A process for diesel hydrodesulfurization reaction
By employing a low-temperature zone for aromatic saturation and a high-temperature zone for desulfurization in the diesel hydrotreating process, and using a specific catalyst combination, the problems of high energy consumption and short catalyst life in the diesel hydrotreating process have been solved, achieving low-energy and high-efficiency desulfurization that meets the China VIB standard.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2024-12-04
- Publication Date
- 2026-06-05
AI Technical Summary
Existing diesel hydrotreating processes require increased reaction temperatures to remove difficult-to-remove substituted dibenzothiophene compounds, leading to increased energy consumption and shortened catalyst life. Furthermore, existing solutions fail to effectively combine the optimization of hydrotreating and desulfurization reactions.
The process employs a combination of catalysts with different activities, involving low-temperature hydrogenation saturation of aromatics and high-temperature desulfurization. First, aromatics are saturated in the low-temperature zone using a hydrogenation refining catalyst, and then desulfurization is carried out in the high-temperature zone using a catalyst with stronger desulfurization capabilities, thereby reducing the overall reaction temperature.
It achieves efficient removal of sulfides from diesel fuel at lower temperatures, reducing energy consumption and extending catalyst life, while meeting the diesel sulfur content requirements of the China VIB standard.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of diesel hydrodesulfurization technology, and specifically to a low-energy-consumption diesel hydrodesulfurization process. Background Technology
[0002] The China VIB standard for automotive diesel fuel requires a sulfur content of less than 10 ppm. The primary goal of diesel hydrotreating is to remove sulfur-containing substances. Diesel fuel contains various sulfur-containing substances, each with varying degrees of difficulty in removal. Among these, the most difficult to remove are substituent-containing dibenzothiophenes, such as 4,6-DMDBT. Currently, the main industrial method for removing these most difficult substances is to achieve ultra-deep desulfurization by increasing the reaction temperature. However, higher reaction temperatures lead to increased energy consumption in the production process.
[0003] CN113462431A discloses a method for producing diesel and jet fuel, in which raw materials are passed through a first reaction zone and a second reaction zone to obtain the products. The reaction temperature in the second reaction zone is 10-80°C lower than that in the first reaction zone. This patented method achieves hydrogenation of the oil at different temperature zones, but it does not adequately consider the impurities in the diesel feedstock, nor does it provide any feasible solutions regarding the principles and sequence of the hydrogenation and desulfurization reactions.
[0004] EP4133030A1 proposes a method for producing olefins and aromatic compounds, in which the feedstock undergoes a first hydrogenation treatment step at temperatures below 200°C, followed by a second hydrogenation treatment step at temperatures above 200°C. The low-temperature stage of this method is primarily used to remove unsaturated olefinic substances from the feedstock, and the low temperature is not suitable for the aromatic ring saturation of 4,6-DMDBT-like substances. Summary of the Invention
[0005] Based on the analysis and consideration of the properties of major sulfur impurities in feedstock oil, the inventors believe that the reason why substituent-containing dibenzothiophenes are difficult to remove is that, taking 4,6-DMDBT as an example, the two methyl groups at positions 4 and 6 block the contact between sulfur atoms in the molecule and the active sites on the catalyst surface, increasing the difficulty of desulfurization. Therefore, one approach to desulfurizing 4,6-DMDBT is to first hydrogenate one or both benzene rings in the molecule. The resulting cyclohexane ring is easily deformed, exposing the sulfur atoms that were originally blocked by the methyl groups in the same plane to a greater extent. The sulfur atoms can then easily contact the active sites on the catalyst surface, thus allowing the desulfurization reaction to occur at a lower reaction temperature and reducing the sulfur content of diesel fuel. Directly removing the sulfur atoms from the 4,6-DMDBT molecule without hydrogenation is also a feasible approach. However, in this case, the reaction temperature needs to be significantly increased to remove the sulfur atoms blocked by the methyl groups, which will increase the energy consumption of the diesel production process, and the high temperature may also shorten the catalyst life.
