Synergistic roles of platinum nanoparticles and sodium ions within beta zeolites in N-alkylation of amines with aromatic alcohols

N-alkylation of amines with alcohols is a promising green route for the synthesis of N-alkylamines, but the designation of highly active and stable heterogeneous catalysts remains one challenge. In this work, we initiated the application of zeolite-encapsulated noble metal nanoparticles (NPs) in the N-alkylation of amines with aromatic alcohols. Platinum (Pt) NPs were directly confined into the framework of BEA zeolite with tunable Si/Al molar ratios and Na⁺ contents. The champion catalyst afforded the extremely high turnover number (TON) of 6,176 and turnover frequency (TOF) of 3,390 h⁻¹ plus stable recyclability and broad substrate compatibility. The Na ions modulated the electronic state of Pt NPs to reach a moderate Pt-H strength, which well-balanced the two crucial steps of dehydrogenation and H-transfer and accounted for the high catalytic performance. The encapsulation of zeolites provided spatial satisfaction for the synergy effect above and enhanced the stabilization of Pt NPs. [Figure not available: see fulltext.]