In the present study, the pore space of a mesoporous cerium oxide material is investigated, which forms by the self-assembly of primary particles into a spherical secondary structure possessing a disordered mesopore space. The material under study exhibits quite stable mesoporosity upon aging at high temperatures (800 °C) and is, thus, of potential interest in high-temperature catalysis. Here, different characterization techniques were applied to elucidate the structural evolution taking place between heat treatment at 400 °C and aging at 800 °C, i.e., in a water-containing atmosphere, which is usually detrimental to nanoscaled porosity. The changes in the mesoporosity were monitored by advanced physisorption experiments, including hysteresis scanning, and electron tomography analysis coupled with a 3D reconstruction of the mesopore space. These methods indicate that the 3D spatial arrangement of the primary particles during the synthesis under hydrothermal conditions via thermal hydrolysis is related to the thermal stability of the hierarchical mesopore structure. The assembly of the primary CeO₂ particles (∼4 nm in size) results in an interparticulate space constituting an open 3D mesopore network, as revealed by skeleton analysis of tomography data, being in conformity with hysteresis scanning. At elevated temperatures (800 °C), sinter processes occur resulting in the growth of the primary particles, but the 3D mesopore network and the spherical secondary structure are preserved.

中文翻译：

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具有高表面积和高热稳定性的介孔氧化铈纳米材料的综合表征

在本研究中，研究了介孔氧化铈材料的孔空间，该孔空间是通过将初级粒子自组装成具有无序中孔空间的球形二级结构而形成的。所研究的材料在高温（800°C）下老化时表现出相当稳定的介孔性，因此在高温催化中具有潜在的意义。在这里，应用了不同的表征技术来阐明在400°C的热处理和800°C的老化之间（即在通常不利于纳米级孔隙率的含水气氛中）发生的结构演变。通过先进的物理吸附实验（包括磁滞扫描，电子断层扫描分析以及介孔空间的3D重建）来监测介孔的变化。这些方法表明在通过热水解的水热条件下合成期间，初级粒子的3D空间排列与分级中孔结构的热稳定性有关。主要CeO的组装如层析数据的骨架分析所揭示的那样，_2个粒子（大小约为4 nm）形成了构成开放3D中孔网络的微粒间空间，这与磁滞扫描一致。在高温（800°C）下，会发生烧结过程，从而导致一次颗粒的生长，但保留了3D中孔网络和球形二次结构。