間に様々なアニオン種を挿入することができる。例えばペルオキソチタン溶液のようにチタンを含むアニオン種を含んだ溶液と層状複水酸化物とを接触させることによってインターカレーションを行なった後、加熱等の脱水処理を行なうことによって、層間に容易に酸化チタンを挿入することができる。こうして、酸化チタンが層間に挿入された酸化チタン／層状複水酸化物複合体は、層間距離が広がり、多孔性が大きくなり、このため比表面積も増大して、吸着量が増大する。しかも、層間内部の細孔表面は親水性であるため、親水性物質が容易に侵入することができ、親水性物質の吸着量が大きなものとなる。さらには、光照射した場合、層間内に吸着された物質が、層間内部に挿入された酸化チタンの光触媒機能により、光酸化分解されることが期待される。 In the titanium oxide / layered double hydroxide composite of the present invention, a layered double hydroxide is used as a clay compound to be combined with titanium oxide. In this layered double hydroxide, various anionic species can be inserted between the layers by intercalation. For example, intercalation is performed by bringing a solution containing an anionic species containing titanium into contact with a layered double hydroxide, such as a peroxotitanium solution, and then dehydration treatment such as heating is performed. Titanium oxide can be inserted. Thus, the titanium oxide / layered double hydroxide composite in which titanium oxide is inserted between the layers increases the distance between layers and increases the porosity, thereby increasing the specific surface area and increasing the amount of adsorption. In addition, since the surface of the pores inside the interlayer is hydrophilic, the hydrophilic substance can easily enter, and the amount of adsorption of the hydrophilic substance becomes large. Furthermore, when light is irradiated, the substance adsorbed in the interlayer is expected to be photooxidatively decomposed by the photocatalytic function of titanium oxide inserted in the interlayer.
本発明において用いられる層状複水酸化物（Layered Double Hydroxide）とは、下記のように表される一般式をもつ不定比化合物をいう。 The layered double hydroxide used in the present invention refers to a non-stoichiometric compound having a general formula represented as follows.
ここで，M2+はMg，Mn，Fe，Co，Ni，Cu，Znなどの二価金属イオンを示し、M3+はAl，Cr，Fe，Co，Inなどの三価金属イオンを示し、Aはn価のアニオンを示す。左側括弧部分は、層状構造の骨格をなす部分であり、二価金属イオンの一部を三価金属イオンが置換（固溶）することによって正電荷を有しており、その電荷を補うために中間層へ陰イオンを取り込んで電気的中性を保つ構造となっている。また、中間層の残りの空間は親水性が高いため、通常、乾燥条件に応じた量の水分子を含んでいる。この中間層の陰イオンはCl-，NO3 -，CO3 2-，カルボン酸などのn価の陰イオンであり、アニオン交換が可能とされている。 Here, M 2+ represents a divalent metal ion such as Mg, Mn, Fe, Co, Ni, Cu, or Zn, and M 3+ represents a trivalent metal ion such as Al, Cr, Fe, Co, or In. , A represents an n-valent anion. The left parenthesis part is the part that forms the skeleton of the layered structure, and has a positive charge by replacing (solid solution) a part of the divalent metal ion with a trivalent metal ion. It has a structure in which negative ions are taken into the intermediate layer to maintain electrical neutrality. Moreover, since the remaining space of the intermediate layer has high hydrophilicity, it usually contains an amount of water molecules according to the drying conditions. The anions in this intermediate layer are n-valent anions such as Cl − , NO 3 − , CO 3 2− , and carboxylic acid, and anion exchange is possible.
このような層状複水酸化物は、天然産のもの（例えばハイドロタルサイト（Hydrotalcite）、マナッセイト（Manasseite）、モツコレアイト（Motukoreaite）、スティッヒタイト（Stichtite）、ショグレナイト（Sjogrenite）、バーバートナイト（Barbertonite）、パイロアウライト（Pyroaurite）、イオマイト（Iomaite）、クロロマガルミナイト（Chlormagaluminite）、ハイドロカルマイト（Hydrocalmite）、グリーン ラスト１（Green Rust1）、ベルチェリン（Berthierine）、タコバイト（Takovite）、リーベサイト（Reevesite）、ホネサイト（Honessite）、イヤードライト（Eardlyite）、メイキセネライト（Meixnerite）等）の他、人工的に合成されたものであってもよい。 Such layered double hydroxides are naturally occurring (eg, Hydrotalcite, Manasseite, Motukoreaite, Stichtite, Sjogrenite, Barbertonite) , Pyroaurite, Iomaite, Chlormagaluminite, Hydrocalmite, Green Rust1, Berthierine, Takovite, Reevesite ), Honesite, Eardlyite, Meixnerite, etc.), or may be artificially synthesized.
これらの層状複水酸化物の中でも、ハイドロタルサイト等のＭｇ−Ａｌ系層状複水酸化物が好ましい。発明者らは、Ｍｇ−Ａｌ系層状複水酸化物の層間に酸化チタンが挿入された複合体は容易に合成することができ、酸化チタンの挿入によって確実に比表面積が大きくなることを確認している。そして、さらには、窒素ガス吸着測定によるＢＥＴ法比表面積を１１０ｍ２／ｇ以上とすることができ、ＭＰ法によるマイクロポア容積を０．０１ｃｍ３／ｇ以上とすることができることを確認している。このような大きな比表面積や微細な細孔は、原料である層状複水酸化物粉体では認められず、層状複水酸化物層間に酸化チタン微粒子を複合化することによって得られる顕著な効果である。 Among these layered double hydroxides, Mg—Al-based layered double hydroxides such as hydrotalcite are preferable. The inventors have confirmed that a composite in which titanium oxide is inserted between layers of Mg—Al-based layered double hydroxide can be easily synthesized, and that the specific surface area is surely increased by the insertion of titanium oxide. ing. Further, it has been confirmed that the BET specific surface area by nitrogen gas adsorption measurement can be 110 m 2 / g or more, and the micropore volume by MP method can be 0.01 cm 3 / g or more. . Such a large specific surface area and fine pores are not recognized in the layered double hydroxide powder as a raw material, but are remarkable effects obtained by combining titanium oxide fine particles between the layered double hydroxide layers. is there.
本発明の酸化チタン／層状複水酸化物複合体の酸化チタン含有量は、１０質量％以上が好ましく、さらに好ましくは３０質量％以上、最も好ましくは４０質量％以上である。酸化チタン／層状複水酸化物複合体の酸化チタン含有量が１０質量％未満では、層状複水酸化物層間の細孔構造が充分に発達せず、インターカレーションによる比表面積の増加も小さく、吸着材としての吸着量が小さくなる。ただし、酸化チタンの含有量が多いと、相対的に層状複水酸化物複合体の含有量が少なくなるため、親水性の発揮が損なわれ、親水性の汚染物質の吸着効果が損なわれ易くなる。このため、酸化チタンの含有量は９０質量％以下が好ましく、さらに好ましくは８０質量％以下、最も好ましくは７０質量％以下である。 The titanium oxide content of the titanium oxide / layered double hydroxide composite of the present invention is preferably 10% by mass or more, more preferably 30% by mass or more, and most preferably 40% by mass or more. When the titanium oxide content of the titanium oxide / layered double hydroxide composite is less than 10% by mass, the pore structure between the layered double hydroxide layers does not sufficiently develop, and the increase in specific surface area due to intercalation is small, The amount of adsorption as an adsorbent is reduced. However, if the content of titanium oxide is large, the content of the layered double hydroxide complex is relatively reduced, so that the hydrophilicity is impaired and the adsorption effect of hydrophilic pollutants is easily impaired. . For this reason, the content of titanium oxide is preferably 90% by mass or less, more preferably 80% by mass or less, and most preferably 70% by mass or less.
また、層状複水酸化物の層間に挿入されている酸化チタンは、その全部又は一部が結晶化していることが好ましく、さらにアナターゼ型結晶構造であることが好ましい。酸化チタンの結晶構造はルチル型、アナターゼ型とブルッカイト型の３種類が知られているが、このうちアナターゼ型結晶構造を有する酸化チタンは多くの光触媒反応で高い反応活性を示している。このため、層状複水酸化物の層間に吸着された親水性の汚染物質を光触媒分解する機能に優れた複合体となる。 The titanium oxide inserted between the layers of the layered double hydroxide is preferably crystallized in whole or in part, and more preferably has an anatase type crystal structure. Three types of crystal structures of titanium oxide are known: rutile type, anatase type and brookite type. Of these, titanium oxide having an anatase type crystal structure shows high reaction activity in many photocatalytic reactions. For this reason, it becomes a composite excellent in the function of photocatalytically decomposing hydrophilic contaminants adsorbed between the layers of the layered double hydroxide.
