CN-122006495-A - Molecular sieve membrane based on nutrient-rich liquid and preparation method and application thereof

CN122006495ACN 122006495 ACN122006495 ACN 122006495ACN-122006495-A

Abstract

The invention provides a molecular sieve membrane based on nutrient-rich liquid, and a preparation method and application thereof, and belongs to the technical field of inorganic molecular sieve membrane materials and membrane separation. The method comprises the steps of constructing a high-nutrition reaction system, accurately regulating and controlling the composition of a silicon source and an alkali source, realizing the rapid nucleation and the efficient growth of molecular sieve crystals in a short time, preparing high-crystallinity molecular sieve seed crystals, uniformly loading the seed crystals on the surface of a porous support body to form a continuous compact seed crystal layer, and rapidly constructing a molecular sieve membrane with complete structure and controllable thickness by utilizing the eutrophic reaction liquid for short-time hydrothermal growth. The preparation method provided by the invention is simple and efficient, effectively shortens the preparation period of the molecular sieve membrane, promotes the intergrowth and compact accumulation among crystals, and obviously reduces the generation of membrane defects. The prepared molecular sieve membrane has excellent separation performance in the pervaporation separation application of water and low molecular weight and low polarity organic solvents (such as acetonitrile, ethanol, acetone, isopropanol, tetrahydrofuran, n-butanol, tertiary butanol and dimethyl carbonate), and has good industrial application prospect.

Inventors

WANG QING
CHEN HUIYUAN
LIU YINGYING
XU NONG
LIU JIAO
YANG WEI
ZHOU RONGFEI
XING WEIHONG

Assignees

合肥大学

Dates

Publication Date: 20260512
Application Date: 20260205

Claims (10)

1. The preparation method of the molecular sieve membrane based on the nutrient-rich liquid is characterized by comprising the following specific steps: S1, preparing a first reaction solution, namely uniformly mixing an aluminum source, a silicon source, a first inorganic base, a second inorganic base, an organic template agent and deionized water according to a molar ratio to form a solution, and continuously aging at room temperature to prepare the first reaction solution; S2, preparing molecular sieve seed crystals, namely transferring the first reaction solution prepared in the step S1 into an autoclave for hydrothermal synthesis reaction, after the reaction is finished, extracting and cooling the reaction kettle, centrifugally separating reaction products, washing the reaction products with deionized water to be neutral, and freeze-drying the reaction products to prepare the original molecular sieve seed crystals; s3, template removing agent and ball milling treatment, namely placing the original molecular sieve seed crystal obtained in the S2 into a muffle furnace for calcination to obtain a first-size seed crystal; S4, preparing support seed crystals, namely respectively adding the molecular sieve seed crystals with the two sizes prepared in the step S3 into deionized water to prepare a first-size seed crystal solution and a second-size seed crystal solution with the concentration of 0.25-1wt%, sequentially and uniformly coating the two seed crystals on a porous support, and forming a seed crystal layer on the surface of the support to prepare the seed crystal support; And S5, preparing a molecular sieve membrane, namely uniformly mixing an aluminum source, a silicon source, a first inorganic base, a second inorganic base and deionized water according to a molar ratio to obtain a mixed solution, continuously stirring the mixed solution at room temperature to obtain a second reaction solution rich in nutrition, placing the second reaction solution and the seed crystal support prepared in the step S4 in a reaction kettle, performing hydrothermal synthesis reaction in an oven, cooling the reaction kettle after the reaction is finished, removing, cleaning and drying the membrane, and obtaining the molecular sieve membrane.
2. The method for preparing a nutrient solution-based molecular sieve membrane according to claim 1, wherein in S1 and S5, the aluminum source is one of sodium aluminate, sodium metaaluminate, aluminum sulfate octadecanoate, and aluminum isopropoxide, the silicon source is one of silica sol, sodium silicate, and ethyl orthosilicate, the first inorganic base is sodium hydroxide, and the second inorganic base is at least one of potassium hydroxide, lithium hydroxide, and aluminum hydroxide. .
3. The method for preparing a nutrient-rich solution-based molecular sieve membrane according to claim 2, wherein in S1, the molar ratio of the aluminum source to the silicon source to the first inorganic base to the second inorganic base to the organic template to deionized water is 1 (15-21): (3.2-5.2): 3 (1.5-3): (163-263), wherein the aluminum source is calculated as Al 2 O 3 , the silicon source is calculated as SiO 2 , the first inorganic base is calculated as Na 2 O, the second inorganic base is calculated as OH - , and the organic template is calculated as TMAOH.
4. The method for preparing a nutrient-rich solution-based molecular sieve membrane according to claim 2, wherein in S5, the molar ratio of the aluminum source, the silicon source, the first inorganic base, the second inorganic base and deionized water is 1 (15-21): 3.2-5.2): 3 (163-263), wherein the aluminum source is calculated as Al 2 O 3 , the silicon source is calculated as SiO 2 , the first inorganic base is calculated as Na 2 O, and the second inorganic base is calculated as OH - .
5. The method for preparing a nutrient-rich solution-based molecular sieve membrane according to claim 1, wherein the hydrothermal synthesis reaction in S2 is performed under the conditions of 80-120 ℃ for 36-60 hours.
6. The method for preparing a nutrient-rich solution-based molecular sieve membrane according to claim 1, wherein in S3, the calcination condition is calcination at 450-650 ℃ for 4-8 hours, the average size of the first-size seeds obtained after calcination is 1.1 μm, the average size of the second-size seeds obtained after ball milling is 0.25 μm, and the ball milling condition is ball milling at 450r/min for 3 hours.
7. The method for preparing a nutrient solution-based molecular sieve membrane according to claim 1, wherein in S4, the concentration of both seed solutions is 0.5 wt%, both ends of the porous support are plugged with silicone plugs, and the porous support having an average pore size of 1-2 μm is immersed in the seed solution for coating by dip coating for a coating time of 60. 60S.
8. The method for preparing a nutrient-rich solution-based molecular sieve membrane according to claim 1, wherein in S5, the hydrothermal synthesis reaction is performed under the condition of hydrothermal synthesis in an oven at 140-160 ℃ for 2-6 hours.
9. A molecular sieve membrane based on a nutrient rich solution, characterized in that the molecular sieve membrane is prepared by the preparation method of any one of claims 1-8, and the prepared molecular sieve seed crystal and molecular sieve membrane have a T-type zeolite structure.
10. Use of the molecular sieve membrane of claim 9 for separating water/isopropanol, water/acetone, water/ethanol, water/dimethyl carbonate, water/acetonitrile, water/tetrahydrofuran, water/n-butanol, water/t-butanol.

