Composite material for extracting and removing thiophene as well as preparation method and application of composite material

Abstract

The invention belongs to the technical field of extraction separation, and discloses a composite material for extracting and removing thiophene as well as a preparation method and application of the composite material. According to the method, the deep eutectic solvent is loaded on the phosphorus-doped carbon nitride, and the thiophene sulfide in the fuel oil is synergistically removed by utilizing the extraction of the deep eutectic solvent and the adsorption of the phosphorus-doped carbon nitride. According to the method, the three modes of extraction, oxidation and adsorption are used for synergic desulfurization, the operation conditions are mild, the desulfurization efficiency is high, the defect that the deep eutectic solvent is inconvenient to transport and store in industry is overcome, and the thiophene removal efficiency close to 99.9% is achieved.

Description

Technical Field

[0001] This invention belongs to the field of extraction and separation technology. It relates to a composite material for extracting and removing thiophene, its preparation method, and its application. Background Technology

[0002] With the rapid development of the global economy, the consumption of fossil fuels continues to rise. The sulfur components in fuel oil are converted into sulfur oxides (SO₄²⁻) upon combustion. x Mainly includes SO2 and SO3) and fine particulate matter (PM2.5). 2.5 These pollutants not only easily induce acid rain and aggravate smog, but also seriously threaten atmospheric ecology and human health. Among the various sulfides contained in fuel oil, thiophene and its derivatives (such as benzothiophene, dibenzothiophene, etc.) are the core challenges in deep desulfurization. Currently, hydrodesulfurization technology is widely used in industry, but it requires operation under high temperature and pressure, which makes it difficult to efficiently remove aromatic sulfides and also reduces the octane number of fuel oil. Non-hydrodesulfurization technology, which has mild reaction conditions and high removal efficiency for thiophene sulfides, has become an important alternative to hydrodesulfurization. It includes methods such as biological desulfurization, oxidative desulfurization, extraction desulfurization, and adsorption desulfurization. Among them, extraction desulfurization and oxidative adsorption desulfurization are considered to be highly promising deep desulfurization processes due to their simple operation, high selectivity, and small impact on the octane number of fuel oil.

[0003] Extractive desulfurization technology is an important branch of non-hydrogenated fuel desulfurization, mainly including oxidative extraction desulfurization, complexation extraction desulfurization, ionic liquid extraction desulfurization, acid-base washing desulfurization, and deep eutectic solvent extraction desulfurization. In recent years, deep eutectic solvent desulfurization has received widespread attention due to its similar physicochemical properties to ionic liquids, simple synthesis process, environmental friendliness, and low cost, effectively overcoming the bottleneck of high cost associated with traditional ionic liquids. However, because deep eutectic solvents are liquid, their industrial storage and transportation still face significant challenges. Patent CN 120137694 A discloses a method for preparing a composite extractive-oxidative-adsorption desulfurization material. Its core involves loading a deep eutectic solvent onto graphitic carbon nitride@graphene oxide nanospheres, which exhibits high desulfurization efficiency in the removal of thiophene sulfides. However, the core carrier, graphitic carbon nitride@graphene oxide nanospheres, is synthesized using a hydrothermal method, which is not only complex but also results in low product yield, making it difficult to meet the needs of industrial-scale mass production. Patent CN 110922386 A discloses a method for extracting thiophene by loading a deep eutectic solvent onto carbon nanotubes. Under optimal desulfurization conditions, the ratio of deep eutectic solvent to carbon nanotubes is 1:35. This ratio leads to unstable solidification of the deep eutectic solvent on the carbon nanotube carrier, and the desulfurization time requires 60 minutes. Patent CN 108579125 A discloses a method for desulfurization of dibenzothiophene by loading a ternary deep eutectic solvent onto carbon nanotubes. According to this patent, the amount of composite material needs to be four times that of the dibenzothiophene n-octane simulated oil system to achieve a desulfurization efficiency of 99.9%. While this condition ensures desulfurization efficiency, it suffers from the drawback of excessive composite material dosage, increasing the material cost and operational load of the desulfurization process. Patent CN 107384469 A discloses a method for desulfurization of dibenzothiophene by loading a deep eutectic solvent onto carbon nanotubes. A review of all the implementation cases documented in this patent reveals that achieving a 99.99% desulfurization efficiency requires harsh conditions such as high-temperature environments or long processing times, neither of which is conducive to the industrial-scale, low-cost desulfurization needs. Patent CN107541241 A proposes a benzothiophene extraction desulfurization technology based on MXene deep eutectic solvent composite materials. This patent shows that the synthesis cycle of its key carrier, the two-dimensional MXene material, is as long as 75 hours, resulting in high time costs. Furthermore, this patent does not disclose actual data on the removal efficiency of thiophene. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention provides a composite material for the extraction and removal of thiophene, its preparation method, and its application. This invention removes thiophene sulfides from fuel oil by loading a deep eutectic solvent onto phosphorus-doped carbon nitride, utilizing the extraction by the deep eutectic solvent and the adsorption by the phosphorus-doped carbon nitride. This invention employs a synergistic desulfurization process using extraction, oxidation, and adsorption. This method offers mild operating conditions, high desulfurization efficiency, and overcomes the inconvenience of transporting and storing deep eutectic solvents in industrial applications, achieving a thiophene removal efficiency approaching 99.9%.

[0005] The above-mentioned objective of this invention is achieved through the following technical solution: A composite material for extracting thiophene, wherein the composite material is a phosphorus-doped carbon nitride-supported deep eutectic solvent; the mass ratio of the deep eutectic solvent to the phosphorus-doped carbon nitride is 5-40:1.

[0006] The deep eutectic solvent includes a hydrogen bond acceptor and a hydrogen bond donor; the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1-3:1-3; the hydrogen bond acceptor is any one of tetramethylammonium chloride, tetraethylammonium chloride, tetrabutylammonium chloride, or choline chloride; the hydrogen bond donor is any one of p-toluenesulfonic acid, p-aminosalicylic acid, or 5-sulfosalicylic acid.

