Method for coupling desulfurization by ion liquid extraction electrocatalytic oxidation

Abstract

This invention discloses a novel method for coupled electrocatalytic oxidation desulfurization using ionic liquid extraction. The ionic liquid acts as both a catalyst to accelerate the oxidative desulfurization reaction and an extractant to promote the rapid extraction of sulfides. This innovative method significantly improves the desulfurization speed and efficiency, increasing the reaction rate by approximately 20 times compared to traditional oxidative desulfurization technologies. Furthermore, this invention uses simulated seawater (hereinafter referred to as acidic brine) as the electrolyte, enabling in-situ generation of the oxidant and effectively utilizing the Cl- at the anode. ‑ The oxidation reaction produces ClO, which has catalytic oxidation properties. ‑ This innovation not only improves the efficiency of hydrogen production from seawater electrolysis but also avoids the inefficiency and safety hazards associated with traditional oxidants. Given the abundance and low cost of seawater resources, this technology is suitable for implementation around refineries because it eliminates the need for additional oxidants, thereby reducing the cost of ultra-deep desulfurization and enhancing the safety of the desulfurization process.

Description

Technical Field

[0001] This invention belongs to the field of petrochemical electrochemical desulfurization technology, specifically relating to a novel method for desulfurization coupled with ionic liquid extraction and electrocatalytic oxidation. Background Technology

[0002] With increasing global demands for environmental governance and the deepening of energy transition, the problem of sulfides in fossil fuels such as diesel has become particularly prominent. The acid rain and PM2.5 pollution generated from the combustion of these sulfides pose a serious threat to ecological security and human health. To address this challenge, many countries and regions, including China, the United States, and the European Union, have introduced strict regulations limiting the concentration of sulfides in fuel oil to no more than 10 μg / g. However, with the deepening of oil extraction, the quality of crude oil is gradually declining; for example, the sulfur content in Venezuelan crude oil exceeds 5.5 wt.%, which presents a significant challenge to desulfurization processes. Traditional hydrodesulfurization (HDS) technology is inefficient in treating aromatic sulfides, and with the decline in crude oil quality, the required temperature and pressure increase significantly, leading to a substantial increase in energy consumption and carbon emissions. Therefore, researchers have developed various non-hydrodesulfurization technologies, such as adsorption desulfurization (ADS), extraction desulfurization (EDS), oxidative desulfurization (ODS), and biological desulfurization (BDS), among which oxidative desulfurization (ODS) has attracted considerable attention due to its high efficiency and mild reaction conditions.

[0003] In the ODS process, aromatic sulfur compounds are converted into more polar sulfones through peroxidation. However, this process requires the addition of costly and inefficient oxidants, such as hydrogen peroxide and organic peroxides. Therefore, the development of novel ODS desulfurization processes is urgent. Meanwhile, to achieve large-scale hydrogen production through water electrolysis, many studies have reported methods for producing hydrogen through seawater electrolysis. In the seawater electrolysis process, Cl at the anode... - ClO produced by oxidation - It exhibits excellent catalytic oxidation performance and can be used for the catalytic desulfurization of aromatic sulfides to construct an electrocatalytic oxidative desulfurization system (E-ODS). This method not only efficiently utilizes the low-value Cl- oxidation reaction but also eliminates voltage limitations in the seawater electrolysis hydrogen production process, significantly improving hydrogen production efficiency. By controlling the voltage of the applied electric field, the electrochemical catalytic oxidation performance can be controlled to obtain even better ODS performance. Furthermore, since refineries are mostly built near the sea, abundant seawater resources are beneficial for constructing E-ODS systems, reducing desulfurization costs, improving safety, and simultaneously achieving efficient hydrogen production at the cathode. The produced hydrogen can be directly used in the refining process, reducing costs for refining companies.