本発明の酸化チタン／層状複水酸化物複合体は、以下のようにして製造することができる。すなわち、本発明の酸化チタン／層状複水酸化物複合体の製造方法は、層状複水酸化物あるいは加熱焼成により該層状複水酸化物の一部又は全部が酸化物となった化合物と、ｐＨが３以上のペルオキソチタン溶液とを混合することにより、層状複水酸化物の層間に酸化チタンを挿入させて酸化チタン／層状複水酸化物とするインターカレーション工程を有することを特徴とする。 The titanium oxide / layered double hydroxide composite of the present invention can be produced as follows. That is, the method for producing a titanium oxide / layered double hydroxide composite of the present invention comprises a layered double hydroxide or a compound in which a part or all of the layered double hydroxide is converted into an oxide by heating and baking, and a pH. Is characterized by having an intercalation step of mixing titanium oxide with a peroxotitanium solution of 3 or more to form titanium oxide / layered double hydroxide by inserting titanium oxide between layers of the layered double hydroxide.
本発明の酸化チタン／層状複水酸化物複合体の製造方法では、インターカレーション現象を利用したインターカレーション工程を行なう。すなわち、層状複水酸化物とｐＨが３以上のペルオキソチタン溶液とを反応させ、層状複水酸化物の層間に酸化チタンを挿入させて酸化チタン／層状複水酸化物とする。ペルオキソチタン溶液とは、水酸化チタンと過酸化水素水とを混合することにより水酸化チタンのＯＨ−の一部が過酸化状態とされたペルオキソチタンイオンを含有している液体をいう。このようなペルオキソチタン溶液は次のような化学式で示される、二核錯体アニオンＴｉ2Ｏ5（ＯＨ）x (X-2)-（Ｘ＞２）や、そのポリアニオン（（Ｔｉ2Ｏ5）q（ＯＨ）y (y-2q)-（ｑ／ｙ＞２））等を含んでいると考えられている（非特許文献３）。このペルオキソチタン溶液は、金属や酸化物などからも合成することができる。 In the method for producing a titanium oxide / layered double hydroxide composite of the present invention, an intercalation process using an intercalation phenomenon is performed. That is, the layered double hydroxide is reacted with a peroxotitanium solution having a pH of 3 or more, and titanium oxide is inserted between the layers of the layered double hydroxide to form titanium oxide / layered double hydroxide. The peroxotitanium solution refers to a liquid containing peroxotitanium ions in which a part of OH − of titanium hydroxide is in a peroxidized state by mixing titanium hydroxide and hydrogen peroxide solution. Such a peroxotitanium solution is represented by the following chemical formula, such as the binuclear complex anion Ti 2 O 5 (OH) x (X-2) − (X> 2) and its polyanion ((Ti 2 O 5 )). q (OH) y (y-2q)- (q / y> 2)) and the like (non-patent document 3). This peroxotitanium solution can also be synthesized from metals and oxides.
また、「加熱焼成により該層状複水酸化物の一部又は全部が酸化物となった化合物」とは、非特許文献４に記載されているように、水を添加することにより一部でももとの層状複水酸化物へ戻ることのできる状態の化合物をいい、水を添加しても全くもとの層状複水酸化物へ戻ることのできない状態の化合物は含まない。
In addition, “a compound in which part or all of the layered double hydroxide is converted into an oxide by heating and firing” means that a part of the layered double hydroxide is added by adding water as described in
ペルオキソチタン溶液は、非特許文献３によるとｐＨが３から９の領域で、また特許文献７によるとｐＨが３以上の領域で、チタンを含む二核錯体アニオンＴｉ2Ｏ5（ＯＨ）x (X-2)-や、そのポリアニオンといったアニオン種を含有しており、このため、アニオン交換性を有する層状複水酸化物と、容易にアニオン交換をしてペルオキソチタンを層間に侵入させることができる。ペルオキソチタン溶液のｐＨが３未満の酸性領域ではペルオキソチタン種はカチオン種が主であり、本発明への使用には向かない。具体的には、難イオン交換性の炭酸イオンを層間に含まない層状複水酸化物あるいは炭酸イオンを層間に含んでいても炭酸イオンの一部または全部が除去乃至は他のアニオンに置換された層状複水酸化物と、ｐＨが３以上のペルオキソチタン溶液との反応は、両者を単に混合するだけで容易に進行し、酸化チタン／層状複水酸化物複合体が得られる。混合の方法については特に制限はない。混合中の温度は室温でもよいが、インターカレーションを促進させるために、必要に応じて数十℃程度の加温をしてもよい。生成した酸化チタン／層状複水酸化物複合体は、濾過、遠心分離等の適当な方法で固形分を分離することにより採取することができる。こうして得られた層状複水酸化物の層間に侵入したペルオキソチタンは、徐々に酸素を放出して、酸化チタンとなる。あるいは、ここで、挿入工程後に加熱をすることにより、ペルオキソチタンから酸化チタンへの変換を促進させても良い。 According to Non-Patent Document 3, the peroxotitanium solution is a binuclear complex anion Ti 2 O 5 (OH) x ( X-2) -and anionic species such as its polyanion, and therefore, an anion-exchangeable layered double hydroxide and an anion exchange can be easily performed to allow peroxotitanium to penetrate between layers. . In the acidic region where the pH of the peroxotitanium solution is less than 3, the peroxotitanium species are mainly cationic species and are not suitable for use in the present invention. Specifically, some or all of the carbonate ions were removed or replaced with other anions even when layered double hydroxides or carbonate ions that did not contain difficult ion-exchange carbonate ions between layers. The reaction between the layered double hydroxide and the peroxotitanium solution having a pH of 3 or more proceeds easily by simply mixing the two, and a titanium oxide / layered double hydroxide complex is obtained. There is no particular limitation on the mixing method. The temperature during mixing may be room temperature, but in order to promote intercalation, it may be heated to about several tens of degrees Celsius if necessary. The produced titanium oxide / layered double hydroxide complex can be collected by separating the solid content by an appropriate method such as filtration or centrifugation. The peroxotitanium that has entered between the layers of the layered double hydroxide thus obtained gradually releases oxygen and becomes titanium oxide. Alternatively, the conversion from peroxotitanium to titanium oxide may be promoted by heating after the insertion step.
また、インターカレーション工程を行なう前に、層状複水酸化物の層間に存在する難イオン交換性の炭酸イオンの一部又は全部を除去する脱炭酸工程を行なうことが好ましい。炭酸イオンは層間に安定に存在し層状複水酸化物の層間への親和性が高く、炭酸イオンが層間に存在すると、他のイオンとのイオン交換が行われ難くなるため、ペルオキソチタン溶液のような他のアニオンによるイオン交換が困難となるからである。炭酸イオンを層間から除去する方法としては特に限定はないが、例えば、炭酸イオンを含む層状複水酸化物を非特許文献４に記載されているような５００℃程度の加熱焼成を行い、水酸化物から脱炭酸酸化物に変化させた後、水溶液内で再生・再構築する方法や、特許文献８及び非特許文献５に記載されているように、層状複水酸化物中の炭酸イオンを塩化物イオンにイオン交換する方法等が挙げられる。ただし、層間に炭酸イオンを含まず、その他のアニオン（例えば硫酸イオン、硝酸イオン、フッ素イオン、塩素イオン、シュウ素イオン、ヨウ素イオン、水酸イオン等）を層間に含有している層状複水酸化物の場合、脱炭酸工程を行わずにそのまま次のインターカレーション工程を行って良い。また、炭酸イオンを層間に含んでいても、それに加えてその他の前記のようなアニオンも層間に含有している層状複水酸化物の場合は、この脱炭酸工程は必ずしも必要な工程ではなく、行っても行わなくてもよいが、行った方がより酸化チタン微粒子のインターカレーションが進んだ複合体が得られる。
Moreover, before performing an intercalation process, it is preferable to perform the decarboxylation process which removes one part or all part of the difficult ion exchange carbonate ion which exists between the layers of a layered double hydroxide. Carbonate ions exist stably between layers, and the affinity of the layered double hydroxide between layers is high. When carbonate ions are present between layers, ion exchange with other ions is difficult to be performed. This is because ion exchange with other anions becomes difficult. The method for removing carbonate ions from the interlayer is not particularly limited. For example, the layered double hydroxide containing carbonate ions is heated and baked at about 500 ° C. as described in
また、インターカレーション工程において、（仕込んだペルオキソチタン溶液の乾燥固形分質量）／（層状複水酸化物（加熱焼成により該層状複水酸化物の一部又は全部が酸化物となった化合物も含む）の仕込み質量）の値は１以上１０未満であることが好ましく、さらに好ましくは２以上１０未満である。 In addition, in the intercalation process, (the dry solid mass of the charged peroxotitanium solution) / (layered double hydroxide (a compound in which part or all of the layered double hydroxide is converted into an oxide by heating and firing) The value of (including charge) is preferably 1 or more and less than 10, more preferably 2 or more and less than 10.
