Formation and Segregation of the Ru- and Rh-MgO Solid Solutions

IF 4.3 3区化学 Q2 CHEMISTRY, MULTIDISCIPLINARY

ACS Omega Pub Date : 2024-11-08 DOI:10.1021/acsomega.4c0647210.1021/acsomega.4c06472

Kazu Okumura*, Takumi Sasaki, Sou Sugihara, Kotaro Kawaguchi, Anas Abdullahi and Hikaru Iiyoshi,

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Abstract

Structural changes in Ru- and Rh-loaded magnesium oxide (MgO) subjected to thermal treatment were investigated by using X-ray absorption spectroscopy. The thermal treatment of the MgO-loaded Ru and Rh nanoparticles led to the formation of Ru-MgO and Rh-MgO solid solutions, respectively. The valences of Ru and Rh in the solutions were 4+ and 3+, respectively, as determined by the Ru and Rh K-edge X-ray absorption near-edge structure (XANES). The degree of solid solution formation was the highest at 873 and 1073 K in Ru-MgO and Rh-MgO, respectively, as observed in the extended X-ray absorption fine structure and XANES analyses. The nearest neighboring Ru–O and Rh–O bond distances were shorter than the Mg–O bond in MgO. The dispersion of Ru and Rh on the MgO surface, measured by CO adsorption, increased for samples thermally heated at 1273 K, suggesting that the segregation of Ru or Rh from the solid solutions occurred at this temperature. Consequently, a relatively high dispersion was realized in the sample thermally heated to 1273 K. A good correlation was found between the dispersion value of Ru in Ru/MgO and the NH₃ decomposition activity.

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Ru 和 Rh-MgO 固溶体的形成和分离

利用 X 射线吸收光谱法研究了热处理后负载 Ru 和 Rh 的氧化镁（MgO）的结构变化。热处理氧化镁负载的 Ru 和 Rh 纳米粒子后，分别形成了 Ru-MgO 和 Rh-MgO 固溶体。根据 Ru 和 Rh K 边 X 射线吸收近边结构（XANES）的测定，溶液中 Ru 和 Rh 的价数分别为 4+ 和 3+。根据扩展 X 射线吸收精细结构和 XANES 分析，在 873 和 1073 K 时，Ru-MgO 和 Rh-MgO 的固溶体形成程度最高。最近相邻的 Ru-O 和 Rh-O 键的距离比氧化镁中的 Mg-O 键短。通过 CO 吸附测量，在 1273 K 下热处理的样品中，Ru 和 Rh 在氧化镁表面的分散度增加，这表明在此温度下 Ru 或 Rh 从固溶体中发生了偏析。在 Ru/MgO 中 Ru 的分散值与 NH3 分解活性之间存在良好的相关性。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

ACS Omega Chemical Engineering-General Chemical Engineering

CiteScore

6.60

自引率

4.90%

发文量

3945

审稿时长

2.4 months

期刊介绍： ACS Omega is an open-access global publication for scientific articles that describe new findings in chemistry and interfacing areas of science, without any perceived evaluation of immediate impact.