Modified molecular sieve capable of adsorbing and regenerating high-boiling-point substances and preparation method thereof

Abstract

The invention discloses a modified molecular sieve capable of adsorbing and regenerating high-boiling-point substances and a preparation method thereof. According to the molecular sieve, a tetrapropylammonium bromide and N-bromoacetamide double-template system is adopted, a high-silicon ZSM-5 molecular sieve with the silica-alumina ratio larger than 300 is prepared through a guided gel-assisted hydrothermal synthesis method, and Ni metal is loaded for modification. The product has excellent hydrophobicity (the water contact angle is greater than 120 degrees) and a mesoporous structure, and can efficiently adsorb macromolecular organic matters such as coal tar and the like. Ni2 + / NiO bifunctional sites are innovatively introduced, adsorption selectivity is enhanced through pi-complexation, low-temperature desorption assisted by ethanol at the temperature of 80-120 DEG C is realized, and the desorption rate is increased by 3-5 times. Compared with a traditional method, the technology has the advantages of cheap raw materials, high crystallinity (greater than 95%), carbon deposition resistance, cyclic regeneration and the like, and is suitable for resourceful treatment of high-boiling-point organic matters in industrial waste gas.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of molecular sieve preparation, and particularly relates to a modified molecular sieve capable of adsorbing and regenerating high-boiling-point substances and a preparation method thereof. BACKGROUND

[0002] High-boiling-point substances such as coal tar generated by industrial waste gas can be cracked into light polycyclic or small-molecule organic substances to realize waste resource utilization. Traditional microporous molecular sieves have small pore sizes, low adsorption efficiency for high-boiling-point macromolecules (such as polymer monomers and polycyclic aromatic hydrocarbons), and slow diffusion rate. Through adsorption by the molecular sieve and then high-temperature heating (400-800℃) under oxygen-free or oxygen-deficient conditions, the organic substances in the industrial waste gas are decomposed into combustible gas, bio-oil and carbon residue, realizing reduction (reduction of more than 70%), harmlessness (killing of pathogens and degradation of pollutants) and resource utilization (energy recovery and carbon material utilization). Compared with incineration, it has lower emissions; compared with landfill, it can greatly reduce land occupation and secondary pollution, and is particularly suitable for high-boiling-point macromolecular substances such as coal tar, and conforms to the trend of sustainable waste management.

[0003] The existing process needs to consume additional heat energy and hydrogen source for catalytic hydrogenation of the condensed tar. Pyrolysis of coal mixed with a catalyst can realize in-situ catalytic upgrading of coal pyrolysis tar, but it is difficult to separate the pyrolysis coke from the catalyst, which affects the industrial application of the catalyst. The catalytic pyrolysis technology can further crack the sludge pyrolysis tar into small molecules by adding a catalyst, thereby realizing the lightening of the pyrolysis products. Molecular sieve catalysts are concerned due to their advantages of strong catalytic cracking ability of heavy components and high light aromatic yield. In China, light aromatic products are mainly derived from the reforming and cracking of coal and petroleum. With the continuous consumption and depletion of fossil energy, the production of light aromatics from renewable biomass has become a new direction for researchers at home and abroad. SUMMARY