また、ペルオキソチタン溶液は、水酸化チタンと過酸化水素水との混合物を加熱処理した加熱ペルオキソチタン溶液であることも好ましい。こうであれば、アナターゼ型結晶構造を有する酸化チタンが増大し、光触媒反応の活性が高くなるからである。加熱処理の温度は６０℃以上が好ましく、さらに好ましいのは７０℃以上であり、さらにさらに好ましいのは８０℃以上である。また、高い温度で加熱するため、オートクレーブ等の耐圧容器を用いて加圧すること、あるいは電磁波加熱をすることも好ましい。こうであれば、１００℃以上での加熱処理も可能となり、さらにアナターゼ型結晶構造を発達させることができる。 The peroxotitanium solution is also preferably a heated peroxotitanium solution obtained by heat-treating a mixture of titanium hydroxide and hydrogen peroxide solution. This is because titanium oxide having an anatase type crystal structure increases and the activity of the photocatalytic reaction increases. The temperature of the heat treatment is preferably 60 ° C. or higher, more preferably 70 ° C. or higher, and still more preferably 80 ° C. or higher. Moreover, in order to heat at high temperature, it is also preferable to pressurize using a pressure vessel, such as an autoclave, or to heat electromagnetic waves. If it is like this, the heat processing at 100 degreeC or more will also be attained, and also an anatase type crystal structure can be developed.
本発明で使用するペルオキソチタン溶液は、チタン塩にアルカリを作用させて水酸化チタンとし、さらにこうして得られた水酸化チタンに過酸化水素を作用させることによって得ることができる。チタン塩としては、四塩化チタンや硫酸チタンやシュウ酸チタン等が用いることができ、アルカリとしてはアンモニアや苛性ソーダ等を用いることができる。 The peroxotitanium solution used in the present invention can be obtained by allowing an alkali to act on a titanium salt to form titanium hydroxide, and further allowing hydrogen peroxide to act on the titanium hydroxide thus obtained. Titanium tetrachloride, titanium sulfate, titanium oxalate, or the like can be used as the titanium salt, and ammonia, caustic soda, or the like can be used as the alkali.
さらに、具体的なペルオキソチタン溶液の調製法を示せば、例えば以下のとおりである。
四塩化チタンや硫酸チタンやシュウ酸チタン等のチタン塩の水溶液にアンモニアや苛性ソーダ等のアルカリ溶液を加え、水酸化チタン（別名オルトチタン酸）ゲルを沈殿させる。沈殿した水酸化チタンゲルをデカンテーション等の手段によって水洗し、分離する。この水酸化チタンゲルに過酸化水素水を添加するとＯＨ−の一部が過酸化状態になり、ペルオキソチタンイオンとして溶解、あるいは高分子鎖が低分子に分断された一種のゾル状態のペルオキソチタン溶液となり、余分な過酸化水素は水と酸素に分解する。ペルオキソチタン溶液のｐＨは３以上である必要があるが、さらに好ましくはｐＨが６から８である。このようにして得られた本発明で使用されるペルオキソチタン溶液は、例えば上記のような工程で合成されるＴｉ2Ｏ5（ＯＨ）x (X-2)-（Ｘ＞２）や、（（Ｔｉ２Ｏ５）ｑ（ＯＨ）y (y-2q)-（ｑ／ｙ＞２））等の化学式で表わされるチタン種を含有していると考えられる。
Further, a specific method for preparing the peroxotitanium solution is as follows, for example.
An alkali solution such as ammonia or caustic soda is added to an aqueous solution of a titanium salt such as titanium tetrachloride, titanium sulfate or titanium oxalate to precipitate titanium hydroxide (also called orthotitanic acid) gel. The precipitated titanium hydroxide gel is washed with water by means such as decantation and separated. When hydrogen peroxide water is added to this titanium hydroxide gel, a part of OH − is in a peroxidized state, dissolved as peroxotitanium ions, or becomes a kind of sol peroxotitanium solution in which the polymer chain is divided into low molecules. Excess hydrogen peroxide decomposes into water and oxygen. The pH of the peroxotitanium solution needs to be 3 or more, more preferably 6 to 8. The peroxotitanium solution used in the present invention thus obtained is, for example, Ti 2 O 5 (OH) x (X-2) − (X> 2) synthesized in the above-described steps, ( (Ti 2 O 5 ) q (OH) y (y-2q) − (q / y> 2)) and other titanium species are considered to be contained.
本発明で使用するペルオキソチタン溶液の濃度についても制限はないが乾燥固形分換算の質量％で、２質量％以下が好ましく、さらに好ましくは１．７質量％以下である。このような溶液は、市販のペルオキソチタン溶液を使用しても差し支えなく、例えば鯤コーポレーション製のＰＴＡ８５及びＰＴＡ１７０のような溶液をそのまま、あるいは適宜、希釈して用いることもできる。 Although there is no restriction | limiting also about the density | concentration of the peroxotitanium solution used by this invention, 2 mass% or less is preferable at the mass% of dry solid content conversion, More preferably, it is 1.7 mass% or less. As such a solution, a commercially available peroxotitanium solution may be used. For example, solutions such as PTA85 and PTA170 manufactured by Sakai Corporation may be used as they are or after being appropriately diluted.
（脱炭酸工程）
また、本発明の酸化チタン／層状複水酸化物複合体の製造方法において、インターカレーション工程の前に脱炭酸工程を行なう場合の脱炭酸方法については特に制限はないが、例えば、次のように行なうことができる。すなわち、層間に炭酸イオンを含む層状複水酸化物を、非特許文献４に記載のように、５００℃程度で加熱焼成して水酸化物から脱炭酸酸化物に変化させ、再度、水溶液中に分散して層状複水酸化物として再生させた後（あるいは水溶液中で再生と同時に）、ペルオキソチタン溶液と混合する方法を用いることができる。あるいは特許文献８や非特許文献５に記載されているように、層状複水酸化物中の炭酸イオンを水溶液中で塩化物イオンにイオン交換して脱炭酸体とした後にペルオキソチタン溶液と混合する方法を用いてもよい。
(Decarbonation process)
In the method for producing a titanium oxide / layered double hydroxide composite of the present invention, there is no particular limitation on the decarboxylation method when the decarboxylation step is performed before the intercalation step. Can be done. That is, a layered double hydroxide containing carbonate ions between layers is heated and fired at about 500 ° C. to change from hydroxide to decarbonated oxide as described in
（インターカレーション工程）
次に、インターカレーション工程として、脱炭酸した層状複水酸化物（加熱焼成により該層状複水酸化物の一部又は全部が酸化物となった化合物も含む）をペルオキソチタン溶液と混合する。混合方法としては、（１）層状複水酸化物の乾燥粉末をそのままペルオキソチタン溶液と混合してもよいし、（２）層状複水酸化物に水を加えて湿潤状態とし、これをペルオキソチタン溶液に投入混合してもよい。また、（３）層状複水酸化物を水に分散した懸濁液をペルオキソチタン溶液と混合してもよい。
(Intercalation process)
Next, as an intercalation step, decarboxylated layered double hydroxide (including a compound in which part or all of the layered double hydroxide is converted into an oxide by heating and firing) is mixed with a peroxotitanium solution. As a mixing method, (1) the dry powder of the layered double hydroxide may be mixed with the peroxotitanium solution as it is, or (2) water is added to the layered double hydroxide to make it wet, and this is peroxotitanium. The solution may be charged and mixed. (3) A suspension in which the layered double hydroxide is dispersed in water may be mixed with the peroxotitanium solution.
