Method for extracting and removing nitride in fuel oil by adopting double-acid eutectic solvent
By preparing a double-acidic low eutectic solvent and utilizing its synergistic acidic effect, the problem of low efficiency in removing nitrogen compounds from fuel in the existing technology is solved, and efficient and economical fuel refining effect is achieved.
Patent Information
- Application Number
- CN202510935421.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-08
- Publication Date
- 2025-10-10
AI Technical Summary
In existing denitrification technologies, a single acidic system is difficult to efficiently remove both alkaline and non-alkaline nitrogen compounds simultaneously. Insufficient anti-interference capability and an excessively high agent-to-oil ratio result in low fuel refining efficiency and increased costs.
A double-acidic deep eutectic solvent is prepared by combining lactic acid and metal chloride through the synergistic effect of Bronsted acid and Lewis acid, and is used for the extraction and removal of nitrogen compounds in fuel, thereby achieving the simultaneous deep removal of the two types of nitrogen compounds.
It significantly reduces operating energy consumption and solvent consumption, improves the efficiency and economy of fuel refining, and provides a green and simple denitrification method.
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Figure CN120758258A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of petrochemical industry, and particularly relates to a method for removing nitrogen compounds from fuel oil by extraction using a double-acidic deep eutectic solvent. Background Art
[0002] In recent years, with the continuous development of the petrochemical industry, fuel production has shown a rapid growth trend. However, the presence of organic nitrogen compounds (ONCs) in fuel oil poses a severe challenge to the environment and the oil processing process. Basic nitrogen compounds in crude oil, such as pyridine, quinoline and aniline, will poison the metal catalysts used in the oil refining process, reduce the activity of the catalyst, and thus reduce the efficiency of hydroprocessing operations such as hydrodesulfurization and hydrocracking, resulting in increased energy and hydrogen consumption, and thus increased costs and carbon emissions. Non-basic nitrogen-containing compounds, such as pyrrole, indole and carbazole, have an adverse effect on the thermal stability of fuel oil due to their easy self-oxidation and free radical addition reactions, further exacerbating the negative impact on the environment. In addition, organic nitrogen compounds are prone to generate nitrogen oxides (NO x ), which in turn causes environmental problems such as acid rain. Currently, hydrodenitrogenation (HDN) remains the primary method for removing nitrogen compounds in oil processing. This process converts ONCs into NH3 under high temperature and pressure. However, this process consumes significant amounts of hydrogen energy and remains inefficient. Therefore, a non-HDN method is urgently needed to treat ONCs in crude oil.
[0003] Among non-hydrogenation denitrification technologies, extractive denitrification (EDN) has attracted considerable attention due to its mild operating conditions, low energy consumption, and high efficiency. Its core principle is to achieve separation by exploiting the differential distribution of ONCs between the oil phase and the extract phase. Traditional organic solvents (such as methanol, furfural, acetonitrile, and sulfolane), while widely used, suffer from inherent drawbacks such as high volatility, high toxicity, and difficulty in recycling, limiting their industrial sustainability. Ionic liquids (ILs) are considered potential alternatives due to their low vapor pressure and non-flammability, but their high synthesis costs and susceptibility to water absorption and deterioration hinder their large-scale application. In recent years, deep eutectic solvents (DESs), emerging as green extractants, have emerged. These solvents are composed of low-cost components (such as quaternary ammonium salts and hydrogen bond donors) through molecular interactions such as hydrogen bonding. They combine the advantages of simple preparation and stable physicochemical properties, demonstrating their potential in the field of denitrification. For example, tetrabutylammonium bromide / formic acid DES can achieve removal rates of 99.60% and 98.42% for quinoline and indole, respectively. Choline chloride / phenylacetic acid DES also demonstrates the effectiveness of Brønsted acid in extracting nitrogen compounds.