[0007] This invention also claims protection for a method for preparing the above-mentioned thiophene-extractable composite material, specifically comprising the following steps: S1. Preparation of phosphorus-doped carbon nitride: The preparation method is thermal polymerization. Dicyandiamide, ammonium chloride, and hydroxyethylidene diphosphonic acid are weighed, ground in a mortar, placed in a crucible, calcined in air at 500℃-600℃ for 2-5 hours, and then washed, centrifuged, and dried to obtain phosphorus-doped carbon nitride. S2. To prepare a deep eutectic solvent, weigh hydrogen bond acceptor and hydrogen bond donor in molar ratio, place them in a round-bottom flask, and heat and stir in an oil bath at 60℃-140℃ for 3-5 hours to obtain a deep eutectic solvent; S3. Loading: 2-4g of the deep eutectic solvent prepared in step S2 and 0.1-1g of the phosphorus-doped carbon nitride prepared in step S1 are placed together in a round-bottom flask by impregnation and magnetically stirred at 60℃-140℃ for 3-6h to obtain the extraction desulfurization composite material.

[0008] Furthermore, in step S1, the weight ratio of dicyandiamide, ammonium chloride, and hydroxyethylidene diphosphonic acid is 5-30:1-10:0.1-1.

[0009] Furthermore, in step S1, the washing process involves using deionized water.

[0010] Furthermore, in step S1, the centrifugation conditions are 6000rpm-10000rpm for 5-20min.

[0011] Furthermore, in step S1, the drying conditions are 60℃-90℃ for 8h-12h.

[0012] This invention also seeks protection for the application of the composite material prepared by the above preparation method in the extraction and removal of thiophene.

[0013] The specific application method is as follows: stir and mix the thiophene n-octane solution, the composite material and the oxidant, and let them stand to separate into layers; wherein the mass ratio of the composite material, the thiophene n-octane solution and the oxidant is 0.1-0.5:0.3-1:0.01-0.1.

[0014] The concentration of the thiophene-n-octane solution is 1500ppm-1700ppm.

[0015] The mixing conditions are: magnetic stirring at 200-1000r for 10-60 minutes at 20-60℃.

[0016] The oxidant is any one of 30% hydrogen peroxide solution, cyclohexanone peroxide, or tert-butanol peroxide.

[0017] The beneficial effects of this invention compared to the prior art are: The present invention synthesizes phosphorus-doped carbon nitride raw materials through a one-step thermal polymerization method, which has low cost and high yield. Furthermore, it employs an impregnation method to load a deep eutectic solvent onto the phosphorus-doped carbon nitride and solidify the composite material, thereby overcoming the disadvantages of inconvenient industrial transportation and storage caused by the fact that the deep eutectic solvent is a liquid.

[0018] The composite material provided by this invention can efficiently remove thiophene sulfides from fuel in a short time. The extraction method is simple, the desulfurization efficiency is high, the operating conditions are mild, and the environment is friendly. The thiophene deep removal efficiency reaches 99.9%. Detailed Implementation

[0019] The present invention is described in detail below through specific embodiments, but this does not limit the scope of protection of the present invention. Unless otherwise specified, the experimental methods used in the present invention are all conventional methods, and the experimental equipment, materials, reagents, etc. used can all be obtained commercially.

[0020] Example 1 A method for preparing a composite material for extracting thiophene includes the following steps: Tetrabutylammonium chloride and p-toluenesulfonic acid are weighed at a molar ratio of 1:2 and magnetically stirred at 80°C for 4 hours to obtain 3g of a deep eutectic solvent; 10g of dicyandiamide, 5g of ammonium chloride, and 0.75g of hydroxyethylidene diphosphonic acid are weighed and ground in a mortar for 5 minutes to mix thoroughly. The mixture is then transferred to a crucible and placed in a muffle furnace, where it is calcined at 550°C for 3 hours in air. After cooling, the resulting powder is washed with deionized water and centrifuged at 7000 rpm for 10 minutes. This washing-centrifugation operation is repeated three times. Finally, the powder is dried in an oven at 80°C for 12 hours to obtain phosphorus-doped carbon nitride. The 3g deep eutectic solvent and 0.3g of phosphorus-doped carbon nitride are then magnetically stirred at 80°C for 4 hours using an impregnation method to obtain a loaded and cured composite material, which is convenient for transportation.

[0021] The above-mentioned composite material was used to extract thiophene. Specifically, 0.5 g of a 1600 ppm thiophene n-octane solution, 0.15 g of the composite material, and 0.05 g of a 30% hydrogen peroxide solution were stirred at 40°C and 800 rpm for 30 min. After standing and separating the layers, the concentration of thiophene in the n-octane layer was detected using a gas chromatograph, and the desulfurization rate of thiophene was calculated to be 90.61%. Example 2 A method for preparing a composite material for extracting thiophene includes the following steps: Tetraethylammonium chloride and p-toluenesulfonic acid are weighed at a molar ratio of 1:2 and magnetically stirred at 80°C for 4 hours to obtain 3g of a deep eutectic solvent; 10g of dicyandiamide, 5g of ammonium chloride, and 0.75g of hydroxyethylidene diphosphonic acid are weighed and ground in a mortar for 5 minutes to mix thoroughly. The mixture is then transferred to a crucible and placed in a muffle furnace, where it is calcined at 550°C for 3 hours in air. After cooling, the resulting powder is washed with deionized water and centrifuged at 7000 rpm for 10 minutes. This washing-centrifugation operation is repeated three times. Finally, the powder is dried in an oven at 80°C for 12 hours to obtain phosphorus-doped carbon nitride. The 3g deep eutectic solvent and 0.3g of phosphorus-doped carbon nitride are then magnetically stirred at 80°C for 4 hours using an impregnation method to obtain a loaded and cured composite material, which is convenient for transportation.

[0022] The above composite material was used to extract thiophene. Specifically, 0.5 g of thiophene n-octane solution with a concentration of 1600 ppm, 0.15 g of the composite material and 0.05 g of 30% hydrogen peroxide solution were stirred at 800 rpm for 30 min at 40 °C. After standing and separating into layers, the concentration of thiophene in the n-octane layer was detected by gas chromatography, and the desulfurization rate of thiophene was calculated to be 85.85%.

