Novel ionic liquid extraction and electrocatalytic oxidation coupled desulfurization method

Abstract

The invention discloses a novel ionic liquid extraction and electrocatalytic oxidation coupled desulfurization method, and the adopted ionic liquid serves as a catalyst to accelerate an oxidation desulfurization reaction on one hand, and also serves as an extraction agent to promote rapid extraction of sulfide on the other hand. According to the innovative method, the desulfurization speed and efficiency are greatly improved, and compared with a traditional oxidation desulfurization technology, the reaction rate is obviously improved by about 20 times. Besides, simulated seawater (hereinafter referred to as acidic brine) is adopted as an electrolyte, so that the generation of an in-situ oxidant is realized, and ClO <-> with catalytic oxidation performance is generated by effectively utilizing the Cl <-> oxidation reaction of the anode. The innovation not only improves the efficiency of electrolyzing sea water to produce hydrogen, but also avoids low efficiency and potential safety hazards caused by the introduction of a traditional oxidant. Considering that seawater resources are rich and low in cost, the technology is suitable for being implemented around an oil refinery, and an oxidizing agent does not need to be additionally added, so that the cost of ultra-deep desulfurization is reduced, and the safety of the desulfurization process is enhanced.

Description

Technical Field

[0001] The invention belongs to the technical field of electrochemical desulfurization in petrochemical industry, and in particular relates to a novel ionic liquid extraction electrocatalytic oxidation coupled desulfurization method. Background Art

[0002] With the increasing global requirements for environmental governance and the deepening of energy transformation, the problem of sulfides in fossil fuels such as diesel has become particularly prominent. The acid rain and PM2.5 pollution produced by the combustion of these sulfides pose a serious threat to ecological security and human health. In order to meet this challenge, many countries and regions, including China, the United States, and the European Union, have introduced strict regulations to limit the concentration of sulfides in fuel to no more than 10 μg / g. However, with the deepening of oil production, the quality of crude oil has gradually declined. For example, the sulfur content in Venezuelan crude oil exceeds 5.5 wt.%, which poses a huge challenge to the desulfurization process. Traditional hydrodesulfurization (HDS) technology is not efficient in treating aromatic sulfides, and as the quality of crude oil decreases, the required temperature and pressure increase significantly, resulting in a significant increase in energy consumption and carbon emissions. Therefore, researchers have developed a variety of non-hydrodesulfurization technologies, such as adsorption desulfurization (ADS), extractive desulfurization (EDS), oxidative desulfurization (ODS) and biological desulfurization (BDS), among which oxidative desulfurization (ODS) has attracted much 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, but this process requires the addition of expensive and low-utilization oxidants such as hydrogen peroxide and organic peroxides. Therefore, it is urgent to develop new ODS desulfurization processes. At the same time, in order to achieve large-scale water electrolysis to produce hydrogen, many studies have reported methods for electrolyzing seawater to produce hydrogen. In the process of seawater electrolysis, the Cl at the anode - Oxidation produces ClO - It has excellent catalytic oxidation performance and can be used to catalyze the oxidative desulfurization of aromatic sulfides and construct an electrocatalytic oxidation desulfurization system (E-ODS). This method can not only efficiently utilize the low-value Cl- oxidation reaction, but also make the process of hydrogen production by electrolysis of seawater not limited by voltage, greatly improving the efficiency of hydrogen production. By controlling the voltage of the applied electric field, the electrochemical catalytic oxidation performance can be controlled to obtain better ODS performance. In addition, since most refineries are built on the seashore, the abundant seawater resources are conducive to the construction of the E-ODS system, reducing the cost of desulfurization and improving safety. At the same time, the cathode efficiently produces hydrogen, and the produced hydrogen can be directly used in the refining process, reducing the cost of refining enterprises.

