Titania-Samarium-Manganese Composite Oxide for the Low-Temperature Selective Catalytic Reduction of NO with NH₃

A novel Ti-doped Sm-Mn mixed oxide (TiSmMnO) was first designed for the selective catalytic reduction (SCR) of NO with NH₃ at a low temperature. The TiSmMnO catalyst exhibited a superior catalytic performance, in which NO conversion higher than 80% and N₂ selectivity above 90% could be achieved in a wide-operating temperature window (60-225 °C). Specially, the catalyst also showed high durability against the large space velocity and excellent SO₂/H₂O resistance. Ti incorporation can efficiently inhibit MnO crystallization and tune the MnO phase during calcination at a high temperature. Subsequently, a high specific surface area as well as an increased amount of acid sites on the TiSmMnO catalysts were produced. Further, the reducibility of the Sm-doped MnO catalyst was modulated, facilitating NO oxidation and inhibiting NH₃ nonselective oxidation. Consequently, a superior SCR activity was achieved at a low temperature and the operating temperature window of the TiSmMnO catalyst was significantly widened. These findings may provide new insights into the reasonable design and development of the new non-vanadium catalysts with a high NH₃-SCR activity for industrial application.