JP4146543B2 - Photocatalyst production method and hydrogen production method - Google Patents
Photocatalyst production method and hydrogen production method Download PDFInfo
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- JP4146543B2 JP4146543B2 JP08078598A JP8078598A JP4146543B2 JP 4146543 B2 JP4146543 B2 JP 4146543B2 JP 08078598 A JP08078598 A JP 08078598A JP 8078598 A JP8078598 A JP 8078598A JP 4146543 B2 JP4146543 B2 JP 4146543B2
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- 229910052739 hydrogen Inorganic materials 0.000 title claims description 33
- 239000001257 hydrogen Substances 0.000 title claims description 33
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 title claims description 31
- 238000004519 manufacturing process Methods 0.000 title claims description 31
- 239000011941 photocatalyst Substances 0.000 title description 4
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 72
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 claims description 72
- 239000003054 catalyst Substances 0.000 claims description 58
- 239000010936 titanium Substances 0.000 claims description 56
- 238000006303 photolysis reaction Methods 0.000 claims description 50
- -1 titanate compound Chemical class 0.000 claims description 36
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 32
- 230000015843 photosynthesis, light reaction Effects 0.000 claims description 28
- 229910052719 titanium Inorganic materials 0.000 claims description 22
- 150000001768 cations Chemical class 0.000 claims description 21
- 150000001875 compounds Chemical class 0.000 claims description 19
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 18
- 238000000034 method Methods 0.000 claims description 18
- 239000007864 aqueous solution Substances 0.000 claims description 15
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 10
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 9
- 229910052697 platinum Inorganic materials 0.000 claims description 9
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 8
- 238000000354 decomposition reaction Methods 0.000 claims description 8
- 238000001782 photodegradation Methods 0.000 claims description 8
- HZAXFHJVJLSVMW-UHFFFAOYSA-N 2-Aminoethan-1-ol Chemical compound NCCO HZAXFHJVJLSVMW-UHFFFAOYSA-N 0.000 claims description 6
- 229910052703 rhodium Inorganic materials 0.000 claims description 6
- 239000010948 rhodium Substances 0.000 claims description 6
- 229910052707 ruthenium Inorganic materials 0.000 claims description 6
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 claims description 4
- 229910052802 copper Inorganic materials 0.000 claims description 4
- 239000010949 copper Substances 0.000 claims description 4
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 claims description 4
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 3
- 239000003513 alkali Substances 0.000 claims description 3
- 229910052783 alkali metal Inorganic materials 0.000 claims description 3
- 229910052784 alkaline earth metal Inorganic materials 0.000 claims description 3
- 238000005341 cation exchange Methods 0.000 claims description 3
- 229910044991 metal oxide Inorganic materials 0.000 claims description 3
- 150000004706 metal oxides Chemical class 0.000 claims description 3
- 229910000480 nickel oxide Inorganic materials 0.000 claims description 3
- 230000003287 optical effect Effects 0.000 claims description 3
