Na-Modified Al2O3-Supported Nickel-Based Catalysts for Liquid-Phase Hydrogenation of Adiponitrile: Effect of Acidity

Catalysts for the hydrogenation of adiponitrile (ADN) have been extensively studied, but achieving high selectivity of hexamethylenediamine (HMDA) in the absence of additional alkali inhibitors still poses many challenges. Herein, we fabricated nickel-based catalysts modified with Na additives for the liquid-phase hydrogenation of ADN in a fixed-bed reactor. The results showed that suitable weak acid sites are more conducive to enhancing the selectivity for HMDA, while stronger acid sites tend to promote the formation of higher amines. Moreover, the introduction of an appropriate amount of Na additive facilitates the dispersion of nickel, increasing the content of Ni-0 species. Its electron-donating capacity to nickel aids in hydrogen adsorption and dissociation, thereby enhancing hydrogenation activity and favoring the selectivity for HMDA. Under optimal conditions of 120 degrees C and 4 MPa, improved catalytic performance with 100% ADN conversion and 82.07% HMDA selectivity were achieved over the Ni-0.15Na/Al2O3 catalyst.