导向剂室温老化合成低硅X型沸石

Synthesis of low-silica X-zeolite (LSX) via crystallization directing agent under aging at room temperature

  • 摘要: 利用导向剂室温(15~30℃)老化后高温晶化合成低硅X型沸石(LSX),用XRD测定样品晶型.对导向剂作用的研究表明,加入老化5h的导向剂17Na2O·6SiO2·Al2O3·250H2O可抑制LSX样品中的羟基方钠石(HS)杂晶,但没有加快LSX反应体系的晶化速度.对原料配比和反应条件的研究表明,产物对H2O/(Na2O+K2O)摩尔比和Na2O/(Na2O+K2O)摩尔比非常敏感,稍有变化就会引起杂晶的生成;随着室温老化和晶化温度的升高以及时间的延长,样品LSX结晶度增大.室温(25~30℃)老化12h、110℃晶化3h合成的LSX结晶度好、纯度高,Si/Al摩尔比为1.02±0.03.

     

    Abstract: Low-silica X zeolite (LSX) with the molar ratio 2.0 of SiO2 to Al2O3 was prepared by introducing the crystallization directing agent (CDA) under aging at room temperature(15-30℃)and crystallizing at 100-110℃. The crystal structure of LSX was characterized by XRD. The effect of CDA (17Na2O·6SiO2·Al2O3·250H2O) on the crystallization of LSX was studied. The results showed that the additive of CDA aged for 5 h could inhibit from impurity hydroxysodalite (HS) in LSX, but could not speed up the rate of crystallization. The study on the ratio of raw material showed that the purity of LSX was greatly influenced by the changes in molar ratio of H2O/(Na2O + K2O) and Na2O/(Na2O + K2O). The crystallinity of product LSX raised with increasing reaction temperature and aging time. The fine purity and crystallinity of the product could be obtained when aging for 12 h at room temperature (25-30℃) and crystallizing for 3 h at 110℃, and the molar ratio Si/Al of product LSX was 1.02±0.03.

     

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