Preparation of $WO_3/TiO_2$ and $V_2O_5/TiO_2$ powders and their catalytic performances in the SCR of $NO_x$

$WO_3/TiO_2$$V_2O_5/TiO_2$ 분말의 합성 및 $NO_x$ 제거 SCR특성

  • Lee, Tae-Suk (Department of Materials Engineering, Korea Maritime University) ;
  • Lee, In-Gyu (Department of Materials Engineering, Korea Maritime University) ;
  • Lee, Byeong-Woo (Department of Materials Engineering, Korea Maritime University) ;
  • Shin, Dong-Woo (School of Nano and Advanced Materials Engineering, Gyeongsang National University)
  • 이태석 (한국해양대학교 재료공학과) ;
  • 이인규 (한국해양대학교 재료공학과) ;
  • 이병우 (한국해양대학교 재료공학과) ;
  • 신동우 (경상대학교 나노신소재공학부)
  • Published : 2006.10.31

Abstract

An investigation of the influence of $WO_3$ and $V_2O_5$ catalysts on the microstructure, phase formation and selective catalytic reduction (SCR) efficiency of the synthesized SCR powders has been carried out. A commercial anatase-$TiO_2$ was used as the catalysts support. For $WO_3(10wt%)/TiO_2$, the W loading to the $TiO_2$ support led to the lower in anatase to rutile transition temperature from $1200^{\circ}C$ of $TiO_2$ support to ${\sim}900^{\circ}C$. The transition temperature was also lowered to below $650^{\circ}C$ in the $V_2O_5$(5 and 10 wt%) added composition. The $WO_3(10wt%)/TiO_2$ SCR powder obtained at $450^{\circ}C$ showed near 100% of $NO_x$ conversion efficiency at $350{\sim}400^{\circ}C$ and for the powder prepared at $650^{\circ}C$ the same efficiency was achieved in wider temperature range $300{\sim}400^{\circ}C$. The highest $NO_x$ conversion efficiency of 100% was obtained in the $V_2O_5(5wt%)/TiO_2$ SCR composition calcined at $650^{\circ}C$ in the relatively wider temperature range $250{\sim}350^{\circ}C$, while the catalytic efficiency considerably decreased for the $V_2O_5(10wt%)/TiO_2$. The lowered conversion efficiency of $NO_x$ observed in the $V_2O_5(10wt%)/TiO_2$ composition calcined at $650^{\circ}C$ was considered to be correlated with the lowered surface area resulting from the increased crystallite growth by highly reactive vanadium loading.

Anatase $TiO_2$$WO_3$$V_2O_5$ 촉매를 첨가하여 SCR(selective catalytic reduction)용 분말을 합성하였으며, 촉매 첨가가 합성분말의 미세구조, 상합성 및 SCR 촉매능에 미치는 영향에 대해 연구하였다. 촉매의 지지체로 사용된 상용 anatase-$TiO_2$에서 rutile 단일상으로의 상전이 온도는 $1200^{\circ}C$이었다. 그러나 $WO_3$를 10wt% 첨가하면 이 상전이 온도가 $900^{\circ}C$로 낮아졌으며, $V_2O_5$를 첨가(5와 10wt%)할 경우 $650^{\circ}C$ 이하로 낮아졌다. $450^{\circ}C$에서 제조된 $WO_3(10wt%)/TiO_2$, SCR 분말은 $350^{\circ}C{\sim}400^{\circ}C$에서 100%에 가까운 우수한 $NO_x$ 변환효율을 보였다. $650^{\circ}C$에서 열처리한 경우, 보다 넓은 $300{\sim}400^{\circ}C$온도영역에서 100%가까운 우수한 촉매능을 보였다. $650^{\circ}C$에서 합성된 $V_2O_5(5wt%)/TiO_2$ 촉매분말은 넓은 온도범위($250^{\circ}C{\sim}350^{\circ}C$)에 걸쳐 100%에 달하는 가장 우수한 $NO_x$ 변환효율을 보였다. $650^{\circ}C$ 합성분말의 경우 10wt%의 $V_2O_5$ 첨가는 5wt% $V_2O_5$ 첨가 때 보다 분말물성과 촉매물성이 저하되었으며, 이는 $V_2O_5$의 높은 반응성으로 인한, 촉매의 입자성장에 따른 비표면적감소 때문으로 해석된다.

