A Hydrophilic Hydrocarbon-Modified ZSM-5 Molecular Sieve Adsorbent, Its Preparation Method and Application

Abstract

The present invention discloses a surface hydrocarbonophilic modified ZSM-5 molecular sieve adsorbent, its preparation method and application, belonging to the technical field of inorganic nanomaterial preparation; in the present invention, a medium-temperature coal tar pitch extraction liquid is used as a surface hydrocarbonophilic modification liquid, and is mixed with ZSM-5 molecular sieves with different silicon-aluminum ratios according to a certain mass ratio for impregnation treatment, and then filtered and dried to obtain a surface hydrocarbonophilic modified ZSM-5 molecular sieve adsorbent; the ZSM-5 adsorbent prepared by the present invention has the characteristics of high CH4 adsorption capacity, high CH4 / N2 selectivity and high stability. The process only involves the impregnation of primary raw materials, greatly simplifies the operation compared with the traditional ion exchange modification strategy and has a wider application range, and is suitable for the concentration of ventilation air methane.

Description

Technical Field

[0001] The present invention belongs to the technical field of inorganic nanomaterial preparation, and specifically relates to a surface hydrocarbonophilic modified ZSM-5 molecular sieve adsorbent, its preparation method and application. This adsorbent can be used for the concentration of ventilation air methane (VAM). Background Art

[0002] The maximum pore diameter of ZSM-5 molecular sieve is 6.36 Å, and the maximum diffusion diameter is 4.70 Å. Due to its suitable pore structure and high specific surface area, it has received extensive attention in the adsorption field. Since the surface of ZSM-5 molecular sieve is highly polarized and easy to adsorb polar molecules, while CH4 is a non-polar molecule with a regular tetrahedron structure. Therefore, in order to improve the CH4 adsorption capacity, the key to modifying ZSM-5 molecular sieve lies in reducing the framework polarity and making it show hydrocarbonophilic properties.

[0003] Ion exchange modification is a conventional modification strategy for molecular sieves and has received extensive attention in the adsorption field. For example, silver ion exchange (CN117884092A), ammonium ion exchange (CN103359760A), and rare earth ion exchange (CN113522207A) etc. have achieved remarkable effects in the modification of molecular sieves with low silica-alumina ratio. However, the ion exchange modification strategy has complex operations, low exchange rate and narrow application scope, which limits its application.

[0004] Coal tar pitch is the residue after extracting light components from coal tar, which is divided into low-temperature coal tar pitch, medium-temperature coal tar pitch and high-temperature coal tar pitch, accounting for about 50% - 60% of tar. Its basic structural unit is polycyclic aromatic hydrocarbons and their derivatives, which are mainly applied in the fields of road construction, building materials, electrode manufacturing, carbon products, anticorrosive coatings and fuels, etc. Among them, medium-temperature coal tar pitch has the advantages of high carbon content, good fluidity and easy graphitization, etc. However, the complexity of its composition determines that component separation and other pretreatment are required when applying coal tar pitch. According to the principle of similar solubility, the components of coal tar pitch are enriched to obtain components with a narrower molecular weight distribution. After extraction, operations such as distillation separation, oxidation, and thermal polymerization are often required to achieve the enrichment of products, and the post-treatment operation procedures are complex. Summary of the Invention

[0005] The present invention overcomes the deficiencies of the prior art and provides a surface hydrocarbonophilic modified ZSM-5 molecular sieve adsorbent, its preparation method and application; it solves the problems of complex operations, low exchange rate and narrow application scope of molecular sieve ion exchange modification.

[0006] The present invention is realized by the following technical solutions:

[0007] A preparation method of a surface hydrocarbonophilic modified ZSM-5 molecular sieve adsorbent, comprising the following steps:

[0008] S1. Use an organic extractant to extract medium-temperature coal tar pitch, and the obtained extract is used as a surface hydrocarbonophilic modification liquid.

[0009] S2. Mix and impregnate ZSM-5 zeolite with the surface hydrocarbonophilic modification liquid at room temperature, and then obtain a surface hydrocarbonophilic modified ZSM-5 zeolite adsorbent through filtration and drying; the mass ratio of ZSM-5 zeolite to the surface hydrocarbonophilic modification liquid is 1:1 to 1:10, and the impregnation time is 12 to 48 h; the silica-alumina ratio of the ZSM-5 zeolite, that is, the molar ratio of SiO2 to Al2O3, is 25 to 100.

