COP-coated SiO2 solid-phase adsorbent based on oil dearomatization, solid-phase extraction column based on COP-coated SiO2 solid-phase adsorbent, and preparation method and application of COP-coated SiO2 solid-phase adsorbent

Abstract

The invention discloses a COP-coated SiO2 solid-phase adsorbent based on dearomatization of an oil product, a solid-phase extraction column based on the COP-coated SiO2 solid-phase adsorbent and a preparation method and application of the COP-coated SiO2 solid-phase adsorbent, belongs to the technical field of adsorption separation and is used for enriching and separating aromatic hydrocarbons in the oil product. According to the solid-phase adsorbent, 1, 3, 5-trimesoyl chloride is used as a node, biphenyl is used as a linker, an aromatic covalent organic polymer (COP) is fixed on the surface of silicon dioxide through a Friedel-Crafts reaction, and the COP-coated SiO2 solid-phase adsorbent is obtained. According to the COP-coated SiO2 solid-phase adsorbent, the organic polymer is bonded to the surface of silicon dioxide, so that the density of an aryl ligand in a stationary phase can be effectively improved, the aromatic selectivity of the solid-phase adsorbent is improved, and the adsorption efficiency of the solid-phase adsorbent is improved. The technical problem of poor adsorption efficiency caused by low bonding density of a solid-phase adsorbent in the prior art is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of adsorption separation, and specifically relates to a COP@SiO2 solid phase adsorbent based on oil dearomatization, a solid phase extraction column based thereon, and a preparation method and application thereof. Background Art

[0002] Dearomatization of oil products will not only improve the quality and performance of oil products, but also have significant environmental benefits and promote the transformation and upgrading of the oil refining industry. Excessive aromatic content in oil products will lead to a decrease in its cetane number, poor storage stability, and easy generation of carbon deposits and carbon smoke during combustion, which will affect the performance of oil products. Through dearomatization treatment, the aromatic content in oil products can be effectively reduced, its cetane number and storage stability can be improved, and the generation of combustion carbon deposits and carbon smoke can be reduced, thereby improving the quality and performance of oil products. Polycyclic aromatic hydrocarbons (PAHs) are very harmful to the environment and human health. Through dearomatization treatment, the PAHs content in oil products can be significantly reduced, reducing its pollution to the environment and harm to the human body. For example, the application of environmentally friendly solvents such as light white oil and isoparaffins can replace traditional aromatic solvents and reduce pollution to the environment. In the oil refining industry, the application of dearomatization technology can promote industrial transformation and upgrading. For example, green and efficient aromatic adsorption separation technology uses physical means to efficiently separate aromatic and non-aromatic components in oil products, converting them into chemical raw materials that are in short supply in the market, achieving differentiated, high-value and refined utilization of oil products, and promoting the transformation, upgrading and high-quality development of the traditional refining industry.

[0003] The traditional hydrodearomatization process has the problems of high equipment investment and harsh operating conditions. In contrast, the use of solid phase extraction for dearomatization has the advantages of high aromatic selectivity, mild operating conditions, simple technology, low investment and operating costs. Solid phase extraction enrichment technology has become a powerful tool for separating and concentrating trace analytical substances due to its characteristics of low solvent usage, simple operation, high selectivity, good reproducibility and strong anti-interference ability. The key to solid phase extraction lies in the selection of adsorbents. Generally, porous materials with large specific surface area and stable chemical properties are selected. The current research and development of highly selective adsorbents mainly introduces groups with selective adsorption or chelation functions on the surface of solid matrices. Common solid matrices include fibers, resins, activated carbon, inorganic oxides, etc. Among them, silica gel has the characteristics of strong acid resistance, no swelling, high temperature resistance, and good mechanical stability, and is the most widely used inorganic carrier.