[0006] The reaction temperature of diesel hydrogenation is determined by the temperature required for desulfurization. Compared to the commonly used industrial diesel hydrogenation reaction temperatures, the temperature required to achieve hydrogen saturation of the benzene ring in the 4,6-DMDBT molecule is lower. Benzene ring hydrogenation is an exothermic reaction; further increasing the reaction temperature would hinder the hydrogenation saturation reaction. Therefore, the inventors believe that conducting the hydrogenation reaction before the desulfurization reaction is a more reasonable approach.
[0007] Based on this, in order to address the problem of the difficulty in removing substituent-containing dibenzothiophene sulfur compounds, this invention proposes a low-energy diesel hydrodesulfurization process. A hydrorefining catalyst with stronger hydrorefining capacity is first used to moderately saturate the aromatics in the diesel in a low-temperature zone. The resulting intermediate product enters a high-temperature zone and is desulfurized using a hydrorefining catalyst with stronger desulfurization capacity.
[0008] To achieve the above technical objectives, the technical solution of the present invention is as follows:
[0009] A process for hydrodesulfurization of diesel fuel involves first passing the diesel feedstock through a low-temperature zone for a hydrogenation-based aromatic saturation reaction, followed by a high-temperature zone for a desulfurization-based reaction. The low-temperature zone has a reaction temperature of 210-320°C, a desulfurization rate of less than 50%, and a dibenzothiophene sulfide saturation rate of greater than 50%. The high-temperature zone has a reaction temperature of 320-450°C, resulting in a total desulfurization rate of not less than 99.9% for the feedstock after passing through the high-temperature zone.
[0010] In the above process methods, those skilled in the art should understand that desulfurization reactions also occur in the low-temperature zone, but their main purpose is to saturate one or two aromatic rings of the difficult-to-desulfurize substances. A small amount of dearomatization reactions also occur in the high-temperature zone, but their main function is to remove sulfur atoms from the oil. Using a method of hydrogenation followed by desulfurization can significantly reduce the reaction temperature required for desulfurization, thereby reducing energy consumption.
[0011] Furthermore, the reaction temperature in the low-temperature zone is preferably 210-300℃, more preferably 220-280℃.
[0012] Furthermore, the main purpose of the low-temperature region is to hydrogenate and saturate the aromatic rings in the dibenzothiophene sulfide molecules. Based on the aromatic ring saturation rate of the dibenzothiophene compound, the aromatic ring saturation rate in the low-temperature region is higher than 50%, preferably higher than 70%, and more preferably higher than 85%.
[0013] Furthermore, those skilled in the art will understand that direct desulfurization of diesel fuel without undergoing hydrosaturation in a low-temperature zone requires a higher reaction temperature. In this invention, the reaction temperature in the low-temperature zone is much lower than the reaction temperature required to desulfurize diesel feedstock to 10 ppm. Based on the total desulfurization rate of the feedstock, the reaction temperature in the low-temperature zone ensures that the desulfurization rate of the feedstock is less than 50%, preferably less than 75%.
[0014] Furthermore, to lower the reaction temperature in the low-temperature zone and obtain higher aromatic ring hydrogenation saturation activity, catalyst I is used in the low-temperature zone. Catalyst I is a catalyst with high aromatic ring saturation activity. Under the same conditions, the aromatic ring saturation activity of catalyst I is more than 10% higher than that of catalyst II used in the high-temperature zone, preferably more than 20% higher, more preferably more than 30% higher, and most preferably more than 40% higher. The aromatic ring saturation activity is defined as the saturation rate of dibenzothiophene compounds in the feedstock before and after the reaction. For example, a 10% increase in aromatic ring saturation activity means that the aromatic saturation rate of dibenzothiophene compounds in the feedstock is 10% higher after the reaction.
[0015] Furthermore, the main purpose of the high-temperature zone is to remove sulfur atoms from the saturated dibenzothiophene sulfide molecules. To meet the clean diesel quality standards, the reaction temperature of the high-temperature zone needs to be adjusted based on the results of the low-temperature zone to optimize the overall desulfurization effect, aiming for a total desulfurization rate of not less than 99.9% across both reaction zones, producing diesel products with a sulfur content of less than 10 ppm. In the technical solution of this invention, the diesel desulfurization temperature is significantly reduced after pre-saturation in the low-temperature zone. Therefore, the reaction temperature of the high-temperature zone is preferably 325-420℃, and more preferably 330-380℃.