[0004] Although the E-ODS system is still in its early stages of research, it has shown great potential in mass transfer and electron transfer. In the E-ODS system, sulfide molecules need to diffuse from the fuel to the electrolyte and then to the electrode, but the polarity difference between the fuel and the electrolyte leads to low mass transfer and diffusion efficiency. Furthermore, the electric double layer in the E-ODS process hinders electron transfer, reducing efficiency. Therefore, enhancing the mass transfer and charge transfer efficiency of the E-ODS system and overcoming the resistance to mass transfer and diffusion and the electric double layer are crucial for achieving efficient oxidative desulfurization. Summary of the Invention

[0005] Purpose of the invention: The technical problem to be solved by this invention is to address the shortcomings of existing oxidative desulfurization technologies, especially the ClO produced during the electrolysis of seawater to produce hydrogen. - To address the issue of utilizing substances such as ionic liquids, this paper proposes a desulfurization method based on ionic liquid extraction-electrocatalytic oxidation coupled with electrochemical desulfurization, which shortens the desulfurization time and improves the oxidation efficiency.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A novel method for desulfurization coupled with ionic liquid extraction and electrocatalytic oxidation includes the following steps:

[0008] (1) Prepare an aqueous solution of sulfuric acid;

[0009] (2) Dissolve the soluble metal chloride salt in the sulfuric acid aqueous solution obtained in step (1) to prepare an acidic brine electrolyte;

[0010] (3) Add the ionic liquid to the acidic brine electrolyte in step (2) and mix thoroughly to form a homogeneous acidic brine electrolyte containing the ionic liquid;

[0011] (4) Add the fuel oil to be desulfurized to the acidic brine electrolyte containing ionic liquid in step (3), and electrolyze it under a constant current of DC power supply until the sulfides in the fuel oil are completely removed.

[0012] (5) Separate fuel oil and electrolyte to achieve complete removal of sulfides in the oil phase and convert them into desulfurization product DBTO2.

[0013] Specifically, in step (1), the mass fraction of the sulfuric acid aqueous solution is 5-15%.

[0014] Specifically, in step (2), the soluble metal chloride salt is selected from any one of the common seawater chloride salts such as KCl, NaCl, MgCl2, and CaCl2; the concentration of the soluble metal chloride salt in the obtained acidic brine electrolyte is 0.15~0.2 mol / L.

[0015] Specifically, in step (3), the ionic liquid is any one of the ionic liquids that can be used to extract sulfides, such as [Bmim]BF4, [Bmim]PF6, [Omim]BF4, and [Omim]PF6.

[0016] Specifically, in step (3), the ionic liquid and the acidic salt electrolyte are mixed at a volume ratio of 1 to 5:5.

[0017] Specifically, in step (3), the mixing temperature is controlled at 40~80℃, the time is 5~10 minutes, and the stirring speed is 400~800 rpm.

[0018] Specifically, in step (4), the fuel oil to be desulfurized includes any one of DBT, 4-MDBT, and 4,6-DMDBT.

[0019] Specifically, in step (4), the ionic liquid acidic brine electrolyte is mixed with the fuel oil to be desulfurized at a volume ratio of 1:1 to 3.

[0020] Specifically, in step (4), the current is 100~200 mA and the electrolysis reaction time is 15~20 min.

[0021] Specifically, in step (5), fuel oil and electrolyte are separated by a liquid separation method.

[0022] In recent years, many studies have reported methods for producing hydrogen through seawater electrolysis in order to achieve large-scale water electrolysis. However, in the process of seawater electrolysis, the anode's reaction with Cl... - Oxidation produces Cl2 or ClO - Substances such as ClO are generally considered unfavorable for the large-scale application of hydrogen production through water electrolysis. However, this invention has discovered that ClO... - It exhibits excellent catalytic oxidation performance in oxidative desulfurization (ODS) processes. Therefore, this invention proposes an electrocatalytic oxidative desulfurization system (E-ODS) that fully utilizes the low-value Cl- at the anode during seawater electrolysis for hydrogen production. - The oxidation reaction generates an oxidant in situ, which is then used to catalyze the oxidative desulfurization of aromatic sulfides, thereby achieving a low-value Cl... -The efficient utilization of the oxidation reaction allows the electrolysis of seawater for hydrogen production to no longer be limited by voltage, enabling it to proceed under high voltage and high current, significantly improving the hydrogen production efficiency of seawater electrolysis. By controlling the voltage of the applied electric field, the electrochemical catalytic oxidation performance can be controlled, resulting in superior ODS performance. Furthermore, oil refineries are often built near the coast, typically surrounded by abundant seawater resources, which is conducive to constructing an E-ODS system. This invention not only eliminates the need for external oxidants, reducing the cost of ultra-deep fuel desulfurization and improving desulfurization safety, but also, due to the full utilization of the anode side reaction, enables the cathode to efficiently produce hydrogen under high voltage and high current. The produced hydrogen can be directly used for hydrorefining in the oil refining process, avoiding additional hydrogen storage and transportation, and is expected to significantly reduce the costs for oil refining companies.

