Synergistic effect of facet engineering and dual active sites in manganese cerium titanium mixed oxide nanotubes on boosting nitrogen oxide removal performance and resistance to sulfur dioxide and water poisoning.

In industrial flue gas containing SO2 and H2O, metal oxide catalysts undergo severe deactivation due to the deposition of (NH4)2SO4/NH4HSO4 and metal sulfates. Therefore, developing catalysts with satisfactory SO2 and H2O tolerance remains a major challenge. In this study, a hollow Mn0.05Ce0.05TiOx-T (MnCeTiOx-T) catalyst is constructed via an in situ co-growth method, achieving a morphological transition from nanoparticles to nanotubes, which enables precise regulation of microstructure and surface properties. Characterization results showed that the synergistic effect of the unique nanotube structure and dual active centers (Mn and Ce) significantly increases the specific surface area (339 m2∙g-1) and surface Brønsted acidity (Ti-OH), while simultaneously improving its redox properties, enabling the MnCeTiOx-T catalyst to achieve nearly 100% NO conversion within 180-390 °C and long-term stability. Experimental data and DFT calculations indicate that the (200) facet predominantly exposed on the nanotube morphology effectively suppresses the adsorption of H2O/SO2 and promotes the adsorption and activation of NH3, thereby enhancing the catalytic activity and poisoning resistance of MnCeTiOx-T. Moreover, in situ infrared spectroscopy shows that the nanotube structure not only promotes the formation of Brønsted acid sites but also significantly accelerates the SCR reaction rate, favoring the NH3-SCR process. In summary, this study proposes a design concept centered on dual regulation of morphology and the exposed facets to synergistically optimize specific surface area, surface acidity and redox properties, markedly enhancing SCR activity and anti-poisoning performance, and providing an effective strategy for developing H2O/SO2-tolerant NH3-SCR catalysts.