CN-121988178-A - Trapezoid polysilsesquioxane gas separation membrane and preparation method and application thereof

Abstract

The invention discloses a trapezoid polysilsesquioxane gas separation membrane, a preparation method and application thereof, and solves the technical problems that the existing polymer membrane is easy to plasticize under a high-pressure working condition, so that the separation selectivity of CO 2 /CH 4 is reduced, and the performance is attenuated. According to the invention, the chemical structure of the trapezoid polysilsesquioxane is regulated, and the crosslinking agents with different steric hindrance are adopted to perform controllable crosslinking reaction with the trapezoid polysilsesquioxane, so that a stable three-dimensional covalent network is constructed among polymer chains. The method further inhibits chain segment migration from molecular scale, and obviously enhances the intrinsic plasticizing resistance and the integral separation efficiency of the material while maintaining the film forming capability of the material.

Inventors

• WANG BO
• YU LIANG
• FENG XIAO
• WANG JIAHUI

Assignees

• 北京理工大学

Dates

Publication Date

20260508

Application Date

20260331

Claims (8)

1. 1. The preparation method of the trapezoid polysilsesquioxane gas separation membrane is characterized by comprising the following steps of: s1, preparing ladder-shaped polysilsesquioxane Mixing potassium carbonate, deionized water and tetrahydrofuran by adopting an alkali catalytic sol-gel method, uniformly stirring, sequentially adding phenyl trimethoxy silane and 3-glycidoxypropyl trimethoxy silane into a mixed system, and continuously stirring and reacting for 5 days at 25 ℃, wherein after the reaction is finished, washing, extracting, filtering and drying the product sequentially to obtain ladder-shaped polysilsesquioxane powder; s2, preparing casting film liquid Respectively preparing a ladder-shaped polysilsesquioxane solution and an amine cross-linking agent solution, uniformly mixing the two solutions according to a set proportion to obtain a casting solution, carrying out ultrasonic treatment on the casting solution for 20min, and removing bubbles; S3, preparing a primary membrane Pouring the defoamed casting film liquid into a polytetrafluoroethylene forming die, and drying for 12-24 hours at room temperature to obtain a primary film; S4, thermal crosslinking and curing Drying the nascent membrane, removing residual solvent, completing ring-opening crosslinking reaction of epoxy groups and amino groups, and constructing a three-dimensional covalent network among polymer chains to prepare the chemically crosslinked modified trapezoid polysilsesquioxane gas separation membrane.
2. 2. The method for preparing a trapezoid polysilsesquioxane gas separation membrane according to claim 1, wherein in the step S1, the molar ratio of phenyl trimethoxysilane to 3-glycidoxypropyl trimethoxysilane is (1-9): (9~1).
3. 3. The method for producing a ladder polysilsesquioxane gas separation membrane according to claim 1, wherein in step S2, the amine-based crosslinking agent is at least one of a diamine-based crosslinking agent, a triamine-based crosslinking agent, and a tetramine-based crosslinking agent.
4. 4. The method for producing a trapezoid polysilsesquioxane gas separation membrane according to claim 3, wherein the mass fraction of the crosslinking agent is 0.25wt% to 1wt%.
5. 5. The method for preparing a trapezoid polysilsesquioxane gas separation membrane according to claim 1, wherein in the step S4, the drying temperature is 150-200 ℃ and the drying time is 4-6 hours.
6. 6. A trapezoidal polysilsesquioxane gas separation membrane produced by the method of producing a trapezoidal polysilsesquioxane gas separation membrane according to any one of claims 1 to 5.
7. 7. Use of a trapezoidal polysilsesquioxane gas separation membrane according to claim 6 in decarbonization of high pressure natural gas.
8. 8. The use of a trapezoidal polysilsesquioxane gas separation membrane according to claim 7, wherein the operating pressure for decarbonization of high pressure natural gas is 0.2mpa to 3mpa and the operating temperature is room temperature.