[0004] However, existing DES systems still have significant limitations: First, most studies focus on single acidic (Brönsted or Lewis) systems, making it difficult to simultaneously and efficiently remove both basic and non-basic nitrogen compounds. Second, traditional DES lacks anti-interference capabilities in complex fuel systems. A large number of coexisting components in fuel (such as aromatics, olefins, and sulfides) may compete for extraction sites, significantly reducing denitrification efficiency. Third, to achieve deep denitrification, existing extraction systems often require high solvent-to-oil ratios (1:1 to 1:5), significantly increasing solvent consumption and subsequent separation costs. Summary of the Invention
[0005] Purpose of the invention: The technical problem to be solved by the present invention is to solve the defects of the existing denitrification technology, such as the difficulty of using a single acidic system to efficiently remove alkaline and non-alkaline nitrogen compounds at the same time, insufficient anti-interference ability and excessively high agent-oil ratio.
[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows:
[0007] A method for removing nitrogen compounds from fuel oil by extraction using a double-acidic deep eutectic solvent comprises the following steps:
[0008] (1) Lactic acid is fully stirred under heating, and then metal chloride is added and the reaction is continued with stirring. After the reaction is completed, the solution is vacuum dried to obtain a diacidic low eutectic solvent;
[0009] (2) The fuel to be treated is mixed and stirred with the double-acidic low eutectic solvent in step (1) to fully react and complete the extraction and nitrogen removal.
[0010] Furthermore, in step (1), the lactic acid is heated to 60-80°C and stirred for more than 0.5 h.
[0011] Furthermore, in step (1), the metal chloride is selected from at least one of aluminum chloride, zinc chloride, and copper chloride.
[0012] Furthermore, in step (1), the metal chloride is placed in a vacuum drying oven for drying in advance.
[0013] Furthermore, in step (1), the molar ratio of the lactic acid to the metal chloride is (10:1) to (20:1).
[0014] Furthermore, in step (1), the reaction speed is controlled at 350-800 r / min, and the reaction temperature is 60-100°C.
[0015] Furthermore, in step (1), the vacuum drying temperature is 60-90°C, and the drying time is 6-9 hours.
[0016] Furthermore, in step (2), the nitrogen compounds in the fuel to be treated include at least one of quinoline, pyrrole, indole, and aniline.
[0017] Furthermore, in step (2), the mass ratio of the fuel to be treated to the double-acidic low eutectic solvent is 1:1-30:1.
[0018] Furthermore, in step (2), the mass fraction of nitrogen compounds in the fuel to be treated is 0.005-0.05%wt.
[0019] Furthermore, in step (2), the reaction temperature is 25-70°C.
[0020] Beneficial effects:
[0021] (1) The present invention achieves the simultaneous deep removal of two types of nitrogen compounds (especially quinoline and pyrrole) in fuel oil by synergizing the dual effects of Brønsted acid and Lewis acid, significantly reducing operating energy consumption and solvent consumption, and providing an efficient and economical technical solution for green fuel oil refining.
[0022] (2) The di-acidic low eutectic solvent containing different metal chlorides synthesized in the present invention has different extraction and denitrification properties, and the differences are relatively large; the introduction of different metal chlorides greatly affects the extraction and denitrification performance.
[0023] (3) The double-acidic low eutectic solvent synthesized by the one-step synthesis method adopted in the present invention is simple to operate, has a short preparation cycle, a green process, high purity, low water content, and has good industrial prospects. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become more apparent.
[0025] Figure 1 This is the extraction and denitrification performance diagram of LA-AlCl3 for different nitrides.
[0026] Figure 2 Figure 2 shows the extraction and denitrogenation performance of di-acidic deep eutectic solvents for different metal chlorides (a) quinoline (b) pyrrole.
[0027] Figure 3 This is the extraction and denitrification performance diagram of LA-AlCl3 at different temperatures (a) quinoline (b) pyrrole.
[0028] Figure 4 Figure 2 is the extraction and denitrification performance of different ratios of nLA-AlCl3 and lactic acid (a) quinoline (b) pyrrole.
