Ammonia-free selective catalytic reduction of NO by coal-based activated carbon supported Cu-Mn oxides at low temperature

Abstract

Selective catalytic reduction of ammonia is the most widely technology for removing NOx, but there were serious ammonia leakage and high temperature reaction. To overcome these limitations, a series of Cu and Mn metals supported on coal-based activated carbon (CuxMny/CAC) were synthesized, for ammonia-free catalytic reduction of NO at low temperature. The results demonstrated that Cu and/or Mn catalysts significantly improved low-temperature SCR performance and char-NO reaction selectivity when combined with CAC. In particular, Cu6Mn4/CAC showed excellent NO removal rate (100 %) and higher char-NO selectively (111.21 mg/g) at 290 ℃ under O2-rich condition. Characterization analyses revealed that Cu6Mn4/CAC had a larger BET surface area and preferable pore structure, and the synergistic effect mainly came from the redox cycle between CuOx and MnOy, as well as the interaction between Cu-Mn oxides and the CAC support. Cu-Mn metals promote the adsorption of NO and O2 in the char-NO process, leading to the generation of abundant surface adsorption oxygen species (O2-, O22-, and O-) and C(O) complex, which facilitated the char-NO reaction. Therefore, a mechanism for ammoniac-free selective catalytic reduction of NO by Cu6Mn4/CAC was proposed. These finding provide new insights for developing low-temperature ammonia-free denitrification technology and improving high-value utilization of coal resources.