CN112675818A - Core-shell molecular sieve adsorbent for selectively adsorbing VOCs (volatile organic compounds) in high-humidity atmosphere and preparation method thereof - Google Patents

Core-shell molecular sieve adsorbent for selectively adsorbing VOCs (volatile organic compounds) in high-humidity atmosphere and preparation method thereof Download PDF

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CN112675818A
CN112675818A CN202011373777.4A CN202011373777A CN112675818A CN 112675818 A CN112675818 A CN 112675818A CN 202011373777 A CN202011373777 A CN 202011373777A CN 112675818 A CN112675818 A CN 112675818A
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molecular sieve
shell
core
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meso
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陆朝阳
张以飞
徐遵主
仪得志
张纪文
金小贤
刘�东
李明
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Nanjing University Environmental Planning And Design Institute Group Co Ltd
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Abstract

The invention provides a core-shell molecular sieve adsorbent for selectively adsorbing VOCs (volatile organic compounds) in a high humidity atmosphere and a preparation method thereof2Core-shell molecular sieve, depositing organosilane on the mesoporous silica shell to obtain organosilane-modified hydrophobic mesoporous silica shell, and finally obtaining hydrophobic Y @ meso-SiO2-S core shell adsorbent. The invention solves the problem of reduction or blockage of the orifice of the Y molecular sieve caused by grafting, depositing and modifying organosilane, and the shell phase Y molecular sieve keeps the original crystallinity, thereby showing higher adsorption capacity; the invention has reasonable design and convenient operation, and the prepared super-hydrophobic Y @ meso-SiO2the-S core-shell adsorbent can selectively adsorb VOCs in a high humidity atmosphere, is high in practicability and is suitable for popularization.

Description

Core-shell molecular sieve adsorbent for selectively adsorbing VOCs (volatile organic compounds) in high-humidity atmosphere and preparation method thereof
The technical field is as follows:
the invention belongs to the technical field of environmental protection, and particularly relates to a core-shell molecular sieve adsorbent for selectively adsorbing VOCs (volatile organic compounds) in a high-humidity atmosphere and a preparation method thereof.
Background art:
as the environment protection is more and more emphasized by the country, each enterprise effectively treats the VOCs and reduces the discharge of the VOCs. The adsorption method has the characteristics of high removal efficiency, thorough purification, low energy consumption, mature process, easy combination with other treatment methods and the like, and is very suitable for the treatment or recovery process of the low-concentration VOCs. Currently, the most used adsorbent in industry is activated carbon because of its advantages of many kinds of raw materials, wide sources, large specific surface area and abundant microporous structure. However, in practical application, industrial waste gas often has a large amount of water vapor, the adsorption performance of the activated carbon is easily affected by the water vapor, the activated carbon is not easy to regenerate, and particularly, a thermal regeneration treatment process after absorbing VOCs has fire hazard and does not meet the requirement of safe production.
The molecular sieve has the advantages of high temperature resistance, incombustibility, good regeneration performance, large adsorption capacity, wide application range and the like, so the molecular sieve is widely applied to the fields of gas separation, gas drying, wastewater treatment, oil product cleaning and the like. Among various molecular sieves, the Y-type zeolite molecular sieve has a three-dimensional twelve-membered ring channel structure, the average size of the channel reaches 0.74nm, most organic molecules can enter the channel to be adsorbed, and the Y-type molecular sieve has a large specific surface area and can adsorb more VOCs. However, the Y-type molecular sieve has lower silicon-aluminum ratio and can preferentially adsorb water molecules with higher polarity, and the strong hydrophilicity hinders further industrial application of the Y-type molecular sieve. The Y-type molecular sieve was found to adsorb few VOCs under high humidity conditions. Improvement for improving hydrophobicity of Y molecular sieve commonly used at presentThe method is characterized in that aluminum atoms in a molecular sieve framework are removed by adopting high-temperature steam treatment, so that the aim of improving the silicon-aluminum ratio of the molecular sieve is fulfilled. In order to obtain hydrophobic Y molecular Sieve (SiO) with higher silicon-aluminum ratio2/Al2O3>40) Many times of high-temperature hydrothermal treatment is often needed, but the multiple high-temperature hydrothermal treatment method has large damage to the crystallinity of the molecular sieve and large loss of specific surface area, thereby affecting the adsorption capacity of the molecular sieve. Researches show that the hydrophobic property of the outer surface of the molecular sieve crystal can be obviously improved by grafting and modifying the organosilane on the outer surface of the molecular sieve. However, the organic silane is loaded on the outer surface of the molecular sieve crystal, which causes the pore opening of the molecular sieve to be reduced or blocked, thereby leading to lower adsorption capacity. Based on the above, the invention provides a core-shell molecular sieve adsorbent for selectively adsorbing VOCs in a high humidity atmosphere and a preparation method thereof, so as to solve the above problems.
