JP4154483B2 - Photocatalyst carrier and method for producing the same - Google Patents
Photocatalyst carrier and method for producing the same Download PDFInfo
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- JP4154483B2 JP4154483B2 JP2003174954A JP2003174954A JP4154483B2 JP 4154483 B2 JP4154483 B2 JP 4154483B2 JP 2003174954 A JP2003174954 A JP 2003174954A JP 2003174954 A JP2003174954 A JP 2003174954A JP 4154483 B2 JP4154483 B2 JP 4154483B2
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- acid
- solid particles
- porous
- photocatalyst carrier
- siliceous solid
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- 239000011941 photocatalyst Substances 0.000 title claims description 37
- 238000004519 manufacturing process Methods 0.000 title claims description 10
- 239000002245 particle Substances 0.000 claims description 71
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 69
- ODINCKMPIJJUCX-UHFFFAOYSA-N Calcium oxide Chemical compound [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims description 47
- 239000010410 layer Substances 0.000 claims description 44
- 239000007787 solid Substances 0.000 claims description 42
- 239000002994 raw material Substances 0.000 claims description 34
- 239000000378 calcium silicate Substances 0.000 claims description 30
- 229910052918 calcium silicate Inorganic materials 0.000 claims description 30
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 claims description 30
- 239000002002 slurry Substances 0.000 claims description 29
- 239000000292 calcium oxide Substances 0.000 claims description 26
- 235000012255 calcium oxide Nutrition 0.000 claims description 26
- 239000000377 silicon dioxide Substances 0.000 claims description 25
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 25
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 24
- 238000001027 hydrothermal synthesis Methods 0.000 claims description 18
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 15
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 15
- 239000004571 lime Substances 0.000 claims description 15
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 14
- 239000003513 alkali Substances 0.000 claims description 8
- 238000010306 acid treatment Methods 0.000 claims description 7
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 4
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 claims description 4
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 4
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 4
- 239000011247 coating layer Substances 0.000 claims description 4
- XBDQKXXYIPTUBI-UHFFFAOYSA-N dimethylselenoniopropionate Natural products CCC(O)=O XBDQKXXYIPTUBI-UHFFFAOYSA-N 0.000 claims description 4
- 239000011521 glass Substances 0.000 claims description 4
- JVTAAEKCZFNVCJ-UHFFFAOYSA-N lactic acid Chemical compound CC(O)C(O)=O JVTAAEKCZFNVCJ-UHFFFAOYSA-N 0.000 claims description 4
- 150000007522 mineralic acids Chemical class 0.000 claims description 4
- 229910017604 nitric acid Inorganic materials 0.000 claims description 4
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims description 3
- 239000000920 calcium hydroxide Substances 0.000 claims description 3
- 235000011116 calcium hydroxide Nutrition 0.000 claims description 3
- 229910001861 calcium hydroxide Inorganic materials 0.000 claims description 3
- 150000007524 organic acids Chemical class 0.000 claims description 3
- OFOBLEOULBTSOW-UHFFFAOYSA-N Propanedioic acid Natural products OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 claims description 2
- 230000002378 acidificating effect Effects 0.000 claims description 2
