Process for the desulfurization of bitumen

Abstract

This invention discloses a method for desulfurizing asphalt, comprising: mixing asphalt with a solvent to obtain a mixed oil; heating the mixed oil; flash-evaporating the heated mixed oil in an oxidation tower, and introducing a gaseous oxidant for reaction; after the reaction, the solvent and unreacted gaseous oxidant enter the light phase and escape from the top of the tower; the asphalt enters the heavy phase and is discharged from the bottom of the tower; the asphalt enters a washing tank, and desulfurization liquid is introduced, mixed, and stirred; the sulfur-rich desulfurization liquid is discharged from the top of the washing tank, and the desulfurized asphalt is discharged from the bottom of the washing tank. The method of this invention uses asphalt and solvent to prepare a mixed oil, which, after heating, is atomized by flash evaporation. The mixed oil forms small droplets or liquid films, which fully contact the gaseous oxidant, accelerating the gas-liquid reaction. This converts the water-insoluble sulfur in the asphalt into soluble sulfoxides or sulfones, etc., and removes the sulfur through washing with the desulfurization liquid and oil-water separation, effectively reducing the sulfur content in the asphalt and obtaining high-quality asphalt suitable for producing needle coke, carbon fiber, and other carbon products.

Description

Technical Field

[0001] This invention belongs to the field of chemical engineering, and more specifically, this invention relates to a method for desulfurizing asphalt. Background Technology

[0002] The performance of lithium-ion battery anode materials or graphite electrodes is closely related to the quality of needle coke, which in turn is related to the sulfur content in the raw material pitch. During the formation of needle coke in the mid-stage of pitch mesophase transformation, sulfur, as a heteroatom, causes extensive cross-linking of aromatic layer molecules, increasing the viscosity of the system and forming a fine mosaic structure, thus affecting the quality of the needle coke. Furthermore, sulfur rapidly escapes from carbon materials during the graphitization stage, leading to expansion and even cracking of the carbon materials. It has been reported that when the sulfur content in pitch is less than 0.5 wt%, cracking caused by sulfur escape during the graphitization stage can be effectively avoided. However, the sulfur content in pitch is generally above 0.6%, and in some cases even reaches 1.2 wt%. Therefore, the removal of sulfur from pitch is crucial for producing high-quality needle coke, and thus, there is an urgent need to find an effective method for pitch desulfurization. Summary of the Invention

[0003] This invention is based on the inventors' findings and understanding of the following facts and problems: Sulfur in asphalt mainly exists in the form of organosulfur compounds, including aliphatic sulfur, thiophene sulfur, and sulfoxide sulfur. Hydrogenation and oxidation methods have been used by researchers for the desulfurization of asphalt. Generally, the high-temperature and harsh conditions required by hydrogenation can break the condensed fused-ring aromatic structure, thereby removing sulfur atoms. However, fused-ring aromatics determine the coking activity of asphalt, and the destruction of the fused-ring aromatic structure during hydrogenation is detrimental to the production of needle coke. Oxidation requires milder conditions than hydrogenation, and organosulfur compounds in asphalt can be oxidized into more polar oxidation products, such as sulfoxides and sulfones, and removed. However, currently used oxidation methods have some limitations, including the need for ultrasonic treatment or the need to grind the raw materials into fine powder, which increases the difficulty of raw material processing, energy consumption, and production costs. Therefore, it is necessary to develop an efficient method for the oxidative desulfurization of asphalt.

[0004] This invention aims to at least partially solve one of the technical problems in related technologies. To this end, embodiments of this invention propose a method for asphalt desulfurization. Asphalt is mixed with a solvent to form a mixed oil. After heating, the mixed oil is atomized through flash evaporation, forming small droplets or liquid films in an oxidation tower. This allows for sufficient contact with the gaseous oxidant, accelerating the gas-liquid reaction and transforming water-insoluble structures such as thiophene sulfur in the asphalt into soluble sulfoxide or sulfone structures. Sulfur is then removed through desulfurization liquid washing and oil-water separation, effectively reducing the sulfur content in the asphalt and yielding high-quality asphalt suitable for producing needle coke, carbon fiber, and other carbon products.

