CN-117065718-B - Composite Li-Ca-Ce-LSX hydrophobic molecular sieve, preparation method and application thereof

Abstract

The invention discloses a composite Li-Ca-Ce-LSX hydrophobic molecular sieve, a preparation method and application thereof. The method is characterized in that Ca and Ce are further modified on the basis of the Li-LSX molecular sieve, and the composite Li-Ca-Ce-LSX hydrophobic molecular sieve is synthesized by an aqueous solution exchange method. The preparation method is simple, the granularity of the prepared composite Li-Ca-Ce-LSX hydrophobic molecular sieve is 0.2-0.4 mm, the composite Li-Ca-Ce-LSX hydrophobic molecular sieve has good crystallinity and adsorption performance, high polarizability, high adsorption capacity and nitrogen-oxygen separation coefficient for nitrogen, certain hydrophobicity, obvious improvement of the sensitivity of the molecular sieve to the environment, prolonged service life, and wide application fields, and can be used as a high-efficiency catalyst, a heavy metal ion adsorbent and a concrete additive.

Inventors

• LOU YUE
• SHI YIFAN
• TIAN LIANG

Assignees

• 南京理工大学

Dates

Publication Date

20260505

Application Date

20230725

Claims (5)

1. 1. The preparation method of the composite Li-Ca-Ce-LSX hydrophobic molecular sieve is characterized by comprising the following specific steps: Step 1, preparing a Li-Ca-Ce-LSX molecular sieve, namely uniformly mixing a CaCl 2 solution, a CeCl 2 solution and Li-LSX molecular sieve powder according to the mass ratio of Ca, ce ions and lithium ions of 1:1:3, stirring at a constant temperature of 60-90 ℃, carrying out ion exchange reaction for 3 times, carrying out suction filtration after the reaction is finished, washing with water, drying at room temperature, and calcining the solid at 350+/-50 ℃ for 2-3 hours to obtain the Li-Ca-Ce-LSX molecular sieve by activation; step 2, hydrophobic modification, namely mixing a Li-Ca-Ce-LSX molecular sieve with polydimethylsiloxane according to a mass ratio of 1:3 by adopting a vapor deposition method, reacting for 4-7 hours at 200+/-25 ℃, cooling to room temperature after the reaction is finished, taking out a product, and drying to obtain the Li-Ca-Ce-LSX molecular sieve with a hydrophobic surface; Step 3, preparing a composite Li-Ca-Ce-LSX hydrophobic molecular sieve, namely uniformly mixing the Li-Ca-Ce-LSX molecular sieve with hydrophobic surface and attapulgite according to the mass ratio of 3:1, placing the mixture in a mechanical granulator to prepare spheres with the particle size of 0.2-0.4 mm, drying the spheres, and activating the spheres at 100-150 ℃ to prepare the composite Li-Ca-Ce-LSX hydrophobic molecular sieve with the N 2 /O 2 selectivity of 7.18 and the water content of 0.95 percent; The preparation method of the Li-LSX molecular sieve comprises the following steps: (1) Uniformly mixing sodium hydroxide, aluminum hydroxide and deionized water at a low temperature of 50-100 ℃, adding a water glass solution, stirring for 1-2 hours, adding aluminum dioxide, aluminum oxide, sodium potassium, elemental silicon and elemental sodium after the mixture is a viscous solution, stirring at a high speed for 2-4 hours, standing and aging for 6-8 hours at 50-70 ℃ after stopping stirring, crystallizing for 6-8 hours at 80-100 ℃, carrying out suction filtration, washing and drying at 80-100 ℃ to obtain the LSX molecular sieve, wherein the molar ratio of SiO 2 :Al 2 O 3 =5.0-10.0:1 and NaK:Na:Si=5-10:4-9:1-5; (2) The preparation method of the Li-LSX hydrophobic molecular sieve comprises the steps of placing the LSX molecular sieve in a muffle furnace, heating to 100 ℃ at a step length of 10 ℃ per minute for 1-2 hours, continuously heating to 400 ℃ at a step length of 10 ℃ per minute for 1-2 hours, adding the activated LSX molecular sieve into an aqueous solution of Li 2 SO 4 according to a ratio of the mass of the LSX molecular sieve to the volume of Li 2 SO 4 solution of 1:10-30, then adjusting the pH of the solution to 9 by using LiOH, and carrying out ion exchange reaction for 1-5 hours at 80-100 ℃ to obtain the Li-LSX molecular sieve.
2. 2. The method according to claim 1, wherein in the step 1, the concentration of the CaCl 2 concentration solution or the CeCl 2 concentration solution is 0.4. 0.4 mol/L.
3. 3. The preparation method according to claim 1, wherein in the step 3, the drying temperature is 100 ℃, and the drying time is 2-4 hours.
4. 4. A composite Li-Ca-Ce-LSX hydrophobic molecular sieve made according to any one of the preparation methods of claims 1-3.
5. 5. The use of the composite Li-Ca-Ce-LSX hydrophobic molecular sieve of claim 4 in the preparation of an adsorption catalyst, a heavy metal ion adsorbent or a concrete additive.