[0004] The modification of traditional adsorbents is to introduce functional groups with selective adsorption into the parent body to achieve selective enrichment and separation of single or multiple components. Chinese patent CN118320791A discloses a SiO2 solid phase extraction filler modified with anthracene polyarylether dendritic small molecule gel factor and its preparation method. The solid phase extraction filler is silica modified with anthracene polyarylether dendritic small molecule gel factor. Although the adsorbent improves the adsorption capacity and molecular shape selectivity of the solid phase extraction filler for organic matter, the adsorbent has low bonding density and poor adsorption efficiency. Summary of the invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a COP@SiO2 solid-phase adsorbent based on oil dearomatization, and a solid-phase extraction column based thereon, and a preparation method and application thereof, so as to solve the technical problems of low bonding density and poor adsorption efficiency of solid-phase adsorbents for oil dearomatization in the prior art.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The present invention provides a COP@SiO2 solid phase adsorbent based on oil dearomaticization, comprising bonding an aromatic covalent organic polymer COP to the surface of silica to obtain a COP@SiO2 solid phase adsorbent, wherein the structural formula of the aromatic covalent organic polymer COP is: .

[0007] The present invention also provides a method for preparing the above-mentioned COP@SiO2 solid phase adsorbent based on oil dearomaticization, comprising mixing phenyl silica gel and a solvent, ultrasonically treating for 2-10 min to obtain a suspension, adding biphenyl and 1,3,5-triphenylethylene chloride to the suspension in a nitrogen atmosphere, mixing and stirring, and adding a catalyst to obtain the COP@SiO2 solid phase adsorbent.

[0008] More preferably, the catalyst is anhydrous aluminum chloride.

[0009] Anhydrous aluminum chloride plays the role of Lewis acid in this process, which can coordinate with halogen to generate electrophilic reagents, thereby promoting the reaction and improving the adsorption efficiency of the solid phase adsorbent.

[0010] Preferably, the dosage ratio of phenyl silica gel, solvent, biphenyl, 1,3,5-triphenylethylene chloride, suspension and catalyst is (1-10) g: (30-300) ml: (0.1-1) g: (0.2-2) g: (40-408) g: (0.5-3) g. Preferably, after adding the catalyst, the reaction temperature is maintained at 25-30° C. and the reaction time is 12-48 h.

[0011] Preferably, after adding the catalyst, the mixture is filtered and Soxhlet extracted for 6-24 h.

[0012] Preferably, the solvent in the Soxhlet extraction is prepared using water and dichloromethane, and the volume ratio of water to dichloromethane is 1:5.

[0013] The present invention also provides a solid phase extraction column prepared by using the above COP@SiO2 solid phase adsorbent based on oil dearomatization.

[0014] Further preferably, the solid phase extraction column comprises a column body, wherein the column body comprises a hollow cavity and an upper sieve plate and a lower sieve plate disposed in the hollow cavity, and a COP@SiO2 solid phase adsorbent is filled between the upper sieve plate and the lower sieve plate.

[0015] By designing the column structure and filling method of the solid phase adsorbent between the upper and lower sieve plates, the adsorbent can be evenly distributed and work stably in the column, thereby improving the extraction efficiency and accuracy. The column provides the necessary space and support, while the sieve plate ensures that the extractant can be evenly distributed and remain stable. The extractant is filled between the sieve plates and is responsible for adsorbing and separating the target compounds.

[0016] Further preferably, the preparation method of the above-mentioned solid phase extraction column comprises the following steps: placing a nylon membrane and a 10 μm filter membrane (lower sieve plate) horizontally at the bottom of the solid phase extraction column in sequence, using an electronic balance to weigh 10-50 mg of dry COP@SiO2 powder and fill it into the solid phase extraction column, then adding an appropriate amount of anhydrous ethanol and stirring evenly, standing and waiting for ethanol to flow out, repeating this process until the surface of the COP@SiO2 powder in the solid phase extraction column is flat, and then placing a 10 μm filter membrane (upper sieve plate), pressing the upper filter membrane with a syringe, and compacting the COP@SiO2 powder therein until it cannot be pressed. The filled solid phase extraction column COP@SiO2-SPE column is stored in anhydrous ethanol.