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 claims description 3
- 238000009830 intercalation Methods 0.000 claims description 2
- 230000001678 irradiating effect Effects 0.000 claims description 2
- 238000005336 cracking Methods 0.000 claims 1
- 239000010410 layer Substances 0.000 description 38
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 34
- 230000000052 comparative effect Effects 0.000 description 17
- 229910010413 TiO 2 Inorganic materials 0.000 description 10
- 239000000084 colloidal system Substances 0.000 description 10
- 238000005342 ion exchange Methods 0.000 description 10
- LLZRNZOLAXHGLL-UHFFFAOYSA-J titanic acid Chemical compound O[Ti](O)(O)O LLZRNZOLAXHGLL-UHFFFAOYSA-J 0.000 description 8
- 239000000243 solution Substances 0.000 description 7
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 5
- 230000003197 catalytic effect Effects 0.000 description 5
- 239000011229 interlayer Substances 0.000 description 5
- 239000004065 semiconductor Substances 0.000 description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 4
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 4
- 229910052753 mercury Inorganic materials 0.000 description 4
- 230000001699 photocatalysis Effects 0.000 description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 3
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 3
- 229910052760 oxygen Inorganic materials 0.000 description 3
- 239000001301 oxygen Substances 0.000 description 3
- 239000000843 powder Substances 0.000 description 3
- 238000005215 recombination Methods 0.000 description 3
- 230000006798 recombination Effects 0.000 description 3
- 229960000583 acetic acid Drugs 0.000 description 2
- 150000002431 hydrogen Chemical class 0.000 description 2
- 230000003301 hydrolyzing effect Effects 0.000 description 2
- 239000011812 mixed powder Substances 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 230000036962 time dependent Effects 0.000 description 2
- 239000011882 ultra-fine particle Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- QPLDLSVMHZLSFG-UHFFFAOYSA-N Copper oxide Chemical compound [Cu]=O QPLDLSVMHZLSFG-UHFFFAOYSA-N 0.000 description 1
- 239000005751 Copper oxide Substances 0.000 description 1
- 150000003973 alkyl amines Chemical class 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- 150000001735 carboxylic acids Chemical class 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 229910000431 copper oxide Inorganic materials 0.000 description 1
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- 239000012362 glacial acetic acid Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
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- 150000002500 ions Chemical group 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002736 metal compounds Chemical class 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000004570 mortar (masonry) Substances 0.000 description 1
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- GNRSAWUEBMWBQH-UHFFFAOYSA-N oxonickel Chemical compound [Ni]=O GNRSAWUEBMWBQH-UHFFFAOYSA-N 0.000 description 1
- 230000001443 photoexcitation Effects 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
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- 229920006395 saturated elastomer Polymers 0.000 description 1
- 238000010532 solid phase synthesis reaction Methods 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