Description

Composite Li-Ca-Ce-LSX hydrophobic molecular sieve, preparation method and application thereof Technical Field The invention belongs to the technical field of pressure swing adsorption molecular sieve materials, and relates to a composite Li-Ca-Ce-LSX hydrophobic molecular sieve, a preparation method and application thereof. Background The pressure swing adsorption (Pressure Swing Adsorption is abbreviated as PSA) has the advantages of flexibility, convenience, low investment, low energy consumption, good performance, simple process flow, high automation degree and the like, and is widely applied to the application field of small and medium-scale industrial oxygen enrichment in recent years, and further expands to industries such as wastewater treatment, paper industry, medicine, home health care and the like. The technical core of pressure swing adsorption oxygen production is an adsorbent, and the adsorption separation performance of the adsorbent directly determines the energy consumption, the volume, the service life and the like of an oxygen production device, so that the research on efficient oxygen production adsorbent is always the core direction of pressure swing adsorption oxygen production research. According to the statistics of International consultation company TechNavio, the market capacity of the worldwide market molecular sieve adsorbent is increased to 20.10 hundred million dollars by 2023, and compared with the 2018 composite growth rate, the worldwide market molecular sieve adsorbent has 6.08 percent, and has a steadily increasing trend. In the field of industrial oxygen production, along with the great popularization of energy-saving and consumption-reducing technologies and the continuous improvement of environmental protection requirements, the industrial oxygen market is continuously expanded, the demand of enterprises on oxygen production molecular sieves is very large, and a larger growth space is brought to molecular sieve adsorbents. Meanwhile, with the improvement of the living standard of people, people pay more attention to the health of people, wherein oxygen therapy and oxygen health care are gradually accepted and promoted as a new technology for enhancing physique and preventing diseases. Under the support of huge old people, high-intensity brain labor people, high-altitude people and the like, the gradual popularization of medical oxygenerators and household oxygenerators creates huge market space for medical health-care oxygen-producing molecular sieves. In addition, there are many respiratory disease patients in the society at present, and there are many asthma patients, if they breathe hard in home, the problem of oxygen deficiency can be solved by timely using the oxygenerator. The development of molecular sieves for the production of oxygen is therefore very important. The conventional adsorbents for pressure swing adsorption oxygen production at present are mainly X-type molecular sieves, such as Li-LSX and Ca-LSX molecular sieves, but have the following main problems that (1) the oxygen-nitrogen separation coefficient is low, the energy consumption for preparing unit oxygen is high, (2) the influence of water and carbon dioxide in the environment on the performance of the adsorbent is large, and (3) when the adsorbent is applied to small portable oxygen production equipment, the bulk density of large-particle materials is low, so that the high efficiency and the high oxygen concentration of the oxygen production equipment are influenced. Disclosure of Invention The invention aims to provide a composite Li-Ca-Ce-LSX hydrophobic molecular sieve with strong adsorption capacity and large separation coefficient, a preparation method and application thereof. The invention takes a lithium-exchanged low-silicon aluminum X-type zeolite molecular sieve (Li-LSX) as a raw material, combines a forming technology and a lithium exchange technology, further uses Ca and Ce for modification, and synthesizes the composite Li-Ca-Ce-LSX hydrophobic molecular sieve by adopting an aqueous solution exchange method. The molecular sieve has higher polarizability and stronger action on nitrogen, thus having high adsorption capacity and nitrogen-oxygen separation coefficient on nitrogen, having certain hydrophobicity, improving the sensitivity of the molecular sieve to environment and prolonging the service life of the molecular sieve. The technical scheme for realizing the purpose of the invention is as follows: The preparation method of the composite Li-Ca-Ce-LSX hydrophobic molecular sieve comprises the following specific steps: Step 1, preparing a Li-Ca-Ce-LSX molecular sieve, namely uniformly mixing CaCl 2 solution, ceCl 2 solution and Li-LSX molecular sieve powder according to the mass ratio of Ca, ce ions and lithium ions of 1:1:3-4, stirring at a constant temperature of 60-90 ℃, carrying out ion exchange reaction, filtering, washing with water, drying at room temperature, and calcinin