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 2
- 150000001768 cations Chemical class 0.000 claims description 2
- 239000004310 lactic acid Substances 0.000 claims description 2
- 235000014655 lactic acid Nutrition 0.000 claims description 2
- VZCYOOQTPOCHFL-UPHRSURJSA-N maleic acid Chemical compound OC(=O)\C=C/C(O)=O VZCYOOQTPOCHFL-UPHRSURJSA-N 0.000 claims description 2
- 239000011976 maleic acid Substances 0.000 claims description 2
- 235000019260 propionic acid Nutrition 0.000 claims description 2
- IUVKMZGDUIUOCP-BTNSXGMBSA-N quinbolone Chemical compound O([C@H]1CC[C@H]2[C@H]3[C@@H]([C@]4(C=CC(=O)C=C4CC3)C)CC[C@@]21C)C1=CCCC1 IUVKMZGDUIUOCP-BTNSXGMBSA-N 0.000 claims description 2
- VZCYOOQTPOCHFL-UHFFFAOYSA-N trans-butenedioic acid Natural products OC(=O)C=CC(O)=O VZCYOOQTPOCHFL-UHFFFAOYSA-N 0.000 claims description 2
- BVKZGUZCCUSVTD-UHFFFAOYSA-N carbonic acid Chemical compound OC(O)=O BVKZGUZCCUSVTD-UHFFFAOYSA-N 0.000 claims 2
- 239000000463 material Substances 0.000 description 14
- 238000010438 heat treatment Methods 0.000 description 13
- 235000012239 silicon dioxide Nutrition 0.000 description 13
- 238000003756 stirring Methods 0.000 description 13
- 229910002026 crystalline silica Inorganic materials 0.000 description 12
- 229910004298 SiO 2 Inorganic materials 0.000 description 11
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 9
- 239000000758 substrate Substances 0.000 description 9
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 7
- 239000002253 acid Substances 0.000 description 7
- 239000011248 coating agent Substances 0.000 description 7
- 238000000576 coating method Methods 0.000 description 7
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 7
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 6
- 239000002585 base Substances 0.000 description 6
- 239000000243 solution Substances 0.000 description 6
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 5
- 238000000034 method Methods 0.000 description 5
- 238000002156 mixing Methods 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- 230000001699 photocatalysis Effects 0.000 description 5
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 4
- 239000007864 aqueous solution Substances 0.000 description 4
- 238000000354 decomposition reaction Methods 0.000 description 4
- 230000032798 delamination Effects 0.000 description 4
- 239000000741 silica gel Substances 0.000 description 4
- 229910002027 silica gel Inorganic materials 0.000 description 4
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 description 3
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- 229910001854 alkali hydroxide Inorganic materials 0.000 description 3
- 150000008044 alkali metal hydroxides Chemical class 0.000 description 3
- 150000001875 compounds Chemical class 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 150000002500 ions Chemical class 0.000 description 3
- 239000011148 porous material Substances 0.000 description 3
- -1 that is Chemical compound 0.000 description 3
- 239000005749 Copper compound Substances 0.000 description 2
- 239000011324 bead Substances 0.000 description 2
- 229910000019 calcium carbonate Inorganic materials 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 239000000969 carrier Substances 0.000 description 2
- 150000001880 copper compounds Chemical class 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 230000003301 hydrolyzing effect Effects 0.000 description 2
- 238000011068 loading method Methods 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000002344 surface layer Substances 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000004703 alkoxides Chemical class 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 125000005586 carbonic acid group Chemical group 0.000 description 1