[0005] An embodiment of the present invention provides a method for asphalt desulfurization, comprising the following steps:

[0006] (1) Mix asphalt with a solvent to obtain a mixed oil;

[0007] (2) Heat the mixed oil;

[0008] (3) The heated mixed oil enters the oxidation tower for flash evaporation, and gaseous oxidant is introduced to react; after the reaction, the solvent and unreacted gaseous oxidant enter the light phase and escape from the top of the tower; the asphalt enters the heavy phase and is discharged from the bottom of the tower.

[0009] (4) The discharged asphalt enters the washing tank, and desulfurization liquid is introduced, mixed and stirred; the sulfur-rich desulfurization liquid is discharged from the top of the washing tank, and the desulfurized asphalt is discharged from the bottom of the washing tank.

[0010] The advantages and technical effects of the asphalt desulfurization method in this invention are as follows: A mixed oil is prepared by mixing asphalt and solvent. After heating, the mixed oil is atomized through flash evaporation. The mixed oil forms small droplets or liquid films in the oxidation tower, allowing for full contact with the gaseous oxidant and accelerating the gas-liquid reaction. This transforms water-insoluble structures such as thiophene sulfur in the asphalt into soluble sulfoxide or sulfone structures. Sulfur is removed through desulfurization liquid washing and oil-water separation, effectively reducing the sulfur content in the asphalt and yielding high-quality asphalt suitable for producing needle coke, carbon fiber, and other carbon products. In this invention, the gas-liquid reaction after mixing asphalt and solvent avoids the pretreatment process of asphalt pulverization, reducing the difficulty of raw material processing, energy consumption, and production costs. Compared to catalytic hydrogenation methods, the oxidation method of this invention requires milder, more efficient, and more environmentally friendly conditions. Unreacted gaseous oxidant and solvent can be recycled and reused. It is simple to operate, suitable for large-scale continuous production, and has broad application prospects in fields such as coal chemical industry.

[0011] In some embodiments, in step (1), the asphalt includes at least one of coal tar pitch, petroleum asphalt, or bio-asphalt; and / or, the solvent includes at least one of wash oil or anthracene oil.

[0012] In some embodiments, in step (1), the mass ratio of the asphalt to the solvent is 1:1 to 5.

[0013] In some embodiments, in step (1), the mixing temperature is 90–130°C; and the mixing time is 0.5–3 h.

[0014] In some embodiments, in step (2), the mixed oil is heated to 150–400°C.

[0015] In some embodiments, in step (3), the gaseous oxidant includes at least one of ozone, oxygen or air; the mass ratio of the heated mixed oil to the gaseous oxidant is 1:0.5 to 3.

[0016] In some embodiments, in step (3), the heated mixed oil enters the oxidation tower from the middle of the oxidation tower for flash evaporation, and the gaseous oxidant is introduced from the bottom of the oxidation tower for reaction.

[0017] In some embodiments, in step (3), the pressure inside the oxidation tower is lower than the pressure of the heated mixed oil, and the pressure difference between the oxidation tower and the heated mixed oil is 1500 to 500000 Pa.

[0018] In some embodiments, in step (3), the solvent and unreacted gaseous oxidant in the light phase escaping from the top of the column are regenerated and reused.

[0019] In some embodiments, in step (4), the mass ratio of the asphalt to the desulfurization liquid is 1:0.5 to 3; the desulfurization liquid includes at least one of water, a soda ash solution with a mass fraction of 1 to 10%, and ammonia water with a mass fraction of 1 to 5%; the stirring time is 1 to 5 hours. Attached Figure Description

[0020] Figure 1 This is a flow chart of the asphalt desulfurization process of the present invention.

[0021] Figure 2 This invention relates to the oxidation reaction of sulfur-containing molecules in asphalt.

[0022] Figure label:

[0023] 1. Mixing vessel; 2. Oxidation tower; 3. Regeneration tower; 4. Solvent intermediate tank; 5. Gas-liquid separator; 6. Washing tank. Detailed Implementation

[0024] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0025] like Figure 1 As shown, an embodiment of the present invention provides a method for asphalt desulfurization, comprising the following steps:

[0026] (1) Mix asphalt with solvent to obtain mixed oil; optionally, the mixing is carried out in mixing tank 1;

[0027] (2) Heating the mixed oil; optionally, heating is performed using a tubular furnace;

[0028] (3) The heated mixed oil enters oxidation tower 2 for flash evaporation, and gaseous oxidant is introduced to react; after the reaction, the solvent and unreacted gaseous oxidant enter the light phase and escape from the top of the tower; the asphalt enters the heavy phase and is discharged from the bottom of the tower.