[0023] By introducing the ionic liquid [Bmim]BF4 as an extractant and reaction medium into the E-ODS system, it is expected to enhance the mass transfer and diffusion of sulfide molecules from the fuel phase to the electrolyte phase, and eliminate the electric double layer at the electrode-electrolyte interface through ionic balance, thereby enhancing electron transfer and improving desulfurization performance. Ionic liquids have attracted widespread attention due to their excellent solubility, high chemical and thermal stability, excellent conductivity, and virtually no vapor pressure. In the ionic liquid-based extraction-coupled catalytic oxidation desulfurization system, sulfides in the fuel are extracted and enriched by the ionic liquid, and further catalytic oxidation reactions occur in the ionic liquid phase, breaking the extraction equilibrium and achieving deep desulfurization. Constructing an innovative ionic liquid acidic brine electrolyte has proven to be a feasible and ingenious method in this invention, which can avoid the process of sulfide polymerization and dissolution, and improve the efficiency of deep desulfurization. Beneficial effects

[0024] (1) The acidic brine electrolyte used in this invention generates oxidants in situ, effectively avoiding the safety risks, low efficiency, and oil peroxidation problems caused by continuous addition of oxidants later. On the other hand, due to the abundance and low cost of seawater resources and the mild reaction conditions, coupled with the introduction of ionic liquids, a concentration gradient is formed between the oil and the electrolyte, which significantly accelerates the desulfurization rate. When the current is turned on, the desulfurization reaction can start instantaneously, and the reaction rate is increased by about 20 times compared with traditional oxidative desulfurization.

[0025] (2) This invention utilizes the extraction performance of ionic liquids on sulfides in oil products to extract DBTO2, a high-value-added product generated by in-situ oxidation, into the electrolyte, thereby obtaining oil products with completely removed sulfides and an electrolyte containing DBTO2. The two can be separated by liquid-liquid separation.

[0026] (3) The ionic liquid extraction electrocatalytic oxidation coupled desulfurization method designed in this invention has wide applicability and can effectively remove different types of sulfides, such as DBT, 4-MDBT, 4,6-DMDBT, etc.

[0027] (4) The synthesis method used in this invention is simple to operate, green and environmentally friendly, and has good application prospects and market potential. Attached Figure Description

[0028] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0029] Figure 1 This is a schematic diagram of the novel ionic liquid extraction-electrocatalytic oxidation coupled desulfurization process of this invention.

[0030] Figure 2 This experiment demonstrates the effect of electrolyte composition on the DBT activity in fuel oil using this experimental method.

[0031] Figure 3 This demonstrates the effect of reaction conditions on the DBT activity in fuel in this experimental method. Detailed Implementation

[0032] The present invention can be better understood from the following embodiments. Example 1

[0033] (1) Dilute concentrated sulfuric acid (98% by mass) to a sulfuric acid solution (10% by mass), and measure 10 ml of the sulfuric acid solution into a jacketed beaker.

[0034] (2) Weigh out 0.1169 g of sodium chloride and dissolve it in 10 ml of sulfuric acid solution to prepare 0.2 mol / L simulated seawater.

[0035] (3) Take 6 ml of ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate). The ionic liquid used in the future will be 1-butyl-3-methylimidazolium tetrafluoroborate. At this time, the electrolyte is divided into two phases: the ionic liquid phase and the acidic salt water phase. A homogeneous electrolyte system has not yet been formed.

[0036] (4) The two phases in step 3 are stirred at 600 rpm for 10 minutes at 60°C to obtain a clear solution, which forms a homogeneous electrolyte phase. This system can continuously extract sulfides from the oil phase into the electrolyte phase. The extracted sulfides are oxidized at the anode into the high-value-added product DBTO2, maintaining the concentration gradient between the oil phase and the electrolyte phase, thereby significantly improving the desulfurization efficiency of electro-oxidation extraction coupling.

[0037] (5) Measure 10 ml of model oil (solute: DBT concentration of 400 ppm, internal standard: hexadecane concentration of 4000 ppm, solvent: dodecane) and make the ratio of its volume to the acidic saline system 1:1.

[0038] (6) Use a constant temperature water bath to control the reaction temperature at 30℃, use a magnetic stirrer to control the stirring speed at 500 rpm, and apply a constant current of 150 mA. Both the positive and negative electrodes are ordinary graphite electrodes, with the positive electrode being the site where the oxidation reaction occurs.

