阅读说明：本技术 一种精确筛分气体分子对的混合基质膜的制备方法 (Preparation method of mixed matrix membrane for accurately screening gas molecule pairs ) 是由 郑文姬 郭自兴 王秋晨 焉晓明 代岩 贺高红 于 2019-09-03 设计创作，主要内容包括：本发明公开了一种精确筛分气体分子对的混合基质膜的制备方法,属于膜分离技术领域。将活化后的MOF颗粒分散于离子液体溶液中,再使溶液中的低沸点溶剂充分挥发得到MOF/离子液体复合物。选用溶剂洗掉复合物表面离子液体,得到类核壳结构的不同离子液体含量复合物,再将其混入聚合物溶液,浇铸成膜。本方法从填充物有序调控填料孔道尺寸的角度可将MOF孔径修饰到一定范围内,实现了精确筛分具有不同尺寸的气体分子对,在其他物化性质相近而尺寸有差异的气体对分离过程中,提供一种新颖可行的思路。(The invention discloses a preparation method of a mixed matrix membrane for accurately screening gas molecule pairs, belonging to the technical field of membrane separation. Dispersing the activated MOF particles in an ionic liquid solution, and fully volatilizing a low-boiling-point solvent in the solution to obtain the MOF/ionic liquid compound. And (3) selecting a solvent to wash away ionic liquid on the surface of the compound to obtain compounds with different ionic liquid contents of the similar core-shell structure, mixing the compounds into a polymer solution, and casting to form a film. According to the method, the pore size of the MOF can be modified to a certain range from the angle of orderly regulating and controlling the pore size of the filler by the filler, so that the gas molecule pairs with different sizes are accurately screened, and a novel and feasible thought is provided in the separation process of other gas pairs with similar physicochemical properties and different sizes.)

1. A preparation method of a mixed matrix membrane for precisely screening gas molecule pairs is characterized by comprising the following steps:

selecting room temperature ionic liquid RTILs with different sizes and different physicochemical properties, dispersing the RTILs and filler MOF activated at 150 ℃ in a solvent A, naturally volatilizing the solvent A to obtain RTILs/MOF compounds, washing free ionic liquid on the surface of the prepared compounds by using a solvent B to obtain RTILs/MOF compounds with different ionic liquid contents, marking as IL @ MOF, mixing the RTILs/MOF compounds into a polymer solution, and casting to form a film.

2. The preparation method according to claim 1, wherein the mass ratio of the RTILs to the MOF is 0.5-5.

3. The method according to claim 1 or 2, wherein the polymer is a polyether copolyamide 1657, a polyimide, a polyetherimide, a polyethersulfone or a polydimethylsiloxane;

the polymer dosage is determined according to the formula:

4. the method according to claim 1 or 2, wherein the room temperature ionic liquid is 1-ethyl-3-methyl hexafluorophosphate [ Emim ™ ]][PF₆]1-butyl-3-methylhexafluorophosphate [ Bmim ]][PF₆]1-hexyl-3-methylhexafluorophosphate [ Hmim ]][PF₆]1-butyl-3-methyl bis (trifluoromethanesulfonyl) imide salt [ Bmim ]][Tf₂N]Or 1-ethyl-3-methyl bis (trifluoromethanesulfonimide) salt [ Emim ]][Tf₂N]。

5. The method according to claim 3, wherein the room temperature ionic liquid is 1-ethyl-3-methyl hexafluorophosphate [ Emim][PF₆]1-butyl-3-methylhexafluorophosphate [ Bmim ]][PF₆]1-hexyl-3-methylhexafluorophosphate [ Hmim ]][PF₆]1-butyl-3-methyl bis (trifluoromethanesulfonyl) imide salt [ Bmim ]][Tf₂N]Or 1-ethyl-3-methyl bis (trifluoromethanesulfonimide) salt [ Emim ]][Tf₂N]。

6. The preparation method according to claim 1, 2 or 5, wherein the MOF is an MOF with a cage-pore structure, and is ZIF-71, ZIF-67, ZIF-7, ZIF-8, ZIF-90, ZIF-95 or ZIF-100.

7. The preparation method of claim 3, wherein the MOF is an MOF with a cage-pore structure, and is ZIF-71, ZIF-67, ZIF-7, ZIF-8, ZIF-90, ZIF-95 or ZIF-100.

8. The preparation method according to claim 4, wherein the MOF is an MOF with a cage-pore structure, and is ZIF-71, ZIF-67, ZIF-7, ZIF-8, ZIF-90, ZIF-95 or ZIF-100.

9. The method according to claim 1, 2, 5, 7 or 8, wherein the solvent A is acetone, chloroform, diethyl ether or dichloromethane;

the solvent B is N, N-dimethylformamide, N-dimethylacetamide or dimethyl sulfoxide.

10. The method according to claim 6, wherein the solvent A is acetone, chloroform, diethyl ether or dichloromethane;

the solvent B is N, N-dimethylformamide, N-dimethylacetamide or dimethyl sulfoxide.

Technical Field

The invention belongs to the technical field of membrane separation, and particularly relates to a method for preparing a mixed matrix membrane capable of accurately screening gas molecule pairs with different sizes.

