A molecular sieve adsorbent for removing thiophene sulfides from oil products and a method for preparing the same

Abstract

The present application relates to the technical field of adsorption desulfurization, and particularly relates to a molecular sieve adsorbent for removing thiophene sulfides in oil products and a preparation method thereof, the preparation method comprising the following steps: (1) preparation of a ZIF-67 precursor suspension; (2) preparation of a gamma-Al2O3 carrier; (3) pretreatment of the gamma-Al2O3 carrier; (4) carrier assembly and in-situ bonding; (5) post-treatment: separating, washing, drying and cooling the product of step (4), thereby obtaining the molecular sieve adsorbent. The adsorbent has high adsorption capacity for thiophene sulfides and strong target selectivity, and can achieve deep removal of thiophene sulfides in various oil products.

Description

Technical Field

[0001] This invention relates to the field of adsorption desulfurization technology, and in particular to a molecular sieve adsorbent for removing thiophene sulfides from oil products and its preparation method. Background Technology

[0002] With increasingly stringent environmental regulations, reducing the sulfur content in petroleum products has become a core requirement in the fuel processing industry. Thiophene sulfides, which are difficult to remove and highly harmful sulfides in petroleum products, are commonly removed using hydrodesulfurization technology. However, hydrodesulfurization requires high temperature and high pressure conditions, resulting in high hydrogen consumption and significant octane number loss. Among non-hydrodesulfurization technologies, adsorption desulfurization has become a research hotspot due to its advantages of mild conditions and low cost.

[0003] Commonly used adsorbents in existing technologies, such as zeolite-type imidazoline frameworks (ZIFs) in metal-organic frameworks (MOFs), like ZIF-67, possess high porosity, uniform unsaturated metal sites, and excellent stability, exhibiting a certain adsorption capacity for thiophene sulfides. An article published in *Materials Chemistry and Physics*, issue 334, number 130499, entitled "A combined experimental and computational studies on thiophene adsorption from liquid fuels over ZIF-67@ZnFeLDH composites," mentions a ZIF-67@ZnFeLDH adsorbent for removing thiophene from n-heptane model fuel. However, the synthesis process of this ZIF-67 did not consider the problems of ZIF-67's tendency to aggregate and uneven distribution, resulting in weak binding with the support, low mechanical strength, and difficulties in separation and recovery, thus limiting its industrial application.

[0004] Chinese invention patent CN120605689A discloses a desulfurization adsorbent for low-carbon olefins and its preparation method. This invention patent utilizes an adsorbent primarily composed of zeolite molecular sieves to adsorb total sulfur from simulated oil. This adsorbent features high adsorption capacity and low temperature rise during adsorption. However, its adsorption range is limited to low-carbon olefins, resulting in a narrow application scope. It cannot adsorb thiophene sulfur, which is present in high concentrations in real oil products and is difficult to remove. Furthermore, it requires pretreatment with inert gas at 350℃ for 2 hours before use, making the operating conditions complex.

[0005] Chinese invention patent CN120248929A discloses a method and application for green and efficient removal of thiophene sulfides from fuel oil using Q[8]. This invention patent uses Q[8] solid powder material to remove thiophene sulfides from fuel oil through a host-guest interaction mechanism. The operation is simple, convenient, and low-cost, but its removal rate of thiophene sulfides in fuel oil is 92%, and there is still room for further improvement in removal efficiency.