[0004] In view of the deficiencies in the prior art, the present application aims to provide a modified molecular sieve capable of adsorbing and regenerating high-boiling-point substances and a preparation method thereof. To achieve the object of the present application, the following technical solutions are adopted: The modified molecular sieve capable of adsorbing and regenerating high-boiling-point substances uses the following raw materials: NaOH 6.6-11 parts; tetrapropylammonium bromide 9-11 parts; silica sol 120-130 parts; N-bromoacetamide 3-4 parts; aluminum sulfate 0.1-0.3 parts; and deionized water 175-246 parts. The present application also provides a preparation method of the aforementioned modified molecular sieve capable of adsorbing and regenerating high-boiling-point substances, comprising the following steps: 1) Dissolve NaOH in deionized water. After it is completely dissolved, add tetrapropylammonium bromide and stir until the solution is clear. Finally, add silica sol and stir continuously for 1 hour to form a uniform gel solution. The prepared gel solution is aged at 30°C for 24 hours and dissolved in deionized water to obtain a guided gel. 2) Dissolve NaOH in deionized water, add silica sol after it is completely dissolved and stir evenly, reflux and stir in a constant temperature water bath at 80°C for 1 hour to obtain alkali-treated silica sol; 3) Add NaOH to deionized water. Once completely dissolved, add N-bromoacetamide and aluminum sulfate, stirring until completely dissolved. Then add the alkali-treated silica sol obtained in 2) and continue stirring until homogeneous to obtain a uniform gel. 4) adding 1.0 g of the guiding gel obtained in 1) to the uniform gel obtained in 3) at a ratio of 1.0 g of SiO2 to 100.0 mg of the guiding gel, and subjecting the resulting gel solution to dynamic crystallization at 90°C for 6 hours, then heating to 170°C for dynamic crystallization for 24 hours. After completion of the crystallization, the template was removed by centrifugal filtration, washing, drying, and calcination to obtain a high-silica ZSM-5 molecular sieve; 5) The molecular sieve obtained in 4) was placed in an alumina crucible in a muffle furnace and calcined at 550°C for 5 hours. After cooling to room temperature, the crucible was removed and, using a wet impregnation method, 1.460 g of Ni(NO₃)₂·6H₂O was dissolved in deionized water to prepare a 200 mL solution. 10 g of the calcined ZSM-5 was added to the solution and stirred in an 80°C water bath for 5 hours until the water was completely evaporated. The metal-modified ZSM-5 was removed and dried in a forced air drying oven for 24 hours. The metal-modified ZSM-5 was pre-activated again and then ground and sieved to obtain the final product.

[0005] Preferably, in a method for preparing a modified adsorbable regenerable high-boiling point substance molecular sieve, the raw materials used in 1) are 0.6-1.0 parts by weight of NaOH; 35-40 parts by weight of deionized water; 9-11 parts by weight of tetrapropylammonium bromide; and 45-50 parts by weight of silica sol.

[0006] Preferably, in a method for preparing a modified adsorbable regenerable high-boiling-point substance molecular sieve, the raw materials used in 3) are as follows: 1-2 parts of NaOH; 70-80 parts of deionized water; 3-4 parts of N-bromoacetamide; 0.1-0.3 parts of aluminum sulfate; and 100-105 parts of alkali-treated silica sol.

[0007] Preferably, in a method for preparing a modified molecular sieve capable of adsorbing and regenerating high-boiling-point substances, the metal loading in 5) is 3% of the mass of the high-silicon ZSM-5 molecular sieve.

[0008] Reaction process: 1) Adsorption: The modified adsorbable regenerated high-boiling-point substance molecular sieve described above is filled in a fixed bed adsorption tower, and a petroleum distillate containing aromatic hydrocarbons, such as reformate, is introduced, under the condition that the temperature is 20-80℃, the aromatic hydrocarbons are preferentially adsorbed, and the non-aromatic hydrocarbons directly pass through; 2) Regeneration: Under the condition that the temperature is 80-120℃, ethanol is sprayed in the form of atomization to the surface of the saturated molecular sieve in a closed environment, and the amount is about 1-2 mL / g of the molecular sieve; the ethanol vapor is circulated in the closed system to improve the recovery rate; after completion, the residual ethanol is purged with nitrogen at 50℃ for 0.5h to avoid the decline of the subsequent adsorption performance.

