Durable Copper Nanoparticles Confined in Dealuminated Beta Zeolite for Ethanol Dehydrogenation

Ethanol dehydrogenation to acetaldehyde represents an efficient pathway for ethanol valorization, capitalizing on the versatile utility of acetaldehyde as a key chemical intermediate and the inherently high atom economy of the dehydrogenation process. Copper (Cu)-based catalysts have demonstrated good catalytic activity in this reaction. However, their practical application is hampered by insufficient long-term stability, and the nature of the active sites under operational conditions remains ambiguous. Herein, we report a rationally designed Cu-Beta zeolite catalyst where isolated Cu atoms are anchored within silanol nests of a dealuminated beta (deAl-Beta) zeolite framework, forming well-defined {(≡SiO)2Cu(HO–Si≡)2} coordination sites. These isolated Cu species undergo spontaneous self-evolution during the reaction or H2 reduction conditions, transforming into confined Cu nanoparticles (2–3 nm) within the zeolite mesopores. The Cu nanoparticles are stabilized through zeolite confinement and interfacial Cu–O–Si interactions, exhibiting substantial catalytic performance with 85% conversion, 95% acetaldehyde selectivity, and stability exceeding 200 h (weight-time yield of ∼1570 mg gcat–1 h–1). Combining in situ XAS, in situ IR, and DFT calculations, we revealed a stepwise reaction mechanism involving sequential O–H and Cα–H bonds of ethanol, followed by H–H coupling, all facilitated by the confined Cu nanoparticles. This study highlights a strategy of in situ active site self-optimization through reaction-induced nanostructural confinement, establishing an effective paradigm for designing highly stable and efficient heterogeneous catalysts via dynamic structural evolution.