JP2008149312A - Visible light responsive photocatalyst, catalytic activity accelerator of the same, and photolysis method of environmental pollution organic substance - Google Patents
Visible light responsive photocatalyst, catalytic activity accelerator of the same, and photolysis method of environmental pollution organic substance Download PDFInfo
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- 239000011941 photocatalyst Substances 0.000 title claims abstract description 110
- 239000000126 substance Substances 0.000 title claims abstract description 31
- 238000000034 method Methods 0.000 title claims abstract description 15
- 238000006303 photolysis reaction Methods 0.000 title claims abstract description 14
- 230000015843 photosynthesis, light reaction Effects 0.000 title claims abstract description 10
- 230000003197 catalytic effect Effects 0.000 title abstract description 14
- 238000003912 environmental pollution Methods 0.000 title abstract 3
- 239000005749 Copper compound Substances 0.000 claims abstract description 52
- 150000001880 copper compounds Chemical class 0.000 claims abstract description 46
- QPLDLSVMHZLSFG-UHFFFAOYSA-N Copper oxide Chemical compound [Cu]=O QPLDLSVMHZLSFG-UHFFFAOYSA-N 0.000 claims abstract description 35
- 239000003054 catalyst Substances 0.000 claims abstract description 26
- 150000001875 compounds Chemical class 0.000 claims abstract description 10
- ARUVKPQLZAKDPS-UHFFFAOYSA-L copper(II) sulfate Chemical compound [Cu+2].[O-][S+2]([O-])([O-])[O-] ARUVKPQLZAKDPS-UHFFFAOYSA-L 0.000 claims abstract description 9
- 229910000365 copper sulfate Inorganic materials 0.000 claims abstract description 6
- 150000003658 tungsten compounds Chemical group 0.000 claims abstract description 5
- 239000000843 powder Substances 0.000 claims description 50
- QGLKJKCYBOYXKC-UHFFFAOYSA-N nonaoxidotritungsten Chemical compound O=[W]1(=O)O[W](=O)(=O)O[W](=O)(=O)O1 QGLKJKCYBOYXKC-UHFFFAOYSA-N 0.000 claims description 30
- 229910001930 tungsten oxide Inorganic materials 0.000 claims description 30
- 230000000694 effects Effects 0.000 claims description 25
- 239000003344 environmental pollutant Substances 0.000 claims description 16
- 239000010409 thin film Substances 0.000 claims description 10
- XTVVROIMIGLXTD-UHFFFAOYSA-N copper(II) nitrate Chemical compound [Cu+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O XTVVROIMIGLXTD-UHFFFAOYSA-N 0.000 claims description 4
- 239000005751 Copper oxide Substances 0.000 claims description 3
- 229910000431 copper oxide Inorganic materials 0.000 claims description 3
- 150000001732 carboxylic acid derivatives Chemical class 0.000 claims 1
- 125000002485 formyl group Chemical class [H]C(*)=O 0.000 claims 1
- 230000001699 photocatalysis Effects 0.000 abstract description 17
- -1 copper (II) nitride Chemical class 0.000 abstract description 10
- 230000009471 action Effects 0.000 abstract description 6
- 230000001737 promoting effect Effects 0.000 abstract description 3
- BERDEBHAJNAUOM-UHFFFAOYSA-N copper(i) oxide Chemical compound [Cu]O[Cu] BERDEBHAJNAUOM-UHFFFAOYSA-N 0.000 abstract 2
- 230000001502 supplementing effect Effects 0.000 abstract 1
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 94
- 239000001569 carbon dioxide Substances 0.000 description 47
- 229910002092 carbon dioxide Inorganic materials 0.000 description 47
- IKHGUXGNUITLKF-UHFFFAOYSA-N Acetaldehyde Chemical compound CC=O IKHGUXGNUITLKF-UHFFFAOYSA-N 0.000 description 34
- 230000000052 comparative effect Effects 0.000 description 21
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 12
- 150000001299 aldehydes Chemical class 0.000 description 11
- 150000001735 carboxylic acids Chemical class 0.000 description 11
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 10
- 238000000354 decomposition reaction Methods 0.000 description 10
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 10
- 239000010949 copper Substances 0.000 description 9
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 description 8
- 238000002474 experimental method Methods 0.000 description 7
- 238000004519 manufacturing process Methods 0.000 description 7
- 239000004065 semiconductor Substances 0.000 description 7
- 238000001782 photodegradation Methods 0.000 description 6
- 239000007789 gas Substances 0.000 description 5
- 239000007788 liquid Substances 0.000 description 5
- 239000004570 mortar (masonry) Substances 0.000 description 5
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 description 4
- 229910021591 Copper(I) chloride Inorganic materials 0.000 description 4
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 4
- 230000008859 change Effects 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- OXBLHERUFWYNTN-UHFFFAOYSA-M copper(I) chloride Chemical compound [Cu]Cl OXBLHERUFWYNTN-UHFFFAOYSA-M 0.000 description 4
- 235000019253 formic acid Nutrition 0.000 description 4
- 238000011068 loading method Methods 0.000 description 4
- 238000002156 mixing Methods 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 3
- YMWUJEATGCHHMB-UHFFFAOYSA-N Dichloromethane Chemical compound ClCCl YMWUJEATGCHHMB-UHFFFAOYSA-N 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 3
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 description 3
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 description 3
- 229910052802 copper Inorganic materials 0.000 description 3
- 238000004817 gas chromatography Methods 0.000 description 3
- 229910044991 metal oxide Inorganic materials 0.000 description 3
- 150000004706 metal oxides Chemical class 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 230000001590 oxidative effect Effects 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 2
- XHCLAFWTIXFWPH-UHFFFAOYSA-N [O-2].[O-2].[O-2].[O-2].[O-2].[V+5].[V+5] Chemical compound [O-2].[O-2].[O-2].[O-2].[O-2].[V+5].[V+5] XHCLAFWTIXFWPH-UHFFFAOYSA-N 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 229910000416 bismuth oxide Inorganic materials 0.000 description 2
- TYIXMATWDRGMPF-UHFFFAOYSA-N dibismuth;oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Bi+3].[Bi+3] TYIXMATWDRGMPF-UHFFFAOYSA-N 0.000 description 2
- 238000005470 impregnation Methods 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 229910003437 indium oxide Inorganic materials 0.000 description 2
- PJXISJQVUVHSOJ-UHFFFAOYSA-N indium(iii) oxide Chemical compound [O-2].[O-2].[O-2].[In+3].[In+3] PJXISJQVUVHSOJ-UHFFFAOYSA-N 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 230000031700 light absorption Effects 0.000 description 2
- 230000004298 light response Effects 0.000 description 2
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- 229910052760 oxygen Inorganic materials 0.000 description 2
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- 229910001935 vanadium oxide Inorganic materials 0.000 description 2
- 230000032900 absorption of visible light Effects 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- IKHGUXGNUITLKF-XPULMUKRSA-N acetaldehyde Chemical compound [14CH]([14CH3])=O IKHGUXGNUITLKF-XPULMUKRSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 150000001350 alkyl halides Chemical class 0.000 description 1
- 150000001491 aromatic compounds Chemical class 0.000 description 1
- 238000004774 atomic orbital Methods 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- ORTQZVOHEJQUHG-UHFFFAOYSA-L copper(II) chloride Chemical compound Cl[Cu]Cl ORTQZVOHEJQUHG-UHFFFAOYSA-L 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 238000007606 doctor blade method Methods 0.000 description 1
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- SVHYQQLGPHVQFY-UHFFFAOYSA-N iron;oxotungsten Chemical compound [Fe].[W]=O SVHYQQLGPHVQFY-UHFFFAOYSA-N 0.000 description 1
- 150000002576 ketones Chemical class 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
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- 229910052757 nitrogen Inorganic materials 0.000 description 1
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Abstract
Description
本発明は可視光応答性光触媒とその触媒活性促進剤、そしてこの促進剤を併用した可視光応答性光触媒を用いる環境汚染有機物質の光分解法に関するものである。 The present invention relates to a visible light responsive photocatalyst, a catalyst activity promoter thereof, and a method for photodegrading an environmental pollutant organic substance using a visible light responsive photocatalyst using the accelerator in combination.