ペルオキソチタン溶液と、層状複水酸化物（加熱焼成により該層状複水酸化物の一部又は全部が酸化物となった化合物も含む）との混合比は、（仕込んだペルオキソチタン溶液の乾燥固形分質量）／（層状複水酸化物（加熱焼成により該層状複水酸化物の一部又は全部が酸化物となった化合物も含む）の仕込み質量）の値は１以上になることが好ましく、さらに好ましくは２以上である。（仕込んだペルオキソチタン溶液の乾燥固形分質量）／（層状複水酸化物の仕込み質量）が１未満であると、層状複水酸化物層間へのペルオキソチタン種の導入量が不十分であり、ＢＥＴ比表面積が１１０ｍ２／ｇ以上には達せず、またＭＰ法によるマイクロポア細孔容積が０．０１ｃｍ３／ｇ以上とならず、細孔の発達が不十分となる。一方、（仕込んだペルオキソチタン溶液の乾燥固形分質量）／（層状複水酸化物（加熱焼成により該層状複水酸化物の一部又は全部が酸化物となった化合物も含む）の仕込み質量）の値が５を超える場合には、層間に挿入されない酸化チタンが増え、比表面積及び細孔容積の増加が小さくなり、単位質量あたりの吸着量が小さくなる。 The mixing ratio of the peroxotitanium solution and the layered double hydroxide (including a compound in which part or all of the layered double hydroxide is converted into an oxide by heating and firing) is determined by the dry solid state of the charged peroxotitanium solution. The value of (partial mass) / (prepared mass of layered double hydroxide (including a compound in which part or all of the layered double hydroxide is converted into an oxide by heating and firing)) is preferably 1 or more, More preferably, it is 2 or more. When (the dry solid content mass of the charged peroxotitanium solution) / (the charged mass of the layered double hydroxide) is less than 1, the amount of peroxotitanium species introduced between the layered double hydroxide layers is insufficient, The BET specific surface area does not reach 110 m 2 / g or more, and the micropore pore volume by the MP method does not become 0.01 cm 3 / g or more, resulting in insufficient pore development. On the other hand, (the dry solid content mass of the charged peroxotitanium solution) / (the charged mass of the layered double hydroxide (including a compound in which part or all of the layered double hydroxide is converted into an oxide by heating and firing)) When the value exceeds 5, the amount of titanium oxide not inserted between the layers increases, the increase in specific surface area and pore volume decreases, and the amount of adsorption per unit mass decreases.
ペルオキソチタン溶液と層状複水酸化物との混合は、撹拌羽や攪拌子の回転等の通常の撹拌方法を用いればよく、超音波分散等のその他の手段で均質化してもよい。混合処理時の温度についても特に制限はなく、通常は室温で行い、必要に応じて数十℃程度の加温をしても差し支えない。 For mixing the peroxotitanium solution and the layered double hydroxide, a normal stirring method such as rotation of a stirring blade or a stirring bar may be used, and homogenization may be performed by other means such as ultrasonic dispersion. There is no particular limitation on the temperature during the mixing process, and it is usually performed at room temperature, and may be heated to about several tens of degrees Celsius if necessary.
次に、得られた混合懸濁液を脱水、濾過、遠心分離等の適当な手段によって固液分離し、酸化チタン／層状複水酸化物複合体の湿潤固形分を回収する。回収した湿潤固形分を自然乾燥、熱風乾燥、凍結乾燥、超臨界乾燥等の適当な乾燥手段によって乾燥させて、本発明の酸化チタン微粒子が層状複水酸化物の層間に導入された多孔質の酸化チタン／層状複水酸化物複合体を得る。 Next, the obtained mixed suspension is subjected to solid-liquid separation by appropriate means such as dehydration, filtration, and centrifugation, and the wet solid content of the titanium oxide / layered double hydroxide complex is recovered. The recovered wet solid content is dried by an appropriate drying means such as natural drying, hot air drying, freeze drying, supercritical drying, etc., and the titanium oxide fine particles of the present invention are introduced between the layers of the layered double hydroxide. A titanium oxide / layered double hydroxide composite is obtained.
以下、本発明をさらに具体的に示した実施例を比較例と比較しつつ詳細に説明する。 Hereinafter, the present invention will be described in more detail with reference to comparative examples.
＜酸化チタン／層状複水酸化物複合体の調製＞
（実施例１）
まず、脱炭酸工程として、合成炭酸型Ｍｇ−Ａｌ系層状複水酸化物（ＤＨＴ−６、協和化学工業製）を５００℃で焼成して脱炭酸した。次に、インターカレーション工程として、脱炭酸されたＭｇ−Ａｌ系層状複水酸化物の加熱焼成酸化物粉末１ｇをペルオキソチタン溶液（ＰＴＡ１７０、鯤コーポレーション製、ｐＨ：６．５、乾燥固形分濃度：１．７％）１１８ｍｌに投入した。混合比は、（仕込んだペルオキソチタン溶液の乾燥固形分質量）／（加熱焼成酸化物の仕込み質量）の値が２となるようにした。この混合液を室温で攪拌し、均一な懸濁液とした。得られた懸濁液を遠心分離し、得られた固形分を水に分散し再度遠心分離するという洗浄過程を行い、分離された固形分を室温で乾燥し、乳鉢で破砕し、実施例１の酸化チタン／層状複水酸化物複合体を得た。
<Preparation of titanium oxide / layered double hydroxide composite>
Example 1
First, as a decarboxylation step, a synthetic carbonate-type Mg—Al-based layered double hydroxide (DHT-6, manufactured by Kyowa Chemical Industry) was calcined at 500 ° C. to decarboxylate. Next, as an intercalation process, 1 g of calcined oxide powder of decarboxylated Mg—Al-based layered double hydroxide was added to a peroxotitanium solution (PTA170, manufactured by Sakai Corporation, pH: 6.5, dry solid concentration) : 1.7%) to 118 ml. The mixing ratio was set so that the value of (dry solid content mass of the charged peroxotitanium solution) / (prepared mass of heat-fired oxide) was 2. The mixture was stirred at room temperature to make a uniform suspension. The obtained suspension was centrifuged, and the obtained solid content was dispersed in water and centrifuged again. The separated solid content was dried at room temperature and crushed in a mortar. Example 1 The titanium oxide / layered double hydroxide composite was obtained.
（実施例２）
実施例２では、インターカレーション工程における仕込比として、脱炭酸した原料粉末１ｇに対しペルオキソチタン溶液（ＰＴＡ１７０）１７７ｍｌを加え、その他の条件は実施例１と同様とした。この混合比では（仕込んだペルオキソチタン溶液の乾燥固形分質量）／（加熱焼成酸化物の仕込み質量）の値が３となる。
(Example 2)
In Example 2, 177 ml of a peroxotitanium solution (PTA170) was added to 1 g of decarboxylated raw material powder as a feed ratio in the intercalation process, and other conditions were the same as in Example 1. At this mixing ratio, the value of (dry solid content mass of the charged peroxotitanium solution) / (prepared mass of heat-fired oxide) is 3.
（実施例３）
実施例３では、インターカレーション工程における仕込比として、脱炭酸した原料粉末１ｇに対しペルオキソチタン溶液（ＰＴＡ１７０）２３５ｍｌを加え、その他の条件は実施例１と同様とした。この混合比では（仕込んだペルオキソチタン溶液の乾燥固形分質量）／（加熱焼成酸化物の仕込み質量）の値が４となる。
(Example 3)
In Example 3, 235 ml of a peroxotitanium solution (PTA170) was added to 1 g of decarboxylated raw material powder as a feed ratio in the intercalation process, and other conditions were the same as in Example 1. At this mixing ratio, the value of (dry solid content mass of the charged peroxotitanium solution) / (prepared mass of heat-fired oxide) is 4.
（実施例４）
実施例４では、インターカレーション工程における仕込比として、脱炭酸した原料粉末１ｇに対しペルオキソチタン溶液（ＰＴＡ１７０）５３０ｍｌとし、その他の条件は実施例１と同様とした。この混合比では（仕込んだペルオキソチタン溶液の乾燥固形分質量）／（加熱焼成酸化物の仕込み質量）の値が９となる。
(Example 4)
In Example 4, the charge ratio in the intercalation process was 530 ml of peroxotitanium solution (PTA170) per 1 g of the decarboxylated raw material powder, and other conditions were the same as in Example 1. In this mixing ratio, the value of (dry solid content mass of the charged peroxotitanium solution) / (prepared mass of heat-fired oxide) is 9.