[0023] Example 3 A method for preparing a composite material for extracting thiophene includes the following steps: Tetramethylammonium chloride and p-toluenesulfonic acid are weighed at a molar ratio of 1:2 and magnetically stirred at 80°C for 4 hours to obtain 3g of a deep eutectic solvent; 10g of dicyandiamide, 5g of ammonium chloride, and 0.75g of hydroxyethylidene diphosphonic acid are weighed and ground in a mortar for 5 minutes to mix thoroughly. The mixture is then transferred to a crucible and placed in a muffle furnace, where it is calcined at 550°C for 3 hours in air. After cooling, the resulting powder is washed with deionized water and centrifuged at 7000 rpm for 10 minutes. This washing-centrifugation operation is repeated three times. Finally, the powder is dried in an oven at 80°C for 12 hours to obtain phosphorus-doped carbon nitride. The 3g deep eutectic solvent and 0.3g of phosphorus-doped carbon nitride are then magnetically stirred at 80°C for 4 hours using an impregnation method to obtain a loaded and cured composite material, which is convenient for transportation.

[0024] The above composite material was used to extract thiophene. Specifically, 0.5 g of thiophene n-octane solution with a concentration of 1600 ppm, 0.15 g of the composite material and 0.05 g of 30% hydrogen peroxide solution were stirred at 800 rpm for 30 min at 40 °C. After standing and separating into layers, the concentration of thiophene in the n-octane layer was detected by gas chromatography, and the desulfurization rate of thiophene was calculated to be 85.23%.

[0025] Example 4 A method for preparing a composite material for extracting thiophene includes the following steps: Choline chloride and p-toluenesulfonic acid are weighed at a molar ratio of 1:2 and magnetically stirred at 80°C for 4 hours to obtain 3g of a deep eutectic solvent; 10g of dicyandiamide, 5g of ammonium chloride, and 0.75g of hydroxyethylidene diphosphonic acid are weighed and ground in a mortar for 5 minutes to mix thoroughly. The mixture is then transferred to a crucible and placed in a muffle furnace, where it is calcined at 550°C for 3 hours in air. After cooling, the resulting powder is washed with deionized water and centrifuged at 7000 rpm for 10 minutes. This washing-centrifugation operation is repeated three times. Finally, the powder is dried in an oven at 80°C for 12 hours to obtain phosphorus-doped carbon nitride. The 3g deep eutectic solvent and 0.3g of phosphorus-doped carbon nitride are then magnetically stirred at 80°C for 4 hours using an impregnation method to obtain a loaded and cured composite material.

[0026] The above composite material was used to extract thiophene. Specifically, 0.5 g of thiophene n-octane solution with a concentration of 1600 ppm, 0.15 g of the composite material and 0.05 g of 30% hydrogen peroxide solution were stirred at 800 rpm for 30 min at 40 °C. After standing and separating into layers, the concentration of thiophene in the n-octane layer was detected by a gas chromatograph, and the desulfurization rate of thiophene was calculated to be 87.78%.

[0027] Example 5 A method for preparing a composite material for extracting thiophene includes the following steps: Tetrabutylammonium chloride and p-toluenesulfonic acid are weighed at a molar ratio of 1:2 and magnetically stirred at 80°C for 4 hours to obtain 3g of a deep eutectic solvent; 10g of dicyandiamide, 5g of ammonium chloride, and 0.75g of hydroxyethylidene diphosphonic acid are weighed and ground in a mortar for 5 minutes to mix thoroughly. The mixture is then transferred to a crucible and placed in a muffle furnace, where it is calcined at 550°C for 3 hours in air. After cooling, the resulting powder is washed with deionized water and centrifuged at 7000 rpm for 10 minutes. This washing-centrifugation operation is repeated three times. Finally, the powder is dried in an oven at 80°C for 12 hours to obtain phosphorus-doped carbon nitride. The 3g deep eutectic solvent and 0.3g of phosphorus-doped carbon nitride are then magnetically stirred at 80°C for 4 hours using an impregnation method to obtain a loaded and cured composite material, which is convenient for transportation.

[0028] The above composite material was used to extract thiophene. Specifically, 0.5 g of thiophene n-octane solution with a concentration of 1600 ppm, 0.25 g of the composite material and 0.05 g of 30% hydrogen peroxide solution were stirred at 1000 rpm for 40 min at 40 °C. After standing and separating into layers, the concentration of thiophene in the n-octane layer was detected by gas chromatography, and the desulfurization rate of thiophene was calculated to be 96.87%.

[0029] Example 6 A method for preparing a composite material for extracting thiophene includes the following steps: Tetraethylammonium chloride and p-toluenesulfonic acid are weighed at a molar ratio of 1:2 and magnetically stirred at 80°C for 4 hours to obtain 3g of a deep eutectic solvent; 10g of dicyandiamide, 5g of ammonium chloride, and 0.75g of hydroxyethylidene diphosphonic acid are weighed and ground in a mortar for 5 minutes to mix thoroughly. The mixture is then transferred to a crucible and placed in a muffle furnace, where it is calcined at 550°C for 3 hours in air. After cooling, the resulting powder is washed with deionized water and centrifuged at 7000 rpm for 10 minutes. This washing-centrifugation operation is repeated three times. Finally, the powder is dried in an oven at 80°C for 12 hours to obtain phosphorus-doped carbon nitride. The 3g deep eutectic solvent and 0.3g of phosphorus-doped carbon nitride are then magnetically stirred at 80°C for 4 hours using an impregnation method to obtain a loaded and cured composite material, which is convenient for transportation.

[0030] The above composite material was used to extract thiophene. Specifically, 0.5 g of thiophene n-octane solution with a concentration of 1600 ppm, 0.25 g of the composite material and 0.05 g of 30% hydrogen peroxide solution were stirred at 800 rpm for 30 min at 40 °C. After standing and separating into layers, the concentration of thiophene in the n-octane layer was detected by gas chromatography, and the desulfurization rate of thiophene was calculated to be 97.05%.

[0031] Example 7 A method for preparing a composite material for extracting thiophene includes the following steps: Tetraethylammonium chloride and p-toluenesulfonic acid are weighed at a molar ratio of 1:2 and magnetically stirred at 80°C for 4 hours to obtain 3g of a deep eutectic solvent; 10g of dicyandiamide, 5g of ammonium chloride, and 0.75g of hydroxyethylidene diphosphonic acid are weighed and ground in a mortar for 5 minutes to mix thoroughly. The mixture is then transferred to a crucible and placed in a muffle furnace, where it is calcined at 550°C for 3 hours in air. After cooling, the resulting powder is washed with deionized water and centrifuged at 7000 rpm for 10 minutes. This washing-centrifugation operation is repeated three times. Finally, the powder is dried in an oven at 80°C for 12 hours to obtain phosphorus-doped carbon nitride. The 3g deep eutectic solvent and 0.3g of phosphorus-doped carbon nitride are then magnetically stirred at 80°C for 4 hours using an impregnation method to obtain a loaded and cured composite material, which is convenient for transportation.

