Component synergistic catalysis of Ce-Sn-W-Ba-O_x/TiO₂ in selective catalytic reduction of NO with ammonia

The component synergistic catalysis of the Ce-Sn-W-Ba-O_x/TiO₂ in selective catalytic reduction of NO (in the presence/absence of H₂O and SO₂) was investigated. Results verified that CeO₂ was an essential primary active component, and WO₃, SnO₂ and BaO were essential cocatalyst. TiO₂ provided enough acid sites, CeO₂ enhanced redox properties, weakened acid strength and increased chemisorbed oxygen concentration, which was beneficial to accelerate the activation and desorption of NH₃. SnO₂ increased chemisorbed oxygen concentration, enhanced redox properties and improved activation rate of NH₃. WO₃ increased acid amount and BaO enhanced the anti-influences to water vapor and SO₂. Their synergistic effects made Ce-Sn-W-Ba-O_x/TiO₂ exhibit excellent catalytic performance for NH₃-SCR, reaching the highest value about 100% at 350 °C in presence of H₂O and SO₂. Moreover, in situ DRIFTS study showed that the reaction followed L-H mechanism at high temperature and tended to simultaneously follow E-R and L-H mechanisms at low temperature.