[0010] Preferably, the organic extractant is one or any combination of n-butanol, tetrahydrofuran, toluene, n-heptane, and quinoline.

[0011] Preferably, the mass ratio of medium-temperature coal tar pitch to the organic extractant is 1:5.

[0012] Preferably, the extraction is carried out by putting medium-temperature coal tar pitch into the organic extractant and stirring.

[0013] Preferably, the temperature of the extraction is 50 - 70 o °C, the stirring speed is 350 - 450 r / min, and the stirring time is 2 - 3 h.

[0014] Preferably, after extraction, suction filtration is carried out to obtain the extract.

[0015] Preferably, the drying is carried out in an oven at 40 - 80 o °C for 12 - 48 h.

[0016] A surface hydrocarbonophilic modified ZSM-5 zeolite adsorbent is prepared by using the preparation method of the surface hydrocarbonophilic modified ZSM-5 zeolite adsorbent described above.

[0017] The surface hydrocarbonophilic modified ZSM-5 zeolite adsorbent described above is used for enrichment of exhausted mine gas.

[0018] The beneficial effects of the present invention compared with the prior art are as follows:

[0019] After extracting medium-temperature coal tar pitch, the present invention directly uses the extract of medium-temperature coal tar pitch for surface hydrocarbonophilic modification of ZSM-5 zeolite, avoiding treatments such as separation and purification of the extract, and realizing the high-value "one-step" utilization of medium-temperature coal tar pitch. The present invention uses the extract of medium-temperature coal tar pitch to carry out surface hydrocarbonophilic modification on ZSM-5 zeolite, which has the characteristics of simple operation and wide application range.

[0020] Specifically:

[0021] 1. By taking advantage of the low polarity of organic substances, the polarity of the molecular sieve adsorbent framework is changed through simple impregnation, and the operation is simple;

[0022] 2. Directly utilize medium-temperature coal tar pitch for resource utilization to increase its added value;

[0023] 3. Compared with traditional ion exchange modification, the present invention has the advantages of simple operation, controllable and adjustable loading amount, and wide applicability;

[0024] 4. As an adsorbent for enriched ventilation air methane, it has a high CH4 adsorption capacity and CH4 / N2 selectivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is the XRD pattern of the unmodified ZSM-5 adsorbent in Comparative Example 1 of the present invention.

[0026] Figure 2 It is the XRD pattern of the ZSM-5 adsorbent obtained by surface hydrocarbonophilic modification in Example 2 of the present invention.

[0027] Figure 3 It is the FT-IR spectrum of the unmodified ZSM-5 adsorbent in Comparative Example 1 of the present invention.

[0028] Figure 4 It is the FT-IR spectrum of the ZSM-5 adsorbent obtained by surface hydrocarbonophilic modification in Example 2 of the present invention.

[0029] Figure 5 It is the structural formula of the substance with the highest content in the extraction liquid of coal tar extracted by different solvents in the present invention.

[0030] Figure 6 It is the SEM image of the ZSM-5 adsorbent in the present invention; among them, (a) is the unmodified ZSM-5 adsorbent in Comparative Example 1, (b) is the enlarged view of (a), (c) is the ZSM-5 adsorbent with surface hydrocarbonophilic modification in Example 2, and (d) is the enlarged view of (c). DETAILED DESCRIPTION OF THE INVENTION

[0031] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer and more understandable, the present invention will be further described in detail in combination with the embodiments and the drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. The technical solutions of the present invention will be described in detail below in combination with the embodiments and the drawings, but the protection scope is not limited by this.

[0032] Example 1

[0033] This example provides a surface hydrocarbonophilic modified ZSM-5 molecular sieve adsorbent and its preparation method; the specific steps are as follows:

[0034] S1. Using n-heptane as the extraction solvent for medium-temperature coal tar pitch, the mass ratio of medium-temperature coal tar pitch to n-heptane is 1:5. Put the medium-temperature coal tar pitch into n-heptane and stir evenly at 400 r / min for 2 h at 60 o °C, then carry out suction filtration to obtain an extraction liquid mainly composed of polycyclic aromatic hydrocarbons, with the highest content of pyrene. The suction filtration is to put the material into a filter flask lined with filter paper, connect the filter flask with a suction pump and carry out vacuum filtration operation on the material in the filter flask to separate the extraction liquid.