The invention content is as follows:
the invention aims to provide a core-shell molecular sieve adsorbent for selectively adsorbing VOCs (volatile organic compounds) in a high-humidity atmosphere, a preparation method and application thereof aiming at overcoming the defects of the prior art, and aims to solve the problem of reduction or blockage of a Y-shaped molecular sieve pore opening caused by grafting, depositing and modifying of organosilane.
The invention adopts the following technical scheme:
a preparation method of a core-shell molecular sieve adsorbent for selectively adsorbing VOCs in a high humidity atmosphere comprises the steps of firstly growing a mesoporous silica shell layer on the outer surface of a Y-type molecular sieve crystal to obtain Y @ meso-SiO2A core-shell molecular sieve; depositing organosilane on the mesoporous silica shell to obtain a hydrophobic mesoporous silica shell modified by the organosilane, and finally obtaining hydrophobic Y @ meso-SiO2-S core shell adsorbent.
Further, the invention specifically comprises the following steps:
s1, preparation of the modified Y-type molecular sieve:
mixing the Y-type molecular sieve with a poly (diallyldimethylammonium chloride) solution, stirring at room temperature, and then centrifugally washing and drying to obtain the poly (diallyldimethylammonium chloride) -modified Y-type molecular sieve;
S2、Y@meso-SiO2preparing a core-shell molecular sieve:
adding a certain amount of the modified Y-type molecular sieve prepared in S1 into a solution consisting of absolute ethyl alcohol, deionized water, ammonia water and hexadecyl trimethyl ammonium bromide, and performing ultrasonic dispersion to uniformly disperse the modified Y-type molecular sieve into the mixed solution; then weighing a certain mass of ethyl orthosilicate, dropwise adding the ethyl orthosilicate into the mixed solution, and continuously stirring; then, ethanol and water are adopted for full washing and filtration, and a filter cake is dried and roasted to obtain Y @ meso-SiO2A core-shell molecular sieve;
s3 hydrophobic Y @ meso-SiO2-preparation of S core shell adsorbent:
taking a certain amount of Y @ meso-SiO prepared in S22The core-shell molecular sieve is laid on the surface of the glass sheet, suspended in the air and placed in a closed glass container containing organosilane, and then the glass container is placed in an oven to be heated; after cooling, the super-hydrophobic Y @ meso-SiO is obtained2-S core shell adsorbent.
Further, in S1, the solid-liquid weight ratio of the Y-type molecular sieve to the poly (diallyldimethylammonium chloride) solution is 1 (20-80), preferably 1 (40-60); wherein the concentration of the poly (diallyldimethylammonium chloride) solution is 0.5-2.0 g/L, preferably 1.0-2.0 g/L.
Further, in S1, stirring for 1-6 h, centrifugally washing, and drying at 60-120 ℃ for 2-10 h.
Further, in S2, in the solution composed of absolute ethyl alcohol, deionized water, ammonia water and cetyltrimethylammonium bromide, the weight ratio is: deionized water: ammonia water: CTAB 250:375:5: x, wherein x is 1-3; the weight percentage concentration of the ammonia water is 28 wt%.
Further, in S2, the solid-liquid weight ratio of the modified Y molecular sieve to the mixed solution is 1 (20-100); preferably 1 (50-100); the weight ratio of the modified Y molecular sieve to the tetraethoxysilane is 1 (0.5-2.5), and preferably 1 (1.0-2.0).
Further, in S2, drying the filter cake obtained after filtering at 60-120 ℃, and then roasting at 350-550 ℃, wherein the drying time is 2-10 hours, and the roasting time is 1-5 hours.
Further, in S3, the organosilane is one of polydimethylsiloxane, polymethylphenylsiloxane, and cyclomethicone.
Further, in S3, the temperature of the oven is set to be 120-250 ℃, and the heating time is 10-60 min.