[0009] Reaction principle: The reaction temperature is 60℃, sodium hydroxide provides an alkaline environment, and by controlling the hydrolysis and polycondensation of silica sol, the nucleation and crystallization rate of the molecular sieve is controlled to form a gel network structure. The molecular structure of tetrapropyl ammonium bromide (TPABr) acts as a template agent due to its "cross-shaped" stereostructure, allowing the composite micelles to guide the arrangement of silicate framework around it during high-temperature crystallization, ultimately forming a cross-channel system gel system of ZSM-5. The hydrophobic propyl chain of TPABr combines with silicate species through electrostatic interaction and van der Waals force to form "organic-inorganic composite micelles". N-bromacetamide acts as an auxiliary template agent and cooperates with tetrapropyl ammonium bromide to decompose and form gas during high-temperature crystallization, assisting in the formation of mesoporous structures and optimizing the pore structure. Aluminum sulfate provides the aluminum source to introduce the acid sites of the molecular sieve framework, enhancing the adsorption and catalytic functions; its content is very low, and the purpose is to form a high silicon-aluminum ratio to improve the thermal stability and hydrophobicity of the molecular sieve. Silica sol provides the main component of the molecular sieve framework, forming a high-silicon ZSM-5 molecular sieve to enhance hydrophobicity and make it easier to adsorb high-boiling-point organic molecules. Deionized water acts as a solvent to promote the uniform mixing of the raw materials and the formation of the gel. The specific pore structure of ZSM-5 (two-dimensional ten-membered ring structure) is removed during the calcination stage, leaving microporous channels. Ni 2+ is loaded onto the molecular sieve by impregnation method. The empty orbit of Ni 2+ interacts with the π electron cloud of the benzene ring to form a coordination bond, improving the selectivity of high-boiling-point substances such as condensed ring aromatic hydrocarbons, and can also combine with the lone pair of sulfur to selectively remove sulfur such as thiophene, and catalyze the decomposition and conversion of adsorbates under high temperature and oxygen conditions.

[0010] The beneficial effects of the present application are: (1) High-silicon ZSM-5 molecular sieve has high lipophilicity and hydrophobicity, and can maintain excellent high-boiling point substance adsorption capacity in high humidity environment. The present application adopts a tetrapropyl ammonium bromide+N-bromoacetamide double template system, tetrapropyl ammonium bromide ensures the formation of two-dimensional ten-membered ring structure framework, avoids impurities, and N-bromoacetamide assists the formation of mesopores to improve the diffusion capacity of macromolecules. The pre-crystallization directing gel is added before conventional hydrothermal synthesis, which significantly improves the crystallinity (XRD shows that the crystallinity is >95%). Alkaline treatment of silica sol optimization: by adjusting the reactivity of the silicon source with NaOH, the final product has a silicon aluminum ratio >300 and a hydrophobicity (water contact angle >120°) far exceeding that of commercial ZSM-5 (Si / Al ≈ 50) (2) Unlike ordinary molecular sieves that can only physically adsorb, the present application introduces Ni 2+ The regeneration of the dual-function catalytic mechanism requires high temperature (>400℃) or solvent cleaning, which is high in energy consumption and easy to deactivate, and Ni 2+ Through π-complexation, high-boiling point substances are preferentially captured, NiO catalytically oxidizes and decomposes the adsorbate, and has anti-carbon deposition characteristics, improving the regeneration efficiency.

[0011] (3) Unlike traditional temperature programmed desorption method, the temperature programmed desorption method has slow heating speed and high cost, the present application adopts ethanol wet desorption, which can be completed at 80-120℃, ethanol molecules fill the pores, reduce the diffusion resistance of organic matter, and the desorption rate is increased by 3-5 times, and the weak reducing property of ethanol can prevent Ni 2+ from being over-oxidized (4) The raw materials are cheap and easy to obtain, unlike traditional template agents such as pure tetramethylammonium hydroxide, which are expensive and easy to form amorphous silicon impurities, and have a long crystallization time (>72h). The preparation of N-bromoacetamide is usually carried out at 0-25℃, without the need for high temperature and high pressure equipment, which is suitable for industrial production, and can be stored for a long time under dry conditions, without the risk of fluorine pollution, in line with the trend of green chemistry. DETAILED DESCRIPTION

[0012] The following examples are only used to illustrate the content of the present application, and do not limit the protection scope of the present application. Simple changes to the present application using the concept of the present application are within the scope of protection claimed by the present application.

