Highly active MnOx supported on the MgAlOx oxides derived from LDHs for low temperature NH3-SCR

• MgAlO x oxides derived from LDHs was used as support for high active NH 3 -SCR catalyst. • The highly dispersed MnO x on support were prepared by incipient wetness impregnation. • The novel catalysts exhibited superior low-temperature activity and N 2 selectivity. • The optimal catalyst MnA/MgAlO x -800 showed remarkable resistance to H 2 O. A series of novel highly dispersed MnO x on the MgAlO x support derived from layered double hydroxides (LDHs) were successfully prepared by incipient wetness impregnation method for low-temperature selective catalytic reduction of NO x with ammonia (NH 3 -SCR). The physicochemical properties and the catalytic performance of the prepared samples with different Mn precursor salt (acetate, nitrate and sulfate) and varying calcination temperatures of MgAlO x support were systematically investigated. The optimal catalyst, MgAlO x calcined at 800 °C with impregnating manganese acetate (denoted as MnA/MgAlO x -800), exhibited superior denitration performance, with NO x conversion over 80 % in the temperature range of 100–300 °C as well as remarkable resistance against H 2 O. The proper supports MgAlO x not only provided large specific area for the dispersion of the Mn, but also supplied more adsorption sites for reactant molecules. It was also found that the interaction between Mn species and MgAlO x support induced the higher concentration of Mn 4+ and chemisorbed oxygen species. As suggested from in situ DRIFTs analysis, Lewis acid sites promoted the adsorption and activation of NH 3 , which facilitated the NH 3 -SCR reaction to proceed. Furthermore, E-R mechanism was proposed in the SCR reaction, evidenced by in situ DRIFTS study.