Li-modified X molecular sieve and preparation method thereof

Abstract

The invention relates to a Li-modified X molecular sieve and a preparation method of the Li-modified X molecular sieve. The Li-modified X molecular sieve is characterized in that the host structure of the Li-modified X molecular sieve is X molecular sieve, and the Li-modified X molecular sieve consists of Li2O, Na2O, SiO2 and Al2O3 with the molar ratio of (0.9 to 1.0):(0 to 0.1):(2.0 to 3.0):1, wherein the exchange degree of Li<+> reaches up to 99% or higher. The preparation method of the Li-modified X molecular sieve comprises the following steps: exchanging X molecular sieve powder with ammonium salt; soaking the molecular sieve in a lithium salt solution; drying; and calcining to obtain the Li-modified X molecular sieve. The Li-modified X molecular sieve has the advantages that Li-modified X molecular sieve with high Li<+> exchange degree can be easily prepared by exchanging NH4<+> with Na<+>; and the lithium salt solution can be fully adsorbed by the molecular sieve by soaking, and the theoretical utilization rate can reach up to 100%, thereby lowering production cost of Li-modified X molecular sieve.

Description

technical field [0001] The invention relates to an X molecular sieve for air nitrogen and oxygen separation and a preparation method thereof, in particular to a lithium-containing modified X-type molecular sieve and a preparation method thereof, belonging to the field of nitrogen and oxygen separation adsorbents. Background technique [0002] Molecular sieves have pores of uniform size, which can adsorb material molecules of the same size as their pores. X molecular sieves, especially X molecular sieves that have been deeply exchanged by Li, have very good adsorption characteristics for nitrogen. Therefore, Li-modified X molecular sieves are used in industry to adsorb and separate nitrogen. Oxygen technology is widely used. [0003] Usually, the method for obtaining Li-modified X molecular sieves is to exchange synthetic or commercially available KNa-X molecular sieves with high-concentration soluble Li salt solutions several times, such as U.S. Patent Nos. 5,464,467, 5,932,...

AI Technical Summary

Problems solved by technology

[0005] Patent CN101125664A has announced the Li of a kind of sodium type low silicon X time-consuming molecular sieve + In the exchange method, Na-X molecular sieves are first roasted, then exchanged with Li+ aqueous solution, and finally LiNa-X molecular sieves with a certain degree of exchange are mixed with solid lithium salt powder for solid-phase exchange to obtain Li-modified materials with an exchange degree of more than 96%. X molecular sieve, but this method has problems such as uneven Li+ exchange and excessive Na ions

[0006] The method announced by the patent CN101766987A is to obtain the Li-LSX molecular sieve powder with a Li exchange degree greater than 95% after the commercially available low-silicon molecular sieve powder is modified by one-cross-one-baking, two-cross-two-baking and three-cross-Li; the method requires Roasting at 400~450 for 2 times, 2~3 hours each time, there is a problem that the X molecular sieve will reduce the crystallinity of the molecular sieve due to dealumination