CaLi-LSX分子筛的制备及其母液循环利用

Preparation of CaLi-LSX zeolites and reuse of mother liquor

通过对Ca-LSX分子筛进行Li^(+)交换制备了不同锂交换度的CaLi-LSX分子筛,对分子筛的离子交换工艺进行了改进,通过母液回用法降低了离子交换过程中的锂盐用量,并采用XRD,ICP,FTIR等表征手段及吸附热、静态竞争吸附、Rietveld精修等模拟计算对分子筛进行分析。实验结果表明,随锂交换度的提高,CaLi-LSX分子筛的吸附容量整体呈下降趋势,氮氧分离系数先升高后降低,在锂交换度43.7%时达到最高值5.23,此时氮气吸附容量为28.94 cm^(3)/g;Rietveld精修结果显示,单个晶胞中有10.357个Li^(+)位于SⅢ位点;母液回用法制备的分子筛吸附性能无显著下降,重复性好,产品锂交换度和常温氮氧吸附容量均相差较小,可使锂盐用量降低约90.6%。

CaLi-LSX zeolites with different lithium exchange degrees were prepared by Li^(+)exchange on Ca-LSX zeolites.The ion exchange technology of the zeolite was improved,and the amount of lithium salt in the ion exchange process was reduced by reusing mother liquor.The zeolites were disclosed by XRD,ICP,and FTIR,and they were analyzed by simulation calculations of adsorption heat,static competitive adsorption,and Rietveld refinement.The experimental results show that with the rise of the lithium exchange degree,the adsorption capacity of the CaLi-LSX zeolite decreases,and the separation coefficient between nitrogen and oxygen increases first,followed by a decline.The highest separation coefficient of 5.23 is achieved at a lithium exchange degree of 43.7%,accompanied by the nitrogen adsorption capacity of 28.94 cm^(3)/g.The results of Rietveld refinement show that 10.357 Li^(+)are located at the S Ⅲ locate in a unit cell.The adsorption performance of zeolites prepared by reusing mother liquor does not decrease significantly and demonstrates good repeatability.In addition,there is almost no difference in the lithium exchange degree and the adsorption capacity of nitrogen and oxygen at room temperatures,and the lithium salt consumption is reduced by about 90.6%.