[0032] The above composite material was used to extract thiophene. Specifically, 0.5 g of thiophene n-octane solution with a concentration of 1600 ppm, 0.25 g of the composite material and 0.03 g of 30% hydrogen peroxide solution were stirred at 800 rpm for 10 min at 40 °C. After standing and separating into layers, the concentration of thiophene in the n-octane layer was detected by gas chromatography, and the desulfurization rate of thiophene was calculated to be 88.93%.

[0033] Example 8 A method for preparing a composite material for extracting thiophene includes the following steps: Tetrabutylammonium chloride and p-toluenesulfonic acid are weighed at a molar ratio of 1:2 and magnetically stirred at 80°C for 4 hours to obtain 3g of a deep eutectic solvent; 10g of dicyandiamide, 5g of ammonium chloride, and 0.75g of hydroxyethylidene diphosphonic acid are weighed and ground in a mortar for 5 minutes to mix thoroughly. The mixture is then transferred to a crucible and placed in a muffle furnace, where it is calcined at 550°C for 3 hours in air. After cooling, the resulting powder is washed with deionized water and centrifuged at 7000 rpm for 10 minutes. This washing-centrifugation operation is repeated three times. Finally, the powder is dried in an oven at 80°C for 12 hours to obtain phosphorus-doped carbon nitride. The 3g deep eutectic solvent and 0.3g of phosphorus-doped carbon nitride are then magnetically stirred at 80°C for 4 hours using an impregnation method to obtain a loaded and cured composite material, which is convenient for transportation.

[0034] The above composite material was used to extract thiophene. Specifically, 0.5 g of thiophene n-octane solution with a concentration of 1600 ppm, 0.2 g of the composite material and 0.05 g of 30% hydrogen peroxide solution were stirred at 800 rpm for 30 min at 40 °C. After standing and separating into layers, the concentration of thiophene in the n-octane layer was detected by gas chromatography, and the desulfurization rate of thiophene was calculated to be 98.14%.

[0035] Example 9 A method for preparing a composite material for extracting thiophene includes the following steps: Tetrabutylammonium chloride and p-toluenesulfonic acid are weighed at a molar ratio of 1:2 and magnetically stirred at 80°C for 4 hours to obtain 3g of a deep eutectic solvent; 10g of dicyandiamide, 5g of ammonium chloride, and 0.75g of hydroxyethylidene diphosphonic acid are weighed and ground in a mortar for 5 minutes to mix thoroughly. The mixture is then transferred to a crucible and placed in a muffle furnace, where it is calcined at 550°C for 3 hours in air. After cooling, the resulting powder is washed with deionized water and centrifuged at 7000 rpm for 10 minutes. This washing-centrifugation operation is repeated three times. Finally, the powder is dried in an oven at 80°C for 12 hours to obtain phosphorus-doped carbon nitride. The 3g deep eutectic solvent and 0.3g of phosphorus-doped carbon nitride are then magnetically stirred at 80°C for 4 hours using an impregnation method to obtain a loaded and cured composite material, which is convenient for transportation.

[0036] The above composite material was used to extract thiophene. Specifically, 0.5 g of thiophene n-octane solution with a concentration of 1600 ppm, 0.25 g of the composite material and 0.05 g of 30% hydrogen peroxide solution were stirred at 800 rpm for 30 min at 40 °C. After standing and separating into layers, the concentration of thiophene in the n-octane layer was detected by gas chromatography, and the desulfurization rate of thiophene was calculated to be 98.99%.

[0037] Example 10 A method for preparing a composite material for extracting thiophene includes the following steps: Tetrabutylammonium chloride and p-toluenesulfonic acid are weighed at a molar ratio of 1:2 and magnetically stirred at 80°C for 4 hours to obtain 3g of a deep eutectic solvent; 10g of dicyandiamide, 5g of ammonium chloride, and 0.75g of hydroxyethylidene diphosphonic acid are weighed and ground in a mortar for 5 minutes to mix thoroughly. The mixture is then transferred to a crucible and placed in a muffle furnace, where it is calcined at 550°C for 3 hours in air. After cooling, the resulting powder is washed with deionized water and centrifuged at 7000 rpm for 10 minutes. This washing-centrifugation operation is repeated three times. Finally, the powder is dried in an oven at 80°C for 12 hours to obtain phosphorus-doped carbon nitride. The 3g deep eutectic solvent and 0.3g of phosphorus-doped carbon nitride are then magnetically stirred at 80°C for 4 hours using an impregnation method to obtain a loaded and cured composite material, which is convenient for transportation.

[0038] The above composite material was used to extract thiophene. Specifically, 0.5 g of a 1600 ppm thiophene n-octane solution, 0.25 g of the composite material, and 0.05 g of a 30% hydrogen peroxide solution were stirred at 1000 rpm for 30 min at 40 °C. After standing and separating into layers, the concentration of thiophene in the n-octane layer was detected by a gas chromatograph, and the desulfurization rate of thiophene was calculated to be 83.26%.

[0039] Example 11 A method for preparing a composite material for extracting thiophene includes the following steps: Tetrabutylammonium chloride and p-toluenesulfonic acid are weighed at a molar ratio of 1:2 and magnetically stirred at 80°C for 4 hours to obtain 3g of a deep eutectic solvent; 10g of dicyandiamide, 5g of ammonium chloride, and 0.75g of hydroxyethylidene diphosphonic acid are weighed and ground in a mortar for 5 minutes to mix thoroughly. The mixture is then transferred to a crucible and placed in a muffle furnace, where it is calcined at 550°C for 3 hours in air. After cooling, the resulting powder is washed with deionized water and centrifuged at 7000 rpm for 10 minutes. This washing-centrifugation operation is repeated three times. Finally, the powder is dried in an oven at 80°C for 12 hours to obtain phosphorus-doped carbon nitride. The 3g deep eutectic solvent and 0.3g of phosphorus-doped carbon nitride are then magnetically stirred at 80°C for 4 hours using an impregnation method to obtain a loaded and cured composite material, which is convenient for transportation.

