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CN-119432434-B - Processing method of high-sulfur high-nitrogen low-grade diesel oil

CN119432434BCN 119432434 BCN119432434 BCN 119432434BCN-119432434-B

Abstract

The invention discloses a processing method of high-sulfur high-nitrogen low-grade diesel, which comprises the following steps of (1) mixing low-grade diesel raw materials with alkali metal in the presence of hydrogen, then entering an alkali metal treatment reaction zone, (2) entering a separation unit from a reaction effluent obtained in the step (1) to obtain a liquid-phase material flow, (3) mixing the liquid-phase material flow in the step (2) with an oxidant, entering an oxidation reaction zone for reaction, and (4) entering an extraction unit from the reaction effluent obtained in the step (3) to obtain a final clean diesel product under the action of the extractant. The method adopts a non-hydrogenation technical means to process the inferior diesel oil, and can directly produce clean diesel oil with low sulfur, low nitrogen and high cetane number.

Inventors

  • Man Chenbing
  • YANG YANG
  • YU YING
  • LIU LING
  • MENG ZHAOHUI

Assignees

  • 中国石油化工股份有限公司
  • 中石化（大连）石油化工研究院有限公司

Dates

Publication Date
20260505
Application Date
20230728

Claims (20)

  1. 1. A processing method of high-sulfur high-nitrogen low-grade diesel oil is characterized by comprising the following steps: (1) Mixing a poor diesel raw material with alkali metal in the presence of hydrogen, and then entering an alkali metal treatment reaction zone; (2) The reaction effluent obtained in the step (1) enters a separation unit to obtain a liquid-phase material flow; (3) Mixing the liquid-phase material flow in the step (2) with an oxidant and entering an oxidation reaction zone for reaction; (4) The reaction effluent obtained in the step (3) enters an extraction unit, and a final clean diesel oil product is obtained under the action of an extractant; The operating conditions of the alkali metal treatment reaction zone in the step (1) are that the reaction temperature is 280-340 ℃ and the residence time is 5-40min; The reaction effluent obtained in the step (3) enters an extraction unit, and a final clean diesel oil product is obtained under the action of an extractant, which comprises the following specific contents: S1, dividing the reaction effluent obtained in the step (3) into a first material and a second material; S2, the first material obtained in the step S1 enters an extraction unit, and a final clean diesel oil product is obtained under the action of an extractant; S3, recycling the second material obtained in the step S1 to the alkali metal treatment reaction zone; in the step S1, the mass ratio of the first material to the second material is 1 (0.1-0.3); The sulfur content of the poor diesel fuel raw material in the step (1) is higher than 6000 mug/g, and the nitrogen content is higher than 800 mug/g; the alkali metal in the step (1) comprises one or more of lithium, sodium, potassium, rubidium and cesium; The molar ratio of the alkali metal to the sulfur content of the poor diesel raw material in the step (1) is 1.5-3.5; Mixing the alkali metal with a dispersion medium in the step (1) to obtain an alkali metal dispersion, and mixing the alkali metal dispersion with a poor diesel raw material and then entering an alkali metal treatment reaction zone; The dispersion medium in the step (1) comprises one or more of n-pentadecane, n-hexadecane, benzene, toluene and xylene, and the mass ratio of the alkali metal to the dispersion medium is 1 (1-3).
  2. 2. The method according to claim 1, wherein the sulfur content of the poor diesel fuel raw material in the step (1) is 8000-15000 mug/g and the nitrogen content is 1000-2500 mug/g.
  3. 3. The method of claim 1, wherein the alkali metal in step (1) comprises one or more of lithium, sodium and potassium.
  4. 4. The method according to claim 1, wherein the alkali metal in step (1) is sodium.
  5. 5. The method of claim 1, wherein the molar ratio of alkali metal to sulfur in the poor diesel fuel in the step (1) is 2.0-3.0.
  6. 6. The method according to claim 1, wherein the alkali metal is mixed with the dispersion medium in the step (1) by one or more of a high-speed stirring method, a pump jet method, a colloid mill method and an ultrasonic method.
  7. 7. The method according to claim 6, wherein the alkali metal and the dispersion medium are mixed in the step (1) by a high-speed stirring method.
  8. 8. The method of claim 6, wherein the alkali metal and the dispersion medium are mixed in the step (1) under the conditions of proper temperature, time and stirring rate by adopting a high-speed stirring method, wherein the temperature is 70-150 ℃, the time is 10-60min, and the stirring rate is 2000-10000r/min.
  9. 9. The method of claim 8, wherein the alkali metal is mixed with the dispersion medium in the step (1) under the conditions of a suitable temperature, time and stirring rate by a high-speed stirring method, wherein the temperature is 100-130 ℃, the time is 20-40min, and the stirring rate is 4000-8000r/min.
  10. 10. The process according to claim 1, wherein the alkali metal particles in the alkali metal dispersion in step (1) have a diameter distribution in the range of 5 to 100. Mu.m.
  11. 11. The method according to claim 10, wherein the alkali metal particles in the alkali metal dispersion in step (1) have a diameter distribution in the range of 10 to 30. Mu.m.
  12. 12. The method according to claim 1, wherein 1 to 3 alkali metal treatment reactors are arranged in the alkali metal treatment reaction zone in the step (1), and the alkali metal treatment reactors are any one of a kettle type reactor, a tubular type reactor and a jet reactor.
  13. 13. The method according to claim 12, wherein 1 alkali metal treatment reactor is arranged in the alkali metal treatment reaction zone in the step (1), and the alkali metal treatment reactor is a kettle reactor.
  14. 14. The method according to claim 12, wherein the alkali metal treatment reactor in the step (1) is a stirred tank reactor.
  15. 15. The process according to claim 1, wherein the operating conditions of the alkali metal treatment reaction zone in the step (1) are a reaction pressure of 2.0 to 20.0MPa and a hydrogen-oil volume ratio of 100 to 2000Nm 3 /m 3 .
  16. 16. The process according to claim 15, wherein the operating conditions of the alkali metal treatment reaction zone in the step (1) are a reaction pressure of 5.0 to 15.0MPa, a residence time of 10 to 25min and a hydrogen-oil volume ratio of 500 to 1500Nm 3 /m 3 .
  17. 17. The method according to claim 1, wherein the separation unit in the step (2) is solid-liquid separation by at least one of decantation, filtration, centrifugal separation and gravity sedimentation.
  18. 18. The method of claim 17, wherein the separation unit in the step (2) is solid-liquid separation, and a centrifugal separation method is adopted.
  19. 19. The method of claim 1, wherein the oxidizing agent in step (3) comprises at least one of an organic peroxyacid, an inorganic peroxyacid, and a peroxysalt.
  20. 20. The method according to claim 19, wherein the oxidizing agent in the step (3) is hydrogen peroxide-organic acid with a concentration of 30wt%, the organic acid comprises at least one of formic acid, acetic acid and propionic acid, and the volume ratio of the organic acid to the hydrogen peroxide with a concentration of 30wt% is (0.5-4.0): 1.

