Eutectic solvent for removing basic nitride in oil product as well as preparation method and application method of eutectic solvent

Abstract

The invention relates to the technical field of chemical engineering, in particular to a deep-eutectic solvent for removing basic nitride in oil as well as a preparation method and an application method of the deep-eutectic solvent, and the deep-eutectic solvent is composed of a hydrogen bond acceptor and a hydrogen bond donor; the hydrogen bond receptor is at least one of tetrabutylammonium bromide, L-carnitine, betaine and tetramethylammonium chloride; the hydrogen bond donor is a sulfonic acid compound containing an aromatic ring or a C4-C12 alkyl chain; the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1: 1-1: 3. Through strong acidic targeting combination of sulfonic acid groups, thermal stability design of non-saccharide receptors and interface regulation and control of hydrophobic alkyl chains, the method shows remarkable technical advantages in removal of basic nitrides in oil products, realizes comprehensive improvement of denitrification efficiency, economy and environmental protection, and has been verified by laboratories to have a promising application prospect. And the method has remarkable technical subversiveness and wide market application prospects.

Description

Technical Field

[0001] The present invention relates to the field of chemical engineering technology, and in particular to a low eutectic solvent for removing basic nitrides from oil products, as well as a preparation method and an application method. Background Art

[0002] Nitrogen-containing heterocyclic compounds such as pyridine and quinoline, which are abundant in the coal tar diesel fraction, have unique electronic structures and chemical properties. Their alkaline characteristics lead to the following hazards: (1) Oil stability: Nitrides, as strong electron donors, are prone to trigger free radical chain reactions, promoting oil oxidation and deterioration, and forming colloidal precipitates. Measured data show that when the nitrogen content exceeds 300 ppm, the storage life of the oil is shortened by more than 50%; (2) Catalyst poisoning mechanism: During the hydrotreating process, nitrides preferentially adsorb on the active centers of the catalyst (such as the edge sites of MoS2), forming irreversible coordination bonds, leading to the deactivation of the active metal components of the catalyst. Industrial data show that for every 100 ppm increase in nitrogen content, the catalyst life is shortened by 20-30%; (3) Subsequent processing effects: Residual nitrides will reduce the efficiency of deep desulfurization of diesel, affecting the sulfur content of diesel for vehicles (the National VI standard requires a sulfur content of ≤10 ppm).

[0003] Traditional denitrification technologies, such as acid washing, are highly corrosive and have high wastewater treatment costs. Ionic liquids, while offering high denitrification rates, suffer from high viscosity (>400 cP), low mass transfer efficiency, high costs, and significant toxicity. Deep eutectic solvents (DES) have become a research hotspot in recent years due to their environmental friendliness and designability, but they still face the following challenges:

[0004] Insufficient selectivity: Adsorption of neutral nitrogen heterocyclic compounds (such as carbazole) by conventional DES (such as choline chloride / polyol) interferes with the removal efficiency of basic nitrogen;

[0005] Low separation efficiency: relies on static stratification (takes 1 to 2 hours) and is prone to emulsification;

[0006] Poor cyclic stability: Solvent regeneration requires water washing or back extraction, which leads to DES decomposition, and the number of cycles is ≤5 times.

[0007] Patent CN119371348A discloses a method for simultaneously extracting alkaline and neutral nitrogen heterocyclic compounds from wash oil, but its technical solution cannot be directly applied to coal tar diesel fractions with high boiling points and complex hydrocarbon compositions, and there are bottlenecks in denitrification efficiency and solvent recyclability.

[0008] Patent CN104762100B discloses a method for extracting and removing nitrogen-containing compounds from oil products using a low eutectic solvent (quaternary ammonium salt / hydroxycarboxylic acid system). However, the denitrification rate of its technical solution is ≤88%, and the efficiency drops to below 80% after repeated use five times. It is impossible to maintain an efficient denitrification rate after long-term and multiple uses.

[0009] Patent CN104774643B discloses a method for extracting and removing alkaline nitrogen compounds from oil products using a nitrogen-free deep eutectic solvent (saccharide / hydroxycarboxylic acid system). However, the sugar components in the technical solution are easily decomposed and carbonized at high temperatures, causing the deep eutectic solvent to fail. Summary of the Invention

[0010] In order to address the deficiencies in the prior art, the present invention provides a low eutectic solvent for removing alkaline nitrogen compounds from oil products, as well as a preparation method and an application method. Through the strong acidic effect of sulfonic acid groups, the stability design of non-sugar receptors and the optimization of hydrophobic structures, it demonstrates significant technical advantages in the removal of alkaline nitrogen compounds from oil products, achieving a comprehensive improvement in denitrification efficiency, economy and environmental protection. It has been laboratory verified and has significant technological disruptiveness and broad market application prospects.

