Abstract

The powders of Rh and CeO₂ are synthesized by pulsed laser ablation in liquid. The Rh–CeO₂ model catalysts are prepared by the calcination of these powders in a wide temperature range from 450 °C to 1000 °C. The formation of individual and mixed (rhodium- and cerium-containing) phases with increasing temperature of catalyst calcination is studied by powder XRD and Raman spectroscopy. The redox properties of prepared catalysts are tested in a temperature-programmed reaction of CO reduction; their catalytic properties are studied on the example of CO oxidation. It is shown that the catalysts remain stable during catalytic tests due to the formation of a nano-heterophase system consisting of rhodium oxide (Rh₂O₃) and cerium oxide (CeO₂) nanoparticles. The discovered high stability is most likely explained by the formation of the Rh³⁺–CeO₂ species with the localization of Rh³⁺ ions in subsurface CeO₂ layers due to the contacts between rhodium oxide and cerium oxide nanoparticles. Introducing Rh³⁺ ions into Ce⁴⁺ positions of the CeO₂ lattice distorts the cerium oxide structure and leads to the formation of active oxygen species interacting with CO at low temperatures. The catalysts are shown to preserve high activity in the reaction of low-temperature CO oxidation even after the calcination at 1000 °C.

中文翻译：

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液体中脉冲激光烧蚀制备模型 Rh-CeO2 催化剂

摘要

在液体中通过脉冲激光烧蚀合成了Rh和CeO ₂粉末。Rh-CeO ₂模型催化剂是通过在450 °C 至1000 °C 的宽温度范围内煅烧这些粉末来制备的。通过粉末 XRD 和拉曼光谱研究了随着催化剂煅烧温度升高单独相和混合相（含铑和铈）的形成。在程序升温的CO还原反应中测试了所制备催化剂的氧化还原性能；以CO氧化为例研究了它们的催化性能。结果表明，由于形成了由氧化铑（Rh ₂ O ₃）和氧化铈（CeO ₂）纳米粒子组成的纳米多相体系，催化剂在催化测试过程中保持稳定。^{所发现的高稳定性很可能是由于Rh 3+} -CeO ₂物质的形成以及由于氧化铑和氧化铈纳米颗粒之间的接触而导致Rh ³⁺离子定位在次表面CeO _{2层中来解释的。}将Rh ³⁺离子引入CeO _2晶格的Ce ⁴⁺位置会扭曲氧化铈结构并导致在低温下与CO相互作用的活性氧物质的形成。即使在 1000 °C 下煅烧后，该催化剂仍能在低温 CO 氧化反应中保持高活性。