[0006] Therefore, there is an urgent need to develop an adsorption material for removing thiophene sulfides from oil products, so as to achieve efficient and deep removal of thiophene sulfides from various oil products. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention provides a molecular sieve adsorbent for removing thiophene sulfides from oil products. The molecular sieve adsorbent of this invention exhibits high adsorption capacity and strong targeting selectivity for thiophene sulfides, enabling deep removal of thiophene sulfides from various oil products.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention provides a method for preparing a molecular sieve adsorbent for removing thiophene sulfides from oil products, comprising the following steps: (1) Preparation of ZIF-67 precursor suspension: The 2-methylimidazolium mother liquor was ultrasonically dispersed and then added dropwise to a methanol solution of Co(NO3)2·6H2O. The mixture was stirred thoroughly at 25-30℃ until precipitation. After centrifugation, washing and drying, ZIF-67 precursor was obtained. Deionized water was then added to prepare a ZIF-67 precursor suspension with a concentration of 0.1-0.3 g / mL. (2) Preparation of γ-Al2O3 support: Under the stirring conditions of 65-75℃ and 200-350rpm, sodium aluminate solution was taken, the pH was adjusted to 7.7~8.3, the precipitate was separated and mixed with deionized water, and stirred at 60-80℃ for 20-60min to obtain aluminum hydroxide slurry. Then, gelling agent and pore-forming agent were added, and the mixture was stirred until uniform. After drying, calcination and sieving, γ-Al2O3 support was obtained. (3) Pretreatment of γ-Al2O3 support: The γ-Al2O3 support from step (2) is mixed with the modifier, heated to 170-175℃, treated for 2-3 hours, and then washed and dried to obtain the pretreated γ-Al2O3 support. (4) Carrier assembly and in-situ bonding: The pretreated γ-Al2O3 carrier from step (3) was added to the 0.1-0.3 g / mL ZIF-67 precursor suspension from step (1), stirred at room temperature until fully mixed, allowed to stand for 0.5-2 h, and then 0.1-0.3 mol / L of 2-methylimidazole methanol solution was slowly added. After the addition was complete, the mixture was stirred for 1-3 h to obtain the product. (5) Post-processing: The product of step (4) is separated, washed, mixed with methanol, treated at 70-90℃ for 10-14h, and then cooled after heating to obtain the molecular sieve adsorbent.

[0009] In some embodiments of the present invention, the 2-methylimidazole mother liquor in step (1) is an aqueous solution of 2-methylimidazole with a concentration of 0.05-0.07 g / mL.

[0010] In some embodiments of the present invention, the concentration of the methanol solution of Co(NO3)2·6H2O in step (1) is 0.02-0.04 g / mL.

[0011] In some embodiments of the present invention, the mass ratio of 2-methylimidazole and Co(NO3)2·6H2O in step (1) is 6.0~7.0:2.5~3.5.

[0012] In some embodiments of the present invention, the concentration of the sodium aluminate solution in step (2) is 0.5~1.5 mol / L.

[0013] In some embodiments of the present invention, the ratio of sodium aluminate solution, deionized water, gelling agent and pore-forming agent in step (2) is 200mL: 300-500mL: 1-3g: 0.5-2g.

[0014] Preferably, the gelling agent is urea.

[0015] Preferably, the pore-forming agent is polyethylene glycol.

[0016] More preferably, the number-average molecular weight of the polyethylene glycol is 4000.

[0017] In some embodiments of the present invention, the calcination in step (2) is performed at a temperature of 530~570°C for 2.5~3.5 hours.

[0018] In some embodiments of the present invention, the particle size of the γ-Al2O3 support in step (2) is 3~5 mm.

[0019] In some embodiments of the present invention, the preparation steps of the modifier in step (3) are as follows: Soluble cerium salt, deionized water and ethanol are mixed until homogeneous, heated to 60-70℃, and dibenzo-18-crown ether-6 is added while stirring. The mixture is stirred for 2-4 hours to obtain the modifier.

[0020] In some embodiments of the present invention, the soluble cerium salt is cerium nitrate and / or cerium chloride.

[0021] In some embodiments of the present invention, the mass ratio of the soluble cerium salt to dibenzo-18-crown ether-6 is 1:(0.9-1.1).

[0022] In some embodiments of the present invention, the mass ratio of the γ-Al2O3 support to the modifier in step (3) is 1:(0.3-0.5).

[0023] In some embodiments of the present invention, the ratio of the addition of the γ-Al2O3 support, the ZIF-67 precursor suspension and the methanol solution of 2-methylimidazole in step (4) is 1.8~2.2g: 48~52mL: 45~55mL.

[0024] A second aspect of the present invention also provides a molecular sieve adsorbent obtained by the above preparation method.

[0025] This invention uses ZIF-67 as the metal framework and Co²⁺ as the base metal. + Centered on Zn², its unsaturated coordination sites far outnumber those that are saturated. + This provides a key active center for adsorption, and single Co² + The central structure is more uniform, the stability is better, and the performance repeatability is higher.