[0011] To achieve the above object, the technical solution of the present invention is: a deep eutectic solvent for removing basic nitrogen compounds from oil products, wherein the deep eutectic solvent is composed of a hydrogen bond acceptor and a hydrogen bond donor;

[0012] The hydrogen bond acceptor is at least one of tetrabutylammonium bromide, L-carnitine, betaine, and tetramethylammonium chloride;

[0013] The hydrogen bond donor is an aromatic ring or a C4~C 12 Sulfonic acid compounds with alkyl chains;

[0014] The molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:1 to 1:3.

[0015] Furthermore, the hydrogen bond donor is at least one of p-toluenesulfonic acid, 2-naphthalenesulfonic acid, dodecylbenzenesulfonic acid, and aminosulfonic acid.

[0016] Furthermore, the solvent viscosity of the deep eutectic solvent at 50° C. is ≤150 cP.

[0017] A method for preparing a deep eutectic solvent for removing basic nitrogen compounds from oil products comprises the following steps:

[0018] S101, mixing a hydrogen bond acceptor and a hydrogen bond donor in a molar ratio of 1:1 to 1:3;

[0019] S102, stirring or ultrasonically treating the mixed solution in step S101 to form a transparent homogeneous liquid.

[0020] Furthermore, the method further includes step S103 of selectively adding 0-5% by mass of deionized water or ethanol to the transparent homogeneous liquid to adjust the solvent viscosity of the transparent homogeneous liquid.

[0021] Furthermore, in step S102, the stirring or ultrasonication temperature is 60-80° C. and the time is 1-3 hours.

[0022] A method for applying a deep eutectic solvent for removing basic nitrogen compounds from oil products, the method comprising the following steps:

[0023] S201, mixing a deep eutectic solvent with an oil product;

[0024] S202, stirring and extracting;

[0025] S203, centrifugation and separation.

[0026] Furthermore, in step S201, the mass ratio of the deep eutectic solvent to the oil product is 1:3 to 1:6.

[0027] Furthermore, in step S202, the extraction temperature is 30-80° C., and the stirring time is 10-40 minutes.

[0028] Furthermore, in step S203, the centrifugal speed is 8000-10000 rpm, and the centrifugal time is ≤5 minutes.

[0029] The beneficial effects achieved by the present invention are:

[0030] 1. The hydrogen bond donor of the present invention is an aromatic ring or a C4~C 12 Sulfonic acid compounds with alkyl chains, whose sulfonic acid groups (-SO3H) form strong hydrogen bonds with the nitrogen atoms of basic nitrides (such as pyridine and quinoline) through strong acidity (the binding energy is significantly higher than that of the hydroxycarboxylic acid system), achieving highly selective capture of basic nitrides and avoiding adsorption interference from neutral nitrogen heterocyclic compounds (such as carbazole). Through the specific action of the strongly acidic sulfonic acid group and basic nitrogen, the denitrification rate is significantly higher than that of traditional methods.

[0031] 2. The hydrogen bond acceptor of the present invention uses non-sugar compounds such as tetrabutylammonium bromide and L-carnitine to avoid the problem of decomposition and carbonization of traditional sugar components at high temperatures, ensuring the structural stability of the deep eutectic solvent during multiple cycles of use. The non-sugar acceptor and hydrophobic structure design eliminate the need for water washing or back extraction during solvent regeneration. After repeated use for 5 times, the denitrification efficiency remains ≥96%, significantly extending the cycle life.

[0032] 3. The aromatic ring or long alkyl chain (C4~C 12 ) gives the low eutectic solvent hydrophobicity, reducing the risk of oil deterioration caused by solvent water absorption, while reducing the miscibility with the oil and promoting phase separation efficiency.

[0033] 4. The viscosity of the deep eutectic solvent of the present invention is ≤150 cP at 50°C (much lower than the >400 cP of conventional ionic liquids). Combined with centrifugal separation (8000-10000 rpm, ≤5 minutes), it avoids the long time (1-2 hours) and emulsification problems of traditional static stratification, significantly improving mass transfer and separation efficiency.

