The reactivity of ternary V2O5-WO3/TiO2 De-NOx catalysts is investigat
ed by transient and steady-state techniques, and results have been com
pared with those obtained over binary V2O5/TiO2 samples having the sam
e V2O5 loading. The results indicate that the reactivity of the ternar
y catalysts in the SCR reaction is higher than that of the vanadia-tit
ania samples, and that at low temperatures the SCR reaction occurs via
a redox mechanism that involves at first the participation of the cat
alyst lattice oxygen and then the reoxidation of the reduced sites by
gas-phase oxygen. Accordingly, the higher reactivity of the ternary ca
talysts has been related to their superior redox properties.