JP3940393B2 - Method for producing photocatalytic titanium oxide - Google Patents
Method for producing photocatalytic titanium oxide Download PDFInfo
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- JP3940393B2 JP3940393B2 JP2003375286A JP2003375286A JP3940393B2 JP 3940393 B2 JP3940393 B2 JP 3940393B2 JP 2003375286 A JP2003375286 A JP 2003375286A JP 2003375286 A JP2003375286 A JP 2003375286A JP 3940393 B2 JP3940393 B2 JP 3940393B2
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- titanium oxide
- titanium
- aqueous solution
- oxide precursor
- photocatalytic
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- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 title claims description 172
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 title claims description 123
- 230000001699 photocatalysis Effects 0.000 title claims description 52
- 238000004519 manufacturing process Methods 0.000 title claims description 25
- 239000002243 precursor Substances 0.000 claims description 73
- 239000013078 crystal Substances 0.000 claims description 59
- 239000007864 aqueous solution Substances 0.000 claims description 45
- 229910052719 titanium Inorganic materials 0.000 claims description 24
- 239000010936 titanium Substances 0.000 claims description 24
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 22
- 238000010304 firing Methods 0.000 claims description 22
- 230000002378 acidificating effect Effects 0.000 claims description 20
- 239000011941 photocatalyst Substances 0.000 claims description 15
- 239000002994 raw material Substances 0.000 claims description 11
- 239000002002 slurry Substances 0.000 claims description 10
- 238000004090 dissolution Methods 0.000 claims description 8
- 125000002887 hydroxy group Chemical group [H]O* 0.000 claims description 8
- 238000001556 precipitation Methods 0.000 claims description 8
- XJDNKRIXUMDJCW-UHFFFAOYSA-J titanium tetrachloride Chemical compound Cl[Ti](Cl)(Cl)Cl XJDNKRIXUMDJCW-UHFFFAOYSA-J 0.000 claims description 8
- QGZKDVFQNNGYKY-UHFFFAOYSA-N ammonia Natural products N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 5
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonium chloride Substances [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 claims description 3
- 239000002253 acid Substances 0.000 claims description 3
- 238000001354 calcination Methods 0.000 claims description 2
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims 1
- 235000011114 ammonium hydroxide Nutrition 0.000 claims 1
- 230000003647 oxidation Effects 0.000 claims 1
- 238000007254 oxidation reaction Methods 0.000 claims 1
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 27
- 238000012360 testing method Methods 0.000 description 19
- 238000006243 chemical reaction Methods 0.000 description 13
- 239000000243 solution Substances 0.000 description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 11
- 239000000843 powder Substances 0.000 description 9
- 238000012545 processing Methods 0.000 description 9
- 238000000034 method Methods 0.000 description 8
- 238000000354 decomposition reaction Methods 0.000 description 7
- 239000002552 dosage form Substances 0.000 description 7
- 239000007791 liquid phase Substances 0.000 description 7
- 230000007704 transition Effects 0.000 description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- 238000002441 X-ray diffraction Methods 0.000 description 6
- 239000000499 gel Substances 0.000 description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 5
- 229910052760 oxygen Inorganic materials 0.000 description 5
- 239000001301 oxygen Substances 0.000 description 5
- 238000003756 stirring Methods 0.000 description 5
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- 239000012298 atmosphere Substances 0.000 description 4
- 239000007789 gas Substances 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 239000011148 porous material Substances 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- 239000002904 solvent Substances 0.000 description 4
- 239000000126 substance Substances 0.000 description 4
- VXUYXOFXAQZZMF-UHFFFAOYSA-N titanium(IV) isopropoxide Chemical compound CC(C)O[Ti](OC(C)C)(OC(C)C)OC(C)C VXUYXOFXAQZZMF-UHFFFAOYSA-N 0.000 description 4
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 239000003054 catalyst Substances 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 3
- 229910052753 mercury Inorganic materials 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- 239000012071 phase Substances 0.000 description 3
- LLZRNZOLAXHGLL-UHFFFAOYSA-J titanic acid Chemical compound O[Ti](O)(O)O LLZRNZOLAXHGLL-UHFFFAOYSA-J 0.000 description 3
- 238000011282 treatment Methods 0.000 description 3
- 238000005406 washing Methods 0.000 description 3
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- 241000195493 Cryptophyta Species 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 2
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 description 2
- 230000032683 aging Effects 0.000 description 2
- 229910021529 ammonia Inorganic materials 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 239000007795 chemical reaction product Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000004817 gas chromatography Methods 0.000 description 2
- QNVRIHYSUZMSGM-UHFFFAOYSA-N hexan-2-ol Chemical compound CCCCC(C)O QNVRIHYSUZMSGM-UHFFFAOYSA-N 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000000463 material Substances 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
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 description 2
- 238000000746 purification Methods 0.000 description 2
- 230000001629 suppression Effects 0.000 description 2
- 230000036962 time dependent Effects 0.000 description 2
- -1 titanium oxoacid salts Chemical class 0.000 description 2
- 229910000349 titanium oxysulfate Inorganic materials 0.000 description 2
- 229910000348 titanium sulfate Inorganic materials 0.000 description 2
- UBZYKBZMAMTNKW-UHFFFAOYSA-J titanium tetrabromide Chemical compound Br[Ti](Br)(Br)Br UBZYKBZMAMTNKW-UHFFFAOYSA-J 0.000 description 2
- XROWMBWRMNHXMF-UHFFFAOYSA-J titanium tetrafluoride Chemical compound [F-].[F-].[F-].[F-].[Ti+4] XROWMBWRMNHXMF-UHFFFAOYSA-J 0.000 description 2
- YONPGGFAJWQGJC-UHFFFAOYSA-K titanium(iii) chloride Chemical compound Cl[Ti](Cl)Cl YONPGGFAJWQGJC-UHFFFAOYSA-K 0.000 description 2
- NLPMQGKZYAYAFE-UHFFFAOYSA-K titanium(iii) fluoride Chemical compound F[Ti](F)F NLPMQGKZYAYAFE-UHFFFAOYSA-K 0.000 description 2
