Si-modified mesoporous alumina with high thermal stability was synthesized from coal fly ash through a facile coprecipitation method using NH₄HCO₃ and NH₄Al(SO₄)₂. The effects of Si dopant contents on the characterization of alumina were investigated using X-ray diffraction, Fourier transform infrared spectroscopy, N₂ adsorption–desorption method and transmission electron microscopy. The results show that the introduction of Si effectively inhibits the phase transformation of mesoporous alumina from γ-Al₂O₃ to α-Al₂O₃. Compared with alumina obtained without Si dopant, the specific surface area of mesoporous alumina with adding 12 wt% Si improved from 5.2 to 227.5% by increasing the calcination temperature from 500 to 1200 °C, respectively. The specific surface area, pore volume and pore size of mesoporous alumina with 12 wt% Si calcined at 1100 °C are 149 m²/g, 0.52 cm³/g and 8.9 nm, respectively.

中文翻译：

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用粉煤灰共沉淀合成具有高热稳定性的硅改性介孔氧化铝

采用NH ₄ HCO ₃和NH ₄ Al（SO ₄）₂共混沉淀法，由粉煤灰合成了具有高热稳定性的硅改性介孔氧化铝。利用X射线衍射，傅里叶变换红外光谱，N ₂吸附-解吸方法和透射电子显微镜研究了硅掺杂剂含量对氧化铝表征的影响。结果表明，引入的Si有效地抑制从孔氧化铝的相变的γ-Al ₂ ö ₃到的α-Al ₂ ö ₃。与不添加Si掺杂剂得到的氧化铝相比，通过将煅烧温度从500℃提高到1200℃，添加了12wt％Si的中孔氧化铝的比表面积从5.2％提高到227.5％。在1100℃下煅烧的具有12wt％Si的中孔氧化铝的比表面积，孔体积和孔径分别为149m ² /g、0.52cm ³ / g和8.9nm。