Polyphenyl modified composite silicon film and preparation method and application thereof
By preparing a polyphenyl-modified composite silicon membrane, the problem of insufficient CO2/N2 separation performance of existing organosilicon membranes was solved, and the overall improvement of CO2 selectivity and flux was achieved, making it suitable for the field of gas separation.
Patent Information
- Application Number
- CN202511608952.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-05
- Publication Date
- 2026-01-27
AI Technical Summary
The performance of existing organosilicon membranes in the field of CO2/N2 separation still needs to be optimized. The key issue is how to improve their permeation selectivity and hydrothermal stability through molecular structure design or surface modification.
A composite silicon membrane modified with polyphenylene was prepared by copolymerization reaction of a mixture of 1,4-bis(triethoxysilyl)benzene and 2-(4'-biphenylmethyl)-1,4-bis(triethoxysilyl)benzene as a separation layer, and a porous α-alumina ceramic tube was used as a support to form the composite silicon membrane at high temperature through a sol-gel process.
A balance between CO2 selectivity and flux was achieved during CO2/N2 separation. By forming a highly cross-linked dense structure and π-π electron interactions, the separation performance of the membrane was significantly improved.
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Figure CN121401889A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of membrane material preparation technology, specifically relating to a polyphenyl-modified composite silicon membrane, its preparation method, and its application. Background Technology
[0002] Studies have shown that accumulated CO2 and other greenhouse gases in the atmosphere are the main drivers of the greenhouse effect. CO2 radiation accounts for up to 50% of this effect. Therefore, developing efficient carbon capture and storage technologies is crucial for achieving carbon neutrality. Among numerous separation technologies, membrane separation has become a research hotspot due to its advantages such as low energy consumption and modular design. Organosilicon-based separation membranes, with their excellent hydrothermal stability and permeation selectivity, have shown significant potential for industrial application.
[0003] Although organosilicon membranes prepared by methods such as sol-gel and chemical vapor deposition have made progress in the field of CO2 / N2 separation, their performance still needs to be optimized. Therefore, how to improve performance through molecular structure design or surface modification remains a key scientific problem that urgently needs to be solved in this field. Summary of the Invention
[0004] In view of the technical problems existing in the prior art, the present invention provides a polyphenyl-modified composite silicon film, which is composed of a support and a separation layer.
[0005] Further, the separation layer is a 1,4-bis(triethoxysilyl)benzene BTESB / 2-(4'-biphenylmethyl)-1,4-bis(triethoxysilyl)benzene BTESBph-CH2 membrane; the BTESB / BTESBph-CH2 membrane is prepared by copolymerization of BTESB and BTESBph-CH2.
[0006] Furthermore, the molar ratio of BTESB to BTESBph-CH2 is 9.5:0.5-7:3.
[0007] Furthermore, the support is a porous α-alumina ceramic tube.
[0008] Furthermore, the BTESBph-CH2 is prepared by reacting BTESB with 4-bromomethylbiphenyl, and the reaction formula for preparing BTESBph-CH2 is shown below: .
[0009] This invention also provides a method for preparing a polyphenyl-modified composite silicon film, comprising the following steps: (1) Mix the reaction solvent and BTESB, then add BTESBph-CH2, using acid as a catalyst, and react under constant temperature and continuous stirring conditions to obtain composite silica sol. The reaction solvent is ethanol; the acid catalyst is either hydrochloric acid or nitric acid.
[0010] The mass fraction of BTESB in the composite silica sol is 1-5 wt%; the molar ratio of BTESB, deionized water, and acid is 1:240:0.2.
[0011] The constant temperature and continuous stirring temperature is 50℃, and the stirring time is 1~4h.
[0012] (2) Using a porous α-alumina ceramic tube as a support, a composite silica sol is coated as a separation layer and calcined at high temperature to form a film, thereby obtaining a polyphenyl-modified composite silica film.
[0013] The high-temperature calcination temperature is 300-500℃, the time is 30min, and the calcination atmosphere is N2.
[0014] Another object of the present invention is to provide an application of a polyphenyl-modified composite silicon membrane in gas separation, wherein the gas separation system is CO2 / N2 and the separation temperature is 25~200℃.
