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 (NOx) by ammonia (NH3–SCR) has been the predominant aftertreatment technology for both stationary and mobile sources. Despite its widespread use, NH3–SCR catalysts still suffer from the persistent issue of low-temperature H2O-induced poisoning. Herein, we present an approach to mitigate H2O inhibition, transforming this challenge into an advantage by reversing its detrimental effects on low-temperature NH3–SCR catalysts. We demonstrate that the strong interface interaction between WO3 and FeCu-SSZ-13 in the designed WO3/FeCu-SSZ-13 selectively induces the generation of abundant oxygen vacancies in the WO3 component. These oxygen vacancies effectively dissociate H2O to produce hydroxyl groups and protons (H+), thereby facilitating the formation of the key reaction intermediates HONO and NH4NO2 during the low-temperature NH3–SCR process. Under conditions of 165 °C and 20 vol % H2O, the NO conversion over WO3/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 H2O dissociation collectively accelerate the reaction. This breakthrough provides a solid theoretical foundation for designing a highly efficient FeCu-SSZ-13 catalyst with low-temperature H2O resistance, addressing a key limitation in current catalyst development.