Preparation and characterization of monolith catalysts loaded with copper and manganese for lowtemperature NH₃-SCR

Mn-Ce-O/TiO₂ and Cu-Ce-O/TiO₂ phases were loaded onto the cordierite honeycomb ceramics using sol-gel method. A series of monolith catalysts with multilayer washcoat was prepared with different mass ratio of these two phases. The catalysts exhibit high activity at low temperatures and a wide temperature window for the selective catalytic reduction of NO with ammonia (NH₃-SCR). NO conversion was 95% at 250℃ with the inlet NO concentration of 1025mg/m³, and the gas hourly space velocity (GHSV) of 12600h^-1; the conversion of NO was above 80% in the temperature range of 200℃~300℃. The catalysts with multilayer washcoat performed much better in NH₃-SCR than the single-phase catalyst. The results from BET, XRD, XPS, TPR, and SEM suggested that the high activity of these catalysts can be attributed to the large surface area, high loading of amorphous active components, TiO₂ in the form of anatase, abundant surface cracks, and good redox capability of the multilayer structures.