（実施例５）
実施例５では、インターカレーション工程における仕込比として、脱炭酸した粉末１ｇに対しペルオキソチタン溶液（ＰＴＡ１７０）５９ｍｌを加え、その他の条件は実施例１と同様とした。この混合比では（仕込んだペルオキソチタン溶液の乾燥固形分質量）／（加熱焼成酸化物の仕込み質量）の値が１となる。
(Example 5)
In Example 5, 59 ml of a peroxotitanium solution (PTA170) was added to 1 g of decarboxylated powder as a charging ratio in the intercalation process, and the other conditions were the same as in Example 1. At this mixing ratio, the value of (dry solid content mass of the charged peroxotitanium solution) / (prepared mass of heat-fired oxide) is 1.
（比較例１）
比較例１では、合成炭酸型Ｍｇ−Ａｌ系層状複水酸化物（ＤＨＴ−６、協和化学工業製）を焼成することなく（すなわち脱炭酸工程を施すことなく）、そのまま原料粉末として使用し、ペルオキソチタン溶液（ＰＴＡ１７０）と混合した。その他の条件は実施例１と同様とした。
(Comparative Example 1)
In Comparative Example 1, a synthetic carbonate-type Mg—Al-based layered double hydroxide (DHT-6, manufactured by Kyowa Chemical Industry Co., Ltd.) is used as it is as a raw material powder without firing (ie, without performing a decarboxylation step). Mixed with peroxotitanium solution (PTA170). Other conditions were the same as in Example 1.
（実施例６）
実施例６では、合成炭酸型Ｍｇ−Ａｌ系層状複水酸化物（ＤＨＴ−６、協和化学工業製）を、非特許文献５に記載の方法と同様、水溶液中のイオン交換により塩素型層状複水酸化物に変換することにより、脱炭酸工程を行なった。詳細は以下のとおりである。
・脱炭酸工程
塩化ナトリウム：０．５ｍｏｌ、酢酸：０．０２５ｍｏｌ、酢酸ナトリウム：０．０２２５ｍｏｌを含む５００ｍｌの水溶液を調製し、そこへ合成炭酸型Ｍｇ−Ａｌ系層状複水酸化物１ｇを投入した。室温で攪拌した後、遠心分離を行い固形分を分離し得られた固形分を水に分散し再度遠心分離するという洗浄過程を行い、塩素型層状複水酸化物の湿潤物を得た。
・インターカレーション工程
次に、この湿潤物の全量をペルオキソチタン溶液（ＰＴＡ８５、鯤コーポレーション製、ｐＨ：６．２、乾燥固形分濃度：０．８５％）２９４ｍｌに投入した。この混合比では（仕込んだペルオキソチタン溶液の乾燥固形分質量）／（層状複水酸化物の仕込み質量）の値が２．５となる。この混合液を室温で攪拌し、均一な懸濁液とした。得られた懸濁液を遠心分離し、得られた固形分を水に分散し再度遠心分離するという洗浄過程を行い、分離された固形分を室温で乾燥し、乳鉢で破砕し、粉末を得た。
(Example 6)
In Example 6, a synthetic carbonate-type Mg—Al-based layered double hydroxide (DHT-6, manufactured by Kyowa Chemical Industry Co., Ltd.) was converted into a chlorine-type layered double hydroxide by ion exchange in an aqueous solution in the same manner as described in Non-Patent Document 5. A decarboxylation step was performed by converting to hydroxide. Details are as follows.
Decarboxylation step A 500 ml aqueous solution containing sodium chloride: 0.5 mol, acetic acid: 0.025 mol, sodium acetate: 0.0225 mol was prepared, and 1 g of synthetic carbonate-type Mg—Al-based layered double hydroxide was added thereto. . After stirring at room temperature, a washing process was performed in which the solid content obtained by centrifugal separation was dispersed in water and centrifuged again to obtain a wet product of chlorine-type layered double hydroxide.
-Intercalation process Next, the whole quantity of this wet substance was thrown into 294 ml of peroxotitanium solutions (PTA85, the Sakai Corporation make, pH: 6.2, dry solid content concentration: 0.85%). At this mixing ratio, the value of (dry solid content mass of the charged peroxotitanium solution) / (charged mass of the layered double hydroxide) is 2.5. The mixture was stirred at room temperature to make a uniform suspension. The resulting suspension is centrifuged, and the resulting solid is dispersed in water and centrifuged again. The separated solid is dried at room temperature and crushed in a mortar to obtain a powder. It was.
（実施例７）
実施例７では、インターカレーション工程における仕込比として、塩素型層状複水酸化物の湿潤物の全量に対しペルオキソチタン溶液（ＰＴＡ８５）の混合量を５８８ｍｌとし、その他の条件は実施例６と同様とした。この混合比では（仕込んだペルオキソチタン溶液の乾燥固形分質量）／（層状複水酸化物の仕込み質量）の値が５となる。
(Example 7)
In Example 7, as the charging ratio in the intercalation process, the mixing amount of the peroxotitanium solution (PTA85) was set to 588 ml with respect to the total amount of the hydrated chlorine-type layered double hydroxide, and the other conditions were the same as in Example 6. It was. At this mixing ratio, the value of (dry solid content mass of the charged peroxotitanium solution) / (charged mass of the layered double hydroxide) is 5.
（実施例８）
実施例８ではペルオキソチタン溶液（ＰＴＡ８５）を、予め９５℃、１２時間の加熱処理を施し、その他の条件は実施例６と同様（すなわち（仕込んだペルオキソチタン溶液の乾燥固形分質量）／（層状複水酸化物の仕込み質量）＝２．５）とした。
(Example 8)
In Example 8, the peroxotitanium solution (PTA85) was preliminarily subjected to a heat treatment at 95 ° C. for 12 hours, and the other conditions were the same as in Example 6 (that is, (the dry solid mass of the charged peroxotitanium solution) / (layered) Preparation mass of double hydroxide) = 2.5).
（実施例９）
実施例９ではペルオキソチタン溶液（ＰＴＡ８５）を、予め６０℃、８８時間の加熱処理を施し、その他の条件は実施例６と同様（すなわち（仕込んだペルオキソチタン溶液の乾燥固形分質量）／（層状複水酸化物の仕込み質量）＝２．５）とした。
Example 9
In Example 9, the peroxotitanium solution (PTA85) was preliminarily heated at 60 ° C. for 88 hours, and the other conditions were the same as in Example 6 (that is, (the dry solid mass of the charged peroxotitanium solution) / (layered) Preparation mass of double hydroxide) = 2.5).
＜評 価＞
以上のようにして得られた実施例１〜７の酸化チタン／層状複水酸化物複合体と、比較例１の粉末に対して、窒素吸着法によるＢＥＴ法比表面積測定、ＭＰ法によるマイクロポア解析、Ｘ線回折測定及び蛍光Ｘ線分析法による酸化チタン含有量測定を行なった。
<Evaluation>
For the titanium oxide / layered double hydroxide composites of Examples 1 to 7 obtained as described above and the powder of Comparative Example 1, BET specific surface area measurement by nitrogen adsorption method, micropore by MP method The titanium oxide content was measured by analysis, X-ray diffraction measurement and fluorescent X-ray analysis.
（結 果）
実施例１〜９の酸化チタン／層状複水酸化物複合体及び比較例１で得られた粉末についての、窒素吸着法によるＢＥＴ法比表面積・ＭＰ法マイクロポア容積及び蛍光Ｘ線分析法による酸化チタン含有量を表１に示す。また比較のため、実施例１〜９及び比較例１の調製に際し、使用した出発原料である合成炭酸型Ｍｇ−Ａｌ系層状複水酸化物（ＤＨＴ−６、協和化学工業製）の測定結果も表１に示す。
(Result)
About the titanium oxide / layered double hydroxide complex of Examples 1 to 9 and the powder obtained in Comparative Example 1, oxidation by the BET method specific surface area, MP method micropore volume and fluorescent X-ray analysis method by nitrogen adsorption method The titanium content is shown in Table 1. For comparison, the measurement results of the synthetic carbonate-type Mg—Al-based layered double hydroxide (DHT-6, manufactured by Kyowa Chemical Industry Co., Ltd.), which is the starting material used in the preparation of Examples 1 to 9 and Comparative Example 1, are also included. Table 1 shows.