- 239000012050 conventional carrier Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 239000010433 feldspar Substances 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 239000010881 fly ash Substances 0.000 description 1
- 239000006260 foam Substances 0.000 description 1
- 125000000524 functional group Chemical group 0.000 description 1
- 229910052736 halogen Inorganic materials 0.000 description 1
- 150000002367 halogens Chemical class 0.000 description 1
- 229910001507 metal halide Inorganic materials 0.000 description 1
- 150000005309 metal halides Chemical class 0.000 description 1
- 229910021426 porous silicon Inorganic materials 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 239000004575 stone Substances 0.000 description 1
- 125000000542 sulfonic acid group Chemical group 0.000 description 1
- 150000003609 titanium compounds Chemical class 0.000 description 1
- 239000004408 titanium dioxide Substances 0.000 description 1
- 239000011800 void material Substances 0.000 description 1
- 229910052724 xenon Inorganic materials 0.000 description 1
- FHNFHKCVQCLJFQ-UHFFFAOYSA-N xenon atom Chemical compound [Xe] FHNFHKCVQCLJFQ-UHFFFAOYSA-N 0.000 description 1
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- Catalysts (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は光触媒、例えば酸化チタンを担持して使用するのに好適な非多孔ケイ酸質固体粒子からなる担体、さらに詳しくいえば、表面が多孔質シリカ層で一体的に被覆された非多孔ケイ酸質固体粒子からなる光触媒用担体及びその製造方法に関するものである。
【０００２】
【従来の技術】
酸化チタンのような光触媒は、その機能を向上させるために、通常、多孔質基材又は表面を多孔質膜で被覆した基材に担持させて使用されている。
すなわち、これまでにシリカゲルのもつ吸着力を利用し、粒状又は粉末状のシリカゲルに二酸化チタンを担持させて水処理やガス処理に用いること（特許文献１参照）や、シリカ原料と石灰原料とを水の存在下で水熱反応させて得られるケイ酸カルシウムの硬化体に銅化合物を担持させた光触媒材料（特許文献２参照）、シラス発泡体に酸化チタンを担持させた光触媒材料（特許文献３参照）などが知られている。
【０００３】
しかしながら、シリカゲルは水に対する親和力が非常に大きく、粒子間空隙が小さいために、水中では毛細管現象によって水を吸収し、シリカゲル中に粒子間の結合力以上の不均一な歪みを生じて崩壊するという致命的な欠陥を抱えている上に、細孔が小さく、酸化チタン粒子が表層だけに吸着するにすぎないため、酸化チタンの担持率が低く、分解効率が劣るのを免れない。
【０００４】
また、ケイ酸カルシウム硬化体やシラスバルーンのような非多孔ケイ酸質固体粒子は比表面積が小さく、銅化合物や酸化チタンの吸着が十分に行われないため、分解効率の高い光触媒材料を得ることが困難である。
【０００５】
そのほか、アルコキシシランを加水分解し、焼成してシリカ被覆を表面に形成させたのち、スルホン酸基のような親水性官能基を導入した高比表面積の非晶質シリカ粒子を担体として用いることも考えられるが、このものを製造するには基材から被覆が剥離するのを防止するために、基材上へのコーティング、乾燥、焼成を複数回繰り返さなければならず、操作が煩雑である上に、アルコキシシランを用いるためコスト高になるのを避けられないので実用的ではない。
【０００６】
【特許文献１】
特開平１１−１３８０１７号公報（特許請求の範囲その他）
【特許文献２】
特開平８−２９４６２８号公報（特許請求の範囲その他）
【特許文献３】
特開２０００−８６２９２号公報（特許請求の範囲その他）
【０００７】
【発明が解決しようとする課題】
本発明は、このような事情のもとで、従来の光触媒担体における欠点を克服し、安定供給可能な原料を用い、水中での崩壊や基材と被覆層との間の剥離を起こすことのない、光触媒粒子の吸着率の高い光触媒用担体を、簡単な操作でかつ安価に提供することを目的としてなされたものである。
【０００８】
【課題を解決するための手段】
本発明者らは、光触媒用担体として適した材料を開発するために鋭意研究を重ねた結果、容易に入手し得る非多孔ケイ酸質固体粒子上に慣用の石灰原料を用い、水熱反応によりケイ酸カルシウム層を形成させ、さらに酸処理することにより、非多孔ケイ酸質固体粒子と多孔質シリカ被覆層とが一体的に結合した光触媒吸着性の高い担体が得られることを見出し、この知見に基づいて本発明をなすに至った。
【０００９】
すなわち、本発明は、非多孔ケイ酸質固体粒子と、その表面に一体的に結合した多孔質シリカ被覆層からなる光触媒用担体、及び水又はアルカリ水溶液中において、非多孔ケイ酸質固体粒子と石灰原料とを水熱反応させて、ケイ酸カルシウム層で被覆された非多孔ケイ酸質固体粒子を含むスラリーを調製し、次いでこのスラリーを必要に応じ炭酸化処理したのち、酸処理することを特徴とする多孔質シリカ層で表面が一体的に被覆された非多孔ケイ酸質固体粒子からなる光触媒用担体の製造方法を提供するものである。
【００１０】
【発明の実施の形態】
本発明の光触媒用担体は、非多孔ケイ酸質固体粒子とその上に一体的に被覆された多孔質シリカ層から構成されている。この非多孔ケイ酸質固体粒子とは、その組成中にＳｉＯ2を含む物質、例えば石英、ガラス、ケイ砂、長石、フライアッシュ、陶石、スラグ、結晶質ケイ酸などのシリカ含有物質の非多孔質固体粒子である。
【００１１】
本発明においては、これらの固体粒子を単独で用いてもよいし、また２種以上を組み合わせて用いてもよい。これらの固体粒子としては平均粒子径２０〜２０００μｍの範囲をもつものが好ましい。
【００１２】
また、この非多孔ケイ酸質固体粒子表面を被覆する多孔質シリカ層は、本質的にシリカから構成された孔径１〜１００μｍのミクロ細孔からマクロ細孔に至る細孔を有する多孔質体であり、ＢＥＴ比表面積５〜１００ｍ2／ｇ、好ましくは５０ｍ2／ｇをもつ層として層厚１〜１０μｍ、好ましくは３〜８μｍで非多孔ケイ酸質固体粒子の表面を被覆している。
【００１３】
このような構成をもつ本発明の光触媒用担体は、基材が非多孔ケイ酸質固体粒子であり、その被覆が多孔質シリカ層であるため、両者が一体化しており、基材と被覆とが剥離しにくいという特徴を有している。
【００１４】
この光触媒用担体を製造するには、先ず基材となる非多孔ケイ酸質固体粒子と石灰原料とを、水又はアルカリ水溶液に懸濁し、水熱反応させて、非多孔ケイ酸質固体粒子表面にケイ酸カルシウム層を形成させる。
