본 연구에서는 순수 TiO₂ 및 molybdenum doped TiO₂(Mo/Ti) 혼합광촉매를 제조하여 대기오염원인 휘발성 유기화합물(volatile organic compound, VOC) 의 일종인 trichloroethylene(TCE)을 광분해 반응하였다. 제조한 광촉매를 유리구슬에 코팅하여 튜브형 반응기에 충진하였으며, 초기농도 150ppm 인 TCE를 순환 반응하여 TCE 및 TCE의 중간생성물을 GCMSD로 분석하여 반응경로를 파악하였다. 반응결과 중간생성물로 DCA(Dichloroacetyl Chloride), chloroform, Carbon tetrachloride, tetrachloroethane, pentachoroethane이 검출되었다. 또 산소농도 변화에 대한 TCE 및 중간 생성물의 제거경향을 파악하였는데 그 결과 산소의 양이 증가할수록 중간생성물이 더 빠르게 감소함이 관찰되어 산소의 영향이 크다는 것을 알 수 있었다. 제조된 촉매별로 TCE의 분석결과 450℃에서 2시간 열처리한 순수 TiO₂(anatase)가 가장 효율이 좋았으며 UV/Visible spectrum으로 촉매의 흡수파장을 측정한 결과 순수 TiO₂의 흡수파장대와 비교하여 Mo의 첨가량이 증가할수록 가시광선 영역으로 red-shift되는 것을 관찰할 수 있었다. 또한 제조된 광촉매들을 DTA-TG, XRD로 분석한 결과 300-450℃에서 anatase로의 상전이가 일어남을 관찰할 수 있었으며, 제조된 광촉매를 이용한 액상 dichloroacetic acid(DCA) 분해 반응의 photonic efficiency(P.E.)를 측정해 본 결과 순수 TiO₂(P.E.=15%)가 Mo/Ti(P.E.=11%)보다 우수함이 관찰되었다.

Photocatalysis of trichloroethylene (TCE) with TiO₂ and molybdenum-doped TiO₂(Mo/Ti) mixed oxide was studied in this work using a tubular quartz reactor packed with photocatalyst-coated glass beads. The initial TCE concentration of 150 ppm, was recirculated with the different inlet oxygen concentration. The change in intermediates during photoreaction of TCE was monitored with a GC-ECD and a GC-MSD. Dichloroacethyl chloride(DCAC), chloroform, carbon tetra chloride, tetrachloroethane and pentachloroethane were identified as intermediates. It was observed that oxygen concentration affected the formation and the disappearance of intermediates. As oxygen concentration increased disappearance rates of intermediates and TCE increased. Pure TiO₂ increased. Pure TiO₂ thermally treated at 450℃ for 2h exhibited the best conversion ratio of TCE among other photocatalysts tested. The characteristics of the photocatalysts were also examined employing UV/Visible spectrophotometer, TG-DAT, and XRD. Absorption spectra of UV/VIS indicated that the onset of absorption curve was red-shifted as Mo concentration was increased. The phase change to anatase was observed with heat treatment at 300-450℃. The photonic efficiency was measured using dichloroacetic acid, and 15% of photonic efficiency for pure TiO₂ and 11% for Mo/Ti were obtained.

TiO₂ Mo/Ti Mixed Oxide Photocatalysis TCE

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