VxMn(4 − x)Mo3Ce3/Ti catalysts for selective catalytic reduction of NO by NH3.

A series of vanadium based catalysts (V x Mn(4− x)Mo3Ce3/Ti) with different vanadium (x wt.%) and manganese ((4− x) wt.%) contents have been prepared by the wet impregnation method and investigated for selective catalytic reduction (SCR) of NO x by NH 3 in the presence of 8 vol.% H 2 O and 500 ppmV SO 2. The physicochemical characteristics of the catalysts were thoroughly characterized. The SCR of NO x by NH 3 (NH 3 -SCR) activity, especially the low-temperature activity, significantly increased with increasing V 2 O 5 content in the catalyst until the V 2 O 5 content reached 1.5 wt.%, which corresponds well with the redox properties of the catalyst. All of the metal oxides were well dispersed and strongly interacted with each other on the catalyst surface. V mainly exists in the V5+ state in the catalysts. The strong synergistic effect between the vanadium and cerium species led to formation of more Ce3+ species, and that between the vanadium and manganese species contributed to formation of more manganese species with low valences. All of the catalysts exhibited strong acidity, while the redox properties determined the NH 3 -SCR activity, especially the low-temperature activity. H 2 O and SO 2 had severe inhibiting effects on the activity of V1.5Mn2.5Mo3Ce3/Ti. However, good H 2 O and SO 2 resistance and high NO x conversion by V1.5Mn2.5Mo3Ce3/Ti could be achieved in the presence of SO 2 and almost no decline was observed in a long-term test at 275°C for 168 hr in the presence of SO 2 and H 2 O, which can be attributed to the sulfate species formed on the catalyst surface. Unlabelled Image [ABSTRACT FROM AUTHOR]