CN-117398854-B - Long-range ordered separation membrane, preparation method and application thereof

Abstract

The invention relates to the technical field of CO 2 trapping, in particular to a long-range ordered separation membrane, a preparation method and application thereof. The invention prepares a long-range (5-6 cm) continuous layered graphene oxide skeleton by adopting a wedge-shaped die with a proper angle and a freeze drying method to ensure the separation effect of the film, and simultaneously adopts a controllable hydrothermal reduction method to realize the precise regulation and control of the reduction degree of the graphene oxide skeleton by regulating and controlling the reduction temperature, thereby controlling the interlayer spacing, improving the separation effect and adopting epoxy resin to play a mechanical fixing role. In addition, the hydrothermal reduction reaction does not need to additionally introduce a reducing agent harmful to the environment, and is simple, convenient, quick and environment-friendly. The finally prepared long-range ordered separation membrane is a multi-transmission channel long-range ordered separation membrane, is suitable for high-pressure and low-pressure environments, and can be used for separating CO 2 in CO 2 /N 2 and separating CO 2 in CO 2 /H 2 .

Inventors

• WU TONG
• WANG QI
• LI XU
• LIU LIANBO
• GAO SHIWANG
• HE ZHONG
• CHENG ACHAO
• LUO LIQIANG
• QIN SHENGHUI

Assignees

• 中国华能集团清洁能源技术研究院有限公司

Dates

Publication Date

20260505

Application Date

20231017

Claims (10)

1. 1. The preparation method of the long-range ordered separation membrane comprises the following steps: A) Pouring the graphene oxide dispersion liquid into a wedge-shaped die with an angle of 15-30 degrees, freezing, and then drying in vacuum to obtain a layered graphene oxide skeleton; B) Carrying out hydrothermal reaction on the layered graphene oxide skeleton at 100-175 ℃ to obtain a reduced layered graphene oxide skeleton; C) Immersing the reduced lamellar graphene oxide skeleton into a resin solution, and curing after vacuum defoaming to obtain a graphene oxide-resin blank; The resin solution comprises epoxy resin and a coagulant; d) And thinning and polishing the graphene oxide-resin blank to obtain the long-range ordered separation membrane.
2. 2. The method of preparing a graphene oxide dispersion according to claim 1, comprising the steps of: a) Mixing first concentrated sulfuric acid, potassium persulfate, phosphorus pentoxide and graphite powder, and reacting at 75-85 ℃ to obtain graphite pre-oxide; b) Uniformly mixing the second concentrated sulfuric acid, the graphite pre-oxide, the potassium permanganate and the sodium nitrate at 5-20 ℃, reacting for 1-5 hours at 30-35 ℃, adding deionized water for dilution, continuously reacting for 1-5 hours at 30-35 ℃, and adding 30-35 wt% of hydrogen peroxide to terminate the reaction to obtain the graphite oxide; c) Washing graphite oxide with acid, washing with water to neutrality, ultrasonically dispersing the graphite oxide into water, and centrifuging to obtain graphene oxide dispersion liquid; the concentration of the graphene oxide dispersion liquid is 1-3 g/L.
3. 3. The preparation method according to claim 2, wherein in the step a), the mass ratio of the potassium persulfate to the phosphorus pentoxide to the graphite powder is 5-10:5-10:2-10; the dosage ratio of the first concentrated sulfuric acid to the graphite powder is 20-60 mL:2-10 g; After the reaction, the method further comprises: cooling to room temperature, adding deionized water for dilution, carrying out suction filtration, washing to be neutral, and drying to obtain the graphite pre-oxide.
4. 4. The preparation method according to claim 2, wherein in the step b), the mass ratio of the graphite pre-oxide to the potassium permanganate to the sodium nitrate is 2-10:15-25:2-10; the dosage ratio of the graphite pre-oxide to the second concentrated sulfuric acid is 2-10 g/20-250 mL.
5. 5. The method of manufacturing according to claim 1, wherein the method of manufacturing the wedge mold comprises the steps of: Placing the square copper sheet or copper plate on an inclined platform with the gradient of 15-30 degrees, pouring mixed liquid comprising polydimethylsiloxane and curing agent into the freezing container until the frozen surface is just covered, and curing to obtain a wedge-shaped die with the angle of 15-30 degrees; The mass ratio of the polydimethylsiloxane to the curing agent is 8-10:1-2.
6. 6. The method according to claim 1, wherein in the step a), the freezing temperature is-20 to-70 ℃ and the time is 0.5 to 2 hours; the temperature of the vacuum drying is minus 60 to minus 80 ℃ and the time is 12 to 48 hours.
7. 7. The method according to claim 1, wherein in the step C), the volume ratio of the epoxy resin to the coagulant is 1:2-3; The vacuum degree of the vacuum defoaming is-0.08 to-0.1 MPa; the curing time is 12-24 hours.
8. 8. The method according to claim 1, wherein in step D), the thickness of the thinned graphene oxide-resin green body is 0.2 to 2 μm; the polishing includes: polishing the upper and lower surfaces of the thinned graphene oxide-resin blank by adopting metallographic sand paper with the mesh number of 4000 ten thousand; the interlayer spacing of the long-range order separation membrane is
9. 9. The long-range ordered separation membrane produced by the production method according to any one of claims 1 to 8.
10. 10. Use of the long-range ordered separation membrane of claim 9 in the field of CO 2 separation.