- RYHBNJHYFVUHQT-UHFFFAOYSA-N 1,4-Dioxane Chemical compound C1COCCO1 RYHBNJHYFVUHQT-UHFFFAOYSA-N 0.000 description 1
- QNVRIHYSUZMSGM-LURJTMIESA-N 2-Hexanol Natural products CCCC[C@H](C)O QNVRIHYSUZMSGM-LURJTMIESA-N 0.000 description 1
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- CPELXLSAUQHCOX-UHFFFAOYSA-M Bromide Chemical compound [Br-] CPELXLSAUQHCOX-UHFFFAOYSA-M 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- RWSOTUBLDIXVET-UHFFFAOYSA-N Dihydrogen sulfide Chemical class S RWSOTUBLDIXVET-UHFFFAOYSA-N 0.000 description 1
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 description 1
- 241000233866 Fungi Species 0.000 description 1
- 229910002651 NO3 Inorganic materials 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 229910019142 PO4 Inorganic materials 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 150000001299 aldehydes Chemical class 0.000 description 1
- 150000001412 amines Chemical class 0.000 description 1
- 235000019270 ammonium chloride Nutrition 0.000 description 1
- 239000003125 aqueous solvent Substances 0.000 description 1
- JRPBQTZRNDNNOP-UHFFFAOYSA-N barium titanate Chemical compound [Ba+2].[Ba+2].[O-][Ti]([O-])([O-])[O-] JRPBQTZRNDNNOP-UHFFFAOYSA-N 0.000 description 1
- 229910002113 barium titanate Inorganic materials 0.000 description 1
- 239000003637 basic solution Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 150000001642 boronic acid derivatives Chemical class 0.000 description 1
- 239000004566 building material Substances 0.000 description 1
- YHWCPXVTRSHPNY-UHFFFAOYSA-N butan-1-olate;titanium(4+) Chemical compound [Ti+4].CCCC[O-].CCCC[O-].CCCC[O-].CCCC[O-] YHWCPXVTRSHPNY-UHFFFAOYSA-N 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000001877 deodorizing effect Effects 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 150000002013 dioxins Chemical class 0.000 description 1
- NJLLQSBAHIKGKF-UHFFFAOYSA-N dipotassium dioxido(oxo)titanium Chemical compound [K+].[K+].[O-][Ti]([O-])=O NJLLQSBAHIKGKF-UHFFFAOYSA-N 0.000 description 1
- 230000008034 disappearance Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 150000002222 fluorine compounds Chemical class 0.000 description 1
- XMBWDFGMSWQBCA-UHFFFAOYSA-N hydrogen iodide Chemical compound I XMBWDFGMSWQBCA-UHFFFAOYSA-N 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- ICIWUVCWSCSTAQ-UHFFFAOYSA-N iodic acid Chemical class OI(=O)=O ICIWUVCWSCSTAQ-UHFFFAOYSA-N 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- ZEIWWVGGEOHESL-UHFFFAOYSA-N methanol;titanium Chemical compound [Ti].OC.OC.OC.OC ZEIWWVGGEOHESL-UHFFFAOYSA-N 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000002808 molecular sieve Substances 0.000 description 1
- QQZOPKMRPOGIEB-UHFFFAOYSA-N n-butyl methyl ketone Natural products CCCCC(C)=O QQZOPKMRPOGIEB-UHFFFAOYSA-N 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 235000019645 odor Nutrition 0.000 description 1
- 150000002896 organic halogen compounds Chemical class 0.000 description 1
- 150000002903 organophosphorus compounds Chemical class 0.000 description 1
- 150000003891 oxalate salts Chemical class 0.000 description 1
- SOQBVABWOPYFQZ-UHFFFAOYSA-N oxygen(2-);titanium(4+) Chemical class [O-2].[O-2].[Ti+4] SOQBVABWOPYFQZ-UHFFFAOYSA-N 0.000 description 1
- CEOCDNVZRAIOQZ-UHFFFAOYSA-N pentachlorobenzene Chemical compound ClC1=CC(Cl)=C(Cl)C(Cl)=C1Cl CEOCDNVZRAIOQZ-UHFFFAOYSA-N 0.000 description 1
- 235000021317 phosphate Nutrition 0.000 description 1
- 150000003013 phosphoric acid derivatives Chemical class 0.000 description 1
- 238000013033 photocatalytic degradation reaction Methods 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 238000002459 porosimetry Methods 0.000 description 1
- 239000011736 potassium bicarbonate Substances 0.000 description 1
- 229910000028 potassium bicarbonate Inorganic materials 0.000 description 1
- 235000015497 potassium bicarbonate Nutrition 0.000 description 1
- 229910000027 potassium carbonate Inorganic materials 0.000 description 1
- 235000011181 potassium carbonates Nutrition 0.000 description 1
- TYJJADVDDVDEDZ-UHFFFAOYSA-M potassium hydrogencarbonate Chemical compound [K+].OC([O-])=O TYJJADVDDVDEDZ-UHFFFAOYSA-M 0.000 description 1
- 229940086066 potassium hydrogencarbonate Drugs 0.000 description 1
- 235000011118 potassium hydroxide Nutrition 0.000 description 1
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 description 1
- HKJYVRJHDIPMQB-UHFFFAOYSA-N propan-1-olate;titanium(4+) Chemical compound CCCO[Ti](OCCC)(OCCC)OCCC HKJYVRJHDIPMQB-UHFFFAOYSA-N 0.000 description 1
- 239000012495 reaction gas Substances 0.000 description 1
- 150000004760 silicates Chemical class 0.000 description 1
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 description 1
- 229910000030 sodium bicarbonate Inorganic materials 0.000 description 1
- 235000017557 sodium bicarbonate Nutrition 0.000 description 1
- 229910000029 sodium carbonate Inorganic materials 0.000 description 1
- 235000017550 sodium carbonate Nutrition 0.000 description 1
- 235000011121 sodium hydroxide Nutrition 0.000 description 1
- GROMGGTZECPEKN-UHFFFAOYSA-N sodium metatitanate Chemical compound [Na+].[Na+].[O-][Ti](=O)O[Ti](=O)O[Ti]([O-])=O GROMGGTZECPEKN-UHFFFAOYSA-N 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 230000001954 sterilising effect Effects 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 239000004094 surface-active agent Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 description 1
- 150000003608 titanium Chemical class 0.000 description 1
- JMXKSZRRTHPKDL-UHFFFAOYSA-N titanium ethoxide Chemical compound [Ti+4].CC[O-].CC[O-].CC[O-].CC[O-] JMXKSZRRTHPKDL-UHFFFAOYSA-N 0.000 description 1
- 230000001988 toxicity Effects 0.000 description 1
- 231100000419 toxicity Toxicity 0.000 description 1
- 238000002834 transmittance Methods 0.000 description 1
- 239000012808 vapor phase Substances 0.000 description 1
- 238000004065 wastewater treatment Methods 0.000 description 1
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- Inorganic Compounds Of Heavy Metals (AREA)
- Catalysts (AREA)
Description
この発明は、光触媒として用いられる酸化チタンの製造方法に係り、特にアナタース型結晶とルチル型結晶との比率が制御された光触媒酸化チタンを容易に製造することができる光触媒酸化チタンの製造方法に関する。 The present invention relates to a method for producing titanium oxide used as a photocatalyst, and more particularly to a method for producing photocatalytic titanium oxide that can easily produce photocatalytic titanium oxide in which the ratio of anatase type crystals and rutile type crystals is controlled .