[0004] Although the E-ODS system is still in its early stages of research, it shows great potential in terms of 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. In addition, the double layer in the E-ODS process hinders electron transfer and reduces efficiency. Therefore, it is crucial to enhance the mass transfer efficiency and charge transfer efficiency of the E-ODS system and break through the mass transfer and diffusion resistance and double layer resistance to achieve efficient oxidative desulfurization. Summary of the invention

[0005] Purpose of the invention: The technical problem to be solved by the present invention is to address the shortcomings of the existing oxidative desulfurization technology, especially the ClO generated in the process of electrolysis of seawater to produce hydrogen. - In order to solve the problem of utilizing materials such as sulfide, an electrochemical desulfurization method based on ionic liquid extraction-electrocatalytic oxidation coupling is provided to shorten the time of oxidation desulfurization and improve the oxidation efficiency.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows: A novel ionic liquid extraction electrocatalytic oxidation coupled desulfurization method comprises the following steps: (1) Prepare sulfuric acid aqueous solution; (2) dissolving a soluble metal chloride salt in the aqueous sulfuric acid solution obtained in step (1) to prepare an acidic brine electrolyte; (3) adding the ionic liquid to the acidic salt water electrolyte in step (2) and mixing and stirring thoroughly to form a uniform acidic salt water electrolyte containing the ionic liquid; (4) adding the fuel to be desulfurized to the acidic brine electrolyte containing ionic liquid in step (3), and electrolyzing the fuel under a constant current of a DC power supply until the sulfide in the fuel is completely removed; (5) Separate the fuel and electrolyte to completely remove the sulfides in the oil phase and convert them into the desulfurization product DBTO2.

[0007] Specifically, in step (1), the mass fraction of the aqueous sulfuric acid solution is 5-15%.

[0008] Specifically, in step (2), the soluble metal chloride salt is selected from any one of the common chloride salts in seawater, such as KCl, NaCl, MgCl2, CaCl2, etc.; the concentration of the soluble metal chloride salt in the obtained acidic salt water electrolyte is 0.15~0.2 mol / L.

[0009] 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, [Omim]PF6, etc.

[0010] Specifically, in step (3), the ionic liquid and the acidic salt water electrolyte are mixed in a volume ratio of 1 to 5:5.

[0011] Specifically, in step (3), the mixing temperature is controlled at 40-80°C, the time is 5-10 minutes, and the stirring speed is 400-800 rpm.

[0012] Specifically, in step (4), the fuel to be desulfurized includes any one of DBT, 4-MDBT, and 4,6-DMDBT.

[0013] Specifically, in step (4), the ionic liquid acidic brine electrolyte is mixed with the fuel to be desulfurized in a volume ratio of 1:1 to 3.

[0014] Specifically, in step (4), the current is 100-200 mA, and the electrolysis reaction time is 15-20 min.

[0015] Specifically, in step (5), the fuel and the electrolyte are separated by a liquid separation method.

[0016] In recent years, in order to achieve large-scale water electrolysis to produce hydrogen, many studies have reported methods for producing hydrogen by electrolyzing seawater. However, in the process of seawater electrolysis, the anode is sensitive to Cl - Oxidation produces Cl2 or ClO - It is generally considered that it is not conducive to the large-scale application of water electrolysis to produce hydrogen. However, the present invention found that ClO - It has excellent catalytic oxidation performance in the oxidative desulfurization (ODS) process. Therefore, the present invention proposes an electrocatalytic oxidative desulfurization system (E-ODS), which makes full use of the low-value Cl - Oxidation reaction, in situ generation of oxidants, and used to catalyze the oxidative desulfurization of aromatic sulfides, thereby achieving low Cl - The oxidation reaction is efficiently utilized, and the process of hydrogen production by electrolysis of seawater is no longer limited by voltage, and can be carried out under high voltage and high current, greatly improving the efficiency of hydrogen production by electrolysis of seawater. By controlling the voltage of the applied electric field, the electrochemical catalytic oxidation performance can be controlled to obtain better ODS performance. On the other hand, oil refineries are mostly built on the seashore, and there are usually abundant seawater resources around them, which is conducive to the construction of an E-ODS system. The present invention not only does not require the addition of an oxidant, reduces the cost of ultra-deep desulfurization of fuel oil, and improves the safety of desulfurization, but also because the anode side reaction is fully utilized, the cathode can efficiently produce hydrogen under high voltage and high current, and the produced hydrogen can be directly used for hydrofining in the oil refining process, avoiding additional hydrogen storage and transportation, and is expected to significantly reduce the cost of oil refining enterprises.