The invention also provides a core-shell molecular sieve adsorbent for selectively adsorbing VOCs in a high humidity atmosphere, and the adsorbent is prepared by the preparation method.
The invention also provides application of the core-shell molecular sieve adsorbent in selective adsorption of VOCs in a high-humidity atmosphere.
The invention has the beneficial effects that:
(1) before the organosilane is grafted and modified, a layer of mesoporous silicon dioxide (meso-SiO) grows on the outer surface of a Y molecular sieve crystal in advance2) Shell layer to obtain Y @ meso-SiO2Core shell molecular sieves, in this case Y molecular sieves and meso-SiO2Keeping the pore passages between the shell layers to be communicated, and then grafting and depositing organosilane with larger molecular size on the meso-SiO2The shell layer can not cause the pore channel blockage of the outer surface of the Y molecular sieve crystal, and the super-hydrophobic meso-SiO is obtained2The problem that the orifice of the Y molecular sieve is reduced or blocked due to grafting, depositing and modifying of organosilane is solved while the shell S is coated, and in addition, the shell phase Y molecular sieve keeps the original crystallinity, so that higher adsorption capacity is shown;
(2) the invention meso-SiO2The shell layer can provide more abundant Si-OH, and the Si-OH and organic silane are condensed into Si-O-Si bonds, so that grafting modification of the organic silane is better performed;
(3) the invention has reasonable design and convenient operation, and the prepared super-hydrophobic Y @ meso-SiO2the-S core-shell adsorbent can selectively adsorb VOCs in a high humidity atmosphere (relative humidity is more than 60%), has strong practicability and is suitable for popularization.
Description of the drawings:
FIG. 1 is Y @ meso-SiO prepared in accordance with an example of the present invention2TEM images of core shell molecular sieves;
FIG. 2 shows an embodiment of the present inventionExamples Y molecular sieves, Y @ meso-SiO2Core-shell molecular sieve and Y @ meso-SiO2-XRD spectrum of S-1 core shell adsorbent: wherein 1-4 degrees are small-angle XRD, and 5-50 degrees are wide-angle XRD;
FIG. 3 shows Y molecular sieve, Y @ meso-SiO in example of the present invention2-contact angle of S-1 core-shell adsorbent with water.
The specific implementation mode is as follows:
in order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
The invention provides a preparation method of a core-shell molecular sieve adsorbent for selectively adsorbing VOCs (volatile organic compounds) in a high humidity atmosphere, which comprises the steps of firstly growing a mesoporous silica shell layer on the outer surface of a Y-type molecular sieve crystal to obtain Y @ meso-SiO2A core-shell molecular sieve; depositing organosilane on the mesoporous silica shell to obtain a hydrophobic mesoporous silica shell modified by the organosilane, and finally obtaining hydrophobic Y @ meso-SiO2-S core shell adsorbent.
Specifically, the preparation method of the core-shell molecular sieve adsorbent for selectively adsorbing VOCs in a high humidity atmosphere comprises the following steps:
s1, preparation of the modified Y-type molecular sieve:
mixing the Y-type molecular sieve with a poly (diallyldimethylammonium chloride) (PDDA) solution, stirring for 1-6 h at room temperature, then centrifugally washing, and drying at 60-120 ℃ for 2-10 h to obtain a poly (diallyldimethylammonium chloride) (PDDA) modified Y-type molecular sieve; the solid-liquid weight ratio of the Y-type molecular sieve to the poly (diallyldimethylammonium chloride) solution is 1 (20-80), preferably 1 (40-60); the concentration of the poly (diallyldimethylammonium chloride) solution is 0.5-2.0 g/L, preferably 1.0-2.0 g/L.
S2、Y@meso-SiO2Preparing a core-shell molecular sieve:
adding a certain amount of the modified Y-type molecular sieve prepared in S1 into a solution consisting of absolute ethyl alcohol, deionized water, ammonia water and Cetyl Trimethyl Ammonium Bromide (CTAB), and performing ultrasonic dispersion to uniformly disperse the modified Y-type molecular sieve into the mixed solution; then weighing a certain mass of Tetraethoxysilane (TEOS), dropwise adding the TEOS into the mixed solution, and continuously stirring; fully washing and filtering by adopting ethanol and water, drying the filter cake at 60-120 ℃ for 2-10 h, and roasting at 350-550 ℃ for 1-5 h to obtain Y @ meso-SiO2A core-shell molecular sieve; in the solution composed of the absolute ethyl alcohol, the deionized water, the ammonia water and the Cetyl Trimethyl Ammonium Bromide (CTAB), the weight ratio is that the absolute ethyl alcohol: deionized water: ammonia water: CTAB 250:375:5: x, wherein x is 1-3; the weight percentage concentration of the ammonia water is 28 wt%; the solid-liquid weight ratio of the modified Y molecular sieve to the mixed solution is 1 (20-100), preferably 1 (50-100); the weight ratio of the modified Y molecular sieve to the tetraethoxysilane is 1 (0.5-2.5), and preferably 1 (1.0-2.0).
