A High-Performance Mn/TiO₂ Catalyst with a High Solid Content for Selective Catalytic Reduction of NO at...

Mn/TiO₂ catalysts with varying solid contents were innovatively prepared by the sol-gel method and were used for selective catalytic reduction of NO at low temperatures using NH₃ (NH₃-SCR) as the reducing agent. Surprisingly, it was found that as the solid content of the sol increased, the catalytic activity of the developed Mn/TiO₂ catalyst gradually increased, showing excellent catalytic performance. Notably, the Mn/TiO₂ (50%) catalyst demonstrates outstanding denitration performance, achieving a 96% NO conversion rate at 100 °C under a volume hourly space velocity (VHSV) of 24,000 h^-1, while maintaining high N₂ selectivity and stability. It was discovered that as the solid content increased, the catalyst's specific surface area (SSA), surface Mn⁴⁺ concentration, chemisorbed oxygen, chemisorption of NH₃, and catalytic reducibility all improved, thereby enhancing the catalytic efficiency of NH₃-SCR in degrading NO. Moreover, NH₃ at the Lewis acidic sites and NH⁴⁺ at the Bronsted acidic sites of the catalyst were capable of reacting with NO. Conversely, NO and NO₂ adsorbed on the catalyst, along with bidentate and monodentate nitrates, were unable to react with NH₃ at low temperatures. Consequently, the developed catalyst's low-temperature catalytic reaction mechanism aligns with the E-R mechanism.