Niobium oxide confined by ceria nanotubes as a novel SCR catalyst with excellent resistance to potassium, phosphorus, and lead

In this study, a novel niobia-doped ceria nanotubes material (Nb-CeNTs) is synthesized and used as deNO(x) catalyst. For comparison, a nanoparticle sample is also obtained by doping CeO2 nanoparticles with niobia (Nb-CeO2(N)). The Nb-CeNTs catalyst shows superior NOx conversion and resistance to alkali metals, phosphorus, and lead than Nb-CeO2(N) for selective catalytic reduction (SCR) by NH3. After subjected to a range of characterization techniques, it is found that the enhanced resistance is mainly attributed to the special nanotubular structure of ceria nanotubes, smooth Nb5+/Nb4+ and Ce4+/Ce3+ redox cycles, superior redox capacity, and abundant surface Bronsted acidic sites. Moreover, the well-maintained nanotubular structure also accounts for the excellent resistance performance of the Nb-CeNTs catalyst. We foresee that the remarkable chemical properties and self-protection effect of the Nb-CeNTs catalyst may provide a novel approach for the design and synthesis of SCR catalysts to improve the resistance to different kinds of poisons, such as alkali/alkaline earth metals, phosphorus compounds, and heavy metals.