Development of Functional Adsorbent for Air Separation by Addition of Metal Cluster Ion into Zeolites

吸附法是制氧的有效空分工艺之一。近年来，为了降低成本和能源，对高性能的吸附剂提出了很高的要求。为了开发高性能的空分吸附剂，本研究在表面分析(光谱分析和热力学分析等)的基础上对沸石吸附剂进行了改性。1.利用金属离子团簇离子对沸石表面进行改性，制备了Li-CuLSX和Li-Ag-LSX，以提高分子筛对N_2的选择性吸附量。即在低硅沸石分子筛(LSX沸石)的方钠石笼和/或D6R中形成Ag和Cu2+离子簇，以物理方式封闭无效阳离子中心(Site-I)，并将Li+离子交换到簇离子还原生成的新的阳离子中心，制备出稳定的高比表面积吸附剂，优化了制备条件。2.对含LSX分子筛的金属离子簇进行了表面分析。为了分析Li-CuLSX和Li-Ag-LSX分子筛的表面性质，以CO和CH4为吸附探针分子，用红外光谱研究了它们的吸附中心特征。Li-CuLSX对CO的吸附量是Li-LSX的3倍左右。结果表明，采用团簇离子掺杂的方法，Li~(2+)离子选择性地交换到了Ⅲ位。甲烷吸附实验表明，III位的静电场比Li-LSX位的强。这一现象可能归因于D6R和/或方钠石笼中存在的铜团簇离子的影响。3.Li-CuLSX对氮气和氧气的吸附和空分特性。对不同吸附剂的气体吸附分离特性进行了定量分析。在211K时，Li-CuLSX的空气分离系数大于Li-LSX。

An adsorption method is one of the effective air separation processes to oxygen produce. Recently, the high-performance adsorbent is strongly required for cost and energy reduction. In this study, to develop a high performance adsorbent for air separation, zeolite adsorbents were modified based on the surface analyses (spectroscopy and thermodynamic analyses etc.). The result obtained in this work is summarized as follows.1.Modification of zeolite surface using metal ion cluster ions.To enhance the amount of N_2 selective adsorption site, Li-CuLSX and Li-Ag-LSX were prepared. Namely, Ag and Cu ion clusters were formed in sodalite cage and/or D6R of low silica X zeolite (LSX zeolite) in order to block ineffective cationic sites (site-I) physically, and Li^+ ions were exchanged into new cation sites created by reduction of the cluster ions, To prepare stable adsorbents with high surface area, the preparing condition were optimized.2.Surface analysis of metal ion cluster included LSX zeolites.In order to analyze surface properties of Li-CuLSX and Li-Ag-LSX, the characteristics of adsorption sites were studied by infrared spectroscopy using CO and CH_4 as adsorption probe molecules. Amount of CO adsorption on Li-CuLSX enhanced to about 3 times than that on Li-LSX. The result showed that Li^+ ions were selectively exchanged to site III using the cluster ion doping method. Furthermore, the methane adsorption showed that the electrostatic field of site III was stronger than that of Li-LSX. This phenomenon may be attributed to an effect of copper cluster ions existed in D6R and/or sodalite cage.3.N_2 and O_2 adsorption and air separation characters of Li-CuLSX.The quantitative analyses of gas absorption and separation characteristics for various adsorbents were carried out. At 211K, air separation factor of Li-CuLSX is larger than that of Li-LSX.