S3 hydrophobic Y @ meso-SiO2-preparation of S core shell adsorbent:
taking a certain amount of Y @ meso-SiO prepared in S22The core-shell molecular sieve is laid on the surface of the glass sheet, suspended in the air and placed in a closed glass container containing organosilane (polydimethylsiloxane), and then the glass container is placed in an oven at 120-250 ℃ and heated for 10-60 min; after cooling, the super-hydrophobic Y @ meso-SiO is obtained2-S core shell adsorbent.
The invention also provides a core-shell molecular sieve adsorbent for selectively adsorbing VOCs in a high humidity atmosphere, and the adsorbent is prepared by the preparation method.
The core-shell molecular sieve adsorbent can be widely applied to the field of selective adsorption of VOCs in a high humidity atmosphere.
Example 1
S1, preparation of the modified Y-type molecular sieve:
mixing the Y molecular sieve with 1.0g/L poly (diallyldimethylammonium chloride) (PDDA) solution at a solid-liquid mass ratio of 1:60, stirring at room temperature for 2.0h, then centrifugally washing, and drying at 100 ℃ for 10h to obtain the PDDA modified Y molecular sieve;
S2、Y@meso-SiO2preparing a core-shell molecular sieve:
adding 20g of PDDA modified Y molecular sieve into a solution (mass ratio of absolute ethyl alcohol to deionized water: 28 wt% of ammonia water: CTAB: 250:375:5:2) composed of 28 wt% of ammonia water, Cetyl Trimethyl Ammonium Bromide (CTAB), anhydrous ethanol and deionized water, wherein the solid-liquid mass ratio is 1:50, and performing ultrasonic dispersion to uniformly disperse the molecular sieve in the mixed solution; then 20g of tetraethoxysilane is weighed and is added into the mixed solution drop by drop, and the mixture is continuously stirred for 3 hours; then washing and filtering with deionized water, drying the filter cake at 100 ℃ for 10h, and roasting at 500 ℃ for 3h to obtain Y @ meso-SiO2A core-shell molecular sieve. As shown in FIG. 1, a layer of meso-SiO grows on the outer surface of the Y molecular sieve by adopting a transmission electron microscope TEM2A shell layer;
s3 hydrophobic Y @ meso-SiO2-preparation of S core shell adsorbent:
taking 5g Y @ meso-SiO2The core-shell molecular sieve is laid on the surface of the glass sheet, suspended in the air and placed in a closed glass container filled with polydimethylsiloxane, and then the glass container is placed in a 200 ℃ oven to be heated for 30 min; after cooling, the super-hydrophobic Y @ meso-SiO is obtained2-S core-shell adsorbent, denoted as Y @ meso-SiO2-S-1。
FIG. 2 shows Y molecular sieve, Y @ meso-SiO2Core-shell molecular sieve and Y @ meso-SiO2-XRD spectrum of S-1: wherein, the angle of 1-4 degrees is small-angle XRD, and the angle of 5-50 degrees is wide-angle XRD. The small-angle XRD result shows that the diffraction peak at 2.4 degrees is attributed to meso-SiO2The (100) crystal face of (a) indicates the existence of an ordered mesoporous structure. The wide-angle XRD shows that meso-SiO2The growth of the shell layer and the grafting and deposition process of the organosilane do not influence the crystal structure of the Y molecular sieve. FIG. 3 shows Y molecular sieve and Y @ meso-SiO2-water contact angle of the surface of the S-1 sample. The contact angle of water drops on the surface of the Y molecular sieve is 24 degrees, which shows that the hydrophobicity of the Y molecular sieve is poor; and Y @ meso-SiO2The contact angle of-S-1 with water was 115 °, indicating passage through meso-SiO2And Y @ meso-SiO prepared after grafting and depositing of organosilane2The S-1 adsorbent has excellent hydrophobic properties.
