Anatase $TiO_2$에 $WO_3$ 및 $V_2O_5$ 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.
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.
