JP2003340288A - Visible light responsive photocatalyst and method for producing the same - Google Patents
Visible light responsive photocatalyst and method for producing the sameInfo
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- JP2003340288A JP2003340288A JP2002158094A JP2002158094A JP2003340288A JP 2003340288 A JP2003340288 A JP 2003340288A JP 2002158094 A JP2002158094 A JP 2002158094A JP 2002158094 A JP2002158094 A JP 2002158094A JP 2003340288 A JP2003340288 A JP 2003340288A
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- visible light
- titanium oxide
- heating
- ammonia gas
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Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は可視光によっても光
触媒活性を有しかつ紫外光活性が改善された、可視光応
答性光触媒およびその製造方法に関する。TECHNICAL FIELD The present invention relates to a visible light responsive photocatalyst having a photocatalytic activity even with visible light and having an improved ultraviolet light activity, and a method for producing the same.
【０００２】[0002]
【従来の技術】近年、酸化チタンは、その酸化分解能、
親水化能などの光触媒作用が注目され、環境浄化、有害
物分解、汚れの分解、抗菌、防汚など様々な用途で応用
されている。しかしながら、これらの光触媒作用は紫外
光の吸収がなければ作用しないため、太陽光の当たらな
い屋内では機能せず、屋内用途には別途紫外線を放射す
る水銀ランプ、紫外線ランプなどの紫外線源を設置しな
ければならなかった。2. Description of the Related Art In recent years, titanium oxide has a
The photocatalytic action such as hydrophilicity has attracted attention and has been applied in various applications such as environmental purification, decomposition of harmful substances, decomposition of dirt, antibacterial and antifouling. However, since these photocatalytic actions do not work without absorption of ultraviolet light, they do not work indoors where the sunlight does not hit, and for indoor use a separate ultraviolet source such as a mercury lamp or ultraviolet lamp that emits ultraviolet rays is installed. I had to.
【０００３】これらの問題点を解決するため、特別な紫
外線源を必要とせず可視光によっても光触媒作用を発揮
する可視光応答性光触媒が提案され始めている。In order to solve these problems, a visible light responsive photocatalyst that does not require a special ultraviolet ray source and exhibits a photocatalytic action even by visible light has been proposed.
【０００４】例えば、特開平１１−３３３３０１号公報
に、市販の酸化チタンを水素及びメタンガスの存在する
雰囲気下プラズマ処理することにより可視光応答性を付
与する方法が提案されている。また、特開２０００−１
４０６３６号公報には、窒素ガス雰囲気下プラズマ処理
することにより可視光応答性を付与する方法が提案され
ている。しかしながらこれらの方法は高価なプラズマ処
理装置を必要とし、また一度に大量の酸化チタンを処理
できないため、工業的に有利ではなかった。For example, Japanese Patent Laid-Open No. 11-333301 proposes a method of imparting visible light responsiveness by subjecting commercially available titanium oxide to plasma treatment in an atmosphere containing hydrogen and methane gas. In addition, JP 2000-1
Japanese Patent No. 40636 proposes a method of imparting visible light responsiveness by performing plasma treatment in a nitrogen gas atmosphere. However, these methods require an expensive plasma processing apparatus and cannot process a large amount of titanium oxide at one time, which is not industrially advantageous.
【０００５】更に、特開２００１−２０７０８２号公報
には、酸化チタンの微粒子をアンモニアの雰囲気下７０
０℃で熱処理することにより可視光応答性を付与する方
法が提案されている。この方法は比較的大量の酸化チタ
ンを一度にまたは連続的に処理することを可能とするも
ので工業的に有利である。しかしながら、この方法によ
り製造された光触媒は可視光応答性は有するものの、酸
化チタンが本来有していた紫外光による光触媒活性が大
きく低下するという問題があった。Further, in Japanese Patent Laid-Open No. 2001-207082, fine particles of titanium oxide are treated under an atmosphere of ammonia.
A method of imparting visible light responsiveness by heat treatment at 0 ° C. has been proposed. This method is industrially advantageous because it allows a relatively large amount of titanium oxide to be treated at once or continuously. However, although the photocatalyst produced by this method has visible light responsiveness, there was a problem that the photocatalytic activity due to ultraviolet light, which titanium oxide originally had, was greatly reduced.