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Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/36—Hydrogen production from non-carbon containing sources, e.g. by water electrolysis
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- Catalysts (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、光分解触媒の製造方法及び水素製造方法に関し、特に太陽光によって効率良く水を光分解する触媒の製造方法及び該触媒を用いた水素製造方法に関する。
【０００２】
【従来の技術及び発明が解決しようとする課題】
近年、半導体を光分解触媒として用い、水を光分解することにより水素を製造する方法が見出され、光エネルギーを化学エネルギーに変換する方法が提案されている。このように、水を水素と酸素に光分解することのできる半導体の代表的なものとして白金担持酸化チタンが知られている。しかし、この触媒を水中に懸濁して使用すると水の分解反応がすぐ停止してしまう。これは、触媒表面の白金上で逆反応である水素と酸素の再結合が進行するためと報告されている（K. Sayama, H. Arakawa, J. Chem. Soc. Chem. Commun., 150(1992).）。この逆反応を抑制する方法として、白金担持酸化チタンを層状化合物の層間に包接することが有効であり、中でも層状チタン酸化合物の層間に酸化チタン及び白金を包接した触媒は、水中懸濁状態でも長時間安定に水を光分解することができると報告されている（S. Uchida, Y. Yamamoto, Y. Hijishiro, A. Watanabe, O. Ito, T. Sato, J. Chem. Soc. Faraday Trans., 93, 3229(1997). ）。
【０００３】
酸化チタン及び白金を包接した層状チタン酸化合物の光触媒の活性は、酸化チタンの包接量の増加により向上するが、従来の包接方法によれば、１０重量％未満の包接量が限度であった。従って、従来より太陽光で効率良く水素を製造することができる光触媒が求められているが、従来の層状チタン酸化合物の触媒活性は、いまだ不十分なものであった。
【０００４】
本発明の目的は、効率良く水素を製造することができる層状チタン酸化合物を用いた光分解触媒を製造する方法及び該方法により製造された光分解触媒を用いた水素製造方法を提供することにある。
【０００５】
【課題を解決するための手段】
上記課題に鑑み鋭意研究を重ねた結果、本発明者らは、層状チタン酸化合物の層間に、チタンを含む錯陽イオンをインターカーレートした後、これを熱分解または光分解することによって、多量の酸化チタンを層間に均一に包接することができ、これを用いることによって太陽光で効率良く水を分解し、水素を製造することができることを見出し、本発明を完成するに至った。
【０００６】
すなわち、請求項１に記載の発明の光分解触媒の製造方法は、陽イオン交換性層状チタン酸化合物の層間に、チタンを含む錯陽イオンをインターカーレートした後、これを熱分解または光分解することによって、酸化チタンを層間に包接させることを特徴としている。
【０００７】
請求項２に記載の発明の光分解触媒の製造方法は、請求項１に記載の発明において、陽イオン交換性層状チタン酸化合物の層間に、１０〜５０重量％の酸化チタンを包接させることを特徴としている。
【０００８】
請求項３に記載の発明は、請求項１に記載の発明及び請求項２に記載の発明において、チタンを含む錯陽イオンが、チタンアシル錯体の陽イオンであることを特徴としている。
【０００９】
請求項４に記載の発明は、請求項１に記載の発明において、陽イオン交換性層状チタン酸化合物の層間に包接された酸化チタンが、助触媒を担持していることを特徴としている。
【００１０】
請求項５に記載の発明は、上記助触媒が、白金、ルテニウム、ロジウム、銅、ニッケル及びこれらの金属酸化物からなる群より選ばれる少なくとも一種であることを特徴としている。
請求項６に記載の発明は、上記助触媒の担持量が、光分解触媒全体に対して０．０１〜５重量％であることを特徴としている。
【００１１】
請求項７に記載の発明は、請求項１に記載の発明において、陽イオン交換性層状チタン酸化合物が、Ｈ2 Ｔｉ2 Ｏ5 、Ｈ2 Ｔｉ3 Ｏ7 、Ｈ2 Ｔｉ4 Ｏ9 、Ｈ2 Ｌａ2 Ｔｉ3 Ｏ10、ＨＴｉＮｂＯ5 、及びこれらのアルカリ金属塩及びアルカリ土類金属塩からなる群より選ばれる少なくとも一種の化合物であることを特徴としている。
【００１２】
請求項８に記載の発明は、水素を製造する方法に関するものであり、光分解の対象となる水溶液に、上記本発明の光分解触媒を添加し、これに光を照射することによって分解し、水素を製造することを特徴としている。
【００１３】
請求項９に記載の発明は、上記光分解の対象となる水溶液が還元性化合物を含有していることを特徴としている。
請求項１０に記載の発明は、上記還元性化合物が、アルカリ化合物及び／またはアルコールであることを特徴としている。
【００１４】
請求項１１に記載の発明は、上記還元性化合物が、Ｎａ2 Ｓ、Ｎａ2 ＳＯ3 、Ｎａ2 Ｓ2 Ｏ3 、ＮａＮＯ2 、メタノール、エタノール、プロパノール、及び２−アミノエタノールからなる群より選ばれる少なくとも一種の化合物であることを特徴としている。
【００１５】
【発明の実施の形態】
以下、本発明を詳細に説明する。
（１）光分解触媒の構成
本発明の光分解触媒は、酸化チタン半導体（ａ）を層状チタン酸化合物（ｂ）の層間に包接してなる光分解触媒である。
【００１６】
（ａ）酸化チタン半導体
本発明の光分解触媒においては、上述のように、層状チタン酸化合物（ｂ）の層間に、チタンを含む錯陽イオンをインターカーレートした後、これを熱分解または光分解することによって酸化チタンを層間に生成させている。このため、多量の酸化チタンを均一に層間に包接させることができる。
【００１７】
チタンを含む錯陽イオンとしては、例えば、チタンアシル錯体の陽イオン（〔Ｔｉ（ＯＡｃ）x （ＯＨ）y 〕Z+）が挙げられる。また、チタンを含む錯陽イオンとして、その他クエン酸などのカルボン酸を用いた錯体の陽イオンが挙げられる。
【００１８】
層間に包接される酸化チタン半導体は、酸化チタン単独であってもよいが、酸化チタンに助触媒を担持させたものであってもよい。助触媒を酸化チタンに担持させる方法としては、後述するように、助触媒または助触媒の前駆体を、予め層状チタン酸化合物の層間に包接させ、その後酸化チタンを層間に包接し、酸化チタンの表面近傍に助触媒を存在させる方法が挙げられる。しかしながら、本発明において、助触媒を酸化チタンに担持させる方法は、このような方法に限定されるものではなく、その他の方法によって酸化チタンの表面近傍に担持させてもよい。
【００１９】
助触媒としては、例えば、白金、ルテニウム、ロジウム、銅、ニッケルなどの金属あるいはこれらの金属酸化物を用いることができる。より好ましくは、白金元素、ルテニウム元素、ロジウム元素、銅酸化物、及びニッケル酸化物からなる群より選ばれる少なくとも一種が用いられる。好ましい助触媒の担持量は、酸化チタンに対し０．０５〜１５重量％であり、光分解触媒全体に対して０．０１〜５重量％である。
【００２０】
酸化チタンは、太陽光等の光で励起され、電子と正孔を生成し、層状チタン酸化合物への電子移動が起こり、電荷分離が起こることによって、水分解の触媒活性を示す。酸化チタンに助触媒を担持させることにより、電子と正孔との再結合が抑制され、光分解触媒活性が向上する。
【００２１】