[0040] The above composite material was used to extract thiophene. Specifically, 0.5 g of thiophene n-octane solution with a concentration of 1600 ppm, 0.25 g of the composite material and 0.05 g of 30% hydrogen peroxide solution were stirred at 800 rpm for 20 min at 40 °C. After standing and separating into layers, the concentration of thiophene in the n-octane layer was detected by gas chromatography, and the desulfurization rate of thiophene was calculated to be 96.80%.

[0041] Example 12 A method for preparing a composite material for extracting thiophene includes the following steps: Tetrabutylammonium chloride and p-toluenesulfonic acid are weighed at a molar ratio of 1:2 and magnetically stirred at 80°C for 4 hours to obtain 3g of a deep eutectic solvent; 10g of dicyandiamide, 5g of ammonium chloride, and 0.75g of hydroxyethylidene diphosphonic acid are weighed and ground in a mortar for 5 minutes to mix thoroughly. The mixture is then transferred to a crucible and placed in a muffle furnace, where it is calcined at 550°C for 3 hours in air. After cooling, the resulting powder is washed with deionized water and centrifuged at 7000 rpm for 10 minutes. This washing-centrifugation operation is repeated three times. Finally, the powder is dried in an oven at 80°C for 12 hours to obtain phosphorus-doped carbon nitride. The 3g deep eutectic solvent and 0.3g of phosphorus-doped carbon nitride are then magnetically stirred at 80°C for 4 hours using an impregnation method to obtain a loaded and cured composite material, which is convenient for transportation.

[0042] The above composite material was used to extract thiophene. Specifically, 0.5 g of thiophene n-octane solution with a concentration of 1600 ppm, 0.25 g of the composite material and 0.05 g of 30% hydrogen peroxide solution were stirred at 800 rpm for 50 min at 40 °C. After standing and separating into layers, the concentration of thiophene in the n-octane layer was detected by gas chromatography, and the desulfurization rate of thiophene was calculated to be 99.98%.

[0043] Example 13 A method for preparing a composite material for extracting thiophene includes the following steps: Choline chloride and p-toluenesulfonic acid are weighed at a molar ratio of 1:2 and magnetically stirred at 80°C for 4 hours to obtain 3g of a deep eutectic solvent; 10g of dicyandiamide, 5g of ammonium chloride, and 0.75g of hydroxyethylidene diphosphonic acid are weighed and ground in a mortar for 5 minutes to mix thoroughly. The mixture is then transferred to a crucible and placed in a muffle furnace, where it is calcined at 550°C for 3 hours in air. After cooling, the resulting powder is washed with deionized water and centrifuged at 7000 rpm for 10 minutes. This washing-centrifugation operation is repeated three times. Finally, the powder is dried in an oven at 80°C for 12 hours to obtain phosphorus-doped carbon nitride. The 3g deep eutectic solvent and 0.3g of phosphorus-doped carbon nitride are then magnetically stirred at 80°C for 4 hours using an impregnation method to obtain a loaded and cured composite material, which is convenient for transportation.

[0044] The above composite material was used to extract thiophene. Specifically, 0.5 g of thiophene n-octane solution with a concentration of 1600 ppm, 0.25 g of the composite material and 0.05 g of 30% hydrogen peroxide solution were stirred at 800 rpm for 50 min at 40 °C. After standing and separating into layers, the concentration of thiophene in the n-octane layer was detected by gas chromatography, and the desulfurization rate of thiophene was calculated to be 98.32%.

[0045] Example 14 A method for preparing a composite material for extracting thiophene includes the following steps: Tetrabutylammonium chloride and p-toluenesulfonic acid are weighed at a molar ratio of 1:2 and magnetically stirred at 80°C for 4 hours to obtain 3g of a deep eutectic solvent; 10g of dicyandiamide, 5g of ammonium chloride, and 0.75g of hydroxyethylidene diphosphonic acid are weighed and ground in a mortar for 5 minutes to mix thoroughly. The mixture is then transferred to a crucible and placed in a muffle furnace, where it is calcined at 550°C for 3 hours in air. After cooling, the resulting powder is washed with deionized water and centrifuged at 7000 rpm for 10 minutes. This washing-centrifugation operation is repeated three times. Finally, the powder is dried in an oven at 80°C for 12 hours to obtain phosphorus-doped carbon nitride. The 3g deep eutectic solvent and 0.3g of phosphorus-doped carbon nitride are then magnetically stirred at 80°C for 4 hours using an impregnation method to obtain a loaded and cured composite material, which is convenient for transportation.

[0046] The above composite material was used to extract thiophene. Specifically, 0.5 g of thiophene n-octane solution with a concentration of 1600 ppm, 0.25 g of the composite material and 0.05 g of 30% hydrogen peroxide solution were stirred at 800 rpm for 40 min at 40 °C. After standing and separating into layers, the concentration of thiophene in the n-octane layer was detected by a gas chromatograph, and the desulfurization rate of thiophene was calculated to be 99.9%.

[0047] Comparative Example 1 A method for preparing a composite material for extracting thiophene includes the following steps: Choline chloride and 5-sulfosalicylic acid are weighed at a molar ratio of 1:2 and magnetically stirred at 120°C for 4 hours to obtain 3g of a deep eutectic solvent; 10g of dicyandiamide, 5g of ammonium chloride, and 0.75g of hydroxyethylidene diphosphonic acid are weighed and ground in a mortar for 5 minutes to mix thoroughly. The mixture is then transferred to a crucible and placed in a muffle furnace, where it is calcined at 550°C for 3 hours in air. After cooling, the resulting powder is washed with deionized water and centrifuged at 7000 rpm for 10 minutes. This washing-centrifugation operation is repeated three times. Finally, the powder is dried in an oven at 80°C for 12 hours to obtain phosphorus-doped carbon nitride. The 3g deep eutectic solvent and 0.3g of phosphorus-doped carbon nitride are then magnetically stirred at 120°C for 4 hours using an impregnation method to obtain a loaded and cured composite material, which is convenient for transportation.