Background

CO₂Gas capture has become one of the international problems that human society in the 21 st century is urgently required to solve. CO 2₂The global warming is aggravated by an excessive concentration in the atmosphere, and in addition, CO₂The common associated gas of energy gas such as natural gas, coal field gas, methane and the like can cause pipeline corrosion in the transportation process if not removed in advance, and can also reduce the heat value of fuel to influence the energy supply efficiency. Traditionally to CO₂The separation of (2) mainly adopts pressure swing adsorption, chemical absorption, low-temperature distillation and other methods. The gas membrane separation technology is applicable to CO₂Compared with the traditional separation method, the novel trapping separation technology has the advantages of no phase change, no regeneration process of a mass separating agent, mild process conditions, low operation cost, small occupied area and the like, and is rapidly developed in recent years. Membrane materials are a key part of membrane separation technology. Use of conventional polymer membrane materials for CO₂During separation, the problems of low separation performance, serious plasticization, no high temperature and high pressure resistance and the like exist, and CO is restricted₂The industrialization of membrane separation is developed. Therefore, the research on membrane materials that can simultaneously satisfy the separation requirements and the mechanical property requirements is the focus of the field.

Mixed matrix membranes (mixedmatrixmambranes) are novel materials that combine the high separation performance of inorganic membranes with the mechanical properties and cost advantages of polymer membranes to meet the requirements of the membrane separation industry in the future. The selection of the inorganic filler is critical to the preparation of high performance mixed matrix membranes. Metal-organic framework compounds (MOFs) exhibit better interfacial compatibility in film materials due to their partially organic nature. The pore channels of the MOFs are formed by assembling metal ions and organic ligands together, and the types of the MOFs are continuously updated due to the functional diversity of the organic ligands, so that the number of the MOFs reaches tens of thousands. However, the pore size of the MOFs is generally larger than the gas molecular dynamics size, and cannot be ideally between two gases to be separated, so that the sieving effect of the filler cannot be fully exerted. Although the pore structure can be modified by methods such as metal ion replacement, ligand modification and the like, the operation difficulty is high, and the actual requirements cannot be met.

Disclosure of Invention

Based on the problems in the prior art, the invention aims to prepare a mixed matrix membrane capable of accurately screening gas molecule pairs with different sizes.

The technical scheme of the invention is as follows:

a preparation method of a mixed matrix membrane for precisely screening gas molecule pairs comprises the following steps:

selecting Room Temperature Ionic Liquids (RTILs) with different sizes and different physicochemical properties, dispersing the RTILs and filler MOF powder activated by an oven at 150 ℃ in a solvent A, obtaining an RTILs/MOF compound by adopting a natural volatilization method of the solvent A, washing free ionic liquid on the surface of the prepared compound by adopting a solvent B to obtain the RTILs/MOF compound with different ionic liquid contents, marking as IL @ MOF, mixing the RTILs/MOF compound with a polymer solution, and casting to form a film.

The mass ratio of the RTILs to the MOF is 0.5-5;

the room-temperature ionic liquid is 1-ethyl-3-methyl hexafluorophosphate [ Emim][PF₆]1-butyl-3-methylhexafluorophosphate [ Bmim ]][PF₆]1-hexyl-3-methylhexafluorophosphate [ Hmim ]][PF₆]1-butyl-3-methyl bis (trifluoromethanesulfonyl) imide salt [ Bmim ]][Tf₂N]Or 1-ethyl-3-methyl bis (trifluoromethanesulfonimide) salt [ Emim ]][Tf₂N]。

The MOF is an MOF with a cage-pore structure and comprises ZIF-71, ZIF-67, ZIF-7, ZIF-8, ZIF-90, ZIF-95 or ZIF-100.

The solvent A is acetone, chloroform, diethyl ether or dichloromethane.

The solvent B is N, N-dimethylformamide, N-dimethylacetamide or dimethyl sulfoxide.

The polymer is polyether copolyamide 1657(Pebax1657), polyimide, polyetherimide, polyethersulfone or polydimethylsiloxane.

The polymer dosage is determined according to the formula:

the invention has the beneficial effects that: in the ionic liquid @ MOFs compound prepared by the invention, the content range of the ionic liquid is 3% -20%, and after the ionic liquid @ MOFs compound is mixed into Pebax1657 to prepare a mixed matrix membrane, under the test conditions of 25 ℃ and 0.3MPa, CO is added₂Compared with a pure Pebax membrane, the permeability coefficient is improved by 92.1 percent and can reach 115Barrer, CO₂/N₂The separation selectivity is improved by 54.5 percent to 85 percent, and the CO content is improved by over 2008₂/N₂Roberson upper limit.

Drawings

FIG. 1 is example 1, ZIF-8, [ Bmim ]][PF₆]@ ZIF-8 Complex, [ Bmim ]][PF₆]Thermogravimetry curve of (a).

FIG. 2 is example 2, ZIF-8, [ Bmim ]][PF₆]@ ZIF-8 Complex, [ Bmim ]][PF₆]Thermogravimetry curve of (a).

FIG. 3 is example 3, ZIF-8, [ Bmim ]][Tf₂N]@ ZIF-8 Complex, [ Bmim ]][Tf₂N]Thermogravimetry curve of (a).

FIG. 4 is example 4, ZIF-71, [ Emim ]][Tf₂N]@ ZIF-71 Complex, [ Emim][Tf₂N]Thermogravimetry curve of (a).

Detailed Description

The following further describes the specific embodiments of the present invention in combination with the technical solutions.