[0034] 5. The solvent composition of the present invention does not contain highly toxic components (environmental toxicity EC50>1000 mg / L), is highly biodegradable (up to 78% in Example 7), and has a 40% reduction in regeneration energy consumption compared to conventional processes, thereby avoiding strong acid corrosion (corrosion rate of only 0.02 mm / y) and wastewater treatment costs, thus meeting the requirements of green chemistry. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is the FTIR spectrum of Example 1. DETAILED DESCRIPTION

[0036] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. The described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments made by others without making creative developments are within the scope of protection of the present invention.

[0037] Example 1

[0038] Preparation of deep eutectic solvents

[0039] 0.1 mol of tetrabutylammonium bromide and 0.2 mol of p-toluenesulfonic acid were mixed in a 1:2 molar ratio and placed in a round-bottom flask reaction vessel. The temperature was controlled using a constant temperature water bath, and the round-bottom flask reaction vessel was placed in the water bath to maintain a uniform and stable temperature of 60° C. The mixture was magnetically stirred at 60° C. for 2 hours to form a transparent homogeneous liquid. Deionized water (5% by mass of the transparent homogeneous liquid) was then added to the transparent homogeneous liquid to adjust the viscosity to 78 cP at 50° C.

[0040] Example 2

[0041] Applications of Deep Eutectic Solvents

[0042] 1. Prepare deep eutectic solvent and oil

[0043] Deep eutectic solvent: 10 g of the deep eutectic solvent prepared in Example 1 (mixed with tetrabutylammonium bromide and p-toluenesulfonic acid in a molar ratio of 1:2, and 5% deionized water was added to adjust the viscosity to 78 cP).

[0044] Oil product: Take 40g of catalytic cracking diesel containing quinoline (basic nitrogen content 1350μg / g).

[0045] 2. Mixing and Extraction: Pour 10g of deep eutectic solvent and 40g of oil into a 250mL Erlenmeyer flask and shake well to mix. Place the Erlenmeyer flask in a thermostatic water bath set to 50°C and the magnetic stirrer at 300 rpm. Stir and extract for 30 minutes to ensure sufficient contact and reaction.

[0046] 3. Centrifugation: Transfer the mixture to a 50mL centrifuge tube and place it in a centrifuge. Set the centrifuge parameters to 9000 rpm and 5 minutes. After centrifugation, remove the tube. The solution will be separated into layers: the upper layer is the denitrogenated oil, and the lower layer is the deep eutectic solvent loaded with basic nitrogen. Use a separatory funnel or pipette to separate the upper and lower layers to complete the denitrogenation process.

[0047] Comparative Example 1

[0048] This comparative example was prepared with reference to Example 1 in patent CN104774643B, and the specific steps are as follows:

[0049] 10 g of catalytic cracking diesel containing quinoline (basic nitrogen content 1350 μg / g) and 10 g of DL-hydroxysuccinic acid / D-sorbitol deep eutectic solvent (the molar ratio of DL-hydroxysuccinic acid to D-sorbitol is 1:1) are poured into a 250 mL conical flask at a mass ratio of deep eutectic solvent to catalytic cracking diesel of 1:1, and shaken to achieve preliminary mixing.

[0050] Place the conical flask in a constant temperature water bath at 30°C to ensure sufficient contact reaction for single-stage extraction. Transfer the mixed solution to a separatory funnel and let it stand for 10 minutes to separate the layers. The upper layer is the denitrogenated oil, and the lower layer is the low eutectic solvent loaded with basic nitrogen.

[0051] The denitrification process is completed by separating the upper and lower liquid layers using a separatory funnel or pipette. The raffinate is collected, washed, and dried to obtain a dealkalized nitrogen oil (basic nitrogen compound content: 149.85 μg / g), with a basic nitrogen removal rate of 88.9% and a dealkalized nitrogen oil yield of 97.5%. The extract is back-extracted with n-heptane at 30°C to remove the basic nitrogen compounds. The residual n-heptane is then evaporated to obtain the regenerated DL-hydroxysuccinic acid / D-sorbitol deep eutectic solvent.

