Korean Chemical Engineering Research

The Korean Institute of Chemical Engineers (한국화학공학회)
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Effects of SiO2 Incorporation on Catalytic Performance and Physico-Chemical Properties of Iron-Based Catalysts for the Fischer-Tropsch Synthesis

Fischer-Tropsch 합성반응용 Fe계 촉매의 성능 및 물리화학적 특성에 미치는 SiO2 첨가효과

  • Hyun, Sun-Taek (Department of Chemical and Biological Engineering, Korea University) ;
  • Chun, Dong Hyun (Clean Fossil Energy Research Center, Korea Institute of Energy Research) ;
  • Kim, Hak-Joo (Clean Fossil Energy Research Center, Korea Institute of Energy Research) ;
  • Yang, Jung Hoon (Clean Fossil Energy Research Center, Korea Institute of Energy Research) ;
  • Yang, Jung-Il (Clean Fossil Energy Research Center, Korea Institute of Energy Research) ;
  • Lee, Ho-Tae (Clean Fossil Energy Research Center, Korea Institute of Energy Research) ;
  • Lee, Kwan-Young (Department of Chemical and Biological Engineering, Korea University) ;
  • Jung, Heon (Clean Fossil Energy Research Center, Korea Institute of Energy Research)
  • 현순택 (고려대학교 화공생명공학과) ;
  • 천동현 (한국에너지기술연구원 청정화석연료연구센터) ;
  • 김학주 (한국에너지기술연구원 청정화석연료연구센터) ;
  • 양정훈 (한국에너지기술연구원 청정화석연료연구센터) ;
  • 양정일 (한국에너지기술연구원 청정화석연료연구센터) ;
  • 이호태 (한국에너지기술연구원 청정화석연료연구센터) ;
  • 이관영 (고려대학교 화공생명공학과) ;
  • 정헌 (한국에너지기술연구원 청정화석연료연구센터)
  • Received : 2009.12.14
  • Accepted : 2010.01.13
  • Published : 2010.06.30
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Abstract

The FTS(Fischer-Tropsch synthesis) was carried out over precipitated iron-based catalysts with or without $SiO_2$ in a fixed-bed reactor at $250^{\circ}C$ and 1.5 MPa. The catalysts with $SiO_2$ showed much higher catalytic activity for the FTS than those without $SiO_2$, displaying excellent stability during 144 h of reaction. The X-ray diffraction and $N_2$ physisorption revealed that the catalysts with $SiO_2$ showed enhanced dispersion of $Fe_2O_3$ compared with those without $SiO_2$. Also, the results of temperature-programmed reduction by $H_2$ showed that the addition of $SiO_2$ markedly promoted the reduction of $Fe_2O_3$ into $Fe_3O_4$ and FeO at low temperatures below $260^{\circ}C$. In contrast, surface basicity of the catalysts, which was analyzed by temperature-programmed desorption of $CO_2$, decreased as a result of $SiO_2$ addition. We attribute the high and stable performance of the catalysts with $SiO_2$ to the improved dispersion and reducibility by the $SiO_2$ addition.

공침법을 이용하여 구조 조촉매인 $SiO_2$가 첨가된 Fe계 촉매와 $SiO_2$가 첨가되지 않은 Fe계 촉매를 제조하였고, 이러한 두 가지 촉매를 이용하여 $250^{\circ}C$의 온도 및 1.5 MPa의 압력에서 Fischer-Tropsch 합성반응을 수행하였다. $SiO_2$를 첨가한 Fe계 촉매가 $SiO_2$를 첨가하지 않은 Fe계 촉매보다 현저히 우수한 촉매활성을 나타내었고, 144시간의 반응시간동안 뛰어난 촉매안정성을 나타내었다. X-선 회절 및 $N_2$의 물리흡착을 통하여 촉매의 결정구조 및 세공구조를 분석한 결과, $SiO_2$를 첨가할 경우 Fe계 촉매의 분산도가 향상되는 것을 발견할 수 있었다. 또한 $H_2$-TPR(temperature-programmed reduction) 분석결과를 통해, $SiO_2$를 첨가할 경우 $260^{\circ}C$ 이하의 저온 영역에서 $Fe_2O_3$의 $Fe_3O_4$ 및 FeO로의 환원이 촉진되는 것을 확인하였다. 반면 $CO_2$-TPD(temperature-programmed desorption) 분석결과에 의하면, $SiO_2$를 첨가한 결과 촉매의 표면 염기도는 감소하였다. 따라서 $SiO_2$를 첨가한 촉매가 $SiO_2$를 첨가하지 않은 촉매보다 우수한 촉매성능을 나타내는 것은, $SiO_2$를 첨가함에 따라 촉매의 분산이 증진되고 환원이 촉진된 것이 주요 원인인 것으로 생각된다.

Keywords

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