[0017] By introducing the ionic liquid [Bmim]BF4 as an extractant and reaction medium in 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 double electric layer at the interface of the electrode and the electrolyte through ion balance, enhance electron transfer, and improve desulfurization performance. Ionic liquids have attracted widespread attention due to their excellent solubility, high chemical and thermal stability, excellent conductivity, and almost no vapor pressure. In the ionic liquid-based extraction-coupled catalytic oxidation desulfurization system, the sulfide in the fuel is extracted and enriched by the ionic liquid, and further catalytic oxidation reactions are carried out in the ionic liquid phase, breaking the extraction equilibrium and achieving deep desulfurization. Constructing an innovative ionic liquid acidic brine electrolyte, which is proven to be a feasible and creative method in the present invention, can avoid the process of sulfide polymerization and dissolution, and improve the efficiency of deep desulfurization. Beneficial Effects

[0018] (1) The acidic salt water electrolyte used in the present invention, on the one hand, generates oxidants in situ, effectively avoiding the safety risks, low efficiency and oil peroxidation problems caused by the continuous addition of oxidants in the later stage; on the other hand, due to the abundant seawater resources, low cost, mild reaction conditions, and 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 be started instantly, and the reaction rate is increased by about 20 times compared with traditional oxidative desulfurization.

[0019] (2) The present invention utilizes the extraction performance of ionic liquids for sulfides in oil products, extracts the high value-added product DBTO2 generated by in-situ oxidation into the electrolyte, and obtains an oil product completely free of sulfides and an electrolyte containing DBTO2, which can be separated by a liquid separation method.

[0020] (3) The ionic liquid extraction electrocatalytic oxidation coupled desulfurization method designed in the present invention has wide applicability and can effectively remove different types of sulfides, such as DBT, 4-MDBT, 4,6-DMDBT, etc.

[0021] (4) The synthesis method adopted in the present invention is simple to operate, green and environmentally friendly, and has good application prospects and market potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become more clear.

[0023] Figure 1 This is a schematic diagram of the novel ionic liquid extraction-electrocatalytic oxidation coupled desulfurization process of the present invention.

[0024] Figure 2The effect of electrolyte composition on DBT activity in fuel in this experimental method is demonstrated.

[0025] Figure 3 The effect of reaction conditions on DBT activity in fuel in this experimental method is demonstrated. DETAILED DESCRIPTION

[0026] The present invention can be better understood with reference to the following examples. Example 1

[0027] (1) Dilute concentrated sulfuric acid (mass fraction 98%) to a sulfuric acid solution (mass fraction 10%) and place 10 ml of the sulfuric acid solution in a jacketed beaker.

[0028] (2) Weigh 0.1169 g of sodium chloride and dissolve it in 10 ml of sulfuric acid solution to prepare 0.2 mol / L simulated seawater.

[0029] (3) Take 6 ml of ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate). The ionic liquid used subsequently is 1-butyl-3-methylimidazolium tetrafluoroborate. At this time, the electrolyte is divided into two phases: the ionic liquid phase and the acidic brine phase. A uniform electrolyte system has not yet been formed.

[0030] (4) The two phases in step 3 are stirred at 600 rpm for 10 minutes at 60°C to obtain a clear solution, and a homogeneous electrolyte phase is constructed. The system can continuously extract sulfides from the oil phase into the electrolyte phase, and the extracted sulfides are oxidized at the anode to form high value-added products DBTO2, maintaining the concentration gradient between the oil phase and the electrolyte phase, thereby significantly improving the desulfurization efficiency of electro-oxidation extraction coupling.

[0031] (5) Take 10 ml of model oil (solute: DBT concentration is 400 ppm, internal standard: hexadecane concentration is 4000 ppm, solvent: dodecane) and mix them in a 1:1 ratio with the acidic brine system.

