Dy-Modified Mn/TiO₂ Catalyst Used for the Selective Catalytic Reduction of NO in Ammonia at Low Temperatures

A novel Mn/TiO₂ catalyst, prepared through modification with the rare-earth metal Dy, has been employed for low-temperature selective catalytic reduction (SCR) denitrification. Anatase TiO₂, with its large specific surface area, serves as the carrier. The active component MnO_x on the TiO₂ carrier is modified using Dy. Dy_xMn/TiO₂, prepared via the impregnation method, exhibited remarkable catalytic performance in the SCR of NO with NH₃ as the reducing agent at low temperatures. Experiments and characterization revealed that the introduction of a suitable amount of the rare-earth metal Dy can effectively enhance the catalyst's specific surface area and the gas-solid contact area in catalytic reactions. It also significantly increases the concentration of Mn⁴⁺, chemisorbed oxygen, and weak acid sites on the catalyst surface. This leads to a notable improvement in the reduction performance of the DyMn/TiO₂ catalyst, ultimately contributing to the improvement of the NH₃-SCR denitrification performance at low temperatures. At 100 °C and a space velocity of 24,000 h^-1, the Dy_0.1Mn/TiO₂ catalyst can achieve a 98% conversion rate of NO_x. Furthermore, its active temperature point decreases by 60 °C after the modification, highlighting exceptional catalytic efficacy at low temperatures. By doubling the space velocity, the NO_x conversion rate of the catalyst can still reach 96% at 130 °C, indicating significant operational flexibility. The selectivity of N₂ remained stable at over 95% before reaching 240 °C.