[0029] Figure 5 This is the infrared spectrum of pyridine, a doubly acidic deep eutectic solvent. DETAILED DESCRIPTION
[0030] The present invention can be better understood with reference to the following examples.
[0031] Example 1
[0032] 4.504 g of lactic acid was stirred under heating for 0.5 h, and then 0.6667 g of AlCl3 was added and the reaction continued under vacuum for 2 h to obtain a milky white opaque solution; the milky white solution was vacuum dried at 60°C for 6 h to obtain a lactic acid aluminum chloride di-acidic low eutectic solvent, recorded as LA-AlCl3.
[0033] Example 2
[0034] Take 4.504 g of lactic acid and stir it under heating for 0.5 h. Then add 0.6723 g of CuCl2 and continue to react under vacuum for 2 h to obtain a green transparent solution. The green solution is vacuum dried at 60°C for 6 h to obtain a lactic acid copper chloride diacidic low eutectic solvent, which is recorded as LA-CuCl2.
[0035] Example 3
[0036] Take 4.504 g of lactic acid and stir it under heating for 0.5 h, then add 0.6816 g of ZnCl2 and continue to react under vacuum for 2 h to obtain a milky white opaque solution; the milky white solution is vacuum dried at 60°C for 6 h to obtain a lactic acid aluminum chloride diacidic low eutectic solvent, recorded as LA-ZnCl2.
[0037] Example 4
[0038] The ratio of nitrogen-containing model oil to LA-AlCl3 oil agent is 30:1. Take 0.1g LA-AlCl3 and 3.0g 0.05%wt nitrogen-containing model oil, add them into the two-necked flask successively and quickly, and react at a speed of 600 r / min for 30 min; the two-necked flask is connected to a water bath to maintain a constant temperature of 30°C. Take 15 μL of the upper oil phase sample every five minutes. The residual amount of nitrogen compounds in the sample was detected by gas chromatography using the internal standard method and hexadecane as the internal standard. The nitrogen content and time curve was established with the residual amount of nitrogen compounds obtained by gas chromatography as the vertical coordinate and time as the horizontal coordinate, and the extraction equilibrium time was fitted and obtained. The average nitrogen content after the equilibrium time was taken as the final residual nitrogen content. The nitrogen content of the extraction phase was calculated, and the extraction efficiency was obtained. The results are shown in Figure 2. Figure 1 and as shown in Table 1.
[0039] Table 1
[0040]
[0041] Example 5
[0042] Take LA-AlCl3 prepared in Example 1, LA-CuCl2 prepared in Example 2, and LA-ZnCl2 prepared in Example 3, and perform extraction denitrification experiments respectively. The specific steps are as follows:
[0043] The ratio of quinoline (pyrrole) model oil to deep eutectic solvent was 30:1. 0.1 g of deep eutectic solvent and 3.0 g of 0.05% wt quinoline (pyrrole) model oil were added sequentially and rapidly to a two-necked flask. The reaction was incubated at 600 r / min for 60 min. The two-necked flask was connected to a water bath and maintained at a constant temperature of 25°C. 15 μL of the upper oil phase was sampled every ten minutes. The residual nitrogen compounds in the samples were determined by gas chromatography using hexadecane as the internal standard. A nitrogen content versus time curve was constructed, plotting the residual nitrogen compounds obtained by gas chromatography as the ordinate and time as the abscissa. The equilibrium time was calculated using the mean nitrogen content after the equilibrium time. The final residual nitrogen content was then calculated. The nitrogen content of the extract phase was then calculated, and the extraction efficiency was determined.
[0044] The results are as follows Figure 2 As shown in the figure, a is a quinoline model oil and b is a pyrrole model oil. It can be seen that all three deep eutectic solvents have excellent extraction performance for quinoline, completely removing it within 50 minutes. At 25°C, LA-CuCl2 achieves the best extraction efficiency for pyrrole, exceeding 90%, while the other two deep eutectic solvents also maintain extraction efficiencies above 80%. This demonstrates that the three deep eutectic solvents also have good extraction performance for nitrides at room temperature.