[0026] This invention uses γ-Al2O3 as an adsorbent carrier and further pre-modifies it, thereby improving its thermal stability and providing "thermal protection" for ZIF-67. This ensures that the crystal structure of ZIF-67 remains intact during the programmed temperature rise, adsorption, and regeneration processes after synthesis, extending the adsorbent's lifespan. Furthermore, the 2-50 nm pores of γ-Al2O3 can act as a "nanoreactor," limiting the size of ZIF-67 and giving the ZIF-67 crystals a larger specific surface area and more exposed active sites.

[0027] Specifically, the ZIF-67 metal framework and γ-Al2O3 support of this invention achieve a further improvement in the efficiency of dethiophene sulfide removal. This is likely due to the presence of a large number of -OH groups and uniformly distributed cerium ions on the surface of the pre-modified γ-Al2O3, which interact with the cobalt ions or organic ligands during the synthesis of ZIF-67, providing strong anchoring sites and ensuring that ZIF-67 can grow firmly on the support. The "anchoring effect" further enhances the binding strength between ZIF-67 and the support, avoiding performance degradation caused by phase separation and ZIF-67 detachment during adsorption, thus ensuring the adsorption effect and extending the service life of the molecular sieve adsorbent. Furthermore, the applicant has also discovered that the simultaneous presence of Lewis acidic and basic sites on the surface of the γ-Al2O3 support may further enhance the electronic interaction with ZIF-67, effectively optimizing the adsorption performance of the molecular sieve adsorbent.

[0028] Compared with the prior art, the present invention has the following beneficial effects: (1) The molecular sieve adsorbent prepared by the present invention has high adsorption capacity and strong targeting selectivity for thiophene sulfides, and can achieve deep removal of thiophene sulfides from various oil products.

[0029] (2) This invention uses ZIF-67 as the metal skeleton and Co²⁻ as the base metal. + Centered on γ-Al2O3 as the adsorbent carrier and further pre-modified it, ZIF-67 is provided with "thermal protection" and the ZIF-67 crystals have a larger specific surface area and more exposed active sites. Together, these factors have further improved the removal efficiency and effect of molecular sieve adsorbents on thiophene sulfides. Detailed Implementation

[0030] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0031] Unless otherwise specified, the compound raw materials and related reagents used in the following specific embodiments can be purchased from the market.

[0032] Unless otherwise specified, the post-processing steps such as "centrifugation", "washing", "drying" and "cooling" used in the following specific embodiments are routine operations for those skilled in the art, and can be selected according to actual operation.

[0033] Preparation Example 1 The preparation steps of the modifier are as follows: Mix 5g of cerium nitrate (Ce(NO3)3·6H2O), 15mL of deionized water and 15mL of ethanol until homogeneous, heat to 65℃, add 5g of dibenzo-18-crown ether-6 while stirring, and stir for 3h to obtain the modifier.

[0034] Preparation Example 2 The specific preparation steps of the modifier are the same as those in Preparation Example 1, except that the amount of dibenzo-18-crown ether-6 added is 5.8g.

[0035] Preparation Example 3 The specific preparation steps of the modifier are the same as those in Preparation Example 1, except that dibenzo-18-crown ether-6 is not added.