[0013] The sources of the materials in the following examples and comparative examples are as follows: NaOH: Shanghai Aladdin Bio-Science Co., Ltd.; Tetrapropyl ammonium bromide; Liaoning Kelong Fine Chemical Co., Ltd.; Silica sol: Shanghai Hengsheng Chemical Co., Ltd. (industrial grade); N-bromoacetamide 3-4 parts; Shanghai Aladdin Bio-Science Co., Ltd.; Aluminum sulfate: Shanghai Aladdin Bio-Science Co., Ltd.; Deionized water: self-made.

[0014] Examples 1-5, Comparative Examples 1-4 all used the same synthesis method of the modified adsorbable and regenerable high-boiling-point substance molecular sieve as described in the invention content.

[0015] Example 1 1) 0.6 parts of NaOH was dissolved in 35 parts of deionized water, after complete dissolution, 9 parts of tetrapropylammonium bromide was added, stirred until the solution was clear, finally 45 parts of silica sol was added, continuously stirred for 1 h to form a uniform gel solution, the prepared gel solution was aged at 30℃ for 24 h, and the deionized water was dissolved to obtain a directing gel; 2) 5 parts of NaOH was dissolved in 120 parts of deionized water, after complete dissolution, 75 parts of silica sol was added and stirred uniformly, and an alkali-treated silica sol was obtained by refluxing and stirring for 1 h in a 80℃ constant temperature water bath; 3) 1 part of NaOH was added to 70 parts of deionized water, after complete dissolution, 3 parts of N-bromoacetamide and 0.1 part of aluminum sulfate were added respectively, stirred until completely dissolved, then 100 parts of the alkali-treated silica sol obtained in 2) was added, continuously stirred until uniform, to obtain a uniform gel; 4) According to the proportion of 1.0 g SiO2 adding 100.0 mg directing gel, 1.0 g directing gel obtained in 1) was added to the uniform gel obtained in 3), the obtained gel liquid was dynamically crystallized at 90℃ for 6 h, and then the temperature was raised to 170℃ for dynamic crystallization for 24 h; After crystallization, the template was removed by centrifugal filtration, washing, drying and calcination to obtain high-silicon ZSM-5 molecular sieve; 5) The molecular sieve obtained in 4) was placed in an alumina crucible and put into a muffle furnace, calcined at 550℃ for 5 h, and then taken out after cooling to room temperature; A solution of 1.460 g Ni(NO3)2·6H2O in deionized water was prepared by wet impregnation method; 10 g of calcined ZSM-5 was added to the solution, stirred in a 80℃ water bath for 5 h, to obtain a paste-like metal-modified ZSM-5; The metal-modified ZSM-5 was taken out and dried in a blast drying oven for 24 h, then ground and sieved after activation pretreatment, to obtain the final product.

[0016] Example 2 1) 1 part of NaOH was dissolved in 40 parts of deionized water, after complete dissolution, 11 parts of tetrapropylammonium bromide was added, stirred until the solution was clear, finally 50 parts of silica sol was added, continuously stirred for 1 h to form a uniform gel solution, the prepared gel solution was aged at 30℃ for 24 h, and the deionized water was dissolved to obtain a directing gel; 2) 8 parts of NaOH was dissolved in 126 parts of deionized water, after complete dissolution, 85 parts of silica sol was added and stirred uniformly, and an alkali-treated silica sol was obtained by refluxing and stirring for 1 h in a 80℃ constant temperature water bath; 3) 2 parts of NaOH were added to 80 parts of deionized water, after complete dissolution, 4 parts of N-bromoacetamide and 0.3 parts of aluminum sulfate were added respectively, stirred until completely dissolved, then 105 parts of the alkali-treated silica sol obtained in 2) was added, continuously stirred until uniform, to obtain a uniform gel; 4) 1.0 g of the directing gel obtained in 1) was added to the uniform gel obtained in 3) at a ratio of 100.0 mg of directing gel per 1.0 g of SiO2, the obtained gel liquid was dynamically crystallized at 90°C for 6h, and then the temperature was increased to 170°C for dynamic crystallization for 24h; after the crystallization was completed, the template was removed by centrifugal filtration, washing, drying and calcination to obtain a high-silicon ZSM-5 molecular sieve; 5) The molecular sieve obtained in 4) was placed in an alumina crucible and placed in a muffle furnace, calcined at 550°C for 5h, and then taken out after cooling to room temperature; 1.460g of Ni(NO3)2·6H2O was dissolved in deionized water to prepare a 200mL solution by wet impregnation method; 10g of the calcined ZSM-5 was added to the solution, and stirred in a 80°C water bath for 5h to obtain a paste-like metal-modified ZSM-5; the metal-modified ZSM-5 was taken out and placed in a blast drying oven for drying for 24h, and then ground and sieved after activation pretreatment again to obtain the final product.