[0045] Example 6
[0046] Take the LA-AlCl3 prepared in Example 1 and conduct extraction denitrification experiments under different temperature conditions. The specific steps are as follows:
[0047] The ratio of quinoline (pyrrole) model oil to deep eutectic solvent was 30:1. 0.1 g of deep eutectic solvent and 3.0 g of 0.05% wt quinoline (pyrrole) model oil were added sequentially and rapidly to a two-necked flask. The reaction was continued at 600 r / min for 30 min. The two-necked flask was connected to a water bath and maintained at a constant temperature. 15 μL of the upper oil phase was sampled every five minutes. The residual nitrogen compounds in the samples were determined by gas chromatography using hexadecane as the internal standard. A nitrogen content versus time curve was constructed, with the residual nitrogen compounds obtained by gas chromatography as the ordinate and time as the abscissa. The equilibrium time was calculated using the mean nitrogen content after the equilibrium time. The final residual nitrogen content was then calculated. The nitrogen content of the extract phase was then calculated, and the extraction efficiency was determined.
[0048] The results are as follows Figure 3 As shown in the figure, a is the quinoline model oil and b is the pyrrole model oil. It can be seen that the quinoline extraction rate shows a downward trend with increasing temperature. This phenomenon may be attributed to the increase in the solubility of the solute in the solvent with increasing temperature. However, this increase in solubility is not always conducive to improving the extraction efficiency. Under certain conditions, the increase in the solubility of the target substance at higher temperatures may cause its solubility in the extractant to increase more than its solubility in the waste liquid, thereby reducing the extraction efficiency; while increasing temperature has a promoting effect on pyrrole extraction. As the temperature increases, the time to reach equilibrium becomes shorter, but when the temperature exceeds 30°C, the final extraction efficiency remains basically unchanged.
[0049] Example 7
[0050] According to the method of Example 1, the amount of AlCl3 was changed to prepare nLA-AlCl3 low eutectic solvents of different proportions. Specifically, 4.504 g of lactic acid was stirred under heating for 0.5 h, and then 0.4999 (0.3333) g of AlCl3 was added and the reaction was continued for 2 h under vacuum to obtain a milky white opaque solution; the milky white solution was vacuum dried at 60°C for 6 h to obtain a lactic acid aluminum chloride di-acidic low eutectic solvent, recorded as 15 (20) LA-AlCl3, and then an extraction denitrification experiment was carried out on it with lactic acid. The specific steps are as follows:
[0051] The ratio of quinoline (pyrrole) model oil to deep eutectic solvent or lactic acid oil was 30:1. 0.1 g of deep eutectic solvent or lactic acid and 3.0 g of 0.05% wt quinoline (pyrrole) model oil were added sequentially and rapidly to a two-necked flask. The reaction was continued at 600 rpm for 30 minutes. The two-necked flask was connected to a water bath and maintained at a constant temperature. Every five minutes, 15 μL of the upper oil phase was sampled. The residual nitrogen compounds in the samples were determined by gas chromatography using hexadecane as the internal standard. A nitrogen content versus time curve was constructed, with the residual nitrogen compounds obtained by gas chromatography as the ordinate and time as the abscissa. The equilibrium time was calculated using the average nitrogen content after the equilibrium time. The nitrogen content of the extract phase was calculated, and the extraction efficiency was determined.
[0052] The results are as follows Figure 4 As shown in the figure, a represents a quinoline model oil and b represents a pyrrole model oil. It can be seen that with increasing aluminum chloride content, the extraction efficiency for both basic and non-basic nitrogen compounds shows a significant upward trend. This demonstrates that the addition of Lewis acid enhances the extraction and denitrification performance of the system, and that this performance increases with increasing Lewis acid content.