[0036] Example 1 A method for preparing a molecular sieve adsorbent for removing thiophene sulfides from oil products includes the following steps: (1) Preparation of ZIF-67 precursor suspension: The 2-methylimidazolium mother liquor (6.5 g 2-methylimidazolium dissolved in 100 mL deionized water) was ultrasonically dispersed and then added dropwise to the methanol solution of Co(NO3)2·6H2O (3.0 g Co(NO3)2·6H2O dissolved in 100 mL methanol). The mixture was stirred thoroughly at 28℃ until precipitation occurred. After centrifugation, washing with methanol three times and drying at 80℃ for 18 h, the ZIF-67 precursor was obtained. Deionized water was then added to prepare a ZIF-67 precursor suspension with a concentration of 0.2 g / mL. (2) Preparation of γ-Al2O3 support: Under the stirring conditions of 70℃ and 300rpm, take 200mL of 1mol / L sodium aluminate solution, adjust the pH to 8, and after separation, take the precipitate and mix it with 400mL of deionized water. Stir at 70℃ for 30min to obtain aluminum hydroxide slurry, then add 2g of urea and 1g of polyethylene glycol (number average molecular weight 4000), stir until uniform, dry at 100℃ for 1h, calcine at 550℃ for 3h, and screen to obtain spherical particles with a particle size of 3~5 mm to obtain γ-Al2O3 support; (3) Pretreatment of γ-Al2O3 support: 10g of γ-Al2O3 support from step (2) and 4g of modifier are mixed, heated to 172℃, treated for 2.5h, washed 3 times with deionized water and ethanol alternately, and dried at 70℃ for 2h to obtain pretreated γ-Al2O3 support. (4) Carrier assembly and in-situ bonding: 2g of the pretreated γ-Al2O3 carrier from step (3) was added to 50mL of the 0.2g / mL ZIF-67 precursor suspension from step (1), and stirred at 25℃ and 300 rpm for 2h to mix thoroughly. After standing for 1h, 50mL of 0.2mol / L 2-methylimidazole methanol solution was added at a rate of 2mL / min. After the addition was completed, the mixture was stirred for 2h to obtain the product. (5) Post-processing: All products from step (4) are centrifuged at 4000 r / min for 10 min, washed three times with methanol, mixed with 30 mL of methanol, treated at 80 °C for 12 h, and then heated from room temperature to 100 °C at 2 °C / min and kept at 1 h. After cooling to room temperature, the molecular sieve adsorbent is obtained.

[0037] The modifier in this embodiment was obtained from Preparation Example 1.

[0038] Example 2 A method for preparing a molecular sieve adsorbent for removing thiophene sulfides from oil products includes the following steps: (1) Preparation of ZIF-67 precursor suspension: The 2-methylimidazolium mother liquor (6 g 2-methylimidazolium dissolved in 100 mL deionized water) was ultrasonically dispersed and then added dropwise to a methanol solution of Co(NO3)2·6H2O (2.5 g Co(NO3)2·6H2O dissolved in 100 mL methanol). The mixture was stirred thoroughly at 25 °C until precipitation occurred. After centrifugation, washing with methanol three times and drying at 80 °C for 18 h, ZIF-67 precursor was obtained. Deionized water was then added to prepare a ZIF-67 precursor suspension with a concentration of 0.2 g / mL. (2) Preparation of γ-Al2O3 support: Under the conditions of stirring at 70℃ and 300rpm, take 200mL of 1mol / L sodium aluminate solution, adjust the pH to 8, and after separation, take the precipitate and mix it with 400mL of deionized water. Stir at 70℃ for 30min to obtain aluminum hydroxide slurry, then add 1g of urea and 0.5g of polyethylene glycol (number average molecular weight 4000), stir until uniform, dry at 100℃ for 1h, calcine at 550℃ for 3h, and screen to obtain spherical particles with a particle size of 3~5 mm to obtain γ-Al2O3 support; (3) Pretreatment of γ-Al2O3 support: 10g of γ-Al2O3 support from step (2) and 3g of modifier are mixed, heated to 170℃, treated for 3h, washed 3 times with deionized water and ethanol alternately, and dried at 70℃ for 2h to obtain pretreated γ-Al2O3 support. (4) Carrier assembly and in-situ bonding: 1.8g of the pretreated γ-Al2O3 carrier from step (3) was added to 50mL of the 0.2g / mL ZIF-67 precursor suspension from step (1). The mixture was stirred at 25℃ and 300 rpm for 2h to fully mix. After standing for 1h, 50mL of 0.2mol / L 2-methylimidazole methanol solution was added at a rate of 2mL / min. After the addition was completed, the mixture was stirred for 2h to obtain the product. (5) Post-processing: All products from step (4) are centrifuged at 4000 r / min for 10 min, washed three times with methanol, mixed with 30 mL of methanol, treated at 80 °C for 12 h, and then heated from room temperature to 100 °C at 2 °C / min and kept at 1 h. After cooling to room temperature, the molecular sieve adsorbent is obtained.

[0039] The modifier in this embodiment was obtained from Preparation Example 1.

