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ZSM-5 촉매상에서 메탄올의 전환반응, 반응특성과 안정성
박상언,전학제,Sang Eon Park,Hak Ze Chon 대한화학회 1981 대한화학회지 Vol.25 No.3
형상 선택성 ZSM-5 제올라이트 촉매상에서 메탄올로부터 $C_2-C_{10}4</TRX>의 탄화수소 형성을 조사하였다. 메탄올로 부터 dimethylether를 거쳐 생성되는 $C_2-C_5$의 올레핀들이 ZSM-5의 강한 산점에서 고리화 반응등에 의하여 방향족 화합물이 많이 포함된 탄화수소화합물로 전환된다고 생각된다. 메탄올의 전환반응에 대한 ZSM-5 촉매의 높은 활성과 활성저하에 대한 안정성은 특유의 교차되는 세공관구조와 소수성에 기인하는 것으로 보인다. The formation of $C_2-C_{10}$ hydrocarbons from methanol over shape-selective ZSM-5 zeolite catalysts is studied. It seems that $C_2-C_5$ olefins formed from methanol via dimethylether are transformed further to higher hydrocarbons containing higher concentration of aromatics by the acid sites of ZSM-5. Unique cross linked channel structure and its hydrophobicity seems to be mainly responsible for its high activity of ZSM-5 catalyst for the conversion of methanol.
ZSM-5 제올라이트 촉매상에서의 메탄올로부터 탄화수소 합성반응
박상언,전학제,Sang Eon Park,Hak Ze Chon 대한화학회 1981 대한화학회지 Vol.25 No.2
$SiO_2$/$Al_2O_3$ 비가 높은 제올라이트 ZSM-5를 합성하여 메탄올의 탄화수소로의 전환반응을 조사하였다. 메탄올이 전환되어 올레핀, 파라핀, 시클로파라핀 및 방향족화합물이 생성되었으며 특히 방향족 화합물에 대한 큰 선택성을 보여 주었고 1,3,5-trimethylbenzene의 크기정도에 제한된 형상선택성 촉매작용임을 알 수 있었다. 수소형태(HZSM-5)가 활성이 커, 메탄올이 탈수되어 일어나는 잇단 복잡한 반응들이 산촉매반응이 주임을 보여 주었다. ZSM-5와 구조가 유사한 mordenite와 3차원구조를 지닌 faujasite 촉매에서의 메탄올의 반응으로 구조적 영향과 TPD실험에 의한 산점분포를 비교한 결과 메탄올로부터 방향족화합물에 이르기까지의 탄화수소 합성에서의 ZSM-5 제올라이트의 촉매작용은 높은 실리카함량에 기인한 강한 산성과 교차하는 세공관 구조에 의한 분자체 효과에 의한 것으로 볼 수 있다. The conversion of methanol to hydrocarbons has been studied over synthetic ZSM-5 zeolite catalyst having high silica to alumina ratio. The conversion products were olefins, paraffins, cycloparaffins, and aromatics, and the catalyst showed especially high selectivity toward the formation of aromatics. The catalyst showed the shape-selectivity and the size of molecules in the product was limited approximately to the size of 1,3,5-trimethylbenzene. Hydrogen form(HZSM-5) was more active, indicating reactions following the dehydration of methanol seemed to be mainly catalyzed by acid sites. Comparison of the reaction characteristics and acid site distribution of the ZSM-5 catalyst with those of mordenite and faujasite type catalysts suggests that cross-linked pore channel structure and the strong acidity of the ZSM-5 catalyst are primarily responsible for the selective formation of aromatics over this catalyst.
박상언,윤재복,유상신,Park, S.A.,Yoon, J.B.,Yoo, S.S. 대한설비공학회 1992 설비공학 논문집 Vol.4 No.4
An experimental investigation of the stenosis effects on the pressure drop and flow change in the internal flow is presented. Stainless steel tubes of small diameter(3.175mm, 3.4mm) are used for the test section of the flow loop. Percent contraction ranges from 35% to 83% and the stenosis length ratio (L/d) is varied from 2.8 to 8. Water and aqueous glycerol solutions are used for Newtonian fluids and polymer solutions of Separan AP-273 (500 wppm, 1000 wppm) for non-Newtonian fluids. Pressure loss coefficients of non-Newtonian fluids decrease just as those of Newtonian fluids. The loss coefficients of Newtonian and non-Newtonian fluids increase as the percent contraction increases and the loss coefficients of non-Newtonian fluids are larger than those of Newtonian fluids for the same stenosed tube. The loss coefficient increases as the stenosis length ratio increases.
속도선택 포화흡수분광을 이용한 분산형 신호의 관측 및 반도체 레이저의 주파수안정화
박상언,조혁,권택용,양성훈,이호성,Park, Sang-Eon,Cho, Hyuck,Kwon, Taeg-Yong,yang, Sung-Hoon,Lee, Ho, Seung 한국광학회 2001 한국광학회지 Vol.12 No.3
세슘 $D_1$전이선에 해당하는 파장 894 nm의 레이저시스템을 제작하여 포화흡수광 실험을 하였다. 포화흡수증기셀 내에서 조사광을 펌프광에 대해 일정한 각도로 교차시켜서 속도선택적인 포화흡수분광신호를 관찰하였다. 이신호는 펌프광과 조사광의 교차하는 각도와 위치에 따라 변했다. 이때 두 개의 조사광에 의해 만들어진 속도선택 포화흡수분광신호들의 차이를 측정함으로써 분산모양의 주파수 분별신호를 만들 수 있었다. 이를 이용하여 주파수 변조없이 반도체 레이저의 주파수를 안정화할수 있었다. 그 결과 주파수 안정도$\sigma_y(\tau=1s)=7$\times10^{-12}$, $\sigma_f(\tau=1s)=2.4kHz$ 이었다. We observed a velocity-selective saturated absorption spectrum when the pump beam intersects the probe beam at a finite angle with a saturated absorption spectroscopic configuration in the cesium vapor cell. And we also observed a dispersion-like signal by measuring the difference between two velocity-selective absorption spectra produced by two parallel probe beams intersected by one pump beam. The dispersion-like signal was changed with the crossing angle and the crossing position of the pump and probe beams and compared with the calculated result. The dispersion-like signal was used as a frequency discriminator, and the laser could be frequency-stabilized without any frequency modulation. As a result, the square root of Allan variance was $\sigma_y(\tau=1s)=7$\times10^{-12}$, for the sampling time of 1 s.of 1 s.
박상언,김동수,김만,장도연,권식철,Park, Sang-Eon,Kim, Dong-Su,Kim, Man,Jang, Do-Yeon,Gwon, Sik-Cheol 한국기계연구원 2001 硏究論文集 Vol.31 No.-
In chromium electrodeposition, crack is inevitably accompanied by chromium layer. Behavior of crack formation and crack density were different from the plating conditions such as current density, temperature, waveform of applied current and so on. And cracks have an influence on the corrosion resistance of chromium deposit, because corrosion occurs through the network of cracks between deposit and substrate. Therefore, many researches have been achieved in order to remove the cracks in chromium deposit. Formation of double layers, Cr/Cr and Ni/Cr were investigated to increase corrosion resistance of chromium deposit in this study. As pretreatment prior to outer chromium coating, acid pickling and current control method were examined. Cracks in cross-section of each sample were observed with SEM and CASS(Copper modified acetic acid salt spray) test was performed to evaluate corrosion resistance. It was found that corrosion resistance of Cr/Cr and Ni/Cr double layers were superior to Cr or Ni single layer from the results of CASS test.