[0053] Example 8
[0054] In order to test the diacidity of LA-AlCl3, pyridine infrared characterization was performed ( Figure 5 The results reveal the enhanced acidity of Brønsted acids in deep eutectic solvent systems. In the py + LA system, a characteristic peak of pyH⁺ is formed at approximately 1545 cm⁻¹, indicating a protonation reaction between pyridine and the Brønsted acid. In the py + LA-AlCl₃ system, this peak exhibits a significant blue shift, indicating an increase in the acidity of the Brønsted acid. This suggests that Lewis acids in deep eutectic solvent systems enhance the Brønsted acid, jointly improving the overall acidic environment.
[0055] The bis-acidic deep eutectic solvent described in the present invention has the advantages of simple synthesis process, mild conditions, readily available raw materials, environmental friendliness, and low cost. Its efficient denitrification performance provides a highly promising green and economical new technology approach for the refining and denitrification of fuel oil, which helps promote the sustainable development of the petrochemical industry and reduce environmental pollution.
[0056] The present invention provides a method and concept for extracting and removing nitrogen compounds from fuel oil using a double-acidic deep eutectic solvent. Numerous methods and approaches exist for implementing this technical solution. The foregoing merely represents a preferred embodiment of the present invention. It should be noted that those skilled in the art may make various improvements and modifications without departing from the principles of the present invention, and such improvements and modifications are considered within the scope of protection of the present invention. Any components not specified in this embodiment may be implemented using existing technologies.
Claims
1. A method for removing nitrogen compounds from fuel oil by extraction using a double-acidic deep eutectic solvent, characterized in that: The steps include: (1) Lactic acid is fully stirred under heating, and then metal chloride is added and the reaction is continued with stirring. After the reaction is completed, the solution is vacuum dried to obtain a diacidic low eutectic solvent; (2) The fuel to be treated is mixed and stirred with the double-acidic low eutectic solvent in step (1) to fully react and complete the extraction and nitrogen removal.
2. The method for removing nitrogen compounds from fuel oil by extraction using a double-acidic deep eutectic solvent according to claim 1, characterized in that: In step (1), the lactic acid is heated to 60-80°C and stirred for more than 0.5 h.
3. The method for removing nitrogen compounds from fuel oil by extraction using a double-acidic deep eutectic solvent according to claim 1, characterized in that: In step (1), the metal chloride is selected from at least one of aluminum chloride, zinc chloride and copper chloride.
4. The method for removing nitrogen compounds from fuel oil by extraction using a double-acidic deep eutectic solvent according to claim 1, characterized in that: In step (1), the molar ratio of the lactic acid to the metal chloride is (10:1) to (20:1).
5. The method for removing nitrogen compounds from fuel oil by extraction using a double-acidic deep eutectic solvent according to claim 1, characterized in that: In step (1), the reaction speed is controlled at 350-800 r / min and the reaction temperature is 60-100 °C.
6. The method for removing nitrogen compounds from fuel oil by extraction using a double-acidic deep eutectic solvent according to claim 1, characterized in that: In step (1), the vacuum drying temperature is 60-90°C and the drying time is 6-9 hours.
7. The method for removing nitrogen compounds from fuel oil by extraction using a double-acidic deep eutectic solvent according to claim 1, characterized in that: In step (2), the nitrogen compounds in the fuel to be treated include at least one of quinoline, pyrrole, indole, and aniline.
8. The method for removing nitrogen compounds from fuel oil by extraction using a double-acidic deep eutectic solvent according to claim 1, characterized in that: In step (2), the mass ratio of the fuel to be treated to the double-acidic low eutectic solvent is 1:1-30:
1.
9. The method for removing nitrogen compounds from fuel oil by extraction using a double-acidic deep eutectic solvent according to claim 1, characterized in that: In step (2), the mass fraction of nitrogen compounds in the fuel to be treated is 0.005-0.05%wt.
10. The method for removing nitrogen compounds from fuel oil by extraction using a double-acidic deep eutectic solvent according to claim 1, characterized in that: In step (2), the reaction temperature is 25-70 °C.