近年、環境汚染物質を吸着し太陽光や室内光によって分解除去する光触媒が注目され、その研究が精力的に行われている。酸化チタンはその代表的なものであり強力な光触媒活
性を示す。
In recent years, photocatalysts that adsorb environmental pollutants and decompose and remove them with sunlight or room light have attracted attention, and their research has been conducted energetically. Titanium oxide is a typical example and exhibits strong photocatalytic activity.
しかし、この酸化チタンはバンドギャップが大きく、紫外光には活性を示すが太陽光の大部分を占める可視光には吸収性がなく、可視光に対する触媒活性を示さないため、太陽光を十分に利用することができず、また紫外光が極めて弱い室内では機能しないことなどの問題があった。 However, this titanium oxide has a large band gap and is active in ultraviolet light, but is not absorbing in visible light, which occupies most of sunlight, and does not show catalytic activity for visible light. There is a problem that it cannot be used and does not function in a room where ultraviolet light is extremely weak.
このための対策として、窒素ドープなどで可視光を吸収できるようにするなどの酸化チタンの改良研究や可視光で光触媒として活性を示す新規な酸化物半導体の探索研究などが行われている（例えば、非特許文献１、２）。
As countermeasures for this, improvement research of titanium oxide, such as allowing visible light to be absorbed by nitrogen doping or the like, research for searching for a new oxide semiconductor that exhibits activity as a photocatalyst by visible light, and the like have been carried out (for example, Non-patent
たとえば、酸化チタンに比較してバンドギャップが小さいために可視光を吸収することができる、酸化タングステン、酸化鉄、酸化インジウム、酸化バナジウム、酸化ビスマスなどの半導体化合物（金属酸化物）は可視光活性な光触媒（可視光応答性光触媒）として期待されている。これらの半導体化合物では酸素の原子軌道による価電子帯への寄与が大きく、金属が異なっても価電子帯の位置はほとんど変化しない。バンドギャップが小さいのは伝導帯下端の位置が低くなったためである。この場合、バンドギャップが小さく可視光応答性であったとしても電子励起で価電子帯に生成する正孔は吸着した基質に対する酸化力を減少することはない。（一方、上記した窒素ドープ酸化チタンの場合、価電子帯より高い位置にドープ準位があり、可視光吸収によってそのドープ準位に生成する正孔の酸化力は、酸化チタンと比較して減少する。）
しかしながら、上記半導体化合物は、可視光触媒活性があまり強力ではなく、たとえば可視光による分解対象となる環境汚染有機物質によっては、これを十分に分解できない場合があり、光触媒活性の向上が課題であった。
For example, semiconductor compounds (metal oxides) such as tungsten oxide, iron oxide, indium oxide, vanadium oxide, and bismuth oxide that can absorb visible light due to a smaller band gap than titanium oxide are visible light active. It is expected as a new photocatalyst (visible light responsive photocatalyst). In these semiconductor compounds, the atomic orbital of oxygen contributes greatly to the valence band, and the position of the valence band hardly changes even if the metals are different. The band gap is small because the lower end of the conduction band is lowered. In this case, even if the band gap is small and visible light responsiveness, the holes generated in the valence band by electronic excitation do not decrease the oxidizing power for the adsorbed substrate. (On the other hand, in the case of the above-described nitrogen-doped titanium oxide, there is a doping level at a position higher than the valence band, and the oxidizing power of holes generated in the doping level by absorption of visible light is reduced compared to titanium oxide. To do.)
However, the above-mentioned semiconductor compound is not so strong in visible photocatalytic activity. For example, depending on the environmental pollutant organic substance to be decomposed by visible light, it may not be sufficiently decomposed, and improvement in photocatalytic activity has been a problem. .
すなわち、たとえば、アセトアルデヒドやホルムアルデヒドなどのアルデヒド類、酢酸や蟻酸などのカルボン酸類などの環境汚染有機物質を酸化タングステンなどの可視光応答性の光触媒を用いて可視光照射により分解除去しようとする場合、アルデヒドやカルボン酸の濃度が大きくなると、完全な分解によって最終的に生成する二酸化炭素にまで速やかに分解されるのはその一部分だけで、残りは二酸化炭素にまで速やかに分解されないという問題があった。 That is, for example, when trying to decompose and remove environmental pollutant organic substances such as aldehydes such as acetaldehyde and formaldehyde and carboxylic acids such as acetic acid and formic acid by visible light irradiation using a visible light responsive photocatalyst such as tungsten oxide, When the concentration of aldehyde or carboxylic acid increases, there is a problem that only a portion of the aldehyde or carboxylic acid is rapidly decomposed to carbon dioxide, which is finally produced by complete decomposition, and the rest is not rapidly decomposed to carbon dioxide. .
具体的に言えば、高濃度（2500ppm以上）のアセトアルデヒドを酸化タングステン光触媒により光分解しようとすると、光分解反応による二酸化炭素の生成が途中から著しく遅くなり、アセトアルデヒドを完全に分解した場合に発生する量には速やかには到達せず、またアセトアルデヒドは速やかには完全消失せず長時間にわたって残留し続けるといった難点があった。 Specifically, when high-concentration (2500 ppm or more) acetaldehyde is photodegraded with a tungsten oxide photocatalyst, carbon dioxide generation by the photodegradation reaction is remarkably slowed in the middle, which occurs when acetaldehyde is completely decomposed. The amount was not reached quickly, and acetaldehyde did not completely disappear quickly and remained for a long time.
