Synergistic effects of the bimetallic Ni–Fe systems and their application in the reductive amination of polyether polyols

Abstract

We report the synthesis of xNi–yFe/γ-Al₂O₃ catalysts which were applied to the reductive amination of polypropylene glycol (PPG) for the preparation of polyether amine (PEA). The catalysts were characterized by N₂-sorption, X-ray diffraction, H₂-temperature programmed reduction, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy to reveal the synergistic effect of the bimetallic Ni–Fe-loaded catalysts. It was found that in the reductive amination of PPG to PEA, the conversion and product selectivity of the reaction were closely related to the types of active centers of the catalyst. In particular, the surface Ni⁰ content increased by adding Fe as a promoter, with a maximum Ni⁰ content on the 15Ni–7.5Fe/Al₂O₃ catalyst, which also led to the highest conversion rate (>99%). In addition, no deactivation was observed after three cycles of reaction carried out by the catalyst.