A series of CeO2 supports with particular morphologies (nanorods, nanocubes, nanooctas, and nanoparticles) were successfully fabricated by controlling the parameters of the hydrothermal method. The obtained nano-CeO2 materials were utilized as the supports of the Ni-based CO2 methanation catalysts prepared by the incipient impregnation method. It was found that the catalyst supported on the CeO2 nanoparticles (5Ni/NPs) exhibited much higher catalytic activity and better stability than those of catalysts with other morphological CeO2 supports. Thus, the catalytic performance of Ni/CeO2 catalysts could be facilely tuned and optimized by precisely designing the morphology of the CeO2 support. The XPS, CO2-TPD, and H2-TPR characterizing techniques showed that Ni-based catalysts supported on nano-CeO2 with varied morphologies displayed different catalytic performances. It was supposed that the typical merits, such as the abundant oxygen vacancy, medium basic sites, moderate metal-support interaction, excellent reduction ability, etc., were considered as the main origins for the enhancement of the low-temperature catalytic activities. Furthermore, the kinetic study revealed that the Ni-based catalysts supported on the nano-CeO2 with varied morphologies performed the different apparent activation energies toward CO2 methanation. The specific reaction intermediates and possible reaction pathways were carefully investigated through the in-situ DRIFTS and online TPSR techniques. Overall, this work would provide new perspectives that the roles of the morphology effect of the support ought to be emphatically considered when designing new catalysts.

中文翻译：

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在具有不同形态的纳米 CeO2 负载的镍基催化剂上进行 CO2 甲烷化


通过控制水热法的参数，成功制备了一系列具有特殊形态的 CeO2 载体（纳米棒、纳米立方体、纳米八分子和纳米颗粒）。所得的纳米 CeO2 材料作为载体，采用初期浸渍法制备的镍基 CO2 甲烷化催化剂。研究发现，负载在 CeO2 纳米颗粒 （5Ni/NPs） 上的催化剂比具有其他形态 CeO2 载体的催化剂表现出更高的催化活性和更好的稳定性。因此，通过精确设计 CeO2 载体的形貌，可以很容易地调整和优化 Ni/CeO2 催化剂的催化性能。XPS、CO2-TPD 和 H2-TPR 表征技术表明，负载在纳米 CeO2 上具有不同形态的镍基催化剂表现出不同的催化性能。假设低温催化活性的主要来源是低温催化活性增强的主要来源，如丰富的氧空位、中等碱性位点、适度的金属-载体相互作用、优异的还原能力等。此外，动力学研究表明，负载在纳米 CeO2 上的具有不同形态的镍基催化剂对 CO2 甲烷化产生了不同的表观活化能。通过原位 DRIFTS 和在线 TPSR 技术仔细研究了特异性反应中间体和可能的反应途径。总的来说，这项工作将提供新的视角，即在设计新的催化剂时应重点考虑载体的形态效应的作用。