本発明においては、層状チタン酸化合物（ｂ）の層間に酸化チタンを包接している。酸化チタン単独では、超微粒子化すると、バンドギャップが増加し、太陽光を利用できなくなったり、水中懸濁時に逆反応が起こる等問題が生じるが、層状チタン酸化合物の層間に包接することにより、このような問題を解消することができる。
【００２２】
（ｂ）層状チタン酸化合物
本発明における層状チタン酸化合物は、層状の格子間に有する陽イオンを、化合物の外部の陽イオンとイオン交換できるものであれば如何なるものでもよいが、具体的には、Ｈ2 Ｔｉ2 Ｏ5 、Ｈ2 Ｔｉ3 Ｏ7 、Ｈ2 Ｔｉ4 Ｏ9 、Ｈ2 Ｌａ2 Ｔｉ3 Ｏ10、ＨＴｉＮｂＯ5 、及びこれらのアルカリ金属塩及びアルカリ土類金属塩等が挙げられ、特にＨ2 Ｔｉ2 Ｏ5 、Ｈ2 Ｔｉ3 Ｏ7 、Ｈ2 Ｔｉ4 Ｏ9 が好ましい。
【００２３】
（２）光分解触媒の製造方法
本発明の光分解触媒の製造方法を、以下に例を挙げて説明する。
助触媒の包接
層状チタン酸化合物を、〔Ｐｔ（ＮＨ3 ）4 〕Ｃｌ2 等のＰｔ、Ｒｕ、Ｒｈ、Ｃｕ、Ｎｉ化合物水溶液に懸濁し、層間にＰｔ（ＮＨ3 ）4 2+を包接させた後、ＵＶ光を０．５〜１００時間照射して、Ｐｔ、Ｒｕ、Ｒｈ等の元素を層間に析出させる。Ｒｕ、Ｃｕ、Ｎｉ酸化物を包接させる場合には、層間に包接した金属化合物を加水分解あるいは脱水する方法を用いる。
【００２４】
酸化チタンの包接
層状チタン酸化合物、またはＰｔ等の助触媒を包接した層状チタン酸化合物を、ｎ−ヘキサン等の有機溶媒または水中に分散させた後、ｎ−Ｃ8 Ｈ17ＮＨ2 やｎ−Ｃ3 Ｈ7 ＮＨ2 等のアルキルアミンを添加し、室温以上かつ溶媒の沸点未満の温度で１〜２４０時間反応させ、層間の陽イオンをアルキルアンモニウムイオンとイオン交換する。得られたアルキルアンモニウムイオン含有層状チタン酸化合物を、Ｔｉ（ｉ−Ｃ3 Ｈ7 Ｏ）4 と酢酸の反応等により得られたチタンアシル錯体（〔Ｔｉ（ＯＡｃ）x （ＯＨ）y 〕z+）溶液に加えて、室温から９０℃で１〜２４０時間反応させ、層間にチタンアシル錯体を包接させ、次にＵＶ光を０．５〜５０時間照射するか、あるいは２５０〜６００℃の温度で１〜５時間熱処理して、酸化チタン、または白金等の助触媒を担持した酸化チタンを層状チタン酸化合物に包接した光分解触媒を得る。
【００２５】
以上の製造方法等により得られる本発明の光分解触媒は、層間に包接された酸化チタン粒子の粒子径が１．０ｎｍ以下の超微粒子であり、大きな比表面積と優れた触媒活性を有しながら、バンドギャップは小さく（３ｅＶ）、太陽光を利用した水の光分解に好適な光分解触媒である。また、従来の酸化チタンコロイドを用いて酸化チタンを包接したものと比較して、多量の酸化チタンを均一に層間に包接できるため、優れた光触媒活性を有している。
なお、上記の製造方法は、本発明の光分解触媒の製造方法の一例であり、本発明の光分解触媒は、上記製造方法に限定されるものではない。
【００２６】
上記本発明の光分解触媒を使用した本発明の水素の製造方法を以下説明する。
光分解の対象となる水溶液は、純水（不純物を含まない意味ではなく、正孔と反応する有機物のような犠牲還元剤が添加されていない水を意味する）でもよいが、好ましくは、アルカリ化合物水溶液やアルコール水溶液、あるいはこれらの混合水溶液のような、還元性化合物が添加された水溶液を使用する。アルカリ化合物としては、Ｎａ2 Ｓ、Ｎａ2 ＳＯ3 、Ｎａ2 Ｓ2 Ｏ3 、ＮａＮＯ2 等が好ましく、これらの混合物であってもよい。濃度は、０．０１〜１ｍｏｌ／リットルが好ましい。また、アルコールとしては、メタノール、エタノール、プロパノール、２−アミノエタノール等が好ましく、これらの混合物であってもよい。濃度は０．０１〜１ｍｏｌ／リットルが好ましい。
【００２７】
上記水溶液に、本発明の光分解触媒を添加する。光分解触媒の添加量は、０．５〜５０ｍｇ／ｃｍ3 が好ましく、特に１〜３ｍｇ／ｃｍ3 が好ましい。このように光分解触媒を添加した水溶液に光を照射することによって水が分解し、水素が発生する。照射する光の波長は４５０ｎｍ以下が好ましい。太陽光の波長は３５０〜２０００ｎｍ程度であるため、本発明では太陽光を照射してもよい。また水溶液の温度は２５〜６０℃が好ましい。
【００２８】
（作用）
上述したように、本発明の光分解触媒は、酸化チタンを層状チタン酸化合物に包接したものであるので、バンドギャップは２．８〜３．３ｅＶであり、３７５〜４４０ｎｍ程度の波長の光の照射により励起して、水の光分解に対する高い触媒活性を示す。これは、超微粒子の酸化チタンが光励起されて生成する電子が、酸化チタンを包接している層状チタン酸化合物に移動することにより、電荷分離が有効に起こり、電子と正孔の再結合が抑制されるためと考えられる。また、本発明の光分解触媒は、水溶液中でもほとんど溶解することがなく、化学的に安定している。
【００２９】
また、本発明の光分解触媒は、チタンアシル錯体のようなチタンを含む錯陽イオンを用いて酸化チタンを包接させたものであるので、従来の酸化チタンコロイドを用いて酸化チタンを包接したものに比べ、高濃度の酸化チタンが層間に均一に包接される。このため、従来に比べ遙かに効率良く水を光分解し、水素を製造することができる。従来のように酸化チタンコロイドを用いて層間に酸化チタンを包接させると、酸化チタンが層間に無秩序に包接される。これに対して、本発明のようにチタンを含む錯陽イオンを用いると、錯陽イオンがイオン交換反応により層間に容易に包接され、しかもチタン酸化合物との静電的相互作用により層間に均一に分布する。このため、高濃度の酸化チタンを均一に層間に包接させることができる。
【００３０】
【実施例】
本発明を以下の具体的実施例によりさらに詳細に説明する。
実施例１
固相法により合成した層状チタン酸Ｋ2 Ｔｉ4 Ｏ9 の粉末を３０℃の１Ｍ塩酸水溶液に３０分間分散し、層状チタン酸Ｈ2 Ｔｉ4 Ｏ9 を得た。これを、〔Ｐｔ（ＮＨ3 ）4 〕Ｃｌ2 水溶液（イオン交換すべき量の２０倍の〔Ｐｔ（ＮＨ3 ）4 〕Ｃｌ2 を含有）に懸濁し、層間に〔Ｐｔ（ＮＨ3 ）4 〕2+を包接した後、４５０Ｗの水銀灯の光を１時間照射して、層間にＰｔを析出させた。これを水に分散させ、Ｈ2 Ｔｉ4 Ｏ9 のイオン交換量の１０倍量のｎ−Ｃ3 Ｈ7 ＮＨ2 を添加し、２５℃で４日間反応させ、層間のＨ+ をｎ−Ｃ3 Ｈ7 ＮＨ3 + とイオン交換した。
【００３１】
Ｔｉ（ｉ−Ｃ3 Ｈ7 Ｏ）4 に５倍のモルの氷酢酸を加え３０分間攪拌し、Ｔｉ（ＣＨ3 ＣＯ）x （ｉ−Ｃ3 Ｈ7 Ｏ）y 錯体を調製した後、この溶液に５倍量の水を加え、１時間攪拌し、Ｔｉ（ＣＨ3 ＣＯ）x （ＯＨ）y z+を調製した。この溶液に、ｎ−Ｃ3 Ｈ7 ＮＨ3 + をイオン交換した層状チタン酸を懸濁し（層状チタン酸／Ｔｉ（ＣＨ3 ＣＯ）x （ＯＨ）y z+モル比＝４０）、室温で５〜１５０時間反応させて層間のｎ−Ｃ3 Ｈ7 ＮＨ3 + をＴｉ（ＣＨ3 ＣＯ）x （ＯＨ）y z+とイオン交換し、ろ過分離後、試料を水に再分散し、４５０Ｗの水銀灯の光を１０時間照射して、層間にＰｔを担持した酸化チタンを包接した光分解触媒を調製した。この光分解触媒の酸化チタン包接量は、Ｔｉ（ＣＨ3 ＣＯ）x （ＯＨ）y z+とのイオン交換時間と共に増加し、１４４時間で２６重量％−ＴｉＯ2 であった。この時の酸化チタン包接量の経時変化を図１に示す。
【００３２】
比較例１
Ｔｉ（ｉ−Ｃ3 Ｈ7 Ｏ）4 を１Ｍ塩酸に加えて加水分解して得られたＴｉＯ2 ゾルの透明溶液にｎ−Ｃ3 Ｈ7 ＮＨ3 + をイオン交換した上記の層状チタン酸を懸濁し（層状チタン酸／ＴｉＯ2 モル比＝４０）、室温で１〜１２０時間反応させて層間に酸化チタンコロイドを包接し、ろ過分離後、試料を水に再分散し、４５０Ｗの水銀灯の光を１０時間照射して、層間にＰｔを担持した酸化チタンを包接した光分解触媒を調製した。この光分解触媒の酸化チタン包接量は、イオン交換時間１０時間で飽和し、８．１重量％−ＴｉＯ2 であった。この時の酸化チタン包接量の経時変化を図１に示す。