[0016] Those skilled in the art will understand that the pre-saturation of the low-temperature zone in this invention reduces the difficulty of desulfurization of sulfur atoms in dibenzothiophene sulfide molecules in the high-temperature zone and reduces the influence of substituents. Therefore, as a further preferred embodiment, catalyst II required in the high-temperature zone has high desulfurization activity. Under the same conditions, the desulfurization activity of catalyst II is more than 20% higher than that of catalyst I, preferably more than 28% higher, and more preferably more than 35% higher. The desulfurization activity is based on the desulfurization rate of the raw materials before and after the reaction. For example, a 20% higher desulfurization activity means a 20% higher desulfurization rate of the raw materials after the reaction.
[0017] In the technical solution of this invention, catalyst I used in the low-temperature zone reaction and catalyst II used in the high-temperature zone respectively possess high aromatic ring saturation activity and high desulfurization activity. Those skilled in the art, based on the overall inventive concept and the aforementioned performance requirements, can select catalysts from the prior art that meet the requirements of this invention to achieve the technical effects of this invention. As one more specific embodiment, this invention still provides a better catalyst combination than the prior art. Using the catalyst combination of this invention can effectively reduce the temperature of the two reaction zones, making the overall temperature lower than the level of the prior art, and reducing reaction energy consumption. In the catalyst combination of this invention, catalyst I and catalyst II use alumina or modified alumina as supports, and nickel oxide and molybdenum oxide as active components. Catalyst I and catalyst II have different NiO / MoO3 weight ratios. The NiO / MoO3 weight ratio in catalyst I is 1.05-20.0 times that in catalyst II, preferably 1.1-15.0 times.
[0018] Furthermore, based on the weight of the catalyst, the catalyst I contains 10%-35% molybdenum oxide and 4%-15% nickel oxide. The NiO / MoO3 weight ratio in catalyst I is 0.160-0.700.
[0019] Furthermore, based on the weight of the catalyst, the catalyst II contains 12%-33% molybdenum oxide and 0.9%-3.9% nickel oxide. The NiO / MoO3 weight ratio in catalyst II is 0.030-0.159.
[0020] Furthermore, the low-temperature zone and high-temperature zone described in this invention provide two operating conditions for raw material processing. The two reaction zones can be in one reactor, with two catalyst beds set up and the temperature of each reaction zone controlled in a segmented manner. Alternatively, they can be divided into two different reactors in series, with their reaction temperatures controlled separately to meet the requirements.
[0021] Compared with the prior art, the present invention has the following advantages:
[0022] This invention utilizes low-temperature and high-temperature zones to achieve the hydrogenation and desulfurization functions required for ultra-deep diesel desulfurization, respectively. Although the realization of these two functions cannot be strictly limited to their respective target zones, this invention, through the combined use of catalysts with different performance characteristics and clever temperature and performance matching, enables the low-temperature zone to focus on aromatic ring saturation as the main reaction and the high-temperature zone to focus on desulfurization as the main reaction. This reduces the maximum temperature required for desulfurization, lowers the furnace temperature, and consequently reduces the energy consumption of the entire processing procedure.
[0023] Other features and advantages of the present invention will be described in detail in the following detailed description section. Detailed Implementation
[0024] The following non-limiting embodiments are intended to enable those skilled in the art to more fully understand the invention, but do not limit the invention in any way.
[0025] In Examples 1-2, high hydrogenation performance (high aromatic ring saturation activity) catalysts A1, A2, A3, and A4 and high desulfurization performance catalysts B1, B2, B3, and B4 were prepared. The NiO and MoO3 contents in the catalysts were calculated based on the feed amount during impregnation. All contents are weight percentages.
[0026] Example 1
[0027] Preparation of high-hydrogenation-performance catalysts A1-A4:
[0028] Take 2000g of macroporous aluminum hydroxide, add nitric acid and water to obtain a mixture with HNO3 content of 2.6% and water content of 69%. Extrude the mixture on an extruder to obtain clover-shaped strips with a diameter of 1.8 mm. Dry at 120℃ for 3 hours and then calcine at 610℃ for 4 hours to obtain a carrier.
