Ternary eutectic solvent extraction agent for deep denitrification of oil product and preparation method thereof

Abstract

The invention relates to the field of energy conservation and environmental protection, in particular to a ternary eutectic solvent extraction agent for deep denitrification of an oil product and a preparation method of the ternary eutectic solvent extraction agent. The extraction agent is prepared by taking tetrabutylammonium chloride as a hydrogen bond acceptor and ethylene glycol and oxalic acid as hydrogen bond donors according to a molar ratio of 1: 1: 1 through one-step heating and stirring at 80 DEG C for 3 hours, and is a uniform and transparent liquid at room temperature. According to the ternary system, the problem that tetrabutylammonium chloride-oxalic acid is difficult to form a phase is successfully solved through introduction of ethylene glycol, more active sites are provided, and alkaline and non-alkaline nitrides such as indole, quinoline, pyrrole and pyridine can be efficiently extracted at the same time. The nitrogen removal efficiency of various nitrides is always kept at an excellent level and can generally reach more than 90% by extracting the nitrogen-containing normal octane simulation oil according to the mass ratio of 1: 10-1: 30 at 20-60 DEG C for 5-90 minutes; the method has the advantages of cheap raw materials, simple process, mild conditions, good cycle performance and environmental friendliness, and is suitable for deep denitrification of gasoline, diesel oil, lubricating oil and other oil products.

Description

Technical Field

[0001] This invention relates to the field of energy conservation and environmental protection, and in particular to a ternary eutectic solvent extractant for deep denitrification of oil products and its preparation method. Background Technology

[0002] Nitrogen oxides (NO) x Nitrogen oxides (NOx) are major air pollutants, causing not only environmental hazards such as acid rain and smog, but also pollution and damage to water bodies, soil, human health, and ecosystems. The primary source of NOx is the combustion of nitrogen-containing fuel oils. The presence of NOxes not only pollutes the environment but also reduces the performance and storage quality of fuel oils, and inhibits desulfurization during subsequent processing. Therefore, removing NOxes from fuel oils is of great significance for ecological environmental protection and improving fuel quality.

[0003] Currently, nitrogen compounds in petroleum products are mainly classified into two categories: basic nitrogen compounds (quinoline, pyridine, and aniline, etc.) and non-basic nitrogen compounds (indole, pyrrole, and carbazole, etc.). The most widely used denitrification method in industry is hydrodenitrification, but this technology suffers from drawbacks such as high cost, demanding conditions, and low denitrification rates. Therefore, non-hydrodenitrification methods have attracted increasing attention. Among these, extractive denitrification shows promising research prospects due to its mild reaction conditions and simple operation.

[0004] Traditional organic solvents and emerging ionic liquids generally suffer from low extraction efficiency, inability to simultaneously and effectively remove basic and non-basic nitrogen compounds, high cost, and toxicity risks. Eutectic solvents (DESs), as a novel type of green material, are synthesized by directly mixing hydrogen bond acceptors (HBAs) such as metal halides and quaternary ammonium salts with hydrogen bond donors (HBDs) such as alcohols, amides, and carboxylic acids. They not only possess advantages such as low volatility, customizable physicochemical properties, and wide applicability, but also feature green and inexpensive raw materials, simple preparation processes, and excellent environmental compatibility.

[0005] Tetrabutylammonium chloride is the most common quaternary ammonium salt compound. Ethylene glycol and oxalic acid are both basic chemical raw materials widely used in industry, with abundant sources and low prices, reducing synthesis costs. Ternary eutectic solvents have more reactive sites than ionic liquids and ordinary eutectic solvents, providing a new pathway to improve the efficiency of oil denitrification (indole, quinoline, pyrrole, and pyridine). Summary of the Invention

[0006] This invention can simultaneously and effectively extract indole, quinoline, pyrrole and pyridine from fuel oil. This method is low in cost, simple to operate, mild under mild conditions, high extraction efficiency and good environmental compatibility.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] 1. Ternary eutectic solvent extractant The extractant is formed by the self-assembly of hydrogen bond acceptor tetrabutylammonium chloride (TBAC) and hydrogen bond donors ethylene glycol (EG) and oxalic acid (OA) in a molar ratio of 1:1:1 via hydrogen bonding. It is a homogeneous, transparent, and clear liquid at room temperature. Its structural diagram is shown below:

[0009] 2. Preparation method (1) Pretreatment: Tetrabutylammonium chloride, ethylene glycol and oxalic acid were placed in a vacuum oven and dried for 48 h at a vacuum of 0.09 MPa and 50-65 °C to remove moisture and low-boiling-point impurities.

