Oxygen Vacancy-Mediated H 2 O Dissociation Enhances H 2 O Resistance of WO 3 /FeCuSSZ-13 for Low-Temperature Selective Catalytic Reduction of NO x

Selective catalytic reduction of nitrogen oxides (NO x ) by ammonia (NH 3 –SCR) has been the predominant aftertreatment technology for both stationary and mobile sources. Despite its widespread use, NH 3 –SCR catalysts still suffer from the persistent issue of low-temperature H 2 O-induced poisoning. Herein, we present an approach to mitigate H 2 O inhibition, transforming this challenge into an advantage by reversing its detrimental effects on low-temperature NH 3 –SCR catalysts. We demonstrate that the strong interface interaction between WO 3 and FeCu-SSZ-13 in the designed WO 3 /FeCu-SSZ-13 selectively induces the generation of abundant oxygen vacancies in the WO 3 component. These oxygen vacancies effectively dissociate H 2 O to produce hydroxyl groups and protons (H + ), thereby facilitating the formation of the key reaction intermediates HONO and NH 4 NO 2 during the low-temperature NH 3 –SCR process. Under conditions of 165 °C and 20 vol % H 2 O, the NO conversion over WO 3 /FeCu-SSZ-13 is approximately 20% higher than that over the pristine FeCu-SSZ-13. Furthermore, this work proposes a dual-path synergistic catalytic mechanism in which both hydroxyl species and H + derived from H 2 O dissociation collectively accelerate the reaction. This breakthrough provides a solid theoretical foundation for designing a highly efficient FeCu-SSZ-13 catalyst with low-temperature H 2 O resistance, addressing a key limitation in current catalyst development.