Highly Active and Air-Stable Iron Phosphide Catalyst for Reductive Amination of Carbonyl Compounds Enabled by Metal–Support Synergy

Iron has long been recognized as an ideal catalytic material for sustainable chemistry. However, conventional iron catalysts employed in liquid-phase hydrogenation reactions suffer from poor activity and air instability, severely restricting their wide applicability in practical use. Herein, we present the development of highly active and air-stable iron phosphide nanocrystal immobilized on zirconia (Fe₂P NC/ZrO₂) for the reductive amination of aldehydes and ketones. The Fe₂P NC/ZrO₂ catalyst demonstrated broad substrate applicability, high recyclability, and scalability in both gram-scale and continuous-flow processes. This catalyst leverages the synergistic metal-support effect of Fe₂P NCs and ZrO₂ support, leading to activity 313 times higher than that of conventional iron nanoparticle catalysts. In-depth mechanistic studies elucidated that the distinctive interplay between Fe₂P and ZrO₂ significantly accelerates ammonolysis of Schiff bases, a key step for boosting reaction efficiency. This study sets a new benchmark for iron-based catalysis, offering a robust alternative to precious metals, thereby contributing significantly to sustainable chemical manufacturing and green organic synthesis.