[0029] (4) The discharged asphalt enters the washing tank 6, and desulfurization liquid is introduced, mixed and stirred; the sulfur-rich desulfurization liquid is discharged from the top of the washing tank 6, and the desulfurized asphalt is discharged from the bottom of the washing tank 6.

[0030] The asphalt desulfurization method of this invention involves mixing asphalt with a solvent to form a mixed oil. After heating, the mixed oil is atomized through flash evaporation. The mixed oil forms small droplets or liquid films in the oxidation tower, allowing for thorough contact with the gaseous oxidant and accelerating the gas-liquid reaction. This process transforms water-insoluble structures such as thiophene sulfur in the asphalt into soluble sulfoxide or sulfone structures. Figure 2 As shown, sulfur is removed through desulfurization liquid washing and oil-water separation, effectively reducing the sulfur content in asphalt and thus obtaining high-quality asphalt suitable for producing carbon products such as needle coke and carbon fiber. In this embodiment of the invention, asphalt and solvent are mixed and then subjected to a gas-liquid reaction, avoiding the pretreatment process of asphalt pulverization, reducing the difficulty of raw material processing, energy consumption, and production costs. Compared with catalytic hydrogenation methods, the oxidation method of this invention requires milder, more efficient, and more environmentally friendly conditions. Unreacted gaseous oxidant and solvent can be recycled and reused, making it simple and easy to operate, suitable for large-scale continuous production, and with broad application prospects in fields such as coal chemical industry.

[0031] In some embodiments, in step (1), the asphalt includes at least one of coal tar pitch, petroleum asphalt, or bio-asphalt. In this embodiment of the invention, the asphalt desulfurization method can be used to desulfurize coal tar pitch, petroleum asphalt, or bio-asphalt, thereby improving their quality.

[0032] In some embodiments, in step (1), the solvent includes at least one of wash oil or anthracene oil, preferably, the anthracene oil includes at least one of mono-anthracene oil and di-anthracene oil; the solvent is preferably wash oil. In this embodiment of the invention, a mixed oil is prepared by mixing asphalt with solvents such as wash oil to reduce the viscosity of the asphalt. The mixed oil is then atomized by flash evaporation to carry out a gas-liquid reaction, effectively avoiding the pretreatment process of asphalt pulverization. After the reaction, the solvent enters the light phase, escapes from the top of the tower, and can be reused through regeneration.

[0033] In some embodiments, in step (1), the mass ratio of the asphalt to the solvent is 1:1 to 5, specifically, for example, 1:1, 1:2, 1:3, 1:4, 1:5, preferably 1:2 to 4. In these embodiments, excessive solvent usage reduces the efficiency of the oxidation tower and increases the energy consumption for desulfurization per unit of asphalt; insufficient solvent usage results in excessively high viscosity of the mixed oil, leading to excessively large droplets after flash evaporation and a low specific surface area, which is detrimental to the desulfurization reaction. By optimizing the mass ratio of asphalt to solvent, the sulfur removal rate from the asphalt can be further improved.

[0034] In some embodiments, in step (1), the mixing temperature is 90–130°C, specifically, for example, 90°C, 100°C, 110°C, 120°C, 130°C, preferably 100–120°C; the mixing time is 0.5–3 hours, specifically, for example, 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours. In this embodiment of the invention, by optimizing the mixing temperature and time, it is beneficial to ensure the thorough mixing and dispersion of asphalt and solvent, forming a mixed oil, which is beneficial to the subsequent atomization and gas-liquid reaction steps, and promotes the oxidation and removal of sulfur.

[0035] In some embodiments, in step (2), the mixed oil is heated to 150–400°C, specifically, for example, 150°C, 200°C, 250°C, 300°C, 350°C, 400°C, preferably 150–250°C. In this embodiment of the invention, by controlling the feed temperature of the mixed oil in the oxidation tower, gaseous oxidants such as ozone can selectively react with thiophene sulfur, mercaptans, or sulfides in the asphalt, which is beneficial for reducing the sulfur content in the asphalt and can yield high-quality asphalt suitable for producing carbon products such as needle coke and carbon fiber. When the heating temperature is too high, the asphalt is prone to coking in the oxidation tower, leading to material blockage; when the heating temperature is too low, the reaction between the asphalt and the gaseous oxidant is insufficient, reducing the desulfurization efficiency.