このため、従来の可視光応答性光触媒の光分解作用を補填し、かつ用いる光触媒の種類の如何を問わず、その光触媒活性を促進できる触媒活性促進剤の開発が強く求められているが、未だそのような活性促進剤が得られていないのが現状である。
本発明は、可視光応答性光触媒の光分解作用を補填し、かつ用いる当該光触媒の種類の如何を問わず、その光触媒活性を促進できる触媒活性促進剤および該触媒活性促進剤を併用した可視光応答性光触媒、更には、該可視光応答性触媒を用いた環境汚染有機物質の効率的な光分解法を提供することを課題としている。 The present invention compensates for the photodegradation action of a visible light responsive photocatalyst and, regardless of the type of the photocatalyst used, a catalytic activity promoter capable of promoting the photocatalytic activity, and visible light using the catalytic activity promoter in combination. It is an object of the present invention to provide a responsive photocatalyst and an efficient photodecomposition method for environmental pollutant organic substances using the visible light responsive catalyst.
本発明者らは、上記課題を解決するために鋭意検討した結果、銅化合物が共存する可視光応答性光触媒の存在下では、可視光照射下でも高濃度の環境汚染有機物質、たとえばアルデヒドやカルボン酸がほとんど二酸化炭素まで速やかに分解し、長時間にわたり残留することがないことを知見し、本発明を完成するに至った。 As a result of intensive studies to solve the above problems, the present inventors have found that in the presence of a visible light responsive photocatalyst coexisting with a copper compound, a high concentration of environmental pollutant organic substances such as aldehydes and carboxylic acids even under visible light irradiation. It was found that the acid decomposes rapidly to almost carbon dioxide and does not remain for a long time, and the present invention has been completed.
すなわち、この出願は、以下の発明を提供するものである。
（１）銅化合物を含有してなることを特徴とする可視光応答性光触媒の触媒活性促進剤。
（２）銅化合物が、酸化銅、硝酸銅及び硫酸銅から選ばれた少なくとも一種の化合物であることを特徴とする上記（１）の触媒活性促進剤。
（３）可視光応答性光触媒がタングステン化合物であることを特徴とする上記（１）又は（２）の触媒活性促進剤。
（４）タングステン化合物が酸化タングステンであることを特徴とする上記（３）の触媒活性促進剤。
（５）上記（１）から（４）のうちのいずれかの触媒活性促進剤を併用してなることを特徴とする可視光応答性光触媒。
（６）触媒活性促進剤が可視光応答性光触媒に混合ないしは担持されていることを特徴とする上記（５）の可視光応答性光触媒。
（７）触媒活性促進剤と可視光応答性触媒とがそれぞれ離間されていること特徴とする上記（５）の可視光応答性光触媒。
（８）粉末状又は薄膜状であることを特徴とする上記（５）から（７）のうちのいずれかの可視光応答性光触媒。
（９）上記（５）から（８）のうちのいずれかの可視光応答性光触媒を使用することを特徴とする環境汚染有機物質の光分解法。
（１０）環境汚染有機物質がアルデヒド類又はカルボン酸類であることを特徴とする上記（９）の光分解法。
That is, this application provides the following invention.
(1) A catalyst activity promoter for a visible light responsive photocatalyst comprising a copper compound.
(2) The catalyst activity promoter according to (1), wherein the copper compound is at least one compound selected from copper oxide, copper nitrate, and copper sulfate.
(3) The catalyst activity promoter according to (1) or (2) above, wherein the visible light responsive photocatalyst is a tungsten compound.
(4) The catalyst activity promoter according to (3) above, wherein the tungsten compound is tungsten oxide.
(5) A visible light responsive photocatalyst comprising the catalyst activity promoter according to any one of (1) to (4) above.
(6) The visible light responsive photocatalyst according to (5) above, wherein the catalyst activity promoter is mixed or supported on the visible light responsive photocatalyst.
(7) The visible light responsive photocatalyst according to (5) above, wherein the catalyst activity promoter and the visible light responsive catalyst are separated from each other.
(8) The visible light responsive photocatalyst according to any one of (5) to (7) above, wherein the visible light responsive photocatalyst is in the form of a powder or a thin film.
(9) A method for photodegrading an environmental pollutant organic substance, wherein the visible light responsive photocatalyst according to any one of (5) to (8) is used.
(10) The photolysis method according to (9) above, wherein the environmental pollutant organic substance is an aldehyde or a carboxylic acid.
本発明の触媒活性促進剤は、可視光応答性光触媒の光分解作用を補填し、かつ用いる当該光触媒の種類の如何を問わず、その光触媒活性を促進することができる。したがって、当該触媒活性促進剤を併用した可視光応答性光触媒を用いると高濃度の環境汚染有機物質、たとえば2500ppm以上のアルデヒド類やカルボン酸類を可視光照射下でもほとんど二酸化炭素にまで速やかに分解して除去することが可能となる。また、本発明に係る可視光応答性光触媒は可視光によって機能するため、太陽光を有効に利用したり、紫外光が極めて弱い室内において使用したりすることが期待できる。 The catalyst activity promoter of the present invention can compensate for the photodegradation action of the visible light responsive photocatalyst and can promote the photocatalytic activity regardless of the type of the photocatalyst used. Therefore, when a visible light responsive photocatalyst combined with the catalytic activity promoter is used, high-concentration organic pollutants such as aldehydes and carboxylic acids of 2500 ppm or more are rapidly decomposed to almost carbon dioxide even under visible light irradiation. Can be removed. In addition, since the visible light responsive photocatalyst according to the present invention functions by visible light, it can be expected to use sunlight effectively or use it in a room where ultraviolet light is extremely weak.
本発明の触媒活性促進剤は、銅化合物を含有することを特徴としている。 The catalyst activity promoter of the present invention is characterized by containing a copper compound.
このような銅化合物は可視光応答性光触媒の光分解作用を補填し、かつ用いる当該光触媒の種類の如何を問わず、その光触媒活性を促進することができる。ここで、本発明における「可視光応答性光触媒」とは、酸化チタンに比較して価電子帯の位置は変わらず伝導帯の位置が低くなることでバンドギャップが小さくなって可視光応答性になった半導体化合物（金属酸化物）、をいう。したがって、上述したように、価電子帯より高い位置にドープ準位があり、可視光吸収によってそのドープ準位に生成する正孔の酸化力が酸化チタンと比較して減少する、窒素ドープ酸化チタンは本発明における「可視光応答性光触媒」に含まれない。 Such a copper compound compensates for the photodegradation action of the visible light responsive photocatalyst and can promote the photocatalytic activity regardless of the type of the photocatalyst used. Here, the “visible light responsive photocatalyst” in the present invention means that the position of the valence band is not changed and the position of the conduction band is lower than that of titanium oxide, so that the band gap is reduced and the visible light response is improved. A semiconductor compound (metal oxide). Therefore, as described above, nitrogen-doped titanium oxide has a doped level at a position higher than the valence band, and the oxidizing power of holes generated in the doped level by visible light absorption is reduced as compared with titanium oxide. Is not included in the “visible light-responsive photocatalyst” in the present invention.
