Development of highly active three-dimensional cross-linked structural manganese-titanium composite oxides for NOx abatement: Insight into the resistance to sulfur and alkali metal poisoning mechanism

The industrial application of manganese composite oxides catalysts for NOx abatement by NH3-SCR is still significantly constrained by its poor resistance to sulfur and alkali metals. Herein, novelty mesoporous manganese-titanium composite oxides denitrification catalysts with three-dimensional structure are constructed by a distinctive solvents-free self-assembling strategy, which possess outstanding sulfur and alkali poisoning tolerance. The development of the hierarchical cross-linked structure with a large specific surface area is favorable for enhancing the synergy between Mn and Ti, exposing more active sites, and dispersing the poisoning species. The in-situ DRIFTS results reveal that SO2 seldom reacts with Mn active sites and hardly suppresses the ammonia adsorption and activation on the H-TiMn(0.5) catalyst surface benefiting from its abundant acidic sites. The redox centers and acidic sites of alkali-poisoned H-TiMn(0.5) could be well preserved owing to the well-dispersion of alkali metals and the existence of –OH groups as sacrificial sites, enabling its rapid reaction to follow the Eley-Rideal pathway. This work presents a new perspective on high-efficiency denitrification catalysts with exceptional tolerance to sulfur and alkali.