Diamine‐Assistant Synthesis of Cu@MFI Catalysts for Ethanol Dehydrogenation

Encapsulation of metal particles into zeolites is an attractive strategy for stabilizing metal species. Nevertheless, most metal cations tend to precipitate under basic and hydrothermal conditions without the use of effective anchoring agents. Herein, low-cost diamines of ethylenediamine and propanediamine were selected as effective chelators, which stabilized the Cu species under basic conditions and then anchored Cu species into the framework of MFI (silicate-1) during the hydrothermal process. The obtained Cu@MFI-R catalyst showed >96% ethanol conversion and 98% acetaldehyde selectivity in the 300 h time on stream, demonstrating superior advantages over the impregnation method prepared Cu/MFI catalysts. Characterization of Cu@MFI-R catalysts revealed that Cu nanoparticles were fixed in the framework of MFI, producing abundant Cu+ species for ethanol conversion. Additionally, the spatial confinement effects inhibited the Cu+ reduction and aggregations, affording a high catalyst stability. Differently, over Cu/MFI catalysts, the unconfined Cu+ species were prone to be reduced into Cu0 during the reaction, resulting in the Cu particles aggregation and activity depression.