[0035] S2. Mix the extraction liquid with ZSM-5 zeolite with a silica-alumina ratio (molar ratio of SiO2 to Al2O3) of 25 according to a mass ratio of 1:1 and impregnate at room temperature. The impregnation time is 12 h, then filter, and then place it in an oven at 40 o °C to dry for 24 h to obtain ZSM-5 zeolite with surface hydrocarbonophilic modification. The impregnation operation is to mix and let stand the mixed extraction liquid and ZSM-5 zeolite at room temperature. In this example, the room temperature is 25 o °C.

[0036] Example 2

[0037] This example proposes a surface hydrocarbonophilic modified ZSM-5 zeolite adsorbent and its preparation method. Compared with Example 1, the silica-alumina ratio of the zeolite is changed, and the other steps are the same.

[0038] In this example, the silica-alumina ratio (molar ratio of SiO2 to Al2O3) of the ZSM-5 zeolite is 100.

[0039] Example 3

[0040] This example proposes a surface hydrocarbonophilic modified ZSM-5 zeolite adsorbent and its preparation method. Compared with Example 2, the mass ratio and drying time are changed, and the other steps are the same.

[0041] Specifically, in this example, the extraction liquid is mixed with ZSM-5 zeolite with a silica-alumina ratio of 100 according to a mass ratio of 1:10, left to stand at room temperature for 12 h, then filtered, and then placed in an oven at 40 o °C to dry for 48 h to obtain ZSM-5 zeolite with surface hydrocarbonophilic modification.

[0042] Example 4

[0043] This example proposes a surface hydrocarbonophilic modified ZSM-5 zeolite adsorbent and its preparation method. Compared with Example 2, the impregnation time is changed, and the other steps are the same.

[0044] In this example, the impregnation time is 48 h.

[0045] Example 5

[0046] This example presents a surface hydrocarbonophilic modified ZSM-5 molecular sieve adsorbent and its preparation method; compared with Example 2, this example changes the types of extraction solvents and drying parameters, while the remaining steps are the same.

[0047] Specifically, in this example, n-butanol is used as the extraction solvent for medium-temperature coal tar pitch. Under the same extraction conditions as in Example 2, an extraction liquid mainly composed of polycyclic aromatic hydrocarbons is obtained, in which the content of fluoranthene is the highest. The extraction liquid is mixed with ZSM-5 molecular sieve with a silica-alumina ratio (molar ratio of SiO2 to Al2O3) of 100 according to a mass ratio of 1:1, left to stand at room temperature for 12 h, filtered, and placed in a o 60 °C oven and dried for 12 h to obtain a surface hydrocarbonophilic modified ZSM-5 molecular sieve.

[0048] Example 6

[0049] This example presents a surface hydrocarbonophilic modified ZSM-5 molecular sieve adsorbent and its preparation method; compared with Example 2, this example changes the types of extraction solvents and drying parameters, while the remaining steps are the same.

[0050] Specifically, in this example, toluene is used as the extraction solvent for medium-temperature coal tar pitch. Under the same extraction conditions as in Example 2, an extraction liquid mainly composed of polycyclic aromatic hydrocarbons is obtained, in which the content of benzo[b]anthracene is the highest. The extraction liquid is mixed with ZSM-5 molecular sieve with a silica-alumina ratio of 100 according to a mass ratio of 1:1, left to stand at room temperature for 12 h, filtered, and placed in an o 80 °C oven and dried for 24 h to obtain a surface hydrocarbonophilic modified ZSM-5 molecular sieve.

[0051] Example 7

[0052] This example presents a surface hydrocarbonophilic modified ZSM-5 molecular sieve adsorbent and its preparation method; compared with Example 2, this example changes the types of extraction solvents and drying parameters, while the remaining steps are the same.

[0053] Specifically, in this example, tetrahydrofuran is used as the extraction solvent for medium-temperature coal tar pitch. Under the same extraction conditions as in Example 2, an extraction liquid mainly composed of polycyclic aromatic hydrocarbons is obtained, in which the content of quinoline is the highest. The extraction liquid is mixed with ZSM-5 molecular sieve with a silica-alumina ratio (molar ratio of SiO2 to Al2O3) of 100 according to a mass ratio of 1:1, left to stand at room temperature for 12 h, filtered, and placed in a o 70 °C oven and dried for 48 h to obtain a surface hydrocarbonophilic modified ZSM-5 molecular sieve.

