阅读说明：本技术 一种基于中空MOFs材料的低阻高选择性混合基质膜的制备方法 (Preparation method of low-resistance high-selectivity mixed matrix membrane based on hollow MOFs (metal-organic frameworks) material ) 是由 郑文姬 丁锐 贺高红 代岩 焉晓明 阮雪华 杨凯 于 2020-05-20 设计创作，主要内容包括：本发明公开了一种基于中空MOFs材料的低阻高选择性混合基质膜的制备方法,属于膜分离技术领域。本发明首先使用纳米尺寸的羧基化聚苯乙烯作为硬模板,使得MOFs在聚苯乙烯表面生长,通过DMF蚀刻制得纳米级的中空MOFs微球,使用制备的中空MOFs材料与聚合物基质共混制备混合基质膜。所述制备方法使用纳米级的中空MOFs为填料,纳米尺寸的MOFs材料有助于提高MOFs与基质之间的相容性,从而制备无缺陷的混合基质膜,提高选择性；另外,中空结构的存在,能够有效的减小混合基质膜的传质距离,从而降低膜的传质阻力,提高气体渗透速率。(The invention discloses a preparation method of a low-resistance high-selectivity mixed matrix membrane based on a hollow MOFs material, belonging to the technical field of membrane separation. According to the preparation method, firstly, nano-sized carboxylated polystyrene is used as a hard template, MOFs grows on the surface of the polystyrene, nano-scale hollow MOFs microspheres are prepared by DMF etching, and the prepared hollow MOFs material is blended with a polymer matrix to prepare the mixed matrix membrane. The preparation method uses nano-scale hollow MOFs as a filler, and the nano-scale MOFs material is beneficial to improving the compatibility between the MOFs and a matrix, so that a defect-free mixed matrix membrane is prepared, and the selectivity is improved; in addition, the existence of the hollow structure can effectively reduce the mass transfer distance of the mixed matrix membrane, thereby reducing the mass transfer resistance of the membrane and improving the gas permeation rate.)

1. A preparation method of a low-resistance high-selectivity mixed matrix membrane based on a hollow MOFs material is characterized by comprising the following steps:

(1) the nanometer hollow MOFs material is obtained by a template method:

polymerizing styrene and acrylic acid by an emulsion polymerization method to synthesize nano-sized polystyrene microspheres with surfaces rich in carboxyl, coating MOFs materials on the surfaces of the polystyrene microspheres by a water bath method, and etching the polystyrene microspheres coated with the MOFs materials by using a solvent A to form nano-scale hollow MOFs microsphere materials;

(2) film preparation:

adding a nano-scale hollow MOFs microsphere material into the matrix B solution, stirring and ultrasonically treating the mixture to disperse the hollow MOFs microsphere material into the matrix B solution, pouring the prepared membrane casting solution into a watch glass, and casting the membrane into a drying oven at 40-60 ℃ to form a membrane.

2. The preparation method according to claim 1, wherein polystyrene microspheres are used as a hard template to prepare core-shell MOFs, and a solvent A is used to dissolve polystyrene to prepare a hollow structure, so as to obtain the hollow MOFs microsphere material.

3. The method as claimed in claim 1 or 2, wherein the diameter of the hollow MOFs microsphere material is 108-140 nm.

4. The process according to claim 1 or 2, wherein the solvent A is DMF or THF; the matrix B is polyether copolyamide, polysulfone, polyimide or polydimethylsiloxane.

5. The method according to claim 1 or 2, wherein said MOFs are ZIF-8, ZIF-7, ZIF-90, HKUST-1 or NH₂-MIL-101(Cr)。

6. The method according to claim 1 or 2, wherein the concentration of the substrate B is 3 to 8 wt.%.

7. The production method according to claim 1 or 2, wherein the volume ratio of styrene to acrylic acid is 9:1 to 1: 1.

8. The method according to claim 1 or 2, wherein the water bath temperature is 70 ℃ and the water bath time is 30 min; the drying time in the oven is 12-24 h.

9. The preparation method according to claim 1 or 2, wherein the thickness of the MOFs material on the surface of the polystyrene microsphere is 4-20 nm.

10. The method according to claim 1 or 2, characterized in that the hollow MOFs microsphere material is 5%, 10% or 15% by mass of the matrix B.

Technical Field

The invention belongs to the technical field of membrane separation, and particularly relates to a preparation method of a low-resistance high-selectivity mixed matrix membrane based on a hollow MOFs material.