近年、空気中に飛散する悪臭や有害物質を分解して除去したり、あるいは、排水処理や浄水処理等を行うための環境浄化材料として、更には、種々の基材の表面に優れた親水性を付与するための親水性付与剤として、温度、ｐＨ値、ガス雰囲気、毒性等の反応条件の制約が少なく、しかも、高活性で取扱が容易であることから、光触媒活性を有する酸化チタン（チタニア）が着目されており、例えば、アルデヒド、メルカプタン、アンモニア、各種のアミン類等の悪臭物質の分解脱臭、ＮＯX、ＳＯX、ＰＣＢ、ダイオキシン、有機ハロゲン化合物、有機リン化合物、界面活性剤等の有害物質の分解除去、各種の菌類や藻類等の殺菌・藻処理等の用途を始め、建築材料や土木材料等の親水性処理等の多くの用途に応用されている。 In recent years, as an environmental purification material for decomposing and removing bad odors and harmful substances scattered in the air, or for performing wastewater treatment, water purification treatment, etc., it has excellent hydrophilicity on the surface of various substrates. Titanium oxide (titania) with photocatalytic activity as a hydrophilicity-imparting agent for imparting photocatalytic activity because it has few restrictions on reaction conditions such as temperature, pH value, gas atmosphere and toxicity, and is highly active and easy to handle. ) are focused, for example, aldehydes, mercaptans, ammonia, decomposition deodorizing malodorous substances such as various amines, NO X, SO X, PCB, dioxins, organic halogen compounds, organic phosphorus compounds, such as a surfactant It has been applied to many uses such as decomposing and removing harmful substances, sterilizing various kinds of fungi and algae and treating algae, and hydrophilic treatments such as building materials and civil engineering materials.
そして、このような酸化チタンを工業的に製造する方法については、大別すると、精製した四塩化チタンの水溶液を高温（800〜1,000℃）の酸素雰囲気下に噴霧して四塩化チタンを酸化し、酸化チタン粒子を得る気相法と、水酸基を有する酸化チタン前駆体を製造してこの酸化チタン前駆体を熱処理する液相法とが知られている（清野 学著技報堂出版発行「酸化チタン−物性と応用技術」pp18-27(1991.6.25)）。 And about the method of manufacturing such a titanium oxide industrially, if it divides roughly, the aqueous solution of refined titanium tetrachloride will be sprayed in a high-temperature (800-1,000 degreeC) oxygen atmosphere, and titanium tetrachloride will be oxidized. The vapor phase method for obtaining titanium oxide particles and the liquid phase method for producing a titanium oxide precursor having a hydroxyl group and heat-treating the titanium oxide precursor are known (Titanium oxide- Physical properties and applied technology "pp18-27 (1991.6.25)).
しかしながら、前者の気相法においては、得られる製品が既に酸化チタン粒子であることから、光触媒として利用する際にその目的に応じて種々の剤形や形態に加工する、いわゆる二次加工が比較的し難いという問題があり、また、液相法においては、酸化チタン前駆体の状態で種々の剤形や形態に加工することができ、二次加工が比較的容易ではあるが、５００℃以上の高温で焼成する際には酸化チタン前駆体における酸化チタンの結晶形態が比較的光触媒活性の高いアナタース型から比較的光触媒活性の低いルチル型に転移し、これらアナタース型結晶とルチル型結晶の存在比率が変化し、焼成時に光触媒活性が低下するという問題がある。 However, in the former gas phase method, the product obtained is already titanium oxide particles, so when using it as a photocatalyst, so-called secondary processing, which is processed into various dosage forms and forms according to its purpose, is compared. In the liquid phase method, it can be processed into various dosage forms and forms in the state of a titanium oxide precursor, and secondary processing is relatively easy, but 500 ° C. or higher. When firing at a high temperature, the crystal form of titanium oxide in the titanium oxide precursor transitions from the anatase type with relatively high photocatalytic activity to the rutile type with relatively low photocatalytic activity, and the presence of these anatase type crystals and rutile type crystals There is a problem that the ratio changes and the photocatalytic activity decreases during firing.
ところで、酸化チタンが高い光触媒活性を発現する原因については必ずしも明らかではないが、純粋なアナタース型の酸化チタンと純粋なルチル型の酸化チタンとを用い、それぞれの混合割合を変えて触媒組成物を調製し、光触媒活性を評価した結果、アナタース型酸化チタンとルチル型酸化チタンとが混在し、その混合状態が光触媒活性を支配する重要な因子になっていることが報告されている（触媒 Vol.45, No.1, pp35-37(2003)）。
しかしながら、アナタース型結晶とルチル型結晶の比率が制御された酸化チタンを湿式法で工業的に製造するための方法については知られていない。
By the way, the cause of the high photocatalytic activity of titanium oxide is not necessarily clear, but pure anatase-type titanium oxide and pure rutile-type titanium oxide were used, and the mixing ratio was changed for each catalyst composition. As a result of preparing and evaluating photocatalytic activity, it has been reported that anatase-type titanium oxide and rutile-type titanium oxide are mixed, and the mixed state is an important factor governing photocatalytic activity (Catalyst Vol. 45, No. 1, pp35-37 (2003)).
However, there is no known method for industrially producing titanium oxide with a controlled ratio of anatase type crystal and rutile type crystal by a wet method.
そこで、本発明者らは、種々の剤形や形態に加工する際の二次加工が比較的容易であり、しかも、５００℃以上の温度で焼成した場合であってもアナタース型結晶とルチル型結晶との比率が制御された光触媒酸化チタンを容易に製造することができる手段について鋭意検討した結果、チタン含有酸性水溶液に塩基性水溶液を添加して水酸基を有する酸化チタン前駆体を析出させた後、得られた酸化チタン前駆体スラリー中に、酸性の原料水溶液を添加してｐＨ値を酸化チタン前駆体の溶解領域に降下させると共に原料を追加投入する操作と、この操作で得られたチタン含有酸性水溶液に塩基性水溶液を添加してｐＨ値を酸化チタン前駆体の析出領域に上昇させる操作とからなるｐＨスイング操作を少なくとも３回以上繰り返すことにより、単に二次加工が容易なだけでなく、５００℃以上の高温で焼成した際にアナタース型結晶とルチル型結晶との比率が制御された酸化チタンを容易に製造することができる酸化チタン前駆体が得られることを見出し、本発明を完成した。 Therefore, the present inventors are relatively easy to perform secondary processing when processing into various dosage forms and forms, and even when firing at a temperature of 500 ° C. or higher, anatase type crystals and rutile types As a result of intensive investigations on means for easily producing photocatalytic titanium oxide with a controlled ratio to the crystal, after adding a basic aqueous solution to a titanium-containing acidic aqueous solution to precipitate a titanium oxide precursor having a hydroxyl group In the obtained titanium oxide precursor slurry, an operation of adding an acidic raw material aqueous solution to lower the pH value to the dissolution region of the titanium oxide precursor and adding the raw material, and the titanium content obtained by this operation By repeating a pH swing operation consisting of adding an aqueous basic solution to an acidic aqueous solution and raising the pH value to the precipitation region of the titanium oxide precursor at least three times, In addition to easy secondary processing, a titanium oxide precursor capable of easily producing titanium oxide in which the ratio of anatase type crystal and rutile type crystal is controlled when baked at a high temperature of 500 ° C. or higher is obtained. The present invention has been completed.
従って、本発明の目的は、光触媒として用いる際に要求される種々の剤形や形態に二次加工することが容易であって、５００℃以上の高温で焼成してアナタース型結晶とルチル型結晶との比率が制御された光触媒酸化チタンを製造することができる光触媒酸化チタンの製造方法を提供することにある。 Therefore, an object of the present invention is to easily perform secondary processing into various dosage forms and forms required when used as a photocatalyst, and calcinate at a high temperature of 500 ° C. or higher to form anatase type crystals and rutile type crystals It is an object of the present invention to provide a photocatalytic titanium oxide production method capable of producing a photocatalytic titanium oxide with a controlled ratio.