Example 2
S1, preparation of the modified Y-type molecular sieve:
mixing the Y molecular sieve with 1.5g/L poly (diallyldimethylammonium chloride) (PDDA) solution at a solid-liquid mass ratio of 1:50, stirring at room temperature for 2.0h, centrifuging, washing, and drying at 120 ℃ for 8h to obtain a PDDA modified Y molecular sieve;
S2、Y@meso-SiO2preparing a core-shell molecular sieve:
adding 20g of PDDA modified Y molecular sieve into a solution (mass ratio of absolute ethyl alcohol to deionized water: 28 wt% of ammonia water: CTAB: 250:375:5:3) composed of 28 wt% of ammonia water, Cetyl Trimethyl Ammonium Bromide (CTAB), anhydrous ethanol and deionized water, wherein the solid-liquid mass ratio is 1:100, and uniformly dispersing the molecular sieve in the mixed solution by ultrasonic dispersion; then weighing 30g of ethyl orthosilicate, dropwise adding the ethyl orthosilicate into the mixed solution, and continuously stirring for 3 hours; then washing and filtering with deionized water, drying the filter cake at 110 ℃ for 10h, and roasting at 500 ℃ for 3h to obtain Y @ meso-SiO2A core-shell molecular sieve;
s3 hydrophobic Y @ meso-SiO2-preparation of S core shell adsorbent:
taking 5g Y @ meso-SiO2The core-shell molecular sieve is laid on the surface of the glass sheet, suspended in a closed glass container containing cyclomethicone, and then the glass container is placed in a 200 ℃ oven to be heated for 30 min; after cooling, the super-hydrophobic Y @ meso-SiO is obtained2-S core-shell adsorbent, denoted as Y @ meso-SiO2-S-2。
Example 3
S1, preparation of the modified Y-type molecular sieve:
mixing the Y molecular sieve with 2.0g/L poly (diallyldimethylammonium chloride) (PDDA) solution at a solid-liquid mass ratio of 1:40, stirring at room temperature for 2.0h, then centrifugally washing, and drying at 80 ℃ for 8h to obtain the PDDA modified Y molecular sieve;
S2、Y@meso-SiO2preparing a core-shell molecular sieve:
20g of PDDA-modified Y fraction were takenAdding the sub-sieve into a solution consisting of 28 wt% of ammonia water, Cetyl Trimethyl Ammonium Bromide (CTAB), absolute ethyl alcohol and deionized water (the mass ratio of the absolute ethyl alcohol to the deionized water: 28 wt% of ammonia water: CTAB is 250:375:5:1.0), wherein the solid-liquid mass ratio is 1:80, and performing ultrasonic dispersion to uniformly disperse the molecular sieve in the mixed solution; then weighing 40g of ethyl orthosilicate, dropwise adding the ethyl orthosilicate into the mixed solution, and continuously stirring for 3 hours; then washing and filtering with deionized water, drying the filter cake at 110 ℃ for 10h, and roasting at 500 ℃ for 3h to obtain Y @ meso-SiO2A core-shell molecular sieve;
s3 hydrophobic Y @ meso-SiO2-preparation of S core shell adsorbent:
taking 5g Y @ meso-SiO2The core-shell molecular sieve is laid on the surface of the glass sheet, suspended in the air and placed in a closed glass container filled with polydimethylsiloxane, and then the glass container is placed in a 250 ℃ oven to be heated for 10 min; after cooling, the super-hydrophobic Y @ meso-SiO is obtained2-S core-shell adsorbent, denoted as Y @ meso-SiO2-S-3。
Comparative example 1:
preparation of comparative sample:
spreading a 5g Y molecular sieve on the surface of a glass sheet, suspending the glass sheet in a closed glass container containing polydimethylsiloxane, and then placing the glass container in an oven at 200 ℃ for heating for 30 min; and cooling to obtain the organosilane grafting modified Y-S adsorbent, which is marked as Y-S-1.
Comparative example 2:
preparation of comparative sample:
spreading a 5g Y molecular sieve on the surface of a glass sheet, suspending the glass sheet in a closed glass container containing cyclomethicone, and then placing the glass container in an oven at 200 ℃ for heating for 30 min; and cooling to obtain the organosilane grafting modified Y-S adsorbent, which is marked as Y-S-2.
