Abstract The aim of this work was to derive γ-alumina from gels prepared by hydrolysis of aluminum (Al) sec-butoxide (Asb) chelated with ethyl acetoacetate (Eaa) in various ratios and to determine the effect of Eaa on the properties of obtained alumina. Gels and γ-alumina were investigated by nuclear magnetic resonance, X-ray diffraction, scanning electron microscopy and N2 adsorption–desorption isotherms. The results show that the Eaa/Asb ratio greatly affects the gelation process. At higher Eaa/Asb ratios, hydrolysis resistant tris(ethyl acetoacetate)aluminum (III) is formed, causing a less complete gelation process. Aluminum coordination in samples varies from six-fold coordination in tris(ethyl acetoacetate)aluminum (III) to less defined five-fold coordinated sites of Al in the gel. Thermal treatment at 800 °C for 2 h induces γ-Al2O3 crystallization. A partial transformation to α-Al2O3 is observed after thermal treatment at 900 °C for 2 h for some samples. Transformation to α-Al2O3 after thermal treatment at 1000 °C for 2 h is complete for all samples. In addition to thermal stability of samples, the Eaa/Asb ratio also influences morphology of γ-Al2O3 crystallized at 800 °C. In samples with lower Eaa/Asb ratio, particles appear compact, but are cavernous for samples with higher Eaa/Asb ratios.

中文翻译：

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通过在溶胶-凝胶合成中用乙酰乙酸乙酯改性仲丁醇铝来调整 γ-氧化铝的微观结构、结构和热性能

摘要 本工作的目的是从以不同比例与乙酰乙酸乙酯 (Eaa) 螯合的仲丁醇铝 (Asb) 水解制备的凝胶中提取 γ-氧化铝，并确定 Eaa 对所得凝胶性质的影响。氧化铝。通过核磁共振、X 射线衍射、扫描电子显微镜和 N2 吸附-解吸等温线研究了凝胶和 γ-氧化铝。结果表明，Eaa/Asb 比极大地影响凝胶化过程。在较高的 Eaa/Asb 比率下，会形成耐水解的三（乙酰乙酸乙酯）铝 (III)，导致胶凝过程不完全。样品中的铝配位从三（乙酰乙酸乙酯）铝 (III) 中的六倍配位到凝胶中铝的不太明确的五倍配位。在 800°C 下热处理 2 小时会诱导 γ-Al2O3 结晶。对于某些样品，在 900 °C 下热处理 2 小时后观察到部分转变为 α-Al2O3。所有样品在 1000°C 热处理 2 小时后完全转化为 α-Al2O3。除了样品的热稳定性外，Eaa/Asb 比也会影响 800 °C 结晶的 γ-Al2O3 的形貌。在 Eaa/Asb 比率较低的样品中，颗粒看起来很紧凑，但对于 Eaa/Asb 比率较高的样品，颗粒呈海绵状。