[0054] Example 8

[0055] This example presents a surface-hydrocarbonophilic modified ZSM-5 molecular sieve adsorbent and its preparation method; compared with Example 2, this example changes the type of extraction solvent and the parameters of drying, while the remaining steps are the same.

[0056] Specifically, in this example, quinoline is used as the extraction solvent for medium-temperature coal tar pitch. Under the same extraction conditions as in Example 2, an extraction liquid mainly composed of polycyclic aromatic hydrocarbons is obtained, in which the content of 9,10-benzophenanthrene is the highest. The extraction liquid is mixed with ZSM-5 molecular sieve with a silica-alumina ratio (molar ratio of SiO2 to Al2O3) of 100 at a mass ratio of 1:1, left standing at room temperature for 12 h, filtered, and placed in an oven at 60 o °C and dried for 48 h to obtain a surface-hydrocarbonophilic modified ZSM-5 molecular sieve.

[0057] Example 9

[0058] This example presents a surface-hydrocarbonophilic modified ZSM-5 molecular sieve adsorbent and its preparation method; compared with Example 2, this example changes the type of extraction solvent and the parameters of drying, while the remaining steps are the same.

[0059] Specifically, in this example, a mixed solution of 50% n-heptane and 50% n-butanol by volume is used as the extraction solvent for medium-temperature coal tar pitch. Under the same extraction conditions as in Example 2, an extraction liquid mainly composed of polycyclic aromatic hydrocarbons is obtained. The extraction liquid is mixed with ZSM-5 molecular sieve with a silica-alumina ratio (molar ratio of SiO2 to Al2O3) of 100 at a mass ratio of 1:1, left standing at room temperature for 12 h, filtered, and placed in an oven at 60 o °C and dried for 48 h to obtain a surface-hydrocarbonophilic modified ZSM-5 molecular sieve.

[0060] Example 10

[0061] This example presents a surface-hydrocarbonophilic modified ZSM-5 molecular sieve adsorbent and its preparation method; compared with Example 2, this example changes the type of extraction solvent and the parameters of drying, while the remaining steps are the same.

[0062] Specifically, in this example, a mixed solution of 33% toluene, 33% tetrahydrofuran, and 33% quinoline by volume is used as the extraction solvent for medium-temperature coal tar pitch. Under the same extraction conditions, an extraction liquid mainly composed of polycyclic aromatic hydrocarbons is obtained. The extraction liquid is mixed with ZSM-5 molecular sieve with a silica-alumina ratio (molar ratio of SiO2 to Al2O3) of 100 at a mass ratio of 1:1, left standing at room temperature for 12 h, filtered, and placed in an oven at 70 o °C and dried for 48 h to obtain a surface-hydrocarbonophilic modified ZSM-5 molecular sieve.

[0063] Example 11

[0064] This example presents a surface hydrocarbonophilic modified ZSM-5 molecular sieve adsorbent and its preparation method; compared with Example 1, the extraction operation parameters are changed, and the remaining steps are the same.

[0065] Specifically, in this example, extraction is carried out by uniformly stirring at 450 r / min for 3 h under the condition of 50 o °C.

[0066] Example 12

[0067] This example presents a surface hydrocarbonophilic modified ZSM-5 molecular sieve adsorbent and its preparation method; compared with Example 1, the extraction operation parameters are changed, and the remaining steps are the same.

[0068] Specifically, in this example, extraction is carried out by uniformly stirring at 350 r / min for 2.5 h under the condition of 70 o °C.

[0069] Comparative Example 1

[0070] Comparative Example 1 is a ZSM-5 molecular sieve with a silica-alumina ratio (molar ratio of SiO2 to Al2O3) of 100 without surface hydrocarbonophilic modification treatment.

[0071] Comparative Example 2

[0072] A mixed solution of ethyl acetate and petroleum ether with a volume fraction of 10% is prepared into a surface hydrocarbonophilic modification liquid, and is mixed with a ZSM-5 molecular sieve with a silica-alumina ratio (molar ratio of SiO2 to Al2O3) of 100 according to a mass ratio of 1:1, left standing at room temperature for 12 h, filtered, and placed in an oven at 70 o °C for drying for 12 h to obtain a surface hydrocarbonophilic modified ZSM-5 molecular sieve.

