Binary copper-manganese based catalysts with urea for low-temperature selective catalytic reduction of NO: Performance, characterization and mechanism

Abstract

The NO emission reduction for low-temperature flue gas is still a serious challenge, low-temperature selective catalytic reduction with urea (LTU-SCR) is a new and promising approach for removing NO at low temperatures (50–100 °C), which can avert the ammonia escape of the conventional SCR method. In this work, a series of binary catalysts were prepared and used for LTU-SCR, the carrier and catalysts were characterized in detail by EA, BET, FESEM, EDS, XRD, XPS, AAS, TPD, FT-IR and TGA. The results of catalytic activity tests showed that the binary catalysts exhibited better performance than the unary catalysts. When the calcination temperature is 500 °C and the mass ratio of CuOx to MnOx is 5:5, the binary Cu-Mn/NUAC catalyst had the highest catalytic activity. Moreover, the performance of the binary catalyst increased with the increasing reaction temperature, and the binary Cu0.5Mn0.5/NUAC catalyst could achieve 100% NO conversion at 100 °C. Finally, based on the results of NO transient responses, characterization experiments and thermodynamic analyses, the NO conversion mechanism on the binary Cu0.5Mn0.5/NUAC catalyst was proposed and discussed systematically; the synergetic effect between copper and manganese on the binary catalyst was attributed to the electron transfer of Cu2+ + Mn2+ ⇌ Cu0 + Mn4+.