[0029] Ammonium heptamolybdate and nickel nitrate were prepared into aqueous solutions of different concentrations. These solutions were then impregnated with the aforementioned carrier in equal volumes for 40 minutes to obtain particles with different molybdenum oxide and nickel oxide contents. These particles were dried at 110°C for 4 hours and then calcined at 560°C for 3 hours to obtain catalyst series A.
[0030] The A1 catalyst has a nickel oxide content of 4%, a molybdenum oxide content of 24%, and a NiO / MoO3 weight ratio of 0.167.
[0031] The A2 catalyst has a nickel oxide content of 6%, a molybdenum oxide content of 18%, and a NiO / MoO3 weight ratio of 0.333.
[0032] The A3 catalyst has a nickel oxide content of 9%, a molybdenum oxide content of 13%, and a NiO / MoO3 weight ratio of 0.692.
[0033] The A4 catalyst has a nickel oxide content of 10%, a molybdenum oxide content of 32%, and a NiO / MoO3 weight ratio of 0.313.
[0034] Example 2
[0035] Preparation of high desulfurization performance catalysts B1-B4:
[0036] Take 2000g of macroporous aluminum hydroxide, add nitric acid and water to obtain a mixture with HNO3 content of 2.6% and water content of 69%. Extrude the mixture on an extruder to obtain clover-shaped strips with a diameter of 1.8 mm. Dry at 120℃ for 3 hours and then calcine at 610℃ for 4 hours to obtain a carrier.
[0037] Ammonium heptamolybdate and nickel nitrate were prepared into aqueous solutions of different concentrations. These solutions were then impregnated with the aforementioned carrier in equal volumes for 40 minutes to obtain particles with different molybdenum oxide and nickel oxide contents. These particles were dried at 110°C for 4 hours and then calcined at 560°C for 3 hours to obtain catalyst series A.
[0038] Catalyst B1 has a nickel oxide content of 1%, a molybdenum oxide content of 27%, and a NiO / MoO3 weight ratio of 0.037.
[0039] The B2 catalyst has a nickel oxide content of 2%, a molybdenum oxide content of 20%, and a NiO / MoO3 weight ratio of 0.100.
[0040] The B3 catalyst has a nickel oxide content of 3%, a molybdenum oxide content of 23%, and a NiO / MoO3 weight ratio of 0.130.
[0041] The B4 catalyst has a nickel oxide content of 3.5%, a molybdenum oxide content of 31%, and a NiO / MoO3 weight ratio of 0.113.
[0042] In Example 3, the activity of the two series of catalysts described above was evaluated under the same conditions:
[0043] Example 3
[0044] The activity of the A-series high dearomatization performance catalyst and the B-series high desulfurization performance catalyst was evaluated under the same reaction conditions.
[0045] The feedstock was a blended diesel oil supplied by a Sinopec refinery, with a sulfur content of 13,600 ppm, including 950 ppm of dibenzothiophene sulfides.
[0046] The hydrogenation performance of eight catalysts from two series (A and B) was evaluated using a 100 mL fixed-bed hydrogenation unit. The desulfurization rate and aromatic saturation rate were calculated based on the changes in sulfur content and benzothiophene sulfide content in diesel fuel before and after the reaction.
[0047] Pre-sulfurization conditions for the catalyst: using jet fuel containing 3 wt% CS2, at a space velocity of 1.5 h⁻¹ -1 The catalyst was pre-sulfurized at an operating pressure of 4.0 MPa with a hydrogen-to-oil volume ratio of 350:1.
[0048] The pre-vulcanization process is as follows: Pre-vulcanizing oil is introduced at 130℃, and vulcanization is carried out at a constant temperature for 1 hour. The temperature is then increased to 230℃ at a rate of 20℃ / h, and vulcanized at a constant temperature for 9 hours. The temperature is then increased to 340℃ at a rate of 15℃ / h, and vulcanized at a constant temperature for 6 hours. Finally, the temperature is allowed to drop naturally to 320℃, and the pre-vulcanization process is completed.