[0017] Example 3 1) 0.8 parts of NaOH were dissolved in 38 parts of deionized water, after complete dissolution, 10 parts of tetrapropylammonium bromide were added, stirred until the solution was clear, and finally 47 parts of silica sol were added, continuously stirred for 1h to form a uniform gel solution, and the prepared gel solution was aged at 30°C for 24h to obtain a directing gel dissolved in deionized water; 2) 6.5 parts of NaOH were dissolved in 123 parts of deionized water, after complete dissolution, 780 parts of silica sol were added and stirred uniformly, and then refluxed and stirred at 80°C for 1h to obtain an alkali-treated silica sol; 3) 1.5 parts of NaOH were added to 75 parts of deionized water, after complete dissolution, 3.5 parts of N-bromoacetamide and 0.2 parts of aluminum sulfate were added respectively, stirred until completely dissolved, then 103 parts of the alkali-treated silica sol obtained in 2) was added, continuously stirred until uniform, to obtain a uniform gel; 4) 1.0 g of the directing gel obtained in 1) was added to the uniform gel obtained in 3) at a ratio of 100.0 mg of directing gel per 1.0 g of SiO2, the obtained gel liquid was dynamically crystallized at 90°C for 6h, and then the temperature was increased to 170°C for dynamic crystallization for 24h; after the crystallization was completed, the template was removed by centrifugal filtration, washing, drying and calcination to obtain a high-silicon ZSM-5 molecular sieve; 5) Put the molecular sieve obtained in 4) into an alumina crucible and place it in a muffle furnace, calcine at 550°C for 5h, and after cooling to room temperature, take it out, and use a wet impregnation method to dissolve 1.460g Ni(NO3)2·6H2O in deionized water to prepare a 200mL solution; add 10g of the calcined ZSM-5 to the solution, and stir in a water bath at 80°C for 5h to obtain a paste-like metal-modified ZSM-5; take out the metal-modified ZSM-5 and place it in a blast drying oven for drying for 24h, and after re-activation pretreatment, grind and sieve to obtain the final product.

[0018] Example 4 Compared with Examples 1-3, the difference of Example 4 is that the proportion of raw materials is changed: in Step 1), the proportion of raw materials is NaOH 0.6 parts; deionized water 40 parts; tetrapropylammonium bromide 9 parts; silica sol 50 parts. In Step 2), the proportion of raw materials is NaOH 8 parts; deionized water 120 parts; silica sol 85 parts. In Step 3), the proportion of raw materials is NaOH 1 part; deionized water 80 parts; N-bromoacetamide 3 parts; aluminum sulfate 0.3 parts; alkali-treated silica sol 100 parts.

[0019] Example 5 Compared with Examples 1-3, the difference of Example 5 is that the proportion of raw materials is changed: in Step 1), the proportion of raw materials is NaOH 1 part; deionized water 35 parts; tetrapropylammonium bromide 11 parts; silica sol 45 parts. In Step 2), the proportion of raw materials is NaOH 5 parts; deionized water 126 parts; silica sol 75 parts. In Step 3), the proportion of raw materials is NaOH 2 parts; deionized water 70 parts; N-bromoacetamide 4 parts; aluminum sulfate 0.1 parts; alkali-treated silica sol 105 parts.