【０００６】[0006]
【発明が解決しようとする課題】本発明は、上記のよう
な従来技術の問題点を解決し、可視光によっても光触媒
活性を有しかつ紫外光活性が改善された可視光応答性光
触媒およびその製造方法を提供するものである。DISCLOSURE OF THE INVENTION The present invention solves the problems of the prior art as described above, and has a visible light responsive photocatalyst having a photocatalytic activity even with visible light and an improved ultraviolet light activity. A manufacturing method is provided.
【０００７】[0007]
【課題を解決するための手段】本発明は、可視光によっ
ても光触媒活性を有しかつ紫外光活性が改善された可視
光応答性光触媒およびその製造方法に関する。この可視
光応答性光触媒は、酸化チタンをアンモニアガスまたは
加熱によりアンモニアを放出する物質と接触させながら
加熱することにより酸化チタンに可視光応答性を付与
し、次いでこれを酸化雰囲気で加熱することにより製造
することができる。The present invention relates to a visible light responsive photocatalyst having a photocatalytic activity even with visible light and an improved ultraviolet light activity, and a method for producing the same. This visible light responsive photocatalyst imparts visible light responsiveness to titanium oxide by heating titanium oxide in contact with ammonia gas or a substance that releases ammonia by heating, and then heating this in an oxidizing atmosphere. It can be manufactured.
【０００８】本発明の原料となる酸化チタンは、アナタ
ーゼ型、ルチル型、ブルッカイト型の結晶相を問わず、
また無定形の酸化チタン、水和酸化チタン、さらには硫
酸チタン、塩化チタン、硫酸チタニルなどのチタン化合
物の中和沈殿物であっても有用に使用できる。無定形の
酸化チタン、水和酸化チタン、チタン化合物の中和沈殿
物は、本発明の製造方法の加熱処理の過程で結晶化さ
れ、光触媒能の高い結晶性酸化チタンに転化される。The titanium oxide used as a raw material of the present invention may be anatase type, rutile type or brookite type crystal phase,
Further, amorphous titanium oxide, hydrated titanium oxide, and neutralized precipitates of titanium compounds such as titanium sulfate, titanium chloride, and titanyl sulfate can also be usefully used. Amorphous titanium oxide, hydrated titanium oxide, and neutralized precipitates of titanium compounds are crystallized during the heat treatment in the production method of the present invention and converted into crystalline titanium oxide having high photocatalytic activity.
【０００９】本発明の可視光応答性光触媒の製造方法と
しては、これら原料となる酸化チタンをアンモニアガス
または加熱によりアンモニアを放出する物質と接触させ
ながら加熱することにより酸化チタンに可視光応答性を
付与する工程と、こうして得られた可視光応答性酸化チ
タンを、酸化雰囲気下加熱することにより紫外光活性を
改善させる工程よりなる。In the method for producing a visible light responsive photocatalyst of the present invention, titanium oxide as a raw material is heated while being brought into contact with ammonia gas or a substance that releases ammonia by heating, so that titanium oxide has visible light responsiveness. It comprises a step of applying and a step of improving the ultraviolet light activity by heating the visible light responsive titanium oxide thus obtained in an oxidizing atmosphere.
【００１０】アンモニアガスとしては、窒素などの不活
性ガスにより希釈して使用することができる。可視光応
答性を付与するに必要なアンモニアガスの最低濃度は、
処理する酸化チタンの量、ガスの流量、処理する時間に
よっても変動するため一意的に規定することはできない
が、あまりに希薄であると可視光応答性が付与できるま
での処理時間が長くなるため、一般的には１容量％以上
であることが望ましい。アンモニアガス濃度の上限は特
に制限されず、純アンモニアガスであってもよい。しか
しながら、高濃度のアンモニアガスを使用すると熱処理
装置の排気ガスを除害する装置への負荷が高くなるた
め、工業的にはアンモニアガスを希釈して用いることが
好ましい。The ammonia gas may be diluted with an inert gas such as nitrogen before use. The minimum concentration of ammonia gas required to provide visible light response is
It cannot be uniquely specified because it varies depending on the amount of titanium oxide to be processed, the flow rate of gas, and the processing time, but if it is too dilute, the processing time until visible light responsiveness can be imparted becomes long. Generally, it is desirable that the content is 1% by volume or more. The upper limit of the ammonia gas concentration is not particularly limited and may be pure ammonia gas. However, when a high-concentration ammonia gas is used, the load on the device for removing the exhaust gas of the heat treatment device becomes high, so it is preferable to dilute the ammonia gas for industrial use.
