Journal of the Korean Industrial and Engineering Chemistry, Vol.12, No.6, 614-619, October, 2001
담지된 광촉매를 이용한 질소산화물 광분해 연구
Photocatalytic Decomposition of Nitric Oxide Over Supported Photocatalyst
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초록
여러 종류의 담체에 TiO2가 담지된 광촉매를 이용하여 일산화질소(NO) 분해 연구를 진행하였다. NO 광분해 반응은 UV 조사 하에서 유동층 반응기를 이용하여 상온에서 행하였다. 함침법과 졸-겔법에 의하여 제조된 광촉매는 X-선 회절분석(X-ray diffraction, XRD), 주사 전자 현미경(scanning electron spectroscopy, SEM) 및 BET 표면적으로 특성화하였다. 실리카, 알루미나, Y-제올라이트, ZSM-5에 TiO2를 담지시킨 촉매 중에서 알루미나에 담지한 촉매가 가장 우수한 NO 광분해 활성을 보였다. 최적의 촉매인 알루미나에 10 wt%의 TiO2를 담지시키고 700 ℃에서 소성시킨 TiO2(10)/Al2O3-700 ℃ 촉매는 1h 후에 50%의 NO 분해율을 보여 27%의 NO 분해율을 보이는 TiO2 (Degussa, P-25) 보다 2배 이상 우수한 NO 광분해 활성을 보였다. 또한 최적 촉매는 NO 분해 반응 동안 촉매 표면 위에 침적되는 질소염의 양이 P-25 보다 적어 반응시간에 따른 촉매의 안정성도 우수하였다. 그러나 최적의 촉매인 TiO2(10)/Al2O3와 조성이 동일하고 졸-겔법에 의하여 제조된 TiO2-Al2O3 촉매의 NO 분해능은 10% 정도로 최적 촉매와 비교하여 상당히 낮은 활성을 보였다.
Photocatalytic decomposition of nitric oxide (NO) over TiO2 photocatalyst supported on various carriers was studied in a fluidized-bed photocatalytic reaction system containing ultra-violet (UV) irradiation at room temperature. Various supported photocatalysts, prepared by impregnation and sol-gel methods, were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and BET surface area. Among TiO2 photocatalysts supported on silica, alumina, Y-zeolite and ZSM-5, the alumina supported photocatalyst showed the best photocatalytic NO decomposition activity. The optimal catalyst was prepared by impregnation of 10 wt% TiO2 on alumina and calcined at 700 ℃ (TiO2(10)/Al2O3-700C) showed 50% NO decomposition during 1 h period. This was 2 times higher than that of the commercial TiO2 (Degussa, P-25), which showed only 27% NO decomposition during 1 h period. The optimal catalyst was more stable than P-25 because less amount of nitrogen salt was on the surface during the decomposition. The TiO2-Al2O3 catalyst that was prepared by the sol-gel method contained the same composition as the optimal catalyst, TiO2(10)/Al2O3, however, it showed a very low NO decomposition activity, resulting only about 10% decomposition during 1 h period.
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