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솔-젤법으로 제조된 TiO<sub>2</sub>-SiO<sub>2</sub> 촉매상에서 CFC-113의 산화분해반응에 관한 연구
장원철,이두형,이태진,Chang, Won-Chul,Lee, Doo-Hyoung,Lee, Tae-Jin 한국공업화학회 1999 공업화학 Vol.10 No.7
CFCs(chlorofluorocarbons)에 의한 여러 지구 환경문제들이 발생되고 있는 가운데, 사용후 회수된 CFCs에 대하여 보다 안전한 파괴방법이 요구되고 있다. 이런 관점에서 CFC-113의 분해를 위한 보다 좋은 조건을 개발하고자 접촉 산화분해반응하에서 솔-젤법으로 만들어진 에어로젤 $TiO_2-SiO_2(ATS)$ 촉매에 대하여 본 연구를 행하였다. 솔-젤법으로 만들어진 ATS 촉매가 초기 활성에서 우수하였지만 반응시간이 경과함에 따라 침전법에 의해 제조된 촉매보다 급격한 활성저하를 나타내었다. 이런 비활성화의 원인은 SEM-EDX와 XRD의 분석으로부터 생성가스 $F_2$에 의한 촉매표면의 Si 원자에 대한 결합, 유출에 기인된 것으로 판단되었다. 그리고 ATS 촉매제조과정에서 prehydrolysis 방법으로 처리된 촉매가 촉매 표면의 산성도가 증가됨에 따라 촉매활성이 지속적으로 유지되고 촉매 피독에 의한 비활성화가 느리게 진행되는 것이 관찰되었다. 또한 ATS 촉매 반응에 있어서 Ti의 mol 비가 80%까지 증가함에 따라서도 산성도가 증가되어 본 반응에서 활성 유지와 비활성화 진행속도가 느리게 됨을 발견할 수 있었다. 한편, ATS 촉매에 대해 황산이온처리된 $ATS/SO_4{^{2-}}$ 촉매가 촉매의 활성유지와 비활성화 방지에 있어서 우수한 성질을 나타내었다. 그러므로 본 반응에 있어서 촉매 표면에 대한 황산이온의 처리가 촉매의 비활성화 방지에 기여할 수 있음을 알 수 있었다. The global environmental problems have been caused by the release of CFCs. Therefore, methods for safe destruction of recoverd CFCs will be eventually needed. The objective of this study was to develop and test a catalyst operating at a mild condition for the decomposition of CFC-113. In this work, catalytic oxidative decomposition of CFC-113 was carried out over aerosol $TiO_2/SiO_2(ATS)$ catalysts prepared by the sol-gel method. All ATS catalysts(Ti/Si mol ratio=1, 2, 2.33, 4) showed high initial activity. However, the deactivation of ATS catalysts was found that more remarkable due to an attack of fluorine and the destruction of ATS structure(Si-F reaction) from analyses of SEM-EDX, XRD than $TiO_2/SiO_2(ATS)$ catalyst prepared by the precipitation method. ATS catalysts prepared by more acidic prehydrolysis condition were found to have still more activity and longer life-time by increasing of acidity. The activity of ATS catalyst also depend on the content of $TiO_2$. There was reason that the acidity of the ATS catalyst was increased with the increased content of $TiO_2$ from 50 to 80 mol %. Solid superacid catalyst ($ATX/SO_4{^{2-}}$) modified with $H_2SO_4$ solution was prepared for high activity and lower deactivation. The reaction of $ATS/SO_4{^{2-}}$ catalyst also exhibited even higher activity and lower deactivation than the original ATS catalyst. It is suggested that the addition of the sulphate species clearly inhibit the deactivation.
장원철 ( Won Chul Chang ),김병국 ( Byung Kook Kim ),김미진 ( Mi Jin Kim ),유광하 ( Kwang Ha You ),전혜정 ( Hae Jeong Jeon ) 대한내과학회 2005 대한내과학회지 Vol.69 No.2
A pseudo-Cushing`s state can be defined as some or all of the clinical features of Cushing`s syndrome together with some evidence for hypercortisolism. It may be related to depression, alcohol abuse and obesity. Its manifestation may be transient and resolved with abstinence from causing factors. We report a case of a 70-year-old woman with unilateral nonfunctioning adrenal adenoma and geriatric depressive disorder, which diagnosed by Geriatric Depression Scale (GDS). She showed clinical and/or biochemical features of Cushing`s syndrome. Low dose and high dose dexamethasone suppression tests were not identical to those in ACTH independent Cushing`s syndrome. Few cases of pseudo-Cushing`s syndrome were reported previously in Korea but there was no report about pseudo-Cushing`s syndrome combined with nonfunctional adrenal adenoma.(Korean J Med 69:216-221, 2005)
임진규,장원철,이태진,심재진,최대기,이윤용 ( Jin Gyu Lim,Won Chul Chang,Tae Jin Lee,Jae Jin Shim,Dae Ki Choi,Youn Yong Lee ) 한국화학공학회 1994 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.32 No.3
Adsorption equilibria of Freon-113(trichlorotrifluoroethane, CCl₂FCClF₂) on two activated carbons were measured at 298-473 K by using a static adsorption apparatus. Granular activated carbon(Norit B4, crushed 20-40 mesh) and activated carbon fiber(KF-1500) were used as adsorbents. They were regenerated overnight at 473 K under vacuum condition before experiments. The portion of the reversible to the total uptake increased with temperature and the adsorption at 473 K was found to be completely reversible. All the isotherms obtained in this study were type I. They showed no apparent hysteresis. The heat of adsorption calculated from Clausius-Clapeyron equation remained nearly constant irrespective of the surface coverage. Experimental data were correlated by BET, Langmuir, and Dubinin-Astakhov equations.