[0015] The beneficial effects of this invention are: This invention prepares a film from 1,4-bis(trimethoxysilyl)benzene (BTESB) and 2-(4'-biphenylmethyl)-1,4-bis(triethoxysilyl)benzene (BTESBPh-CH2) with rigid benzene ring structures via a sol-gel copolymerization process. The obtained composite silicon film exhibits a unique microstructure and excellent separation performance, mainly attributed to the following two synergistic mechanisms: First, the introduction of BTESBh-CH2 forms a highly cross-linked, dense structure, generating a molecular sieving effect that effectively inhibits the permeation of gas molecules; second, the π-π electronic interaction between the aromatic ring and CO2 molecules selectively promotes CO2 adsorption and transport. Attached Figure Description
[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0017] in: Figure 1 Schematic diagram of the film-forming and permeability mechanism of BTESB sol (left) and BTESB / BTESBph-CH2 sol (right).
[0018] Figure 2The particle size analysis (DLS) diagrams are for the membranes prepared in Comparative Example 1, Comparative Example 2, and Examples 1-4.
[0019] Figure 3 Fourier transform infrared (FT-IR) images of the films prepared in Comparative Example 1, Comparative Example 2, and Examples 1-4.
[0020] Figure 4 The image shown is a scanning electron microscope (SEM) image of the membrane prepared in Example 3.
[0021] Figure 5 X-ray diffraction (XRD) patterns of the films prepared in Comparative Example 1, Comparative Example 2, and Examples 1-4. Detailed Implementation
[0022] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the examples in the specification.
[0023] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and those skilled in the art can make similar extensions without departing from the spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed below.
[0024] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it a single or selective embodiment that is mutually exclusive with other embodiments.
[0025] Unless otherwise specified, all raw materials used in this invention are commercially available in the field.
[0026] The abbreviations for the organosilicon precursors used in this invention are as follows: 1,4-bis(triethoxysilyl)benzene (BTESB), 2-(4'-biphenylmethyl)-1,4-bis(triethoxysilyl)benzene (BTESBph-CH2), 1,2-bis(triethoxysilyl)ethane (BTESE).
[0027] The support used in this invention is tubular alumina with a pore size of 1µm and a porosity of 50%.
[0028] The present invention uses a polyphenyl-modified composite silicon membrane for CO2 / N2 separation, and the following method is used: place the membrane tube in the membrane module, connect it to the gas cylinder, control the inlet pressure to 100 kPa, and measure the membrane flux for CO2 and N2 and the CO2 / N2 selectivity at different temperatures.
[0029] Example 1
[0030] Preparation of BTESBph-CH2: 10 mmol of BTESB was added to 50 mL of dry anhydrous dichloromethane (DCM), followed by 10 mmol of 4-bromomethylbiphenyl and 0.15 mmol of anhydrous FeCl3 at room temperature. The reaction was then carried out at room temperature under N2 conditions for 12 h. The reaction solution was quenched with deionized water, then extracted, dried, and filtered. The resulting organic phase was used to evaporate the DCM using a rotary evaporator. Finally, the mixture was separated and purified to obtain the desired BTESBph-CH2.
[0031] (1) Preparation of BTESB / BTESBph-CH2=9.5:0.5 (molar ratio) sol
[0032] 1 g of BTESB was added to 38.17 g of ethanol, and then a solution of 0.07 g of BTESBph-CH2 and 10.73 g of deionized water was added to the above solution. Finally, 0.03 g of nitric acid was added as a catalyst, and the mixture was stirred at 50 °C for 2 h to obtain BTESB / BTESBph-CH2 sol.
[0033] (2) Membrane preparation
[0034] The BTESB / BTESBph-CH2=9.5:0.5 sol was diluted with anhydrous ethanol to a total content of organosilicon monomers (the total content of BTESB+BTESBph-CH2 as a percentage of the total solution mass) of 0.5 wt%. The sol was then coated onto a support (film thickness approximately 500 nm) using a cotton swab. The support was then calcined in a tube furnace at 300 °C under a nitrogen atmosphere for 30 min. This process was repeated twice to obtain the BTESB / BTESBph-CH2 film, which was designated as BTESB / BTESBph-CH2(9.5:0.5).