【００３３】
図１から明らかなように、ＴｉＯ2 コロイド溶液を用いた酸化チタン包接法では、酸化チタン包接量が１０重量％−ＴｉＯ2 以下で頭打ちになるが、本発明によるチタンアシル錯体を用いた酸化チタン包接法では、酸化チタン包接量を大幅に向上することが可能であった。
【００３４】
実施例２
実施例１で得られた光分解触媒０．５ｇを、純水１４００ｃｍ3 に添加し、４５０Ｗの水銀灯の光を照射した。光照射により水の完全光分解が起こり、酸素と水素の生成量は１：２であった。この時の水素の生成量を図２に示す。
【００３５】
比較例２
比較例１で得られた光分解触媒０．５ｇを用いて実施例２と同じ方法で水の光分解性能を測定した。この時の水素の生成量を図２に示す。
【００３６】
比較例３
層状チタン酸Ｈ2 Ｔｉ4 Ｏ9 に、市販の酸化チタン（デグサ社製「Ｐ−２５」）に０．１重量％のＰｔを担持したものを２０重量％乳鉢で混合し、層状チタン酸＋Ｐｔ担持酸化チタン混合粉末を得た。この粉末０．５ｇを用いて実施例２と同じ方法で水の光分解性能を測定した。この時の水素の生成量を図２に示す。
【００３７】
図２から明らかなように、層状チタン酸＋Ｐｔ担持酸化チタン混合粉末を用いた比較例３では、水の分解が全く進行しなかったのに対し、Ｐｔ担持酸化チタンを層状チタン酸の層間に包接した光分解触媒を用いた実施例２及び比較例２では、安定した水素の生成がみられた。また、本発明によるチタンアシル錯体を用いてＰｔ担持酸化チタンを包接した光触媒を用いた実施例２の方が、ＴｉＯ2 コロイドを用いた比較例２より、水の分解速度が約１．５倍速かった。
【００３８】
実施例３
助触媒であるＰｔを担持しない以外は実施例１と同じように、チタンアシル錯体を用いて酸化チタンをＨ2 Ｔｉ4 Ｏ9 の層間に包接した光分解触媒を調製した。この触媒０．５ｇを用いて実施例２と同じ方法で水の光分解性能を測定した。Ｐｔを担持せず酸化チタンのみを包接した触媒でも水の分解が起こった。この時の水素の生成量を図３に示す。
【００３９】
比較例４
助触媒であるＰｔを担持しない以外は比較例１と同じように、ＴｉＯ2 コロイド溶液を用いて酸化チタンをＨ2 Ｔｉ4 Ｏ9 の層間に包接した光分解触媒を調製した。この触媒０．５ｇを用いて実施例２と同じ方法で水の光分解性能を測定した。この時の水素の生成量を図３に示す。
【００４０】
比較例５
層状チタン酸Ｈ2 Ｔｉ4 Ｏ9 ０．５ｇを用いて実施例２と同じ方法で水の光分解性能を測定した。この時の水素の生成量を図３に示す。
【００４１】
図３から明らかなように、層状チタン酸Ｈ2 Ｔｉ4 Ｏ9 粉末を用いた比較例５では、水の分解が全く進行しなかったのに対し、酸化チタンを層状チタン酸Ｈ2 Ｔｉ4 Ｏ9 の層間に包接した光分解触媒を用いた実施例３及び比較例４では、安定した水素の生成がみられた。また、本発明によるチタンアシル錯体を用いてＰｔ担持酸化チタンを包接した光触媒を用いた実施例３の方が、ＴｉＯ2 コロイドを用いた比較例４より、水の分解速度が約２倍速かった。
【００４２】
図２及び図３から分かるように、本発明によるチタンアシル錯体を用いて酸化チタンを包接した触媒による実施例２及び３の水素生成量は、ＴｉＯ2 コロイドを用いて酸化チタンを包接した触媒による比較例２及び４に比して高く、良好な光分解特性を有することを示した。
【００４３】
【発明の効果】
請求項１〜８に記載の発明によれば、超微粒子の酸化チタンを高濃度で均一に層状チタン酸化合物の層間に包接させた光分解触媒とすることができ、優れた光触媒活性を付与することができる。
【００４４】
また、請求項５〜７に記載の発明に従い層間に包接された酸化チタンに助触媒を担持させることにより、さらに光触媒活性を高めることができる。
請求項９〜１２に記載の発明によれば、上記本発明の光分解触媒を用いることにより、効率良く水を光分解し、水素を製造することができる。
【図面の簡単な説明】
【図１】実施例１及び比較例１における酸化チタン包接量を示す図である。
【図２】実施例２及び比較例２，３における水素生成量を示す図である。
【図３】実施例３及び比較例４，５における水素生成量を示す図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing及beauty Hydrogen production method of photolysis catalyst, particularly efficient process for hydrogen production using the manufacturing method and the catalyst of the optical decomposing catalyst the water by sunlight.
[0002]
[Prior art and problems to be solved by the invention]
In recent years, a method of producing hydrogen by photodegrading water using a semiconductor as a photolysis catalyst has been found, and a method of converting light energy into chemical energy has been proposed. Thus, platinum-supported titanium oxide is known as a typical semiconductor capable of photolyzing water into hydrogen and oxygen. However, when this catalyst is suspended in water and used, the decomposition reaction of water stops immediately. This is reported to be due to the recombination of hydrogen and oxygen, which is a reverse reaction, on platinum on the catalyst surface (K. Sayama, H. Arakawa, J. Chem. Soc. Chem. Commun., 150 ( 1992).). As a method for suppressing this reverse reaction, it is effective to include platinum-supported titanium oxide between the layers of the layered compound, and in particular, the catalyst in which titanium oxide and platinum are included between the layers of the layered titanate compound is suspended in water. However, it has been reported that water can be photodegraded stably for a long time (S. Uchida, Y. Yamamoto, Y. Hijishiro, A. Watanabe, O. Ito, T. Sato, J. Chem. Soc. Faraday Trans., 93, 3229 (1997).).
