Improved N Selectivity of MnO Catalysts for NO Reduction by Engineering Bridged Mn Sites.

Mn-based catalysts are promising for selective catalytic reduction (SCR) of NO with NH at low temperatures due to their excellent redox capacity. However, the N selectivity of Mn-based catalysts is an urgent problem for practical application owing to excessive oxidizability. To solve this issue, we report a Mn-based catalyst using amorphous ZrTiO as the support (Mn/ZrTi-A) with both excellent low-temperature NO conversion and N selectivity. It is found that the amorphous structure of ZrTiO modulates the metal-support interaction for anchoring the highly dispersed active MnO species and constructs a uniquely bridged Mn bonded with the support through oxygen linked to Ti and Zr, respectively, which regulates the optimal oxidizability of the MnO species. As a result, Mn/ZrTi-A is not conducive to the formation of ammonium nitrate that readily decomposes to NO, thus further increasing N selectivity. This work investigates the role of an amorphous support in promoting the N selectivity of a manganese-based catalyst and sheds light on the design of efficient low-temperature deNO catalysts.