[0035] Example 2
[0036] (1) Preparation of BTESB / BTESBph-CH2=9:1 sol
[0037] 1 g of BTESB was added to 38.08 g of ethanol, and then a solution of 0.16 g of BTESBph-CH2 and 10.73 g of deionized water was added to the above solution. Finally, 0.03 g of nitric acid was added as a catalyst, and the mixture was stirred at 50 °C for 2 h to obtain BTESB / BTESBph-CH2 sol.
[0038] (2) Preparation of membrane, same as in Example 1, the membrane is denoted as BTESB / BTESBph-CH2(9:1).
[0039] Example 3
[0040] (1) Preparation of BTESB / BTESBph-CH2=8:2 sol
[0041] 1 g of BTESB was added to 37.89 g of ethanol, and then a solution of 0.35 g of BTESBph-CH2 and 10.73 g of deionized water was added to the above solution. Finally, 0.03 g of nitric acid was added as a catalyst, and the mixture was stirred at 50 °C for 2 h to obtain BTESB / BTESBph-CH2 sol.
[0042] (2) Preparation of membrane, same as in Example 1, the membrane is denoted as BTESB / BTESBph-CH2(8:2).
[0043] Example 4
[0044] (1) Preparation of BTESB / BTESBph-CH2=7:3 sol
[0045] 1 g of BTESB was added to 37.63 g of ethanol, and then a solution of 0.61 g of BTESBph-CH2 and 10.73 g of deionized water was added to the above solution. Finally, 0.03 g of nitric acid was added as a catalyst, and the mixture was stirred at 50 °C for 2 h to obtain BTESB / BTESBph-CH2 sol.
[0046] (2) Preparation of membrane, same as in Example 1, the membrane is denoted as BTESB / BTESBph-CH2(7:3).
[0047] Example 5
[0048] (1) Preparation of sol is the same as in Example 3.
[0049] (2) The membrane preparation is the same as in Example 1, except that the calcination temperature of the membrane is changed to 400℃, which is denoted as BTESB / BTESBph-CH2(8:2) (400℃).
[0050] Example 6
[0051] (1) The preparation of the sol is the same as in Example 3, except that 0.03g of nitric acid is replaced with 0.03g of acetic acid.
[0052] (2) Preparation of the membrane, same as in Example 1, the membrane is denoted as BTESB / BTESBph-CH2 (8:2) (acetic acid).
[0053] Comparative Example 1
[0054] (1) Preparation of BTESB sol
[0055] 1 g of BTESB was added to 48.24 g of ethanol, then 10.73 g of deionized water was added to the above solution, and finally 0.03 g of nitric acid was added as a catalyst. The mixture was stirred at 50 °C for 2 h to obtain BTESB sol.
[0056] (2) Preparation of the membrane: Same as in Example 1, the membrane is referred to as BTESB.
[0057] Comparative Example 2
[0058] (1) Preparation of BTESBph-CH2 sol
[0059] 1 g of BTESBph-CH2 was added to 41.39 g of ethanol, then 7.59 g of deionized water was added to the above solution, and finally 0.02 g of nitric acid was added as a catalyst. The mixture was stirred at 50 °C for 2 h to obtain BTESBph-CH2 sol.
[0060] (2) Preparation of the membrane: Same as in Example 1, the membrane is denoted as BTESBph-CH2.
[0061] Comparative Example 3
[0062] (1) Preparation of BTESE / BTESE=8:2 sol
[0063] 1 g of BTESB was added to 38.02 g of ethanol, and then a solution of 0.22 g of BTESE and 10.73 g of deionized water was added to the above solution. Finally, 0.03 g of nitric acid was added as a catalyst, and the mixture was stirred at 50 °C for 2 h to obtain BTESB / BTESE sol.
[0064] (2) The membrane was prepared in the same manner as in Example 1. The membrane was denoted as BTESEB / BTESE(8:2).