【００１１】ガス流量としては、ガス濃度、処理時間等
によっても変動するため一意的に規定することはできな
いが、好ましくは、０．１Ｌ／ＴｉＯ2−ｋｇ・分以上
が好ましい。The gas flow rate cannot be uniquely specified because it varies depending on the gas concentration, processing time, etc., but is preferably 0.1 L / TiO 2 -kg · min or more.
【００１２】また、アンモニアガスに換えて、加熱によ
りアンモニアを放出する物質と接触させて加熱すること
によっても可視光応答性を付与することができる。加熱
によりアンモニアを放出する物質としては特に限定され
ないが、塩化アンモニウムや炭酸アンモニウムなどのア
ンモニウム塩、エタノールアミンなどのアミン類、尿素
などが挙げられる。加熱によりアンモニアを放出する物
質を用いる場合には、これらの物質と酸化チタンとを単
に一緒に加熱すればよい。Visible light responsiveness can also be imparted by heating in contact with a substance that releases ammonia by heating instead of ammonia gas. The substance that releases ammonia by heating is not particularly limited, and examples thereof include ammonium salts such as ammonium chloride and ammonium carbonate, amines such as ethanolamine, and urea. When using substances that release ammonia by heating, these substances and titanium oxide may simply be heated together.
【００１３】可視光応答性を付与する際の加熱温度は特
に限定されないが、加熱が低温であると可視光応答性の
付与が不十分となり、また逆に高温であると得られる触
媒の表面積が低下するために触媒性能は低いものとな
る。加熱温度としては、好ましくは４００℃から７００
℃、より好ましくは５００℃から６００℃の範囲で行う
ことが望ましい。The heating temperature for imparting visible light responsiveness is not particularly limited, but when the heating temperature is low, the visible light responsiveness is insufficiently imparted, and conversely when the heating temperature is high, the surface area of the catalyst obtained is high. As a result, the catalytic performance becomes low. The heating temperature is preferably 400 ° C to 700
C., more preferably in the range of 500.degree. C. to 600.degree.
【００１４】可視光応答性を付与する際の加熱時間は加
熱温度に依存するため限定することができないが、加熱
が短時間であると可視光応答性の付与が不十分となり、
また逆に長時間であると得られる触媒の表面積が低下す
るために触媒性能は低いものとなるため、具体的には、
１分〜１０時間が好ましい。より具体的には、加熱温度
５００℃では１時間から数時間、加熱温度６００℃では
数分から１時間で可視光応答性を付与することができ
る。The heating time for imparting visible light responsiveness cannot be limited because it depends on the heating temperature, but if heating is short, the visible light responsiveness is insufficiently imparted.
On the contrary, when the time is long, the surface area of the obtained catalyst is reduced and the catalyst performance is low.
1 minute to 10 hours is preferable. More specifically, visible light responsiveness can be imparted at a heating temperature of 500 ° C. for 1 hour to several hours, and at a heating temperature of 600 ° C. for several minutes to 1 hour.
【００１５】以上のようにアンモニア存在下で加熱処理
された酸化チタンは、後に比較例を挙げて示すように、
可視光応答性を有するものの紫外光による光触媒活性が
著しく低下している。本発明者はこの可視光応答性光触
媒の紫外光活性の改善について鋭意検討をおこなった結
果、可視光応答性を付与する工程に続き、これを酸化雰
囲気で加熱することにより紫外光活性を改善できること
を見出した。Titanium oxide which has been heat-treated in the presence of ammonia as described above has a
Although it has visible light responsiveness, its photocatalytic activity due to ultraviolet light is significantly reduced. The present inventor has conducted extensive studies on the improvement of the ultraviolet light activity of this visible light responsive photocatalyst, and as a result, following the step of imparting visible light responsiveness, it is possible to improve the ultraviolet light activity by heating it in an oxidizing atmosphere. Found.