この触媒活性促進剤を可視光応答性光触媒と併用すると可視光照射によって、たとえば高濃度（2500ppm以上）のアルデヒド類やカルボン酸類がほとんど完全に二酸化炭素にまで速やかに分解され、長時間にわたり残留することもない。銅以外の金属の化合物が共存しても同様の効果は見られないのに対して、様々な銅化合物でこの効果が得られる。 When this catalytic activity promoter is used in combination with a visible light responsive photocatalyst, for example, high concentrations (2500 ppm or more) of aldehydes and carboxylic acids are almost completely decomposed rapidly into carbon dioxide by irradiation with visible light, and remain for a long time. There is nothing. Even if a metal compound other than copper coexists, the same effect is not seen, whereas this effect is obtained with various copper compounds.
銅化合物としては、銅を含む化合物であれば特に制限はないが、酸化銅や硝酸銅、硫酸銅、塩化銅などの銅化合物塩を用いることが好ましい。特に、CuO、Cu2O、Cu(NO3)2・3H2O、CuSO4・5H2O、CuCl2などが好ましく、そのうちCuOが特に好ましく使用される。 The copper compound is not particularly limited as long as it is a compound containing copper, but it is preferable to use a copper compound salt such as copper oxide, copper nitrate, copper sulfate, or copper chloride. In particular, CuO, Cu 2 O, Cu (NO 3 ) 2 .3H 2 O, CuSO 4 .5H 2 O, CuCl 2 and the like are preferable, and CuO is particularly preferably used.
これらの銅化合物は、一般的には、併用する可視光応答性光触媒に対して０．０１重量％〜５０重量％の範囲内において使用することが考慮される。この使用量については銅化合物と可視光応答性光触媒の種類、そして両者の併用の態様によって具体的に定めることができる。 It is considered that these copper compounds are generally used in the range of 0.01% by weight to 50% by weight with respect to the visible light responsive photocatalyst used in combination. About this usage-amount, it can determine concretely with the kind of copper compound and visible light responsive photocatalyst, and the aspect of combined use of both.
本発明に係る可視光応答性光触媒の触媒活性促進剤が、当該光触媒の機能を補填し、かつ用いる光触媒の種類に拘わらず、環境汚染有機物質の分解作用を促進する理由の詳細は現時点では明らかではないが、以下のように推定している。 Details of the reason why the catalyst activity promoter of the visible light responsive photocatalyst according to the present invention supplements the function of the photocatalyst and promotes the decomposition action of environmental pollutant organic substances regardless of the type of the photocatalyst used are clear at present. However, it is estimated as follows.
たとえば、可視光応答性光触媒を用いて高濃度（2500ppm以上）で存在するアルデヒド類を光分解する場合には、光触媒活性が強力でないと分解されにくい中間体が生成し、分解反応が進行しにくくなる。この場合、銅化合物が存在すると、この中間体の分解反応が促進される。銅化合物が単に可視光応答性光触媒の近傍に存在するだけで光分解反応が促進されるのはこのことによると考えられる。したがって、光触媒活性があまり強力でない可視光応答性光触媒を用いたとしても、これに銅化合物を共存併用させることにより、分解し難い中間体の分解が促進され、アルデヒド類がほとんど完全に二酸化炭素にまで速やかに分解される。 For example, when photodegrading aldehydes present at a high concentration (2500 ppm or more) using a visible light-responsive photocatalyst, an intermediate that is difficult to decompose is generated unless the photocatalytic activity is strong, and the decomposition reaction is unlikely to proceed. Become. In this case, if a copper compound is present, the decomposition reaction of this intermediate is promoted. It is considered that this is because the photodecomposition reaction is promoted only by the presence of the copper compound in the vicinity of the visible light responsive photocatalyst. Therefore, even when using a visible light responsive photocatalyst that does not have a strong photocatalytic activity, the coexistence of a copper compound promotes the decomposition of an intermediate that is difficult to decompose, and aldehydes are almost completely converted to carbon dioxide. It is quickly disassembled.
またカルボン酸類はもともと分解されにくく、光触媒活性があまり強力でない可視光応答性光触媒を用いて光分解しても分解速度は小さい。この場合、銅化合物が存在すると、もとのカルボン酸もしくはその分解途中で生成した中間体が銅化合物により可視光応答性光触媒によって分解されやすくなるために光分解が促進され分解速度も大きくなる。したがって、光触媒活性があまり強力でない可視光応答性光触媒を用いたとしても、これに銅化合物を共存併用させることにより、カルボン酸類がほとんど完全に二酸化炭素にまで速やかに分解される。 Carboxylic acids are hardly decomposed from the beginning, and the degradation rate is low even when photodegradation is performed using a visible light-responsive photocatalyst that is not very strong in photocatalytic activity. In this case, if the copper compound is present, the original carboxylic acid or an intermediate formed during the decomposition thereof is easily decomposed by the copper compound by the visible light responsive photocatalyst, so that photolysis is promoted and the decomposition rate is increased. Therefore, even if a visible light responsive photocatalyst having a less strong photocatalytic activity is used, the carboxylic acids are almost completely decomposed quickly to carbon dioxide by coexisting with the copper compound.
このように、可視光応答性光触媒を用いた環境汚染有機物質の光分解反応において、可視光応答性光触媒の光触媒活性があまり強力でない場合であっても、銅化合物はもとの環境汚染有機物質もしくは途中で生成する分解しにくい中間体を光触媒反応により分解されやすくさせることで反応を促進する。 As described above, in the photodecomposition reaction of the environmental pollutant organic substance using the visible light responsive photocatalyst, even if the photocatalytic activity of the visible light responsive photocatalyst is not so strong, the copper compound is the original environmental pollutant organic substance. Alternatively, the reaction is promoted by making the intermediate that is generated in the middle of being difficult to decompose easily decomposed by the photocatalytic reaction.
以上の理由から、本発明の触媒活性促進剤と併用できる可視光応答性光触媒としては、伝導帯の位置が低くなることによりバンドギャップが酸化チタンと比較して小さくて可視光を吸収できるものであれば、その光触媒活性の大小に拘わらず、従来公知の可視光応答性の半導体化合物（金属酸化物）の何れも使用できる。 For the above reasons, the visible light responsive photocatalyst that can be used in combination with the catalyst activity promoter of the present invention is capable of absorbing visible light with a lower band gap than titanium oxide due to the lower position of the conduction band. As long as the photocatalytic activity is large, any conventionally known visible light responsive semiconductor compound (metal oxide) can be used.