Description

Molecular sieve membrane based on nutrient-rich liquid and preparation method and application thereof Technical Field The invention relates to the technical field of inorganic membrane materials and preparation, in particular to a molecular sieve membrane based on nutrient-rich liquid, a preparation method thereof and application thereof in separating water/isopropanol, water/acetone, water/ethanol, water/dimethyl carbonate, water/acetonitrile, water/tetrahydrofuran, water/n-butanol and water/tertiary butanol. Background The membrane separation is a technical route for realizing component separation based on the difference of the transmission behaviors of substances in the membrane, and the process has the characteristics of low energy consumption, mild running condition, compact equipment structure, easy realization of continuous operation and the like, and has good application potential in the fields of chemical production, energy conversion, environmental treatment and the like. The structural characteristics, pore channel properties and chemical stability of the membrane material are key factors affecting the membrane separation performance. Compared with a high molecular film, the inorganic film can still keep better structural stability and service life in high temperature, strong solvent and corrosive environment, wherein the molecular sieve film can realize accurate sieving on molecular scale due to the regular crystal structure and the highly uniform pore canal size, thereby becoming an important development direction of high-performance film materials gradually. The T-shaped molecular sieve is an aluminosilicate material with a specific pore structure, has an effective pore diameter of 0.36 nm multiplied by 0.51 nm, is suitable for the selective separation of a water/organic molecular system, and has potential application advantages in the fields of organic solvent dehydration, small molecule separation and the like. Meanwhile, the molecular sieve generally shows certain hydrophilicity and better chemical stability, so that the molecular sieve has application possibility in a complex system. However, since the T-type molecular sieve belongs to an aluminum-rich molecular sieve, problems such as uneven distribution of silicon and aluminum, insufficient binding force of crystal grains and the like easily occur in the crystal growth process, thereby forming grain boundary defects or non-selective mass transfer channels in the membrane layer, and further affecting the separation selectivity and long-term operation stability of the membrane. The existing preparation method of the T-shaped molecular sieve membrane mostly adopts a hydrothermal in-situ synthesis or seed crystal induction growth process, but the problems that the nutrition level of a reaction system is limited, the crystal nucleation and growth rate is slow, the film forming period is long, the thickness of the membrane layer is difficult to accurately regulate and control, the surface uniformity is insufficient, defects are difficult to effectively inhibit and the like generally exist. In addition, part of the preparation methods depend on mineralizers or need to be subjected to high-temperature post-treatment steps, so that not only are the energy consumption and the process complexity increased, but also structural defects such as film cracking, delamination and the like are easily caused by overgrowth of crystals and thermal stress, and the overall integrity and the service life of the film are influenced. Therefore, on the premise of ensuring the structural integrity of the membrane layer, the rapid construction, the thickness-controllable growth and the effective defect inhibition of the T-shaped molecular sieve membrane are realized by regulating the composition of a reaction system and the growth process of crystals, and the key technical problem to be solved in the field is still needed. Disclosure of Invention (One) solving the technical problems Aiming at the problems of low film forming rate, long preparation period, difficult accurate regulation and control of film thickness and structure, grain boundary defects, insufficient process repeatability and stability and the like commonly existing in the existing T-shaped molecular sieve film preparation process, the invention provides a molecular sieve film based on a nutrient-rich solution and a preparation method thereof. According to the invention, by constructing a high-nutrition reaction system and cooperating with multi-size high-activity seed crystal to induce growth, the rapid nucleation and controllable epitaxial growth of the T-shaped molecular sieve crystal are realized in a shorter hydrothermal time, so that the problems of slow growth, discontinuous structure and difficult defect inhibition of a film layer in the traditional method are solved, and the preparation of the T-shaped molecular sieve film with rapid film layer construction, controllable thickness, compact str