[0017] By placing nylon membrane and filter membrane, it plays the role of supporting and protecting the adsorbent to prevent it from being lost or damaged during operation.

[0018] Further preferably, the filling mass of COP@SiO2 solid phase adsorbent powder is 20 mg.

[0019] More preferably, the stirring time is 1 min.

[0020] The present invention also provides a method for solid phase extraction of aromatic compounds in oil products using the above solid phase extraction column, comprising the following steps: Activate the solid phase extraction column; Activation can not only remove interfering substances that may exist in the adsorbent, but also improve the recovery efficiency of the target product; Inject the oil product into the activated solid phase extraction column; The activated solid phase extraction column is eluted, and the eluent comprises a combination of one or more of acetone, ethyl acetate and n-hexane; The washed solid phase extraction column is eluted, and the eluent includes a combination of one or more of acetone, methanol, dichloromethane, ethanol, ethyl acetate and n-hexane.

[0021] Preferably, the eluent comprises dichloromethane and ethanol in a volume ratio of 5:1.

[0022] More preferably, n-hexane is used to activate the solid phase extraction column.

[0023] The present invention also provides the use of the COP@SiO2 solid phase adsorbent in enriching and separating aromatic compounds in oil products, wherein the aromatic compounds include benzene, naphthalene, acenaphthene, fluorene, phenanthrene or anthracene.

[0024] Generally speaking, the smaller the extraction pressure, the more conducive it is to the full contact between the adsorbent and PAHs. However, a decrease in extraction pressure also means an increase in extraction time. Moreover, when the extraction pressure is reduced to a certain value, the sample may not even be able to pass through the solid phase extraction column.

[0025] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a COP@SiO2 solid phase adsorbent based on oil dearomaticization. It can be seen from the structural formula of the aromatic covalent organic polymer COP that the molecular weight of the covalent organic polymer (COP) is very high. The aromatic covalent organic polymer COP is bonded to the surface of silica, so that the surface of the COP@SiO2 solid phase adsorbent has a high density of aromatic ligands, enriching the content of aromatic ligands on the aromatic phase surface, thereby improving the characteristics of the COP@SiO2 solid phase adsorbent in terms of aromatic selectivity, thereby promoting the adsorption efficiency of the solid phase adsorbent.

[0026] The present invention also provides a method for preparing the above-mentioned COP@SiO2 solid phase adsorbent based on oil dearomaticization, which uses silicon dioxide as a matrix and 1,3,5-triphenylamine chloride as a node. 1,3,5-triphenylamine chloride has three acyl chloride groups with high reaction activity, which can undergo condensation reaction with biphenyl. Biphenyl is used as a linker, and the benzene rings at both ends can react with the acyl chloride groups of 1,3,5-triphenylamine chloride to form covalent bonds, thereby constructing the structure of COP, and then the aromatic COP is fixed on the surface of silicon dioxide by Friedel-Crafts reaction under the catalysis of a catalyst to prepare COP@SiO2 solid phase adsorbent. Covalent organic polymers, as a new type of porous material, have a large specific surface area and porous structure, and good thermal stability. They have great potential as ideal adsorbents for solid phase extraction pretreatment and enrichment of organic compounds. In view of the fact that covalent organic polymers contain abundant aromatic rings, the polymers are used to modify silica, which increases the density of aromatic ligands on the surface of COP@SiO2 solid phase adsorbent, thereby improving the aromatic selectivity of COP@SiO2 solid phase adsorbent and promoting the adsorption efficiency of COP@SiO2 solid phase adsorbent.

[0027] Furthermore, the dosage ratio of phenyl silica gel, solvent, biphenyl, 1,3,5-benzene trimesoyl chloride, suspension and catalyst was clarified, which helps to ensure the uniform mixing of the components in the reaction system, thereby improving the reaction efficiency and the quality of the adsorbent. At the same time, it helps to improve the structural stability and adsorption performance of the adsorbent. Furthermore, a temperature range of 25 to 30° C. and a reaction time of 12-48 h are favorable for the reaction and avoid side reactions and polymer degradation caused by high temperature.

