A method for preparing all-silicon molecular sieve glass fiber composite material

Abstract

The present invention relates to the technical field of glass fiber composite materials, and in particular to a method for preparing a full-silicon molecular sieve glass fiber composite material, comprising: mixing silicate and an organic structure directing agent and continuously stirring for a period of time to perform hydrolysis and alcohol evaporation; then transferring the mixture to an autoclave and maintaining it at a certain temperature for a period of time, collecting the solid product, and heating it to a certain temperature at a certain heating rate and calcining it in the air for several hours; then dispersing the obtained powder into a silica gel solution with a certain solid content to form a mixed suspension; finally spraying the mixed suspension onto glass fiber paper with a high-pressure spray gun, thereby forming a full-silicon molecular sieve glass fiber material. The present invention realizes the full silicification of molecular sieves, and the obtained full-silicon molecular sieve glass fiber material solves the industry problems of poor hydrophobicity of traditional molecular sieve adsorption materials and pore plugging during adsorption and desorption of easily polymerized VOCs, and has good application prospects and economic benefits in the field of industrial VOCs flue gas purification.

Description

Technical Field

[0001] The invention relates to the technical field of glass fiber composite materials, and in particular to a method for preparing an all-silicon molecular sieve glass fiber composite material. Background Art

[0002] VOCs are directive organic compounds, a class of organic substances with high volatility, flammability and toxicity, which are widely present in industrial production and life. VOCs cause serious harm to the environment and human health, so they need to be effectively controlled and treated. At present, the main methods for purifying industrial VOCs are adsorption, catalytic combustion, biological methods, etc. Among them, adsorption is a commonly used low-concentration VOCs purification method. Its principle is to use the physical or chemical action on the surface of the adsorbent to transfer VOCs from the gas phase to the solid phase to achieve purification. It uses adsorbents to selectively adsorb organic matter in VOCs waste gas, and then desorbs the organic matter on the adsorbent through a regeneration method, thereby achieving the purification and resource utilization of VOCs waste gas.

[0003] In order to improve the performance and economy of the adsorption method, it is necessary to develop new adsorbent materials. Molecular sieve is a crystalline material with a regular pore structure that can selectively adsorb different substances according to the size and shape of the molecule. Molecular sieve has the characteristics of large specific surface area, high pore capacity, and strong selectivity, and is an ideal adsorbent material. However, traditional molecular sieve adsorbents also have some problems, mainly: (1) Molecular sieves themselves are hydrophilic and easily absorb water, resulting in decreased adsorption capacity and high energy consumption for VOCs desorption; (2) Molecular sieves are prone to polymerization reactions during the adsorption and desorption of easily polymerized substances such as styrene, resulting in pore blockage, structural damage, and decreased activity; (3) Molecular sieve powder is difficult to directly apply to industrial equipment and needs to be composited with other carriers or binders. However, traditional composite processes often use various surfactants, diluents and other additives, which increases cost and complexity. These problems limit the application of molecular sieves in treating high-humidity and easily polymerized VOCs waste gas from industrial sources.

[0004] Therefore, in order to solve the above technical problems, it is necessary for the present application to provide a method for preparing an all-silicon molecular sieve glass fiber composite material to improve the adsorption and desorption purification efficiency and stability of VOCs waste gas. Summary of the invention

[0005] The purpose of the present invention is to solve the shortcomings existing in the prior art and propose a method for preparing an all-silicon molecular sieve glass fiber composite material. The all-silicon molecular sieve glass fiber material prepared by the present invention solves the industry problems of poor hydrophobicity of traditional molecular sieve adsorption materials and pore blockage during adsorption and desorption of easily polymerized VOCs, and has good application prospects and economic benefits in the field of industrial VOCs flue gas purification.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A method for preparing an all-silicon molecular sieve glass fiber composite material, the specific steps are as follows:

[0008] S1, mixing silicate and organic structure directing agent in proportion, and stirring for a period of time to obtain a mixture;

[0009] S2, transferring the mixture in S1 into an autoclave, and maintaining it at a certain temperature for a period of time to obtain a solid product;

[0010] S3, heating the solid product in S2 to a certain temperature at a certain heating rate, and calcining it in air at a constant temperature for several hours to obtain a full silicon molecular sieve powder;

[0011] S4, dispersing the all-silicon molecular sieve powder obtained in S3 into a silica gel solution with a certain solid content to form a mixed suspension;

[0012] S5. Spray the mixed suspension in S4 onto the glass fiber paper using a high-pressure spray gun to form an all-silicon molecular sieve glass fiber composite material.