[0020] Comparative Example 1 Commercially available molecular sieve that can adsorb and regenerate high-boiling substances.

[0021] Comparative Example 2 Basically the same as Example 1, except that tetrapropylammonium bromide is not used.

[0022] Comparative Example 3 Basically the same as Example 1, except that N-bromoacetamide is not used.

[0023] Comparative Example 4 Basically the same as Example 1, except that metal Ni is not loaded.

[0024] Examples 1-5 and Comparative Examples 1-4 are all tested as follows: 1. Adsorption capacity test (1) Dynamic breakthrough experiment (simulating industrial waste gas) Apparatus: Fixed bed reactor (inner diameter 10 mm, bed height 10 cm).

[0025] Test conditions: Space velocity (GHSV): 2000 h -1 , temperature 150°C (simulated waste gas conditions); Relative humidity: 30%; The simulated waste gas was passed through the molecular sieve for adsorption, and then the initial concentration Co of the coal tar was measured by gas chromatography (GC-FID / SCD): FID (flame ionization detector), and the concentration of the coal tar in the outlet gas was monitored in real time by Fourier transform infrared spectroscopy (FTIR).

[0026] The breakthrough time (when the outlet concentration reaches 5% of the inlet) and the saturation time (when the outlet concentration reaches 90%) were recorded.

[0027] The dynamic adsorption capacity was calculated: q br = (Co · Q · t br ) / m (Co: inlet coal tar concentration (mg / m³) Q: gas flow rate (m³ / h) t br : breakthrough time (h) m: molecular sieve mass (g); (2) Static adsorption test 50 mg of molecular sieve was weighed on an electronic balance and added to 50 mL of aqueous xylene solution (100 ppm), and shaken at 25°C for 2 hours. After filtration, the remaining concentration was measured by ultraviolet spectrophotometry, and the adsorption capacity was calculated: Q = (C o - C e ) x 50 mL / 50 mg.

[0028] (3) Competitive adsorption test The simulated industrial waste gas of xylene + toluene + water vapor + SO2 was passed in, and the selective adsorption capacity was tested in the mixed gas. The breakthrough time and adsorption capacity were tested under the conditions of RH 80%, toluene 200 ppm, space velocity = 2000 h -1 .

[0029] 2. Hydrophobicity verification (1) Water droplet contact angle test: The prepared molecular sieve was pressed into a tablet, 2 μL of deionized water was dropped, a micro lens was used to take a photo, and the angle was measured by a protractor software. Greater than 120° was qualified.

[0030] 3. Determination of specific surface area and pore structure (1) N2 adsorption-desorption method: First, the sample is pretreated: molecular sieve powder (about 100-200 mg) is loaded into a sample tube, vacuum degassed at 300°C for 6-8 hours to remove surface adsorbed water and impurities. Then the sample tube is immersed in liquid nitrogen (77K), and N2 gas is gradually introduced, and the adsorption amount at different pressures (P / Po range 0.05-0.3) is recorded. After the adsorption is completed, the pressure is gradually reduced to record the desorption curve. The degassing temperature should be lower than the thermal stability limit of the molecular sieve to avoid structure collapse; ensure that P / Po is in the range of 0.05-0.3 to ensure good linearity to ensure the effectiveness of BET.

[0031] where Vm is the monolayer adsorption amount, the specific surface area (SBET= Vm·N A ·σN2) 4. Regeneration performance test (1) Cycle regeneration test: under the condition of 80-120°C, in a closed environment, ethanol is sprayed in atomized form to the surface of the saturated molecular sieve, with a dosage of about 1-2 mL / g of molecular sieve; the ethanol vapor is circulated in a closed system to improve the recovery rate; after completion, the residual ethanol is purged with nitrogen at 50°C for 0.5h, and the test is repeated for 10 times, and the adsorption efficiency of the gas is tested, and the efficiency decay rate is calculated.