[0065] The organosilicon membranes prepared in Examples 1-6 and Comparative Examples 1-3 were applied to CO2 / N2 separation. The membrane tube was placed in the membrane module and connected to a gas cylinder. The inlet pressure was controlled at 100 kPa, and the test temperature was 25~200 °C. The test results are shown in Table 1.
[0066] Table 1. CO2 and N2 fluxes and CO2 / N2 selectivity of different membranes at 25 °C
[0067] Table 2. CO2 and N2 fluxes and CO2 / N2 selectivity of different membranes at 200 °C
[0068] Table 3. CO2 and N2 fluxes and CO2 / N2 selectivity of different membranes at 100 °C
[0069] As shown in Table 1, compared to pure BTESB membranes, the flux of composite silicon membranes decreases, but their selectivity for CO2 / N2 is relatively improved. This is because ( Figure 1 The network structure formed by the composite silicon membrane is smaller than that of the BTESB membrane, and the addition of BTESBph-CH2 effectively hinders the passage of N2. Furthermore, due to the presence of biphenyl within the pore structure, it forms a π-π complex with CO2, thus compensating for the loss of CO2 flux due to the reduced pore size. By controlling the amount of BTESBph-CH2 added, the membrane material achieves the best overall selectivity and flux for CO2.
[0070] In summary, when the molar ratio of BTESB / BTESBph-CH2 is 8:2, the sol-gel reaction conditions are 50℃ for 2 hours, and the calcination temperature of the membrane is 300℃, the combined gas permeability and selectivity of the membrane are optimal, and the selectivity of the CO2 / N2 separation system of the membrane material is improved compared with that of the pure membrane.
[0071] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.
Claims
1. A polyphenyl-modified composite silicon film, characterized in that, The composite silicon membrane consists of a support and a separation layer; the separation layer is a 1,4-bis(triethoxysilyl)benzene BTESB / 2-(4'-biphenylmethyl)-1,4-bis(triethoxysilyl)benzene BTESBph-CH2 membrane, which is prepared by copolymerization of BTESB and BTESBph-CH2.
2. The polyphenyl-modified composite silicon film as described in claim 1, characterized in that, The molar ratio of BTESB to BTESBph-CH2 in the BTESB / BTESBph-CH2 membrane is 9.5:0.5-7:
3.
3. The polyphenyl-modified composite silicon film as described in claim 1, characterized in that, The support is a porous α-alumina ceramic tube.
4. The polyphenyl-modified composite silicon film as described in claim 1, characterized in that, The BTESBph-CH2 is prepared by reacting BTESB with 4-bromomethylbiphenyl. The reaction formula for preparing BTESBph-CH2 is shown below: 。 5. A method for preparing a polyphenyl-modified composite silicon film as described in claim 1, characterized in that, The preparation method steps are as follows: (1) Mix the reaction solvent and BTESB, then add BTESBph-CH2 and acid catalyst, and react under constant temperature and continuous stirring conditions to obtain composite silica sol; (2) The composite silica sol is coated on the support and calcined at high temperature to form a separation layer, thereby obtaining a polyphenyl-modified composite silica film.
6. The method for preparing the polyphenyl-modified composite silicon film as described in claim 5, characterized in that, In step (1), the reaction solvent is ethanol; the acid catalyst is hydrochloric acid or nitric acid; the constant temperature and continuous stirring temperature is 50℃, and the stirring time is 1-4h.
7. The method for preparing the polyphenyl-modified composite silicon film as described in claim 5, characterized in that, In step (1), the mass fraction of BTESB in the composite silica sol is 1-5 wt%; the molar ratio of BTESB, deionized water, and acid is 1:240:0.
2.
8. The method for preparing the polyphenyl-modified composite silicon film as described in claim 5, characterized in that, In step (2), the high-temperature calcination temperature is 300-500℃, the time is 30min, and the calcination atmosphere is N2.
9. An application of the polyphenyl-modified composite silicon film as described in claim 1, characterized in that: The polyphenyl-modified composite silicon membrane is used for gas separation.
10. The application of the polyphenyl-modified composite silicon film as described in claim 9, characterized in that, The gas separation system is CO2 / N2, and the separation temperature is 25~200℃.