Cavity size dependent SO2 resistance for NH3-SCR of hollow structured CeO2-TiO2 catalysts

CeO2-TiO2 hollow spheres with distinct cavity sizes of ca. 500 nm and 5 μm were prepared from carbon spheres and hybrid Ce–C sphere templates, respectively. After 40 h of successive operation in SO2-containing gas stream for the NH3-SCR reaction, the catalyst with large cavity showed only 4.7% activity loss, while that with small cavity exhibited sharp decrease (ca. 72.6%) in its deNOx activity. Results of physicochemical characterizations manifested that accelerated decomposition of NH4HSO4 on the CeO2-TiO2 catalyst with larger cavity size is likely largely responsible for the improved SO2 resistance of catalyst activity loss.