The influence of lattice oxygen in titania on selective catalytic reduction in the low temperature region

Vanadia/titania catalysts have various NOx conversion capabilities, which are dependent on the titania support, in selective catalytic reduction reactions with ammonia in the low temperature region. Because oxygen is an essential component in standard SCR reactions, the ability to provide lattice oxygen is an important factor dictating catalytic activity. lattice oxygen can be provided to the reactants from a vanadia support as well as from a titania support. When the lattice oxygen in vanadia is exhausted, lattice oxygen in titanium can be supplied to vanadium; through this transfer of lattice oxygen, the SCR reaction can continue to proceed and an oxygen bridge between vanadium and titanium can be formed. Therefore, titania supports containing O/Ti mole ratios varying from 1.8 to 2.0 without vanadium deposition were adequate as SCR catalysts. In this work, the dual site mechanism was modified; based on these findings a more detail mechanism is suggested. (C) 2010 Elsevier B.V. All rights reserved.