HWAHAK KONGHAK, Vol.34, No.3, 356-362, June, 1996
솔-젤 법으로 제조한 금속 담지 타이타니아 광촉매의 액상반응 특성
Photodegradation of Organic Pollutants in Water Using Metal-Supported TiO2 Catalysts Prepared by Sol-Gel Techniques
초록
스핀코팅법 및 침지코팅법을 이용하여 평판형 스테인레스 스틸 금속담체 위에 타이타니아 촉매를 담지시키고, 수용액상에서의 포름산 분해반응을 통해 광촉매 반응활성을 측정하였다. Tio2/금속담체 촉매를 사용하는 경우에는 반응에 의해 금속담체 표면의 산화층이 환원되어 색깔이 변하는 현상이 관찰되었다. 담지된 타이타니아 촉매의 결정구조는 소결온도 600℃까지 아나타제 상을 유지하고 있었으며, 루타일 상은 관찰되지 않았다. 그러나 소결온도가 증가함에 따라 촉매의 반응활성이 급격히 감소되었다. 이것은 소결온도 증가시 촉매의 입자 크기가 증가하고 비표면적(BET 표면적)이 감소하기 때문에 나타나는 현상이다. 촉매를 금속판의 양면에 코팅하면 한 면에만 코팅한 경우에 비해 약 2배 정도의 반응활성을 보였다. 이것은 광촉매의 활성화 과정에서 생성된 전자들이 금속담체의 반대 면으로 이동되어 소비되므로써, electron과 hole의 재결합반응이 억제되어 결과적으로 반응성이 증가된 때문이다. 촉매의 반응활성은 사용된 코팅방법에 큰 영향을 받지 않았다.
TiO2 catalysts supported on stainless steeless plates were prepared by using either a spin-coating or dip-coating method and tested for the photocatalytic degradation of formic acid in an aqueous solution. During the photodegradation reaction, the oxidized surface of the metallic support was reduced and bleached. The XRD patterns of the supported TiO2 catalysts which were fired at temperatures up to 600℃ showed that all of the TiO2 films had only an anatase structure, and the particle size increased as the firing temperature, which implies a nearly linear relationship of the activity with the BET surface area of the TiO2 catalyst. When the catalyst was coated on both side of the support plate, it appeared that total reaction rates increased as much as 2 times compared to those of the one-side-coated catalysts, even though UV light was illuminated only on one side of the catalyst plate in both cases. The activities of the catalysts were not affected by the coating methods employed.
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