[0003]
The photocatalytic activity of the layered titanate compound containing titanium oxide and platinum is improved by increasing the inclusion amount of titanium oxide. However, according to the conventional inclusion method, the inclusion amount is less than 10% by weight. Met. Therefore, a photocatalyst capable of producing hydrogen efficiently with sunlight has been demanded, but the catalytic activity of the conventional layered titanate compound is still insufficient.
[0004]
An object of the present invention is to provide a method for producing hydrogen using efficient photolysis catalyst produced by the process and method for producing the photodegradation catalyst using layered titanic acid compound capable of producing hydrogen is there.
[0005]
[Means for Solving the Problems]
As a result of intensive studies in view of the above problems, the present inventors intercalated a complex cation containing titanium between layers of a layered titanate compound, and then thermally decomposed or photodecomposed this to produce a large amount. It was found that titanium oxide can be uniformly clad between the layers, and by using this, water can be efficiently decomposed by sunlight to produce hydrogen, and the present invention has been completed.
[0006]
That is, in the method for producing a photolysis catalyst according to the first aspect of the present invention, a complex cation containing titanium is intercalated between layers of a cation-exchange layered titanate compound, and then this is thermally decomposed or photodecomposed. by, it is characterized by Ru to inclusion of titanium oxide in layers.
[0007]
The method of manufacturing an optical decomposition catalyst of the invention recited in
[0008]
The invention described in
[0009]
Invention according to
[0010]
The invention according to
The invention described in claim 6 is characterized in that the amount of the cocatalyst supported is 0.01 to 5% by weight with respect to the entire photodecomposition catalyst.
[0011]
The invention according to claim 7, Oite the inventions of
[0012]
The invention according to claim 8 relates to a method for producing hydrogen, wherein the photodecomposition catalyst of the present invention is added to an aqueous solution to be subjected to photodecomposition and decomposed by irradiation with light. It is characterized by producing hydrogen.
[0013]
The invention according to claim 9 is characterized in that the aqueous solution to be subject to photolysis contains a reducing compound.
The invention according to
[0014]
The invention according to claim 11 is such that the reducing compound is selected from the group consisting of Na 2 S, Na 2 SO 3 , Na 2 S 2 O 3 , NaNO 2 , methanol, ethanol, propanol, and 2-aminoethanol. It is characterized by being at least one kind of compound.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
(1) Structure of photodecomposition catalyst The photodecomposition catalyst of the present invention is a photodecomposition catalyst formed by including a titanium oxide semiconductor (a) between layers of a layered titanate compound (b).
[0016]
(A) Titanium oxide semiconductor In the photolysis catalyst of the present invention, as described above, after intercalating a complex cation containing titanium between the layers of the layered titanate compound (b), Titanium oxide is generated between the layers by pyrolysis or photolysis. For this reason, a large amount of titanium oxide can be uniformly included between the layers.
[0017]
Examples of the complex cation containing titanium include a cation ([Ti (OAc) x (OH) y ] Z + ) of a titanium acyl complex. In addition, examples of complex cations containing titanium include cations of complexes using other carboxylic acids such as citric acid.
[0018]
The titanium oxide semiconductor clathrated between the layers may be titanium oxide alone or may be one in which a promoter is supported on titanium oxide. As a method for supporting the cocatalyst on the titanium oxide, as described later, the cocatalyst or the precursor of the cocatalyst is previously included between the layers of the layered titanate compound, and then the titanium oxide is included between the layers. The method of making a cocatalyst exist in the surface vicinity of this is mentioned. However, in the present invention, the method for supporting the cocatalyst on titanium oxide is not limited to such a method, and it may be supported near the surface of titanium oxide by other methods.
[0019]
As the promoter, for example, a metal such as platinum, ruthenium, rhodium, copper, nickel, or a metal oxide thereof can be used. More preferably, at least one selected from the group consisting of platinum element, ruthenium element, rhodium element, copper oxide, and nickel oxide is used. A preferable amount of the cocatalyst supported is 0.05 to 15% by weight with respect to titanium oxide, and 0.01 to 5% by weight with respect to the entire photodegradation catalyst.
[0020]
Titanium oxide is excited by light such as sunlight, generates electrons and holes, causes electron transfer to the layered titanate compound, and exhibits charge separation, thereby showing water splitting catalytic activity. By supporting the cocatalyst on titanium oxide, recombination of electrons and holes is suppressed, and the photolysis catalytic activity is improved.
[0021]
In the present invention, titanium oxide is included between the layers of the layered titanate compound (b). In the case of titanium oxide alone, when it becomes ultrafine particles, the band gap increases, sun light cannot be used, and problems such as reverse reaction occur when suspended in water, but by inclusion between the layers of layered titanate compound, Such a problem can be solved.
[0022]
(B) Layered titanate compound The layered titanate compound in the present invention may be any one as long as it can ion-exchange the cation between the layered lattices with a cation outside the compound, Specifically, H 2 Ti 2 O 5 , H 2 Ti 3 O 7 , H 2 Ti 4 O 9 , H 2 La 2 Ti 3 O 10 , HTiNbO 5 , and alkali metal salts and alkaline earth metal salts thereof. H 2 Ti 2 O 5 , H 2 Ti 3 O 7 , and H 2 Ti 4 O 9 are particularly preferable.
[0023]
(2) Method for Producing Photolytic Catalyst The method for producing the photolytic catalyst of the present invention will be described below with reference to examples.
The inclusion <br/> layered titanic acid compound cocatalyst, [Pt (NH 3) 4] Pt 2 such Cl, suspended Ru, Rh, Cu, a Ni compound aqueous solution, Pt (NH 3) in an interlayer 4 After the inclusion of 2+ , UV light is irradiated for 0.5 to 100 hours to deposit elements such as Pt, Ru, Rh, etc. between the layers. When inclusion of Ru, Cu, or Ni oxide, a method of hydrolyzing or dehydrating a metal compound included between layers is used.
