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

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$$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

References

  1. Dry, M. E., "The Fischer-Tropsch process-commercial aspects", Catal. Today, 6(3), 183-210(1990). https://doi.org/10.1016/0920-5861(90)85002-6
  2. Anderson, R. B., The Fischer-Tropsch Synthesis, Academic press. Inc., Orlando 1-225(1984).
  3. Dry, M. E., Encyclopedia of Catalysis Volume 3, Wiley-interscience, New Jersey, 347-403(2003).
  4. Steynberg, A. P. and Dry, M. E., Fischer-Tropsch Technology, Elsevier, Amsterdam, 19-593(2004).
  5. An, X., Wu, B., Wan, H.-J., Li, T.-Z., Tao, Z.-C., Xiang, H.-W. and Li, Y.-W., "Comparative Study of Iron-based Fischer-Tropsch Synthesis Catalyst Promoted with Potassium or Sodium," Catal. Comm., 8, 1957-1962(2007). https://doi.org/10.1016/j.catcom.2007.03.016
  6. Zhang, C. H., Yang, Y., Teng, B. T., Li, T. Z., Zheng, H. Y., Xiang, H. W. and Li, Y. W., "Study of an Iron-manganese Fischer-Tropsch Synthesis Catalyst Promoted with Copper," J. Catal., 237, 405-415(2006). https://doi.org/10.1016/j.jcat.2005.11.004
  7. Wan, H. J., Wu, B. S., Tao, Z. C., Li, T. Z., An, X., Xiang, H. W. and Li, Y. W., "Study of an iron-based Fischer-Tropsch synthesis catalyst incorporated $SiO_2$," J. Mol. Catal. A-Chem., 260, 255-263(2006). https://doi.org/10.1016/j.molcata.2006.07.062
  8. Yang, Y., Xiang, H. W., Tian, L., Wang, H., Zhang, C. H., Tao, Z.C., Xu, Y. Y., Zhong, X. B. and Li, Y. W., "Structure and Fischer-Tropsch Performance of Iron-manganese Catalyst Incorporated with $SiO_2$," Appl. Catal. A-Gen., 284, 105-122(2005). https://doi.org/10.1016/j.apcata.2005.01.025
  9. Jun, K. W., Roh, H. S., Kim, K. S., Ryu, J. S. and Lee, K. W., "Catalytic Investigation for Fischer-Tropsch Synthesis from Biomass Derived Syngas," Appl. Catal. A-Gen., 259, 221-226(2004). https://doi.org/10.1016/j.apcata.2003.09.034
  10. Dlamini, H., Motjope, T., Joorst, G., Stege, G. and Mdleleni, M., "Changes in Physico-chemical Properties of iron-based Fischer-Tropsch Catalyst Induced by $SiO_2$ Addition," Catal. Lett., 78, 201-207(2002). https://doi.org/10.1023/A:1014953201451
  11. Zhang, C. H., Wan, H. J., Yang, Y., Xiang, H. W. and Li, Y. W., "Study on the Iron-silica Interaction of a co-precipitated Fe/$SiO_2$ Fischer-Tropsch Synthesis Catalyst," Catal. Comm., 7, 733-738(2006). https://doi.org/10.1016/j.catcom.2006.03.018
  12. Hou, W., Wu, B., An, X., Li, T., Tao, Z., Zheng, H., Xiang, H. and Li, Y., "Effect of the Ratio of Precipitated $SiO_2$ to Binder $SiO_2$ on Iron-based Catalysts for Fischer-Tropsch Synthesis," Catal. Lett., 119, 353-360(2007). https://doi.org/10.1007/s10562-007-9244-0
  13. Bukur, D. B., Lang, X., Mukesh, D., Zimmerman, W. H., Rosynek, M. P. and Li, C., "Binder/Support Effects on the Activity and Selectivity of iron Catalysts in the Fischer-Tropsch Synthesis," Ind. Eng. Chem. Res., 29, 1588-1599(1990). https://doi.org/10.1021/ie00104a003