また、本発明の他の目的は、上記の光触媒酸化チタンを製造するに際し、酸化チタン前駆体がその焼成前に光触媒として利用するのに必要な形状に二次加工される光触媒酸化チタンの製造方法を提供することにある。 Another object of the present invention is to produce a photocatalytic titanium oxide in which the titanium oxide precursor is secondarily processed into a shape necessary for use as a photocatalyst before firing when producing the photocatalytic titanium oxide. Is to provide.
すなわち、本発明は、チタン含有酸性水溶液に塩基性水溶液を添加して水酸基を有する酸化チタン前駆体を製造し、次いでこの酸化チタン前駆体を高温で焼成して光触媒酸化チタンを製造するに際し、上記酸化チタン前駆体の製造時には、チタン含有酸性水溶液に塩基性水溶液を添加して水酸基を有する酸化チタン前駆体を析出させた後、得られた酸化チタン前駆体スラリー中に、酸性の原料水溶液を添加してｐＨ値を酸化チタン前駆体の溶解領域に降下させると共に原料を追加投入する操作と、この操作で得られたチタン含有酸性水溶液に塩基性水溶液を添加してｐＨ値を酸化チタン前駆体の析出領域に上昇させる操作とからなるｐＨスイング操作を少なくとも３回以上７回以下の範囲で繰り返し、また、上記酸化チタン前駆体の焼成時には焼成温度５００℃以上６００℃以下の条件下に行い、上記酸化チタン前駆体製造時のｐＨスイング操作の回数と酸化チタン前駆体焼成時の温度及び時間とを制御することにより、アナタース型結晶（An）とルチル型結晶（Ru）との比率（An／Ru）が１．７〜１１．５の範囲内であって、BET表面積が４２m 2 /g以上である光触媒酸化チタンを製造することを特徴とする光触媒酸化チタンの製造方法である。 That is, the present invention provides a titanium oxide precursor having a hydroxyl group by adding a basic aqueous solution to a titanium-containing acidic aqueous solution, and then calcining the titanium oxide precursor at a high temperature to produce a photocatalytic titanium oxide. At the time of manufacturing the titanium oxide precursor, a basic aqueous solution is added to the titanium-containing acidic aqueous solution to precipitate a titanium oxide precursor having a hydroxyl group, and then the acidic raw material aqueous solution is added to the obtained titanium oxide precursor slurry. Then, the pH value is lowered to the dissolution region of the titanium oxide precursor and an additional raw material is added, and a basic aqueous solution is added to the titanium-containing acidic aqueous solution obtained by this operation to change the pH value of the titanium oxide precursor. the pH swing operation consisting of operations and to increase the deposition region at least repeated 3 times or more and 7 times or less in the range and, during firing of the titanium oxide precursor Anatase-type crystals (AnT) are produced by controlling the number of times of pH swing operation during the production of the titanium oxide precursor and the temperature and time during the firing of the titanium oxide precursor, under the conditions of a firing temperature of 500 ° C. to 600 ° C. ) And rutile-type crystals (Ru) (An / Ru) in the range of 1.7 to 11.5, and a photocatalytic titanium oxide having a BET surface area of 42 m 2 / g or more is produced. This is a method for producing photocatalytic titanium oxide .
また、本発明は、上記の光触媒酸化チタンを製造するに際し、酸化チタン前駆体がその焼成前に光触媒として利用するのに必要な形状に二次加工される光触媒酸化チタンの製造方法である。 In addition, the present invention is a method for producing photocatalytic titanium oxide, in which the titanium oxide precursor is secondarily processed into a shape necessary for use as a photocatalyst before firing when producing the photocatalytic titanium oxide .
更に、本発明は、上記の光触媒酸化チタンを製造するに際し、酸化チタン前駆体の製造時に、ｐＨ値を溶解領域に降下させる際の値が３．５以下であり、酸化チタン前駆体の析出領域のｐＨ値が７以上として合成される光触媒酸化チタンの製造方法である。 Further, in the production of the photocatalytic titanium oxide , the present invention has a value of 3.5 or less when the pH value is lowered to the dissolution region during the production of the titanium oxide precursor, and the precipitation region of the titanium oxide precursor. Is a method for producing photocatalytic titanium oxide synthesized with a pH value of 7 or more .
本発明において、酸化チタン前駆体を製造する際に用いられるチタン原料については、特に制限は無く、例えば、チタンの塩化物、弗化物、臭化物、ヨウ化物、硝酸塩、硫酸塩、炭酸塩、酢酸塩、燐酸塩、ホウ酸塩、蓚酸塩、フッ酸塩、ケイ酸塩、ヨウ素酸塩等のチタン塩、チタン酸、チタンのオキソ酸塩及びチタンのアルコキシド類等を挙げることができ、好ましいものとしては、例えば、四塩化チタン、硫酸チタン、硫酸チタニル、三塩化チタン、チタンメトキシド、チタンエトキシド、チタンプロポキシド、チタンイソプロポキシド、チタンテトライソプロポキシド、チタンテトラブトキシド、オルトチタン酸、メタチタン酸、四臭化チタン、四弗化チタン、三弗化チタン、チタン酸カリウム、チタン酸ナトリウム、チタン酸バリウム等を挙げることができる。これらのチタン原料は、その１種のみを単独で使用できるほか、２種以上の混合物として使用することもできる。 In the present invention, the titanium raw material used for producing the titanium oxide precursor is not particularly limited. For example, titanium chloride, fluoride, bromide, iodide, nitrate, sulfate, carbonate, acetate , Phosphates, borates, oxalates, fluorides, silicates, iodates, and other titanium salts, titanic acid, titanium oxoacid salts, and titanium alkoxides. For example, titanium tetrachloride, titanium sulfate, titanyl sulfate, titanium trichloride, titanium methoxide, titanium ethoxide, titanium propoxide, titanium isopropoxide, titanium tetraisopropoxide, titanium tetrabutoxide, orthotitanic acid, metatitanium Acid, titanium tetrabromide, titanium tetrafluoride, titanium trifluoride, potassium titanate, sodium titanate, barium titanate It can be mentioned. These titanium raw materials can be used alone or in a mixture of two or more.
また、この酸化チタン前駆体の製造に用いる酸性水溶液や塩基性水溶液としては、例えば、四塩化チタン、硫酸チタン、硫酸チタニル、三塩化チタン、四臭化チタン、四弗化チタン、三弗化チタン等の他に、硝酸、塩酸、硫酸等の酸性水溶液や、アンモニア、水酸化ナトリウム、水酸化カリウム、炭酸ナトリウム、炭酸カリウム、炭酸水素ナトリウム、炭酸水素カリウム等の塩基性水溶液を挙げることができ、これらの酸性水溶液及び塩基性水溶液についても、その１種のみを単独で使用できるほか、２種以上の混合物として使用することもできる。これらの酸性水溶液及び塩基性水溶液は、上記のチタン原料のみでは所定のｐＨ値に制御できない場合には、チタン原料と共に用いて、ｐＨ値を最適に制御することにも用いられる。 Examples of the acidic aqueous solution and basic aqueous solution used for the production of the titanium oxide precursor include titanium tetrachloride, titanium sulfate, titanyl sulfate, titanium trichloride, titanium tetrabromide, titanium tetrafluoride, titanium trifluoride. In addition to acid aqueous solutions such as nitric acid, hydrochloric acid, sulfuric acid, etc., basic aqueous solutions such as ammonia, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, etc. can be mentioned, These acidic aqueous solutions and basic aqueous solutions can also be used alone or in a mixture of two or more. These acidic aqueous solution and basic aqueous solution are used together with the titanium raw material to optimally control the pH value when the above-mentioned titanium raw material alone cannot be controlled to a predetermined pH value.