このような半導体化合物としては、酸化タングステン、酸化鉄、酸化インジウム、酸化バナジウム、酸化ビスマス、鉄―タングステン酸化物などが例示される。その中でも、酸化タングステンが特に好ましい。 Examples of such semiconductor compounds include tungsten oxide, iron oxide, indium oxide, vanadium oxide, bismuth oxide, and iron-tungsten oxide. Among these, tungsten oxide is particularly preferable.
本発明に係る上記銅化合物を併用した可視光応答性光触媒は、いくつかの態様を採ることができる。 The visible light responsive photocatalyst using the copper compound according to the present invention can take several modes.
その一つは銅化合物と可視光応答性光触媒を混合したものである。この場合、典型的には、それぞれの粉末を適宜の量をとり乳鉢を用いてよく粉砕・混合し、そのままの粉末状もしくは薄膜形状などに成形して光触媒として用いる。この態様のものは単に混合するだけなので様々な種類の銅化合物と可視光応答性光触媒を共存させることができる。 One of them is a mixture of a copper compound and a visible light responsive photocatalyst. In this case, typically, an appropriate amount of each powder is taken and pulverized and mixed well using a mortar, and is formed into a powder or thin film as it is and used as a photocatalyst. Since the thing of this aspect is only mixed, various types of copper compounds and visible light responsive photocatalysts can coexist.
以下に酸化タングステン粉末にCuO粉末を混合する場合を例として説明する。 Hereinafter, a case where CuO powder is mixed with tungsten oxide powder will be described as an example.
例えば、酸化タングステン粉末とCuO粉末を混合したものに高濃度のアセトアルデヒド存在下で420nmより長波長の可視光を照射するとアセトアルデヒドをほとんどすべて二酸化炭素にまで完全に分解できる。銅化合物の添加量、照射光の強度・照射時間などの最適条件は添加する銅化合物や可視光応答性光触媒の種類、形状などを考慮し適宜設定するが、酸化タングステン粉末に、市販されている比較的粒子径が大きいCuO粉末を混合する場合では、CuO粉末は酸化タングステン粉末に対して１重量％〜５重量％が好ましく、より好ましくは１重量％〜２重量％である。 For example, when a mixture of tungsten oxide powder and CuO powder is irradiated with visible light having a wavelength longer than 420 nm in the presence of a high concentration of acetaldehyde, almost all acetaldehyde can be completely decomposed into carbon dioxide. Optimum conditions such as the amount of copper compound added, the intensity of irradiation light, and the irradiation time are set as appropriate in consideration of the type and shape of the added copper compound and visible light responsive photocatalyst, but are commercially available for tungsten oxide powders. In the case of mixing a CuO powder having a relatively large particle size, the CuO powder is preferably 1% by weight to 5% by weight, more preferably 1% by weight to 2% by weight with respect to the tungsten oxide powder.
また、銅化合物と可視光応答性光触媒を併用する別の態様としては、可視光応答性光触媒に銅化合物を担持させたものを挙げることができる。この場合、担持方法により担持される銅化合物は異なるが、とくにCuOとして担持させることが好ましい。例えば、可視光応答性光触媒の粉末に硫酸銅や硝酸銅の水溶液やエタノール溶液などを加えて混合し７０℃〜８０℃で乾燥させてから５００℃〜５５０℃で焼成するとCuOを担持することができる。 Moreover, as another aspect which uses a copper compound and a visible light responsive photocatalyst together, what carried the copper compound on the visible light responsive photocatalyst can be mentioned. In this case, the copper compound supported by the supporting method is different, but it is particularly preferable to support it as CuO. For example, an aqueous solution of copper sulfate or copper nitrate or an ethanol solution is added to a visible light responsive photocatalyst powder, mixed, dried at 70 ° C. to 80 ° C., and then baked at 500 ° C. to 550 ° C. to carry CuO. it can.
銅化合物を担持させる最適な条件は、担持する銅化合物や可視光応答性光触媒の種類、形状などを考慮し適宜設定される。 The optimum conditions for supporting the copper compound are appropriately set in consideration of the type and shape of the supported copper compound and visible light responsive photocatalyst.
例えば、添加するCuO粉末の粒子径が小さくて表面積が大きい場合は最適な添加量も小さくなる傾向がある。それで、市販のCuO粉末は粒子径が大きくて比較的表面積が小さいのに対して、湿式低温合成したCuO粉末や低温での含浸担持法などで担持したCuOは超微粒子となっていて表面積が大きいので、必要とされる添加量も少なくできる。 For example, when the particle diameter of the CuO powder to be added is small and the surface area is large, the optimum addition amount tends to be small. Therefore, while the commercially available CuO powder has a large particle size and a relatively small surface area, CuO powder synthesized by wet low temperature and the CuO supported by impregnation support method at low temperature are ultrafine particles and have a large surface area. Therefore, the required addition amount can be reduced.
この態様の可視光応答性光触媒は、担持により銅化合物を添加することから、銅化合物が可視光応答性光触媒のすぐ近くに存在するため大きな触媒活性促進効果が期待できることや銅化合物が均一に分散されて光触媒の光吸収を妨げにくいことなどの利点がある。 Since the visible light responsive photocatalyst of this embodiment is added with a copper compound by loading, the copper compound is present in the immediate vicinity of the visible light responsive photocatalyst, so that a large catalytic activity promoting effect can be expected and the copper compound is uniformly dispersed. Thus, there is an advantage that it is difficult to prevent light absorption of the photocatalyst.
本発明による可視光応答性光触媒は上記したような銅化合物と可視光応答性光触媒を混合や担持した態様に限定されるものではなく、混合や担持することなくそれぞれを別体として存在させることも可能である。 The visible light responsive photocatalyst according to the present invention is not limited to the embodiment in which the copper compound and the visible light responsive photocatalyst are mixed or supported as described above, and may exist separately as a separate body without being mixed or supported. Is possible.
たとえば、銅化合物と可視光応答性光触媒を同一基板の別々の箇所に配置して共存させ一体としてこれを機能させることにより、非混合状態の可視光応答性光触媒を作製することができる。 For example, a non-mixed visible light responsive photocatalyst can be produced by arranging a copper compound and a visible light responsive photocatalyst at different locations on the same substrate and causing them to coexist and function together.
この態様のものは、添加する銅化合物が可視光応答性光触媒の光吸収を妨げないようにするなど使用する状況に適するように形状を設計できるといった利点を有するものである。 The thing of this aspect has an advantage that a shape can be designed so that it may be suitable for a use situation, such as preventing the optical absorption of the visible light responsive photocatalyst from adding the copper compound.
