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xTiO2 - y SiO2 광촉매에 의한 유기물의 광분해
양천희(Chun Hoi Yang),이철우(Chul Woo Lee),홍필선(Phil Sun Hong),이원묵(Won Mook Lee) 한국물환경학회 2000 한국물환경학회지 Vol.16 No.1
TiO₂ and x TiO₂- y SiO₂ system photocatalysts were developed by sol-gel method based on the change of production parameters, and their structure of crystallization and the specific surface area were measured. Considering the efficiency of the ethanol and phenol degradation using the catalyst, the conclusions were obtained as follows: ①. By means of X-ray analysis of TiO₂ powder that is obtained from water and Titanium alkoxide with various molar ratios, it is shown that crystal structure of anatase type is a dominating structure and, on the other hand, the structure of rutile also partly exists. The specific surface area is at its maximum value at R=6, which is the molar ratio of water vs. alkoxide, whereas its value goes down as the molar ratio increases. ②. xTiO₂- y SiO₂ system photocatalysts were developed from Titanium and Silicon alkoxide by a hetero-condensation process. The increase of SiO₂ contents causes the decrease of the degree of crystallization of the gel, whereas the specific surface area preferentially increases. It is shown that more than 90% of ethanol and phenol are degraded when reaction time is about three and an hours, and the maximum degradation rate of ethanol and phenol is shown in 60TiO₂-40SiO₂ catalyst.
n-Octane의 개질반응에서 FAU와 MF1 촉매의 탈 알루미늄에 의한 Si/A1비의 영향
유용호 ( Yong Ho Yu ),정우진 ( Woo Jin Chung ),이철우 ( Chul Woo Lee ),오민 ( Min Oh ),이원묵 ( Won Mook Lee ) 한국공업화학회 2003 공업화학 Vol.14 No.2
제올라이트에서 Si/Al의 조성비는 산도에 큰 영향을 주므로 촉매의 활성 및 선택도도 큰 영향을 받는다. 본 연구에서는 상용화된 FAU 및 MFI 제올라이트를 탈 알루미늄 하여 산도를 변화시킨 후 노르말 옥탄의 개질 반응에서의 촉매특성을 살펴보았다. FAU와 MFI 제올라이트의 탈 알루미늄은 각각 열처리, 수증기 처리, 그리고 질산 처리 등 세 가지 서로 다른 방법으로 수행하였고, 처리된 제올라이트의 물성은 BET, XRE, SEM-EDS, TPD, FT-IR 등을 사용하여 측정하였다. 변형된 제올라이트 촉매들은 본 제조 조건에서 결정성을 그대로 유지하였으며, Si/Al 비는 3에서 30까지 증가하였고 산도는 크게 감소하였다. n-Octan의 개질 반응에서 촉매의 활성은 MFI계 촉매가 FAU계 촉매보다 더 우수하였고, 열처리한 경우가 수증기 처리한 경우보다 활성이 더 크게 나타났다. 수증기 처리한 경우는 열처리한 경우보다 촉매의 활성은 낮았지만 BTX 생성 억제 효과는 더 우수하였고, 산도가 높은 FAU 촉매는 분해반응에서 우수한 활성을 나타내었다. 개질 반응에서 일어나는 분해반응, 탈 수소반응 그리고 이성화반응 등을 종합적으로 고려하면 열처리에 의하여 변형된 MFI계 촉매가 가장 우수하였다. The catalytic activity and selectivity of zeolites are significantly influenced by the Si/Al ratio, because it has strong effects on the acidity of zeolites. In this research, the catalytic characteristics were investigated by using dealuminated FAU and MFI zeolites as the catalysts in the reforming of n-octane. Dealumination of zeolites was carried out in three different processes, i. e., thermal, steam, and nitric acid treatment, and their properties were measured by BET, XRD, SEM-EDS, TPD and FT-IR. The crystalline structure of zeolites was maintained after dealumination. Si/Al ratio was increased from 3 to 30, and the acidity was decreased drastically as Si/Al ratio increased. The catalytic activity of dealuminated MFI zeolite was superior to that of FAU zeolie. Steam treated catalyst showed lower activity than thermally treated one, but it showed better performance in the inhibition of BTX generation. FAU zeolite with high acidity showed good selectivity to the decomposition reaction. In conclusion, thermally treated MEI zeolite showed the highest activity in the n-octane reforming, considering all the reactions; decomposition, dehydrogenation and isomerization.