[0048] The above composite material was used to extract thiophene. Specifically, 0.5 g of thiophene n-octane solution with a concentration of 1600 ppm, 0.15 g of the composite material and 0.05 g of 30% hydrogen peroxide solution were stirred at 800 rpm for 30 min at 40 °C. After standing and separating into layers, the concentration of thiophene in the n-octane layer was detected by gas chromatography, and the desulfurization rate of thiophene was calculated to be 34.40%.

[0049] Comparative Example 2 A method for preparing a composite material for extracting thiophene includes the following steps: Choline chloride and para-aminosalicylic acid are weighed at a molar ratio of 1:2 and magnetically stirred at 130°C for 4 hours to obtain 3g of a deep eutectic solvent; 10g of dicyandiamide, 5g of ammonium chloride, and 0.75g of hydroxyethylidene diphosphonic acid are weighed and ground in a mortar for 5 minutes to mix thoroughly. The mixture is then transferred to a crucible and placed in a muffle furnace, where it is calcined at 550°C for 3 hours in air. After cooling, the resulting powder is washed with deionized water and centrifuged at 7000 rpm for 10 minutes. This washing-centrifugation operation is repeated three times. Finally, the powder is dried in an oven at 80°C for 12 hours to obtain phosphorus-doped carbon nitride. The 3g deep eutectic solvent and 0.3g of phosphorus-doped carbon nitride are then magnetically stirred at 130°C for 4 hours using an impregnation method to obtain a loaded and cured composite material, which is convenient for transportation.

[0050] The above composite material was used to extract thiophene. Specifically, 0.5 g of thiophene n-octane solution with a concentration of 1600 ppm, 0.15 g of the composite material and 0.05 g of 30% hydrogen peroxide solution were stirred at 800 rpm for 30 min at 40 °C. After standing and separating into layers, the concentration of thiophene in the n-octane layer was detected by gas chromatography, and the desulfurization rate of thiophene was calculated to be 44.28%.

[0051] Comparative Example 3 A method for preparing a composite material for extracting thiophene includes the following steps: Tetraethylammonium chloride and p-toluenesulfonic acid are weighed at a molar ratio of 1:2 and magnetically stirred at 80°C for 4 hours to obtain 3g of a deep eutectic solvent; 10g of dicyandiamide, 5g of ammonium chloride, and 0.75g of hydroxyethylidene diphosphonic acid are weighed and ground in a mortar for 5 minutes to mix thoroughly. The mixture is then transferred to a crucible and placed in a muffle furnace, where it is calcined at 550°C for 3 hours in air. After cooling, the resulting powder is washed with deionized water and centrifuged at 7000 rpm for 10 minutes. This washing-centrifugation operation is repeated three times. Finally, the powder is dried in an oven at 80°C for 12 hours to obtain phosphorus-doped carbon nitride. The 3g deep eutectic solvent and 0.3g of phosphorus-doped carbon nitride are then magnetically stirred at 80°C for 4 hours using an impregnation method to obtain a loaded and cured composite material, which is convenient for transportation.

[0052] The above composite material was used to extract thiophene. Specifically, 0.5 g of thiophene n-octane solution with a concentration of 1600 ppm, 0.25 g of the composite material and 0.05 g of tert-butanol peroxide solution were stirred at 800 rpm for 10 min at 40 °C. After standing and separating into layers, the concentration of thiophene in the n-octane layer was detected by gas chromatography, and the desulfurization rate of thiophene was calculated to be 67.46%.

[0053] Comparative Example 4 A method for preparing a composite material for extracting thiophene includes the following steps: Tetraethylammonium chloride and p-toluenesulfonic acid are weighed at a molar ratio of 1:2 and magnetically stirred at 80°C for 4 hours to obtain 3g of a deep eutectic solvent; 10g of dicyandiamide, 5g of ammonium chloride, and 0.75g of hydroxyethylidene diphosphonic acid are weighed and ground in a mortar for 5 minutes to mix thoroughly. The mixture is then transferred to a crucible and placed in a muffle furnace, where it is calcined at 550°C for 3 hours in air. After cooling, the resulting powder is washed with deionized water and centrifuged at 7000 rpm for 10 minutes. This washing-centrifugation operation is repeated three times. Finally, the powder is dried in an oven at 80°C for 12 hours to obtain phosphorus-doped carbon nitride. The 3g deep eutectic solvent and 0.3g of phosphorus-doped carbon nitride are then magnetically stirred at 80°C for 4 hours using an impregnation method to obtain a loaded and cured composite material, which is convenient for transportation.

[0054] The above composite material was used to extract thiophene. Specifically, 0.5 g of thiophene n-octane solution with a concentration of 1600 ppm, 0.25 g of the composite material and 0.05 g of cyclohexanone peroxide solution were stirred at 800 rpm for 10 min at 40 °C. After standing and separating into layers, the concentration of thiophene in the n-octane layer was detected by gas chromatography, and the desulfurization rate of thiophene was calculated to be 56.07%.

[0055] Comparative Example 5 A method for preparing a composite material for extracting thiophene includes the following steps: Tetrabutylammonium chloride and p-toluenesulfonic acid are weighed at a molar ratio of 1:2 and magnetically stirred at 80°C for 4 hours to obtain 3g of a deep eutectic solvent; 10g of dicyandiamide, 5g of ammonium chloride, and 0.75g of hydroxyethylidene diphosphonic acid are weighed and ground in a mortar for 5 minutes to mix thoroughly. The mixture is then transferred to a crucible and placed in a muffle furnace, where it is calcined at 550°C for 3 hours in air. After cooling, the resulting powder is washed with deionized water and centrifuged at 7000 rpm for 10 minutes. This washing-centrifugation operation is repeated three times. Finally, the powder is dried in an oven at 80°C for 12 hours to obtain phosphorus-doped carbon nitride. The 3g deep eutectic solvent and 0.15g of phosphorus-doped carbon nitride are then magnetically stirred at 80°C for 4 hours using an impregnation method to obtain a loaded and cured composite material, which is convenient for transportation.

[0056] The above composite material was used to extract thiophene. Specifically, 0.5 g of thiophene n-octane solution with a concentration of 1600 ppm, 0.15 g of the composite material and 0.05 g of 30% hydrogen peroxide solution were stirred at 800 rpm for 20 min at 40 °C. After standing and separating into layers, the concentration of thiophene in the n-octane layer was detected by gas chromatography, and the desulfurization rate of thiophene was calculated to be 60.42%.