  14. Basu, P. K., Basu, S. B., Mitra, S. K. and Dasandhi, Y. C., "The Role of Silica in the Conversion of Syngas to Middle Distillate," Stud. Surf. Sci. Catal., 133, 277-284(1998).
  15. Zhao, G., Zhang, C., Qin, S., Xiang, H. and Li, Y., "Effect of Interaction Between Potassium and Structural Promoters on Fischer-Tropsch Performance in Iron-based Catalysts," J. Mol. Catal. A-Chem., 286, 137-142(2008). https://doi.org/10.1016/j.molcata.2008.02.019
  16. Hou, W., Wu, B., Yang, Y., Hao, Q. and Tian, L., "Effect of $SiO_2$ Content on Iron-based Catalysts for Slurry Fischer-Tropsch Synthesis," Fuel Proc. Tech., 89, 284-291(2008). https://doi.org/10.1016/j.fuproc.2007.11.031
  17. Jothimurugesan, K., Spivey, J. J. and Gangwal, S. K., "Effect of Silica on iron-based Fischer-Tropsch Catalysts," Stud. Surf. Sci. Catal., 119, 215-220(1998). https://doi.org/10.1016/S0167-2991(98)80434-5
  18. ASTM D2887-08, "Standard Test Method for Boiling Range Distribution of Petroleum Fractions by Gas Chromatography," ASTM International, PA(1989).
  19. Phan, H. N. and Datye, A. K., "The Synthesis of Attrition Resistant Slurry Phase Iron Fischer-tropsch Catalysts," Catal. Today, 58, 233-240(2000). https://doi.org/10.1016/S0920-5861(00)00256-X
  20. Herranz, T., Rojas, S., Perez-Alonso, F. J., Ojeda, M., Terreros, P. and Fierro, J. L. G., "Carbon Oxide Hydrogenation over Silicasupported Iron-based Catalysts Influence of the Preparation Route," Appl. Catal. A-Gen., 308, 19-30(2006). https://doi.org/10.1016/j.apcata.2006.04.007
  21. Jin, Y. and Datye, A. K., "Phase Transformations in iron Fischer-Tropsch Catalysts During Temperature-programmed Reduction," J. Catal., 196, 8-17(2000). https://doi.org/10.1006/jcat.2000.3024
  22. Edstrom, J. O., "The Mechanism of Reduction of Iron Oxides," J. Iron Steel Inst., 175, 289-304(1953).
  23. Dry, M. E. and Oosthuizen, G. J., "The Correlation Between Catalyst Surface Basicity and Hydrocarbon Selectivity in the Fischer- Tropsch Synthesis," J. Catal., 11, 18-24(1968). https://doi.org/10.1016/0021-9517(68)90004-3
  24. Miller, D. G. and Moskovits, M., "A Study of the Effects of Potassium Addition to Supported iron Catalysts in the Fischer-Tropsch Reaction," J. Phys. Chem., 92, 6081-6085(1988). https://doi.org/10.1021/j100332a047
  25. Ji, Y.-Y., Xiang, H.-W., Yang, J.-Li, Xu, Y.-Y., Li, Y.-W. and Zhong, B., "Effect of Reaction Condition on the Product Distribution During Fischer-Tropsch Synthesis over an Industrial Fe-Mn Catalyst," Appl. Catal. A-Gen., 214, 77-86(2001). https://doi.org/10.1016/S0926-860X(01)00480-X
  26. Puskas, I. and Hurlbut, R. S., "Comments About the Causes of Deviations from the Anderson-Schulz-Flory Distribution of the Fischer-Tropsch Reaction Products," Catal. Today, 84, 99-109(2003). https://doi.org/10.1016/S0920-5861(03)00305-5
  27. Stenger, H. G. Jr., "Distributed Chain Growth Probabilities for the Fischer-Tropsch Synthesis," J. Catal., 92, 426-428(1985). https://doi.org/10.1016/0021-9517(85)90277-5