[0032] All performance tests are performed on Examples 1-5 and the control group, and the test results are shown in Table 1: Table 1 Performance test of Examples 1-5 From the data in the table, the modified adsorbable and regenerable high-boiling point substance molecular sieve shown in Example 3 has the best performance, and each data is improved by 150.0%, 147.1%, 158.3%, 183.3%, and 178.9% respectively compared with the commercially available molecular sieve; among them, the high-boiling point substance adsorption of Example 1 and Example 4 is better (210.3 and 234.7 mg / g), which is suitable for normal industrial waste gas environment, indicating that the tetrapropylammonium bromide+N-bromoacetamide double template system greatly improves the strength of the modified adsorbable and regenerable high-boiling point substance molecular sieve; the water drop contact angle of Example 3 is the largest (139°), and the specific surface area is the largest, indicating that its hydrophobicity is the best, and the selectivity of adsorbing high-boiling point substances is the best. The competitive adsorption decline rate is only 9%, indicating that the product molecular sieve has a wide range of applications. The decay rate of Examples 1-5 is not more than 10%; the decay rate of Example 3 is only 5.4%, indicating that the regeneration performance of wet spraying ethanol is strong, and it is more in line with the standards of large-scale industrial production.

[0033] Table 2 Performance test of Comparative Examples 1-4 and Example 1 From Table 2, the performance of each data of Comparative Examples 1-4 is weaker than that of Example 1, wherein the difference of each performance between Comparative Example 1 and Example 1 is most significant, and the difference of Comparative Examples 2-3 is less significant, mainly in specific surface area and adsorption capacity, indicating the importance of tetrapropylammonium bromide+N-bromoacetamide double template system to the adsorption capacity of modified adsorbable and renewable high-boiling-point substance molecular sieve. The selectivity of Comparative Example 4 to high-boiling-point substance is much less than before, indicating that the loading of metal Ni plays an indispensable role in selective catalysis of high-boiling-point substance; overall, the difference in hydrophobicity is not large, but overall it is better than the commercially available molecular sieve, indicating that high silica-alumina ratio plays a dominant role in hydrophobicity and overall strength.

[0034] Example 6 According to the above test results, the product obtained in Example 1 is applied in the resource treatment of high-boiling-point organic matter in industrial waste gas, including the following steps: 1) adsorption: the modified adsorbable and renewable high-boiling-point substance molecular sieve described above is filled in a fixed bed adsorption tower, and petroleum distillate containing aromatic hydrocarbons is introduced, under the condition that the temperature is 20-80℃, aromatic hydrocarbons are preferentially adsorbed, and non-aromatic hydrocarbons pass directly; 2) regeneration: under the condition that the temperature is 80-120℃, ethanol is sprayed in the form of atomization to the surface of saturated molecular sieve in a closed environment, the amount is about 1-2 mL / g of molecular sieve; in a closed system, ethanol vapor is circulated to improve the recovery rate; after completion, the residual ethanol is purged with nitrogen at 50℃ for 0.5h to avoid the decline of subsequent adsorption performance.

[0035] The above examples are only illustrative of the principles and effects of the present application, and are not intended to limit the present application. Any person skilled in the art can modify or change the above examples without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical idea disclosed by the present application should be covered by the claims of the present application.

Claims

1. A modified molecular sieve capable of adsorbing and regenerating high-boiling-point substances, characterized in that: It includes the following raw materials in parts by weight: 6.6-11 parts of NaOH; 9-11 parts of tetrapropylammonium bromide; 120-130 parts of silica sol; 3-4 parts of N-bromoacetamide; 0.1-0.3 parts of aluminum sulfate; and 175-246 parts of deionized water.