[0010] (2) Synthesis: The dried TBAC, EG and OA were added to a three-necked flask with magnetic stirring in a molar ratio of 1:1:1. The mixture was stirred at 70-90 °C under normal or reduced pressure for 2-4 h until the system became a homogeneous transparent liquid. After vacuum drying, the ternary eutectic solvent was obtained.

[0011] 3. Methods for deep denitrogenation of oil products The above-mentioned ternary eutectic solvent extractant was mixed with an octane-based simulated oil containing at least one of indole, quinoline, pyrrole, or pyridine at a mass ratio of 1:10 to 1:30, and extracted with magnetic stirring in a constant temperature water bath at 20–60 °C for 5–90 min. After the reaction, the mixture was allowed to stand and separate into layers; the upper layer was the denitrified oil, and the lower layer was the extract phase loaded with nitrogen compounds. Isopropyl ether back-extraction was used to regenerate the extract phase and recover the nitrogen compounds. The concentration of indole, quinoline, pyrrole, or pyridine in the octane-based simulated oil was 500–2500 mg / L.

[0012] Compared with the prior art, the present invention has the following significant advantages:

[0013] 1. The ternary eutectic solvent prepared by this invention is inexpensive, simple to prepare, environmentally friendly, non-volatile, and liquid at room temperature, making it a promising green solvent.

[0014] 2. The ternary eutectic solvent prepared by the present invention effectively avoids the problem that tetrabutylammonium chloride and oxalic acid cannot form a eutectic solvent by adding ethylene glycol, and finally successfully obtains the ternary eutectic solvent.

[0015] 3. The ternary eutectic solvent prepared by this invention can provide more reaction sites and has a strong removal ability for indole, quinoline, pyrrole and pyridine.

[0016] 4. The ternary eutectic solvent prepared by this invention has the advantages of mild reaction conditions, short reaction time, and high removal efficiency with very small dosage when used to remove nitrogen oxides from oil products. Attached Figure Description

[0017] Figure 1 The image shows the proton NMR spectrum of the tetrabutylammonium chloride-ethylene glycol-oxalic acid ternary eutectic solvent prepared in Example 1.

[0018] Figure 2 The image shows the infrared spectrum of the tetrabutylammonium chloride-ethylene glycol-oxalic acid ternary eutectic solvent prepared in Example 1. Detailed Implementation

[0019] The present invention will be further illustrated by specific examples below. The present invention is not limited to the embodiments described, and minor variations may be made without departing from the scope thereof.

[0020] The present invention will be further illustrated by specific examples below. The present invention is not limited to the embodiments described, and minor variations may be made without departing from the scope thereof. Example 1

[0021] A method for preparing a ternary eutectic solvent extractant is as follows: 1) Tetrabutylammonium chloride, ethylene glycol and oxalic acid were vacuum dried at a vacuum degree of 0.09 MPa and a temperature of 60 °C for 48 h.

[0022] 2) Weigh tetrabutylammonium chloride, ethylene glycol, and oxalic acid separately in a molar ratio of 1:1:1, and then place them in a flask equipped with a stirrer. React at 80 °C for 3 h. After the reaction, dry under vacuum at 0.09 MPa and 60 °C for 48 h to obtain the final ternary eutectic solvent extractant.

[0023] Characterization of ternary eutectic solvents: (1) Proton NMR spectrum: Proton NMR spectrum of ternary eutectic solvent ( 1 Characterization by 1H NMR (solvent: DMSO-) d 6) As attached Figure 1 As shown. Spectral analysis indicates that, 1 The chemical shifts and number of resonance peaks of the H NMR were consistent with those of the target eutectic solvent, and no impurity peaks were observed.

[0024] (2) Infrared spectrum: The infrared characterization of the ternary eutectic solvent is shown in the attached figure. Figure 2 As shown in the figure, infrared spectrum analysis revealed that the infrared spectrum of the eutectic solvent contained characteristic peaks of both hydrogen bond acceptors (tetrabutylammonium chloride) and hydrogen bond donors (ethylene glycol and oxalic acid), and no new characteristic peaks were generated. This indicates that no chemical reaction occurred between tetrabutylammonium chloride, ethylene glycol, and oxalic acid to produce new substances; they were simply bonded together through hydrogen bond interactions. Example 2

[0025] A method for preparing a ternary eutectic solvent extractant is as follows: 1) Tetrabutylammonium chloride, ethylene glycol and oxalic acid were vacuum dried at a vacuum degree of 0.09 MPa and a temperature of 50 °C for 48 h.

