Abstract
The efficient strategy for enhancing the H2O/SO2 resistance is to maximize the exposure of catalytic sites that are less susceptible to sulfite/sulfate species, competitive adsorption and sulfation. Herein, the porous Fe2O3-WO3-Al2O3 (3D-FeWAl) catalysts with 3D spherical chrysanthemum-like shape structure were prepared by a double template method to reveal the structure-composition-H2O/SO2 resistance relationship of 3D-FeWAl materials for the NH3-SCR reaction with H2O + SO2. The water and sulfur resistance mechanism for NH3-SCR reaction over the 3D spherical daisy-like porous 3D-FeWAl catalyst was revealed. Results demonstrated that the 3D-FeWAl15 catalysts exhibited the excellent SCR activity and SO2/H2O-tolerant, achieving above 90 % NO conversion at 250–450 °C. Al2O3 was introduced to increase medium and strong acidic sites, providing more oxygen vacancies and Fe3+-Ov-W5+ interfacial sites. Importantly, the unique spherical chrysanthemum-like shape structure, which greatly maximized the exposure of catalytic sites, facilitated mass transfer reaction sites of reactants, and enhanced sufficiently dispersed active components, protecting the active molecules from sulfation. Besides, the rich 3D hierarchical porous system effectively promotes NH4HSO4 decomposition and weak SO2 adsorption. The formation of an abundant hydroxyl (–OH) group from the water molecules (H2O) at highly exposed catalytic sites results in the creation of a greater number of acidic sites for ammonia (NH3) adsorption, thus maintaining the high-efficiency NH3-SCR reaction. This study provides insight into the rational design of high-efficiency catalysts with good H2O/SO2 resistance.
Published Version
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