[0040] Example 3 A method for preparing a molecular sieve adsorbent for removing thiophene sulfides from oil products includes the following steps: (1) Preparation of ZIF-67 precursor suspension: The 2-methylimidazolium mother liquor (7 g 2-methylimidazolium dissolved in 100 mL deionized water) was ultrasonically dispersed and then added dropwise to a methanol solution of Co(NO3)2·6H2O (3.5 g Co(NO3)2·6H2O dissolved in 100 mL methanol). The mixture was stirred thoroughly at 28℃ until precipitation occurred. After centrifugation, washing with methanol three times and drying at 80℃ for 18 h, ZIF-67 precursor was obtained. Deionized water was then added to prepare a ZIF-67 precursor suspension with a concentration of 0.2 g / mL. (2) Preparation of γ-Al2O3 support: Under the stirring conditions of 70℃ and 300rpm, take 200mL of 1mol / L sodium aluminate solution, adjust the pH to 8, and after separation, take the precipitate and mix it with 400mL of deionized water. Stir at 70℃ for 30min to obtain aluminum hydroxide slurry, then add 3g of urea and 2g of polyethylene glycol (number average molecular weight 4000), stir until uniform, dry at 100℃ for 1h, calcine at 550℃ for 3h, and screen to obtain spherical particles with a particle size of 3~5 mm to obtain γ-Al2O3 support; (3) Pretreatment of γ-Al2O3 support: 10g of γ-Al2O3 support from step (2) and 5g of modifier are mixed, heated to 175℃, treated for 2h, washed 3 times with deionized water and ethanol alternately, and dried at 70℃ for 2h to obtain pretreated γ-Al2O3 support. (4) Carrier assembly and in-situ bonding: 2.2g of the pretreated γ-Al2O3 carrier from step (3) was added to 50mL of the 0.2g / mL ZIF-67 precursor suspension from step (1). The mixture was stirred at 25℃ and 300 rpm for 2h to mix thoroughly. After standing for 1h, 50mL of 0.2mol / L 2-methylimidazole methanol solution was added at a rate of 2mL / min. After the addition was completed, the mixture was stirred for 2h to obtain the product. (5) Post-processing: All products from step (4) are centrifuged at 4000 r / min for 10 min, washed three times with methanol, mixed with 30 mL of methanol, treated at 80 °C for 12 h, and then heated from room temperature to 100 °C at 2 °C / min and kept at 1 h. After cooling to room temperature, the molecular sieve adsorbent is obtained.

[0041] The modifier in this embodiment was obtained from Preparation Example 1.

[0042] Example 4 A method for preparing a molecular sieve adsorbent for removing thiophene sulfides from oil products, the specific implementation method is the same as in Example 1, the difference being that the modifier in this example is obtained from Preparation Example 2.

[0043] Example 5 A method for preparing a molecular sieve adsorbent for removing thiophene sulfides from oil products, the specific implementation method is the same as in Example 1, the difference being that the modifier in this example is obtained from Preparation Example 3.

[0044] Example 6 A method for preparing a molecular sieve adsorbent for removing thiophene sulfides from oil products, the specific implementation method is the same as in Example 1, the difference being that the amount of modifier added in this example is 5.5g.

[0045] Comparative Example 1 (1) Preparation of ZIF-67 precursor suspension: The 2-methylimidazolium mother liquor (6.5 g 2-methylimidazolium dissolved in 100 mL deionized water) was ultrasonically dispersed and then added dropwise to the methanol solution of Co(NO3)2·6H2O (3.0 g Co(NO3)2·6H2O dissolved in 100 mL methanol). The mixture was stirred thoroughly at 28℃ until precipitation occurred. After centrifugation, washing with methanol three times and drying at 80℃ for 18 h, the ZIF-67 precursor was obtained. Deionized water was then added to prepare a ZIF-67 precursor suspension with a concentration of 0.2 g / mL. (2) Preparation of γ-Al2O3 support: Under the stirring conditions of 70℃ and 300rpm, take 200mL of 1mol / L sodium aluminate solution, adjust the pH to 8, and after separation, take the precipitate and mix it with 400mL of deionized water. Stir at 70℃ for 30min to obtain aluminum hydroxide slurry, then add 2g of urea and 1g of polyethylene glycol (number average molecular weight 4000), stir until uniform, dry at 100℃ for 1h, calcine at 550℃ for 3h, and screen to obtain spherical particles with a particle size of 3~5 mm to obtain γ-Al2O3 support; (3) Carrier assembly and in-situ bonding: 2g of the γ-Al2O3 carrier from step (2) was added to 50mL of the 0.2g / mL ZIF-67 precursor suspension from step (1), and stirred at 25℃ and 300 rpm for 2h to mix thoroughly. After standing for 1h, 50mL of 0.2mol / L 2-methylimidazole methanol solution was added at a rate of 2mL / min. After the addition was completed, the mixture was stirred for 2h to obtain the product. (4) Post-processing: All products from step (3) are centrifuged at 4000 r / min for 10 min, washed three times with methanol, mixed with 30 mL of methanol, treated at 80 °C for 12 h, and then heated from room temperature to 100 °C at 2 °C / min and kept at 1 h. After cooling to room temperature, the molecular sieve adsorbent is obtained.