【００１６】紫外光活性を改善させる工程の酸化雰囲気
中の酸素濃度は特に制限されないが、あまりに希薄であ
ると紫外光活性が改善できるまでの処理時間が長くなる
ため、一般的には酸素濃度が１容量％以上であることが
望ましい。空気中の酸素濃度で十分紫外光活性改善効果
が得られるので、特に酸素富化されたガスを用いる必要
はなく、空気中で加熱処理すればよい。ただし、加熱処
理の際に水分が存在すると酸化チタン結晶の粒成長が促
進され、得られる光触媒の表面積が低下してしまうた
め、加熱処理するガス中の水分は除去しておくことが好
ましい。The oxygen concentration in the oxidizing atmosphere in the step of improving the ultraviolet photoactivity is not particularly limited, but if it is too dilute, the treatment time until the ultraviolet photoactivity can be improved becomes long. It is preferably 1% by volume or more. Since the effect of improving the ultraviolet light activity can be sufficiently obtained by the oxygen concentration in the air, it is not necessary to use the oxygen-enriched gas, and the heat treatment may be performed in the air. However, when water is present during the heat treatment, grain growth of titanium oxide crystals is promoted and the surface area of the obtained photocatalyst is reduced, so it is preferable to remove the water in the gas to be heat treated.
【００１７】紫外光活性を改善させる工程の加熱温度は
特に限定されないが、加熱が低温であると紫外光活性の
改善が不十分となり、また逆に高温であると得られる触
媒の表面積が低下するために触媒性能は低いものとな
る。この加熱温度としては、好ましくは４００℃から７
００℃、より好ましくは５００℃から６００℃の範囲で
行うことが望ましい。また、加熱処理時間としては、具
体的には、１分〜１時間が好ましい。より具体的には、
上述のような温度で数分から１０分程度の極めて短時間
保持することにより紫外光活性の改善効果を得ることが
できる。The heating temperature in the step of improving the ultraviolet light activity is not particularly limited, but if the heating temperature is low, the improvement of the ultraviolet light activity becomes insufficient, and conversely, if the heating temperature is high, the surface area of the obtained catalyst decreases. Therefore, the catalyst performance is low. The heating temperature is preferably 400 ° C to 7
It is desirable to carry out at a temperature of 00 ° C., more preferably 500 ° C. to 600 ° C. The heat treatment time is preferably 1 minute to 1 hour. More specifically,
The effect of improving the ultraviolet photoactivity can be obtained by holding the temperature as described above for an extremely short time of about several minutes to about 10 minutes.
【００１８】更に、この際のガス流量としては、ガス濃
度、処理時間等によっても変動するため一意的に規定す
ることはできないが、好ましくは、０．１Ｌ／ＴｉＯ2
−ｋｇ・分以上が好ましい。Further, the gas flow rate at this time cannot be uniquely defined because it varies depending on the gas concentration, processing time, etc., but is preferably 0.1 L / TiO 2.
-Kg · min or more is preferable.
【００１９】紫外光活性を改善させる工程の加熱温度
は、可視光応答性を付与する工程の加熱温度と同じ温度
域であるので、可視光応答性を付与する工程に引き続き
紫外光活性を改善させる工程をおこなうことが工業的に
は好ましい。具体的には可視光応答性を付与する工程の
加熱温度を保持したままアンモニアガスに換えて酸化ガ
スを供給することにより紫外光活性の改善効果を得るこ
とができる。先に述べたように極めて短時間で紫外光活
性の改善効果を得ることができるため、実質的にはアン
モニアガス中で加熱して可視光応答性を付与した酸化チ
タンを酸化ガス雰囲気で降温することにより紫外光活性
を改善することができる。Since the heating temperature in the step of improving the ultraviolet light activity is in the same temperature range as the heating temperature in the step of imparting visible light responsiveness, the ultraviolet light activity is continuously improved after the step of imparting visible light responsiveness. It is industrially preferable to carry out the steps. Specifically, the effect of improving the ultraviolet light activity can be obtained by supplying an oxidizing gas instead of the ammonia gas while maintaining the heating temperature in the step of providing visible light responsiveness. As described above, since it is possible to obtain the effect of improving the ultraviolet photoactivity in an extremely short time, the temperature of the titanium oxide to which visible light responsiveness is imparted by heating in ammonia gas is substantially lowered in the oxidizing gas atmosphere. This can improve the ultraviolet light activity.
