沸石






兩種不同的天然沸石





活性氧化鋁有時也被用作沸石使用




4А 分子篩(人造分子篩)


沸石是一种含有水架状结构的铝硅酸盐矿物，最早发现于1756年。瑞典的矿物学家克朗斯提（Cronstedt）发现有一类天然铝硅酸盐矿石在灼烧时会产生沸腾现象，因此命名为沸石（瑞典文：zeolit）。在希腊文中意为“沸腾的石头”。此后人们对沸石的研究不断深入。


沸石因成分不同分为方沸石（Na[AlSi2O6]·H2O）和钙沸石（Ca[Al2Si3O10]·3H2O）。其含水量与外界温度及水蒸气的压力有关，加热时水分可慢慢逸出，但并不破坏其结晶构造。


晶体结构中有许多空腔（笼）和连接空腔的通道，水分子位于其中，可由通道运输。晶体和集合体形态及解理随着晶体结构的不同而异，一般呈浅色，玻璃光泽，硬度3－3.5，比重2.0－2.4。


沸石族矿物由低温热液作用形成，见于喷出岩，特别是玄武岩的孔隙中，也见于沉积岩、变质岩及热液矿床和某些近代温泉沉积中。


1932年，McBain提出了“分子筛”（Molecular sieve）的概念。表示可以在分子水平上筛分物质的多孔材料。沸石用作分子筛，可以吸取或过滤其他物质的分子。虽然沸石只是分子筛的一种，但是沸石在其中最具代表性，因此“沸石”和“分子筛”这两个词经常被混用。


除了天然产品外，也可由人工合成，人造沸石是：磺酸化聚苯乙烯，天然沸石：铝硅酸钠。




目录






  • 1 用途


  • 2 A型沸石


  • 3 磷酸铝沸石


  • 4 参見


  • 5 参考文献


  • 6 外部連結





用途




  • 吸附剂和干燥剂


  • 催化剂或助催化剂

  • 洗涤剂

  • 建筑材料

  • 其他用途（污水处理、土壤改良剂、肥料添加剂、药物载体、饲料添加剂、防止蒸餾過程中出現暴沸等）



A型沸石


A型沸石，代号LTA，是应用最广的人造硅酸盐沸石。典型品种组成为|Na12(H2O)27/8|[Al12Si12O48]，|Na64(H2O)326.71|[Si96Al96O384]或|Na91.7|[Si96Al96O384]。孔穴十分巨大。该型始于立方晶系，具立方面心晶胞，晶胞参数a{displaystyle a}a = 24.6Å左右。A型沸石具有吸附水分子的良好性能，干燥性能很高，易再生，可反复使用。5A型可以高效分立正丁烷和异丁烷，3A型可干燥乙烯、丙烯等气体。[1]



磷酸铝沸石


磷酸铝沸石，代号AFI，又称介孔磷酸铝(meso-porous aluminum phosphates)。典型组成是AlPO4。属于六方晶系，a{displaystyle a}a = 13.827Å，c{displaystyle c}c = 8.580Å。磷酸铝沸石具有优良的反应活性，可以制备单层碳纳米管；亦可用作催化剂，将乙烷氧化为乙二酸。[2]



参見


  • 矿物列表


参考文献




  1. ^ 无机化学. 高等教育出版社. 2002年第二版: 938页. ISBN 978-7-04-011583-3.  请检查|date=中的日期值 (帮助)


  2. ^ 无机化学. 高等教育出版社. 2002年第二版: 939页. ISBN 978-7-04-011583-3.  请检查|date=中的日期值 (帮助)



外部連結





规范控制


  • AAT: 300379647

  • GND: 4067660-2

  • NDL: 00563784



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