[0036] In some embodiments, in step (3), the gaseous oxidant includes at least one of ozone, oxygen, or air, preferably ozone; the mass ratio of the heated mixed oil to the gaseous oxidant is 1:0.5 to 1:3, specifically, for example, 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3. In this embodiment of the invention, gaseous oxidants such as ozone are used to oxidize sulfur in asphalt. The mixed oil forms small droplets or liquid films in the packed tower, which come into full contact with the gaseous oxidant, accelerating the gas-liquid reaction with the gaseous oxidant. The gaseous oxidant ozone leaves no residue after reaction, causes no pollution, and can be purified and reused.

[0037] In some embodiments, in step (3), the heated mixed oil enters the oxidation tower 2 from the middle for flash evaporation, and the gaseous oxidant is introduced from the bottom of the oxidation tower 2 for reaction. In this embodiment of the invention, the heated mixed oil enters the oxidation tower from the middle for flash evaporation, and the gaseous oxidant is introduced from the bottom of the oxidation tower. The mixed oil and the gaseous oxidant flow counterclockwise, and are thoroughly stirred and mixed, which is beneficial for further contact between the mixed oil and the gaseous oxidant, fully oxidizing the sulfur in the asphalt and improving the sulfur removal rate. The oxidation tower can also further adjust the carbon-hydrogen ratio of the asphalt, which is beneficial for further processing of the asphalt.

[0038] In some embodiments, in step (3), the pressure inside the oxidation tower is lower than the pressure of the heated mixed oil, and the pressure difference between the oxidation tower and the heated mixed oil is 1500–500000 Pa, specifically, for example, 1500 Pa, 5000 Pa, 10000 Pa, 50000 Pa, 100000 Pa, 200000 Pa, 300000 Pa, 400000 Pa, and 500000 Pa. In this embodiment of the invention, the pressure of the oxidation tower is lower than the pressure of the heated mixed oil. By optimizing the pressure difference between the oxidation tower and the mixed oil, it is beneficial for the mixed oil to undergo flash evaporation and subsequent oxidation reaction. If the pressure difference is too high, the pressure inside the oxidation tower will be too high, which is not conducive to solvent removal and smooth operation of the device; if the pressure difference is too low, the atomization effect will be poor, which is not conducive to the oxidation reaction.

[0039] In some embodiments, in step (3), the solvent and unreacted gaseous oxidant in the light phase escaping from the top of the column are regenerated and reused. Preferably, the light phase escaping from the top of the column enters the gas-liquid separator 5, is cooled, and separated into gas and liquid. The gas enters the regeneration tower 3 for regeneration to obtain gaseous oxidant, and the liquid enters the solvent intermediate tank 4 for purification and impurity removal to obtain solvent, which is then reused. In this embodiment of the invention, the solvent and gaseous oxidant are purified and regenerated for reuse, which is environmentally friendly and reduces production costs.

[0040] In some embodiments, in step (4), the mass ratio of asphalt to desulfurization liquid is 1:0.5 to 3, specifically, for example, 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, preferably 1:0.5 to 2; the desulfurization liquid includes at least one of water, a 1-10% soda ash solution, and a 1-5% ammonia solution; the stirring time is 1-5 hours, specifically, for example, 1 hour, 2 hours, 3 hours, 4 hours, and 5 hours. In this embodiment of the invention, the insoluble thiophene sulfur and other structures in asphalt are converted into soluble sulfoxide or sulfone structures through gas-liquid reaction, and then sulfur is removed by washing with desulfurization liquid and oil-water separation to obtain sulfur-rich water and desulfurized asphalt, effectively reducing the sulfur content in asphalt. By optimizing the mass ratio of asphalt to desulfurization liquid and the stirring time, it is beneficial to further improve the sulfur removal rate and improve the quality of asphalt.

[0041] The present invention will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way.