[0057] Comparative Example 6 A method for preparing a composite material for extracting thiophene includes the following steps: Tetrabutylammonium chloride and p-toluenesulfonic acid are weighed at a molar ratio of 1:2 and magnetically stirred at 80°C for 4 hours to obtain 3g of a deep eutectic solvent; 10g of dicyandiamide, 5g of ammonium chloride, and 0.75g of hydroxyethylidene diphosphonic acid are weighed and ground in a mortar for 5 minutes to mix thoroughly. The mixture is then transferred to a crucible and placed in a muffle furnace, where it is calcined at 550°C for 3 hours in air. After cooling, the resulting powder is washed with deionized water and centrifuged at 7000 rpm for 10 minutes. This washing-centrifugation operation is repeated three times. Finally, the powder is dried in an oven at 80°C for 12 hours to obtain phosphorus-doped carbon nitride. The 3g deep eutectic solvent and 0.3g of phosphorus-doped carbon nitride are then magnetically stirred at 80°C for 4 hours using an impregnation method to obtain a loaded and cured composite material, which is convenient for transportation.

[0058] The above composite material was used to extract thiophene. Specifically, 0.5 g of thiophene n-octane solution with a concentration of 1600 ppm, 0.15 g of the composite material and 0.05 g of 30% hydrogen peroxide solution were stirred at 800 rpm for 20 min at 40 °C. After standing and separating into layers, the concentration of thiophene in the n-octane layer was detected by gas chromatography, and the desulfurization rate of thiophene was calculated to be 57.79%.

[0059] Comparative Example 7 A method for preparing a composite material for extracting thiophene includes the following steps: Tetrabutylammonium chloride and p-toluenesulfonic acid are weighed at a molar ratio of 1:2 and magnetically stirred at 80°C for 4 hours to obtain 3g of a deep eutectic solvent; 10g of dicyandiamide, 5g of ammonium chloride, and 0.75g of hydroxyethylidene diphosphonic acid are weighed and ground in a mortar for 5 minutes to mix thoroughly. The mixture is then transferred to a crucible and placed in a muffle furnace, where it is calcined at 550°C for 3 hours in air. After cooling, the resulting powder is washed with deionized water and centrifuged at 7000 rpm for 10 minutes. This washing-centrifugation operation is repeated three times. Finally, the powder is dried in an oven at 80°C for 12 hours to obtain phosphorus-doped carbon nitride. The 3g deep eutectic solvent and 0.3g of phosphorus-doped carbon nitride are then magnetically stirred at 80°C for 4 hours using an impregnation method to obtain a loaded and cured composite material, which is convenient for transportation.

[0060] The above composite material was used to extract thiophene. Specifically, 0.5 g of thiophene n-octane solution with a concentration of 1600 ppm, 0.25 g of the composite material and 0.05 g of 30% hydrogen peroxide solution were stirred at 400 rpm for 30 min at 40 °C. After standing and separating into layers, the concentration of thiophene in the n-octane layer was detected by gas chromatography, and the desulfurization rate of thiophene was calculated to be 50.89%.

[0061] Comparative Example 8 A method for preparing a composite material for extracting thiophene includes the following steps: Tetraethylammonium chloride and p-toluenesulfonic acid are weighed at a molar ratio of 1:2 and magnetically stirred at 80°C for 4 hours to obtain 3g of a deep eutectic solvent; 10g of dicyandiamide is weighed, ground in a mortar for 5 minutes to mix, transferred to a crucible, and placed in a muffle furnace. The mixture is calcined at 550°C for 3 hours in air atmosphere. After cooling, the resulting powder is washed with deionized water and centrifuged at 7000 rpm for 10 minutes. This washing-centrifugation operation is repeated three times. Finally, the powder is dried in an oven at 80°C for 12 hours to obtain carbon nitride. The 3g deep eutectic solvent and 0.3g carbon nitride are then magnetically stirred at 80°C for 4 hours using an impregnation method to obtain a loaded and cured composite material, which is convenient for transportation.

[0062] The above composite material was used to extract thiophene. Specifically, 0.5 g of thiophene n-octane solution with a concentration of 1600 ppm, 0.15 g of the composite material and 0.05 g of 30% hydrogen peroxide solution were stirred at 800 rpm for 20 min at 40 °C. After standing and separating into layers, the concentration of thiophene in the n-octane layer was detected by gas chromatography, and the desulfurization rate of thiophene was calculated to be 62.85%.

[0063] Comparative Example 9 A method for preparing a composite material for extracting thiophene includes the following steps: Tetrabutylammonium chloride and p-toluenesulfonic acid are weighed at a molar ratio of 1:2 and magnetically stirred at 80°C for 4 hours to obtain 3g of a deep eutectic solvent; 10g of dicyandiamide, 5g of ammonium chloride, and 0.75g of hydroxyethylidene diphosphonic acid are weighed and ground in a mortar for 5 minutes to mix thoroughly. The mixture is then transferred to a crucible and placed in a muffle furnace, where it is calcined at 550°C for 3 hours in air. After cooling, the resulting powder is washed with deionized water and centrifuged at 7000 rpm for 10 minutes. This washing-centrifugation operation is repeated three times. Finally, the powder is dried in an oven at 80°C for 12 hours to obtain phosphorus-doped carbon nitride. The 3g deep eutectic solvent and 0.1g of phosphorus-doped carbon nitride are then magnetically stirred at 80°C for 4 hours using an impregnation method to obtain a loaded and cured composite material, which is convenient for transportation.

[0064] The above composite material was used to extract thiophene. Specifically, 0.5 g of thiophene n-octane solution with a concentration of 1600 ppm, 0.15 g of the composite material and 0.05 g of 30% hydrogen peroxide solution were stirred at 800 rpm for 20 min at 40 °C. After standing and separating into layers, the concentration of thiophene in the n-octane layer was detected by gas chromatography, and the desulfurization rate of thiophene was calculated to be 47.43%.