[0028] Furthermore, Soxhlet extraction using a solvent prepared with water and dichloromethane can thoroughly wash away the remaining catalyst (anhydrous aluminum chloride) and residual polymer, ensuring the purity and performance of the adsorbent.

[0029] The present invention also provides a solid phase extraction column prepared by using the solid phase adsorbent, which has excellent extraction performance and improves the extraction efficiency.

[0030] The present invention also provides a method for solid phase extraction of aromatic compounds in oil products using the above-mentioned solid phase extraction column, selecting a washing liquid including any one or more of acetone, ethyl acetate or n-hexane and an eluent including any one or more of acetone, methanol, dichloromethane, ethanol, ethyl acetate or n-hexane, thereby effectively improving the extraction efficiency of the solid phase extraction column.

[0031] The present invention also provides an application of the COP@SiO2 solid phase adsorbent in enriching and separating aromatic compounds in oil products. Experimental verification shows that the solid phase adsorbent has a high adsorption efficiency when adsorbing aromatic compounds such as benzene, naphthalene, acenaphthene, fluorene, phenanthrene or anthracene, and can be reused. Dearomatization of oil products is not only of great significance in terms of performance improvement, environmental protection and economic benefits, but also meets the needs of specific applications such as fine chemicals. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is the reaction formula of the solid phase adsorbent of the present invention; Figure 2 It is a schematic diagram of the structure of the solid phase extraction column of the present invention; Figure 3 It is a schematic diagram of the solid phase extraction process of the present invention; Figure 4 is the infrared spectrum of the solid phase adsorbent of the present invention; Figure 5 This is a schematic diagram of the repeatability verification of the solid phase extraction of the present invention; Among them, 1-column; 2-upper sieve plate; 3-lower sieve plate; 4-column head. DETAILED DESCRIPTION

[0033] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0034] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0035] Herein, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible sub-ranges and individual values ​​within the range.

[0036] In this document, unless otherwise specified, “includes,” “including,” “contains,” “has,” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0037] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0038] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0039] The following examples use conventional instruments and equipment in the art. The experimental methods in the following examples where specific conditions are not specified are usually carried out under conventional conditions or under conditions recommended by the manufacturer. The various raw materials used in the following examples are conventional commercial products unless otherwise specified, and their specifications are conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" means weight percentage, "part" means weight part, and ratio means weight ratio.

[0040] The invention discloses a COP@SiO2 solid phase adsorbent based on oil dearomaticization, wherein the solid phase adsorbent uses 1,3,5-triphenylamine chloride as a node and biphenyl as a linker, and fixes an aromatic covalent organic polymer (COP) on the surface of silica through a Friedel-Crafts reaction to obtain the COP@SiO2 solid phase adsorbent, and then the product is uniformly filled in a solid phase extraction column to obtain a solid phase extraction column. The COP@SiO2 solid phase adsorbent bonds the organic polymer to the surface of silica, which can effectively increase the density of aromatic ligands in the stationary phase, thereby improving the characteristics of the stationary phase in terms of aromatic selectivity.

[0041] The present application discloses a method for preparing the above-mentioned COP@SiO2 solid phase adsorbent based on dearomatization of oil products, including fixing aromatic COP on the surface of silica by Friedel-Crafts reaction under the catalysis of anhydrous aluminum chloride using 1,3,5-benzene trimesoyl chloride as a node and biphenyl as a linker, to obtain COP@SiO2 solid phase adsorbent. The designed COP@SiO2 solid phase adsorbent can be used to recycle aromatic byproducts in oil products and increase economic benefits. At the same time, by improving the quality of oil products, the market competitiveness of products can be further enhanced.