[0026] 2) Weigh tetrabutylammonium chloride, ethylene glycol, and oxalic acid separately in a molar ratio of 1:1:1, and then place them in a flask equipped with a stirrer. React at 90 °C for 3 h. After the reaction, dry under vacuum at 0.09 MPa and 60 °C for 48 h to obtain the final ternary eutectic solvent extractant. Example 3

[0027] A method for preparing a ternary eutectic solvent extractant is as follows: 1) Tetrabutylammonium chloride, ethylene glycol and oxalic acid were vacuum dried at a vacuum degree of 0.09 MPa and a temperature of 65 °C for 48 h.

[0028] 2) Weigh tetrabutylammonium chloride, ethylene glycol, and oxalic acid separately in a molar ratio of 1:1:1, and then place them in a flask equipped with a stirrer. React at 70 °C for 4 h. After the reaction, dry under vacuum at 0.09 MPa and 60 °C for 48 h to obtain the final ternary eutectic solvent extractant.

[0029] In the following examples, the simulated fuel oil used was prepared by dissolving indole, quinoline, pyrrole, and pyridine in a prepared n-octane simulated oil to achieve a nitrogen concentration of 500-2500 ppm. After denitrogenation, the concentrations of indole (289 nm), quinoline (313 nm), pyrrole (220 nm), and pyridine (254 nm) in the n-octane phase were determined by UV-Vis spectrophotometry. At least three parallel samples were taken from the n-octane phase for quantitative determination of each target compound, and the relative error at equilibrium was controlled within 2% to ensure data accuracy. The extraction efficiency (E%) of the four nitrides was calculated according to formula (1-1): (1-1) in, C 0 represents the initial concentration of indole, quinoline, pyrrole, or pyridine in the simulated oil. C 1 indicates its remaining concentration in the n-octane phase.

[0030] All application examples below are based on the ternary eutectic solvent extractant prepared in Example 1.

[0031] In Application Example 1, 1 g of a ternary eutectic solvent was weighed and placed in a 20 mL sample bottle. 10 g of simulated oil with a nitrogen concentration of 500 ppm was added. Extraction was performed at 25 °C with magnetic stirring at 300 rpm for 40 min. After the reaction, the mixture was allowed to stand for 30 minutes to allow for layering. The extraction efficiencies for indole, quinoline, pyrrole, and pyridine were measured to be 97.08%, 99.76%, 92.69%, and 99.60%, respectively.

[0032] 1 g of ternary eutectic solvent was weighed and placed in a 20 mL sample vial. 10 g of simulated oil with a nitrogen concentration of 500 ppm was added. Extraction was carried out at 30 °C with magnetic stirring at 300 rpm for 40 min. After the reaction, the mixture was allowed to stand for 30 minutes to allow the solution to separate into layers. The extraction efficiencies of indole, quinoline, pyrrole, and pyridine were measured to be 95.92%, 99.69%, 91.70%, and 99.38%, respectively.

[0033] 1 g of ternary eutectic solvent was weighed and placed in a 20 mL sample vial. 20 g of simulated oil with a nitrogen concentration of 500 ppm was added. Extraction was carried out at 25 °C with magnetic stirring at 300 rpm for 40 min. After the reaction, the mixture was allowed to stand for 30 minutes to allow the solution to separate into layers. The extraction efficiencies of indole, quinoline, pyrrole, and pyridine were measured to be 86.99%, 95.91%, 84.69%, and 95.39%, respectively.

[0034] 1 g of ternary eutectic solvent was weighed and placed in a 20 mL sample vial. 10 g of simulated oil with a nitrogen concentration of 500 ppm was added. Extraction was carried out at 25 °C with magnetic stirring at 300 rpm for 10 min. After the reaction, the mixture was allowed to stand for 30 minutes to allow the solution to separate into layers. The extraction efficiencies of indole, quinoline, pyrrole, and pyridine were measured to be 77.37%, 89.91%, 81.70%, and 94.66%, respectively.