[0032] (6) The reaction temperature was controlled at 30°C using a constant temperature water bath, the stirring speed was controlled at 500 rpm using a magnetic stirrer, and a constant current power supply applied a working current of 150 mA. Both the positive and negative electrodes were ordinary graphite electrodes, with the positive electrode being the site where the oxidation reaction occurred.

[0033] Figure 1 This is a schematic diagram of the novel ionic liquid extraction-electrocatalytic oxidation coupled desulfurization process of the present invention.

[0034] Figure 2 The effect of electrolyte variables on DBT activity in fuels in this experimental method is demonstrated.

[0035] in: Figure 2 Figure A shows the effect of adjusting the H2SO4 concentration on the activity of DBT in fuel. It can be seen from the figure that excessive sulfuric acid concentration is prone to corrode graphite electrodes, so an appropriate concentration of sulfuric acid should be selected.

[0036] Figure 2 B shows the effect of adjusting the NaCl concentration in the electrolyte on the DBT activity in the fuel. It can be seen from the figure that after adding NaCl, ClO is generated at the anode because more oxidation units are provided and the conductivity of the solution is improved. - The higher the concentration, the more oxidation units provided and the higher the desulfurization rate.

[0037] Figure 2 C shows the effect of different ionic liquid types on the activity of DBT in fuel. It can be seen from the figure that only [Bmim]BF4 can be miscible with water in any proportion to form a homogeneous system of ionic liquid acidic brine electrolyte, which makes NaCl dissolve better in the electrolyte, the electrolyte is evenly distributed, and the ion mass transfer is enhanced, thus having good electrochemical desulfurization performance.

[0038] Figure 2 D shows the effect of the amount of ionic liquid in the electrolyte on the activity of DBT in the fuel. It can be seen from the figure that the extraction effect brought by the ionic liquid plays a key role in the ionic liquid extraction-electrocatalytic oxidation coupled electrochemical desulfurization of this scheme.

[0039] Figure 3 The effect of oil product variables in this experimental method on DBT activity in fuel is demonstrated.

[0040] in: Figure 3 A shows the effect of electrolyte at different temperatures on the activity of DBT in fuel. It can be seen from the figure that the scheme can be carried out at room temperature, and different temperatures have little effect on the ionic liquid extraction-electrocatalytic oxidation coupled electrochemical desulfurization. Figure 3 B shows the kinetic fitting diagram at different temperatures. It can be seen from the figure that the scheme 0-20 min is under pseudo-first-order kinetics.

[0041] Figure 3 Figure C shows the effect of electrolyte on DBT activity in fuel under different constant currents. It can be seen from the figure that when the constant current exceeds a certain value, the desulfurization rate decreases despite the increase in current, which indicates that a higher applied current may break down the electrode and cannot bring higher desulfurization efficiency.

[0042] Figure 3D shows the effect of electrolyte on DBT activity in fuel at different stirring speeds. It can be seen from the figure that with the increase of stirring rate, 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.

[0043] Figure 3 EFor different initial sulfur contents, Figure 3 F For different sulfides, it can be seen from the figure that the ionic liquid extraction-electrocatalytic oxidation coupled electrochemical desulfurization of this scheme shows excellent removal performance in model oils with different sulfides and different initial sulfur contents. Example 2

[0044] (1) Dilute concentrated sulfuric acid (mass fraction 98%) to a sulfuric acid solution (mass fraction 5%) and place 10 ml of the sulfuric acid solution in a jacketed beaker.

[0045] (2) Weigh 0.1169 g of sodium chloride and dissolve it in 10 ml of sulfuric acid solution to prepare 0.2 mol / L simulated seawater.

[0046] (3) Take 6 ml of ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate). The ionic liquid used subsequently is 1-butyl-3-methylimidazolium tetrafluoroborate. At this time, the electrolyte is divided into two phases: the ionic liquid phase and the acidic brine phase. A uniform electrolyte system has not yet been formed.