[0013] Preferably, in step S1, the silicate is a mixture of one or more of tetraethyl silicate, tetramethyl silicate, tetrapropyl silicate, tetraisopropyl silicate, tetrabutyl silicate and tetraphenyl silicate.

[0014] Preferably, in step S1, the organic structure directing agent is a mixture of one or more of tricyclohexylmethylphosphine, matrine, tetraethylammonium hydroxide, isopropylamine and tetramethylammonium hydroxide.

[0015] Preferably, in step S1, the molar ratio of silicate to organic structure directing agent is (1:1) to (5:1).

[0016] Preferably, in step S1, the mixture is stirred for 8 to 24 hours.

[0017] Preferably, in step S2, the autoclave reaction temperature is 150-200°C, and the reaction time is 480-960h.

[0018] Preferably, in step S3, the heating rate is 1-10°C / min, the constant temperature is 550-750°C, and the calcination time is 3-10h.

[0019] Preferably, in step S4, the solid content of the silica gel solution is 20% to 60%.

[0020] Preferably, in step S5, the high-pressure spray gun used has an air pressure of 0.4-0.6 Mpa and a flow rate of 30-180 L / h.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The preparation process of the present invention realizes full silicification of the molecular sieve, improves the hydrophobicity and stability of the molecular sieve, and enables it to maintain good adsorption performance under high humidity conditions.

[0023] 2. The present invention combines all-silicon molecular sieve with glass fiber paper, which increases the specific surface area, porosity and gas permeability of the material, and improves the adsorption capacity and adsorption rate of the material.

[0024] 3. The preparation method of the present invention is simple, controllable, low-cost, and suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a SEM image of the all-silicon molecular sieve prepared in Example 1 of the present invention;

[0026] Figure 2 This is a schematic diagram of the appearance of the sample prepared in Example 1 of the present invention after adsorption and desorption of styrene;

[0027] Figure 3 This is a schematic diagram of the appearance of the sample prepared in the control example of the present invention after adsorption and desorption of styrene. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings, so that those skilled in the art can better understand the advantages and features of the present invention, thereby making a clearer definition of the protection scope of the present invention. The embodiments described in the present invention are only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention.

[0029] Embodiment 1:

[0030] A method for preparing an all-silicon molecular sieve glass fiber composite material, the specific steps are as follows:

[0031] S1, using tetrapropyl silicate as silicate and tricyclohexyl methyl phosphine as organic structure directing agent, mixing them in a molar ratio of 2:1, and stirring for 12 hours;

[0032] S2, transferring the mixture into an autoclave and maintaining it at 180° C. for 600 h to obtain a solid product;

[0033] S3, heating the solid product to 650°C at a heating rate of 3°C / min, and calcining the solid product in air at a constant temperature for 5 hours to obtain an all-silicon molecular sieve powder;

[0034] S4, dispersing the all-silicon molecular sieve powder into a silica gel solution with a solid content of 40% to form a mixed suspension;

[0035] S5. Use a high-pressure spray gun to spray the mixed suspension onto the glass fiber paper at an air pressure of 0.5 MPa and a flow rate of 100 L / h, thereby forming an all-silicon molecular sieve glass fiber material.

[0036] from Figure 1 As can be seen from the SEM image in, the all-silicon molecular sieve prepared by this method has a linear structure with high openness and connectivity, which can effectively reduce the diffusion resistance and help improve the adsorption capacity, selectivity and stability of the molecular sieve.

[0037] The obtained all-silicon molecular sieve glass fiber material is 400mg / m 3 Styrene, gas adsorption and desorption surface velocity are 2m / s, atmosphere humidity is RH=100%, desorption temperature is 200℃, after 50 times of adsorption and desorption of styrene, the adsorption efficiency can still be maintained above 96%, and no obvious coking and carbon deposition is found on the surface of the adsorbent (such as Figure 2 shown).