[0042] Use Figure 1 The reaction formula shown in the present application is as follows: Add 1-10 g of phenyl silica gel to a three-necked flask containing 30-300 ml of dry dichloromethane and ultrasonically treat for 2-10 min. Add 0.1-1 g of biphenyl and 0.2-2 g of 1,3,5-benzene trimesoyl chloride to the above suspension in a nitrogen atmosphere and keep stirring. Subsequently, slowly add 0.5-3 g of anhydrous aluminum chloride. Keep the reaction at 25-30°C for 12-48 hours. After the reaction is completed, filter with a sand core funnel and perform Soxhlet extraction with water and dichloromethane as solvents for 6-24 hours to fully wash the remaining catalyst and residual polymer.

[0043] Friedel-Crafts reaction mechanism: 1. Electrophilic substitution: Under the catalysis of anhydrous aluminum chloride, the acyl chloride group of 1,3,5-triphenylethylene chloride is activated as an electrophilic reagent, and the hydrogen atoms on the benzene ring of biphenyl are replaced by the electrophilic reagent to form a carbon cation intermediate.

[0044] 2. Condensation reaction: The formed carbon cation intermediate undergoes a condensation reaction with the acyl chloride group of another 1,3,5-trimethylbenzene chloride molecule, removing hydrogen chloride to form a covalent bond. Through multiple such condensation reactions, biphenyl and 1,3,5-trimethylbenzene chloride are connected to form a high molecular weight COP.

[0045] 3. Immobilization: During the reaction, COP combines with the hydroxyl groups or other active groups on the surface of phenyl silica gel through chemical bonds, thereby achieving the immobilization of COP on the surface of silica.

[0046] The present application also discloses a solid phase extraction column prepared by using the above-mentioned COP@SiO2 solid phase adsorbent based on oil dearomatization, comprising: The invention comprises a column 1, which comprises a hollow cavity and an upper sieve plate 2 and a lower sieve plate 3 arranged in the hollow cavity, a solid phase adsorbent is filled between the upper sieve plate 2 and the lower sieve plate 3, and a column head 4 is connected below the column 1 for eluting and collecting the target.

[0047] The present application also discloses a method for solid phase extraction using the above solid phase extraction column: It includes four steps: activation, loading, elution and washing of the SPE column. First, the SPE column is activated, which can not only remove the interfering substances that may exist in the adsorbent, but also improve the recovery efficiency of the target. After activation, the actual sample passes through the SPE column. In this step, the target and some impurities are adsorbed on the solid phase components. After that, the target is eluted and collected. The eluent must be strong enough to elute the target with the minimum amount and meet the requirements for selectivity. Only the target is eluted as much as possible, while impurities with strong adsorption are still retained on the SPE column.

[0048] The specific implementation steps are as follows: activate the solid phase extraction column with n-hexane before use, control the vacuum pump to make the pressure in the solid phase extraction device reach 0.01-0.06MPa, pass the oil through the solid phase extraction column several times, and after all samples have passed through the column, add eluent to elute the column, place the column on the solid phase extraction device, set a certain pressure, add eluent to the column several times, collect the liquid passing through the solid phase extraction column, and collect it in the injection bottle for testing.

[0049] Preferably, the eluent is any one or more of acetone, ethyl acetate and n-hexane.

[0050] More preferably, the eluent is n-hexane.

[0051] Preferably, the eluent is any one or more of acetone, methanol, dichloromethane, ethanol, ethyl acetate and n-hexane.

[0052] More preferably, the eluent is a combination of dichloromethane and ethanol, and the volume ratio of the two is 5:1.

[0053] Further preferably, the small column is placed on a solid phase extraction device, and the extraction pressure is set to 0.01 MPa-0.08 MPa, and optionally, 0.02 MPa is used as the optimal extraction pressure.

[0054] Solid phase extraction process Figure 2 As shown in the figure, the sample passes through the extraction column filled with adsorbent material. Since the solid phase adsorbent has a greater adsorption capacity for the target analyte than the liquid phase component, most of the target and some impurities will be adsorbed on the solid phase adsorbent. The other components in the sample pass through the solid phase extraction column. At this time, an appropriate organic solvent is selected to elute the target from the adsorbent, thereby achieving the purpose of separating the target from the sample matrix and enriching the target.