本発明に係る可視光応答性光触媒においては、銅化合物を可視光応答性光触媒と接触させておくことが好ましいが、必ずしもそのような態様のものに限定されず、両者が離間した場合であっても近傍に存在すれば、その光触媒効果が十分に期待できる。 In the visible light responsive photocatalyst according to the present invention, it is preferable to keep the copper compound in contact with the visible light responsive photocatalyst. However, the present invention is not necessarily limited to such a mode, and the two are separated from each other. If it exists in the vicinity, the photocatalytic effect can be sufficiently expected.
また、本発明の可視光応答性光触媒においては、銅化合物と可視光応答性光触媒の両者に可視光を照射することが望ましいが、銅化合物に光が直接照射されなくても所望の光触媒活性を得ることができる。 In the visible light responsive photocatalyst of the present invention, it is desirable to irradiate both the copper compound and the visible light responsive photocatalyst with visible light, but the desired photocatalytic activity can be obtained even if the copper compound is not directly irradiated with light. Obtainable.
本発明による可視光応答性光触媒は粉末形状に限定されるものではなく、薄膜などに形成して使用することもできる。例えば、上記した可視光応答性光触媒粉末と銅化合物粉末の混合体を薄膜形状に形成して使用することができる。また銅化合物と可視光応答性光触媒をそれぞれ別途に薄膜に形成し共存させたり、可視光応答性光触媒薄膜上に銅化合物の薄膜を積層させたりして使用することもできる。薄膜の作製は通常に用いられているドクターブレード法やスピンコート法などによって行う。これらの薄膜の形状は可視光応答性光触媒ができるだけ銅化合物に妨げられることなく光を吸収できるように最適化する。 The visible light responsive photocatalyst according to the present invention is not limited to a powder form, and can be used by being formed into a thin film or the like. For example, the above-mentioned mixture of visible light responsive photocatalyst powder and copper compound powder can be used in the form of a thin film. In addition, the copper compound and the visible light responsive photocatalyst can be separately formed on a thin film and coexist, or a copper compound thin film can be laminated on the visible light responsive photocatalyst thin film. The thin film is produced by a commonly used doctor blade method, spin coating method, or the like. The shape of these thin films is optimized so that the visible light responsive photocatalyst can absorb light as much as possible without being obstructed by the copper compound.
本発明に係る可視光応答性光触媒は、環境汚染有機物質を光分解するための触媒として極めて有効である。 The visible light responsive photocatalyst according to the present invention is extremely effective as a catalyst for photodegrading environmental pollutant organic substances.
環境汚染有機物質としては、アセトアルデヒドやホルムアルデヒドなどのアルデヒド類、酢酸や蟻酸などカルボン酸類、ベンゼン・トルエンなどの芳香族化合物類、ジクロロメタンなどのハロゲン化アルキル類などが挙げられる。またアルコール類やケトン類、エステル類、炭化水素類等にも有効である。さらに、有機物質だけでなく、COやNOx分解など無機物の無害化にも有効である。 Examples of environmental pollutants include aldehydes such as acetaldehyde and formaldehyde, carboxylic acids such as acetic acid and formic acid, aromatic compounds such as benzene and toluene, and alkyl halides such as dichloromethane. It is also effective for alcohols, ketones, esters, hydrocarbons and the like. Furthermore, it is effective for detoxifying not only organic substances but also inorganic substances such as CO and NOx decomposition.
本発明に係る可視光応答性光触媒は、この中でもカルボン酸類やアルデヒド類に対して特に有効である。 The visible light responsive photocatalyst according to the present invention is particularly effective for carboxylic acids and aldehydes among them.
また環境汚染有機物質は気相に存在するものだけではなく、水などの液体に溶解しているものも本発明の可視光応答性光触媒を用いて分解することができる。液相において本発明の可視光応答性光触媒を用いると添加した銅化合物がイオンとして溶解する場合もあるが、そのような場合でも光触媒活性は促進される。 Moreover, not only those which are present in the gas phase but also those which are dissolved in a liquid such as water can be decomposed using the visible light responsive photocatalyst of the present invention. When the visible light responsive photocatalyst of the present invention is used in the liquid phase, the added copper compound may be dissolved as ions, but even in such a case, the photocatalytic activity is promoted.
以下、本発明を実施例によりさらに具体的に説明するが、本発明はこの実施例によって何ら限定されるものではない。
＜実施例１、比較例１＞
酸化タングステン粉末（高純度化学、９９．９９％）にCuO粉末（和光純薬工業、９９．９％）を１重量％、２重量％および５重量％の各々を加えて乳鉢を用いてよく粉砕・混合し、本発明の可視光応答性光触媒粉末を作製した。
Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the examples.
<Example 1, comparative example 1>
Add 1% by weight, 2% by weight and 5% by weight of CuO powder (Wako Pure Chemical Industries, 99.9%) to tungsten oxide powder (high purity chemical, 99.99%) and pulverize them well using a mortar. -Mixed to produce a visible light responsive photocatalyst powder of the present invention.
この光触媒を4mlのバイアルびんにおよそ150mg入れ、これにアセトアルデヒドの気体を約40μl（10000ppm）加えて300WのＸｅランプを420nmより短波長をフィルターによりカットした可視光条件で照射し、ガスクロマトグラフィーにより光分解で生じる二酸化炭素の量の時間変化をモニターした。また比較例１として酸化タングステン粉末のみを用いて同様の実験を行った。図１に結果を示す。
なお、本例では、存在するアセトアルデヒドが完全に二酸化炭素にまで分解するとおよそ20000ppmの二酸化炭素が理論的に発生する。
Approximately 150 mg of this photocatalyst is placed in a 4 ml vial, about 40 μl (10000 ppm) of acetaldehyde gas is added, and a 300 W Xe lamp is irradiated under visible light conditions with a wavelength shorter than 420 nm cut by a filter. The change over time in the amount of carbon dioxide produced by photolysis was monitored. As Comparative Example 1, the same experiment was performed using only tungsten oxide powder. The results are shown in FIG.
In this example, when the existing acetaldehyde completely decomposes into carbon dioxide, approximately 20000 ppm of carbon dioxide is theoretically generated.
図１に示すように、比較例１では９０分照射後、9000ppm程度の二酸化炭素が発生するものの、その後２７０分照射しても、二酸化炭素の発生量はほとんど増加しなくなった。 As shown in FIG. 1, in Comparative Example 1, about 9000 ppm of carbon dioxide was generated after 90 minutes of irradiation, but the amount of generated carbon dioxide hardly increased even after irradiation of 270 minutes.
これに対して、CuO粉末を混合したものでは初期の二酸化炭素の発生量は少なくなるものの、２７０分経過後の二酸化炭素発生量は、比較例１のおよそ１．６〜１．９倍となった。
＜実施例２、比較例２＞
酸化タングステン粉末（高純度化学、９９．９９％）にCuO粉末（和光純薬工業、９９．９％）、Cu2O粉末（和光純薬工業、９９．５％）、Cu(NO3)2・3H2O粉末（和光純薬工業、９９．９％）、CuSO4・5H2O粉末（和光純薬工業、特級）をそれぞれ２重量％ずつ加えて乳鉢を用いてよく粉砕・混合し、本発明の可視光応答性光触媒を４種類作製した。
On the other hand, in the case of mixing CuO powder, the initial carbon dioxide generation amount is small, but the carbon dioxide generation amount after 270 minutes has passed is approximately 1.6 to 1.9 times that of Comparative Example 1. It was.
