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

This paper reports the use of beta-cyclodextrin as a pre-shaping agent for the preparation of low-metal xNi-yPd/Al2O3 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 beta-cyclodextrin was pre-adsorbed on gamma-Al2O3 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 degrees C for 4 h, which places it among the most active and selective Ni catalysts reported in the literature. (C) 2018 Elsevier Inc. All rights reserved.