[0055] The technical solution of the present application is further described below in conjunction with specific embodiments and drawings.

[0056] Example 1 like Figure 1 As shown, 1.20 g of phenyl silica gel was added to a three-necked flask containing 30 mL of dry dichloromethane and ultrasonically treated for 5 min. 0.1 g of biphenyl and 0.2 g of 1,3,5-benzene trimesoyl chloride were added to the above suspension in a nitrogen atmosphere and kept stirring. Subsequently, 0.5 g of anhydrous aluminum chloride was slowly added to 40 g of the suspension. The reaction was maintained at 30 ° C for 24 h. After the reaction was completed, it was filtered using a sand core funnel and Soxhlet extraction was performed with solvents prepared with water and dichloromethane for 12 h to obtain COP@SiO2 solid phase adsorbent.

[0057] like Figure 4 As shown, the COP@SiO2 solid phase adsorbent prepared in Example 1 was tested and analyzed. In the FT-IR spectrum of COP@SiO2, 1657 cm -1 The absorption peak at 1728 cm -1 The characteristic absorption at is generated by the C=O stretching vibration in the skeleton, which is a sign of the successful reaction between the acyl chloride group and biphenyl, indicating that COP is successfully fixed to the silica surface. After testing, the specific surface area of ​​COP is 298m 2 ·g -1 , pore volume 0.672cm 3 ·g -1 , indicating that the covalent organic polymer (COP) prepared by this method has a large specific surface area and porous structure, thus providing more space for the solid phase adsorbent surface to accommodate high-density aromatic ligands.

[0058] Example 2 5 g of phenyl silica gel was added to a three-necked flask containing 165 mL of dry dichloromethane and ultrasonically treated for 2 min. 0.55 g of biphenyl and 1.1 g of 1,3,5-triphenylamine chloride were added to the above suspension in a nitrogen atmosphere and stirred. Subsequently, 1.02 g of anhydrous aluminum chloride was slowly added to the 224 g suspension. The reaction was maintained at 25 ° C for 30 h. After the reaction was completed, the mixture was filtered using a sand core funnel and Soxhlet extraction was performed with solvents prepared with water and dichloromethane for 12 h to obtain COP@SiO2 solid phase adsorbent.

[0059] Example 3 10 g of phenyl silica gel was added to a three-necked flask containing 300 mL of dry dichloromethane and ultrasonically treated for 6 min. 1 g of biphenyl and 2 g of 1,3,5-benzene trimesoyl chloride were added to the above suspension in a nitrogen atmosphere and stirred. Subsequently, 3 g of anhydrous aluminum chloride was slowly added to 408 g of the suspension. The reaction was maintained at 27 ° C for 48 h. After the reaction was completed, the mixture was filtered using a sand core funnel and Soxhlet extraction was performed with solvents prepared with water and dichloromethane for 12 h to obtain COP@SiO2 solid phase adsorbent.

[0060] Example 4 The solid phase adsorbent in Example 1 is used to prepare a solid phase extraction column, comprising the following steps: like Figure 2As shown, a nylon membrane and a 10 μm filter membrane (lower sieve plate) are placed horizontally at the bottom of the column 1 in sequence, and 20 mg of dry COP@SiO2 solid phase adsorbent powder is weighed using an electronic balance and filled into the column 1. Then, an appropriate amount of anhydrous ethanol is added, stirred evenly, and then allowed to stand for the ethanol to flow out. This process is repeated until the surface of the COP@SiO2 powder in the column 1 is flat, and then a 10 μm filter membrane (upper sieve plate) is placed, and the upper filter membrane is pressed down with a syringe to compact the COP@SiO2 powder therein until it cannot be pressed. The filled solid phase extraction column COP@SiO2-SPE column is stored in anhydrous ethanol to prevent it from drying.

