Yihang Dong,Zhaoyang Liu,Lipeng Pang,Ye Han,Shuyu Yao,Xiangnan Wang
{(Y 2 O 3 ) 0·08 (ZrO 2 ) 0.92 } 1- x (CeO 2 ) x (0 ≤ x ≤ 0.6) is synthesized by co-precipitation method. Thermal analysis, phase structure, lattice constant , micro-morphology, elements distribution, density, open porosity and electrical conductivity are measured by TG, DSC , XRD , GSAS, SEM , EDS, Archimedes method and EIS respectively, and the influence of CeO 2 content on the above properties are investigated. TG-DSC results show that the weight loss of the sample is mainly due to the decomposition of the initial powder, forming a solid solution above ~600 °C. XRD results show that {(Y 2 O 3 ) 0·08 (ZrO 2 ) 0.92 } 1- x (CeO 2 ) x (0 ≤ x ≤ 0.6) is a cubic solid solution, and the lattice parameters and volume increase with the increase of CeO 2 content. SEM results show that YZC is a dense sintered body. Density and open porosity of YZC sample are ~4.5 g cm −3 and ~0.12, respectively. The electrical conductivity results show that the conductivity of {(Y 2 O 3 ) 0·08 (ZrO 2 ) 0.92 } 1- x (CeO 2 ) x (0 ≤ x ≤ 0.2) is equivalent, and then the conductivity decreases due to defect association with the increase of CeO 2 content.
In this study, we synthesized a series of Ni-based catalysts with different CeO 2 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-CeO 2 nanoparticles, respectively, for controllable anchoring Ni-CeO 2 nanoparticles on AMO by hydrophobic interaction driving mechanism. The effects of CeO 2 content on the texture, dispersion of Ni species, the reducibility of Ni 2+ , surface electronic states and acidity were investigated in detail. The Ni-5CeO 2 /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-5CeO 2 /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.
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