Toward development of single-atom ceramic catalysts for selective catalytic reduction of NO with NH3

Insertion of transition metal species into crystalline alumina at low temperatures is proposed to achieve the dispersion of these species at atomic level paired with exceptional textural properties. Precisely, MeAl2O4/gamma-Al2O3 (Me = Mn, Fe, Co, Ni, and/or Cu) nanostructured ceramic catalysts were fabricated with ultra large mesopores (16-30 nm), and high specific surface area (180-290 m(2) g(-1)) and pore volume (1.1-1.6 cm(3) g(-1)). These ceramics were applied as efficient catalysts for the selective catalytic reduction (SCR) of NO with NH3, and their selectivity was discussed in terms of N2O formation, an undesirable byproduct. The catalysts containing Fe, Cu, or Mn showed the highest activities, however, within different temperature ranges. Further tuning of the catalytic activity and selectivity was achieved by creating ceramic catalysts with mixed compositions, e.g., CuFe and MnFe. Upon insertion of the transition metal species into crystalline structure of alumina to maximize atom efficiency, the N2O formation profile did not change significantly for all metal aluminates except MnAl2O4, indicating that these catalysts are suitable for SCR and selectively promote the reduction of NO.