Mixed oxides supported low-nickel formulations for the direct amination of aliphatic alcohols with ammonia

Abstract

Abstract The present study focuses on the selective synthesis of primary amines from aliphatic alcohols and ammonia using alumina-ceria supported nickel formulations based on very low nickel loading (≤2 wt%) and without any additive or external H 2 supply. The effect of the catalyst preparation methods and modes of nickel impregnation were studied in detail and comprehensively characterized. The best formulation afforded 80% n -octanol conversion with 78% selectivity to n -octylamine at optimized reaction conditions, which were far better than control catalysts and benchmark Ni-alumina formulations relying on high Ni loadings. The enhanced activities of the alumina-ceria supported nickel catalysts was attributed to three combined effects: (1) a higher reducibility of surface nickel oxide species, (2) the genesis of very small and homogeneously distributed nickel nanoparticles (2–3 nm), and (3) a strong decline in the formation of nickel aluminates. Furthermore, unlike benchmark Ni catalysts, these formulations afforded a higher resistance to leaching.