表１に示すように、（仕込んだペルオキソチタン溶液の乾燥固形分質量）／（層状複水酸化物の仕込み質量）の値が２以上である実施例１〜４及び６〜９の酸化チタン／層状複水酸化物複合体は、１６８ｍ２／ｇ以上の高い比表面積を示した。一方、出発原料の炭酸型層状複水酸化物（ＤＨＴ−６、協和化学工業製）の比表面積は１３ｍ２／ｇであり、脱炭酸していない炭酸型層状複水酸化物をそのまま原料として使用した比較例１の粉末の比表面積は２５ｍ２／ｇと、極めて低い値であった。さらに脱炭酸した層状複水酸化物に対して等倍の質量比でペルオキソチタン溶液を作用させた実施例５の酸化チタン／層状複水酸化物複合体は１２７ｍ２／ｇであり、２倍以上の質量比でペルオキソチタンを作用させた実施例１〜４及び６〜９の粉末と比較して若干低い比表面積を示した。 As shown in Table 1, titanium oxides of Examples 1 to 4 and 6 to 9 having a value of (dry solid content of charged peroxotitanium solution) / (prepared mass of layered double hydroxide) of 2 or more / The layered double hydroxide composite exhibited a high specific surface area of 168 m 2 / g or more. On the other hand, the carbonic acid layered double hydroxide (DHT-6, manufactured by Kyowa Chemical Industry Co., Ltd.), the starting material, has a specific surface area of 13 m 2 / g. The specific surface area of the powder of Comparative Example 1 was an extremely low value of 25 m 2 / g. Furthermore, the titanium oxide / layered double hydroxide complex of Example 5 in which the peroxotitanium solution was allowed to act on the decarboxylated layered double hydroxide at an equal mass ratio was 127 m 2 / g, which was 2 times or more. Compared with the powders of Examples 1 to 4 and 6 to 9 in which peroxotitanium was allowed to act at a mass ratio of 1, the specific surface area was slightly lower.
表１から分かるように、出発原料の層状複水酸化物は層間が開いていないため、そのマイクロポア容積は０．００１ｃｍ３／ｇ未満とごく小さい。一方、実施例１〜９のマイクロポア容積は０．０４６ｃｍ３／ｇ以上の値を示し、層間が開いて細孔が発達していることが分かる。また比較例１の粉末は、ペルオキソチタンを作用させた層状複水酸化物が脱炭酸されていないため、マイクロポア容積は０．００１ｃｍ３／ｇ未満と極めて小さかった。 As can be seen from Table 1, since the layered double hydroxide of the starting material is not open between layers, the micropore volume is as small as less than 0.001 cm 3 / g. On the other hand, the micropore volume of Examples 1 to 9 shows a value of 0.046 cm 3 / g or more, and it can be seen that the layers are open and the pores are developed. In addition, the powder of Comparative Example 1 had a micropore volume of less than 0.001 cm 3 / g because the layered double hydroxide treated with peroxotitanium was not decarboxylated.
図１〜３に、実施例１〜９の酸化チタン／層状複水酸化物複合体、比較例１の粉末、及び、出発原料の層状複水酸化物（ＤＨＴ−６、協和化学工業製）についてのＭＰ法マイクロポア細孔分布曲線を示す。原料の層状複水酸化物のマイクロポア容積はごく小さい。実施例１及び２の粉末は細孔分布の極大を示す細孔分布直径が１０．６〜１０．７Åを示した。実施例３、４及び６、７の粉末は細孔直径が小さくなるにつれ細孔容積が大きくなり、極大値は９Å未満であり、発達したマイクロポアの存在を示している。一方、脱炭酸していない炭酸型層状複水酸化物をそのまま原料として使用した比較例１の粉末については、マイクロポア容積はごく小さい。また脱炭酸した層状複水酸化物に対して等倍の質量比でペルオキソチタン溶液を作用させた実施例５の粉末は、細孔分布が幅広く細孔容積から判断すると実施例１〜４及び６、７の粉末と比較すればマイクロポアの発達が少ないと推測される。実施例８及び９に関しては、実施例１〜７の粉末に比較してやや大きめのマイクロポアであるが、細孔容積から判断して充分に発達したマイクロポアを有している。 1-3, the titanium oxide / layered double hydroxide composite of Examples 1-9, the powder of Comparative Example 1, and the layered double hydroxide of the starting material (DHT-6, manufactured by Kyowa Chemical Industry) The MP method micropore pore distribution curve of is shown. The micropore volume of the raw material layered double hydroxide is very small. The powders of Examples 1 and 2 had a pore distribution diameter of 10.6 to 10.7 mm indicating the maximum pore distribution. The powders of Examples 3, 4 and 6, 7 increased in pore volume as the pore diameter decreased, and the maximum value was less than 9 mm, indicating the presence of developed micropores. On the other hand, the micropore volume is very small for the powder of Comparative Example 1 in which the carbonated layered double hydroxide that has not been decarboxylated is used as a raw material. In addition, the powder of Example 5 in which the peroxotitanium solution was allowed to act on the decarboxylated layered double hydroxide at an equal mass ratio had a wide pore distribution, and Examples 1-4 and 6 were judged from the pore volume. Therefore, it is estimated that the micropores are less developed compared to the powder No. 7. Examples 8 and 9 are slightly larger micropores than the powders of Examples 1 to 7, but have sufficiently developed micropores as judged from the pore volume.
図４〜８に実施例１〜９の酸化チタン／層状複水酸化物複合体の粉末、比較例１の粉末、出発原料の炭酸型層状複水酸化物（ＤＨＴ−６、協和化学工業製）のＸ線回折パターンを示す。 FIGS. 4 to 8 show powders of titanium oxide / layered double hydroxide composites of Examples 1 to 9, powder of Comparative Example 1, and starting carbonic acid layered double hydroxide (DHT-6, manufactured by Kyowa Chemical Industry). The X-ray diffraction pattern of is shown.
図４において原料の層状複水酸化物は２θ：１１°付近に（００３）回折線ピークを示している。一方、比較例１は（００３）回折線ピークの強度はやや小さくなったものの、回折線の２θ角度の位置に変化はない。これは脱炭酸していない炭酸型層状複水酸化物を使用した場合には、酸化チタン分が層状複水酸化物の層間に入らず、層間が拡大していないことを示している。 In FIG. 4, the layered double hydroxide as a raw material has a (003) diffraction line peak around 2θ: 11 °. On the other hand, in Comparative Example 1, although the intensity of the (003) diffraction line peak is slightly reduced, there is no change in the position of the 2θ angle of the diffraction line. This indicates that when a carbonate-type layered double hydroxide that has not been decarboxylated is used, the titanium oxide component does not enter between the layers of the layered double hydroxide, and the layers do not expand.
図５は、原料の炭酸型層状複水酸化物の加熱焼成による脱炭酸物に対し、ペルオキソチタンによる酸化チタン分の配合比を変えた合成物である実施例１〜５のＸ線回折パターンを示している。実施例１〜４では、仕込み質量比を２〜９に増加させるにつれ、２θ：１１°付近の（００３）回折線ピークが弱くなりやがて消失し、それに対応して２θ：５〜９°付近のピーク強度が大きくなっている。低角側に現れたこのピークは（００３）回折線がシフトしたものであり、すなわち層間距離が拡大している証拠である。それに対し酸化チタン／層状複水酸化物の仕込み質量比が１である実施例５は、２θ：１１°付近の原料層状複水酸化物の（００３）回折線がごく弱くなっている。したがって何らかの変化は起きているだろうが、２θの低角度側に層間の拡大を示す（００３）回折線は示されていない。したがって実施例５では、実施例２〜４と比較すると、層間への酸化チタンの導入が少ないと推測される。 FIG. 5 shows X-ray diffraction patterns of Examples 1 to 5, which are synthesized products in which the mixing ratio of titanium oxide by peroxotitanium is changed with respect to the decarboxylated product by heating and baking the carbonic acid layered double hydroxide as a raw material. Show. In Examples 1 to 4, as the charge mass ratio was increased to 2 to 9, the (003) diffraction line peak near 2θ: 11 ° was weakened and disappeared, and correspondingly, 2θ: around 5-9 °. The peak intensity is increased. This peak appearing on the low angle side is a shift of the (003) diffraction line, that is, evidence that the interlayer distance is increased. On the other hand, in Example 5 where the charged mass ratio of titanium oxide / layered double hydroxide is 1, the (003) diffraction line of the raw material layered double hydroxide near 2θ: 11 ° is very weak. Therefore, although some change may have occurred, the (003) diffraction line showing the expansion between layers is not shown on the low angle side of 2θ. Therefore, in Example 5, compared with Examples 2-4, it is estimated that there is little introduction | transduction of the titanium oxide between layers.