【００２０】なお、アンモニアガスはその濃度によって
は、高温で酸素と混合すると爆発することがあるため、
アンモニアガスに換えて酸化ガスを供給する際には、一
旦加熱処理装置内のアンモニアガスを窒素などの不活性
ガスに置換した後に酸化ガスを供給することが安全上望
ましい。It should be noted that ammonia gas may explode when mixed with oxygen at high temperature depending on its concentration.
When supplying the oxidizing gas instead of the ammonia gas, it is safer to replace the ammonia gas in the heat treatment apparatus with an inert gas such as nitrogen and then supply the oxidizing gas.
【００２１】以上のように、酸化チタンをアンモニアガ
スまたは加熱によりアンモニアを放出する物質と接触さ
せながら加熱することにより酸化チタンに可視光応答性
を付与し、次いでこれを酸化雰囲気で加熱することによ
り紫外光活性の改善された可視光応答性光触媒を得るこ
とができる。As described above, by heating titanium oxide while contacting it with ammonia gas or a substance which releases ammonia by heating, visible light responsiveness is imparted to titanium oxide, and then this is heated in an oxidizing atmosphere. A visible light responsive photocatalyst with improved ultraviolet light activity can be obtained.
【００２２】本発明の光触媒は、水やアルコールなどの
溶媒に分散させてコーティング剤を調製し、常法により
物品の表面に成膜することにより、可視光によっても紫
外光によっても高い光触媒活性を有し、屋内、屋外を問
わず、環境浄化、有害物分解、汚れの分解、抗菌、防汚
など様々な用途で有用に使用できる。The photocatalyst of the present invention is dispersed in a solvent such as water or alcohol to prepare a coating agent, and a film is formed on the surface of an article by a conventional method to obtain a high photocatalytic activity under both visible light and ultraviolet light. It can be effectively used for various purposes such as environmental purification, decomposition of harmful substances, decomposition of stains, antibacterial and antifouling indoors and outdoors.
【００２３】[0023]
【実施例】以下に実施例を用いて本発明をさらに詳しく
説明するが、本発明はこれら実施例のみに制限されるも
のではない。The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.
【００２４】実施例１
市販の酸化チタン（石原産業製、商品名「ST−０１」）
１．５ｇを流速毎分１リットルのアンモニアガス流中で
６００℃１時間熱処理し、引き続き６００℃を保持した
まま、流速毎分１リットルの窒素ガス流で２分間アンモ
ニアガスを除去後、流速毎分１リットルの空気を導入し
て空気流中６００℃で１０分間加熱処理し、このまま空
気流中で放冷して紫外光活性の改善された可視光応答性
光触媒を得た。Example 1 Commercially available titanium oxide (manufactured by Ishihara Sangyo, trade name "ST-01")
1.5 g was heat-treated at 600 ° C. for 1 hour in a flow rate of 1 liter / min of ammonia gas, and while keeping 600 ° C., the ammonia gas was removed for 2 minutes with a flow rate of 1 liter / min of nitrogen gas. A 1 liter portion of air was introduced, and the mixture was heat-treated in an air stream at 600 ° C. for 10 minutes, and then allowed to cool in the air stream to obtain a visible light responsive photocatalyst with improved ultraviolet light activity.
【００２５】実施例２
市販の酸化チタン（石原産業製、商品名「ST−０１」）
１．５ｇを流速毎分１リットルのアンモニアガス流中で
６００℃１０分間熱処理し、引き続き６００℃を保持し
たまま、流速毎分１リットルの窒素ガス流で２分間アン
モニアガスを除去後、流速毎分１リットルの空気を導入
して空気流中６００℃で５分間加熱処理し、このまま空
気流中で放冷して紫外光活性の改善された可視光応答性
光触媒を得た。Example 2 Commercially available titanium oxide (manufactured by Ishihara Sangyo, trade name "ST-01")
1.5 g was heat-treated at 600 ° C. for 10 minutes in a flow rate of 1 liter per minute of ammonia gas, and while maintaining 600 ° C., the ammonia gas was removed for 2 minutes with a flow of 1 liter of flow rate per minute of nitrogen gas. 1 liter of air was introduced and the mixture was heat-treated in an air stream at 600 ° C. for 5 minutes and allowed to cool in the air stream as it was to obtain a visible light responsive photocatalyst with improved ultraviolet light activity.