Comparative example 3:
preparation of comparative sample:
spreading a 5g Y molecular sieve on the surface of a glass sheet, suspending the glass sheet in a closed glass container containing polydimethylsiloxane, and then placing the glass container in an oven at 250 ℃ for heating for 10 min; and cooling to obtain the organosilane grafting modified Y-S adsorbent, which is marked as Y-S-3.
Compare the dynamic VOCs adsorption performance of the molecular sieve adsorbent prepared by the embodiment and the comparative example under the atmosphere of different humidity, and carry out on a laboratory self-built adsorption device, wherein the adsorption device comprises: VOCs and humidity generation system, gas flow control system, adsorbent bed and analysis and detection system.
Tabletting the Y molecular sieve and Y @ meso-SiO2-S core-shell adsorbent (Y @ meso-SiO)2-S-1、Y@meso-SiO2-S-2 and Y @ meso-SiO2-S-3) and Y-S adsorbent (Y-S-1, Y-S-2 and Y-S-3) powders are pressed into a sheet shape and then sieved into 20-40 mesh particles; respectively filling 1.0g of the three adsorbent particles in the middle of an adsorption bed, taking toluene as a probe molecule, and keeping the concentration of the toluene at 1200mg/m at 25 DEG C3The gas flow rate is 250mL/min, the relative humidity RH is 0, RH is 60% and RH is 80%, dynamic adsorption experiments are carried out, the concentration of toluene at the upstream and downstream of the adsorption bed layer is detected by gas chromatography, and the adsorption capacity is calculated by the following formula:
Figure BDA0002807603740000081
wherein Q represents the adsorption capacity, F represents the gas flow rate, C0Denotes the upstream concentration of the adsorbent bed, CiRepresenting the downstream concentration of the adsorbent bed, w representing the mass of adsorbent packing, tsIndicating the time for the adsorption to reach dynamic equilibrium.
As shown in table 1, it can be seen from table 1 that the unmodified Y molecular sieve exhibits excellent adsorption performance in a dry environment, but the adsorption capacity of the Y molecular sieve is only 12.73mg/g under the condition that RH is 60%, indicating that the hydrophobicity is poor; for Y @ meso-SiO2the-S core-shell adsorbent shows excellent adsorption performance under the conditions of RH (0), RH (60) and RH (80), and the adsorption capacity does not change greatly under different relative humidities, which shows that the adsorbent passes through meso-SiO2And Y @ meso-SiO prepared after grafting and depositing of organosilane2The S adsorbent has better hydrophobic property; and the Y-S adsorption prepared by directly grafting and depositing organosilane on the Y molecular sieveAgents which are relatively hydrophobic but have an adsorption performance lower than Y @ meso-SiO2The main reason of the S core-shell adsorbent is that the organic silane grafting deposition blocks the orifice of the outer surface of the Y molecular sieve, so that the adsorption performance of the Y molecular sieve is reduced.
TABLE 1 toluene adsorption capacity of adsorbents at different relative humidities
Figure BDA0002807603740000082
Before grafting modification of organosilane, a layer of mesoporous silicon dioxide (meso-SiO) grows on the outer surface of a Y molecular sieve crystal in advance2) Shell layer to obtain Y @ meso-SiO2Core shell molecular sieves, in this case Y molecular sieves and meso-SiO2The pore passages between the shell layers are kept through; then selecting organosilane with larger molecular size, such as polydimethylsiloxane, and selectively depositing on meso-SiO by Chemical Vapor Deposition (CVD)2A shell layer can not cause the blockage of pore channels on the outer surface of the Y molecular sieve crystal, and an organosilane modified hydrophobic mesoporous silica shell layer (meso-SiO)2-S), finally obtaining the hydrophobic Y @ meso-SiO2the-S core-shell adsorbent solves the problem of reduction or blockage of the orifice of the Y molecular sieve caused by grafting, depositing and modifying organosilane. The invention has reasonable design and convenient operation, and the prepared super-hydrophobic Y @ meso-SiO2the-S core-shell adsorbent can selectively adsorb VOCs in a high humidity atmosphere, is high in practicability and is suitable for popularization.
The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention, it should be noted that, for those skilled in the art, several modifications and decorations without departing from the principle of the present invention should be regarded as the protection scope of the present invention.