更に、酸化チタン前駆体を製造する際に用いる溶媒は、基本的には水であるが、特に制限されるものではなく、例えば、メタノール、エタノール、プロパノール、テトラヒドロフラン、アセトン、ジオキサン等の水溶性有機溶剤の水溶液等を用いることもできる。 Furthermore, the solvent used in producing the titanium oxide precursor is basically water, but is not particularly limited, and examples thereof include water-soluble organic substances such as methanol, ethanol, propanol, tetrahydrofuran, acetone, and dioxane. An aqueous solution of a solvent can also be used.
ここで、この酸化チタン前駆体を製造する際の反応条件については、製造時の水系溶媒中におけるチタン濃度が酸化チタン換算で通常０．１〜１５wt%、好ましくは０．５〜１０wt%であるのがよく、また、反応温度が常温から３００℃、好ましくは常温から１８０℃、より好ましくは常温から１００℃であり、また、反応圧力は原則的に常圧（０MPa）であり、使用する溶媒系と反応温度の条件下で液相を維持する圧力があれば十分である。 Here, regarding the reaction conditions for producing the titanium oxide precursor, the titanium concentration in the aqueous solvent at the time of production is usually 0.1 to 15 wt%, preferably 0.5 to 10 wt% in terms of titanium oxide. In addition, the reaction temperature is from room temperature to 300 ° C., preferably from room temperature to 180 ° C., more preferably from room temperature to 100 ° C., and the reaction pressure is basically normal pressure (0 MPa), and the solvent used It is sufficient to have a pressure that maintains the liquid phase under the conditions of the system and reaction temperature.
本発明においては、チタン含有酸性水溶液に塩基性水溶液を添加して水酸基を有する酸化チタン前駆体を析出させた後、得られた酸化チタン前駆体スラリー中に、酸性水溶液を添加してｐＨ値を酸化チタン前駆体の溶解領域に降下させると共に原料を追加投入する操作とこの操作で得られたチタン含有酸性水溶液に塩基性水溶液を添加してｐＨ値を酸化チタン前駆体の析出領域に上昇させる操作とからなるｐＨスイング操作を少なくとも３回以上、好ましくは５回以上、より好ましくは７回以上繰り返す必要がある。このｐＨスイングの繰返し回数が多いほど、５００℃以上で焼成した際のアナタース型結晶からルチル型結晶への転移が抑制され、得られた光触媒酸化チタンにおけるアナタース型結晶（An）とルチル型結晶（Ru）との比率（An／Ru）が大きくなり、また、粒子サイズが大きくなって細孔容積が大きくなる傾向がある。 In the present invention, after adding a basic aqueous solution to a titanium-containing acidic aqueous solution to precipitate a titanium oxide precursor having a hydroxyl group, the acidic aqueous solution is added to the resulting titanium oxide precursor slurry to adjust the pH value. An operation of lowering the titanium oxide precursor to the dissolution region and adding an additional raw material and an operation of adding a basic aqueous solution to the titanium-containing acidic aqueous solution obtained by this operation to raise the pH value to the precipitation region of the titanium oxide precursor It is necessary to repeat the pH swing operation consisting of: at least 3 times or more, preferably 5 times or more, more preferably 7 times or more. As the number of repetitions of this pH swing increases, the transition from the anatase type crystal to the rutile type crystal when fired at 500 ° C. or higher is suppressed, and the anatase type crystal (An) and the rutile type crystal ( The ratio (An / Ru) to Ru) increases, and the particle size tends to increase and the pore volume tends to increase.
ここで、具体的なｐＨスイング操作の方法は、チタン含有酸性水溶液に塩基性水溶液を添加して水酸基を有する酸化チタン前駆体を析出させ、得られた酸化チタン前駆体スラリー中に、酸性水溶液の添加と塩基性水溶液の添加とを交互に行って、酸化チタン前駆体の溶解領域であるｐＨ３．５以下、好ましくは０．５≦ｐＨ≦２．０と酸化チタン前駆体の析出領域であるｐＨ７以上、好ましくは７．０≦ｐＨ≦８．５との間をスイングさせるものである。また、酸性水溶液の添加後には微細な粒子が溶解消失するに十分な時間、通常３〜６０分、好ましくは５〜２０分間保持し、塩基性水溶液の添加後には粒子成長に十分な熟成時間、通常３〜３０分、好ましくは５〜１５分間保持して熟成時間を設けるのがよい。 Here, a specific method of pH swing operation is to add a basic aqueous solution to a titanium-containing acidic aqueous solution to precipitate a titanium oxide precursor having a hydroxyl group, and in the obtained titanium oxide precursor slurry, The addition of the basic aqueous solution and the addition of the basic aqueous solution are alternately performed to have a pH of 3.5 or less, preferably 0.5 ≦ pH ≦ 2.0, which is a dissolution region of the titanium oxide precursor, and a pH of 7 which is a precipitation region of the titanium oxide precursor. As mentioned above, Preferably it is made to swing between 7.0 <= pH <= 8.5. Also, after the addition of the acidic aqueous solution, it is held for a time sufficient for dissolution and disappearance of fine particles, usually 3 to 60 minutes, preferably 5 to 20 minutes, and after the addition of the basic aqueous solution, an aging time sufficient for particle growth, Usually, the aging time is set by holding for 3 to 30 minutes, preferably 5 to 15 minutes.
本発明の酸化チタン前駆体は、上記のｐＨスイング操作によって得られた酸化チタン前駆体スラリーをろ過し、必要により脱水・乾燥し、また、必要により洗浄して得られるものであり、この際に、酸化チタン前駆体を固形物基準で含水量１０〜２００wt%、好ましくは５０〜１００wt%にまで脱水あるいは乾燥され、必要により洗浄を行う場合は、湿潤ケーキを再度水に分散して濾過する操作を繰り返すことによって洗浄することができる。洗浄の際は、この操作を好ましくは１〜３回繰り返すことで合成時に生じた水酸化チタン以外の化合物を除去することができる。こうして得られた酸化チタン前駆体は、次いで光触媒として用いる際に要求される種々の剤形や形態に二次加工される。 The titanium oxide precursor of the present invention is obtained by filtering the titanium oxide precursor slurry obtained by the above pH swing operation, dehydrating and drying if necessary, and washing if necessary. When the titanium oxide precursor is dehydrated or dried to a water content of 10 to 200 wt%, preferably 50 to 100 wt% on a solid basis, and if necessary, the wet cake is dispersed again in water and filtered. Can be washed by repeating the above. In washing, this operation is preferably repeated 1 to 3 times to remove compounds other than titanium hydroxide produced during the synthesis. The titanium oxide precursor thus obtained is then subjected to secondary processing into various dosage forms and forms required for use as a photocatalyst.