図６は、原料の炭酸型層状複水酸化物の塩素置換体に対し、ペルオキソチタンによる酸化チタン分の配合比を変えた合成物である実施例６及び７と原料の炭酸型層状複水酸化物のＸ線回折パターンを示している。実施例６及び７共、２θ：１１°付近の（００３）回折線を示しているが、その強度は原料の炭酸型層状複水酸化物に比べ、ごく小さい。また酸化チタン／層状複水酸化物の仕込み質量比がより大きい実施例７の方が実施例６よりも（００３）回折線の強度が小さくなっていて、酸化チタン分の層間導入が進んでいることを示している。実施例６の２θ：１１°付近の（００３）回折線ピークはトップが割れた二重線を示している。この二重線は、非特許文献５によれば、高角側のやや小さいピークが炭酸型の層状複水酸化物による（００３）回折線であり、低角側の比較的大きなピークが塩素置換型の（００３）回折線であると記されている。したがって実施例６の合成においては原料に塩素置換体を使用したが、酸化チタン分の配合量が少ないためまだ未反応の塩素型の層状複水酸化物が部分的に残っており、また他の一部分は合成懸濁液中に少量含まれていた炭酸イオンが塩素イオンよりもペルオキソチタン種よりも層状複水酸化物へのイオン交換性が高いため、炭酸型に戻り合成物に残ったと説明できる。実施例７の２θ：１１°付近の（００３）回折線の２θ角度位置は実施例６の炭酸型のピークに一致している。したがって実施例７の合成においては、酸化チタン分の配合量が充分なため未反応の塩素置換体はほとんど残っていず、合成懸濁液中に少量含まれていた炭酸イオンのために炭酸型に戻ったごく一部の層状複水酸化物が回折ピークを示していると説明できる。
実施例６及び７共、２θ：１１°付近の（００３）回折線の他に、２θ：２θ：５〜９°付近のピークが現れている。このことはやはり、実施例６及び７共、層状複水酸化物の層間に酸化チタンが導入されたことにより拡大されたことを示している。
FIG. 6 shows Examples 6 and 7 which are compounds in which the mixing ratio of titanium oxide by peroxotitanium is changed with respect to the chlorine substitution product of the raw material carbonate type layered double hydroxide and the raw material carbonate type layered double hydroxide. The X-ray diffraction pattern of the object is shown. Both Examples 6 and 7 show (003) diffraction lines near 2θ: 11 °, but the intensity is very small compared to the carbonic acid layered double hydroxide as a raw material. Further, Example 7 having a larger charged mass ratio of titanium oxide / layered double hydroxide has a lower intensity of (003) diffraction line than Example 6, and the introduction of the titanium oxide layer is progressing. It is shown that. The (003) diffraction line peak in the vicinity of 2θ: 11 ° in Example 6 shows a double line in which the top is broken. According to Non-Patent Document 5, this double line is a (003) diffraction line with a slightly small peak on the high angle side due to the carbonate-type layered double hydroxide, and a relatively large peak on the low angle side is a chlorine substitution type. Of (003) diffraction lines. Therefore, in the synthesis of Example 6, a chlorine-substituted product was used as a raw material, but the unreacted chlorine-type layered double hydroxide remained partially because of the small amount of titanium oxide, and other It can be explained that some of the carbonate ions contained in a small amount in the synthetic suspension were returned to the carbonate type and remained in the composite because the ion exchange to the layered double hydroxide was higher than the peroxotitanium species than the chlorine ions. . The 2θ angular position of the (003) diffraction line in the vicinity of 2θ: 11 ° in Example 7 coincides with the carbonic acid type peak in Example 6. Therefore, in the synthesis of Example 7, since the blending amount of the titanium oxide is sufficient, almost no unreacted chlorine substitute remains, and the carbonate ion contained in a small amount in the synthetic suspension is changed to the carbonate type. It can be explained that only a part of the layered double hydroxide that has returned exhibits a diffraction peak.
In Examples 6 and 7, in addition to the (003) diffraction line near 2θ: 11 °, a peak near 2θ: 2θ: 5-9 ° appears. This also shows that both Examples 6 and 7 were enlarged by introducing titanium oxide between the layers of the layered double hydroxide.
図７は、加熱処理をしたペルオキソチタン溶液を用いた実施例８、９及び出発原料の炭酸型層状複水酸化物（ＬＤＨ）についてのＸ線回折パターンである。層状複水酸化物の（００３）回折線に対応するピークは実施例８、９では小さくなっており、低角側に不明瞭なショルダーが現れている。このショルダーの中に、層間が拡大した（００３）回折線ピークが存在しているものと考えられる。図８は、実施例６、８及び９に関する高角度領域のＸ線回折パターンである。この図から、加熱処理をしたペルオキソチタン溶液を用いた実施例８，９では、アナターゼ型結晶構造に由来するピーク（図中「Ａ」で示したピーク）が現れており、図８及び図７から、アナターゼ型結晶構造の酸化チタンが層間に存在していることが分かった。 FIG. 7 shows X-ray diffraction patterns of Examples 8 and 9 using a heat-treated peroxotitanium solution and starting carbonate type layered double hydroxide (LDH). The peak corresponding to the (003) diffraction line of the layered double hydroxide is small in Examples 8 and 9, and an unclear shoulder appears on the low angle side. It is considered that a (003) diffraction line peak in which the interlayer is enlarged exists in this shoulder. FIG. 8 is a high angle region X-ray diffraction pattern for Examples 6, 8 and 9. From this figure, in Examples 8 and 9 using the heat-treated peroxotitanium solution, a peak derived from the anatase type crystal structure (peak indicated by “A” in the figure) appears, and FIG. 8 and FIG. From the results, it was found that titanium oxide having an anatase type crystal structure was present between the layers.
図９に、表１に示した値を基に、酸化チタン／層状複水酸化物（該層状複水酸化物の加熱焼成脱炭酸酸化物も含む）の仕込み質量比と合成物の酸化チタン含有量の関係を示す。この図から、実施例１〜５のように、層状複水酸化物の加熱脱炭酸物を使用した場合には、（仕込んだペルオキソチタン溶液の乾燥固形分質量）／（層状複水酸化物の仕込み質量）の値がおよそ４付近で酸化チタン含有量の増加が頭打ちとなり、４を超えるとペルオキソチタン分を増やしても酸化チタン含有量の増加はわずかとなった。また層状複水酸化物の塩素置換体を使用し、（仕込んだペルオキソチタン溶液の乾燥固形分質量）／（層状複水酸化物の仕込み質量）の値を２．５とした実施例６の粉末並びに同様の塩素置換体を使用して値を５とした実施例７の酸化チタン／層状複水酸化物複合体では、酸化チタン含有量は７５及び７７質量％と高い含有量を示した。また予め加熱したペルオキソチタン溶液を使用し、（仕込んだペルオキソチタン溶液の乾燥固形分質量）／（層状複水酸化物の仕込み質量）の値を２．５とした実施例８及び９の酸化チタン／層状複水酸化物複合体では、酸化チタン含有量は６１及び５９質量％と高い含有量を示した。 In FIG. 9, based on the values shown in Table 1, the charged mass ratio of titanium oxide / layered double hydroxide (including thermally calcined decarbonated oxide of the layered double hydroxide) and the composite titanium oxide content The relationship of quantity is shown. From this figure, as in Examples 1 to 5, when the heated decarboxylated layered double hydroxide was used, (the dry solid content mass of the charged peroxotitanium solution) / (layered double hydroxide When the value of (prepared mass) was about 4, the increase in the titanium oxide content reached its peak, and when it exceeded 4, the increase in the titanium oxide content was slight even if the peroxotitanium content was increased. Further, the powder of Example 6 using a chlorine-substituted product of layered double hydroxide and having a value of (dry solid content of charged peroxotitanium solution) / (charged weight of layered double hydroxide) of 2.5. In addition, in the titanium oxide / layered double hydroxide composite of Example 7 having a value of 5 using the same chlorine substitution product, the titanium oxide content was as high as 75 and 77% by mass. In addition, a preheated peroxotitanium solution was used, and the titanium oxides of Examples 8 and 9 in which the value of (dry solid content of charged peroxotitanium solution) / (charged mass of layered double hydroxide) was 2.5. In the layered double hydroxide composite, the titanium oxide content was as high as 61 and 59% by mass.