[0047] (4) The two phases in step 3 are stirred at 600 rpm for 10 minutes at 60°C to obtain a clear solution, and a homogeneous electrolyte phase is constructed. The system can continuously extract sulfides from the oil phase into the electrolyte phase, and the extracted sulfides are oxidized at the anode to form high value-added products DBTO2, maintaining the concentration gradient between the oil phase and the electrolyte phase, thereby significantly improving the desulfurization efficiency of electro-oxidation extraction coupling.

[0048] (5) Take 10 ml of model oil (solute: DBT concentration is 400 ppm, internal standard: hexadecane concentration is 4000 ppm, solvent: dodecane) and mix them in a 1:1 ratio with the acidic brine system.

[0049] (6) The reaction temperature was controlled at 30°C using a constant temperature water bath, the stirring speed was controlled at 500 rpm using a magnetic stirrer, and a constant current power supply applied a working current of 150 mA. Both the positive and negative electrodes were ordinary graphite electrodes, with the positive electrode being the site where the oxidation reaction occurred. Example 3

[0050] (1) Dilute concentrated sulfuric acid (mass fraction 98%) to a sulfuric acid solution (mass fraction 15%) and place 10 ml of the sulfuric acid solution in a jacketed beaker.

[0051] (2) Weigh 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 subsequently is 1-butyl-3-methylimidazolium tetrafluoroborate. At this time, the electrolyte is divided into two phases: the ionic liquid phase and the acidic brine phase. A uniform 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, and a homogeneous electrolyte phase is constructed. The system can continuously extract sulfides from the oil phase into the electrolyte phase, and the extracted sulfides are oxidized at the anode to form high value-added products 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) Take 10 ml of model oil (solute: DBT concentration is 400 ppm, internal standard: hexadecane concentration is 4000 ppm, solvent: dodecane) and mix them in a 1:1 ratio with the acidic brine system.

[0055] (6) The reaction temperature was controlled at 30°C using a constant temperature water bath, the stirring speed was controlled at 500 rpm using a magnetic stirrer, and a constant current power supply applied a working current of 150 mA. Both the positive and negative electrodes were ordinary graphite electrodes, with the positive electrode being the site where the oxidation reaction occurred. Example 4

[0056] (1) Dilute concentrated sulfuric acid (mass fraction 98%) to a sulfuric acid solution (mass fraction 10%) and place 10 ml of the sulfuric acid solution in a jacketed beaker.

[0057] (2) Weigh 0.0877 g of sodium chloride and dissolve it in 10 ml of sulfuric acid solution to prepare 0.15 mol / L simulated seawater.

[0058] (3) Take 6 ml of ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate). The ionic liquid used subsequently is 1-butyl-3-methylimidazolium tetrafluoroborate. At this time, the electrolyte is divided into two phases: the ionic liquid phase and the acidic brine phase. A uniform 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, and a homogeneous electrolyte phase is constructed. The system can continuously extract sulfides from the oil phase into the electrolyte phase, and the extracted sulfides are oxidized at the anode to form high value-added products 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) Take 10 ml of model oil (solute: DBT concentration is 400 ppm, internal standard: hexadecane concentration is 4000 ppm, solvent: dodecane) and mix them in a 1:1 ratio with the acidic brine system.

[0061] (6) The reaction temperature was controlled at 30°C using a constant temperature water bath, the stirring speed was controlled at 500 rpm using a magnetic stirrer, and a constant current power supply applied a working current of 150 mA. Both the positive and negative electrodes were ordinary graphite electrodes, with the positive electrode being the site where the oxidation reaction occurred. Example 5

[0062] (1) Dilute concentrated sulfuric acid (mass fraction 98%) to a sulfuric acid solution (mass fraction 10%) and place 10 ml of the sulfuric acid solution in a jacketed beaker.

[0063] (2) Weigh 0.1023 g of sodium chloride and dissolve it in 10 ml of sulfuric acid solution to prepare 0.175 mol / L simulated seawater.

