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本文考察了采用硅藻土为硅源的L型分子筛的合成中,硅藻土经水洗、碱溶等预处理和添加晶化导向剂的效应,以及用硅凝胶为硅源合成时,几种钾盐的阴离子基团对合成的影响。实验结果表明,经碱溶预处理后,硅藻土中的无定形硅石的胶溶作用是提高合成产物中L型分子筛含量的关键步骤,使结晶度由碱溶处理前的63.1%上升为84.9%。在用硅藻土为硅源的合成中,添加用硅凝胶作硅源制成的晶化导向剂,初步结果表明产物的结晶度降低对合成不利。实验也表明,在用硅凝胶为硅源的合成中,添加了不同量的KF、KCl、KBr、KI、KNO_3、KMnO_4、K_2SO_4及K_3PO_4等钾盐后,产物的结晶度都有所降低,对卤化物系列其添加量为0.02mol/L时进行比较,降低的顺序为:F~->CI~->Br~->I~-,而对于负电荷含量不同的阴离子基团,降低的顺序为:PO_4~(3-)>SO_4~(2-)>MnO_4~->NO_3~-.
This article examines the use of diatomite as the silicon source L-type molecular sieve synthesis, diatomite by washing, alkali and other pretreatment and the effect of adding crystallization guide agent, and the use of silica gel as a silicon source synthesis, the few Effect of Kinds of Anion Groups of Potassium Salt on the Synthesis. The experimental results show that the peptization of amorphous silica in diatomite after alkali pretreatment is the key step to increase the content of L-type zeolite in the synthesized product, and the crystallinity increases from 63.1% before alkali-soluble treatment to 84.9 %. In the synthesis of diatomite as a silicon source, the addition of a silica gel as a silicon source for the crystallization of the directing agent, the preliminary results show that the reduction of the product crystallinity disadvantageous to the synthesis. Experiments also show that the addition of different amounts of potassium salts such as KF, KCl, KBr, KI, KNO 3, KMnO 4, K 2 SO 4 and K 3 PO 4 in the synthesis of silica gel with silica gel reduced the crystallinity of the product, When the addition amount of halide series was 0.02mol / L, the order of decreasing was F ~ -> CI ~ -> Br ~ -> I ~, while for the anionic groups with different negative charge content, The order is: PO_4 ~ (3 -)> SO_4 ~ (2 -)> MnO_4 ~ -> NO_3 ~ -.