Dynamic Brønsted Acid Site Compensation Enables Water-Tolerant Low-Temperature NH3-SCR over Co-WO3/FeCu-SSZ-13

Water-induced deactivation of catalysts under low-temperature and high-humidity conditions remains a major challenge for the practical application of NH3-selective catalytic reduction (NH3-SCR) technology. Herein, a dynamic Brønsted acid site compensation strategy based on the heterolytic dissociation of H2O is proposed to improve the water tolerance of Cu-based chabazite catalysts. Following this strategy, a Co-WO3/FeCu-SSZ-13 catalyst was rationally designed. Co doping effectively modulates the d-band center of WO3, enabling heterolytic H2O dissociation and the in situ generation of hydroxyl groups that act as Brønsted acid sites, thereby significantly enhancing NH3 adsorption and activation. Simultaneously, preferential utilization of H2O for Brønsted acid site compensation mitigates its competitive occupation of the intrinsic metal active sites in FeCu-SSZ-13, preserving the NO oxidation pathway under high-humidity conditions. Therefore, this synergistic regulation of dynamic compensation of Brønsted acid sites and the release of active metal sites enables Co-WO3/FeCu-SSZ-13 to achieve a NOx conversion exceeding 90% at 165 °C in the presence of 20 vol % H2O. This work highlights the dual role of H2O in simultaneously regulating the acid and redox cycles, offering a general strategy for designing water-tolerant NH3-SCR catalyst.