[0024]
After inclusion <br/> layered titanic acid compound of titanium oxide, or a layered titanic acid compound clathrate cocatalysts such as Pt, dispersed in an organic solvent or in water, such as n- hexane, n-C 8 H Alkylamine such as 17 NH 2 and n-C 3 H 7 NH 2 is added and reacted at a temperature of room temperature or higher and lower than the boiling point of the solvent for 1 to 240 hours to ion-exchange the cations between the layers with alkyl ammonium ions. Titanium acyl complex ([Ti (OAc) x (OH) y ] z + ) solution obtained by reacting the obtained alkylammonium ion-containing layered titanic acid compound with Ti (i-C 3 H 7 O) 4 and acetic acid, etc. In addition to reacting at room temperature to 90 ° C. for 1 to 240 hours, the titanium acyl complex is included between the layers, and then irradiated with UV light for 0.5 to 50 hours, or at a temperature of 250 to 600 ° C. for 1 to 2 hours. Heat treatment is performed for 5 hours to obtain a photodecomposition catalyst in which titanium oxide or titanium oxide supporting a promoter such as platinum is included in a layered titanate compound.
[0025]
The photodecomposition catalyst of the present invention obtained by the above production method is an ultrafine particle having a particle size of titanium oxide particles included between layers of 1.0 nm or less, and has a large specific surface area and excellent catalytic activity. However, the band gap is small (3 eV), and it is a photolysis catalyst suitable for photolysis of water using sunlight. In addition, compared with a conventional titanium oxide colloid using a titanium oxide colloid, a large amount of titanium oxide can be uniformly clad between layers, and thus has excellent photocatalytic activity.
In addition, said manufacturing method is an example of the manufacturing method of the photolysis catalyst of this invention, and the photolysis catalyst of this invention is not limited to the said manufacturing method.
[0026]
The method for producing hydrogen of the present invention using the photodecomposition catalyst of the present invention will be described below.
The aqueous solution to be subjected to photolysis may be pure water (not meaning that it does not contain impurities, but water that does not contain a sacrificial reducing agent such as an organic substance that reacts with holes). An aqueous solution to which a reducing compound is added, such as a compound aqueous solution, an alcohol aqueous solution, or a mixed aqueous solution thereof, is used. As the alkali compound, Na 2 S, Na 2 SO 3 , Na 2 S 2 O 3 , NaNO 2 and the like are preferable, and a mixture thereof may be used. The concentration is preferably from 0.01 to 1 mol / liter. Moreover, as alcohol, methanol, ethanol, propanol, 2-aminoethanol etc. are preferable, and these may be sufficient. The concentration is preferably from 0.01 to 1 mol / liter.
[0027]
The photolysis catalyst of the present invention is added to the aqueous solution. The addition amount of the photodegradation catalyst is preferably 0.5 to 50 mg / cm 3, in particular 1-3 mg / cm 3 are preferred. Thus, by irradiating light to the aqueous solution to which the photolysis catalyst is added, water is decomposed and hydrogen is generated. The wavelength of the irradiated light is preferably 450 nm or less. Since the wavelength of sunlight is about 350 to 2000 nm, sunlight may be irradiated in the present invention. The temperature of the aqueous solution is preferably 25 to 60 ° C.
[0028]
(Function)
As described above, since the photodecomposition catalyst of the present invention includes titanium oxide in a layered titanate compound, the band gap is 2.8 to 3.3 eV, and light having a wavelength of about 375 to 440 nm. Exhibits high catalytic activity for water photolysis. This is because electrons generated by photoexcitation of ultrafine titanium oxide move to the layered titanate compound that includes titanium oxide, thereby effectively separating charges and suppressing recombination of electrons and holes. It is thought to be done. In addition, the photodecomposition catalyst of the present invention hardly chemically dissolves in an aqueous solution and is chemically stable.
[0029]
In addition, since the photolysis catalyst of the present invention includes titanium oxide using a complex cation containing titanium such as a titanium acyl complex, the titanium oxide is included using a conventional titanium oxide colloid. Compared to those, high-concentration titanium oxide is uniformly included between the layers. For this reason, water can be photolyzed and hydrogen can be produced much more efficiently than before. When titanium oxide is clad between layers using a titanium oxide colloid as in the prior art, the titanium oxide is randomly clasped between the layers. On the other hand, when a complex cation containing titanium is used as in the present invention, the complex cation is easily included between the layers by an ion exchange reaction, and moreover, between the layers by electrostatic interaction with the titanate compound. Evenly distributed. For this reason, high concentration titanium oxide can be uniformly included between the layers.
[0030]
【Example】
The invention is illustrated in more detail by the following specific examples.
Example 1
The layered titanate K 2 Ti 4 O 9 powder synthesized by the solid phase method was dispersed in a 1 M hydrochloric acid aqueous solution at 30 ° C. for 30 minutes to obtain layered titanate H 2 Ti 4 O 9 . This, [Pt (NH 3) 4] Cl 2 solution was suspended in (20 times the amount to be ion-exchange [Pt (NH 3) 4] Cl 2 containing), [Pt (NH 3) in an interlayer 4 After inclusion of 2+ , light from a 450 W mercury lamp was irradiated for 1 hour to deposit Pt between the layers. This was dispersed in water, was added H 2 Ti 4 ion exchange capacity of 10 times the n-C 3 H 7 NH 2 in O 9, and reacted for 4 days at 25 ° C., the H + of the interlayer n-C Ion exchanged with 3 H 7 NH 3 + .