[0049] The evaluation reaction conditions were: operating pressure 4.0 MPa, reaction temperature 320 °C, and volume hourly space velocity (VHSV) 3.0 h⁻¹. -1 The hydrogen-to-oil ratio was 200:1, and the evaluation results are shown in Table 1.
[0050] Table 1.
[0051]
[0052]
[0053] In Examples 4-7, two fixed-bed reactors connected in series were used for the reaction. According to the order of contact with the feedstock oil, the first fixed-bed reactor was the low-temperature zone, and the second fixed-bed reactor was the high-temperature zone.
[0054] Example 4
[0055] Catalyst A4 was loaded in the low-temperature zone and catalyst B2 was loaded in the high-temperature zone. Activity evaluation was conducted using a pre-hydrogenation followed by desulfurization approach. The NiO / MoO3 ratio in the low-temperature zone was 3.1 compared to that in the high-temperature zone.
[0056] The feedstock used for evaluation was the same as in Example 3, and the pre-sulfurization conditions of the catalyst were the same as in Example 3.
[0057] Low-temperature reaction conditions: operating pressure 4.0 MPa, reaction temperature 220℃, volume hourly space velocity (VHSV) 1.5 h⁻¹. -1 The hydrogen-to-oil ratio was 200:1. The desulfurization rate and aromatic saturation rate were calculated based on the changes in sulfur content and benzothiophene sulfide content in the diesel fuel at the inlet and outlet of the low-temperature zone.
[0058] High-temperature reaction conditions: operating pressure 4.0 MPa, reaction temperature 335℃, volume hourly space velocity (VHSV) 1.5 h⁻¹. -1 The hydrogen-to-oil ratio was 200:1. The reaction temperature in the high-temperature zone was gradually adjusted to achieve a final temperature below 10 ppm sulfur content in the product. The total desulfurization rate was calculated based on the change in sulfur content in the diesel fuel at the inlet of the low-temperature zone and the outlet of the high-temperature zone. The reaction results are shown in Table 2.
[0059] Example 5
[0060] Catalyst A2 was loaded in the low-temperature zone and catalyst B1 was loaded in the high-temperature zone. Activity evaluation was conducted using a pre-hydrogenation followed by desulfurization approach. The NiO / MoO3 ratio in the low-temperature zone was 9.0 compared to that in the high-temperature zone.
[0061] The feedstock used for evaluation was the same as in Example 3, and the pre-sulfurization conditions of the catalyst were the same as in Example 3.
[0062] Low-temperature reaction conditions: operating pressure 4.0 MPa, reaction temperature 240℃, volume hourly space velocity (VHSV) 1.5 h⁻¹. -1The hydrogen-to-oil ratio was 200:1. The desulfurization rate and aromatic saturation rate were calculated based on the changes in sulfur content and benzothiophene sulfide content in the diesel fuel at the inlet and outlet of the low-temperature zone.
[0063] High-temperature reaction conditions: operating pressure 4.0 MPa, reaction temperature 345℃, volume hourly space velocity (VHSV) 1.5 h⁻¹. -1 The hydrogen-to-oil ratio was 200:1. The reaction temperature in the high-temperature zone was gradually adjusted to achieve a final temperature below 10 ppm sulfur content in the product. The total desulfurization rate was calculated based on the change in sulfur content in the diesel fuel at the inlet of the low-temperature zone and the outlet of the high-temperature zone. The reaction results are shown in Table 2.
[0064] Example 6
[0065] Catalyst A3 was loaded in the low-temperature zone and catalyst B1 was loaded in the high-temperature zone. Activity evaluation was conducted using a pre-hydrogenation followed by desulfurization approach. The NiO / MoO3 ratio in the low-temperature zone was 18.7 compared to that in the high-temperature zone.
[0066] The feedstock used for evaluation was the same as in Example 3, and the pre-sulfurization conditions of the catalyst were the same as in Example 3.