[0038] Embodiment 2:

[0039] A method for preparing an all-silicon molecular sieve glass fiber composite material, the specific steps are as follows:

[0040] S1, using tetramethyl silicate and tetraethyl silicate mixed in a ratio of 1:1 as silicate, using matrine as an organic structure directing agent, mixing in a molar ratio of 3:1, and stirring for 10 hours;

[0041] S2, transferring the mixture into an autoclave and maintaining it at 160° C. for 720 h to obtain a solid product;

[0042] S3, heating the solid product to 600°C at a heating rate of 5°C / min, and calcining in air at a constant temperature for 6 hours to obtain an all-silicon molecular sieve powder;

[0043] S4, dispersing the all-silicon molecular sieve powder into a silica gel solution with a solid content of 30% to form a mixed suspension;

[0044] S5. Use a high-pressure spray gun to spray the mixed suspension onto the glass fiber paper at an air pressure of 0.4 MPa and a flow rate of 30 L / h, thereby forming an all-silicon molecular sieve glass fiber material.

[0045] The obtained all-silicon molecular sieve glass fiber material is 400mg / m 3For styrene, under the experimental conditions of gas adsorption surface velocity and desorption surface velocity both being 2m / s, atmosphere humidity being RH=100%, and desorption temperature being 200°C, after 50 times of adsorption and desorption of styrene, the adsorption efficiency can still be maintained above 90%, and no obvious coking or carbon deposition is found on the surface of the adsorbent.

[0046] Embodiment 3:

[0047] A method for preparing an all-silicon molecular sieve glass fiber composite material, the specific steps are as follows:

[0048] S1, using tetrabutyl silicate as silicate and tetraethylammonium hydroxide as organic structure directing agent, mixing them in a molar ratio of 4:1, and stirring for 16 hours;

[0049] S2, transferring the mixture into an autoclave and maintaining it at 200° C. for 960 h to obtain a solid product;

[0050] S3, heating the solid product to 750°C at a heating rate of 10°C / min, and calcining it in air at a constant temperature for 10 hours to obtain an all-silicon molecular sieve powder;

[0051] S4, dispersing the all-silicon molecular sieve powder into a silica gel solution with a solid content of 60% to form a mixed suspension;

[0052] S5. Use a high-pressure spray gun to spray the mixed suspension onto the glass fiber paper at an air pressure of 0.6 MPa and a flow rate of 30 L / h, thereby forming an all-silicon molecular sieve glass fiber material.

[0053] The obtained all-silicon molecular sieve glass fiber material is 400mg / m 3 For styrene, under the experimental conditions of gas adsorption surface velocity and desorption surface velocity both being 2m / s, atmosphere humidity being RH=100%, and desorption temperature being 200°C, after 50 times of adsorption and desorption of styrene, the adsorption efficiency can still be maintained above 92%, and no obvious coking or carbon deposition is found on the surface of the adsorbent.

[0054] Embodiment 4:

[0055] A method for preparing an all-silicon molecular sieve glass fiber composite material, the specific steps are as follows:

[0056] S1, using tetraisopropyl silicate as silicate and isopropylamine as organic structure directing agent, mixing them in a molar ratio of 1:1, and stirring for 8 hours;

[0057] S2, transferring the mixture into an autoclave and maintaining it at 150° C. for 480 h to obtain a solid product;

[0058] S3, heating the solid product to 550°C at a heating rate of 1°C / min, and calcining in air at a constant temperature for 3 hours to obtain an all-silicon molecular sieve powder;

[0059] S4, dispersing the all-silicon molecular sieve powder into a silica gel solution with a solid content of 20% to form a mixed suspension;

[0060] S5. Use a high-pressure spray gun to spray the mixed suspension onto the glass fiber paper at an air pressure of 0.4 MPa and a flow rate of 180 L / h, thereby forming an all-silicon molecular sieve glass fiber material.

[0061] The obtained all-silicon molecular sieve glass fiber material is 400mg / m 3 For styrene, under the experimental conditions of gas adsorption surface velocity and desorption surface velocity both being 2m / s, atmosphere humidity being RH=100%, and desorption temperature being 200°C, after 50 times of adsorption and desorption of styrene, the adsorption efficiency can still be maintained above 93%, and no obvious coking or carbon deposition is found on the surface of the adsorbent.

