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FT 합성반응용 철촉매에 미치는 촉매특성에 미치는SiO<sub>2</sub> 첨가효과
천동현(Chun, Dong-Hyun),김학주(Kim, Hak-Joo),현순택(Hyun, Sun-Taek),양정훈(Yang, Jung-Hoon),이호태(Lee, Ho-Tae),양정일(Yang, Jung-Il),정헌(Jung, Heon) 한국신재생에너지학회 2009 한국신재생에너지학회 학술대회논문집 Vol.2009 No.06
Precipitated iron-based catalysts are highly promising for the Fischer-Tropsch synthesis (FTS), in particular for the low temperature FTS below 280?C, because of their high activity and low cost. SiO₂ is an essential promoter for the precipitated iron-based catalysts to improve the attrition strength and physical stability. In this study, we carried out FTS over precipitated iron-based catalysts with and without SiO₂ in a fixed-bed reactor. The catalysts were prepared by a conventional co-precipitation method. In case of the catalysts with SiO₂, we used two comparative preparation methods, i.e., incorporation of SiO₂ before precipitation (denoted as precipitated SiO₂) and after precipitation (denoted as binder SiO₂), respectively. The addition of SiO₂ crucially affects both physico-chemical properties and catalytic peformance of precipitated iron-based catalysts.
SiO<sub>2</sub> 원료물질에 따른 Fischer-Tropsch 합성반응용 Fe계 촉매의 성능변화
천동현(Chun, Dong Hyun),김학주(Kim, Hak-Joo),현순택(Hyun, Sun-Taek),이호태(Lee, Ho-Tae),양정일(Yang, Jung-Il),양정훈(Yang, Jung Hoon),정헌(Jung, Heon) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.06
Fe계 촉매는 FT(Fischer-Tropsch) 합성반응에 매우 유망한 촉매로 주목받고 있으며, 280?C 미만의 저온 FT 합성반응의 경우, 침전법이 Fe계 촉매의 가장 전형적인 제조방법으로 알려져 있다. Fe계 촉매에 첨가되는 조촉매로는 Cu, K, SiO₂ 등이 가장 대표적이며, 이 중에서 특히 구조 조촉매로 첨가되는 SiO₂는 Fe계 촉매의 기계적 강도를 향상시킬 뿐만 아니라, 촉매의 성능에도 크게 영향을 미치는 것으로 보고되고 있다. 본 연구에서는 침전법을 이용하여 저온 FT 합성반응용 Fe계 촉매를 제조하였고, 구조 조촉매로 첨가한 SiO₂의 원료물질에 따른 Fe계 촉매의 성능변화를 조사하였다. SiO₂의 원료물질로는 콜로이드 SiO₂와 분말 SiO₂를 이용하였으며, 분말 SiO₂를 이용한 촉매가 콜로이드 SiO₂를 이용한 촉매보다 다소 높은 CO 전환율 및 중질탄화수소 선택도를 나타내는 것을 확인하였다.
철 촉매를 이용한 Fischer-Tropsch 합성 반응과 수성 가스 전환 반응에 대한 반응 속도 연구
양정일 ( Jung Ii Yang ),천동현 ( Dong Hyun Chun ),박지찬 ( Ji Chan Park ),정헌 ( Heon Jung ) 한국화학공학회 2012 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.50 No.2
The kinetics of the Fischer-Tropsch synthesis and water gas shift reactions over a precipitated iron catalyst were studied in a 5 channel fixed-bed reactor. Experimental conditions were changed as follows: synthesis gas H2/CO feed ratios of 0.5~2, reactants flow rate of 60~80ml/min, and reaction temperature of 255~275˚C at a constant pressure of 1.5 MPa, The reaction rate of Fischer-Tropsch synthesis was calculated from Eley-Rideal mechanism in which the rate-determining step was the formation of the monomer species (methylene) by hydrogenation of associatively adsorbed CO. Whereas water gas shift reaction rate was determined by the formation of a formate intermediate species as the rate-determining step. As a result, the reaction rates of Fischer-Tropsch synthesis for the hydrocarbon formation and water gas shift for the CO2 production were in good agreement with the experimental values, respectively. Therefore, the reaction rates (r FT, r WGS, -r CO) derived from the reaction mechanisms showed good agreement both with experimental values and with some kinetic models from literature.
고분자전해필 연료전지 분리판용 316 스테인리스강의 전기전도도에 미치는 Nb, Ti 첨가 및 표면처리 효과
이석현(Lee, Seok-Hyun),김정헌(Kim, Jeong-Heon),김민철(Kim, Min-Chul),천동현(Chun, Dong-Hyun),위당문(Wee, Dang-Moon) 한국신재생에너지학회 2006 한국신재생에너지학회 학술대회논문집 Vol.2006 No.11
Nb and Ti were added to 316 stainless steel, and then heat-treatments and surface treatments were performed on the 316 stainless steel and the Nb- and Ti-added alloys. All samples indicated enhanced electrical conductivity after surface treatments, whereas they showed low electrical conductivity before surface treatments due to the existence of non-conductive passive film on the alloy surface. In particular, the Hb- and Ti-added alloys showed remarkable enhancement of electrical conductivity compared to the original alloy, 316 stainless steel. Surface characterization revealed that small carbide particles formed on the alloy surface after surface treatments, while the alloys indicated flat surface structure before surface treatments. Cr_{23}C<sub>6</sub> mainly formed on the 316 stainless steel, and NbC and TiC mainly formed on the Nb- and Ti-added alloys, respectively. We attribute the enhanced electrical conductivity after surface treatments to the formation of these carbide particles, possibly acting as a means of electro-conductive channel through the passive film. Furthermore, NbC and TiC are supposed to be more effective carbides than Cr_{23}C<sub>6</sub> as electro-conductive channels of stainless steel