Surface Pd-rich PdAg nanowires as highly efficient catalysts for dehydrogenation of formic acid and subsequent hydrogenation of adiponitrile

The demand for nylon-66 has sharply increased in industry because of its high mechanical strength, high rigidity, and excellent stability. The deep hydrogenation of adiponitrile (ADN) to 1,6-hexanediamine (HDA) is considered as a crucial step to produce nylon-66 in industry. Herein, we report a diffusion strategy to prepare surface Pd-rich PdAg nanowires (NWs) via a seed-mediated growth in polyol solution for efficient dehydrogenation catalysis of formic acid (FA) and subsequent hydrogenation of ADN by using FA as an in situ hydrogen source. The composition of surface Pd-rich PdAg NWs could be easily tuned by controlling the amounts of the precursors. And the surface Pd-rich Pd₅Ag₅ NWs exhibit the highest activity for dehydrogenation catalysis of FA with an initial TOF of 1600 h^-1 and a highly efficient hydrogenation of ADN to HDA with 99% selectivity and 99% conversion at 50 °C. Their enhanced catalytic performance could be attributed to the Pd-rich surface of the NWs and more efficient electron transfer from Ag to Pd. This work demonstrates a new way to prepare surface Pd-rich Pd₅Ag₅ NWs for deeply hydrogenating ADN to HDA with FA as an in situ hydrogen source.