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CN-122006514-A - Graphite-phase carbon nitride@nickel-based layered double metal hydroxide composite film and preparation method and application thereof

CN122006514ACN 122006514 ACN122006514 ACN 122006514ACN-122006514-A

Abstract

The invention discloses a graphite phase carbon nitride@nickel base layered double metal hydroxide composite film, a preparation method and application thereof, the composite membrane is formed by in-situ growth of nickel-based layered double hydroxide on the surface of a graphite-phase carbon nitride nano-sheet to construct a composite nano-sheet, and then assembling the composite nano-sheet. The in-situ growth composite strategy adopted by the invention can realize the uniform composite of two components of graphite-phase carbon nitride and nickel-based layered double hydroxide, and form a firm interface bonding effect, so that the microstructure of the composite membrane is effectively regulated and controlled, and the composite membrane has higher hydrogen permeation flux and hydrogen/carbon dioxide separation selectivity.

Inventors

  • XUE JIAN
  • HE KUNYAN
  • MA YING

Assignees

  • 华南理工大学

Dates

Publication Date
20260512
Application Date
20260404

Claims (10)

  1. 1. The preparation method of the graphite-phase carbon nitride@nickel-based layered double metal hydroxide composite film is characterized by comprising the following steps of: (1) Mixing and ball-milling the solid-phase graphite-phase carbon nitride nanosheets with solid-phase alkali, adding deionized water after ball-milling, ball-milling again, dialyzing, centrifuging, and standing to obtain an aqueous solution of the hydroxylated graphite-phase carbon nitride nanosheets; (2) Adding soluble nickel salt into the hydroxylated graphite phase carbon nitride nanosheet aqueous solution obtained in the step (1), and stirring and mixing to obtain a mixed solution; (3) Adding a precipitant into the mixed solution obtained in the step (2) and standing to obtain a hydroxylated graphite phase carbon nitride@nickel-based layered double hydroxide composite material dispersion; (4) And (3) depositing the hydroxylated graphite phase carbon nitride@nickel base layered double-metal hydroxide composite material dispersion liquid obtained in the step (3) on a porous substrate to obtain a graphite phase carbon nitride@nickel base layered double-metal hydroxide composite film.
  2. 2. The method for producing a graphite-phase carbon nitride @ nickel-based layered double metal hydroxide composite membrane according to claim 1, wherein in the step (1), the dialysis layer used for dialysis has a permeation molecular weight of 1000 to 5000 Da, the dialysis time is 3 to 5 days, and preferably, the solid phase base is one or more of sodium hydroxide or potassium hydroxide.
  3. 3. The preparation method of the graphite-phase carbon nitride@nickel-based layered double metal hydroxide composite film according to claim 1 is characterized by comprising the following steps of (1) preparing graphite-phase carbon nitride by a supermolecular self-assembly method, namely dissolving melamine and phosphoric acid in deionized water according to a mass ratio of 1:1-2, performing hydrothermal reaction at 120-180 ℃ for 6-10 h, performing hydrothermal reaction to obtain a layered precursor, and then performing intercalation treatment and heat treatment under inert atmosphere to obtain the graphite-phase carbon nitride nano-sheet; The intercalation treatment comprises the steps of centrifugally washing a layered precursor by deionized water, drying at 60-80 ℃, dispersing the precursor in a mixed solution of ethanol and glycerol in a volume ratio of 3:1 for further stripping the layered structure, refluxing at 80-100 ℃ for 1-3 h for intercalation treatment, repeatedly washing by ethanol, and drying at 60 ℃ to obtain an intercalation modified layered precursor; the heat treatment under the inert atmosphere is that the intercalation precursor is placed in the inert atmosphere, the temperature is raised to 500-600 ℃, and the temperature is kept at 3-4 h ℃ to prepare the graphite phase carbon nitride nano-sheet.
  4. 4. The method for producing a graphite-phase carbon nitride @ nickel-based layered double metal hydroxide composite film according to claim 1, wherein in the step (2), the soluble nickel salt is one or more of nickel nitrate, nickel chloride or nickel acetate, and preferably, the stirring time is 12 to 24 hours.
  5. 5. The method for preparing a graphite phase carbon nitride @ nickel-based layered double metal hydroxide composite membrane according to claim 1, wherein in step (3), the precipitant is one or more of ethanolamine, urea or hexamethylenetetramine, and preferably, the time of standing is 12 to 48 hours.
  6. 6. The method of producing a graphite-phase carbon nitride @ nickel-based layered double metal hydroxide composite film according to claim 1, wherein in step (3), a dry weight mass ratio of the hydroxylated graphite-phase carbon nitride nanoplatelets to the precursor of the nickel-based layered double metal hydroxide is (2.0-4.0): 1, preferably the mass ratio is (2.0-3.0): 1, more preferably the mass ratio is 2.75:1.
  7. 7. The method for preparing a graphite phase carbon nitride @ nickel-based layered double metal hydroxide composite membrane according to claim 1, wherein in the step (4), the deposition mode is a positive pressure filtration method for forming a membrane, and the pressure is 0.05-0.2 MPa.
  8. 8. The method for producing a graphite phase carbon nitride @ nickel-based layered double metal hydroxide composite film according to claim 1, wherein in the step (4), the porous substrate is anodized aluminum.
  9. 9. A graphite-phase carbon nitride @ nickel-based layered double metal hydroxide composite film produced by the production method of the graphite-phase carbon nitride @ nickel-based layered double metal hydroxide composite film of any one of claims 1 to 8, which has a film thickness of 400 to 600nm.
  10. 10. The use of a graphite-phase carbon nitride @ nickel-based layered double hydroxide composite membrane according to claim 9 in gas separation, characterized by being used in the separation of a hydrogen and carbon dioxide mixture.

