NiFeNa/Al₂O₃ Acid–Base Bifunctional Catalysts for Hexamethylenediamine Synthesis via Adiponitrile Hydrogenation under Base-Free Conditions

Ni has been extensively employed in catalytic applications owing to its cost-effectiveness, natural abundance, and versatile catalytic properties. However, industrial implementation typically requires alkaline additives to control product selectivity, consequently complicating downstream separation and purification processes. This study reported the successful development of a NiFeNa/Al2O3 acid–base bifunctional catalyst for efficient hexamethylenediamine production through adiponitrile (ADN) hydrogenation under base-free conditions. Characterization data demonstrate that the NiFeNa/Al2O3 catalyst with optimal Na loading exhibits superior catalytic activity, which can be attributed to its well-balanced acid–base synergy. Furthermore, we established a plausible reaction mechanism for ADN hydrogenation mediated by acid–base cooperative effects, elucidating the relationship between acid–base properties and product selectivity. These results offer valuable insights for designing acid–base bifunctional catalysts and demonstrate the potential of Ni-based catalysts for base-free applications.