この酸化チタン前駆体の二次加工については、特に制限されるものではなく、例えば、湿潤ケーキのまま所望の形状に成形して焼成する方法や、湿潤ケーキを所望の濃度に水等の溶媒中に分散させて塗布した後に焼成する方法等を例示することができ、これらの使用形態は応用される製品の必要に応じて様々な形態で利用することが可能である。 The secondary processing of the titanium oxide precursor is not particularly limited. For example, the wet cake is molded into a desired shape and fired, or the wet cake is dissolved in a solvent such as water to a desired concentration. Examples of the method of firing after being dispersed and applied can be exemplified, and these usage forms can be used in various forms according to the needs of the products to be applied.
このように二次加工して得られた光触媒用酸化チタン前駆体は、次に、更に温度４０〜３５０℃、好ましくは８０〜１２０℃で０．５〜２４時間、好ましくは０．５〜５時間乾燥した後、温度１２０〜１，０００℃、好ましくは５００〜８００℃で０．５〜４８時間、好ましくは１〜５時間焼成され、光触媒として用いる酸化チタンとされる。この焼成温度については、高くなればなるほどアナタース型結晶（An）がルチル型結晶（Ru）に転移し、アナタース型結晶（An）とルチル型結晶（Ru）との比率（An／Ru）が低下する傾向があるので、光触媒酸化チタンとして望まれるアナタース型結晶（An）とルチル型結晶（Ru）との比率（An／Ru）に応じて、適当な焼成温度と時間を選択するのがよい。 The titanium oxide precursor for photocatalyst thus obtained by secondary processing is then further heated at a temperature of 40 to 350 ° C., preferably 80 to 120 ° C. for 0.5 to 24 hours, preferably 0.5 to 5 After drying for a period of time, it is calcined at a temperature of 120 to 1,000 ° C., preferably 500 to 800 ° C. for 0.5 to 48 hours, preferably 1 to 5 hours, to obtain titanium oxide used as a photocatalyst. About this firing temperature, the higher the anatase type crystal (An), the more the anatase type crystal (An) is transferred to the rutile type crystal (Ru), and the lower the ratio (An / Ru) of the anatase type crystal (An) to the rutile type crystal (Ru). Therefore, it is preferable to select an appropriate firing temperature and time according to the ratio (An / Ru) of anatase type crystal (An) and rutile type crystal (Ru) desired as photocatalytic titanium oxide.
本発明により、アナタース型結晶（An）とルチル型結晶（Ru）との比率（An／Ru）が５０%以上で高い光触媒活性を有する酸化チタンを製造する場合には、ｐＨスイングの繰返し数を５回以上、好ましくは７回以上とするのがよく、また、焼成温度については更に好ましくは５５０〜８００℃とするのがよい。 According to the present invention, when producing titanium oxide having a high photocatalytic activity at a ratio (An / Ru) of anatase type crystal (An) to rutile type crystal (Ru) of 50% or more, the number of repetitions of pH swing is set. 5 times or more, preferably 7 times or more, and the firing temperature is more preferably 550 to 800 ° C.
本発明の光触媒酸化チタンの製造方法によれば、光触媒として用いる際に要求される種々の剤形や形態に二次加工することが容易であるだけでなく、その製造時のｐＨスイング操作の繰返し数と、５００℃以上の高温で焼成する際の温度によってアナタース型結晶とルチル型結晶との比率が制御された光触媒酸化チタンを工業的に容易に製造することができ、ひいては所望の光触媒活性を有する酸化チタンを工業的に容易に製造することができる。 According to the manufacturing method of the titanium oxide photocatalyst of the present invention, not only it is easy to be fabricated into a variety of dosage forms and forms are required when used as a photocatalyst, the repetition of pH swing operation at the time of manufacture The photocatalytic titanium oxide in which the ratio of the anatase type crystal and the rutile type crystal is controlled according to the number and the temperature when firing at a high temperature of 500 ° C. or higher can be easily produced industrially, and thus has a desired photocatalytic activity. The titanium oxide having it can be easily produced industrially.
以下、実施例（実験例及び試験例）に基づいて、本発明の好適な実施の形態を具体的に説明する。 Hereinafter, preferred embodiments of the present invention will be specifically described based on examples (experimental examples and test examples).
〔実験例１〜２７〕
純水で製造した氷を粉砕して容器に入れ、この容器内に四塩化チタン(TiCl4)５００gを添加して粉砕した氷と混合し、更に容器内に純水を添加して溶液全体を１，０００mlとし、四塩化チタン水溶液（溶液Ａ）を調製した。
また、28wt%-アンモニア水を同量の純水で希釈し、14wt%-アンモニア水（溶液Ｂ）を調製した。
[Experimental Examples 1 to 27]
Ice made with pure water is crushed and placed in a container, 500 g of titanium tetrachloride (TiCl 4 ) is added to this container and mixed with crushed ice, and pure water is further added to the container to complete the entire solution. The solution was made up to 1,000 ml, and an aqueous titanium tetrachloride solution (solution A) was prepared.
Further, 28 wt% -ammonia water was diluted with the same amount of pure water to prepare 14 wt% -ammonia water (solution B).
次に、３５Lの反応容器に純水２０Lを入れて７５℃まで加熱し、更に撹拌下に上記溶液Ａの５００mlを添加して混合した。得られた溶液のｐＨ値は１．１であった。
続いて、反応容器中には撹拌下に上記溶液Ｂの７１０mlを一度に添加した。得られた溶液はｐＨ値８．５となり、この操作により溶液中に酸化チタン前駆体が析出し、溶液はスラリー状になった。
Next, 20 L of pure water was put into a 35 L reaction vessel and heated to 75 ° C., and 500 ml of the above solution A was added and mixed with stirring. The pH value of the obtained solution was 1.1.
Subsequently, 710 ml of the above solution B was added to the reaction vessel at a time with stirring. The resulting solution had a pH value of 8.5. By this operation, a titanium oxide precursor was precipitated in the solution, and the solution became a slurry.
このようにして得られた酸化チタン前駆体スラリーに、撹拌下に５００mlの溶液Ａを添加し、ｐＨ値を１．１に低下させて５分間保持し、次いで撹拌下に７２０mlの溶液Ｂを添加し、ｐＨ値を８．５に上昇させて５分間保持するｐＨスイング操作を表１に示す回数だけ繰り返し、酸化チタン前駆体スラリーを得た。 To the titanium oxide precursor slurry thus obtained, 500 ml of solution A is added under stirring, the pH value is lowered to 1.1 and held for 5 minutes, and then 720 ml of solution B is added under stirring. Then, the pH swing operation in which the pH value was raised to 8.5 and held for 5 minutes was repeated as many times as shown in Table 1 to obtain a titanium oxide precursor slurry.
