Cyclodextrin-assisted low-metal Ni-Pd/Al2O3 bimetallic catalysts for the direct amination of aliphatic alcohols.

Graphical abstract Highlights • CD-assisted Ni-Pd bimetallic catalysts were prepared by different impregnation routes. • The best method involves the pre-adsorption of CD on Al 2 O 3 before adding metal salts. • High dispersion of surface Ni nanoparticles (5–6 nm) along with surface Pd enrichment. • A 71% yield to n-octylamine was achieved in the reaction of 1-octanol with ammonia. Abstract This paper reports the use of β-cyclodextrin as a pre-shaping agent for the preparation of low-metal xNi-yPd/Al 2 O 3 catalysts (x = 2, 5 wt% and y = 0.2, 0.5, 1.0 wt%) targeting the direct amination of 1-octanol with ammonia. Six different preparation methods were used aiming at tuning the Ni-Pd interaction. The catalysts were finely characterized by XRD, H 2 -TPR, CO pulse chemisorption, STEM-EELS/EDS-SDD and XPS, while the elementary interaction between Ni-Pd-cyclodextrin was assessed by marrying ESI-MS experiments with DFT calculations. Among the different methods studied, the most outstanding effect was obtained when β-cyclodextrin was pre-adsorbed on γ-Al 2 O 3 before impregnating the Ni and Pd nitrate precursors. At such conditions, the best formulation (5Ni-0.5Pd/Al-CD_M4) afforded 90% conversion and 71% yield to 1-octylamine (TON = 93) in the amination of 1-octanol with ammonia at 160 °C for 4 h, which places it among the most active and selective Ni catalysts reported in the literature. [ABSTRACT FROM AUTHOR]