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

Cerium-based catalysts for the selective catalytic reduction of NO_x 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 MoWO_x/CeO₂ catalysts, achieving remarkable improvements in the low-temperature performance and SO₂ resistance. Under photothermal conditions, the catalyst maintained NO_x 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 MoWO_x 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.