[0046] Performance testing Test 1:Take 1g of the molecular sieve adsorbent prepared in each example and comparative example and add it to 800 mL of real oil (pretreated to remove water and solid impurities). The adsorption experiment was carried out at 25℃ and 220 rpm for 12h. The sulfur content in the oil before and after adsorption was determined by ultraviolet fluorescence sulfur analyzer (GB / T 11060.8), and the sulfur content of thiophene was determined by gas chromatography-sulfur chemiluminescence detector (GC-SCD).

[0047] The actual oil product comes from catalytic cracking gasoline produced by a company in Nanjing, China Petroleum & Chemical Corporation (Sinopec). The initial sulfur composition is as follows: total sulfur 150.0 ppm, including: thiophene 30.0 ppm, methylthiophene 25.0 ppm, dimethylthiophene 20.0 ppm, and other sulfur 75.0 ppm.

[0048] The test results are shown in Table 1 below: Table 1

[0049] As shown in Table 1, the molecular sieve adsorbents obtained in Examples 1-3 of this invention have significant advantages in terms of total sulfur removal rate and thiophene sulfur removal rate. A comparison between Example 4 and Example 1 shows that changing the amount of dibenzo-18-crown ether-6 may lead to competitive adsorption, affecting the formation of active sites and thus the removal effect. A comparison between Example 5 and Example 1 shows that not adding dibenzo-18-crown ether-6 may affect the uniformity and stability of the distribution of supplementary active sites, and also affects the interaction with ZIF-67, resulting in varying degrees of decrease in total sulfur removal rate and thiophene sulfur removal rate. A comparison between Example 6 and Example 1 shows that changing the amount of modifier may lead to pore blockage and decreased dispersion, which is detrimental to the removal process and reduces removal performance. A comparison between Comparative Example 1 and Example 1 shows that when γ-Al2O3 is pretreated without a modifier, its desulfurization effect is affected by adsorption capacity, selectivity, and stability, but there is still room for improvement.

[0050] Test 2: 1g of the molecular sieve adsorbent prepared in Example 1 was added to 800 mL of oil product a and oil product b respectively, and adsorption experiments were conducted at 25℃ and 220 rpm for 12 h. The sulfur content in the oil before and after adsorption was determined by ultraviolet fluorescence sulfur analyzer (GB / T 11060.8), and the thiophene sulfur content was determined by gas chromatography-sulfur chemiluminescence detector (GC-SCD). The oils were pretreated to remove moisture and solid impurities. a: High thiophene, low mercaptan oil (source: catalytic gasoline component from a Sinopec company in Zhejiang). Initial sulfur composition is as follows: total sulfur 210.0 ppm, including: thiophene 85.0 ppm, methylthiophene 40.0 ppm, ethanethiol 15.0 ppm, and other sulfur (such as sulfides) 70.0 ppm.

[0051] b: Thiophene and mercaptan oil of equal concentration (source: inferior naphtha from a certain company of China National Petroleum Corporation in Lanzhou). The initial sulfur composition is as follows: total sulfur 125.0 ppm, of which: thiophene 50.0 ppm, n-propanethiol 50.0 ppm, and other sulfur (such as disulfides) 25.0 ppm.

