The effects of CeO 2 on catalytic activity of CeO 2 -TiO 2 for the selective catalytic reduction (SCR) of NO x were investigated in terms of structural, morphological, and physico-chemical analyseis. CeO 2 -TiO 2 catalysts were synthesized with three different additions, 10, 20, and 30 wt% of CeO 2 , by the sol-gel method. The XRD peaks of all specimens were assigned to a TiO 2 phase (anatase) and the peaks became broader with the addition of CeO 2 because it was dispersed as an amorphous phase on the surface of TiO 2 particles. The specific surface area of TiO 2 increased with the addition of CeO 2 from 60.6306 m 2 /g to 116.2791 m 2 /g due to suppression of TiO 2 grain growth by CeO 2 . The 30 wt% CeO 2 -TiO 2 catalyst, having the strongest catalytic acid sites (BrΦnsted and Lewis), showed the highest NO x conversion efficiency of 98 % at 300 o C among the specimens. It was considered that CeO 2 contributes to the improvement of the NO x conversion of CeO 2 -TiO 2 catalyst by increasing specific surface area and catalytic acid sites.
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