[0073] Comparative Example 3

[0074] The ZSM-5 molecular sieve with a silica-alumina ratio (molar ratio of SiO2 to Al2O3) of 100 is leached and activated with 0.1 mol / L nitric acid solution, a silver nitrate solution with a concentration of 1 mol / L is prepared, and the activated ZSM-5 molecular sieve is added to the silver nitrate solution, and ion exchange is carried out by water bath heating at 80 o °C for 6 h, and then after centrifugation, washing, and drying, it is calcined at 550 o °C for 2 h in a nitrogen atmosphere to obtain an ion-exchanged ZSM-5 molecular sieve.

[0075] XRD tests were carried out on the samples obtained in Comparative Example 1 and Example 2 ( Figure 1 and Figure 2), By comparing the two figures, it is found that the intensity of the crystal diffraction peaks of the molecular sieve remains basically the same before and after the surface hydrocarbonophilic modification, and the peak positions do not shift. The results prove that the crystal form of ZSM-5 molecular sieve does not change after the surface hydrocarbonophilic modification; Figure 3 is the FT-IR image of Comparative Example 1. At 1620 cm -1 and 3480 cm -1 are the stretching vibration peaks of -OH of the crystal water in ZSM-5. At 1000 cm -1 is the stretching vibration peak of the SiO4 tetrahedron; Figure 4 is the FT-IR image of Example 2. The added stretching vibration peak at 1460 cm -1 is for -CH2-. The overtone peaks at 1868 cm -1 and 2006 cm -1 are for substituted benzenes. By comparing the two figures, it is found that for the molecular sieve after the surface hydrocarbonophilic modification, in addition to the original peaks of the molecular sieve, peaks at 2006, 1868, and 1460 are also added, indicating the successful adsorption of aromatics. Figure 5 is the structural formula of the substance with the highest content in the extraction liquid obtained by extracting coal tar with different solvents. Figure 6 is the SEM image of the ZSM-5 adsorbent of the present invention; among them, (a) is the unmodified ZSM-5 adsorbent of Comparative Example 1, (b) is the enlarged view of (a), (c) is the ZSM-5 adsorbent with surface hydrocarbonophilic modification of Example 2, and (d) is the enlarged view of (c). It can be seen from Figure 6 that the ZSM-5 molecular sieve of Comparative Example 1 presents a hexagonal structure, and the single particle structure is about 200 - 300 nm, with a certain degree of agglomeration. The microscopic morphology of the ZSM-5 molecular sieve after the surface hydrocarbonophilic modification of Example 2 is basically unchanged.

[0076] Evaluation of adsorption and desorption performance:

[0077] For the adsorbents with surface hydrocarbonophilic modification in Examples 1 - 10, the saturated adsorption amounts of N2 and CH4 were measured. 0.2 g of the adsorbent was loaded into a quartz tube, vacuum desorbed at 120 o °C for 3 h, and then pure N2 or pure CH4 was introduced to measure the adsorption curve. The test temperature was 273 K, and the test pressure range was 2 - 100 kPa. After the test, the saturated adsorption amount of the adsorbent was calculated by fitting with the Langmuir equation. The results are shown in Table 1:

[0078]

[0079] The results show that the saturated adsorption capacity of CH4 generally increases through surface hydrocarbonophilic modification, while the saturated adsorption capacity of N2 decreases slightly. Zeolites with a high silica-alumina ratio are more likely to adsorb aromatic substances, so the modification effect is more ideal. The adsorption of aromatics significantly reduces the framework polarity and is miscible with CH4 in accordance with the principle of like dissolves like, which is the reason for the increase in the CH4 adsorption capacity. The surface hydrocarbonophilic modification liquid obtained by extracting medium-temperature coal tar pitch with n-heptane shows the best modification effect. Moreover, both the mass ratio of the zeolite to the hydrocarbonophilic modification liquid and the impregnation time have an impact on the modification effect. A low mass ratio and a long impregnation time lead to excessive adsorption of aromatic substances, resulting in pore blockage. Selecting a single long-chain alkane for impregnation shows an unsatisfactory modification effect, and the ion exchange modification strategy is also ineffective due to the high silica-alumina ratio of the zeolite.