[0064] (3) Take 6 ml of ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate). The ionic liquid used subsequently is 1-butyl-3-methylimidazolium tetrafluoroborate. At this time, the electrolyte is divided into two phases: the ionic liquid phase and the acidic brine phase. A uniform 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, and a homogeneous electrolyte phase is constructed. The system can continuously extract sulfides from the oil phase into the electrolyte phase, and the extracted sulfides are oxidized at the anode to form high value-added products 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) Take 10 ml of model oil (solute: DBT concentration is 400 ppm, internal standard: hexadecane concentration is 4000 ppm, solvent: dodecane) and mix them in a 1:1 ratio with the acidic brine system.

[0067] (6) The reaction temperature was controlled at 30°C using a constant temperature water bath, the stirring speed was controlled at 500 rpm using a magnetic stirrer, and a constant current power supply applied a working current of 150 mA. Both the positive and negative electrodes were ordinary graphite electrodes, with the positive electrode being the site where the oxidation reaction occurred. Example 6

[0068] (1) Dilute concentrated sulfuric acid (mass fraction 98%) to a sulfuric acid solution (mass fraction 10%) and place 10 ml of the sulfuric acid solution in a jacketed beaker.

[0069] (2) Weigh 0.1169 g of sodium chloride and dissolve it in 10 ml of sulfuric acid solution to prepare 0.2 mol / L simulated seawater.

[0070] (3) Take 4 ml of ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate). The ionic liquid used subsequently is 1-butyl-3-methylimidazolium tetrafluoroborate. At this time, the electrolyte is divided into two phases: the ionic liquid phase and the acidic brine phase. A uniform 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, and a homogeneous electrolyte phase is constructed. The system can continuously extract sulfides from the oil phase into the electrolyte phase, and the extracted sulfides are oxidized at the anode to form high value-added products 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) Take 10 ml of model oil (solute: DBT concentration is 400 ppm, internal standard: hexadecane concentration is 4000 ppm, solvent: dodecane) and mix them in a 1:1 ratio with the acidic brine system.

[0073] (6) The reaction temperature was controlled at 30°C using a constant temperature water bath, the stirring speed was controlled at 500 rpm using a magnetic stirrer, and a constant current power supply applied a working current of 150 mA. Both the positive and negative electrodes were ordinary graphite electrodes, with the positive electrode being the site where the oxidation reaction occurred. Example 7

[0074] (1) Dilute concentrated sulfuric acid (mass fraction 98%) to a sulfuric acid solution (mass fraction 10%) and place 10 ml of the sulfuric acid solution in a jacketed beaker.

[0075] (2) Weigh 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 5 ml of ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate). The ionic liquid used subsequently is 1-butyl-3-methylimidazolium tetrafluoroborate. At this time, the electrolyte is divided into two phases: the ionic liquid phase and the acidic brine phase. A uniform 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, and a homogeneous electrolyte phase is constructed. The system can continuously extract sulfides from the oil phase into the electrolyte phase, and the extracted sulfides are oxidized at the anode to form high value-added products 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) Take 10 ml of model oil (solute: DBT concentration is 400 ppm, internal standard: hexadecane concentration is 4000 ppm, solvent: dodecane) and mix them in a 1:1 ratio with the acidic brine system.

[0079] (6) The reaction temperature was controlled at 30°C using a constant temperature water bath, the stirring speed was controlled at 500 rpm using a magnetic stirrer, and a constant current power supply applied a working current of 150 mA. Both the positive and negative electrodes were ordinary graphite electrodes, with the positive electrode being the site where the oxidation reaction occurred. Embodiments 8 to 13

[0080] The acidic brine electrolyte containing ionic liquid obtained in Examples 1-7 was applied to the extraction-electrocatalytic oxidation coupling process to remove sulfides from oil products. The following are the types of oil products simulating diesel and the components of the oxidation desulfurization experimental device: The model oil was prepared by dissolving dibenzothiophene (DBT), 4-methyldibenzothiophene (4-MDBT), and 4,6-dimethyldibenzothiophene (4,6-DMDBT) in n-dodecane, respectively, and n-hexadecane was added as an internal standard.