【００１５】
この際の石灰原料としては、生石灰すなわち酸化カルシウム又は消石灰すなわち水酸化カルシウムが用いられるが、これは単独で用いても両者を混合して用いてもよい。
【００１６】
この方法において、非多孔ケイ酸質固体粒子と石灰原料とは、それぞれの主成分であるＳｉＯ2とＣａＯに基づき、ＳｉＯ2とＣａＯとのモル比が１０００：１ないし１０：３、好ましくは１００：１ないし１０：１になる割合で用いられる。これよりもＣａＯの割合が少ないとケイ酸カルシウム層の形成が不十分で、光触媒の担持率が低くなるし、またこれよりもＣａＯの割合が多くなるとケイ酸カルシウムの層厚が大きくなりすぎ光触媒による層厚当りの分解率が低下する。
【００１７】
水熱反応を行うには、これらの非多孔ケイ酸質固体粒子と石灰原料とを水又はアルカリ水溶液中に懸濁して水性スラリーを調製する。このアルカリ水溶液とは、アルカリ性化合物を水に溶解して得られるアルカリ性を示す水溶液である。このアルカリ性化合物としては水酸化アルカリ、例えば水酸化リチウム、水酸化ナトリウム、水酸化カリウムなどが好ましいが、それ以外のアルカリ性化合物例えば水溶性アルカリ金属塩を用いることもできる。これらは単独で用いてもよいし、２種以上混合して用いてもよい。
【００１８】
この場合のアルカリ濃度としては、０．０１〜１．０モル濃度が好ましい。この濃度が０．０１モル未満では、生成するケイ酸カルシウム層の結晶形態を変化させたり、水熱反応を促進させるアルカリ添加効果が十分に発揮されない。また、１．０モルよりも高くしても、アルカリ添加効果の向上はそれほどみられず、むしろ好ましくない作用が発生する。
【００１９】
一方、シリカ原料と石灰原料を含む水又は水酸化アルカリ水溶液スラリーの濃度については特に制限はないが、水熱反応性及び容積効率などを考慮すると、非多孔ケイ酸質固体粒子と石灰原料との合計量に対し、水又は水酸化アルカリ水溶液を２〜２０倍質量の割合で用いるのが有利である。
【００２０】
本発明における水熱反応は、例えばオートクレーブを用いて、１００〜２５０℃の範囲の温度で行われる。この水熱反応は自生圧力下で進行するが、必要に応じ適当に加圧して反応を行ってもよい。また、反応中は特に撹拌を行う必要はないが、反応速度を促進させるために、所望に応じて撹拌を行うこともできる。
【００２１】
水熱反応温度が１００℃未満では反応速度が遅すぎて長時間を要し実用的ではないし、また２５０℃を超えると自生圧力が高くなりすぎ、装置面などにおいて経済的に不利となる。反応時間は、スラリー濃度、原料の種類や粒度、反応温度などに左右され、一概に定めることはできないが、通常は０．５〜２０時間程度で十分である。
【００２２】
このようにして調製されたケイ酸カルシウム層で被覆された非多孔ケイ酸質固体粒子を含むスラリーは、次に酸処理される。この酸処理は、塩酸、硫酸、硝酸、リン酸、炭酸のような無機酸、又は酢酸、プロピオン酸、マレイン酸、乳酸、酸性陽イオン交換剤のような有機酸を添加することによって行われる。
【００２３】
この場合、塩酸、硝酸などの無機酸は、電離度が大きく、急激にｐＨを降下させる。電離度の大きい塩酸、硝酸などで非多孔ケイ酸質固体粒子表面のケイ酸カルシウム層を処理する場合は、ｐＨが急激に降下しないように希釈した酸を徐々に添加すると、ケイ酸カルシウムの形態を変化させることなく、酸化カルシウムが除去され、非多孔ケイ酸質固体粒子表面に多孔質シリカ層が形成される。なお、ケイ酸カルシウム層の結晶性に応じては、ケイ酸カルシウムスラリーを室温〜１００℃の範囲で加熱することによって、より効率的に酸化カルシウムを除去することができる。
【００２４】
これに対し、電離度が小さい酢酸、炭酸（スラリーに炭酸ガスを吹き込むと炭酸となる）などの場合は、高濃度の酸で直接ケイ酸カルシウムを処理しても、酸が急激にイオンに解離せず、イオンの消費に伴って、徐々にイオンに解離するため、酸化カルシウムの除去も徐々に進行し、ケイ酸カルシウムの形態が維持された多孔質シリカ層となる。
【００２５】
また、非多孔ケイ酸質固体粒子をケイ酸カルシウム層で被覆したケイ酸カルシウムスラリーを室温〜１００℃の範囲で加熱すると電離度が大きくなり、酸化カルシウムの除去が促進される。なお、炭酸で処理したケイ酸カルシウムは、スラリー中に多孔質シリカと水に難溶性の炭酸カルシウムが生成するため、炭酸カルシウムを塩酸などで溶解除去する必要がある。
【００２６】
この酸処理に必要な時間は、非多孔ケイ酸質固体粒子表面に形成されるケイ酸カルシウム層の厚さ、使用する酸の種類、濃度、処理条件などにより左右されるが、通常１〜１２０分間の範囲である。
【００２７】
このようにして調製した多孔質シリカ層で被覆された非多孔ケイ酸質固体粒子をふくむスラリーは、次に水で洗浄したのち１００〜１６０℃において乾燥すれば、光触媒用担体を得ることができる。
【００２８】
本発明においては、非多孔ケイ酸質固体粒子と石灰原料との使用割合（モル比 ＣａＯ／ＳｉＯ2）や水熱反応条件を選ぶことにより、非多孔ケイ酸質固体粒子表面に形成される多孔質シリカ層の厚さを自由に制御することができる。
また、非多孔ケイ酸質固体粒子、石灰原料及びアルカリ水溶液を選択することにより、多孔質シリカ層の形態や比表面積を制御することができる。
【００２９】
本発明の光触媒用担体は、例えば適当な溶剤中に無機チタン化合物を溶解して調製した溶液を含浸させ、乾燥後、加熱焼成することにより、平均層厚０．５〜１．５μｍの酸化チタン層を形成させることにより、光触媒材料とすることができる。
【００３０】
このようにして得られる光触媒材料は、種々の光源、例えば太陽光、蛍光灯、白熱灯、ブラックライト、紫外線ランプ、キセノンランプ、ハロゲンランプ、メタルハライドランプなどからの放射線を照射することにより、空気中の悪臭源、有害物質を効率よく分解除去することができる。
【００３１】
【実施例】
次に、本発明を実施例によりさらに詳細に説明するが、本発明はこれらの例によってなんら限定されるものではない。
なお、本発明の光触媒担体の性能は、以下に示す方法に従って評価した。
【００３２】
（１）光触媒担体の膜厚
走査型電子顕微鏡（ＳＥＭ）を用いて測定した。
【００３３】
（２）ＢＥＴ比表面積
ＢＥＴ比表面積測定装置を用い、２５０℃で十分に加熱脱気した試料について、窒素ガスを吸着させる多点法による比表面積を求めた。
【００３４】
（３）加熱処理試料のＢＥＴ比表面積
室温から５００℃まで１０℃／ｍｉｎで昇温して３０分間保持した後、３００℃まで電気炉中で放冷したものを取り出し、（２）の方法で比表面積を求めた。
【００３５】
（４）加熱処理試料のＳＥＭによる基材からの剥離の判定
室温から５００℃まで１０℃／ｍｉｎで昇温して３０分間保持した後、３００℃まで電気炉中で放冷したものを取り出し、ＳＥＭを用いて基材からの剥離の判定を行った。
【００３６】
実施例１
粒子径７５〜１２５μｍの結晶質シリカ粒子と、生石灰原料をＣａＯ／ＳｉＯ2モル比が１／１００になるように混合し、原料全量に対して、質量比で５倍の水を加えてオートクレーブの中に入れ、撹拌しながら１８０℃で４時間水熱反応を行い、結晶質シリカ粒子をケイ酸カルシウム層で被覆したケイ酸カルシウムスラリーを得た。このスラリーを７０℃に加熱し、濃度８０質量％の酢酸を添加し、１０分間撹拌しながら保持した後、洗浄濾過して１２０℃で乾燥処理することにより、光触媒用担体を得た。
この担体の層厚は１μｍ、ＢＥＴ比表面積は５．７ｍ2／ｇ、加熱処理後のＢＥＴ比表面積は４．８ｍ2／ｇであり、加熱処理後の層の基材からの層の剥離は認められなかった。
【００３７】
実施例２
粒子径が７５〜１２５μｍの結晶質シリカ粒子と、生石灰原料をＣａＯ／ＳｉＯ2モル比が１／１０になるように混合し、原料全量に対して、質量比で５倍の水を加えてオートクレーブの中に入れ、撹拌しながら１８０℃で４時間水熱反応を行い、結晶質シリカ粒子をケイ酸カルシウム層で被覆したケイ酸カルシウムスラリーを得た。このスラリーを７０℃に加熱し、濃度８０質量％の酢酸を添加し、１０分間撹拌しながら保持した後、洗浄濾過して１２０℃で乾燥処理することにより、光触媒用担体を得た。
この担体の層厚は５μｍ、ＢＥＴ比表面積は３５．４ｍ2／ｇ、加熱処理後のＢＥＴ比表面積は３２．５ｍ2／ｇであり、加熱処理後の層の基材からの層の剥離は認められなかった。
【００３８】
実施例３