[0035] 1 g of ternary eutectic solvent was weighed and placed in a 20 mL sample vial. 10 g of simulated oil with a nitrogen concentration of 1000 ppm was added. Extraction was carried out at 25 °C with magnetic stirring at 300 rpm for 40 min. After the reaction was completed, the mixture was allowed to stand for 30 minutes to allow the solution to separate into layers. The extraction efficiencies of indole, quinoline, pyrrole, and pyridine were measured to be 92.37%, 98.51%, 88.48%, and 99.40%, respectively.

[0036] For the eutectic solvent (DESs) after nitride extraction, the following regeneration process was used: 20 mL of deionized water was added, and isopropyl ether was added as the back-extraction agent, with an equal volume of isopropyl ether added to the aqueous phase. The mixture was back-extracted at 25 °C for 30 min. After the system was allowed to stand until the two phases completely separated, the lower aqueous phase containing DESs was collected (because the density of isopropyl ether is less than that of the aqueous phase, the upper layer is the isopropyl ether phase containing nitrides). The back-extraction operation was repeated twice to fully remove the nitrides from the DESs, yielding an aqueous solution of regenerated DESs. This aqueous solution was then transferred to a rotary evaporator and subjected to vacuum distillation at 0.09 MPa and 60 °C to remove water from the system, finally obtaining the regenerated DESs. After four regenerations of DESs, the extraction efficiencies for indole, quinoline, pyrrole, and pyridine were 93.60%, 96.87%, 87.32%, and 98.32%, respectively.

[0037] The above description is only of the preferred embodiment of the present invention and should not be construed as limiting the scope of the claims. The present invention is not limited to the above embodiments, and all variations made within the scope of the independent claims of the present invention are within the scope of protection of the present invention.

Claims

1. A ternary eutectic solvent extractant for deep denitrogenation of oil products, characterized in that, The ternary eutectic solvent is made of tetrabutylammonium chloride, ethylene glycol, and oxalic acid, and the structural formula of the ternary eutectic solvent is as follows:

2. A method for preparing a ternary eutectic solvent extractant for deep denitrogenation of oil products, characterized in that, Includes the following steps: Tetrabutylammonium bromide, ethylene glycol, and oxalic acid were placed in a vacuum oven for drying. Synthesis of ternary eutectic solvent: Dried tetrabutylammonium chloride, ethylene glycol and oxalic acid are mixed in a certain molar ratio and stirred under heating conditions until a homogeneous, transparent and clear liquid is formed. After vacuum drying, the ternary eutectic solvent is obtained.

3. The method for preparing a ternary eutectic solvent extractant for deep denitrogenation of oil products according to claim 2, characterized in that, The conditions described in step 1) are a vacuum of 0.09 MPa and a temperature of 50-65 ℃ for 48 hours.

4. The method for preparing a ternary eutectic solvent extractant for deep denitrogenation of oil products according to claim 2, characterized in that, The molar ratio of tetrabutylammonium chloride, ethylene glycol and oxalic acid in step 2) is 1:1:

1.

5. The method for preparing a ternary eutectic solvent extractant for deep denitrogenation of oil products according to claim 2, characterized in that, The heating temperature in step 2) is 70-90 ℃, and the reaction time is 2-4 h.

6. A ternary eutectic solvent extractant for deep denitrogenation of oil products as described in claim 1, characterized in that, The method for extracting nitrogen compounds includes: mixing the ternary eutectic solvent with n-octane simulated oil containing at least one nitrogen compound selected from indole, quinoline, pyrrole or pyridine; carrying out the extraction reaction under the conditions of set temperature, solvent-to-oil mass ratio, initial nitrogen compound concentration and extraction time; after the reaction is completed, allowing the mixture to stand and separate into layers; and taking the upper liquid is the denitrified oil.

7. A ternary eutectic solvent extractant for deep denitrogenation of oil products according to claim 6, characterized in that, The reaction process of mixing oil and extractant with nitrogen-containing n-octane was simulated, and the reaction temperature was 20~60 ℃.

8. A ternary eutectic solvent extractant for deep denitrogenation of oil products according to claim 6, characterized in that, The mass ratio of the ternary eutectic solvent to the n-octane simulated oil is 1:10 to 1:

30.

9. A ternary eutectic solvent extractant for deep denitrogenation of oil products according to claim 6, characterized in that, The extraction reaction time is 5-90 min.

10. A ternary eutectic solvent extractant for deep denitrogenation of oil products according to claim 6, characterized in that, The concentration of indole, quinoline, pyrrole, or pyridine in the n-octane-based simulated oil is 500–2500 mg / L.

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