【００２６】実施例３
市販の酸化チタン（石原産業製、商品名「ST−０１」）
１．５ｇを流速毎分１リットルのアンモニアガス流中で
６００℃１０分間熱処理し、引き続き６００℃を保持し
たまま、流速毎分１リットルの窒素ガス流で２分間アン
モニアガスを除去後、流速毎分１リットルの空気を導入
して空気流中で放冷して紫外光活性の改善された可視光
応答性光触媒を得た。Example 3 Commercially available titanium oxide (manufactured by Ishihara Sangyo, trade name "ST-01")
1.5 g was heat-treated at 600 ° C. for 10 minutes in a flow rate of 1 liter per minute of ammonia gas, and while maintaining 600 ° C., the ammonia gas was removed for 2 minutes with a flow of 1 liter of flow rate per minute of nitrogen gas. A 1 liter portion of air was introduced and the mixture was allowed to cool in an air stream to obtain a visible light responsive photocatalyst with improved ultraviolet light activity.
【００２７】実施例４
市販の酸化チタン（石原産業製、商品名「ST−０１」）
１．５ｇを流速毎分１リットルのアンモニアガス流中で
６００℃１０分間熱処理し、流速毎分１リットルの窒素
ガス流中で５００℃に降温後、流速毎分１リットルの空
気を導入して空気流中５００℃で５分間加熱処理し、こ
のまま空気流中で放冷して紫外光活性の改善された可視
光応答性光触媒を得た。Example 4 Commercially available titanium oxide (manufactured by Ishihara Sangyo, trade name "ST-01")
1.5 g was heat-treated at 600 ° C. for 10 minutes in a flow rate of 1 liter / min of ammonia gas, cooled to 500 ° C. in a flow rate of 1 liter / min of nitrogen gas, and then introduced with 1 liter / min of air. The mixture was heat-treated in an air stream at 500 ° C. for 5 minutes, and allowed to cool in the air stream as it was to obtain a visible light responsive photocatalyst with improved ultraviolet light activity.
【００２８】比較例１
市販の酸化チタン（石原産業製、商品名「ST−０１」）
１．５ｇを流速毎分１リットルのアンモニアガス流中で
６００℃１０分間熱処理し、このままアンモニアガス流
中で放冷して従来法の可視光応答性光触媒を得た。Comparative Example 1 Commercially available titanium oxide (manufactured by Ishihara Sangyo, trade name "ST-01")
1.5 g was heat-treated at 600 ° C. for 10 minutes in an ammonia gas flow having a flow rate of 1 liter / min, and allowed to cool in the ammonia gas flow as it was to obtain a visible light responsive photocatalyst according to a conventional method.
【００２９】比較例２
市販の酸化チタン（石原産業製、商品名「ST−０１」）
１．５ｇを流速毎分１リットルのアンモニアガス流中で
６００℃１０分間熱処理し、流速毎分１リットルの窒素
ガス流中で放冷して従来法の可視光応答性光触媒を得
た。Comparative Example 2 Commercially available titanium oxide (manufactured by Ishihara Sangyo, trade name "ST-01")
1.5 g of the solution was heat-treated at 600 ° C. for 10 minutes in a flow rate of 1 liter / min of ammonia gas, and allowed to cool in a flow of 1 liter / min of nitrogen gas to obtain a conventional visible-light-responsive photocatalyst.
【００３０】比較例３
市販の酸化チタン（石原産業製、商品名「ST−０１」）
１．５ｇを流速毎分１リットルの窒素ガス流中で６００
℃１時間熱処理し、このまま窒素ガス流中で放冷して熱
処理した光触媒を得た。Comparative Example 3 Commercially available titanium oxide (manufactured by Ishihara Sangyo, trade name "ST-01")
600 g of 1.5 g in a nitrogen gas flow of 1 liter per minute
Heat treatment was performed at 1 ° C. for 1 hour, and the photocatalyst was heat-treated by allowing it to cool in a nitrogen gas flow.