<Example 2, comparative example 2>
Tungsten oxide powder (high purity chemistry, 99.99%), CuO powder (Wako Pure Chemical Industries, 99.9%), Cu 2 O powder (Wako Pure Chemical Industries, 99.5%), Cu (NO 3 ) 2・ 3H 2 O powder (Wako Pure Chemical Industries, 99.9%), CuSO 4・ 5H 2 O powder (Wako Pure Chemical Industries, special grade) were added 2% each by weight and pulverized and mixed well using a mortar. Four types of visible light responsive photocatalysts of the present invention were prepared.
これらの光触媒を4mlのバイアルびんにそれぞれおよそ150mg入れ、これにアセトアルデヒドの気体を約40μl（10000ppm）加えて300WのＸｅランプを１８時間にわたってＡＭ１．５フィルターによる疑似太陽光条件で照射し、ガスクロマトグラフィーにより最終的な二酸化炭素生成量を調べた。また、比較例２として酸化タングステン粉末のみを用いて同様の実験を行った。表１に結果を示す。 Approximately 150 mg of each of these photocatalysts was placed in a 4 ml vial, about 40 μl (10000 ppm) of acetaldehyde gas was added thereto, and a 300 W Xe lamp was irradiated for 18 hours under simulated sunlight conditions using an AM1.5 filter. The final carbon dioxide production was examined by graphy. Further, as Comparative Example 2, a similar experiment was performed using only tungsten oxide powder. Table 1 shows the results.
なお、本例の場合も、アセトアルデヒドが完全に二酸化炭素にまで分解すると理論的におよそ20000ppmの二酸化炭素が発生する。 In the case of this example, when acetaldehyde is completely decomposed into carbon dioxide, approximately 20000 ppm of carbon dioxide is theoretically generated.
表１に示すように、比較例２ではおよそ14840ppmの二酸化炭素しか発生しなかったが、CuOの添加では21032ppm、Cu2Oの添加では20148ppm、CuSO4・5H2Oの添加では22108ppmの二酸化炭素が発生しておりアセトアルデヒドは完全に二酸化炭素に分解した。またCu(NO3)2・3H2Oの添加では16919ppmの二酸化炭素が発生しており比較例２よりも分解反応が進んでいた。 As shown in Table 1, only about 14840 ppm of carbon dioxide was generated in Comparative Example 2, but 21032 ppm with addition of CuO, 20148 ppm with addition of Cu 2 O, and 22108 ppm of carbon dioxide with addition of CuSO 4 .5H 2 O. The acetaldehyde was completely decomposed into carbon dioxide. Moreover, the addition of Cu (NO 3 ) 2 .3H 2 O generated 16919 ppm of carbon dioxide, and the decomposition reaction proceeded more than Comparative Example 2.
以下の方法によって酸化タングステンにCuOを担持させた、本発明の可視光応答性光触媒を作製した。
The visible light responsive photocatalyst of the present invention in which CuO was supported on tungsten oxide was produced by the following method.
酸化タングステン粉末（高純度化学、９９．９９％）1.003gに対して0.5M 硫酸銅水溶液を513μl（CuOとして2重量％に相当）加えてホットプレート上でかき混ぜながら蒸発乾固させ、さらにエタノールで再分散させ、再びホットプレート上でかき混ぜながら蒸発乾固させた後、電気炉内で加熱した。加熱は空気雰囲気において500℃で２時間行った。 Add 513 μl of 0.5M aqueous copper sulfate solution (corresponding to 2% by weight as CuO) to 1.003 g of tungsten oxide powder (high purity chemistry, 99.99%) and stir on a hot plate to evaporate to dryness. It was redispersed and evaporated to dryness while stirring again on a hot plate, and then heated in an electric furnace. Heating was performed at 500 ° C. for 2 hours in an air atmosphere.
この光触媒を4mlのバイアルびんにおよそ150mg入れ、これにアセトアルデヒドの気体を約40μl（10000ppm）加えて300WのＸｅランプを１８時間にわたってＡＭ１．５フィルターによる疑似太陽光条件で照射し、ガスクロマトグラフィーにより最終的な二酸化炭素生成量を調べた。比較例３として酸化タングステン粉末のみを用いて同様の実験を行った。 Approximately 150 mg of this photocatalyst is placed in a 4 ml vial, about 40 μl (10000 ppm) of acetaldehyde gas is added, and a 300 W Xe lamp is irradiated for 18 hours under simulated sunlight conditions using an AM1.5 filter. The final carbon dioxide production was examined. As Comparative Example 3, a similar experiment was performed using only tungsten oxide powder.
なお、本例の場合もアセトアルデヒドが完全に二酸化炭素にまで分解するとおよそ20000ppmの二酸化炭素が発生する。 In the case of this example, approximately 20000 ppm of carbon dioxide is generated when acetaldehyde is completely decomposed into carbon dioxide.
実験の結果、比較例３では12356ppmの二酸化炭素しか発生しなかったが、CuOを担持させたものでは18270ppmの二酸化炭素が発生しており、アセトアルデヒドはほぼ完全に二酸化炭素に分解した。 As a result of the experiment, in Comparative Example 3, only 12356 ppm of carbon dioxide was generated, but in the case of supporting CuO, 18270 ppm of carbon dioxide was generated, and acetaldehyde was almost completely decomposed into carbon dioxide.
またこのような含浸法により酸化タングステンにCuOを担持する場合についてCuO担持量の影響を調べたところ、担持量を0.1重量％付近まで減少させてもアセトアルデヒドはほぼ完全に二酸化炭素に分解し、かつその付近が二酸化炭素発生速度の最大となる最適な担持量であった。この結果は、本発明の可視光応答性光触媒はその調製条件が異なると最適な添加量も異なることを示している。
＜実施例４、比較例４＞
酸化タングステン粉末（高純度化学、９９．９９％）にCuO粉末（和光純薬工業、９９．９％）を２重量％加えて乳鉢を用いてよく粉砕・混合して本発明の可視光応答性光触媒粉末を作製した。
In addition, when the effect of CuO loading was investigated when CuO was supported on tungsten oxide by such impregnation method, acetaldehyde was almost completely decomposed into carbon dioxide even if the loading was reduced to near 0.1% by weight, and The vicinity was the optimum loading amount that maximized the carbon dioxide generation rate. This result shows that the optimum addition amount of the visible light responsive photocatalyst of the present invention varies depending on the preparation conditions.
