In thid study, Ni/CeO₂ catalysts were prepared by a one-step co-precipitation of nickel and cerium salts in a NaOH solution treated by different heating methods including microwave (MW), hydrothermal (HM) and evaporation (EP). With TEM observation, the co-precipitation provided the catalysts containing a highly crystalline CeO₂ of a (111) plane structure with d-spacing of 3.15–3.24 Å. The obtained CeO₂ nanoparticles exhibited a pseudo-spherical shape with a size range of 10.8–12.1 nm. Based on HR-TEM analyses, NiO nanoparticles with a large size range of 48.8–51.2 nm were found to be incorporated within the CeO₂ nanostructure. By N₂ sorption measurement, all Ni/CeO₂ catalysts possessed a mesoporous characteristic with a specific surface area range of 70.5–75.7 m²/g and an average pore diameter of 30 nm. XRD results revealed that NiO species could be completely transformed into Ni⁰ species by the H₂ reduction process. XPS analyses further confirmed the presence of Ni⁰ species with a prominent peak at an energy bandgap of 852.6 eV. Hydrogen temperature-programmed reduction (H₂-TPR) confirmed that α and β peaks of NiO species were completely reduced at a temperature lower than 500 °C. The Ni/CeO₂ catalyst prepared by MW method exhibited a higher strong metal-support interaction (SMSI) between Ni and CeO₂ revealed by H₂ consumption results. The Ni/CeO₂ catalysts prepared by MW, HM, EP methods exhibited the CO₂ methanation activity with TOF of 13.6, 10.8 and 5.8 s⁻¹, which could be correlated with the Ni crystallite sizes of 42.2, 50.5 and 52.8 nm, respectively. All prepared Ni/CeO₂ catalysts exhibited the stable catalytic performances with a negligible drop in CO₂ conversion and CH₄ selectivity over 72 h-time-on-stream test. In comparison, the MW method with a rapid and uniform heating under autogenous pressure could result in the Ni/CeO₂ catalyst with the superior catalytic activities due to the higher dispersion of Ni.

在这项研究中，通过在不同加热方法（包括微波（MW），水热（HM）和蒸发（EP））处理的NaOH溶液中，将镍和铈盐在镍溶液中进行一步共沉淀来制备Ni / CeO ₂催化剂。通过TEM观察，共沉淀提供了具有（111）平面结构且d-间距为3.15–3.24Å的高度结晶CeO ₂的催化剂。获得的CeO ₂纳米颗粒呈现出伪球形，尺寸范围为10.8-12.1 nm。根据HR-TEM分析，发现CeO ₂纳米结构中掺入了大小范围为48.8-51.2 nm的NiO纳米颗粒。通过N ₂吸附测量，所有Ni / CeO ₂催化剂具有介孔特性，比表面积范围为70.5-75.7 m ² / g，平均孔径为30 nm。XRD结果表明，通过H ₂还原过程，NiO物种可以完全转化为Ni ⁰物种。XPS分析进一步证实了Ni ⁰物种的存在，其能带隙为852.6 eV，具有突出的峰。氢程序升温还原（H ₂ -TPR）证实，在低于500°C的温度下，NiO物种的α和β峰被完全还原。在Ni /的CeO ₂由MW方法制备催化剂具有Ni和铈之间的较高强的金属-载体相互作用（SMSI）₂由H揭示₂消费结果。MW，HM，EP方法制备的Ni / CeO ₂催化剂表现出CO ₂甲烷化活性，TOF为13.6、10.8和5.8 s ^-1，这分别与42.2、50.5和52.8 nm的Ni微晶尺寸有关。 。所有制备的Ni / CeO ₂催化剂均显示出稳定的催化性能，在72小时的运行时间测试中，CO ₂转化率和CH ₄选择性的下降可忽略不计。相比之下，在自生压力下快速均匀加热的MW方法可能会导致Ni / CeO ₂催化剂具有较高的催化活性，这是因为Ni的分散性更高。