粒子径が７５〜１２５μｍの結晶質シリカ粒子と、生石灰原料をＣａＯ／ＳｉＯ2モル比が１／１０になるように混合し、原料全量に対して、質量比で５倍の０．０５モル濃度の水酸化ナトリウム水溶液を加えてオートクレーブの中に入れ、撹拌しながら１８０℃で４時間水熱反応を行い、結晶質シリカ粒子をケイ酸カルシウム層で被覆したケイ酸カルシウムスラリーを得た。このスラリーを７０℃に加熱し、濃度８０質量％の酢酸を添加し、１０分間撹拌した後、洗浄濾過して１２０℃で乾燥処理することにより、光触媒用担体を得た。
この担体の層厚は８μｍ、ＢＥＴ比表面積は８５．０ｍ2／ｇ、加熱処理後のＢＥＴ比表面積は７３．２ｍ2／ｇであり、加熱処理後の基材からの層の剥離は認められなかった。
【００３９】
実施例４
粒子径が２０〜７５μｍの結晶質シリカ粒子と、生石灰原料をＣａＯ／ＳｉＯ2モル比が３／１００になるように混合し、原料全量に対して、質量比で５倍の水を加えてオートクレーブの中に入れ、撹拌しながら１８０℃で４時間水熱反応を行い、ケイ酸カルシウム層で被覆した結晶質シリカ粒子のスラリーを得た。このスラリーを７０℃に加熱し、濃度８０質量％の酢酸を添加し、１０分間撹拌しながら保持した後、洗浄濾過して１２０℃で乾燥処理することにより、光触媒用担体を得た。
この担体の層厚は３μｍ、ＢＥＴ比表面積は２９．２ｍ2／ｇ、加熱処理後のＢＥＴ比表面積は２７．７ｍ2／ｇであり、加熱処理後の基材からの層の剥離は認められなかった。
【００４０】
実施例５
粒子径が７５〜１２５μｍの結晶質シリカ粒子と、生石灰原料をＣａＯ／ＳｉＯ2モル比が１／１０になるように混合し、原料全量に対して、質量比で５倍の水を加えてオートクレーブの中に入れ、撹拌しながら１８０℃で４時間水熱反応を行い、ケイ酸カルシウム層で被覆した結晶質シリカ粒子のスラリーを得た。このスラリーに、二酸化炭素ガスをオートクレーブの内圧が２ｋｇ／ｃｍ2になるように調整して２時間吹き込んだ後、２モル濃度塩酸で処理し、洗浄濾過して１２０℃で乾燥処理することにより、光触媒用担体を得た。
この担体の層厚は５μｍ、ＢＥＴ比表面積は３２．７ｍ2／ｇ、加熱処理後のＢＥＴ比表面積は２７．９ｍ2／ｇであり、加熱処理後の基材からの層の剥離は認められなかった。
【００４１】
実施例６
粒子径が１０５〜１２５μｍのガラスビーズと、生石灰原料をＣａＯ／ＳｉＯ2モル比が３／１００になるように混合し、原料全量に対して、質量比で５倍の水を加えてオートクレーブの中に入れ、撹拌しながら１８０℃で４時間水熱反応を行い、シリカ原料粒子をケイ酸カルシウム層で被覆したガラスビーズ粒子のスラリーを得た。このスラリーを７０℃に加熱し、濃度８０重量％の酢酸を添加し、１０分間撹拌しながら保持した後、洗浄濾過して１２０℃で乾燥処理することにより、光触媒用担体を得た。
この担体の層厚は３μｍで、ＢＥＴ比表面積は３９．４ｍ2／ｇ、加熱処理後のＢＥＴ比表面積は２８．８ｍ2／ｇであり、加熱処理後の基材からの層の剥離は認められなかった。
【００４２】
実施例７
粒子径が７５〜１２５μｍの結晶質シリカ粒子と、生石灰原料をＣａＯ／ＳｉＯ2モル比が１／１０になるように混合し、原料全量に対して、質量比で５倍の水を加えてオートクレーブの中に入れ、撹拌しながら１８０℃で４時間水熱反応を行い、ケイ酸カルシウム層で被覆した結晶質シリカ粒子のスラリーを得た。このスラリーを０．２モル濃度の塩酸水溶液を用い、室温においてｐＨ３．５で１０分間保持し、さらにｐＨ１．５に１０分間保持した後、洗浄濾過して１２０℃で乾燥処理することにより、光触媒用担体を得た。
この担体の層厚は５μｍ、ＢＥＴ比表面積は４２．７ｍ2／ｇ、加熱処理後のＢＥＴ比表面積は４０．９ｍ2／ｇであり、加熱処理後の基材からの層の剥離は認められなかった。
【００４３】
【発明の効果】
本発明の光触媒用担体は以下に示す長所を有している。
（１）安定供給可能な非多孔ケイ酸質固体粒子と石灰原料から短時間で簡単に、しかも安価に製造することができる。
（２）従来の担体は粒子間空隙が小さいために表層のみの吸着で、水に入れると毛細管現象によって水を吸収して崩壊するが、本発明の担体は、ミクロ孔とマクロ孔から構成されており、水に入れても崩壊せず、層厚も分解効率を考慮して適時に制御できる。
（３）アルコキシドを加水分解してシリカ被覆を基材表面に形成させる方法では、十分な被覆の厚さは得られず、被覆を厚くしようとすると基材から被覆が剥離するが、本発明の担体は、非多孔ケイ酸質固体粒子が基材となっているため、多孔質シリカ層と非多孔ケイ酸質固体粒子の基材とが一体的に結合しており、基材から多孔質シリカ層が剥離することはない。[0001]
BACKGROUND OF THE INVENTION
The present invention is a photocatalyst, such as carriers consisting of suitable non-porous siliceous solid particles for use titanium oxide by supporting, more particularly, non-porous silicon surface is integrally coated with a porous silica layer The present invention relates to a photocatalyst carrier comprising acid solid particles and a method for producing the same.
[0002]
[Prior art]
In order to improve the function, a photocatalyst such as titanium oxide is usually used by being supported on a porous substrate or a substrate whose surface is covered with a porous film.
That is, by utilizing the adsorption power of silica gel so far, titanium dioxide is supported on granular or powdered silica gel and used for water treatment or gas treatment (see Patent Document 1), silica raw material and lime raw material A photocatalytic material in which a copper compound is supported on a hardened calcium silicate obtained by hydrothermal reaction in the presence of water (see Patent Document 2), and a photocatalytic material in which titanium oxide is supported on a shirasu foam (Patent Document 3) For example).
[0003]
However, since silica gel has a very high affinity for water and the inter-particle voids are small, it absorbs water by capillarity in water, resulting in non-uniform distortion in the silica gel that exceeds the binding force between the particles. In addition to having fatal defects, the pores are small and the titanium oxide particles are only adsorbed only on the surface layer, so that the titanium oxide loading rate is low and the decomposition efficiency is unavoidable.