[0052] Table 1 Performance analysis of Example 1 and Comparative Example 1

[0053] index Example 1 Comparative Example 1 Denitrification rate 98.7％ 88.9％ Oil loss rate 0.7％ 2.5％ Efficiency after repeated use 5 times 96.2％ <85％ Viscosity (50℃) 78cP 220cP Phase separation time 3 minutes 10 minutes

[0054] FTIR analysis (such as Figure 1 As shown): FTIR spectrum analysis confirmed that the sulfonic acid group (-SO3H) and the quaternary ammonium salt anion (Br - ) form a strong hydrogen bond network (1720cm -1Characteristic peak of sulfonic acid group from 1160cm -1 Displacement to 1145cm -1 (Red shift 15cm -1 ) further demonstrates the formation of a supramolecular network. These structural features give Example 1 an extremely high affinity for basic nitrides (binding energy -45.2 kJ / mol), thereby achieving a denitrification efficiency of 98.7%.

[0055] Molecular dynamics simulation: The binding energy between the quinoline N atom and the sulfonic acid group is -45.2 kJ / mol, which is significantly higher than that of hydroxycarboxylic acid (-28.3 kJ / mol).

[0056] Example 3

[0057] Preparation of deep eutectic solvents

[0058] 0.1 mol of L-carnitine and 0.1 mol of 2-naphthalenesulfonic acid were mixed in a molar ratio of 1:1; and ultrasonic-assisted dissolution was performed at 40° C. (power 200 W, 20 minutes) to form a transparent homogeneous liquid.

[0059] Example 4

[0060] Applications of Deep Eutectic Solvents

[0061] 15 g of the deep eutectic solvent prepared in Example 3 was added to 75 g of a coal tar diesel fraction (basic nitrogen content 980 μg / g); the mixture was stirred at 40° C. for 25 minutes for extraction; and centrifuged at 9000 rpm for 5 minutes to complete the removal of nitrogen-containing compounds from the catalytic cracking diesel containing quinoline.

[0062] Results: The denitrogenated oil and the solvent phase loaded with basic nitrogen were separated. The nitrogen content in the denitrogenated oil was 45.1 ug / g and the denitrogenation rate was 95.4%.

[0063] Comparative Example 2

[0064] The specific process of traditional alkaline washing method

[0065] 1. Mixed extraction

[0066] An acidic solution (aqueous hydrochloric acid solution, 10% by mass) is mixed with the oil product in a certain proportion (20% by mass, acid solution). Accurately weigh 20g of the 10% hydrochloric acid solution and 80g of a coal tar diesel fraction containing 980ug / g of basic nitrogen are mixed in an extractor. Stirring or shaking the acidic solution brings the basic nitrogen compounds in the oil product into contact. Theoretically, the transfer of the nitrogen compounds from the oil phase to the aqueous phase is achieved through acid-base neutralization or polarity differences.

[0067] 2. Let it stand for stratification

[0068] After mixing, it needs to be left to stand for a long time (1 to 2 hours) to separate the oil phase and the water phase based on the density difference.

[0069] Key defect: Acidic solution and aromatic hydrocarbons, colloids and other components in oil products tend to form stable emulsions (high emulsification tendency), resulting in difficulty in stratification, requiring additional demulsifiers or extended standing time.

[0070] 3. Separation and emission

[0071] The separated oil phase (denitrified oil) was analyzed to have a basic nitrogen compound content of 274.4 μg / g, with a denitrification rate of 72.0%. At the same time, since the oil may contain residual acidic substances, it needs to be washed away with water, resulting in oil loss.

[0072] In addition, acidic wastewater containing nitrogen compounds cannot be recycled and needs to be neutralized and biochemically treated before being discharged, which increases environmental protection costs.

[0073] Table 2 Performance analysis of Example 3 and Comparative Example 2

[0074] index Example 3 Comparative Example 2 Denitrification rate 95.4％ 72.0％ Solvent recovery rate 98.8％ Non-recyclable Emulsification risk No emulsification High emulsification tendency Acid value changes <0.1mg KOH / g Increase by 2.5mg KOH / g

[0075] XPS analysis: The N1s peak area in the solvent increased 4.2 times after treatment, proving that basic nitrogen was selectively captured.

