Controllable preparation of Ni-CeO2 nanoparticles anchored on Al-Mg oxide spheres (AMO) by hydrophobic driving mechanism for dehydrogenative homo-coupling of pyridines

Abstract In this study, we synthesized a series of Ni-based catalysts with different CeO2 contents (0, 1, 2, 5 and 10 wt.%) anchoring on the Al-Mg oxide spheres (AMO) with three-dimensional hollow flower-like structure. The triethoxyoctylsilane (TEOOS) and polyvinylpyrrolidone (PVP) were selected as effective modified reagents to introduce hydrophobic functionality on the surface of AMO and Ni-CeO2 nanoparticles, respectively, for controllable anchoring Ni-CeO2 nanoparticles on AMO by hydrophobic interaction driving mechanism. The effects of CeO2 content on the texture, dispersion of Ni species, the reducibility of Ni2+, surface electronic states and acidity were investigated in detail. The Ni-5CeO2/AMO was found to achieve the highest 2,2′-bipyridine selectivity of 90.6% and maximum turnover number (TON) of 8611, specifically. Moreover, the Ni-5CeO2/AMO exhibits superior stability, maintaining 89% of 2,2′-bipyridine yield after 6 runs, due to the mitigated nickel leaching and promotion of the desorption of 2,2′-bipyridine. Furthermore, with the help of DFT calculations, a possible reaction mechanism was discussed and illustrated.