Claims (10)

1. A preparation method of a core-shell molecular sieve adsorbent for selectively adsorbing VOCs in a high humidity atmosphere is characterized in that firstly, the core-shell molecular sieve adsorbent is preparedGrowing a mesoporous silica shell layer on the outer surface of the Y-type molecular sieve crystal to obtain Y @ meso-SiO2A core-shell molecular sieve; depositing organosilane on the mesoporous silica shell to obtain a hydrophobic mesoporous silica shell modified by the organosilane, and finally obtaining hydrophobic Y @ meso-SiO2-S core shell adsorbent.
2. The preparation method of the core-shell molecular sieve adsorbent for selectively adsorbing VOCs in high humidity atmosphere according to claim 1, characterized by comprising the following steps:
s1, preparation of the modified Y-type molecular sieve:
mixing the Y-type molecular sieve with a poly (diallyldimethylammonium chloride) solution, stirring at room temperature, and then centrifugally washing and drying to obtain the poly (diallyldimethylammonium chloride) -modified Y-type molecular sieve;
S2、Y@meso-SiO2preparing a core-shell molecular sieve:
adding a certain amount of the modified Y-type molecular sieve prepared in S1 into a mixed solution consisting of absolute ethyl alcohol, deionized water, ammonia water and hexadecyl trimethyl ammonium bromide, and performing ultrasonic dispersion to uniformly disperse the modified Y-type molecular sieve into the mixed solution; then weighing a certain mass of ethyl orthosilicate, dropwise adding the ethyl orthosilicate into the mixed solution, and continuously stirring; then, ethanol and water are adopted for full washing and filtration, and a filter cake is dried and roasted to obtain Y @ meso-SiO2A core-shell molecular sieve;
s3 hydrophobic Y @ meso-SiO2-preparation of S core shell adsorbent:
taking a certain amount of Y @ meso-SiO prepared in S22The core-shell molecular sieve is laid on the surface of the glass sheet, suspended in the air and placed in a closed glass container containing organosilane, and then the glass container is placed in an oven to be heated; after cooling, the super-hydrophobic Y @ meso-SiO is obtained2-S core shell adsorbent.
3. The preparation method of the core-shell molecular sieve adsorbent for selectively adsorbing VOCs under high humidity atmosphere according to claim 2, wherein in S1, the solid-liquid weight ratio of the Y-type molecular sieve to the poly (diallyldimethylammonium chloride) solution is 1 (20-80); wherein the concentration of the poly (diallyldimethylammonium chloride) solution is 0.5-2.0 g/L.
4. The preparation method of the core-shell molecular sieve adsorbent for selectively adsorbing VOCs in high humidity according to claim 2, wherein the S1 is stirred for 1-6 h, centrifugally washed, and dried at 60-120 ℃ for 2-10 h.
5. The method according to claim 2, wherein in step S2, the weight ratio of the mixed solution of absolute ethanol, deionized water, ammonia water and cetyltrimethylammonium bromide is absolute ethanol: deionized water: ammonia water: CTAB 250:375:5: x, wherein x is 1-3; the weight percentage concentration of the ammonia water is 28 wt%; the solid-liquid weight ratio of the modified Y molecular sieve to the mixed solution is 1 (20-100); the weight ratio of the modified Y molecular sieve to the tetraethoxysilane is 1 (0.5-2.5).
6. The preparation method of the core-shell molecular sieve adsorbent for selectively adsorbing VOCs in high humidity according to claim 2, wherein in S2, a filter cake obtained after filtration is dried at 60-120 ℃, and then roasted at 350-550 ℃, wherein the drying time is 2-10 h, and the roasting time is 1-5 h.
7. The method according to claim 2, wherein in S3, the organosilane is one of polydimethylsiloxane, polymethylphenylsiloxane, and cyclomethicone.
8. The preparation method of the core-shell molecular sieve adsorbent for selectively adsorbing VOCs in high humidity according to claim 2, wherein in S3, the oven temperature is set to 120-250 ℃, and the heating time is 10-60 min.
9. A core-shell molecular sieve adsorbent for selectively adsorbing VOCs in a high humidity atmosphere, which is characterized by being prepared by the preparation method of any one of claims 1-8.
10. The use of the core-shell molecular sieve adsorbent of any one of claims 1 to 8 in selective adsorption of VOCs in a high humidity atmosphere.
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