[0004]
In addition, non-porous siliceous solid particles such as hardened calcium silicate and Shirasu balloons have a small specific surface area and do not sufficiently adsorb copper compounds and titanium oxide, so that a photocatalytic material with high decomposition efficiency can be obtained. Is difficult.
[0005]
In addition, after hydrolyzing alkoxysilane and baking to form a silica coating on the surface, amorphous silica particles having a high specific surface area into which a hydrophilic functional group such as a sulfonic acid group is introduced may be used as a carrier. Although it is conceivable, in order to prevent the coating from peeling off from the base material, it is necessary to repeat coating, drying and firing on the base material a plurality of times, and the operation is complicated. In addition, since the use of alkoxysilane is unavoidable, it is not practical.
[0006]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-138017 (claims and others)
[Patent Document 2]
JP-A-8-294628 (Claims and others)
[Patent Document 3]
JP 2000-86292 A (Claims and others)
[0007]
[Problems to be solved by the invention]
Under such circumstances, the present invention overcomes the drawbacks of conventional photocatalyst carriers, uses raw materials that can be stably supplied, and causes disintegration in water and separation between the substrate and the coating layer. The present invention has been made for the purpose of providing a photocatalyst carrier having a high adsorption rate of photocatalyst particles with a simple operation and at a low cost.
[0008]
[Means for Solving the Problems]
As a result of intensive studies to develop a material suitable as a support for a photocatalyst, the present inventors have used a conventional lime raw material on readily available non-porous siliceous solid particles, and hydrothermal reaction. to form a calcium silicate layer, further by acid treatment, non-porous siliceous solid particles and the porous silica coating layer found that the resulting high carrier photocatalytic absorptive coupled integrally, this finding The present invention has been made based on the above.
[0009]
That is, the present invention relates to a nonporous siliceous solid particle, a support for a photocatalyst comprising a porous silica coating layer integrally bonded to the surface thereof , and a nonporous siliceous solid particle in water or an alkaline aqueous solution. A slurry containing non-porous siliceous solid particles coated with a calcium silicate layer is prepared by hydrothermal reaction with a lime raw material, and then the slurry is carbonized as necessary, and then acid-treated. The present invention provides a method for producing a photocatalyst carrier comprising nonporous siliceous solid particles whose surfaces are integrally coated with a porous silica layer.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The photocatalyst carrier of the present invention is composed of non-porous siliceous solid particles and a porous silica layer integrally coated thereon. And the non-porous siliceous solid particles, substances containing SiO 2 in the composition thereof, for example, quartz, glass, silica sand, feldspar, fly ash, pottery stone, slag, silica-containing materials such as sintered crystalline silicate Non-porous solid particles.
[0011]
In the present invention, these solid particles may be used alone or in combination of two or more. As these solid particles, those having an average particle diameter of 20 to 2000 μm are preferable.
[0012]
Further, the porous silica layer covering the surface of the non-porous siliceous solid particles is a porous body having pores ranging from micropores having a pore diameter of 1 to 100 μm essentially composed of silica to macropores. Yes, as a layer having a BET specific surface area of 5 to 100 m 2 / g, preferably 50 m 2 / g, the surface of the nonporous siliceous solid particles is coated with a layer thickness of 1 to 10 μm, preferably 3 to 8 μm.
[0013]
In the photocatalyst carrier of the present invention having such a configuration, since the base material is non-porous siliceous solid particles and the coating is a porous silica layer, both are integrated, and the base material and the coating Is difficult to peel off.
[0014]
In order to produce this photocatalyst carrier, first, the non-porous siliceous solid particles and the lime raw material that are the base material are suspended in water or an aqueous alkali solution and hydrothermally reacted to obtain a surface of the non-porous siliceous solid particles. To form a calcium silicate layer.
[0015]
As the lime raw material in this case, quick lime, that is, calcium oxide, or slaked lime, that is, calcium hydroxide, is used, but these may be used alone or in combination.
[0016]
In this method, the non-porous siliceous solid particles and the lime raw material are based on SiO 2 and CaO as main components, respectively, and the molar ratio of SiO 2 and CaO is 1000: 1 to 10: 3, preferably 100. 1 to 10: 1. If the CaO ratio is less than this, the formation of the calcium silicate layer is insufficient, and the photocatalyst loading rate is low, and if the CaO ratio is higher than this, the calcium silicate layer thickness becomes too large and the photocatalyst becomes too thick. Decomposition rate per layer thickness due to decrease.
[0017]
In order to carry out the hydrothermal reaction, these non-porous siliceous solid particles and lime raw material are suspended in water or an aqueous alkali solution to prepare an aqueous slurry. This alkaline aqueous solution is an aqueous solution showing alkalinity obtained by dissolving an alkaline compound in water. The alkaline compound is preferably an alkali hydroxide such as lithium hydroxide, sodium hydroxide or potassium hydroxide, but other alkaline compounds such as water-soluble alkali metal salts can also be used. These may be used alone or in combination of two or more.
[0018]
In this case, the alkali concentration is preferably 0.01 to 1.0 molar. If this concentration is less than 0.01 mol, the effect of alkali addition that changes the crystal form of the generated calcium silicate layer or promotes the hydrothermal reaction is not sufficiently exhibited. Moreover, even if it is made higher than 1.0 mol, the alkali addition effect is not so much improved, but an undesirable action occurs.
[0019]
On the other hand, there is no particular limitation on the concentration of water or alkali hydroxide aqueous slurry containing silica raw material and lime raw material, but considering hydrothermal reactivity and volumetric efficiency, the nonporous siliceous solid particles and lime raw material It is advantageous to use water or an aqueous alkali hydroxide solution in a proportion of 2 to 20 times the mass of the total amount.
[0020]
The hydrothermal reaction in this invention is performed at the temperature of the range of 100-250 degreeC, for example using an autoclave. This hydrothermal reaction proceeds under an autogenous pressure, but the reaction may be carried out by appropriately applying pressure as necessary. Further, stirring is not particularly required during the reaction, but stirring may be performed as desired in order to accelerate the reaction rate.