Description

Processing method of high-sulfur high-nitrogen low-grade diesel oil Technical Field The invention belongs to the technical field of petrochemical industry, relates to a processing method of high-sulfur high-nitrogen low-grade diesel, and in particular relates to a method for producing clean diesel by processing high-sulfur high-nitrogen low-grade diesel. Background The main secondary processing diesel oil in China is catalytic cracking diesel oil and delayed coking diesel oil. With the continuous intensification of the crude oil heaviness and the poor quality and the continuous deepening of the heavy oil conversion degree in the world, the property of the secondary processing diesel oil in China is further deteriorated, and the secondary processing diesel oil is mainly characterized in that the content of impurities such as sulfur content, nitrogen content and the like is further increased, and the cetane number is further reduced. On the other hand, with the continuous improvement of environmental protection requirements, the requirements of various countries in the world on vehicle fuels are also higher and higher. From day 1 of 7 of 2023, the six emission standard 6b stage of China is fully implemented, the diesel oil index is strictly controlled, the sulfur content is required to be reduced to below 0.035wt%, the lubricating property of the automobile and the methyl ester are required to be fuel index, the polycyclic aromatic hydrocarbon index is reduced to 7wt%, and the cetane number is further improved to 49. The low quality characteristics of high sulfur and high nitrogen low grade diesel oil are in great contradiction with the increasingly improved diesel oil product index. It can be seen how to produce clean diesel from high-sulfur high-nitrogen poor diesel is a significant problem for oil refining enterprises. Aiming at the situation, the prior art generally adopts hydrogenation technology to treat high-sulfur high-nitrogen poor diesel oil and produce clean diesel oil meeting the environmental protection requirement. CN106554815A discloses a process for producing clean diesel, which comprises mixing the reaction products of the high sulfur nitrogen poor diesel and the second hydrogenation reaction zone with hydrogen-containing stream, then reacting in the first hydrogenation reaction zone to obtain hydrofining reaction product, separating and fractionating to obtain refined diesel fraction and heavy diesel fraction, introducing at least part of the heavy diesel fraction and hydrogen-containing stream into the second hydrogenation reaction zone, introducing the product of the second hydrogenation reaction zone into the first hydrogenation reaction zone, and mixing the refined diesel fraction with the rest of the heavy diesel fraction to obtain clean diesel, wherein sulfur content in the high sulfur nitrogen poor diesel is higher than 5000 μg/g, nitrogen content is higher than 700 μg/g, aromatic content is higher than 50 wt%. CN111286360a discloses a diesel hydrofining device and method, the diesel raw material is divided into light and heavy fractions by prefractionator, so that the light fraction contains almost no dibenzothiophene and its derivative, and the heavy fraction contains almost all dibenzothiophene and its derivative which are difficult to hydrodesulfurize, the sulfides in the light fraction are mainly thiol, disulfide, thiophenes and benzothiophenes sulfides, and can be removed under lower reaction severity, and the heavy fraction contains mainly sulfide and polycyclic aromatic hydrocarbon which are difficult to remove dibenzothiophenes sulfides, so that the sulfur content of heavy diesel product is reduced to below 10ppm, and the content of polycyclic aromatic hydrocarbon is strictly controlled, and the severity of reaction is slightly higher than that of general diesel hydrogenation reactor. However, the hydrogenation technology in the patent has strict requirements on reaction conditions, is difficult to deeply remove nitrogen-containing compounds and sulfur-containing compounds in diesel oil, has high production cost, and limits the further application of the technology in the field of poor-quality diesel oil processing. Disclosure of Invention Aiming at the defects of the prior art, the invention provides a processing method of high-sulfur high-nitrogen low-grade diesel oil. The method adopts a non-hydrogenation technical means to process the inferior diesel oil, and can directly produce clean diesel oil with low sulfur, low nitrogen and high cetane number. The processing method of the high-sulfur high-nitrogen low-grade diesel oil comprises the following steps: (1) Mixing a poor diesel raw material with alkali metal in the presence of hydrogen, and then entering an alkali metal treatment reaction zone; (2) The reaction effluent obtained in the step (1) enters a separation unit to obtain a liquid-phase material flow; (3) Mixing the liquid-phase material flow in the step (2) with