[0062] Embodiment 5:

[0063] A method for preparing an all-silicon molecular sieve glass fiber composite material, the specific steps are as follows:

[0064] S1, using tetraphenyl silicate as silicate and tetramethylammonium hydroxide as organic structure directing agent, mixing them in a molar ratio of 5:1, and stirring for 24 hours;

[0065] S2, transferring the mixture into an autoclave and maintaining it at 190° C. for 840 h to obtain a solid product;

[0066] S3, heating the solid product to 700°C at a heating rate of 8°C / min, and calcining in air at a constant temperature for 8 hours to obtain an all-silicon molecular sieve powder;

[0067] S4, dispersing the all-silicon molecular sieve powder into a silica gel solution with a solid content of 50% to form a mixed suspension;

[0068] S5. Use a high-pressure spray gun to spray the mixed suspension onto the glass fiber paper at an air pressure of 0.4 MPa and a flow rate of 120 L / h, thereby forming an all-silicon molecular sieve glass fiber material.

[0069] The obtained all-silicon molecular sieve glass fiber material is 400mg / m 3 For styrene, under the experimental conditions of gas adsorption surface velocity and desorption surface velocity both being 2m / s, atmosphere humidity being RH=100%, and desorption temperature being 200°C, after 50 times of adsorption and desorption of styrene, the adsorption efficiency can still be maintained above 91%, and no obvious coking or carbon deposition is found on the surface of the adsorbent.

[0070] Comparative Example 1:

[0071] S1, dispersing commercial ZSM-5 molecular sieve powder into a silica gel solution with a solid content of 40% to form a mixed suspension;

[0072] S2. Use a high-pressure spray gun to spray the mixed suspension onto glass fiber paper at an air pressure of 0.5 MPa and a flow rate of 100 L / h to form a ZSM-5 molecular sieve glass fiber material.

[0073] At 400 mg / m 3 Styrene, gas adsorption and desorption surface velocity are 2m / s, atmosphere humidity is RH=100%, desorption temperature is 200℃, under the adsorption and desorption purification experimental conditions, the surface of the obtained ZSM-5 molecular sieve glass fiber material has become brown after two times of adsorption and desorption of styrene, such as Figure 3 As shown, the adsorption efficiency is only 50%, and there is no adsorption effect after 50 times, indicating that the adsorbed styrene has undergone serious polymerization and pore blocking in its surface layer and pores.

[0074] The experimental results of the above Examples 1-5 and Comparative Example 1 are shown in Table 1:

[0075] Table 1 Comparison of the adsorption and desorption performance of styrene for all samples prepared

[0076]

[0077] In summary, the present invention synthesizes an all-silicon molecular sieve by using silicate and an organic structure directing agent according to a certain ratio and temperature, and efficiently loads it onto the surface of glass fiber through a high-pressure mist gun, thereby obtaining an all-silicon molecular sieve glass fiber adsorption material that is highly hydrophobic and resistant to VOCs polymerization and pore blocking, so that the all-silicon molecular sieve glass fiber adsorption material has good application prospects and economic benefits in the field of industrial VOCs flue gas purification.

[0078] The description and practice disclosed in the present invention are easy to think and understand for ordinary technicians in the technical field, and several improvements and modifications can be made without departing from the principles of the present invention. Therefore, modifications or improvements made without departing from the spirit of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing an all-silicon molecular sieve glass fiber composite material, It is characterized in that The specific steps are as follows: S1, using tetrapropyl silicate as silicate and tricyclohexylmethylphosphine as organic structure directing agent, mixing them in a molar ratio of 2:1, and stirring for 12 h; S2, transferring the mixture into an autoclave and maintaining it at 180 °C for 600 h to obtain a solid product; S3, heating the solid product to 650°C at a heating rate of 3°C / min, and calcining in air at a constant temperature for 5 h to obtain an all-silicon molecular sieve powder; S4, dispersing the all-silicon molecular sieve powder into a silica gel solution with a solid content of 40% to form a mixed suspension; S5. Use a high-pressure spray gun to spray the mixed suspension onto the glass fiber paper at an air pressure of 0.5 MPa and a flow rate of 100 L / h to form an all-silicon molecular sieve glass fiber material.

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