[0065] Comparative Example 10 Application Example 6 of Patent CN 110922386 A represents the optimal case for thiophene removal, achieving a desulfurization rate of 96.01%. In this case, 3.5g of a deep eutectic solvent was prepared using choline chloride and p-toluenesulfonic acid in a 1:2 molar ratio. This solvent was then loaded onto 0.1g of carbon nanotubes, and the desulfurization reaction was completed in 60 minutes, achieving the aforementioned effect. However, a carbon nanotube to deep eutectic solvent loading ratio of 1:35 makes it difficult to ensure stable curing of the composite material, and the 60-minute processing time results in a relatively long desulfurization cycle.

[0066] Comparative Example 11 Patent CN 120137694 A uses a hydrothermal method to prepare graphitic carbon nitride@graphene oxide nanospheres, but suffers from low yield, making it difficult to meet the demands of industrial mass production. In Example 3, 3g of a deep eutectic solvent was prepared using tetrabutylammonium chloride and p-toluenesulfonic acid in a 1:2 molar ratio. This solvent was then loaded onto 0.1g of the aforementioned nanospheres, resulting in a loading ratio of 1:30. The desulfurization efficiency of the resulting composite material was 82.93%, which is not ideal.

[0067] Comparative Example 12 In Example 3 of patent CN 108579125 A, which describes the optimal desulfurization efficiency of extracting dibenzothiophene by loading a ternary deep eutectic solvent onto carbon nanotubes, it is shown that when the amount of composite material is four times the mass of the dibenzothiophene n-octane simulated oil system, the desulfurization efficiency of the system can reach 99.9%. However, this composite material addition ratio will significantly increase the cost of process raw materials, which is not conducive to large-scale industrial application.

[0068] Comparative Example 13 Patent CN 107541241 A proposes a benzothiophene extraction desulfurization technology based on MXene / deep eutectic solvent composite material. According to the implementation scheme described in this patent, the preparation of its core component, the two-dimensional MXene material, takes up to 75 hours, and the long preparation cycle significantly increases the time cost of the process; however, in terms of application effect, the technical solution of Example 1 can achieve a better desulfurization efficiency.

[0069] Comparative Example 14 Patent CN 107384469 A discloses a technical solution for the desulfurization of dibenzothiophene by using carbon nanotube-supported deep eutectic solvent composite materials. Examples 1 and 2 of this patent both achieve an optimal desulfurization efficiency of 99.99%, but achieving this high efficiency requires an extraction time of 60 minutes, resulting in a relatively high time cost.

[0070] In summary, Example 14 is the optimal embodiment of this patent. The example uses a thermal polymerization method to prepare phosphorus-doped carbon nitride, achieving a high synthesis yield and effectively overcoming the low yield defect of the method described in patent CN 120137694 A, demonstrating potential for industrial mass production. An extraction desulfurization composite material is prepared by mixing phosphorus-doped carbon nitride with a deep eutectic solvent at a loading ratio of 1:10. Compared to the comparative example, this material exhibits superior curing performance, facilitating storage and transportation. Furthermore, the desulfurization efficiency reaches 99.9% within 40 minutes, reducing process time and costs.

[0071] The embodiments described above are merely preferred embodiments of the present invention, and not all feasible embodiments of the present invention. Any obvious modifications made by those skilled in the art without departing from the principles and spirit of the present invention should be considered to be included within the scope of protection of the claims of the present invention.

Claims

1. A composite material for extracting thiophene, characterized in that, The composite material is a deep eutectic solvent loaded with phosphorus-doped carbon nitride; the mass ratio of the deep eutectic solvent to the phosphorus-doped carbon nitride is 5-40:

1.

2. The composite material for extracting thiophene according to claim 1, wherein The deep eutectic solvent comprises a hydrogen bond acceptor and a hydrogen bond donor; the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1-3:1-3; the hydrogen bond acceptor is any one of tetramethylammonium chloride, tetraethylammonium chloride, tetrabutylammonium chloride or choline chloride; and the hydrogen bond donor is any one of p-toluenesulfonic acid, p-aminosalicylic acid or 5-sulfosalicylic acid.

3. The method for preparing a composite material for extracting thiophene as described in claim 2, characterized in that, Specifically comprising the following steps: S1. Preparing phosphorus-doped carbon nitride, using a thermal polymerization method, weighing dicyandiamide, ammonium chloride and hydroxyethylidene diphosphonic acid, grinding in a mortar, placing in a crucible, calcining in air at 500-600 DEG C for 2-5 hours, then washing, centrifuging and drying to obtain phosphorus-doped carbon nitride; S2. Preparing a deep eutectic solvent, weighing a hydrogen bond acceptor and a hydrogen bond donor according to a molar ratio, and placing them in a round-bottom flask and heating and stirring in an oil bath at 60-140 DEG C for 3-5 hours to obtain a deep eutectic solvent; S3. Loading, placing 2-4 g of the deep eutectic solvent prepared in step S2 and 0.1-1 g of the phosphorus-doped carbon nitride prepared in step S1 in a round-bottom flask by the impregnation method, and magnetically stirring at 60-140 DEG C for 3-6 hours to obtain an extraction desulfurization composite material.

4. The method for preparing a composite material for extracting thiophene as described in claim 3, characterized in that, In step S1, the weight ratio of dicyandiamide, ammonium chloride and hydroxyethylidene diphosphonic acid is 5-30:1-10:0.1-1.

5. The method for preparing a composite material for extracting thiophene as described in claim 3, characterized in that, In step S1, the drying condition is 60-90 DEG C for 8-12 hours.

6. The application of the composite material prepared by the preparation method of the extraction thiophene composite material according to any one of claims 3-5 in the extraction removal of thiophene.

7. The use according to claim 6, wherein the compound is ###0002### The application specifically comprises: stirring and uniformly mixing a thiophene n-octane solution, a composite material and an oxidizing agent, and allowing them to separate into layers; The mass ratio of the composite material, the thiophene n-octane solution and the oxidizing agent is 0.1-0.5:0.3-1:0.01-0.

1.

8. Use according to claim 7, wherein the compound is ###0002### The concentration of the thiophene n-octane solution is 1500-1700 ppm.

9. The use according to claim 7, wherein the compound is ###0002### The stirring and uniform mixing condition is 200-1000 r of magnetic stirring at 20-60 DEG C for 10-60 min.

10. The use according to claim 7, wherein the compound is ###00003### 8 The oxidizing agent is any one of 30% hydrogen peroxide solution, peroxide cyclohexanone or tert-butyl hydroperoxide.