| Li-LSX has extensive application in gas separation, particularly, the process of Pressure Swing Adsorption (PSA) and Vacuum Swing Adsorption (VSA), due to its advantages of high nitrogen adsorption capacity, large nitrogen/oxygen separation faction and easy desorption. Water ion-exchange method with mild exchange condition and easy operation is widely used in industry. But it is difficult to reach high ion-exchange degree and it has a low utilization ratio of lithium and poor recovery of Li+.In this thesis, a new method combining the advantages of water ion-exchange technique and high-temperature solid state ion exchange route is established, by which, a high ion-exchange degree of Li-LSX is easily reached and the amount of Li salt is decreased. Effects of many parameters on the technological processing of new method above are discussed in detail, and the main results are shown below:1. The best ion-exchange conditions in water ion-exchange process are obtained: ion-exchange temperature: 90oC in aqueous, concentration of LiCl solution: 0.4mol/L, ion-exchange times: 4 and hours every time: 2. In these conditions, the ion-exchange degree of Li-LSX can be reached around 96%, which is satisfied for requirements of industrial use;2. When the ion-exchange degree reached 86.6% during two times of exchange process in aqueous at 90oC, the Li+ utilization ratio is below 10% by further exchange, such as in the third and even the fourth exchange process;3. On the basis of above ion exchange conditions in which (Li, Na)-LSX ion-exchange degree is around 86.6%, a high-temperature solid state ion exchange method is investigated and the best conditions are as following that: after mixed mechanically, (Li, Na)-LSX and LiCl powder with a molar ratio of residual Na+ of (Li, Na)-LSX and LiCl around 1:1.5, the mixture is heated, according to the following program: firstly, heating to 120oC at the rate of 1oC /min, and holding for 120min; secondly, heating to 200oC at the rate of 1.33oC /min and holding for 120min; thirdly, heating to 350oC at the rate of 2.5oC /min and holding for 180min; finally, natural cooling down.Meanwhile, the samples were characterized by means of FT-IR, TG-DTA, XRD and SEM. The conclusions are summarized follows:1. According to the FT-IR spectra, it is shown that the characteristic peaks of the framework are not changed with comparison of the samples before and after ion exchange process especially vibration peak of the Si-O-Al. However, because the radius of Li+ is smaller than that of Na+, it has the smaller influence on the framework vibration. For example, the peaks location of tetrahedron internal expansion vibration is moved from 664.75cm-1 and 696.37cm-1 to 668.70cm-1, and a small shift peak at near 696cm-1 is shown; Meanwhile, the peaks location of tetrahedron external expansion vibration is moved from 742.42cm-1 to 746.53cm-1; the peaks location of double-ring vibration turn from 557.48cm-1 to 584.95cm-1;2. The TG-DTA curves displays that the peak of losing water is moved to high temperature compared with other literature reported, suggesting that the adsorption capacity for H2O is increased; Meanwhile, the collapse temperature of the framework is increased from less than 600 oC to 700 oC, meaning that the thermal stability is also increased;3. In the XRD patterns, almost all characteristic peaks of Li-LSX move to large angle, indicating that the crystal unit cell is decreased. The main reason is that the smaller ion of Li+ is displaced for Na+ and therefore the framework is shrunk;4. SEM images show that the particle size of Li-LSX is around 5μm with narrow distribution;5. With comparison of the Li-LSX samples prepared by water ion-exchange technique and high-temperature solid state ion exchange route, the structure properties of the both are silimar with the help of FT-IR,TG-DTA,XRD,SEM analysis results.
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