Lewis and Brønsted Acid Synergistic Catalysis for Efficient Synthesis of Hydroxylamine over Heteroatom Zeolites

Environmental and efficient synthesis of NH₂OH is challenging. Herein, we have provided a route for efficient NH₂OH formation by NH₃ oxidation via the synergistic catalysis of Lewis acid sites of the framework Ti (Ti LAS) and Brønsted acid sites of the framework Al (Al BAS) in Ti-Al-MOR zeolites. Ti LAS was the active center for formation of transition-state NH₂OH, while Al BAS could provide the proton H to convert transition-state NH₂OH absorbed on Ti LAS to a [NH₃OH]⁺ species. Protonation effect would not only promote the catalytic cycle process resulting from accelerating the desorption of transition-state NH₂OH, but also improve the stability of NH₂OH, being less prone to oxidative decomposition. In this work, we presented the synergistic catalysis between LAS and BAS over Ti-containing heteroatom zeolites to accelerate the catalytic cycle, which provided an environmental and efficient method for NH₂OH formation.