【００３１】実施例５
上記実施例および比較例で得た光触媒５０ｍｇを直径９
ｃｍの濾紙に担持し、反応ガスとして空気で希釈した濃
度１０ｐｐｍのNOガスを流速毎分０．４リットルで流通
させて可視光および紫外光によるNO酸化反応をおこなっ
た。反応には、紫外光源としては２７Wのブラックライ
トを、可視光源としては２７Wの蛍光灯を用いた。な
お、可視光による反応では、４１０ｎｍ以下の紫外光を
吸収する紫外線カットフィルム（富士フィルム製、商品
名「UV Guard」）により紫外線を除去した光により反応
をおこなった。反応ガスの分析は、化学発光式窒素酸化
物分析計によりおこなった。Example 5 50 mg of the photocatalyst obtained in the above-mentioned Examples and Comparative Examples was used as
A NO gas having a concentration of 10 ppm diluted with air as a reaction gas was passed at a flow rate of 0.4 liter / min to carry out a NO oxidation reaction by visible light and ultraviolet light. For the reaction, a 27 W black light was used as an ultraviolet light source and a 27 W fluorescent lamp was used as a visible light source. In the reaction with visible light, the reaction was carried out with light obtained by removing ultraviolet light with an ultraviolet cut film (manufactured by Fuji Film, trade name “UV Guard”) that absorbs ultraviolet light of 410 nm or less. The reaction gas was analyzed by a chemiluminescence type nitrogen oxide analyzer.
【００３２】上記実施例および比較例で得た光触媒の可
視光および紫外光によるNO酸化反応の結果を表１および
図１に示した。結果は１時間の反応の間に転化されたNO
ｘの割合で示した。また同表中にBET１点法により測定
した実施例および比較例で得た光触媒のBET表面積も合
わせて示した。The results of NO oxidation reaction of the photocatalysts obtained in the above Examples and Comparative Examples by visible light and ultraviolet light are shown in Table 1 and FIG. The result is NO converted during the 1 hour reaction
It is shown by the ratio of x. The BET surface areas of the photocatalysts obtained in Examples and Comparative Examples measured by the BET one-point method are also shown in the table.
【００３３】[0033]
【表１】 [Table 1]
【発明の効果】表１および図１より明らかなように、熱
処理していない原料光触媒に比較して、比較例１および
２で得た従来法の可視光応答性光触媒は、紫外光による
活性が大きく低下している。紫外光による活性が低下す
る原因としては、熱処理により光触媒の表面積が低下し
ていることが挙げられる。しかしながら、可視光応答性
を付与する熱処理と同じ温度で窒素中で熱処理した比較
例３の光触媒は、やはり表面積が低下しているにもかか
わらず、なお約８０％の紫外光活性を有しており、これ
と比較しても比較例１および２で得た従来法の可視光応
答性光触媒は、紫外光活性が顕著に低下している。As is apparent from Table 1 and FIG. 1, the conventional visible light responsive photocatalysts obtained in Comparative Examples 1 and 2 have activity due to ultraviolet light as compared with the raw material photocatalyst which is not heat-treated. It has dropped significantly. The reason why the activity due to ultraviolet light is decreased is that the surface area of the photocatalyst is decreased by the heat treatment. However, the photocatalyst of Comparative Example 3, which was heat-treated in nitrogen at the same temperature as the heat treatment for imparting visible light responsiveness, still had an ultraviolet light activity of about 80% even though the surface area was reduced. However, even when compared with this, the visible light responsive photocatalysts of the conventional methods obtained in Comparative Examples 1 and 2 have remarkably reduced ultraviolet light activity.
【００３４】これに対し、本発明の方法による可視光応
答性光触媒は、従来法の可視光応答性光触媒と同等の可
視光活性を有し、かつ高い紫外光活性を維持しており、
紫外光活性が顕著に改善されている。On the other hand, the visible light responsive photocatalyst according to the method of the present invention has the same visible light activity as the visible light responsive photocatalyst of the conventional method, and maintains a high ultraviolet light activity.
The UV photoactivity is significantly improved.