[0080] For the adsorbents with surface hydrocarbonophilic modification in Examples 1 - 10, a pressure swing adsorption test of low-concentration mine gas was carried out. 50 g of the 20 - 40 mesh adsorbent after tabletting and granulation was loaded into the adsorption column, and vacuum desorption was carried out at room temperature for 10 min. Then, the low-concentration mine gas raw material gas CH4:N2 (the volume fraction of CH4 was 0.37%) was introduced at a flow rate of 500 mL / min for rapid backpressure operation. When the pressure reached 0.6 MPa, the gas supply was stopped. The adsorption pressure was 0.6 MPa, and the adsorption temperature was room temperature (25°C). After 10 min, the pressure was released and vacuum desorption was carried out. The desorbed gas was collected and its concentration was analyzed using a methane concentration analyzer. The results are shown in Table 2:

[0081]

[0082] The results show that the surface hydrocarbonophilic modified ZSM-5 zeolite can concentrate low-concentration mine gas, corresponding to the results of the saturated adsorption capacity measurement. The surface hydrocarbonophilic modification liquid obtained by extracting medium-temperature coal tar pitch with n-heptane shows the best modification effect, and the modified ZSM-5 zeolite has the most excellent performance in concentrating low-concentration mine gas.

[0083] For the adsorbents with surface hydrocarbonophilic modification in Examples 1 - 10, a stability test of low-concentration mine gas pressure swing adsorption was carried out. 5 g of the 20 - 40 mesh adsorbent was loaded into the adsorption column, and vacuum desorption was carried out at room temperature for 10 min. Then, a breakthrough experiment was carried out by introducing the low-concentration mine gas raw material gas CH4:N2 (the volume fraction of CH4 was 0.37%). The adsorption pressure was atmospheric pressure, the adsorption temperature was room temperature, and the flow rate of the raw material gas was 100 mL / min. After complete breakthrough, the above experimental operations were repeated for a total of ten cycles. The methane concentration analyzer was connected to the tail end of the adsorption device, and the recorded breakthrough time was after deducting the dead volume and the response time of the methane concentration analyzer. The results are shown in Table 3:

[0084]

[0085] Obviously, the ZSM-5 molecular sieve adsorbent after surface hydrocarbonophilic modification has good cycle stability, and the adsorption performance shows no obvious decline after ten cycles. Therefore, compared with the traditional ion exchange modification measures, the surface hydrocarbonophilic modification shows the advantages of simple operation and wide applicability.

[0086] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific embodiments of the present invention are limited thereto. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the present invention, several simple deductions or substitutions can still be made, which should all be regarded as belonging to the patent protection scope determined by the claims submitted by the present invention.

Claims

1. A preparation method of a surface-hydrocarbonophilic modified ZSM-5 molecular sieve adsorbent, characterized in that, It includes the following steps: S1. Use n-heptane to extract medium-temperature coal tar pitch, and the obtained extraction liquid is used as the surface hydrocarbonophilic modification liquid; S2. Mix and impregnate ZSM-5 molecular sieve with a silica-alumina ratio of 100 and the surface hydrocarbonophilic modification liquid at room temperature, and then obtain a surface hydrocarbonophilic modified ZSM-5 molecular sieve adsorbent through filtration and drying; the mass ratio of ZSM-5 molecular sieve to the surface hydrocarbonophilic modification liquid is 1:1 to 1:10, and the impregnation time is 12 to 48 h; The ZSM-5 molecular sieve adsorbent is used for the concentration of exhausted mine gas.

2. The preparation method of a surface-hydrocarbonophilic modified ZSM-5 molecular sieve adsorbent according to claim 1, characterized in that, The mass ratio of medium-temperature coal tar pitch to the organic extractant is 1:

5.

3. The preparation method of a surface hydrocarbonophilic modified ZSM-5 molecular sieve adsorbent according to claim 1, characterized in that The extraction is to put medium-temperature coal tar pitch into the organic extractant and stir.

4. The preparation method of a surface-hydrocarbonophilic modified ZSM-5 molecular sieve adsorbent according to claim 3, wherein The temperature of the extraction is 50 to 70 °C, the stirring speed is 350 to 450 r / min, and the stirring time is 2 - 3 h.

5. The preparation method of a surface hydrocarbonophilic modified ZSM-5 molecular sieve adsorbent according to claim 4, characterized in that, After extraction, suction filtration is carried out to obtain the extraction liquid.

6. The preparation method of a surface hydrocarbonophilic modified ZSM-5 molecular sieve adsorbent according to claim 1, characterized in that, The drying is carried out in an oven at 40 to 80 °C for 12 to 48 h.

7. A surface-hydrocarbonophilic modified ZSM-5 molecular sieve adsorbent, characterized in that, It is prepared by using the preparation method of a surface hydrocarbonophilic modified ZSM-5 molecular sieve adsorbent according to any one of claims 1 - 6.

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