Rare earth-containing Li-LSX zeolite as well as preparation method and application thereof

Abstract

The invention relates to rare earth-containing Li-LSX zeolite and a preparation method thereof, and belongs to the technical field of chemical engineering. The preparation method comprises the following steps: (1) adding a silicon source, an aluminum source and caustic alkali according to the molar ratio of M2O / SiO2 = 1-1.5, the molar ratio of SiO2 / Al2O3 = 2.5-5 and the molar ratio of H2O / SiO2 = 45-50, mixing and stirring, and crystallizing at 80-100 DEG C for 5-10 hours; (2) after filtering, exchanging a product with a rare earth salt solution for 1-2 times, and roasting at 350-550 DEG C for 0.5-3 hours after primary exchange; (3) after grinding, supplementing and adding a silicon source, an aluminum source and caustic alkali according to the proportion of 40%-95% of the total mass of a dry basis, enabling the total molar ratio of materials to be M2O / SiO2 = 3.5-4 (the molar ratio of Na / K of alkali metal M is 2.5-3.5), SiO2 / Al2O3 = 1.5-2 and H2O / SiO2 = 70-75, stirring, aging for 1-3 days, and crystallizing again at 60-80 DEG C for 10-25 hours; and (4) after filtration and ammonium salt exchange, carrying out ion exchange for 2-5 times by using a lithium compound solution, and roasting for 1-2 times at intervals at 300-430 DEG C / 0.5-3 hours. The lithium salt utilization rate is high in preparation, the product composition and performance are easy to adjust, and the product has better adsorption separation performance when being used as an oxygen production adsorbent.

Description

technical field [0001] The invention relates to a rare earth-containing Li-LSX zeolite and its preparation method and application, in particular to a low-silicon-aluminum-ratio X-type zeolite containing cerium and lithium, its preparation method and the process of oxygen separation and purification The application belongs to the field of chemical technology. Background technique [0002] The fields of application of oxygen and nitrogen are becoming more and more extensive, and the demand is also increasing. Among them, oxygen is the basis for human survival, and because of its strong oxidizing properties and life-sustaining properties, as an important chemical raw material, it is widely used in petrochemical, chemical synthesis, iron and steel smelting, nonferrous metallurgy, metal cutting and welding , paper industry, fish farming, plateau operations, tunnel construction, wastewater treatment and environmental protection and other aspects. With the continuous improvement ...

AI Technical Summary

Problems solved by technology

This type of prior art mainly uses kaolin as a binder. After high-temperature roasting, a mixed solution of sodium hydroxide or sodium silicate is used for aging crystallization. The kaolin product is mainly converted into A-type zeolite or X-type zeolite, but its Smaller adsorption capacity than LSX zeolite

[0012] Chinese patent CN101524637A also discloses a preparation method of a binder-free adsorbent rich in LSX zeolite. This patent uses NaLSX as an active component and kaolin as a binder, by adding an alkali source and a silicon source (which can be (without adding) for molding and roasting, and crystallization by adding sodium hydroxide lye to convert the kaolin binder into X-type zeolite, but the product has a relatively high silicon-alumina ratio, which affects the adsorption capacity

In a Li-modified X molecular sieve disclosed in Chinese patent ZL201110305323.8 and its preparation method, the original X zeolite powder is first exchanged with ammonium salt, and then the lithium salt solution is impregnated on the zeolite by an impregnation method, and then dried and roasted to obtain LiX, but it is still an X-type zeolite, and its adsorption performance is still poor

[0034] Chinese patents CN101125664A, CN100556808C, and ZL200710121786.2 all disclose an ion exchange method for preparing lithium-type low-silicon-aluminum X-type zeolite. First, the sodium-type low-silicon-alumina X-type zeolite has a certain lithium ion exchange degree, and then use the solid phase exchange method to obtain lithium-type low-silicon-alumina X-type zeolite, so that the final lithium ion exchange degree is greater than 96%, but its oxygen adsorption performance is poor

[0044] Chinese patent CN1071592C has reported an oxygen selective adsorbent capable of separating oxygen from a gas mixture, which loads a transition element complex evenly spaced from each other on a substrate with a high surface area, and has an oxygen adsorption capacity greater than 0.3 mmol / g, the oxygen absorption rate is greater than 0.3 mmol / g per minute, and can be used in pressure swing adsorption process to prepare oxygen with a purity greater than 99%; however, this type of transition element absorbent is difficult to manufacture, and the cost is high Trace impurities are sensitive and difficult to apply in practice

The exchange degree of lithium is not high, because there is an ion competition adsorption process in the water heat exchange process of different ions, it is not easy to adjust the composition and stable control; moreover, repeated acid exchange and roasting processes will cause damage to the structure of zeolite and The ratio of silicon to aluminum increases, and the utilization rate of lithium ions is also low

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