以上のように、実施例１〜７から得られた酸化チタン／層状複水酸化物複合体と、出発原料とした合成炭酸型Ｍｇ−Ａｌ系層状複水酸化物の粉末及び比較例１から得られた粉末の特性の比較から、細孔が充分に発達した酸化チタン／層状複水酸化物複合体を合成するためには、脱炭酸した層状複水酸化物を使用することが必要であること、ペルオキソチタン溶液を使用すること、さらには（仕込んだペルオキソチタン溶液の乾燥固形分質量）／（層状複水酸化物（加熱焼成により該層状複水酸化物の一部又は全部が酸化物となった化合物も含む）の仕込み質量）の値が１以上であることが好ましいことが明らかとなった。 As described above, obtained from the titanium oxide / layered double hydroxide composite obtained from Examples 1 to 7, the powder of the synthetic carbonate-type Mg—Al-based layered double hydroxide as a starting material, and Comparative Example 1 From the comparison of the properties of the obtained powders, it is necessary to use decarboxylated layered double hydroxide in order to synthesize titanium oxide / layered double hydroxide composites with sufficiently developed pores. , Using a peroxotitanium solution, and further (the dry solid mass of the charged peroxotitanium solution) / (layered double hydroxide (a part or all of the layered double hydroxide becomes an oxide by heating and baking). It was revealed that the value of the charged mass) of the compound (including the above-mentioned compounds) is preferably 1 or more.
また実施例１〜５と実施例６及び７との比較から、炭酸イオンを層間に含む層状複水酸化物の脱炭酸の方法は加熱焼成法、イオン交換法のどちらでもよいことが明らかである。 Moreover, it is clear from the comparison between Examples 1 to 5 and Examples 6 and 7 that the method for decarboxylation of the layered double hydroxide containing carbonate ions between the layers may be either a heat firing method or an ion exchange method. .
（光触媒性能測定）
実施例６、８及び９に関して、光触媒性能試験を行なった。試験は次のように行った。直径９０ｍｍのシャーレに酸化チタン／層状複水酸化物複合体の水分散体を拡げ、乾燥した。酸化チタン／層状複水酸化物複合体の乾燥物は、シャーレの底全体に皮膜状に付着した。乾燥後のシャーレ中の酸化チタン／層状複水酸化物複合体の量は、０．１ｇとなるように調節した。このシャーレを、まず、ブラックライトを用いて試験片に紫外線（１ｍＷ／ｃｍ2）を２４時間照射した後、試験片をテドラーバッグ（容量５Ｌ）内に封入する。次に試験の対象となるアセトアルデヒドガスを所定の割合で含有する空気を３Ｌ注入し、暗所に放置する。この間、テドラーバッグ内の空気を所定時間ごとにシリンジで抜き取り、ガスクロマトグラフで対象ガスの濃度の経時変化を測定した。そして、ガス濃度がほとんど変化しなくなった時点の濃度を初期濃度とし、その時点からブラックライトによって紫外線（１ｍＷ／ｃｍ2）を照射し、アセトアルデヒド光触媒分解反応を行なった。アセトアルデヒドガスの初期濃度は７０ｐｐｍとした。紫外線照射後のテドラーバッグ内のガス濃度をガスクロマトグラフで測定し、アセトアルデヒドの除去率を求めた。
(Photocatalytic performance measurement)
A photocatalytic performance test was performed on Examples 6, 8 and 9. The test was conducted as follows. An aqueous dispersion of titanium oxide / layered double hydroxide composite was spread on a petri dish having a diameter of 90 mm and dried. The dried product of the titanium oxide / layered double hydroxide composite adhered to the entire bottom of the petri dish. The amount of the titanium oxide / layered double hydroxide complex in the petri dish after drying was adjusted to be 0.1 g. First, the petri dish was irradiated with ultraviolet light (1 mW / cm 2 ) for 24 hours using a black light, and then the test piece was enclosed in a Tedlar bag (capacity 5 L). Next, 3 L of air containing a predetermined ratio of acetaldehyde gas to be tested is injected and left in the dark. During this time, the air in the Tedlar bag was extracted with a syringe every predetermined time, and the change over time in the concentration of the target gas was measured with a gas chromatograph. And the density | concentration at the time of almost no change in gas density | concentration was made into the initial stage density | concentration, and the ultraviolet light (1mW / cm < 2 >) was irradiated with the black light from that time, and the acetaldehyde photocatalytic decomposition reaction was performed. The initial concentration of acetaldehyde gas was 70 ppm. The gas concentration in the Tedlar bag after ultraviolet irradiation was measured with a gas chromatograph, and the removal rate of acetaldehyde was determined.
その結果、表２に示すように、９５℃で１２時間の加熱処理をしたペルオキソチタン溶液を用いた実施例８では、１００分の紫外線照射でのアセトアルデヒドの除去率が８３％と高かったのに対し、加熱処理をしていないペルオキソチタン溶液を用いた実施例６では、１００分の紫外線照射を行っても、アセトアルデヒド除去率が１３％と低かった。これは、前述したように、ペルオキソチタン溶液の加熱処理によって、光触媒活性の高いアナターゼ型結晶構造を有する酸化チタンが生成した（図８参照）ことによるものと考えられる。また実施例９のように、ペルオキソチタン溶液の加熱温度が６０℃と低温であっても８８時間のような長時間の加熱処理を施した溶液を用いれば、そのアセトアルデヒド除去率は実施例６に比較して改善された。 As a result, as shown in Table 2, in Example 8 using a peroxotitanium solution that had been heat-treated at 95 ° C. for 12 hours, the removal rate of acetaldehyde after 100 minutes of UV irradiation was as high as 83%. On the other hand, in Example 6 using a peroxotitanium solution that was not heat-treated, the acetaldehyde removal rate was as low as 13% even after 100 minutes of ultraviolet irradiation. As described above, this is considered due to the fact that titanium oxide having an anatase type crystal structure with high photocatalytic activity was generated by the heat treatment of the peroxotitanium solution (see FIG. 8). Further, as in Example 9, when a solution subjected to a long-time heat treatment such as 88 hours is used even when the heating temperature of the peroxotitanium solution is as low as 60 ° C., the acetaldehyde removal rate is as in Example 6. Compared with improvement.
この発明は上記発明の実施の態様及び実施例の説明に何ら限定されるものではない。特許請求の範囲を逸脱せず、当業者が容易に想到できる範囲で種々の変形態様もこの発明に含まれる。 The present invention is not limited to the description of the embodiments and examples of the invention described above. Various modifications are also included in the present invention as long as those skilled in the art can easily conceive without departing from the scope of the claims.
本発明の酸化チタン／層状複水酸化物複合体は高比表面積に起因する吸着性能を有し、また酸化チタン微粒子を含有していることから、吸着材、分離材、光触媒材料、環境浄化材料などの幅広い分野に利用されることが期待される。 The titanium oxide / layered double hydroxide composite of the present invention has an adsorption performance resulting from a high specific surface area and contains titanium oxide fine particles, so that it is an adsorbent, a separating material, a photocatalyst material, and an environmental purification material. It is expected to be used in a wide range of fields.
Claims (11)
前記インターカレーション工程を行う前に、層状複水酸化物の層間に存在する炭酸イオンの一部又は全部を除去する脱炭酸工程を行うことを特徴とする酸化チタン／層状複水酸化物複合体の製造方法。 By mixing the layered double hydroxide or a compound in which a part or all of the layered double hydroxide is converted into an oxide by heating and baking with a peroxotitanium solution having a pH of 3 or more, have a intercalation process by inserting a titanium oxide and titanium oxide / layered double hydroxide complexes in layers,
Before performing the intercalation step, a titanium dioxide / layered double hydroxide composite is characterized in that a decarboxylation step is performed to remove some or all of the carbonate ions present between the layers of the layered double hydroxide. Manufacturing method.
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