[0052] The test results are shown in Table 2 below: Table 2

[0053] As shown in Table 2, when the molecular sieve adsorbent prepared in Example 1 was used in oil product a, the removal rate of thiophene sulfides was higher than that of total sulfur, showing excellent selectivity. When the molecular sieve adsorbent prepared in Example 1 was used in oil product b, the test results showed that its removal efficiency of thiophene sulfides was still significantly higher than that of total sulfur, demonstrating its strong targeted adsorption performance for thiophene.

[0054] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing a molecular sieve adsorbent for removing thiophene sulfides from oil products, characterized in that, The preparation method includes the following steps: (1) Preparation of ZIF-67 precursor suspension: The 2-methylimidazolium mother liquor was ultrasonically dispersed and then added dropwise to a methanol solution of Co(NO3)2·6H2O. The mixture was stirred thoroughly at 25-30℃ until precipitation occurred. After centrifugation, washing and drying, ZIF-67 precursor was obtained. Deionized water was then added to prepare a ZIF-67 precursor suspension with a concentration of 0.1-0.3 g / mL. (2) Preparation of γ-Al2O3 support: Under stirring conditions of 65~75℃, the pH of sodium aluminate solution was adjusted to 7.7~8.

3. After separation, the precipitate was mixed with deionized water to obtain aluminum hydroxide slurry. Then, gelling agent and pore-forming agent were added, stirred until uniform, dried, calcined and sieved to obtain γ-Al2O3 support. (3) Pretreatment of γ-Al2O3 support: The γ-Al2O3 support from step (2) is mixed with the modifier, heated to 170-175℃, treated for 2-3 hours, and then washed and dried to obtain the pretreated γ-Al2O3 support. (4) Carrier assembly and in-situ bonding: The pretreated γ-Al2O3 carrier from step (3) is added to the 0.1-0.3 g / mL ZIF-67 precursor suspension from step (1), stirred until fully mixed, and then 0.1-0.3 mol / L of 2-methylimidazole methanol solution is added and stirred for 1-3 h to obtain the product. (5) Post-processing: The product of step (4) is separated, washed, dried and cooled to obtain the molecular sieve adsorbent.

2. The method for preparing the molecular sieve adsorbent for removing thiophene sulfides from oil products according to claim 1, characterized in that, The mass ratio of 2-methylimidazole and Co(NO3)2·6H2O in step (1) is 6.0~7.0:2.5~3.

5.

3. The method for preparing the molecular sieve adsorbent for removing thiophene sulfides from oil products according to claim 1, characterized in that, The ratio of sodium aluminate solution, deionized water, gelling agent and pore-forming agent used in step (2) is 200mL: 300-500mL: 1-3g: 0.5-2g.

4. The method for preparing the molecular sieve adsorbent for removing thiophene sulfides from oil products according to claim 1, characterized in that, The calcination in step (2) is carried out at a temperature of 530~570℃ for 2.5~3.5h.

5. The method for preparing the molecular sieve adsorbent for removing thiophene sulfides from oil products according to claim 1, characterized in that, The particle size of the γ-Al2O3 support in step (2) is 3~5 mm.

6. The method for preparing the molecular sieve adsorbent for removing thiophene sulfides from oil products according to claim 1, characterized in that, The preparation steps of the modifier mentioned in step (3) are as follows: The soluble cerium salt and deionized water are mixed until homogeneous, heated to 55-60℃, and dibenzo-18-crown ether-6 is added while stirring. The mixture is stirred for 0.5-1h to obtain the modifier.

7. The method for preparing the molecular sieve adsorbent for removing thiophene sulfides from oil products according to claim 6, characterized in that, The mass ratio of the soluble cerium salt to dibenzo-18-crown ether-6 is 1:(0.9-1.1).

8. The method for preparing the molecular sieve adsorbent for removing thiophene sulfides from oil products according to claim 6, characterized in that, The mass ratio of γ-Al2O3 carrier to modifier in step (3) is 1:(0.3-0.5).

9. The method for preparing the molecular sieve adsorbent for removing thiophene sulfides from oil products according to claim 6, characterized in that, The ratio of the addition of γ-Al2O3 support, ZIF-67 precursor suspension and 2-methylimidazole methanol solution in step (4) is 1.8~2.2g: 48~52mL: 45~55mL.

10. A molecular sieve adsorbent for removing thiophene sulfides from oil products, obtained by the preparation method according to any one of claims 1-9.

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