各実験例１〜２７の酸化チタン前駆体スラリーを濾過し、酸化チタン前駆体の湿潤ケーキを得た後、各湿潤ケーキをそれぞれ２０Lの純水中に分散させて３０分間撹拌した後再び濾過する洗浄操作を３回実施し、湿潤ケーキ中に残存する塩化アンモニウムを除去した。
得られた各実験例１〜２７の湿潤ケーキを１２０℃で３時間乾燥し、各実験例１〜２７の酸化チタン前駆体を得た。
The titanium oxide precursor slurry of each experimental example 1 to 27 was filtered to obtain a wet cake of the titanium oxide precursor, then each wet cake was dispersed in 20 L of pure water, stirred for 30 minutes, and then filtered again. The washing operation was performed three times to remove ammonium chloride remaining in the wet cake.
The obtained wet cakes of Experimental Examples 1 to 27 were dried at 120 ° C. for 3 hours to obtain titanium oxide precursors of Experimental Examples 1 to 27.
〔試験例１〕
上記実験例１〜２７で得られた各酸化チタン前駆体について、空気流通下にそれぞれ表１に示す温度及び時間の条件で焼成し、冷却した後に粉砕して酸化チタン粉末を得た。
[Test Example 1]
About each titanium oxide precursor obtained in the said Experimental Examples 1-27, it baked on the conditions of the temperature and time which are respectively shown in Table 1 under air circulation, cooled, and it grind | pulverized, and obtained titanium oxide powder.
得られた各実験例１〜２７の光触媒酸化チタンについて、窒素吸着によりＢＥＴ表面積(m2/g)を測定すると共に、水銀圧入法ポロシメトリーにより細孔分布測定〔細孔容積(cc/g)及び平均細孔径(nm)〕を行い、更にＸ線回折計（PHLIPS社製XPERT SYSTEM/APD-1700）を用いてＸ線回折(XRD)パターンを測定し、各酸化チタン粉末中におけるアナタース型結晶（An）の最強干渉ピークの強度IAnとルチル型結晶（Ru）の最強干渉ピークの強度IRuから、一般的に用いられる次の（１）式からアナタース型結晶の含有量（重量%）を求め、アナタース型結晶の含有量とルチル型結晶の含有量の和を１００としてルチル型結晶の含有量を求めた。またこれらから、アナタース型結晶の比率（An／Ru）を計算した。
アナタース型結晶含有率（重量%）=100／[1+1.265(IRu/IAn)]……（１）
これらの結果を表１に示す。これより、１２０℃乾燥品及び４００℃焼成品についてはルチル型結晶がみられないが、５００℃以上の焼成温度ではルチル型結晶が検出されることがわかる。
The obtained photocatalytic titanium oxides of Experimental Examples 1 to 27 were measured for BET surface area (m 2 / g) by nitrogen adsorption and pore distribution measurement by mercury porosimetry (pore volume (cc / g)). And the average pore diameter (nm)], and then measuring the X-ray diffraction (XRD) pattern using an X-ray diffractometer (XPERT SYSTEM / APD-1700 manufactured by PHLIPS), and anatase crystals in each titanium oxide powder the content of anatase-type crystal from the strongest interference intensity peak I Ru intensity I an and rutile-type crystal of the strongest interference peaks (Ru), typically from the following used (1) of the (an) (wt%) The content of the rutile crystal was determined by taking the sum of the content of the anatase crystal and the content of the rutile crystal as 100. From these, the ratio of anatase type crystals (An / Ru) was calculated.
Anatase type crystal content (wt%) = 100 / [1 + 1.265 (I Ru / I An )] …… (1)
These results are shown in Table 1. From this, it can be seen that no rutile crystals are observed in the 120 ° C. dried product and the 400 ° C. fired product, but the rutile crystals are detected at a firing temperature of 500 ° C. or higher.
〔試験例２〕
〔３時間焼成時の５００℃及び６００℃におけるスイング回数による結晶転移の抑制効果〕
図１にスイング回数を７回（実験例２２）、１０回（実験例２３）、及び１５回（実験例２４）として合成した前駆体ゲルの５００℃、３時間焼成時のＸ線回折パターンを示す。スイング回数が多くなるにつれてルチル型結晶のピーク強度が小さくなり、結晶転移が抑制されていることがわかる。また、図２にこれらの前駆体ゲル〔スイング回数が７回（実験例２５）、１０回（実験例２６）、及び１５回（実験例２７）〕を６００℃、３時間焼成した場合のＸ線回折パターンを示す。図１の５００℃焼成の場合と同様にスイング回数が多くなるにつれてルチル型結晶のピーク強度が小さくなり、結晶転移が抑制されていることがわかるが、焼成温度が６００℃で５００℃に比べて高温のため、ルチル型結晶のピーク強度が図１に比べて大きくなっていることが観察される。
[Test Example 2]
[Suppression effect of crystal transition due to the number of swings at 500 ° C. and 600 ° C. during firing for 3 hours]
FIG. 1 shows the X-ray diffraction pattern of the precursor gel synthesized with the number of swings of 7 times (Experimental Example 22), 10 times (Experimental Example 23), and 15 times (Experimental Example 24) at 500 ° C. for 3 hours. Show. As the number of swings increases, the peak intensity of the rutile crystal decreases, indicating that the crystal transition is suppressed. FIG. 2 shows X when the precursor gels were baked at 600 ° C. for 3 hours (7 swings (Experiment 25), 10 (Experiment 26), and 15 (Experiment 27)). A line diffraction pattern is shown. As in the case of 500 ° C. firing in FIG. 1, the peak intensity of the rutile crystal decreases as the number of swings increases, and the crystal transition is suppressed, but the firing temperature is 600 ° C. compared to 500 ° C. It is observed that the peak intensity of the rutile crystal is higher than that in FIG. 1 due to the high temperature.
〔試験例３〕
〔４０時間焼成時の６００℃におけるスイング回数による結晶転移の抑制効果〕
図３にスイング回数を３回（実験例１９）、５回（実験例２０）、７回（実験例２１）として合成した前駆体ゲルの６００℃、４０時間焼成時のＸ線回折パターンを示す。４０時間焼成した場合でも３回または５回のスイングによって合成した前駆体に比べて７回スイングによって合成した前駆体は、アナタース型結晶のピークが大きく残留しており、結晶転移が抑制されていることがわかる。
[Test Example 3]
[Suppression effect of crystal transition due to the number of swings at 600 ° C. during firing for 40 hours]
FIG. 3 shows an X-ray diffraction pattern of the precursor gel synthesized with 3 swings (Experimental Example 19), 5 (Experimental Example 20), and 7 (Experimental Example 21) when calcined at 600 ° C. for 40 hours. . Even when it is baked for 40 hours, the precursor synthesized by the 7th swing compared with the precursor synthesized by the 3rd or 5th swing has a large anatase-type crystal peak, and the crystal transition is suppressed. I understand that.
