Preparation And Research Of Li-LSX Molecular Sieve

As the Pressure Swing Adsorption(PSA) technology is more widely applied to nitrogen and oxygen separation, the demand of fine molecular sieve adsorbent with high adsorption capacity for nitrogen and large nitrogen/oxygen separation coefficient increase day by day. At present, the Li-LSX prepared by Li+ exchange with the low Si-Al ratio zeolites is recognized the optimal PSA adsorbent, but because of the difficulty of Li+ exchange, severe loss of lithium, it is difficult to industrialization under low production costs. Currently, only a few manufacturers can achieve large-scale industrial production of Li-LSX. Therefore, we are struggling to develop low-cost process route of Li-LSX.Compared to other exchange methods, solution method is more suitable for industrialization because of its mild exchange conditions and simple operation. It is very important prerequisite for industrial production to optimize exchange conditions and obtain experimental data on preparation of Li-LSX.This paper researched the skeleton structure of Li-LSX and exchange liquor remains by X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FT-IR), Inductive coupled plasma emission spectrometer(ICP), and evaluated the nitrogen adsorption capacity of Li-LSX by static adsorption device. Besides, the influence on nitrogen adsorption capacity by solid-liquid ratio, middle roasting, time and the order of mixing Ca2+ exchange was emphatically studied in this paper. It was the same to influence of calcinations temperature on spherical Li-LSX. And the story was studied, that the third and fourth exchange liquior remains was recycled to the first and second exchange. It was the most favorable conditions to improve nitrogen adsorption capacity, which was set as the solid-liquid ratio 0.043, no middle roasting, exchange time:3h,2h, 1h, 1h, Ca2+ exchange after Li+ exchange; As the calcinations temperature increased, nitrogen adsorption capacity of spherical Li-LSX decreased. Most of all, the third and fourth exchange liquor remains, with Na+ concentration 800mg/L and 270mg/L, could be recycled to the first and second exchange, and made the exchange degree about 78.71-80.4% and 92.3-93.6% respectively.