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김헌덕(HUN-DUK KIM),김종인(JONG-IN KIM),류청로(CHEONG-RO RYU) 한국해양공학회 2001 韓國海洋工學會誌 Vol.15 No.4
The Water quality in Yongil Bay is getting worse due to the sewage and the waste water from the surrounding industrial complex. The study aims to simulate the current system that is necessary to build ecosystem model for the optium water quality control and clarify the correlation of current system characteristics with water quality in Yongil Bay. To clarify the characteristics of coastal water movement system and verify the applicability of the 3-D model, the current system was simulated using 3-D baroclinic model which considers tidal current and density effects. As the results of numerical experiments, it is proved the 3-D model is the most applicable on appearing the current system of the stratificated Yongil Bay by the difference of density. From the results of simulation considered tidal current only, it can be clarified that the water body flows in the inner bay through the bottom layer and flows out the outer bay through the surface layer in Yongil Bay. And the fresh water from the Hyongsan river and the thermal discharge from POSCO have a little effect on the current system in Yongil Bay, but the diffusion of heat and salt has an important effect upon the formation of the density stratification. The characteristics of the water quality distribution is closely related with the current structure characteristics as well as the tidal residual current system in Yongil Bay.
변형된 ZSM-5 제올라이트에서 톨루엔의 메탄올에 의한 알킬화반응
김장희,김헌덕,이태진 嶺南大學校 工業技術硏究所 1995 工業技術硏究所論文集 Vol.23 No.1
Vapor phase catalytic alkylation of toluene with methanol over ZSM-5 zeolites and modified ZSM-5 zeolites was extensively investigated. The main product was xylene isomers formed by benzene ring alkylation. However, styrene and ethylbenzene made by side-chain alkylation was not formed over any modified ZSM-5 zeolites. The selectivity of para-xylene was improved by increasing Si/Al ratio, decreasing strong acid sites, and increasing basicity. The yield of xylenes decreased in the catalyst sequence HZSM-5>NaZSM-5>MgO/ZSM-5>KMg ZSM-5. It was thought that the lack of side-chain alkylation correlated with no formation of formaldehyde as key intermediate over any modified ZSM-5 zeolites. The variations of the reaction rate were concluded to be governed mainly by the concentrations of methoxonium ions and adsorbed toluene based on the reaction mechanism. The active sites for xylenes production were concluded to be medium acid sites.
염기성 제올라이트상에서 톨루엔의 메탄올에 의한 측쇄 알킬화반응
이태진,장원철,김헌덕 한국화학공학회 1994 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.32 No.3
톨루엔의 메탄올에 의한 알킬화반응을 대기압, 420℃, 2-6의 톨루엔/메탄올 몰비로 흐름반응기에서 수행하였다. 촉매들은 상용의 X형 제올라이트를 알칼리 양이온교환 또는 NaN₃의 함침법으로 만들었다. 자일렌 수율은 NaX>Na-cluster X>KX순서로 감소하였으며, 스티렌과 에틸벤젠의 수율은 역순으로 나타났다. 이러한 결과들은 고리 알킬화반응과 측쇄 알킬화반응이 각각 촉매의 산성도와 염기도에 의존함을 시사한다. DSC로 산성도와 염기도의 분포를 아울러 조사하였고 촉매들의 성능과 결부시켰다. 반응과정에서 촉매표면의 산·염기 성질이 중요한 역할을 한다고 판단된다. Catalytic alkylation of toluene with methanol was studied at atmospheric pressure, 420℃, and toluene/methanol feed molar ratios of 2-6 in a fixed bed reactor. Catalysts were prepared from the commercial X-type zeolite by ion exchange with alkali cations and/or impregnation of NaN₃. The yield of xylenes decreased in the catalyst sequence NaX>Na-cluster X>KX; the reverse tendency was found for the yield of styrene and ethylbenzene. These results suggest that benzene ring alkylation and side-chain alkylation depend on the catalyst acidity and basicity, respectively. The distributions of the acidity and basicity were also investigated by differential scanning calorimetry(DSC) and correlated with the performance of the catalysts. It was thought that a surface acid property as well as a surface base property played an important role in the course of the reaction.