Modulating the Dispersion of Ce on CeO₂/TiO₂ Catalysts for Efficient NH₃–SCR of NO

CeO2–TiO2 catalysts have been intensively investigated for their promising application prospect in the selective catalytic reduction of NO by NH3 (NH3–SCR of NO). However, the optimal dispersion of CeO2 on CeO2–TiO2 catalysts is still controversial. In this work, using TiO(OH)2 and TiO2 as supports and different Ce precursors, TiO2-supported CeO2 with a controllable dispersion was prepared. It was uncovered that hydroxyl groups on TiO(OH)2 could facilitate the even dispersion of Ce (high dispersion, Ce/Ti–H), while the impregnation of cerium oxalate onto TiO2 would result in the generation of highly crystalline CeO2 (low dispersion, Ce/Ti-L), even with a low CeO2 loading of 5 wt %. When cerium nitrates were impregnated onto TiO2, slightly crystalline CeO2 (moderate dispersion, Ce/Ti-M) was successfully fabricated. The NH3–SCR activity on the prepared CeO2/TiO2 catalysts followed an order of Ce/Ti-M > Ce/Ti–H > Ce/Ti-L, suggesting that small CeO2 particles on TiO2 could better facilitate the proceeding of the NH3–SCR reaction. According to the results of the mechanism study, the superior redox capability of Ce/Ti-M enabled efficient activation of reactants, thus achieving the best NH3–SCR activity. This study provided a strategic framework for the design of high-performance catalysts by precisely engineering the dispersion of active species at the nanoscale.