〔試験例４〕
〔2-プロパノール光触媒分解反応試験（液相試験）〕
また、上記各酸化チタン粉末について、下記の2-プロパノール光触媒分解反応試験（液相試験）を行い、光触媒活性を調べた。
耐熱性と光透過性に優れた直径２cm×長さ２０cmの大きさの石英ガラス製反応セル内に上記各実験例１〜２１の光触媒酸化チタン５０mgと2-プロパノール水溶液又は2-ヘキサノール水溶液２５ml（65μmol）を入れ、酸素を３０分間バブリングした後（酸素雰囲気下）、撹拌して懸濁させながら室温下に１時間光照射し、2-プロパノールの減少率(%)を求めた。この際に、反応セルにはその上部にラバーセプタム（直径2.1cm）を取り付け、また、光照射は、光源の高圧水銀灯（100W）を反応セルから約６cm離して〔デジタル照度計（東京光電社製LX-1330）を高圧水銀灯に対して平行に設置して測定した時の照度が約6150Lux〕行った。
表１に反応開始１時間後における2-プロパノールの分解率（%）を示す。
[Test Example 4]
[2-propanol photocatalytic degradation test (liquid phase test)]
Moreover, about each said titanium oxide powder, the following 2-propanol photocatalytic decomposition reaction test (liquid phase test) was done, and photocatalytic activity was investigated.
In a quartz glass reaction cell having a diameter of 2 cm and a length of 20 cm excellent in heat resistance and light transmittance, 50 mg of the photocatalytic titanium oxide of each of the above experimental examples 1 to 21 and 25 ml of 2-propanol aqueous solution or 2-hexanol
Table 1 shows the decomposition rate (%) of 2-propanol one hour after the start of the reaction.
〔試験例５〕
〔ＮＯ光触媒分解反応試験（気相試験）〕
また、上記各酸化チタン粉末について、下記のＮＯ光触媒分解反応試験（気相試験）を行い、光触媒活性を調べた。
上記と同様の反応セル（容量：73.3cm3）内に上記各実験例１〜２１の光触媒酸化チタン１００mgを入れ、大気中で吸着水の多くが脱離する５２３Kまで徐々に昇温させ、更に７２３Kまで昇温させた後、同温度で３時間排気させた。酸素処理は液体窒素トラップで精製した酸素を接触部に２０Torr以上導入し、７２３Kで２時間行った。その後、室温に戻し、再びゆっくりと４７３Kまで昇温させ、同温度で２時間排気した。
[Test Example 5]
[NO photocatalytic decomposition reaction test (gas phase test)]
Moreover, about the said each titanium oxide powder, the following NO photocatalyst decomposition reaction test (gas phase test) was done, and photocatalytic activity was investigated.
In a reaction cell similar to the above (capacity: 73.3 cm 3 ), 100 mg of the photocatalytic titanium oxide of each of the above experimental examples 1 to 21 was gradually heated up to 523 K from which most of the adsorbed water was desorbed in the atmosphere. The temperature was raised to 723 K, and then evacuated at the same temperature for 3 hours. Oxygen treatment was performed at 723 K for 2 hours by introducing 20 Torr or more of oxygen purified by a liquid nitrogen trap into the contact portion. Thereafter, the temperature was returned to room temperature, the temperature was slowly raised again to 473 K, and evacuation was performed at the same temperature for 2 hours.
以上の前処理をした後、反応セル内に反応ガスであるＮＯを５Torrの圧になるまで導入し、２７５Kで光触媒酸化チタンに紫外光（UV-27フィルター使用；λ＞270nm）を照射し、未反応物のＮＯや反応生成物であるＮ2Ｏを液体窒素でトラップしてガスクロマトグラフィー（島津製作所社製GC-12A,14A；Porapack Q+S,2m+2m）で定性及び定量し、また、トラップされない反応生成物のＮ2とＯ2をガスクロマトグラフィー（島津製作所社製GC-12A,14A；モレキュラーシーブ5A,6m）で定性及び定量し、１μmol中に生成したＮ2とＮ2Ｏの量を求めた。
結果を表１に示す。
After the above pretreatment, NO, which is a reaction gas, is introduced into the reaction cell until a pressure of 5 Torr is reached, and photocatalytic titanium oxide is irradiated with ultraviolet light (using a UV-27 filter; λ> 270 nm) at 275K. Unreacted NO and reaction product N 2 O are trapped with liquid nitrogen and qualitatively and quantified by gas chromatography (Shimadzu Corporation GC-12A, 14A; Porapack Q + S, 2m + 2m) Further, N 2 and O 2 of the reaction product which is not trapped are qualitatively and quantitatively analyzed by gas chromatography (GC-12A, 14A, manufactured by Shimadzu Corporation; molecular sieve 5A, 6m), and N 2 and N 2 produced in 1 μmol. The amount of O was determined.
The results are shown in Table 1.
〔試験例６〕
実験例３及び７の各酸化チタン前駆体から得られた酸化チタン粉末を用い、上記2-プロパノール光触媒分解反応試験（液相試験）において2-プロパノールが完全に炭酸ガス（CO2）に分解されるまでの経時変化を測定し、市販の光触媒酸化チタン粉末〔JRC-TIO-4（P-25）〕（比較例１）と比較した。
結果を図４〜図６に示す。
[Test Example 6]
Using the titanium oxide powder obtained from each titanium oxide precursor of Experimental Examples 3 and 7, 2-propanol was completely decomposed into carbon dioxide (CO 2 ) in the 2-propanol photocatalytic decomposition reaction test (liquid phase test). The time-dependent change until this time was measured and compared with a commercially available photocatalytic titanium oxide powder [JRC-TIO-4 (P-25)] (Comparative Example 1).
The results are shown in FIGS.
表１に示す結果から明らかなように、ｐＨスイングの繰返し回数が多くなればなるほど、５００℃以上で焼成して得られる光触媒酸化チタンにおけるアナタース型結晶（An）とルチル型結晶（Ru）との比率（An／Ru）が大きくなり、比較的高い光触媒活性が発現する。また、焼成温度が高くなるにつれてアナタース型結晶（An）がルチル型結晶（Ru）に転移してルチル型結晶の比率が高くなり、光触媒活性も低下する傾向がある。 As is clear from the results shown in Table 1, as the number of repetitions of the pH swing increases, the anatase type crystal (An) and the rutile type crystal (Ru) in the photocatalytic titanium oxide obtained by baking at 500 ° C. or higher are obtained. The ratio (An / Ru) increases and a relatively high photocatalytic activity is exhibited. Further, as the firing temperature is increased, the anatase type crystal (An) is transferred to the rutile type crystal (Ru), the ratio of the rutile type crystal is increased, and the photocatalytic activity tends to be decreased.
本発明の光触媒酸化チタンの製造方法によれば、単に光触媒として用いる際に要求される種々の剤形や形態に二次加工することが容易であるばかりでなく、５００℃以上の高温で焼成してアナタース型結晶とルチル型結晶との比率が制御され、結果として光触媒活性が制御された光触媒酸化チタンを工業的に容易に製造することができる。 According to the method for producing photocatalytic titanium oxide of the present invention, it is not only easy to secondary-process into various dosage forms and forms required when used as a photocatalyst, but also calcined at a high temperature of 500 ° C. or higher. Thus, the ratio of the anatase type crystal to the rutile type crystal is controlled, and as a result, the photocatalytic titanium oxide with controlled photocatalytic activity can be easily produced industrially.
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