[0039] Figure 1 This is a schematic diagram of the novel ionic liquid extraction-electrocatalytic oxidation coupled desulfurization process of this invention.

[0040] Figure 2 This demonstrates the effect of electrolyte variables on the DBT activity in fuel in this experimental method.

[0041] in: Figure 2 Figure A shows the effect of adjusting the H2SO4 concentration on the DBT activity in fuel. As can be seen from the figure, excessive sulfuric acid concentration can easily corrode the graphite electrode, so an appropriate concentration of sulfuric acid should be selected.

[0042] Figure 2 Figure B illustrates the effect of adjusting the NaCl concentration in the electrolyte on the DBT activity in fuel. As can be seen from the figure, adding NaCl provides more oxidation units and improves the conductivity of the solution, leading to the generation of ClO at the anode. - The higher the concentration, the more oxidation units are provided, and the higher the desulfurization rate.

[0043] Figure 2 Figure C shows the effect of different types of ionic liquids on the DBT activity in fuel. As can be seen from the figure, only [Bmim]BF4 can achieve miscibility with water in any proportion to form a homogeneous ionic liquid acidic salt electrolyte, which makes NaCl dissolve better in the electrolyte, the electrolyte is evenly distributed, and the ion mass transfer is enhanced, thus exhibiting good electrochemical desulfurization performance.

[0044] Figure 2 Figure D shows the effect of the amount of ionic liquid in the electrolyte on the DBT activity in the fuel. As can be seen from the figure, the extraction effect brought by the ionic liquid plays a key role in the ionic liquid extraction-electrocatalytic oxidation coupled electrochemical desulfurization scheme of this scheme.

[0045] Figure 3 This experiment demonstrates the effect of oil type variables on the DBT activity in fuel oil using this experimental method.

[0046] in: Figure 3 Figure A shows the effect of electrolyte on DBT activity in fuel at different temperatures. As can be seen from the figure, this scheme can be carried out at room temperature, and different temperatures have little effect on ionic liquid extraction-electrocatalytic oxidation coupled electrochemical desulfurization. Figure 3 B shows the kinetic fitting plots at different temperatures. It can be seen from the plots that the scheme is under pseudo-first-order kinetics from 0 to 20 min.

[0047] Figure 3 Figure C shows the effect of electrolyte on DBT activity in fuel under different constant currents. As can be seen from the figure, when the constant current exceeds a certain value, the desulfurization rate decreases despite the increase in current. This indicates that a higher application current may break down the electrode and does not necessarily lead to higher desulfurization efficiency.

[0048] Figure 3 Figure D shows the effect of electrolyte on DBT activity in fuel at different stirring speeds. As can be seen from the figure, with the increase of stirring speed, the mass transfer rate between the oil phase and the water phase increases, which accelerates the extraction efficiency between the two phases and thus enhances the desulfurization efficiency.

[0049] Figure 3 E is for different initial sulfur contents, Figure 3 As can be seen from the figure, the ionic liquid extraction-electrocatalytic oxidation coupled electrochemical desulfurization scheme exhibits excellent removal performance in model oils with different sulfides and different initial sulfur contents. Example 2

[0050] (1) Dilute concentrated sulfuric acid (98% by mass) to a sulfuric acid solution (5% by mass), and measure 10 ml of the sulfuric acid solution into a jacketed beaker.

[0051] (2) Weigh out 0.1169 g of sodium chloride and dissolve it in 10 ml of sulfuric acid solution to prepare 0.2 mol / L simulated seawater.

[0052] (3) Take 6 ml of ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate). The ionic liquid used in the future will be 1-butyl-3-methylimidazolium tetrafluoroborate. At this time, the electrolyte is divided into two phases: the ionic liquid phase and the acidic salt water phase. A homogeneous electrolyte system has not yet been formed.

[0053] (4) The two phases in step 3 are stirred at 600 rpm for 10 minutes at 60°C to obtain a clear solution, which forms a homogeneous electrolyte phase. This system can continuously extract sulfides from the oil phase into the electrolyte phase. The extracted sulfides are oxidized at the anode into the high-value-added product DBTO2, maintaining the concentration gradient between the oil phase and the electrolyte phase, thereby significantly improving the desulfurization efficiency of electro-oxidation extraction coupling.