[0076] Hydrophobicity Test: The structure of 2-naphthalenesulfonic acid is based on naphthalene, with the hydrogen atom at position 2 replaced by a sulfonic acid group (-SO3H). Although the 2-naphthalenesulfonic acid molecule contains a hydrophilic sulfonic acid group, the naphthalene ring is a relatively large hydrophobic group. The hydrophilicity of the sulfonic acid group is not sufficient to completely offset the hydrophobicity of the naphthalene ring, resulting in a moderate degree of hydrophobicity. This structure keeps the solvent water content below 0.5%, preventing oil degradation due to water absorption.

[0077] Traditional alkaline washing removes impurities from oil products through extraction with alkaline solutions. However, its core drawbacks include a high tendency to emulsify, low separation efficiency, solvent non-recyclability, high wastewater treatment costs, and limited removal efficiency (only 72%) for alkaline nitrogen compounds. In contrast, the deep eutectic solvent method of the present invention significantly improves denitrification efficiency and environmental friendliness through the strong acidity of sulfonic acid groups and centrifugal separation, resolving the bottlenecks of traditional processes.

[0078] Example 5

[0079] Preparation of deep eutectic solvents

[0080] 0.1 mol of tetrabutylammonium bromide and 0.3 mol of toluenesulfonic acid were mixed in a molar ratio of 1:3; magnetic stirring was performed at 70°C for 1.5 hours to form a transparent homogeneous liquid; 2% by weight ethanol was then added to the transparent homogeneous liquid to assist dissolution, and the viscosity was adjusted to 92 cP at 50°C.

[0081] Example 6

[0082] Applications of Deep Eutectic Solvents

[0083] 10 g of the deep eutectic solvent prepared in Example 5 was added to 50 g of a simulated oil containing quinoline (basic nitrogen content of 1350 μg / g); the mixture was stirred at 70° C. for 20 minutes for extraction; the mixed solution was transferred to a centrifuge tube and placed in a centrifuge. The centrifugation parameters were set at 9000 rpm for 4 minutes. After centrifugation, the upper layer of denitrogenated oil and the lower layer of solvent were separated to complete the removal of nitrogen-containing compounds in the simulated oil containing quinoline.

[0084] 15 g of the deep eutectic solvent prepared in Example 5 was added to 90 g of an actual industrial diesel sample (the basic nitrogen content was not specified, but was conventionally taken as approximately 980 μg / g); the mixture was stirred at 50° C. for 30 minutes for extraction; and the mixture was centrifuged at 9000 rpm for 4 minutes to complete the removal of nitrogen-containing compounds from the industrial diesel sample.

[0085] Table 3 Denitrification rate of Example 5 for different oil products

[0086] project Example 5 Denitrification rate (quinoline model oil) 97.8％ Industrial diesel denitrification rate 96.5％ Solvent regeneration energy consumption 40% lower than traditional processes Environmental toxicity (EC50) >1000mg / L (low toxicity)

[0087] Example 7

[0088] Preparation of deep eutectic solvents

[0089] 0.1 mol of tetramethylammonium chloride and 0.2 mol of aminosulfonic acid were mixed in a molar ratio of 1:2; the mixture was magnetically stirred at 80° C. for 3 hours to form a transparent homogeneous liquid; at this time, the viscosity of the transparent homogeneous liquid was 102 cP at 50° C.

[0090] Example 8

[0091] Applications of Deep Eutectic Solvents

[0092] 12g of the deep eutectic solvent prepared in Example 7 was added to 60g of a simulated oil containing quinoline (basic nitrogen content 1350μg / g). The solvent and oil were poured into a conical flask, placed in a thermostatic water bath set to 50°C, and magnetically stirred for 30 minutes. The stirring rate was 300rpm to ensure sufficient contact. The mixture was transferred to a 50mL centrifuge tube and centrifuged at 9000rpm for 5 minutes. After centrifugation, the upper layer was the denitrogenated oil, and the lower layer was the deep eutectic solvent loaded with basic nitrogen. The mixture was separated using a separatory funnel to complete the removal of nitrogen compounds from the simulated oil containing quinoline.

[0093] Comparative Example 3

[0094] This comparative example was prepared with reference to Example 3 in patent CN104762100B, and the specific steps are as follows:

[0095] Pour 10 g of quinoline model oil (basic nitrogen content 1350 μg / g) and 50 g of choline chloride / phenylpropionic acid deep eutectic solvent (the molar ratio of choline chloride to phenylpropionic acid is 1:1) into a 250 mL conical flask at a mass ratio of deep eutectic solvent to quinoline model oil of 1:5, and shake well to achieve preliminary mixing.