[0021]
If the hydrothermal reaction temperature is less than 100 ° C., the reaction rate is too slow and takes a long time, which is not practical, and if it exceeds 250 ° C., the self-generated pressure becomes too high, which is economically disadvantageous in terms of equipment. The reaction time depends on the slurry concentration, the type and particle size of the raw material, the reaction temperature, and the like, and cannot be determined in general, but usually about 0.5 to 20 hours is sufficient.
[0022]
The slurry containing non-porous siliceous solid particles coated with the calcium silicate layer thus prepared is then acid treated. This acid treatment is carried out by adding an inorganic acid such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid or carbonic acid, or an organic acid such as acetic acid, propionic acid, maleic acid, lactic acid or acidic cation exchanger.
[0023]
In this case, inorganic acids such as hydrochloric acid and nitric acid have a high degree of ionization, and the pH is rapidly lowered. When treating the calcium silicate layer on the surface of non-porous siliceous solid particles with hydrochloric acid, nitric acid, etc. with a high degree of ionization, gradually add diluted acid so that the pH does not drop rapidly. without changing the calcium oxide is removed, a porous silica layer is formed on the nonporous siliceous solid particle surface. Depending on the crystallinity of the calcium silicate layer, calcium oxide can be more efficiently removed by heating the calcium silicate slurry in the range of room temperature to 100 ° C.
[0024]
On the other hand, in the case of acetic acid or carbonic acid with a low ionization degree (carbonic acid is generated when carbon dioxide is blown into the slurry), the acid is rapidly dissolved into ions even if calcium silicate is directly treated with a high concentration of acid. Since it is dissociated gradually into ions as the ions are consumed, the removal of calcium oxide also proceeds gradually, resulting in a porous silica layer in which the form of calcium silicate is maintained.
[0025]
Moreover, when the calcium silicate slurry which coat | covered the nonporous siliceous solid particle | grains with the calcium silicate layer is heated in the range of room temperature-100 degreeC, an ionization degree will become large and removal of a calcium oxide will be accelerated | stimulated. In addition, since calcium silicate treated with carbonic acid forms poorly soluble calcium carbonate in porous silica and water in the slurry, it is necessary to dissolve and remove the calcium carbonate with hydrochloric acid or the like.
[0026]
The time required for the acid treatment depends on the thickness of the calcium silicate layer formed on the surface of the non-porous siliceous solid particles, the type of acid used, the concentration, the treatment conditions, etc., but usually 1 to 120. The range of minutes.
[0027]
The slurry containing the non-porous siliceous solid particles coated with the porous silica layer thus prepared can be washed with water and then dried at 100 to 160 ° C. to obtain a photocatalyst support. .
[0028]
In the present invention, by selecting the use ratio (molar ratio CaO / SiO 2 ) of the nonporous siliceous solid particles and the lime raw material and the hydrothermal reaction conditions, the porous formed on the surface of the nonporous siliceous solid particles. The thickness of the porous silica layer can be freely controlled.
Moreover, the form and specific surface area of a porous silica layer are controllable by selecting a non-porous siliceous solid particle, a lime raw material, and aqueous alkali solution.
[0029]
The photocatalyst carrier of the present invention is, for example, impregnated with a solution prepared by dissolving an inorganic titanium compound in a suitable solvent, dried and then heated and fired to obtain an average layer thickness of 0.5 to 1.5 μm of titanium oxide. A photocatalytic material can be obtained by forming a layer.
[0030]
The photocatalyst material thus obtained is irradiated with radiation from various light sources such as sunlight, fluorescent lamp, incandescent lamp, black light, ultraviolet lamp, xenon lamp, halogen lamp, metal halide lamp, etc. It can efficiently decompose and remove odor sources and harmful substances.
[0031]
【Example】
EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these examples.
The performance of the photocatalyst carrier of the present invention was evaluated according to the method shown below.
[0032]
(1) Film thickness of photocatalyst carrier It measured using the scanning electron microscope (SEM).
[0033]
(2) BET specific surface area Using a BET specific surface area measuring apparatus, a specific surface area was determined by a multipoint method in which nitrogen gas was adsorbed on a sample sufficiently heated and degassed at 250 ° C.
[0034]
(3) BET specific surface area of heat-treated sample After raising the temperature from room temperature to 500 ° C. at 10 ° C./min and holding it for 30 minutes, take out the one that was allowed to cool in an electric furnace to 300 ° C., and use the method of (2) The specific surface area was determined.
[0035]
(4) Judgment of peeling from base material by SEM of heat-treated sample After raising the temperature from room temperature to 500 ° C. at 10 ° C./min and holding for 30 minutes, the one cooled in an electric furnace to 300 ° C. was taken out, Determination of peeling from the base material was performed using SEM.
[0036]
Example 1
Crystalline silica particles having a particle diameter of 75 to 125 μm and quick lime raw material are mixed so that the CaO / SiO 2 molar ratio is 1/100, and water is added 5 times by mass with respect to the total amount of the raw material. The mixture was put in and subjected to hydrothermal reaction at 180 ° C. for 4 hours with stirring to obtain a calcium silicate slurry in which crystalline silica particles were coated with a calcium silicate layer. This slurry was heated to 70 ° C., 80% by weight of acetic acid was added, and the mixture was held for 10 minutes with stirring, washed and filtered, and dried at 120 ° C. to obtain a photocatalyst carrier.
This carrier has a layer thickness of 1 μm, a BET specific surface area of 5.7 m 2 / g, and a BET specific surface area after heat treatment of 4.8 m 2 / g. I was not able to admit.
[0037]
Example 2
The autoclave is prepared by mixing crystalline silica particles having a particle diameter of 75 to 125 μm and quick lime raw material so that the CaO / SiO 2 molar ratio becomes 1/10, and adding 5 times the mass ratio of water to the total amount of the raw material. Then, hydrothermal reaction was carried out at 180 ° C. for 4 hours with stirring to obtain a calcium silicate slurry in which crystalline silica particles were coated with a calcium silicate layer. This slurry was heated to 70 ° C., 80% by weight of acetic acid was added, and the mixture was held for 10 minutes with stirring, washed and filtered, and dried at 120 ° C. to obtain a photocatalyst carrier.