[0054] (5) Measure 10 ml of model oil (solute: DBT concentration of 400 ppm, internal standard: hexadecane concentration of 4000 ppm, solvent: dodecane) and make the ratio of its volume to the acidic saline system 1:1.

[0055] (6) Use a constant temperature water bath to control the reaction temperature at 30℃, use a magnetic stirrer to control the stirring speed at 500 rpm, and apply a constant current of 150 mA. Both the positive and negative electrodes are ordinary graphite electrodes, with the positive electrode being the site where the oxidation reaction occurs. Example 3

[0056] (1) Dilute concentrated sulfuric acid (98% by mass) to sulfuric acid solution (15% by mass), and measure 10 ml of sulfuric acid solution into a jacketed beaker.

[0057] (2) Weigh out 0.1169 g of sodium chloride and dissolve it in 10 ml of sulfuric acid solution to prepare 0.2 mol / L simulated seawater.

[0058] (3) Take 6 ml of ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate). The ionic liquid used in the future will be 1-butyl-3-methylimidazolium tetrafluoroborate. At this time, the electrolyte is divided into two phases: the ionic liquid phase and the acidic salt water phase. A homogeneous electrolyte system has not yet been formed.

[0059] (4) The two phases in step 3 are stirred at 600 rpm for 10 minutes at 60°C to obtain a clear solution, which forms a homogeneous electrolyte phase. This system can continuously extract sulfides from the oil phase into the electrolyte phase. The extracted sulfides are oxidized at the anode into the high-value-added product DBTO2, maintaining the concentration gradient between the oil phase and the electrolyte phase, thereby significantly improving the desulfurization efficiency of electro-oxidation extraction coupling.

[0060] (5) Measure 10 ml of model oil (solute: DBT concentration of 400 ppm, internal standard: hexadecane concentration of 4000 ppm, solvent: dodecane) and make the ratio of its volume to the acidic saline system 1:1.

[0061] (6) Use a constant temperature water bath to control the reaction temperature at 30℃, use a magnetic stirrer to control the stirring speed at 500 rpm, and apply a constant current of 150 mA. Both the positive and negative electrodes are ordinary graphite electrodes, with the positive electrode being the site where the oxidation reaction occurs. Example 4

[0062] (1) Dilute concentrated sulfuric acid (98% by mass) to a sulfuric acid solution (10% by mass), and measure 10 ml of the sulfuric acid solution into a jacketed beaker.

[0063] (2) Weigh out 0.0877 g of sodium chloride and dissolve it in 10 ml of sulfuric acid solution to prepare 0.15 mol / L simulated seawater.

[0064] (3) Take 6 ml of ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate). The ionic liquid used in the future will be 1-butyl-3-methylimidazolium tetrafluoroborate. At this time, the electrolyte is divided into two phases: the ionic liquid phase and the acidic salt water phase. A homogeneous electrolyte system has not yet been formed.

[0065] (4) The two phases in step 3 are stirred at 600 rpm for 10 minutes at 60°C to obtain a clear solution, which forms a homogeneous electrolyte phase. This system can continuously extract sulfides from the oil phase into the electrolyte phase. The extracted sulfides are oxidized at the anode into the high-value-added product DBTO2, maintaining the concentration gradient between the oil phase and the electrolyte phase, thereby significantly improving the desulfurization efficiency of electro-oxidation extraction coupling.

[0066] (5) Measure 10 ml of model oil (solute: DBT concentration of 400 ppm, internal standard: hexadecane concentration of 4000 ppm, solvent: dodecane) and make the ratio of its volume to the acidic saline system 1:1.

[0067] (6) Use a constant temperature water bath to control the reaction temperature at 30℃, use a magnetic stirrer to control the stirring speed at 500 rpm, and apply a constant current of 150 mA. Both the positive and negative electrodes are ordinary graphite electrodes, with the positive electrode being the site where the oxidation reaction occurs. Example 5

[0068] (1) Dilute concentrated sulfuric acid (98% by mass) to a sulfuric acid solution (10% by mass), and measure 10 ml of the sulfuric acid solution into a jacketed beaker.

[0069] (2) Weigh out 0.1023 g of sodium chloride and dissolve it in 10 ml of sulfuric acid solution to prepare 0.175 mol / L simulated seawater.