【００３５】以上のように、本発明の方法によれば、可
視光によっても光触媒活性を有しかつ紫外光活性が改善
された可視光応答性光触媒を製造することができ、屋
内、屋外を問わず、環境浄化、有害物分解、汚れの分
解、抗菌、防汚など様々な用途で有用に使用できる。As described above, according to the method of the present invention, it is possible to produce a visible light responsive photocatalyst having a photocatalytic activity even with visible light and an improved ultraviolet light activity. Therefore, it can be effectively used for various purposes such as environmental purification, decomposition of harmful substances, decomposition of dirt, antibacterial and antifouling.
【図１】 実施例および比較例で得た可視光応答性光触
媒のNO酸化反応の結果を示す図である。FIG. 1 is a diagram showing the results of NO oxidation reaction of visible light responsive photocatalysts obtained in Examples and Comparative Examples.
Claims (4)
によりアンモニアを放出する物質と接触させながら加熱
することにより酸化チタンに可視光応答性を付与し、次
いでこれを酸化雰囲気で加熱することにより製造された
可視光応答性光触媒。1. A titanium oxide prepared by heating titanium oxide while contacting it with ammonia gas or a substance that releases ammonia by heating to impart visible light responsiveness to titanium oxide, and then heating it in an oxidizing atmosphere. Visible light responsive photocatalyst.
０〜７００℃である請求項１に記載の可視光応答性光触
媒。2. The temperature for heating in an oxidizing atmosphere is 40
The visible light responsive photocatalyst according to claim 1, which has a temperature of 0 to 700 ° C.
によりアンモニアを放出する物質と接触させながら加熱
することにより酸化チタンに可視光応答性を付与し、次
いでこれを酸化雰囲気で加熱することを特徴とする可視
光応答性光触媒の製造方法。3. A method of heating titanium oxide while contacting it with ammonia gas or a substance that releases ammonia by heating to impart visible light responsiveness to titanium oxide, and then heat this in an oxidizing atmosphere. Method for producing visible light responsive photocatalyst.
０〜７００℃である請求項３に記載の可視光応答性光触
媒の製造方法。4. The temperature when heating in an oxidizing atmosphere is 40
The method for producing a visible light responsive photocatalyst according to claim 3, which has a temperature of 0 to 700 ° C.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005089213A (en) * | 2003-09-16 | 2005-04-07 | Tayca Corp | Method for producing titanium oxide |
| JP2006021112A (en) * | 2004-07-07 | 2006-01-26 | Kyoto Univ | Ultraviolet and visible light responsive titania photocatalyst |
| CN1304114C (en) * | 2004-02-06 | 2007-03-14 | 华东理工大学 | Method for preparing nanometer TiO(2-x)N(x) photocatalyst and fluidized bed reactor |
| WO2007119489A1 (en) * | 2006-03-30 | 2007-10-25 | Osaka Titanium Technologies Co., Ltd. | Visible light response-type titanium oxide photocatalyst, method for manufacturing the visible light response-type titanium oxide photocatalyst, and use of the visible light response-type titanium oxide photocatalyst |
| US7651675B2 (en) | 2004-09-13 | 2010-01-26 | National Institute For Materials Science | Process for producing flaky titanium oxide capable of absorbing visible light |
-
2002
- 2002-05-30 JP JP2002158094A patent/JP2003340288A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005089213A (en) * | 2003-09-16 | 2005-04-07 | Tayca Corp | Method for producing titanium oxide |
| CN1304114C (en) * | 2004-02-06 | 2007-03-14 | 华东理工大学 | Method for preparing nanometer TiO(2-x)N(x) photocatalyst and fluidized bed reactor |
| JP2006021112A (en) * | 2004-07-07 | 2006-01-26 | Kyoto Univ | Ultraviolet and visible light responsive titania photocatalyst |
| US7153808B2 (en) | 2004-07-07 | 2006-12-26 | Kyoto University | Ultraviolet and visible-light-sensitive titania-based photocatalyst |
| US7651675B2 (en) | 2004-09-13 | 2010-01-26 | National Institute For Materials Science | Process for producing flaky titanium oxide capable of absorbing visible light |
| WO2007119489A1 (en) * | 2006-03-30 | 2007-10-25 | Osaka Titanium Technologies Co., Ltd. | Visible light response-type titanium oxide photocatalyst, method for manufacturing the visible light response-type titanium oxide photocatalyst, and use of the visible light response-type titanium oxide photocatalyst |
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