Pore diameter effects on thermal stability of lanthanum-modified γ-Al2O3

IF 9.6 1区化学 Q1 CHEMISTRY, APPLIED

Journal of Rare Earths Pub Date : 2026-10-01 Epub Date: 2025-10-01 DOI:10.1016/j.jre.2025.09.041

Jie Dong, Meiqing Shen, Haoxuan Liu, Wei Li, Feng Gao

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引用次数: 0

Abstract

To investigate the impact of pore diameter on the thermal stability of La-doped transition aluminas, we examined three γ-Al₂O₃ materials with distinct pore diameters, both with and without La doping. Via material characterizations including N₂ adsorption–desorption, X-ray diffraction (XRD), thermogravimetric analysis, X-ray photoelectron spectroscopy (XPS), ²⁷Al and ¹H nuclear magnetic resonance (NMR), we discover that in the absence of La doping, the thermal stability of Al₂O₃ decreases significantly with decreasing pore diameter. For La-doped Al₂O₃, the influence of pore diameter on thermal stability is mitigated at 1100 °C but re-emerges at 1200 °C. We propose that the La species that provide structure protection are highly, or even atomically dispersed on the alumina surface. La₂O₃ or LaAlO₃ aggregates, if even present, are not the main La moieties that provide structure protection. The highly dispersed La species occupy defective sites on Al₂O₃, effectively slowing down phase transformation to α-Al₂O₃. At 1200 °C, La diffuses into the Al₂O₃ bulk and as such, loses its protective function.

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孔径对镧修饰γ-Al2O3热稳定性的影响

为了研究孔径对La掺杂过渡氧化铝热稳定性的影响，我们研究了三种不同孔径的γ-Al2O3材料，包括La掺杂和未掺杂。通过N2吸附-解吸、x射线衍射（XRD）、热重分析、x射线光电子能谱（XPS）、27Al和1H核磁共振（NMR）等材料表征发现，在没有La掺杂的情况下，Al2O3的热稳定性随着孔径的减小而显著降低。对于la掺杂的Al2O3，孔径对热稳定性的影响在1100℃时减弱，但在1200℃时再次出现。我们提出，提供结构保护的La物质高度分散，甚至原子分散在氧化铝表面。La2O3或LaAlO3聚集体即使存在，也不是提供结构保护的主要La基团。高度分散的La占据了Al2O3上的缺陷位点，有效减缓了α-Al2O3的相变。在1200℃时，La扩散到Al2O3体中，因此失去了保护功能。

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

Journal of Rare Earths 化学-应用化学

CiteScore

8.70

自引率

14.30%

发文量

374

审稿时长

1.7 months

期刊介绍： The Journal of Rare Earths reports studies on the 17 rare earth elements. It is a unique English-language learned journal that publishes works on various aspects of basic theory and applied science in the field of rare earths (RE). The journal accepts original high-quality original research papers and review articles with inventive content, and complete experimental data. It represents high academic standards and new progress in the RE field. Due to the advantage of abundant RE resources of China, the research on RE develops very actively, and papers on the latest progress in this field emerge every year. It is not only an important resource in which technicians publish and obtain their latest research results on RE, but also an important way of reflecting the updated progress in RE research field. The Journal of Rare Earths covers all research and application of RE rare earths including spectroscopy, luminescence and phosphors, rare earth catalysis, magnetism and magnetic materials, advanced rare earth materials, RE chemistry & hydrometallurgy, RE metallography & pyrometallurgy, RE new materials, RE solid state physics & solid state chemistry, rare earth applications, RE analysis & test, RE geology & ore dressing, etc.