<Example 4, comparative example 4>
Visible light response of the present invention by adding 2% by weight of CuO powder (Wako Pure Chemical Industries, 99.9%) to tungsten oxide powder (high purity chemistry, 99.99%) and pulverizing and mixing them well using a mortar. A photocatalyst powder was prepared.
この光触媒を4mlのバイアルびんにおよそ150mg入れ、これに液体の酢酸を約10μl加えて300WのＸｅランプをＡＭ１．５フィルターによる疑似太陽光条件で照射し、ガスクロマトグラフィーにより光分解で生じる二酸化炭素の量の時間変化をモニターした。また比較例４として酸化タングステン粉末のみを用いて同様の実験を行った。図２に結果を示す。 About 150 mg of this photocatalyst is placed in a 4 ml vial, about 10 μl of liquid acetic acid is added, and a 300 W Xe lamp is irradiated under simulated sunlight conditions with an AM1.5 filter, and carbon dioxide generated by photolysis by gas chromatography. The amount of time was monitored over time. As Comparative Example 4, a similar experiment was performed using only tungsten oxide powder. The results are shown in FIG.
図２に示すように、比較例４では二酸化炭素は発生するものの発生速度は小さく、１８０分照射しても、8000ppm程度の二酸化炭素しか発生しなかった。 As shown in FIG. 2, in Comparative Example 4, although carbon dioxide was generated, the generation rate was low, and even when irradiated for 180 minutes, only about 8000 ppm of carbon dioxide was generated.
これに対して、CuO粉末を混合したものでは二酸化炭素の発生速度は著しく大きくなり、１８０分経過後の二酸化炭素発生量はおよそ37000ppmで、比較例４のおよそ４．６倍となった。
＜実施例５、比較例５＞
酸化タングステン粉末（関東化学、＞９９％）にCuO粉末（和光純薬工業、９９．９％）を２重量％加えて乳鉢を用いてよく粉砕・混合して本発明の可視光応答性光触媒粉末を作製した。
In contrast, when the CuO powder was mixed, the carbon dioxide generation rate was remarkably increased, and the carbon dioxide generation amount after 180 minutes was about 37000 ppm, which was about 4.6 times that of Comparative Example 4.
<Example 5, Comparative Example 5>
Visible light-responsive photocatalyst powder of the present invention by adding 2% by weight of CuO powder (Wako Pure Chemical Industries, 99.9%) to tungsten oxide powder (Kanto Chemical Co.,> 99%) and pulverizing and mixing them well using a mortar. Was made.
この光触媒を4.4mlのバイアルびんにおよそ150mg入れ、これに様々な種類の液体の有機物を約2μl（アセトアルデヒドでは気相で9000ppm分に相当）加えて300WのＸｅランプを３時間にわたってそのまま全光照射し、ガスクロマトグラフィーにより最終的な二酸化炭素生成量を調べた。またそれぞれについて比較例５として酸化タングステン粉末のみを用いて同様の実験を行った。図３に結果を示す。 About 150 mg of this photocatalyst is put in a 4.4 ml vial, and about 2 μl of various kinds of liquid organic substances (corresponding to 9000 ppm in the gas phase in acetaldehyde) is added to this, and a 300 W Xe lamp is irradiated for 3 hours as it is. The final carbon dioxide production was examined by gas chromatography. Moreover, the same experiment was conducted using only tungsten oxide powder as Comparative Example 5 for each. The results are shown in FIG.
どの有機物についても、酸化タングステンを単独で用いた比較例５よりもCuO粉末を混合したものの方が多量の二酸化炭素が発生した。この結果は、酸化タングステンにCuOを添加した本発明の可視光応答性光触媒は多くの有機物の分解に対して有効であることを示している。
＜実施例６、比較例６＞
酸化タングステン粉末（和光純薬工業、＞９９％）を4.4mlのバイアルびんにおよそ150mg入れ、それにCuの量が１μmolとなるように銅化合物塩（CuSO4またはCuCl2）と水40μlを添加した。このとき銅化合物塩の一部は水に溶解している。さらにこれに分解する有機物として液体のギ酸を約2μl加えて300WのＸｅランプを420nmより短波長をフィルターによりカットした可視光条件で照射し、ガスクロマトグラフィーにより光分解で生じる二酸化炭素の量の時間変化をモニターした。また比較例６として銅化合物塩を添加せずに同様の実験を行った。図４に結果を示す。
For any organic matter, a larger amount of carbon dioxide was generated when the CuO powder was mixed than with Comparative Example 5 where tungsten oxide was used alone. This result shows that the visible light-responsive photocatalyst of the present invention in which CuO is added to tungsten oxide is effective for the decomposition of many organic substances.
<Example 6, comparative example 6>
Approximately 150 mg of tungsten oxide powder (Wako Pure Chemical Industries,> 99%) was put in a 4.4 ml vial, and copper compound salt (CuSO 4 or CuCl 2 ) and 40 μl of water were added so that the amount of Cu was 1 μmol. . At this time, a part of the copper compound salt is dissolved in water. Furthermore, about 2 μl of liquid formic acid is added as an organic substance to be decomposed, and a 300 W Xe lamp is irradiated under visible light conditions with a wavelength shorter than 420 nm cut by a filter, and the amount of carbon dioxide generated by photolysis by gas chromatography. Changes were monitored. Further, as Comparative Example 6, the same experiment was performed without adding a copper compound salt. The results are shown in FIG.
図４に示したように、銅化合物塩を添加しない比較例６では二酸化炭素の発生速度は著しく小さく、１８０分間照射しても、わずかの二酸化炭素しか発生しなかった。 As shown in FIG. 4, in Comparative Example 6 in which no copper compound salt was added, the generation rate of carbon dioxide was remarkably small, and only a small amount of carbon dioxide was generated even after irradiation for 180 minutes.
これに対して、銅化合物塩を添加したものでは二酸化炭素の発生速度が著しく大きくなり、１８０分経過後の二酸化炭素発生量では、比較例６に対して、CuSO4添加でおよそ１５倍、CuCl2添加でおよそ４７倍となった。この結果は、本発明の可視光応答性光触媒を液相中で用いることにより、銅化合物がイオンとして溶解する場合でも、水などの液体に溶解している環境汚染有機物質であっても分解できることを示している。 On the other hand, when the copper compound salt is added, the carbon dioxide generation rate is remarkably increased. With respect to the amount of carbon dioxide generated after the lapse of 180 minutes, the addition of CuSO 4 is about 15 times the CuCl 4 addition, and the CuCl. Addition of 2 resulted in a 47-fold increase. This result shows that by using the visible light responsive photocatalyst of the present invention in the liquid phase, even if the copper compound is dissolved as an ion, it can be decomposed even if it is an environmental pollutant organic substance dissolved in a liquid such as water. Is shown.
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