[0081] Take 10 mL of model oil and place it in a jacketed beaker, add the acidic brine electrolyte containing ionic liquid prepared in the example (10 ml acidic brine + 6 mL ionic liquid), and place the jacketed beaker in a constant temperature water bath at 30°C. Connect a graphite electrode, use a constant current power supply to apply a constant current of 150 mA, and turn on the magnetic stirrer to stir at a speed of 500 rpm. During the reaction, the sulfur content in the oil is quantitatively detected by gas chromatograph, and the desulfurization rate is calculated according to the following formula.

[0082] The experimental results are shown in Table 1.

[0083] Table 1

[0084] It can be seen from Table 1 that the novel ionic liquid electro-oxidation extraction coupling used in all embodiments has a good removal effect on the sulfides in the model oil. Among them, this scheme can remove different sulfides under the same conditions, and the removal efficiency DBT>4-MDBT>4,6-DMDBT.

[0085] The present invention provides a new method and method for ionic liquid extraction electrocatalytic oxidation coupled desulfurization. There are many methods and ways to implement the technical solution. The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention. All components not specified in this embodiment can be implemented by existing technologies.

Claims

1. A novel ionic liquid extraction electrocatalytic oxidation coupled desulfurization method, characterized in that: The steps include: (1) Prepare sulfuric acid aqueous solution; (2) dissolving a soluble metal chloride salt in the aqueous sulfuric acid solution obtained in step (1) to prepare an acidic brine electrolyte; (3) adding the ionic liquid to the acidic salt water electrolyte in step (2) and mixing and stirring thoroughly to form a uniform acidic salt water electrolyte containing the ionic liquid; (4) adding the fuel to be desulfurized to the acidic brine electrolyte containing ionic liquid in step (3), and electrolyzing the fuel under a constant current of a DC power supply until the sulfide in the fuel is completely removed; (5) Separate the fuel and electrolyte to completely remove the sulfides in the oil phase and convert them into the desulfurization product DBTO2.

2. The novel ionic liquid extraction electrocatalytic oxidation coupled desulfurization method according to claim 1 is characterized in that: In step (1), the mass fraction of the aqueous sulfuric acid solution is 5-15%.

3. The novel ionic liquid extraction electrocatalytic oxidation coupled desulfurization method according to claim 1 is characterized in that: In step (2), the soluble metal chloride salt is selected from any one of KCl, NaCl, MgCl2, and CaCl2; and the concentration of the soluble metal chloride salt in the obtained acidic salt water electrolyte is 0.15~0.2 mol / L.

4. The novel ionic liquid extraction electrocatalytic oxidation coupled desulfurization method according to claim 1 is characterized in that: In step (3), the ionic liquid is any one of [Bmim]BF4, [Bmim]PF6, [Omim]BF4, and [Omim]PF6.

5. The novel ionic liquid extraction electrocatalytic oxidation coupled desulfurization method according to claim 1 is characterized in that: In step (3), the ionic liquid and the acidic salt water electrolyte are mixed in a volume ratio of 1 to 5:

5.

6. The novel ionic liquid extraction electrocatalytic oxidation coupled desulfurization method according to claim 1 is characterized in that: In step (3), the mixing and stirring temperature is controlled at 40-80°C, the time is 5-10 minutes, and the stirring speed is 400-800 rpm.

7. The novel ionic liquid extraction electrocatalytic oxidation coupled desulfurization method according to claim 1 is characterized in that: In step (4), the fuel to be desulfurized includes any one of DBT, 4-MDBT, and 4,6-DMDBT.

8. The novel ionic liquid extraction electrocatalytic oxidation coupled desulfurization method according to claim 1 is characterized in that: In step (4), the ionic liquid acidic brine electrolyte is mixed with the fuel to be desulfurized in a volume ratio of 1:1 to 3.

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

10. The novel ionic liquid extraction electrocatalytic oxidation coupled desulfurization method according to claim 1 is characterized in that: In step (5), the fuel and the electrolyte are separated by a liquid separation method.

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