The carrier has a layer thickness of 5 μm, a BET specific surface area of 35.4 m 2 / g, and a BET specific surface area after heat treatment of 32.5 m 2 / g. I was not able to admit.
[0038]
Example 3
Crystalline silica particles having a particle diameter of 75 to 125 μm and quick lime raw material are mixed so that the CaO / SiO 2 molar ratio is 1/10, and the molar ratio of 0.05 molar is 5 times the total amount of the raw material. An aqueous sodium hydroxide solution was added and placed in an autoclave, and a hydrothermal reaction was performed at 180 ° C. for 4 hours with stirring to obtain a calcium silicate slurry in which crystalline silica particles were coated with a calcium silicate layer. This slurry was heated to 70 ° C., 80% by mass of acetic acid was added, stirred for 10 minutes, washed, filtered and dried at 120 ° C. to obtain a photocatalyst support.
The carrier has a layer thickness of 8 μm, a BET specific surface area of 85.0 m 2 / g, a BET specific surface area after heat treatment of 73.2 m 2 / g, and peeling of the layer from the substrate after heat treatment is observed. There wasn't.
[0039]
Example 4
The autoclave is prepared by mixing crystalline silica particles having a particle size of 20 to 75 μm and quicklime raw material so that the CaO / SiO 2 molar ratio is 3/100, and adding 5 times the mass ratio of water to the total amount of the raw material. And a hydrothermal reaction at 180 ° C. for 4 hours with stirring to obtain a slurry of crystalline silica particles coated with a calcium silicate layer. This slurry was heated to 70 ° C., 80% by weight of acetic acid was added, and the mixture was held for 10 minutes with stirring, washed and filtered, and dried at 120 ° C. to obtain a photocatalyst carrier.
The thickness of the carrier is 3 [mu] m, BET specific surface area of 29.2m 2 / g, BET specific surface area after heat treatment was 27.7m 2 / g, delamination is observed from the substrate after the heat treatment There wasn't.
[0040]
Example 5
The autoclave is prepared by mixing crystalline silica particles having a particle diameter of 75 to 125 μm and quick lime raw material so that the CaO / SiO 2 molar ratio becomes 1/10, and adding 5 times the mass ratio of water to the total amount of the raw material. And a hydrothermal reaction at 180 ° C. for 4 hours with stirring to obtain a slurry of crystalline silica particles coated with a calcium silicate layer. Carbon dioxide gas was adjusted to the slurry so that the internal pressure of the autoclave was adjusted to 2 kg / cm 2 and then blown for 2 hours, then treated with 2 molar hydrochloric acid, washed, filtered and dried at 120 ° C. A photocatalyst support was obtained.
The thickness of the support is 5 [mu] m, BET specific surface area of 32.7m 2 / g, BET specific surface area after heat treatment was 27.9 m 2 / g, delamination is observed from the substrate after the heat treatment There wasn't.
[0041]
Example 6
Mixing glass beads with a particle size of 105 to 125 μm and quicklime raw material so that the CaO / SiO 2 molar ratio is 3/100, and adding 5 times the mass ratio of water to the total amount of raw material in the autoclave And a hydrothermal reaction at 180 ° C. for 4 hours with stirring to obtain a slurry of glass bead particles in which silica raw material particles were coated with a calcium silicate layer. This slurry was heated to 70 ° C., 80% by weight of acetic acid was added and held for 10 minutes with stirring, then washed and filtered and dried at 120 ° C. to obtain a photocatalyst carrier.
This thickness of the support is 3 [mu] m, BET specific surface area of 39.4m 2 / g, BET specific surface area after heat treatment was 28.8 m 2 / g, observed delamination from the substrate after the heat treatment I couldn't.
[0042]
Example 7
The autoclave is prepared by mixing crystalline silica particles having a particle diameter of 75 to 125 μm and quick lime raw material so that the CaO / SiO 2 molar ratio becomes 1/10, and adding 5 times the mass ratio of water to the total amount of the raw material. And a hydrothermal reaction at 180 ° C. for 4 hours with stirring to obtain a slurry of crystalline silica particles coated with a calcium silicate layer. This slurry was maintained at pH 3.5 at room temperature for 10 minutes using a 0.2 molar hydrochloric acid aqueous solution, further maintained at pH 1.5 for 10 minutes, washed, filtered, and dried at 120 ° C. to obtain a photocatalyst. A carrier was obtained.
The thickness of the support is 5 [mu] m, BET specific surface area of 42.7m 2 / g, BET specific surface area after heat treatment was 40.9m 2 / g, delamination is observed from the substrate after the heat treatment There wasn't.
[0043]
【The invention's effect】
The photocatalyst carrier of the present invention has the following advantages.
(1) It can be produced easily and inexpensively in a short time from non-porous siliceous solid particles and lime raw material that can be stably supplied.
(2) Since the conventional carrier has a small interparticle void, it is adsorbed only on the surface layer, and when it is put into water, it absorbs water and collapses by capillary action. However, the carrier of the present invention is composed of micropores and macropores. It does not disintegrate even when placed in water, and the layer thickness can be controlled in a timely manner in consideration of decomposition efficiency.
(3) In the method of hydrolyzing alkoxide to form a silica coating on the surface of the substrate, a sufficient coating thickness cannot be obtained. Since the support is made of non-porous silicate solid particles, the porous silica layer and the non-porous silicate solid particles are integrally bonded to each other. The layers do not delaminate.
Claims (9)
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| CN111613455B (en) * | 2020-06-01 | 2021-06-25 | 兰州理工大学 | Reinforced NiCo2O4Method for material specific capacitance of super capacitor material |
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| CN112705185A (en) * | 2020-12-29 | 2021-04-27 | 四川建筑职业技术学院 | Preparation method of quartz sand/titanium dioxide composite catalyst |
| CN113398980B (en) * | 2021-06-15 | 2022-07-15 | 东北大学 | Coal ash based X zeolite-TiO2Preparation method of composite photocatalyst |
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