2. A method for preparing a modified molecular sieve capable of adsorbing and regenerating high-boiling-point substances, characterized in that: The following steps are involved: 1) Dissolve NaOH in deionized water. After it is completely dissolved, add tetrapropylammonium bromide and stir until the solution is clear. Finally, add silica sol and stir continuously for 1 hour to form a uniform gel solution. The prepared gel solution is aged at 30°C for 24 hours and dissolved in deionized water to obtain a guided gel. 2) Dissolve NaOH in deionized water, add silica sol after it is completely dissolved and stir evenly, reflux and stir in a constant temperature water bath at 80°C for 1 hour to obtain alkali-treated silica sol; 3) Add NaOH to deionized water. Once completely dissolved, add N-bromoacetamide and aluminum sulfate, stirring until completely dissolved. Then add the alkali-treated silica sol obtained in 2) and continue stirring until homogeneous to obtain a uniform gel. 4) adding 1.0 g of the guiding gel obtained in 1) to the uniform gel obtained in 3) at a ratio of 1.0 g of SiO2 to 100.0 mg of the guiding gel. The resulting gel solution was subjected to dynamic crystallization at 90°C for 6 hours and then to dynamic crystallization at 170°C for 24 hours. After the crystallization, the template was removed by centrifugal filtration, washing, drying, and calcination to obtain a high-silica ZSM-5 molecular sieve. 5) The molecular sieve obtained in 4) was placed in an alumina crucible in a muffle furnace and calcined at 550°C for 5 h. After cooling to room temperature, the crucible was removed and 1.460 g of Ni(NO3)2·6H2O was dissolved in deionized water to prepare a 200 mL solution by wet impregnation. 10 g of the calcined ZSM-5 was added to the solution and stirred in an 80°C water bath for 5 h to obtain a metal-modified ZSM-5 paste. The metal-modified ZSM-5 was taken out and placed in a forced air drying oven for 24 hours, and then activated and pretreated again, and then ground and sieved to obtain the final product.

3. The method for preparing the modified adsorbable regenerable high boiling point substance molecular sieve according to claim 2, characterized in that: The raw materials used in the above 1) are as follows: 0.6-1.0 parts by weight of NaOH; 35-40 parts by weight of deionized water; 9-11 parts by weight of tetrapropylammonium bromide; and 45-50 parts by weight of silica sol.

4. The method for preparing the modified adsorbable regenerable high boiling point substance molecular sieve according to claim 2, characterized in that: The raw materials used in the above 2) are as follows: 5-8 parts by weight of NaOH; 120-126 parts by weight of deionized water; and 75-85 parts by weight of silica sol.

5. The method for preparing the modified adsorbable regenerable high boiling point substance molecular sieve according to claim 2, characterized in that: The raw materials used in the above 3) are as follows: 1-2 parts of NaOH; 70-80 parts of deionized water; 3-4 parts of N-bromoacetamide; 0.1-0.3 parts of aluminum sulfate; and 100-105 parts of alkali-treated silica sol.

6. The method for preparing the modified adsorbable regenerable high boiling point substance molecular sieve according to claim 2, characterized in that: The metal loading in the above 5) is 3% of the mass of the high-silicon ZSM-5 molecular sieve.

7. The method for preparing the modified adsorbable regenerable high boiling point substance molecular sieve according to claim 2, characterized in that: The activation pretreatment in 5) is a calcination operation at a temperature of about 500° C. for 5 hours.

8. The use of the modified adsorbable regenerable high boiling point substance molecular sieve according to claim 1 in chemical production, characterized in that: The following steps are involved: 1) Adsorption: The modified adsorbable regenerable high-boiling point substance molecular sieve according to claim 1 is filled in a fixed-bed adsorption tower, and a petroleum fraction containing aromatic hydrocarbons is introduced. At a temperature of 20-80°C, aromatic hydrocarbons are preferentially adsorbed, while non-aromatic hydrocarbons pass directly through. 2) Regeneration: At a temperature of 80-120°C, in a closed environment, spray ethanol in atomized form onto the surface of the saturated molecular sieve at a rate of approximately 1-2 mL / g of molecular sieve; circulate ethanol vapor in a closed system to improve the recovery rate; after completion, purge the residual ethanol with nitrogen at 50°C for 0.5 h to avoid subsequent degradation of adsorption performance.

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