Description

Graphite-phase carbon nitride@nickel-based layered double metal hydroxide composite film and preparation method and application thereof Technical Field The invention belongs to the field of membrane separation, and particularly relates to a preparation method of a graphite phase carbon nitride@nickel-based layered double metal hydroxide composite membrane and application of the composite membrane in gas separation. Background Along with the transformation of the global energy structure to clean low carbon, the hydrogen energy is used as a high-efficiency and zero-carbon secondary energy carrier and has an irreplaceable effect in the fields of chemical synthesis, petroleum refining, fuel cells, electronic industry and the like. However, crude hydrogen obtained from industrial byproduct hydrogen or fossil fuel hydrogen production often contains impurities such as carbon dioxide, nitrogen, methane and the like, and needs to be purified with high efficiency to meet the severe requirements of downstream application on the purity of the hydrogen (generally, the requirement is more than 99.9%). Although the traditional cryogenic separation, pressure swing adsorption and other technologies are mature, the technology has the limitations of high energy consumption, complex process flow, large equipment investment and the like. In contrast, the membrane separation technology provides a very promising solution for the low-carbon and high-efficiency purification of hydrogen by virtue of the unique advantages of low energy consumption, simple and convenient operation and easy integration and amplification. Development of a separation membrane with high hydrogen permeation flux and high selectivity is a core for promoting the practical application of the technology. The prior art CN120679372A discloses a high-stability hydrated covalent organic framework membrane which comprises an ionic covalent organic framework and a self-supporting flexible substrate, and is prepared by a vacuum-assisted self-assembly method, wherein the membrane thickness is smaller than 100nm, the membrane aperture is 2+/-0.2 nm, and the covalent organic framework is a nano-sheet polymerized by an aldehyde monomer 1,3, 5-trimethylphloroglucinol and an amino monomer 4,4 '-diamino-3.3' -biphenyl disulfonic acid by a phase transfer method, and can be used for purifying natural gas. Graphite-phase carbon nitride is a potential film-forming material, but the film is made of the graphite-phase carbon nitride, so that an internal channel is narrow, and the gas flowing speed is low. Although its performance can be improved by chemical treatment (hydroxylation), the boosting effect is limited. Another material, nickel-based layered double hydroxide, has a unique layered structure. However, if the two are simply and physically mixed, it is difficult to realize uniform recombination and strong interface combination on the nano scale, thereby restricting further improvement of separation performance. The research proposes an in-situ growth strategy, namely, by directly introducing a nickel source and a precipitant into a hydroxylated graphite phase carbon nitride dispersion system, the layered double hydroxide grows in situ on the surface of the layered double hydroxide so as to obtain a more uniform composite structure and stronger interface interaction than a physical mixing method. Disclosure of Invention In order to solve the defects and shortcomings of the prior art, the invention aims to provide a composite membrane with strong interface bonding, excellent and stable gas separation performance and a simple and controllable preparation method thereof, which are used for hydrogen purification. In a first aspect, the invention provides a preparation method of a graphite-phase carbon nitride @ nickel-based layered double metal hydroxide composite membrane, which comprises the following steps: (1) Providing an aqueous dispersion of hydroxylated graphite phase carbon nitride nanoplatelets; specifically, mixing the solid-phase graphite-phase carbon nitride nanosheets with solid-phase alkali, performing ball milling, adding deionized water after ball milling, performing ball milling again, dialyzing, centrifuging, and standing to obtain the hydroxylated graphite-phase carbon nitride nanosheets aqueous solution. Preferably, the rotational speed of the ball mill is 300-1000 r/min, preferably 300-500 r/min. (2) Adding a precipitator into the mixed solution obtained in the step (2), reacting for 0.5-2 hours at 15-25 ℃, and inducing nickel-based layered double metal hydroxide to nucleate and grow on the surface of the hydroxylated graphite phase carbon nitride nano sheet in situ to obtain hydroxylated graphite phase carbon nitride@nickel-based layered double metal hydroxide composite nano sheet dispersion; (4) And (3) depositing the composite nano sheet dispersion liquid obtained in the step (3) on a porous substrate, and drying to obtain the composite film. Preferabl