Method for preparing LiLSX molecular screen

Abstract

The invention relates to a preparation method for a LiLSX molecular sieve, which comprises the steps that LSX zeolite is prepared, LSX is exchanged into KLSX, K2SO3 solution is adopted and KOH solution is used for regulating the PH value to 8.5, a method of displacing for a plurality of times is used with 2 minutes of replacing time for each replacement and the temperature of the solution is about 80 DEG C, exchange liquid after being exchanged a plurality times is used in the next group of the exchange process of K<+>; then a method that is similar to the replacement of K<+> solution is adopted to exchange into NH4LSX, the PH value of the solution is 8.5; then LiOH solution is used for exchanging Li<+> into LiLSX at the temperature of 50 DEG C and air is added to discharging NH3 at the same time; finally, washing, drying, etc. are carried out and finished products are obtained. The method is characterized by adopting ion exchange in a short time, using substances exchanged circularly and having suitable temperature and PH values of exchange solutions and high utilization ratio of Li, and finally the LiLSX molecular sieve with high degree of crystallinity is obtained.

Description

technical field [0001] The invention relates to a preparation method of a molecular sieve, in particular to a preparation method of a LiLSX molecular sieve. Background technique [0002] LiLSX molecular sieve is used as an adsorbent for pressure swing adsorption air separation and oxygen production. The oxygen and nitrogen separation coefficient is 2-3 times that of traditional 5A and 13X. The large-scale pressure swing adsorption air separation oxygen production device manufactured with this adsorbent is only 5A molecular sieve. 1 / 5 of that, and the power consumption of oxygen production is also more than 20% lower. The key technology for preparing LiLSX molecular sieve adsorbent is Li + exchange technology. Because the synthesized LSX molecular sieve contains Na + and K + , after Li + The exchange transforms into LiLSX molecular sieves, and Li + The degree of exchange is generally required to be above 88%. + The higher the degree of exchange, the better the performa...

AI Technical Summary

Problems solved by technology

Thanks to Li + The radius is small, and the hydration ability is extremely strong. Using the existing technology, it is quite difficult to carry out ion exchange in aqueous solution. After 5 ion exchanges, each exchange, Li + It takes more than 6 times the amount of excess, and the exchange time is quite long, several hours or even dozens of hours each time, resulting in extremely low utilization rate of Li and long production cycle. Due to the high price of Li, the cost of LiLSX molecular sieve is quite high.

[0003] In US Pat. No. 5,916,836 (1999), Toufar et al. announced the new Li + Exchange method, first pass LSX through K + Exchange to KLSX, then via NH 4 + Exchange to NH 4 LSX, and finally NH 4 LSX for Li + Exchanged into LiLSX, the utilization rate of Li is greater than 90%, in this preparation method, with K 2 SO 4 Carry out K + Exchange, temperature 80°C, 1 hour each time, repeat 3 times, use (NH 4 ) 2 SO 4 carry out NH 4 + Exchange, temperature 80 ℃, 2 hours each time, repeat 4 times, the cycle of preparing LiLSX molecular sieve is quite long, it is difficult to industrialized production, and, K 2 SO 4 The pH of the solution is 3-4, soaked for a long time at 80°C, the LSX molecular sieve framework is damaged to a certain extent, and KLSX is exchanged into NH 4 LSX will also be destroyed to a certain extent at 80°C, and finally exchanged into LiLSX, and its crystallinity will decrease significantly, which will affect the adsorption performance and life of LiLSX.