[0042] Example 1

[0043] Coal tar desulfurization methods:

[0044] Table 1 Analytical Indicators of Raw Coal Tar Pitch

[0045] Coal tar pitch 76 7.4 0.71 46.8 1.10

[0046] Includes the following steps:

[0047] (1) Coal tar pitch and wash oil are injected into mixing tank 1 at a mass ratio of 1:1. The temperature inside the tank is 110℃. The mixture is thoroughly mixed for 2 hours to obtain mixed oil. The indicators of coal tar pitch are shown in Table 1.

[0048] (2) Heat the mixed oil to 190°C using a tubular furnace;

[0049] (3) The heated mixed oil enters oxidation tower 2 from the middle for flash evaporation, while ozone gas is introduced from the bottom of oxidation tower 2 for reaction. The pressure difference between oxidation tower 2 and the mixed oil is 100,000 Pa, and the mass ratio of the heated mixed oil to ozone is 1:2. After the reaction, the wash oil and unreacted ozone enter the light phase and escape from the top of the tower. The ozone and wash oil are then cooled, separated by gas-liquid separation, purified, and regenerated before being reused. The coal tar pitch enters the heavy phase and is discharged from the bottom of the tower.

[0050] (4) The discharged coal tar pitch enters the washing tank 6 and is mixed with water at a mass ratio of 1:2 for 3 hours. The water phase is discharged from the top to obtain sulfur-rich water, and the desulfurized pitch is discharged from the bottom.

[0051] Tests showed that the sulfur content of the desulfurized asphalt was 0.362%.

[0052] Example 2

[0053] Coal tar desulfurization methods:

[0054] Includes the following steps:

[0055] (1) Coal tar pitch and wash oil are injected into mixing kettle 1 at a mass ratio of 1:2. The temperature inside the kettle is 100℃. The mixture is thoroughly mixed for 3 hours to obtain mixed oil. The indicators of coal tar pitch are shown in Table 1.

[0056] (2) Heat the mixed oil to 150°C using a tubular furnace;

[0057] (3) The heated mixed oil enters oxidation tower 2 from the middle for flash evaporation, while ozone gas is introduced from the bottom of oxidation tower 2 for reaction. The pressure difference between oxidation tower 2 and the mixed oil is 10000 Pa, and the mass ratio of the heated mixed oil to ozone is 1:3. After the reaction, the wash oil and unreacted ozone enter the light phase and escape from the top of the tower. The ozone and wash oil are then cooled, separated by gas-liquid separation, purified, and regenerated before being reused. The coal tar pitch enters the heavy phase and is discharged from the bottom of the tower.

[0058] (4) The discharged coal tar pitch enters the washing tank 6 and is mixed with water at a mass ratio of 1:1 for 5 hours. The water phase is discharged from the top to obtain sulfur-rich water, and the desulfurized pitch is discharged from the bottom.

[0059] Tests showed that the sulfur content of the desulfurized asphalt was 0.275%.

[0060] Example 3

[0061] Coal tar desulfurization methods:

[0062] Includes the following steps:

[0063] (1) Coal tar pitch and wash oil are injected into mixing tank 1 at a mass ratio of 1:5. The temperature inside the tank is 120℃. Mix thoroughly for 1 hour to obtain mixed oil. The indicators of coal tar pitch are shown in Table 1.

[0064] (2) Heat the mixed oil to 350°C using a tubular furnace;

[0065] (3) The heated mixed oil enters oxidation tower 2 from the middle for flash evaporation, while ozone gas is introduced from the bottom of oxidation tower 2 for reaction. The pressure difference between oxidation tower 2 and the mixed oil is 500,000 Pa, and the mass ratio of the heated mixed oil to ozone is 1:0.5. After the reaction, the wash oil and unreacted ozone enter the light phase and escape from the top of the tower. The ozone and wash oil are then cooled, separated by gas-liquid separation, purified, and regenerated before being reused. The coal tar pitch enters the heavy phase and is discharged from the bottom of the tower.

[0066] (4) The discharged coal tar pitch enters the washing tank 6 and is mixed with ammonia water with a mass fraction of 3% at a mass ratio of 1:3. The mixing time is 1 hour. The aqueous phase is discharged from the top to obtain sulfur-rich water, and the desulfurized pitch is discharged from the bottom.

[0067] Tests showed that the sulfur content of the desulfurized asphalt was 0.375%.