Keywords

References

  1. J.G. Henry and G.W. Heinke, Environmental science and engineering (Prentice-Hall, NJ, 1989)
  2. G. Baumbach. Air quality control (Springer, Berlin, 1996)
  3. E. Tronconi, L. Lietti, P. Forzatti and S. Malloggi, 'Experimental and theoretical investigation of the dynamics of the SCR-DeNOx reaction', Chem. Engin. Sci. 51(11) (1996) 2965 https://doi.org/10.1016/0009-2509(96)00182-0
  4. G. Busca, L. Lietti, G. Ramis and F. Berti, 'Chemical and mechanical aspects of the selective catalytic reduction of $NO_{x}$ by ammonia over oxide catalysts: A review', Appl. Catal. B: Envir. 18 (1998) 1 https://doi.org/10.1016/S0926-3373(98)00040-X
  5. K. Bourikas, Ch. Fountzoula and Ch. Kordulis, 'Monolayer transition metal supported on titania catalysts for the selective catalytic reduction of NO by $NH_{3}$' , Appl. Catal. B: Envir. 52 (2004) 145 https://doi.org/10.1016/j.apcatb.2004.04.001
  6. A. Andersson and S.L.T. Anderson, in: R.K. Grasselli and J.F. Brazdil (Eds.), Solid state chemistry in catalysis (ACS, Washington, 1985) p.121
  7. J.P. Dunn, P.R. Koppula, H.G. Stenger and I.E. Wachs, 'Oxidation of sulfur dioxide to sulfur trioxide over supported vanadia catalysts', Appl. Catal. B: Envir. 19 (1998) 103 https://doi.org/10.1016/S0926-3373(98)00060-5
  8. A.M. Efstathiou and K. Fliatoura, 'Selective catalytic reduction of nitric oxide with ammonia over $V_{2}O_{5}/TiO_{2}$ catalyst: A steady-state and transient kinetic study', Appl. Catal. B: Envir. 6 (1995) 35 https://doi.org/10.1016/0926-3373(94)00062-X
  9. E. Tronconi, L. Lietti, P. Forzazatti and S. Malloggi, 'Experimental and theoretical investigation of the dynamics of the SCR-DeNOx reaction', Chem. Engin. Sci. 51 (1996) 2965 https://doi.org/10.1016/0009-2509(96)00182-0
  10. R.Q. Long and R.T. Yang, 'Selective catalytic reduction of NO with ammonia over $V_{2}O_{5}\;doped\;TiO_{2}$ pillared clay catalysts', Appl. Catal. B: Envir. 24 (2000) 13 https://doi.org/10.1016/S0926-3373(99)00092-2
  11. I. Nova, L. Lietti, L. Casagrande, L. Dall'Acqua, E. Giamello and P. Forzatti, 'Characterization and reactivity of $TiO_{2}$-supported $MoO_{3}$ De-NOx SCR catalysts', Appl. Catal. B: Envir. 17 (1998) 245 https://doi.org/10.1016/S0926-3373(98)00015-0
  12. J.P. Chen and R.T. Yang, 'Role of $WO_{3}\;in\;mixed\;V_{2}O_{5}-WO_{3}/TiO_{2}$ catalysts for selective catalytic reduction of nitric oxide with ammonia', Appl. Catal. A: General 80(1,2) (1992) 135 https://doi.org/10.1016/0926-860X(92)85113-P
  13. L. Lietti, J.L. Alemany, P. Forzatti, G. Busca, G. Ramis, E. Giamello and F. Bregani, 'Reactivity of $V_{2}O_{5}-WO_{3}/TiO_{2}$ catalysts in the selective catalytic reduction of nitric-oxide by ammonia', Catal. Today 29(1-4) (1996) 143 https://doi.org/10.1016/S0920-5861(96)90012-7
  14. R. Khodayari, C.U. Ingemar Odenbrand, 'Regeneration of commercial $TiO_{2}-V_{2}O_{5}-WO_{3}$ SCR catalysts used in bio fuel plants', Appl. Catal. B: Envir. 30 (2001) 87 https://doi.org/10.1016/S0926-3373(00)00227-7
  15. T. Liuquing, Y Daiqi and L. Hong, 'Catalytic performance of a novel ceramic-supported vanadium oxide catalyst for NO reduction with $NH_{3}$' , Catal. Today 78 (2003) 159 https://doi.org/10.1016/S0920-5861(02)00322-X
  16. S. Djerad, L. Tifouti, M. Crocoll and W. Weisweiler, 'Effect of vanadia and tungsten loadings on the physical and chemical characterization of $V_{2}O_{5}-WO_{3}/TiO_{2}$ catalysts', J. Mol. Catal. A: Chem. 208 (2004) 257 https://doi.org/10.1016/j.molcata.2003.07.016