Ammonium Ion Exchange of Synthetic Zeolites: The Effect of Their Open‐Window Sizes, Pore Structures, and Cation Exchange Capacities
Ammonium Ion Exchange of Synthetic Zeolites: The Effect of Their Open‐Window Sizes, Pore Structures, and Cation Exchange Capacities
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合成沸石的铵离子交换：开窗尺寸、孔结构和阳离子交换容量的影响
DOI：
10.1081/ss-120039306
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Y. Moriyoshi
中科院分区：
文献类型：
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作者：
Yujiro Watanabe;H. Yamada;J. Tanaka;Y. Komatsu;Y. Moriyoshi
合成沸石的铵离子交换行为，通过改变铵离子的初始浓度和反应时间，研究了方钠石（SOD）、rho沸石（RHO）、林德A型沸石（LTA）和八面沸石（FAU）的反应。铵离子交换行为取决于这些沸石的开窗尺寸、孔结构和阳离子交换容量。关于具有Na+离子的方钠石（Na-SOD），铵离子交换在平衡状态下不完全发生，因为开窗口尺寸小于铵离子的直径。对于具有Na+和Cs+离子的RHO（NaCs-RHO），笼中的较大阳离子Cs+离子在初始阶段阻碍离子交换。随着反应时间的延长，铵离子交换量逐渐增加，最终达到平衡。关于具有Na+离子的LTA（Na-LTA），交换的铵离子的量随着反应时间的增加而减少，然后达到平台。结果表明，在初始阶段，α-笼上的离子交换和β-笼上的物理吸附同时发生，随后是α-笼上的离子交换平衡状态。关于具有Na+离子的FAU（Na-FAU），没有观察到对反应时间的依赖性，因为开放窗口的尺寸对于铵离子的离子交换足够大。在这些沸石中具有最大开放窗口的Na-FAU显示出最高的铵离子交换容量，为3.20 mmol/g。
Abstract Ammonium ion exchange behavior of synthetic zeolites, i.e., sodalite (SOD), rho zeolite (RHO), Linde type A zeolite (LTA), and faujasite zeolite (FAU), was investigated by changing the initial concentration of ammonium ions and reaction time. Ammonium ion exchange behavior was dependent on the open‐window sizes, the pore structures, and the cation exchange capacities of these zeolites. Regarding sodalite with Na+ ions (Na‐SOD), ammonium ion exchange did not completely occur at the equilibrium state because the open‐window size is smaller than the diameter of ammonium ions. Regarding RHO with Na+ and Cs+ ions (NaCs‐RHO), the larger cations, Cs+ ion, in the cages obstructed the ion exchange at the initial stage. However, the amount of exchanged ammonium ions gradually increased with increasing reaction time, finally achieving equilibrium. Regarding LTA with Na+ ions (Na‐LTA), the amount of exchanged ammonium ions decreased with increasing reaction time, and then reached plateau. It indicated that both the ion exchange on the α‐cages and physical adsorption on the β‐cages occurred at the initial stage, which was followed by the equilibrium state of ion exchange on the α‐cages. Regarding FAU with Na+ ions (Na‐FAU), no dependence on reaction time was observed, because the size of the open‐windows is large enough for ion exchange of ammonium ions. The Na‐FAU, which has the biggest open‐windows among these zeolites, showed the highest exchange capacity for ammonium ions, 3.20 mmol/g.