[0096] Place the conical flask in a constant temperature water bath at 40°C to ensure sufficient contact reaction for single-stage extraction. Transfer the mixed solution to a separatory funnel and allow it to stand for stratification. The upper layer is the denitrogenated oil product, and the lower layer is the low eutectic solvent loaded with basic nitrogen.

[0097] The denitrification process is completed by separating the upper and lower liquid layers using a separatory funnel or pipette. The raffinate is collected, washed, and dried to obtain a dealkalized nitrogen oil (basic nitrogen compound content: 168.75 μg / g), with a basic nitrogen removal rate of 87.5% and a dealkalized nitrogen oil yield of 99.2%. The extract is back-extracted with n-heptane at 50°C to remove the basic nitrogen compounds. The residual n-heptane is then evaporated to obtain the regenerated choline chloride / phenylpropionic acid deep eutectic solvent.

[0098] Table 2 Performance analysis of Example 7 and Comparative Example 3

[0099]

[0100] In Example 7, the decomposition product of aminosulfonic acid is ammonium sulfate, which can be used as fertilizer without secondary pollution; neutral sulfonate (-SO3 - ) Reduce the risk of metal corrosion.

[0101] It will be understood that the present invention is described by way of some embodiments, and it will be appreciated by those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are intended to be protected by the present invention.

Claims

1. A deep eutectic solvent for removing basic nitrogen compounds from oil products, characterized by: The deep eutectic solvent consists of a hydrogen bond acceptor and a hydrogen bond donor; The hydrogen bond acceptor is at least one of tetrabutylammonium bromide, L-carnitine, betaine, and tetramethylammonium chloride; The hydrogen bond donor is an aromatic ring or a C4~C 12 Sulfonic acid compounds with alkyl chains; The molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:1 to 1:

3.

2. The deep eutectic solvent for removing basic nitrogen compounds from oil products according to claim 1, characterized in that: The hydrogen bond donor is at least one of p-toluenesulfonic acid, 2-naphthalenesulfonic acid, dodecylbenzenesulfonic acid, and aminosulfonic acid.

3. The deep eutectic solvent for removing basic nitrogen compounds from oil products according to claim 1, characterized in that: The solvent viscosity of the deep eutectic solvent at 50° C. is ≤150 cP.

4. The method for preparing a deep eutectic solvent for removing basic nitrogen compounds from oil products according to any one of claims 1 to 3, characterized in that: The following steps are included: S101, mixing a hydrogen bond acceptor and a hydrogen bond donor in a molar ratio of 1:1 to 1:3; S102, stirring or ultrasonically treating the mixed solution in step S101 to form a transparent homogeneous liquid.

5. The method for preparing a deep eutectic solvent for removing basic nitrogen compounds from oil products according to claim 4, characterized in that: The method further includes step S103 of selectively adding 0-5% by mass of deionized water or ethanol to the transparent homogeneous liquid to adjust the solvent viscosity of the transparent homogeneous liquid.

6. The method for preparing a deep eutectic solvent for removing basic nitrogen compounds from oil products according to claim 4, wherein: In step S102 , the stirring or ultrasonication temperature is 60-80° C. and the time is 1-3 hours.

7. A method for using a deep eutectic solvent for removing basic nitrogen compounds from oil products, characterized in that: The deep eutectic solvent is a deep eutectic solvent for removing alkaline nitrides from oil products according to any one of claims 1 to 3 or a deep eutectic solvent prepared by the preparation method of a deep eutectic solvent for removing alkaline nitrides from oil products according to any one of claims 4 to 6, and the application method comprises the following steps: S201, mixing a deep eutectic solvent with an oil product; S202, stirring and extracting; S203, centrifugation and separation.

8. The method for using a deep eutectic solvent for removing basic nitrogen compounds from oil products according to claim 7, wherein: In step S201 , the mass ratio of the deep eutectic solvent to the oil product is 1:3 to 1:

6.

9. The method for using a deep eutectic solvent for removing basic nitrogen compounds from oil products according to claim 7, wherein: The extraction temperature in step S202 is 30-80° C., and the stirring time is 10-40 minutes.

10. The method for using a deep eutectic solvent for removing basic nitrogen compounds from oil products according to claim 7, wherein: In step S203, the centrifugal speed is 8000-10000 rpm, and the centrifugal time is ≤5 minutes.

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