Description

Trapezoid polysilsesquioxane gas separation membrane and preparation method and application thereof Technical Field The invention relates to the technical field of gas separation membranes, in particular to a trapezoid polysilsesquioxane gas separation membrane, and a preparation method and application thereof. Background In the transition from traditional fossil energy to renewable energy, natural gas plays an indispensable transitional bridge role by virtue of its abundant reserves, higher energy density and relatively clean combustion characteristics. However, the feed gas produced from gas wells typically contains significant concentrations of carbon dioxide (up to 2% -30%), and such acid gas impurities can corrode the transfer piping equipment and reduce the combustion heating value, thus requiring efficient removal prior to entry into the pipeline. The existing common natural gas decarbonization technology is an absorption method and a pressure swing adsorption method, the development of the prior art is relatively mature, but the existing natural gas decarbonization technology also has problems such as high cost, high energy consumption and low operation flexibility. In contrast, membrane-based separation technologies are considered as representative of new generation decarbonization technologies because of their advantages of modularity, low energy consumption, and ease of operation. The natural gas at the wellhead is directly treated under high pressure by adopting a membrane separation technology, so that the gas treatment flux per unit membrane area can be obviously improved, and the energy consumption and cost of subsequent recompression can be avoided or reduced. Currently, commercial polymer membranes (e.g., cellulose acetate membranes, polyimide membranes, etc.) have been used for low pressure natural gas decarbonization. However, in the high pressure environment of a real natural gas well, such polymer membranes are extremely susceptible to plasticization, causing structural changes in the membrane materials, resulting in a decrease in the separation selectivity of CO 2/CH4, an abnormal increase in the permeation flux of CO 2, and an irreversible decay in the membrane performance. The plasticizing problem not only seriously affects the long-term operation stability and the service life of the separation system, but also becomes a key obstacle for restricting the popularization of the membrane separation technology to large-scale industrial application. Aiming at the technical bottleneck, the invention selects the trapezoid polysilsesquioxane as a film material. At present, the disclosed trapezoidal polymer related invention mainly focuses on a synthesis method and application thereof in the fields of batteries, catalysis, photoelectricity and the like, and research related to gas separation is also limited to low-pressure conditions. In contrast, the invention aims to develop a natural gas separation membrane material which is applicable to high-pressure environment and has excellent decarburization performance. Through designing and preparing the cross-linked trapezoid polysilsesquioxane gas separation membrane, the gas permeation performance and the plasticizing resistance of the cross-linked trapezoid polysilsesquioxane gas separation membrane under high pressure are systematically researched, so that the practical application of the material in high-pressure natural gas decarburization is promoted. Disclosure of Invention The invention aims to provide a trapezoid polysilsesquioxane gas separation membrane, and a preparation method and application thereof, so as to solve the technical problems of CO 2/CH4 separation selectivity reduction and performance attenuation caused by plasticization easily occurring under a high-pressure working condition of the existing polymer membrane. In order to achieve the above purpose, the present invention provides the following technical solutions: In a first aspect, the present invention provides a method for preparing a trapezoidal polysilsesquioxane gas separation membrane, comprising the steps of: s1, preparing ladder-shaped polysilsesquioxane Mixing potassium carbonate, deionized water and tetrahydrofuran by adopting an alkali catalytic sol-gel method, uniformly stirring, sequentially adding phenyl trimethoxy silane and 3-glycidoxypropyl trimethoxy silane into a mixed system, and continuously stirring and reacting for 5 days at 25 ℃, wherein after the reaction is finished, washing, extracting, filtering and drying the product sequentially to obtain ladder-shaped polysilsesquioxane powder; s2, preparing casting film liquid Respectively preparing a ladder-shaped polysilsesquioxane solution and an amine cross-linking agent solution, uniformly mixing the two solutions according to a set proportion to obtain a casting solution, carrying out ultrasonic treatment on the casting solution for 20min, and removing bubbles; S3, preparing a primary membrane Pouri