Description

Long-range ordered separation membrane, preparation method and application thereof Technical Field The invention relates to the technical field of CO 2 trapping, in particular to a long-range ordered separation membrane, a preparation method and application thereof. Background Reduction of CO 2 is one of the significant challenges facing countries around the world. Currently, the carbon capturing methods with more applications mainly comprise an absorption method, an adsorption method, a cryogenic separation method and the like. The membrane separation method is a novel separation technology which appears in recent decades, and has the advantages of low energy consumption, high selectivity, no phase change, simple and flexible equipment, no secondary pollution and the like, thereby showing good development prospect in the field of CO 2 trapping. The membrane separation process can be applied singly or combined with other separation technologies, and further realizes the efficient separation of CO 2. The two-dimensional graphene-based separation membrane material is taken as a novel nano carbon material, is active in the field of two-dimensional layered materials in recent decades, and mainly comprises a perfect lattice graphene membrane, a nano pore graphene membrane and a graphene oxide membrane. The perfect lattice graphene film occupies the pores of the lattice due to the very dense delocalized pi electron cloud, and is impermeable to all molecules and atoms, so that the perfect lattice graphene film has less application in the separation field. Researchers generally adopt a mode of introducing nano/sub-nano-scale holes with different sizes on the surface of a single-layer graphene film to prepare a nano-pore graphene film, so that the nano-pore graphene film is used for selective separation of molecules with different particle sizes. The group Zhao Yuliang of Chinese academy of sciences designed a series of porous graphene membranes with different pore sizes and shapes through molecular dynamics simulation to separate H 2/N2. It was found that the selectivity and permeability of the membrane can be achieved by controlling the shape and size of the pores such that one hundred percent separation of H 2 from N 2 (gas permeation quantity N 2：H2 =0:10) can be achieved when the pore size is larger than H 2 molecules and smaller than N 2 molecules, and that separation of N 2 from H 2 (gas permeation quantity N 2：H2 =255:39) can be achieved when the pore size continues to increase. The ultra-thin (20 nm) macromolecule functionalized single-layer graphene film is prepared by ion beam bombardment of the Loose Luoshan Federal control project KumarVaroon Agrawal group, so that the ultra-high CO 2/N2 separation performance, namely CO 2 flux 6200GPU and CO 2/N2 separation factor 22.5, is realized, and the highest performance of the non-accelerating transfer film is broken through. however, the current pore-forming technology such as high-energy ion beam bombardment, oxygen plasma etching and the like has high cost, is not mature, and is difficult to avoid the problem that the mechanical strength of the membrane is obviously reduced due to the problems of irregular pore diameter, stress concentration and the like, so that the qualified nano porous graphene product is difficult to prepare in a large scale. The Graphene Oxide (GO) film is a two-dimensional layered film formed by orderly forming single-layer graphene oxide sheets, can screen molecules with different sizes by regulating and controlling the spacing between the sheets, has simple preparation method, low cost and large-scale preparation, and has great application potential in the field of CO 2 separation. The more oxygen-containing functional groups in the sheet layer surface, the larger the interlayer spacing of the graphene oxide is. Under the drying condition, the spacing between the pure graphene oxide sheets isHigher thanThe molecular dynamics diameter of (3) is not ideal for the separation effect of a CO 2/N2、CO2/H2 system. Therefore, there are studies reporting that a reduction method can be employed to reduce the graphene oxide interlayer spacing. For example, hydrazine hydrate or hydroiodic acid is used as a reducing agent to reduce graphene oxide. However, because the reducing capability of hydrazine hydrate or hydroiodic acid is too large, accurate regulation and control of the interlayer spacing are difficult to realize in a wider range, and the interlayer spacing of the graphene oxide film reduced by the hydrazine hydrate or the hydroiodic acid is too small, so that the CO 2 permeability of the graphene oxide film is greatly reduced, and the separation rate is reduced. Or doping graphene oxide to prepare a mixed matrix membrane of graphene oxide, so as to realize modification of the separation membrane, thereby improving the separation effect. The Jin Moqin topic group at Nanjing university of industry introduces GO into the Pebax polymer