[0067] Low-temperature reaction conditions: operating pressure 4.0 MPa, reaction temperature 280℃, volume hourly space velocity (VHSV) 1.5 h⁻¹. -1 The hydrogen-to-oil ratio was 200:1. The desulfurization rate and aromatic saturation rate were calculated based on the changes in sulfur content and benzothiophene sulfide content in the diesel fuel at the inlet and outlet of the low-temperature zone.
[0068] High-temperature reaction conditions: operating pressure 4.0 MPa, reaction temperature 355℃, volume hourly space velocity (VHSV) 1.5 h⁻¹. -1 The hydrogen-to-oil ratio was 200:1. The reaction temperature in the high-temperature zone was gradually adjusted to achieve a final temperature below 10 ppm sulfur content in the product. The total desulfurization rate was calculated based on the change in sulfur content in the diesel fuel at the inlet of the low-temperature zone and the outlet of the high-temperature zone. The reaction results are shown in Table 2.
[0069] Example 7
[0070] Catalyst A1 was loaded in the low-temperature zone and catalyst B3 was loaded in the high-temperature zone. Activity evaluation was conducted using a pre-hydrogenation followed by desulfurization approach. The NiO / MoO3 ratio in the low-temperature zone was 1.3 compared to that in the high-temperature zone.
[0071] The feedstock used for evaluation was the same as in Example 3, and the pre-sulfurization conditions of the catalyst were the same as in Example 3.
[0072] Low-temperature reaction conditions: operating pressure 4.0 MPa, reaction temperature 260℃, volume hourly space velocity (VHSV) 1.5 h⁻¹. -1 The hydrogen-to-oil ratio was 200:1. The desulfurization rate and aromatic saturation rate were calculated based on the changes in sulfur content and benzothiophene sulfide content in the diesel fuel at the inlet and outlet of the low-temperature zone.
[0073] High-temperature reaction conditions: operating pressure 4.0 MPa, reaction temperature 370℃, volume hourly space velocity (VHSV) 1.5 h⁻¹. -1 The hydrogen-to-oil ratio was 200:1. The reaction temperature in the high-temperature zone was gradually adjusted to achieve a final temperature below 10 ppm sulfur content in the product. The total desulfurization rate was calculated based on the change in sulfur content in the diesel fuel at the inlet of the low-temperature zone and the outlet of the high-temperature zone. The reaction results are shown in Table 2.
[0074] Comparative Example 1
[0075] The reactor configuration was the same as in Example 7, and the activity evaluation was conducted using a combination of low-temperature and high-temperature zones. However, for comparison, both reaction zones were filled with A1 catalyst.
[0076] The feedstock used for evaluation was the same as in Example 3, and the pre-sulfurization conditions of the catalyst were the same as in Example 3.
[0077] Low-temperature reaction conditions: operating pressure 4.0 MPa, reaction temperature 260℃, volume hourly space velocity (VHSV) 1.5 h⁻¹. -1 The hydrogen-to-oil ratio was 200:1. The desulfurization rate and aromatic saturation rate were calculated based on the changes in sulfur content and benzothiophene sulfide content in the diesel fuel at the inlet and outlet of the low-temperature zone.
[0078] High-temperature reaction conditions: operating pressure 4.0 MPa, reaction temperature 395℃, volume hourly space velocity (VHSV) 1.5 h⁻¹. -1 The hydrogen-to-oil ratio was 200:1. The reaction temperature in the high-temperature zone was gradually adjusted to achieve a final temperature below 10 ppm sulfur content in the product. The total desulfurization rate was calculated based on the change in sulfur content in the diesel fuel at the inlet of the low-temperature zone and the outlet of the high-temperature zone. The reaction results are shown in Table 2.
[0079] Comparative Example 2
[0080] The reactor configuration was the same as in Example 7, and the activity evaluation was conducted using a combination of low-temperature and high-temperature zones. However, for comparison, both reaction zones were filled with B4 catalyst.
[0081] The feedstock used for evaluation was the same as in Example 3, and the pre-sulfurization conditions of the catalyst were the same as in Example 3.
[0082] Low-temperature reaction conditions: operating pressure 4.0 MPa, reaction temperature 290℃, volume hourly space velocity (VHSV) 1.5 h⁻¹. -1 The hydrogen-to-oil ratio was 200:1. The desulfurization rate and aromatic saturation rate were calculated based on the changes in sulfur content and benzothiophene sulfide content in the diesel fuel at the inlet and outlet of the low-temperature zone.
