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  • 快速溶膠凝膠法制備鉀霞石及其反應機理

    Synthesis and characterization of kalsilite powder using a fast sol-gel method

    • 摘要: 在不使用任何有機溶劑的條件下,使用氨水調節pH值,正硅酸乙酯-硝酸鉀-硝酸鋁-水體系在5~12min內即迅速膠凝.干凝膠在862℃下熱處理生成的鉀霞石物相單一、顆粒大小均勻、平均粒徑為8μm.硝酸鹽水解產生的氫離子以及隨后加入的氨水相當于進行了先酸后堿的催化,促使正硅酸乙酯(以TEOS表示)迅速水解、聚合.27Al NMR分析證實鋁硅酸鹽溶膠聚合按照五配位鋁中間體機理進行.

       

      Abstract: Nitrate replaced alkoxide and alcohol solvent omitted, a TEOS-KNO3-Al(NO3)3-H2O system turned into gel in 5~12 min with pH adjusted by aqua ammonia. Dried gel treated at 862℃, pure and homogeneous kalsilite powder was prepared with an average particle size of 8μm. The TEOS hydrolysis reaction was catalyzed by H+ released from aluminum nitrate hydrolysis firstly, and then promoted again by OH- with the addition of aqua ammonia. The gelation time was shortened greatly owing to the catalysis mode of acid first and alkali second. A penta-coordination Al was detected by 27Al NMR analyzing the dried aluminosilicate gel.

       

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