[0068] Example 4

[0069] The method is exactly the same as in Example 1, except that the solvent in step (1) is anthracene oil.

[0070] Tests showed that the sulfur content of the desulfurized asphalt was 0.785%.

[0071] Example 5

[0072] The method is exactly the same as in Example 1, except that in step (2), the temperature is raised to 500°C.

[0073] Tests showed that the sulfur content of the desulfurized asphalt was 0.305%, but severe coking occurred inside the oxidation tower.

[0074] Example 6

[0075] The method is exactly the same as in Example 1, except that in step (2), the temperature is raised to 120°C.

[0076] Tests showed that the sulfur content of the desulfurized asphalt was 0.84%.

[0077] Example 7

[0078] The method is exactly the same as in Example 1, except that the mass ratio of the heated mixed oil to ozone in step (3) is 1:0.2.

[0079] Tests showed that the sulfur content of the desulfurized asphalt was 0.85%.

[0080] Comparative Example 1

[0081] The method is exactly the same as in Example 1, except that ozone is not introduced in step (3).

[0082] Tests showed that the sulfur content of the desulfurized asphalt was 0.92%.

[0083] Comparative Example 2

[0084] The method is exactly the same as in Example 1, except that step (3) involves introducing ozone into the heated mixed oil, wherein the mass ratio of the heated mixed oil to ozone is 1:2. The reacted mixture enters the oxidation tower 2 from the middle for flash evaporation, and the pressure difference between the oxidation tower 2 and the mixture is 100,000 Pa. The wash oil and unreacted ozone enter the light phase and escape from the top of the tower, while the coal tar pitch enters the heavy phase and is discharged from the bottom of the tower.

[0085] Tests showed that the sulfur content of the desulfurized asphalt was 0.88%.

[0086] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0087] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.

Claims

1. A method for desulfurizing asphalt, characterized in that, Includes the following steps: (1) Mixing asphalt with a solvent to obtain a mixed oil; the solvent includes wash oil; (2) Heating the mixed oil; the mixed oil is heated to 150~400℃; (3) The heated mixed oil enters the oxidation tower for flash evaporation. After flash evaporation, the mixed oil is atomized and a gaseous oxidant is introduced to react. After the reaction, the solvent and unreacted gaseous oxidant enter the light phase and escape from the top of the tower. The asphalt enters the heavy phase and is discharged from the bottom of the tower. The mass ratio of the heated mixed oil to the gaseous oxidant is 1:0.5~3. The heated mixed oil enters the oxidation tower from the middle for flash evaporation, and the gaseous oxidant is introduced from the bottom of the oxidation tower to react. (4) The discharged asphalt enters the washing tank, and desulfurization liquid is introduced, mixed and stirred; the sulfur-rich desulfurization liquid is discharged from the top of the washing tank, and the desulfurized asphalt is discharged from the bottom of the washing tank.

2. The asphalt desulfurization method according to claim 1, characterized in that, In step (1), the asphalt includes at least one of coal tar pitch, petroleum asphalt, or bio-asphalt.

3. The asphalt desulfurization method according to claim 1, characterized in that, In step (1), the mass ratio of the asphalt to the solvent is 1:1~5.

4. The asphalt desulfurization method according to claim 1, characterized in that, In step (1), the mixing temperature is 90~130℃; the mixing time is 0.5~3h.

5. The asphalt desulfurization method according to claim 1, characterized in that, In step (3), the gaseous oxidant includes at least one of ozone, oxygen, or air.

6. The asphalt desulfurization method according to claim 1, characterized in that, In step (3), the pressure inside the oxidation tower is lower than the pressure of the heated mixed oil, and the pressure difference between the oxidation tower and the heated mixed oil is 1500~500000Pa.

7. The asphalt desulfurization method according to claim 1, characterized in that, In step (3), the solvent and unreacted gaseous oxidant in the light phase escaping from the top of the column are regenerated and reused.

8. The asphalt desulfurization method according to claim 1, characterized in that, In step (4), the mass ratio of the asphalt to the desulfurization liquid is 1:0.5~3; the desulfurization liquid includes at least one of water, a soda ash solution with a mass fraction of 1~10%, and ammonia water with a mass fraction of 1~5%; the stirring time is 1~5 h.

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