[0061] like Figure 3 As shown, a method for solid phase extraction of aromatic compounds in oil products using the solid phase extraction column prepared as above is as follows: The solid phase extraction column was activated with 0.5 mL of n-hexane, and the vacuum pump was controlled to keep the pressure in the solid phase extraction device at 0.1 MPa. 20 mL of laboratory oil was passed through the solid phase extraction column for 1 to 5 minutes. After all samples passed through the small column, 2 mL of n-hexane was added to elute the solid phase extraction column, and the eluent was collected. The solid phase extraction column was then placed on the solid phase extraction device, the pressure was set to 0.02 MPa, 2 mL of eluent was added to the solid phase extraction column several times, and the liquid passing through the solid phase extraction column was collected; the eluent was prepared from dichloromethane and ethanol, and the volume ratio of dichloromethane to ethanol was 5:1.

[0062] Example 5 The difference between this embodiment and embodiment 4 is that in the method for preparing the solid phase extraction column, 10 mg of COP@SiO2 solid phase adsorbent powder is weighed, and in the method for performing solid phase extraction using the solid phase extraction column prepared in this embodiment, ethyl acetate is used as the eluent and acetone is used as the eluent, and the other conditions are the same.

[0063] Example 6 The difference between this embodiment and embodiment 4 is that in the method for preparing the solid phase extraction column, 50 mg of COP@SiO2 solid phase adsorbent powder is weighed, and in the method for performing solid phase extraction using the solid phase extraction column prepared in this embodiment, ethyl acetate is used as the eluent and acetone is used as the eluent, and the other conditions are the same.

[0064] Calculation process of aromatic content: The detection of aromatic hydrocarbon content is based on NB / SH / T 0966-2017 Determination of aromatic hydrocarbon content in white oil by ultraviolet spectrophotometry. The undiluted or isooctane-diluted white oil sample is placed in a quartz cuvette, and the maximum absorbance near 270nm, the absorbance at 285.0nm and the baseline absorbance are measured on a UV-visible spectrophotometer. The content of alkylbenzene and naphthalene compounds is calculated using the known average absorption coefficient, and the sum of the contents of alkylbenzene and naphthalene compounds is taken as the aromatic hydrocarbon content of the sample.

[0065] Mass fraction of naphthalene compounds W N % is calculated according to formula (1): W N = (1) Where: 100—factor for conversion to mass fraction; —Absorbance value above the baseline at a wavelength of 285.0 nm (the difference between the absorbance at a wavelength of 285.0 nm and the absorbance at the baseline); 33.7—average absorption coefficient of naphthalene compounds, in liters per gram per centimeter (L / (g·cm)); B—optical path of the cuvette, in centimeters (cm); D—density of undiluted sample or concentration of diluted sample, in grams per liter (g / L). Mass fraction of alkylbenzene compounds W B % is calculated according to formula (2): W B = (2) Where: —The maximum absorbance above the baseline near 270nm (the difference between the maximum absorbance near the wavelength of 270nm and the baseline absorbance); 0.89—constant, the ratio of the absorption coefficients of naphthalene at 270nm and 285nm (30.0 / 33.7); 3.01—average absorption coefficient of alkylbenzene compounds, in liters per gram per centimeter (L / (g·cm)); The mass fraction W% of aromatics in the sample is calculated according to formula (3): W=W B +W N (3) Where: W N —Naphthalene compound content (mass fraction), %; W B —Content of alkylbenzene compounds (mass fraction), %; According to the above calculation method, the aromatic content in the laboratory oil, eluent and elution was measured and calculated, and the results are shown in Table 1 below: Table 1:

[0066] In order to investigate the reusability of the material, the COP@SiO2 solid phase extraction column prepared in Example 4 was used to repeat the solid phase extraction experiment on the above oil product 1 30 times, and the aromatic hydrocarbon content of the collected solid phase extraction eluent was measured to evaluate the reusability of the solid phase extraction column.

[0067] The results are as follows Figure 5 As shown, the recovery rate of the eluent of oil product 1 did not change significantly after the solid phase extraction experiment, indicating that the prepared solid phase extraction column has good adsorption capacity and stable performance, and the material can be reused, which is suitable for large-scale application in the field of solid phase extraction.