[0070] (3) Take 6 ml of ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate). The ionic liquid used in the future will be 1-butyl-3-methylimidazolium tetrafluoroborate. At this time, the electrolyte is divided into two phases: the ionic liquid phase and the acidic salt water phase. A homogeneous electrolyte system has not yet been formed.

[0071] (4) The two phases in step 3 are stirred at 600 rpm for 10 minutes at 60°C to obtain a clear solution, which forms a homogeneous electrolyte phase. This system can continuously extract sulfides from the oil phase into the electrolyte phase. The extracted sulfides are oxidized at the anode into the high-value-added product DBTO2, maintaining the concentration gradient between the oil phase and the electrolyte phase, thereby significantly improving the desulfurization efficiency of electro-oxidation extraction coupling.

[0072] (5) Measure 10 ml of model oil (solute: DBT concentration of 400 ppm, internal standard: hexadecane concentration of 4000 ppm, solvent: dodecane) and make the ratio of its volume to the acidic saline system 1:1.

[0073] (6) Use a constant temperature water bath to control the reaction temperature at 30℃, use a magnetic stirrer to control the stirring speed at 500 rpm, and apply a constant current of 150 mA. Both the positive and negative electrodes are ordinary graphite electrodes, with the positive electrode being the site where the oxidation reaction occurs. Example 6

[0074] (1) Dilute concentrated sulfuric acid (98% by mass) to a sulfuric acid solution (10% by mass), and measure 10 ml of the sulfuric acid solution into a jacketed beaker.

[0075] (2) Weigh out 0.1169 g of sodium chloride and dissolve it in 10 ml of sulfuric acid solution to prepare 0.2 mol / L simulated seawater.

[0076] (3) Take 4 ml of ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate). The ionic liquid used in the future will be 1-butyl-3-methylimidazolium tetrafluoroborate. At this time, the electrolyte is divided into two phases: the ionic liquid phase and the acidic salt water phase. A homogeneous electrolyte system has not yet been formed.

[0077] (4) The two phases in step 3 are stirred at 600 rpm for 10 minutes at 60°C to obtain a clear solution, which forms a homogeneous electrolyte phase. This system can continuously extract sulfides from the oil phase into the electrolyte phase. The extracted sulfides are oxidized at the anode into the high-value-added product DBTO2, maintaining the concentration gradient between the oil phase and the electrolyte phase, thereby significantly improving the desulfurization efficiency of electro-oxidation extraction coupling.

[0078] (5) Measure 10 ml of model oil (solute: DBT concentration of 400 ppm, internal standard: hexadecane concentration of 4000 ppm, solvent: dodecane) and make the ratio of its volume to the acidic saline system 1:1.

[0079] (6) Use a constant temperature water bath to control the reaction temperature at 30℃, use a magnetic stirrer to control the stirring speed at 500 rpm, and apply a constant current of 150 mA. Both the positive and negative electrodes are ordinary graphite electrodes, with the positive electrode being the site where the oxidation reaction occurs. Example 7

[0080] (1) Dilute concentrated sulfuric acid (98% by mass) to a sulfuric acid solution (10% by mass), and measure 10 ml of the sulfuric acid solution into a jacketed beaker.

[0081] (2) Weigh out 0.1169 g of sodium chloride and dissolve it in 10 ml of sulfuric acid solution to prepare 0.2 mol / L simulated seawater.

[0082] (3) Take 5 ml of ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate). The ionic liquid used in the future will be 1-butyl-3-methylimidazolium tetrafluoroborate. At this time, the electrolyte is divided into two phases: the ionic liquid phase and the acidic salt water phase. A homogeneous electrolyte system has not yet been formed.

[0083] (4) The two phases in step 3 are stirred at 600 rpm for 10 minutes at 60°C to obtain a clear solution, which forms a homogeneous electrolyte phase. This system can continuously extract sulfides from the oil phase into the electrolyte phase. The extracted sulfides are oxidized at the anode into the high-value-added product DBTO2, maintaining the concentration gradient between the oil phase and the electrolyte phase, thereby significantly improving the desulfurization efficiency of electro-oxidation extraction coupling.

[0084] (5) Measure 10 ml of model oil (solute: DBT concentration of 400 ppm, internal standard: hexadecane concentration of 4000 ppm, solvent: dodecane) and make the ratio of its volume to the acidic saline system 1:1.

[0085] (6) Use a constant temperature water bath to control the reaction temperature at 30℃, use a magnetic stirrer to control the stirring speed at 500 rpm, and apply a constant current of 150 mA. Both the positive and negative electrodes are ordinary graphite electrodes, with the positive electrode being the site where the oxidation reaction occurs.