[0031]
After adding 5 times mole of glacial acetic acid to Ti (i-C 3 H 7 O) 4 and stirring for 30 minutes to prepare a Ti (CH 3 CO) x (i-C 3 H 7 O) y complex, 5 volumes of water was added to the solution, stirred for 1 hour to prepare a Ti (CH 3 CO) x ( OH) y z +. To this solution, n-C 3 H 7 NH 3 + was suspended layered titanic acid ion exchange (layered titanic acid / Ti (CH 3 CO) x (OH) y z + molar ratio = 40), 5 at
[0032]
Comparative Example 1
The layered titanic acid obtained by ion exchange of n-C 3 H 7 NH 3 + was added to a transparent solution of TiO 2 sol obtained by adding Ti (i-C 3 H 7 O) 4 to 1M hydrochloric acid and hydrolyzing it. Suspended (layered titanic acid / TiO 2 molar ratio = 40), reacted at room temperature for 1 to 120 hours to enclose the titanium oxide colloid between the layers, filtered and separated, then redispersed the sample in water, 450 W mercury lamp light Was irradiated for 10 hours to prepare a photolysis catalyst including titanium oxide carrying Pt between the layers. The amount of titanium oxide included in the photodecomposition catalyst was saturated at an ion exchange time of 10 hours and was 8.1 wt% -TiO 2 . The time-dependent change of the titanium oxide inclusion amount at this time is shown in FIG.
[0033]
As can be seen from FIG. 1, in the titanium oxide clathration method using a TiO 2 colloid solution, the titanium oxide clathrate reaches a peak when it is 10 wt% -TiO 2 or less. However, the oxidation using the titanium acyl complex according to the present invention. In the titanium clathration method, it was possible to greatly improve the amount of titanium oxide clathrate.
[0034]
Example 2
0.5 g of the photodegradation catalyst obtained in Example 1 was added to 1400 cm 3 of pure water, and irradiated with light from a 450 W mercury lamp. The photoirradiation caused complete photolysis of water, and the amount of oxygen and hydrogen produced was 1: 2. The amount of hydrogen produced at this time is shown in FIG.
[0035]
Comparative Example 2
The photolysis performance of water was measured by the same method as in Example 2 using 0.5 g of the photolysis catalyst obtained in Comparative Example 1. The amount of hydrogen produced at this time is shown in FIG.
[0036]
Comparative Example 3
The layered titanic acid H 2 Ti 4 O 9 was mixed with a commercially available titanium oxide (“P-25” manufactured by Degussa) carrying 0.1% by weight of Pt in a 20% by weight mortar, and the layered titanic acid + Pt A supported titanium oxide mixed powder was obtained. Using 0.5 g of this powder, the photolysis performance of water was measured in the same manner as in Example 2. The amount of hydrogen produced at this time is shown in FIG.
[0037]
As is clear from FIG. 2, in Comparative Example 3 using the layered titanic acid + Pt-supported titanium oxide mixed powder, the decomposition of water did not proceed at all, whereas the Pt-supported titanium oxide was encapsulated between the layered titanate layers. In Example 2 and Comparative Example 2 using the photodecomposition catalyst in contact, stable hydrogen production was observed. Further, in Example 2 using the photocatalyst in which Pt-supported titanium oxide was included using the titanium acyl complex according to the present invention, the water decomposition rate was about 1.5 times faster than Comparative Example 2 using TiO 2 colloid. won.
[0038]
Example 3
A photodecomposition catalyst in which titanium oxide was included between H 2 Ti 4 O 9 layers using a titanium acyl complex was prepared in the same manner as in Example 1 except that Pt as a cocatalyst was not supported. The photodecomposition performance of water was measured by the same method as in Example 2 using 0.5 g of this catalyst. Water decomposition also occurred in the catalyst that did not support Pt and included only titanium oxide. The amount of hydrogen produced at this time is shown in FIG.
[0039]
Comparative Example 4
A photodecomposition catalyst in which titanium oxide was included between H 2 Ti 4 O 9 layers using a TiO 2 colloid solution was prepared in the same manner as in Comparative Example 1 except that Pt as a promoter was not supported. The photodecomposition performance of water was measured by the same method as in Example 2 using 0.5 g of this catalyst. The amount of hydrogen produced at this time is shown in FIG.
[0040]
Comparative Example 5
The photolysis performance of water was measured by the same method as in Example 2 using 0.5 g of layered titanate H 2 Ti 4 O 9 . The amount of hydrogen produced at this time is shown in FIG.
[0041]
As is apparent from FIG. 3, in Comparative Example 5 using the layered titanate H 2 Ti 4 O 9 powder, water decomposition did not proceed at all, whereas titanium oxide was replaced with layered titanate H 2 Ti 4 O 9. In Example 3 and Comparative Example 4 in which the photolysis catalyst included between 9 layers was used, stable hydrogen generation was observed. In addition, in Example 3 using the photocatalyst in which Pt-supported titanium oxide was included using the titanium acyl complex according to the present invention, the water decomposition rate was about twice as fast as in Comparative Example 4 using TiO 2 colloid. .
[0042]
As can be seen from FIGS. 2 and 3, the amount of hydrogen produced in Examples 2 and 3 by the catalyst including titanium oxide using the titanium acyl complex according to the present invention is the same as that of the catalyst including titanium oxide using TiO 2 colloid. It was higher than Comparative Examples 2 and 4 and showed good photodecomposition characteristics.
[0043]
【The invention's effect】
According to the first to eighth aspects of the invention, it is possible to provide a photodecomposition catalyst in which ultrafine titanium oxide is uniformly clad between layers of a layered titanate compound at a high concentration, and provides excellent photocatalytic activity. can do.
[0044]
Further, the photocatalytic activity can be further enhanced by supporting the cocatalyst on the titanium oxide clad between the layers according to the inventions of the fifth to seventh aspects.
According to invention of Claim 9-12, by using the photolysis catalyst of the said invention, water can be photolyzed efficiently and hydrogen can be manufactured.
[Brief description of the drawings]
FIG. 1 is a graph showing the amount of titanium oxide inclusion in Example 1 and Comparative Example 1. FIG.
FIG. 2 is a graph showing the amount of hydrogen produced in Example 2 and Comparative Examples 2 and 3.
FIG. 3 is a graph showing hydrogen generation amounts in Example 3 and Comparative Examples 4 and 5.
Claims (11)
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