[0068] Configuration method of simulated oil: The elution ability of the eluent was investigated using a self-prepared simulated oil (benzene + naphthalene + acenaphthene + fluorene + phenanthrene + anthracene + cyclohexane system). 0.5 g of aromatic hydrocarbons were dissolved in 10 g of cyclohexane, and ultrasonic vibration was used for 15 min to fully dissolve the aromatic hydrocarbons in cyclohexane and store them in a sealed state at low temperature.

[0069] Agilent 8890 gas chromatograph was used to determine the aromatic content in the simulated oil and eluent. The gas phase conditions were as follows: helium as carrier gas, velocity 36.623 cm / s, constant flow mode; injection in splitless mode, and transfer line temperature 280 °C. The gradient program was initially 60 °C (held for 1 min), then raised to 170 °C at 40 °C / min, and then raised to 310 °C at 10 °C / min (held for 3 min). The liquid to be tested entered the gas chromatograph for analysis, and the recovery rates of the six analytes (benzene, naphthalene, acenaphthene, fluorene, phenanthrene and anthracene) were measured to be in the range of 85%-110%.

[0070] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A COP@SiO2 solid phase adsorbent based on oil dearomaticization, characterized in that: The method comprises bonding an aromatic covalent organic polymer COP to the surface of silicon dioxide to obtain a COP@SiO2 solid phase adsorbent, wherein the aromatic covalent organic polymer COP has the structural formula: 。 2. The method for preparing the COP@SiO2 solid phase adsorbent based on oil dearomatization according to claim 1, characterized in that: Phenyl silica gel and a solvent are mixed and ultrasonically treated to obtain a suspension. Biphenyl and 1,3,5-triphenylethylene chloride are added to the suspension in a nitrogen atmosphere and mixed and stirred. A catalyst is added to obtain a COP@SiO2 solid phase adsorbent.

3. The method for preparing the COP@SiO2 solid phase adsorbent based on oil dearomatization according to claim 2, characterized in that: The dosage ratio of phenyl silica gel, solvent, biphenyl, 1,3,5-triphenylethylene chloride, suspension and catalyst is (1-10) g: (30-300) ml: (0.1-1) g: (0.2-2) g: (40-408) g: (0.5-3) g.

4. The method for preparing the COP@SiO2 solid phase adsorbent based on oil dearomatization according to claim 2, characterized in that: After adding the catalyst, the reaction temperature is maintained at 25-30°C and the reaction time is 12-48 h.

5. The method for preparing the COP@SiO2 solid phase adsorbent based on oil dearomatization according to claim 2, characterized in that: After adding the catalyst, the mixture was filtered and Soxhlet extracted for 6-24 h.

6. The method for preparing the COP@SiO2 solid phase adsorbent based on oil dearomatization according to claim 5, characterized in that: The solvent in the Soxhlet extraction is prepared using water and dichloromethane, and the volume ratio of water to dichloromethane is 1:

5.

7. A solid phase extraction column prepared using the COP@SiO2 solid phase adsorbent based on oil dearomatization as claimed in claim 1.

8. A method for solid phase extraction of aromatic compounds in oil products using the solid phase extraction column according to claim 7, characterized in that: The steps include: Activating the solid phase extraction column; Inject the oil product into the activated solid phase extraction column; The activated solid phase extraction column is eluted, and the eluent comprises a combination of one or more of acetone, ethyl acetate and n-hexane; The washed solid phase extraction column is eluted, and the eluent includes a combination of one or more of acetone, methanol, dichloromethane, ethanol, ethyl acetate and n-hexane.

9. The method for solid phase extraction according to claim 8, characterized in that: The eluent includes dichloromethane and ethanol in a volume ratio of 5:

1.

10. The use of the COP@SiO2 solid phase adsorbent according to claim 1 in enriching and separating aromatic compounds in oil products, characterized in that: Aromatic hydrocarbon compounds include benzene, naphthalene, acenaphthene, fluorene, phenanthrene or anthracene.

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