[0086] Examples 8-13

[0087] The acidic brine electrolyte containing ionic liquids obtained in Examples 1-7 was applied to an extraction-electrocatalytic oxidation coupled process to remove sulfides from oil products. The following are the components of the experimental apparatus for simulating diesel fuel and desulfurization:

[0088] The model oil was prepared by dissolving dibenzothiophene (DBT), 4-methyldibenzothiophene (4-MDBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT) in n-dodecane, with n-hexadecane added as an internal standard.

[0089] Take 10 mL of model oil and place it in a jacketed beaker. Add the acidic saline electrolyte containing ionic liquid (10 mL acidic saline + 6 mL ionic liquid) prepared in the example, and place the jacketed beaker in a constant temperature water bath at 30°C. Connect the graphite electrode and apply a constant current of 150 mA using a constant current power supply, while simultaneously turning on the magnetic stirrer at a speed of 500 rpm. During the reaction, the sulfur content in the oil is quantitatively detected using gas chromatography, and the desulfurization rate is calculated according to the following formula.

[0090]

[0091] The experimental results are shown in Table 1.

[0092] Table 1

[0093] .

[0094] As shown in Table 1, the novel ionic liquid electro-oxidative extraction coupling method used in all embodiments exhibits excellent removal efficiency for sulfides in the model oil. Furthermore, this method can remove different sulfides under the same conditions, with removal efficiencies of DBT > 4-MDBT > 4,6-DMDBT.

[0095] This invention provides a novel approach and method for desulfurization using ionic liquid extraction coupled with electrocatalytic oxidation. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. A method for desulfurization coupled with ionic liquid extraction and electrocatalytic oxidation, characterized in that, Includes the following steps: (1) Prepare an aqueous solution of sulfuric acid; (2) Dissolve the soluble metal chloride salt in the sulfuric acid aqueous solution obtained in step (1) to prepare an acidic salt electrolyte; (3) Add the ionic liquid to the acidic brine electrolyte in step (2) and mix thoroughly to form a homogeneous acidic brine electrolyte containing the ionic liquid; (4) Add the fuel oil to be desulfurized to the acidic brine electrolyte containing ionic liquid in step (3), and electrolyze it under a constant current of DC power supply until the sulfides in the fuel oil are completely removed. (5) Separate fuel oil and electrolyte to achieve complete removal of sulfides in the oil phase and convert them into desulfurization product DBTO2; In step (2), the soluble metal chloride salt is selected from any one of KCl, NaCl, MgCl2, and CaCl2; the concentration of the soluble metal chloride salt in the obtained acidic brine electrolyte is 0.15~0.2 mol / L; In step (3), the ionic liquid is any one of [Bmim]BF4, [Bmim]PF6, [Omim]BF4, and [Omim]PF6; In step (3), the ionic liquid and the acidic salt electrolyte are mixed at a volume ratio of 1 to 5:

5.

2. The process for coupling of electro-catalytic oxidation with ionic liquid extraction desulfurization according to claim 1, characterized in that, In step (1), the mass fraction of the sulfuric acid aqueous solution is 5-15%.

3. The process for coupling of electro-catalytic oxidation with ionic liquid extraction desulfurization according to claim 1, characterized in that, In step (3), the mixing temperature is controlled at 40~80℃, the time is 5~10 minutes, and the stirring speed is 400~800 rpm.

4. The process for coupling of electro-catalytic oxidation with ionic liquid extraction desulfurization according to claim 1, characterized in that, In step (4), the fuel oil to be desulfurized includes any one of DBT, 4-MDBT, and 4,6-DMDBT.

5. The process for coupling of electro-catalytic oxidation with ionic liquid extraction desulfurization according to claim 1, characterized in that, In step (4), the ionic liquid acidic brine electrolyte is mixed with the fuel oil to be desulfurized at a volume ratio of 1:1 to 3.

6. The method for desulfurization coupled with ionic liquid extraction and electrocatalytic oxidation according to claim 1, characterized in that, In step (4), the current is 100~200 mA and the electrolysis reaction time is 15~20 min.

7. The method for desulfurization coupled with ionic liquid extraction and electrocatalytic oxidation according to claim 1, characterized in that, In step (5), fuel oil and electrolyte are separated by a liquid separation method.

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