Speeding up low-temperature SCR with reactants-coupling dual catalytic sites

Selective catalytic reduction (SCR) of NOx with NH3 over V2O5-based catalysts has been widely used to control NOx emissions from power plants, but its application is largely limited in other industrial boilers because of insufficient catalytic efficiency at low temperatures. Here we resolve this problem by mechanistically designing a highly active Ce-W/TiO2 catalyst with reactants-coupling dual catalytic sites. The results demonstrate that W and Ce are highly dispersed on the surfaces of Ce-W/TiO2 to form dual catalytic sites, which act as acid-base pairs favorable for NH3 and NO adsorption, respectively, thereby allowing the reaction of adsorbed NH3 on the W site with oxidized NO species (NO3-) adsorbed on the adjacent Ce site to proceed along a low-activation-energy pathway via Langmuir-Hinshelwood mechanism. Compared with Ce/TiO2, a W-Ce synergy gives rise to more abundant Ce3+ on Ce-W/TiO2, which facilitates the activation of O-2 during SCR process, thus improving the low temperature SCR performance. Therefore, the design of the dual catalytic sites based on the properties of reactants provides an alternative approach to developing highly active SCR catalysts.

Automated summary

This study tackles the issue of insufficient catalytic efficiency of SCR at low temperatures by designing a Ce-W/TiO2 catalyst with reactants-coupling dual catalytic sites. The results reveal that W and Ce are highly dispersed to form dual catalytic sites, which enhance NH3 and NO adsorption and facilitate the reaction between them. The Ce-W synergy boosts the SCR performance at low temperatures by promoting the activation of O-2.