[0083] High-temperature reaction conditions: operating pressure 4.0 MPa, reaction temperature 410℃, volume hourly space velocity (VHSV) 1.5 h⁻¹. -1The hydrogen-to-oil ratio was 200:1. The reaction temperature in the high-temperature zone was gradually adjusted to achieve a final product sulfur content of less than 10 ppm. The total desulfurization rate was calculated based on the change in sulfur content in the diesel fuel at the inlet of the low-temperature zone and the outlet of the high-temperature zone. The reaction results are shown in Table 2.
[0084] Table 2.
[0085]
[0086]
Claims
1. A process for the hydrodesulfurization reaction of diesel fuel, characterized in that, The process involves first passing the diesel feedstock through a low-temperature zone for a hydrogenation-based aromatic saturation reaction, followed by a high-temperature zone for a desulfurization-based reaction. The low-temperature zone has a reaction temperature of 210-320℃, a desulfurization rate of less than 50%, and a dibenzothiophene sulfide saturation rate of greater than 50%. The high-temperature zone has a reaction temperature of 320-450℃, and after passing through the high-temperature zone, the total desulfurization rate of the feedstock is not less than 99.9%.
2. The process method according to claim 1, characterized in that, The reaction temperature in the low-temperature zone is 210-300℃.
3. The process method according to claim 2, characterized in that, The reaction temperature in the low-temperature zone is 220-280℃.
4. The process method according to claim 1, characterized in that, Based on the aromatic ring saturation rate of dibenzothiophene compounds, the reaction temperature in the low-temperature region allows the aromatic ring saturation rate to exceed 50%.
5. The process method according to claim 4, characterized in that, Based on the aromatic ring saturation rate of dibenzothiophene compounds, the reaction temperature in the low-temperature region allows the aromatic ring saturation rate to exceed 70%.
6. The process method according to claim 1, characterized in that, Using the total desulfurization rate of the raw materials as the standard, the reaction temperature in the low-temperature zone makes the desulfurization rate of the raw materials less than 50%.
7. The process method according to claim 1, characterized in that, Using the total desulfurization rate of the raw materials as the standard, the reaction temperature in the low-temperature zone makes the desulfurization rate of the raw materials less than 75%.
8. The process method according to claim 1, characterized in that, Catalyst I is used in the low-temperature zone and catalyst II is used in the high-temperature zone. Under the same conditions, the aromatic ring saturation activity of catalyst I is more than 10% higher than that of catalyst II used in the high-temperature zone. The aromatic ring saturation activity is based on the saturation rate of dibenzothiophene compounds in the raw materials before and after the reaction.
9. The process method according to claim 1, characterized in that, The reaction temperature in the high-temperature zone is 325-420℃.
10. The process method according to claim 1, characterized in that, The reaction temperature in the high-temperature zone is 330-380℃.
11. The process method according to claim 8, characterized in that, Under the same conditions, the desulfurization activity of catalyst II is more than 20% higher than that of catalyst I. The desulfurization activity is based on the desulfurization rate of the raw materials before and after the reaction.
12. The process method according to claim 8 or 11, characterized in that, Catalyst I and Catalyst II use alumina or modified alumina as a support and nickel oxide and molybdenum oxide as active components. The weight ratio of NiO / MoO3 in Catalyst I is 1.05-20.0 times that in Catalyst II.
13. The process method according to claim 12, characterized in that, Based on the weight of the catalyst, the catalyst I contains 10%-35% molybdenum oxide and 4%-15% nickel oxide.
14. The process method according to claim 13, characterized in that, The weight ratio of NiO / MoO3 in catalyst I is 0.160-0.
700.
15. The process method according to claim 12, characterized in that, Based on the weight of the catalyst, the catalyst II contains 12%-33% molybdenum oxide and 0.9%-3.9% nickel oxide.
16. The process method according to claim 15, characterized in that, The weight ratio of NiO / MoO3 in catalyst II is 0.030-0.159.