Photothermal-Enhanced Anti-SO2 Performance of a MoWOx/CeO2 Catalyst in Low-Temperature NH3-SCR

Cerium-based catalysts for the selective catalytic reduction of NOx with ammonia (NH3-SCR) face significant challenges in practical applications, particularly their poor low-temperature activity and susceptibility to SO2 poisoning. In this study, photothermal catalysis was innovatively applied to the NH3-SCR reaction over MoWOx/CeO2 catalysts, achieving remarkable improvements in the low-temperature performance and SO2 resistance. Under photothermal conditions, the catalyst maintained NOx conversion above 90% at 200 °C, even in the presence of 250 ppm of SO2. Comprehensive characterization revealed that light irradiation significantly enhanced the formation of oxygen vacancies on the catalyst surface and weakened NO adsorption, indicating that the NH3-SCR reaction follows the Eley–Rideal mechanism, which contributes to its excellent low-temperature activity. Moreover, photothermal conditions reduced the chemical adsorption intensity of SO2, effectively inhibiting the formation of ammonium sulfate. Density functional theory calculations further demonstrated that the narrow band gap of MoWOx promotes electron transfer from the O 2p orbital to the Ce 4f orbital at the Ce–O–Mo(W) interface under light, leading to electron enrichment at active sites and suppression of SO2 oxidation. This work not only provides a novel strategy for enhancing the NH3-SCR performance but also represents a groundbreaking advancement in the design of highly efficient, SO2-resistant catalysts for low-temperature applications.