Low-temperature direct decomposition of NO over Rh/NC-MnFe catalyst: activity, stability and mechanism

Abstract

As the ideal NO removal technology, the biggest challenge associated with the direct catalytic decomposition of NO is the development of highly active deNOx catalysts at low temperatures. Herein, a composite metal catalyst, Rh(0.2)/NC-MnFe, was prepared via impregnation for the low-temperature direct decomposition of NO, which exhibited 99.6% NO conversion and 63% N₂ selectivity at 150 °C, and nearly 100% NO conversion and 98% N₂ selectivity at 200 °C. The characterization results showed that the Rh(0.2)/NC-MnFe catalyst possessed a regular nanocage structure, good crystallinity, and suitable specific surface area. Its excellent low-temperature activity was attributed to the transfer of the dissociated O of NO from the Rh active site to the NC-MnFe support, which effectively inhibited the deactivation of Rh. The mechanism analysis indicated that NO adsorbed on the Rh(0.2)/NC-MnFe catalyst surface can generate NO₂⁻ and NO₃⁻, and then the adsorbed NO together with NO₃⁻ is converted to NO₂⁻ species accompanied by the release of N₂O. At last, NO₂⁻ is decomposed to N₂.