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

A novel Mn/TiO catalyst, prepared through modification with the rare-earth metal Dy, has been employed for low-temperature selective catalytic reduction (SCR) denitrification. Anatase TiO, with its large specific surface area, serves as the carrier. The active component MnO on the TiO carrier is modified using Dy. DyMn/TiO, prepared via the impregnation method, exhibited remarkable catalytic performance in the SCR of NO with NH 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 Mn, chemisorbed oxygen, and weak acid sites on the catalyst surface. This leads to a notable improvement in the reduction performance of the DyMn/TiO catalyst, ultimately contributing to the improvement of the NH-SCR denitrification performance at low temperatures. At 100 °C and a space velocity of 24,000 h, the DyMn/TiO catalyst can achieve a 98% conversion rate of NO. 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 conversion rate of the catalyst can still reach 96% at 130 °C, indicating significant operational flexibility. The selectivity of N remained stable at over 95% before reaching 240 °C.