Background

Carbon dioxide, the most prominent greenhouse gas in the greenhouse effect, has been studied extensively for its isolation and capture. At present, the separation of carbon dioxide mainly comprises an absorption method, an adsorption method and a membrane separation method. The membrane separation technology has the advantages of low energy consumption, easy operation, easy coupling and the like, and becomes a research hotspot for carbon dioxide separation.

Gas membranes mainly include inorganic membranes and organic membranes, among which organic membranes are widely used for hydrogen separation, oxygen and nitrogen enrichment and natural gas purification, but Robeson as early as 1991 proposed that the separation performance of polymer membranes is limited by the inherent performance of the membranes, that the polymer membranes have a trade-off effect in selectivity and permeability, i.e., selectivity and permeability are difficult to combine, and that inorganic membranes, although having high gas selectivity, are relatively fragile, and expensive to manufacture and difficult to produce on a large scale.

The mixed matrix membrane combines the organic membrane and the inorganic particles, has the advantages of the organic membrane and the inorganic membrane, and improves the gas permeability while maintaining high selectivity of the membrane to gas, thereby improving the gas separation performance of the membrane. Among the existing various inorganic fillers, MOFs materials are widely applied to mixed matrix membranes due to the advantages of large specific surface area, rich pore structure, good compatibility with a matrix, strong modification and the like. However, despite the abundance of channels in the MOFs, the incorporation of the MOFs still has a large gas transport resistance, which hinders the increase of the gas permeation rate, and the MOFs still has a compatibility problem with the substrate, which is likely to generate defects during the film formation process, so that the selectivity is reduced. Therefore, the preparation of the mixed matrix membrane with low gas transmission resistance and high selectivity is extremely important for improving the membrane performance.

Disclosure of Invention

Based on the problems in the prior art, the invention aims to prepare a low-resistance high-selectivity mixed matrix membrane based on hollow MOFs materials.

The technical scheme of the invention is as follows:

a preparation method of a low-resistance high-selectivity mixed matrix membrane based on a hollow MOFs material comprises the following steps:

a preparation method of a low-resistance high-selectivity mixed matrix membrane based on a hollow MOFs material comprises the steps of preparing core-shell MOFs by using polystyrene microspheres as a hard template, dissolving polystyrene by using a solvent A, and manufacturing a hollow structure to obtain the hollow MOFs microsphere material; the method comprises the following specific steps:

(1) the nanometer hollow MOFs material is obtained by a template method:

polymerizing styrene and acrylic acid by an emulsion polymerization method to synthesize nano-sized polystyrene microspheres with surfaces rich in carboxyl, coating MOFs materials on the surfaces of the polystyrene microspheres by a water bath method, and etching the polystyrene microspheres coated with the MOFs materials by using a solvent A to form the nano-scale hollow MOFs microsphere materials.

The volume ratio of the styrene to the acrylic acid is 9:1-1: 1.

The water bath temperature is 70 ℃, and the water bath time is 30 min.

The mass percentage of the hollow MOFs microsphere material in the matrix B is 5%, 10% or 15%.

The diameter of the hollow MOFs microsphere material is 108-140 nm.

The thickness of the MOFs material on the surface of the polystyrene microsphere is 4-20 nm.

The solvent A is DMF or THF.

(2) Film preparation:

adding a nano-scale hollow MOFs microsphere material into the matrix B solution, stirring and ultrasonically treating the mixture to disperse the hollow MOFs microsphere material into the matrix B solution, pouring the prepared membrane casting solution into a watch glass, and casting the membrane into a drying oven at 40-60 ℃ to form a membrane.

The substrate B is polyether copolyamide, polysulfone, polyimide or polydimethylsiloxane.

The MOFs material is ZIF-8, ZIF-7, ZIF-90, HKUST-1 or NH₂-MIL-101(Cr)。

The concentration of the matrix B is 3-8 wt.%.

The drying time in the oven is 12-24 h.

The invention has the beneficial effects that: the mixed matrix membrane uses nano-sized hollow MOFs as a filler, and the nano-sized MOFs material can improve the compatibility between the MOFs and the matrix, so that a defect-free mixed matrix membrane is prepared, and the selectivity is improved; meanwhile, the special hollow structure is utilized, the mass transfer distance of the mixed matrix membrane can be effectively reduced, so that the mass transfer resistance of the membrane is reduced, and the gas permeation rate is improved.

Drawings

FIG. 1 is a scanning electron micrograph of hollow MOFs microspheres.

FIG. 2 is a transmission electron micrograph of hollow MOFs microspheres.

FIG. 3 is a cross-sectional electron micrograph of a hollow ZIF-8/Pebax membrane.

Detailed Description

The following further describes a specific embodiment of the present invention with reference to the drawings and technical solutions.