Distillate oil hydrogenation method

Abstract

A distillate oil hydrogenation method comprises a reaction stage and an online carbon deposit cleaning stage, and in the reaction stage, distillate oil and hydrogen are mixed and then enter a fixed bed selective hydrodesulfurization reaction zone to be subjected to a contact reaction with a hydrotreating catalyst. The low-pressure and high-temperature operation conditions are adopted in the reaction stage, the hydrodesulfurization selectivity is improved, the hydrogen consumption is reduced, meanwhile, the online carbon deposit cleaning process is added, and the problem that the activity stability of the hydrogenation catalyst is poor due to carbon deposit is solved. The method provided by the invention has the characteristics of long-period stable production and low hydrogen consumption.

Description

Technical Field

[0001] The invention relates to the field of hydrocarbon oil raw material processing, and in particular to a distillate oil hydrogenation method. Background Art

[0002] As global environmental problems continue to intensify, environmental regulations have been introduced at home and abroad to impose stricter restrictions on the sulfur content of automotive fuel oil and marine fuel oil. When hydrogenating hydrocarbon oil raw materials, especially deep hydrodesulfurization, there will be high hydrogen consumption, resulting in high processing costs. Therefore, in the process of oil hydrorefining, how to optimize the process conditions according to product requirements, improve the selectivity of hydrodesulfurization, and thus reduce hydrogen consumption to a certain extent, is a problem that needs to be solved at present.

[0003] CN112300833A discloses a method for producing low-sulfur residual marine fuel, which comprises sequentially loading a hydroprotection catalyst, a hydrodemetallization catalyst and a hydrodemetallization desulfurization catalyst in a residual oil hydrotreating device along the logistics direction. The method improves the catalyst grading to produce low-sulfur residual marine fuel at low cost and in a long period.

[0004] CN 108728162A discloses a method for producing a raw material rich in monocyclic aromatic hydrocarbons, comprising cutting diesel raw oil into a light diesel fraction and a heavy diesel fraction, mixing the heavy diesel fraction with hydrogen, contacting the heavy diesel fraction with a hydrofining catalyst I in a first reaction zone, and performing hydrodesulfurization, hydrodenitrogenation and selective hydrodearomatization reactions under hydrogenation reaction conditions; the light diesel fraction is mixed with the effluent of the first reaction zone and then enters a second reaction zone to contact the hydrofining catalyst II, and further performs hydrodesulfurization, hydrodenitrogenation and selective hydrodearomatization reactions under hydrogenation reaction conditions. The method adopts two reaction zones and reduces the hydrogen consumption of the hydrogenation process by catalyst grading. Summary of the invention

[0005] The invention aims to solve the technical problem of how to improve the selectivity of distillate oil hydrodesulfurization to reduce hydrogen consumption.

[0006] The reactions involved in the oil hydrofining process mainly include hydrodesulfurization, hydrodenitrogenation and aromatic saturation, etc., and there are usually different reaction paths in the hydrogenation reaction, which will lead to obvious differences in the hydrogen consumption of different hydrogenation reactions or different reaction paths of the same hydrogenation reaction. For example, the hydrodesulfurization reaction includes a direct desulfurization path and a hydrogenation-first-desulfurization path, in which the former does not need to go through aromatic saturation to directly remove sulfur atoms, while the latter needs to first saturate the aromatic ring next to the sulfur atom and then remove the sulfur atom, so the hydrogen consumption of the former is lower than that of the latter. After a large number of experiments and systematic thinking, the inventors of the present invention have found that within the conventional operating conditions of distillate oil, when the hydrodesulfurization rate is usually increased, the degree of aromatic saturation will also increase, resulting in an increase in hydrogen consumption in the hydrodesulfurization process. However, when the distillate oil hydrogenation process is not within the conventional operating conditions, the hydrogen consumption of the distillate oil hydrodesulfurization process will be reduced when the reaction is adjusted in the aromatic saturation thermodynamic equilibrium control area. When operating in this region, the aromatic saturation rate is controlled by thermodynamic equilibrium, and the aromatic saturation rate will decrease with the increase of reaction temperature, but the hydrodesulfurization rate will increase with the increase of reaction temperature, so the purpose of improving the selectivity of hydrodesulfurization rate and reducing the hydrogen consumption in the hydrodesulfurization process can be achieved. However, the inventors further found that the aromatic saturation thermodynamic equilibrium control zone has the characteristics of low pressure and high temperature. When operating in the aromatic saturation thermodynamic equilibrium control zone, the activity stability of the catalyst will be poor, thereby failing to achieve the purpose of long-term operation.

[0007] In order to achieve the above object, the present invention provides a distillate oil hydrogenation method, the method comprising:

[0008] Reaction stage: The distillate oil is mixed with hydrogen and enters the fixed bed selective hydrodesulfurization reaction zone to contact and react with the hydrotreating catalyst. The reaction effluent enters the gas-liquid separation zone for gas-liquid separation, and the liquid phase is used as the hydrogenated oil. The reaction conditions of the selective hydrodesulfurization reaction zone are: hydrogen partial pressure 0.1-5.9MPa, reaction temperature 390-460℃, hydrogen-oil volume ratio 800-2500, volume space velocity 0.1-4.0h -1 ;

[0009] Online cleaning carbon deposition stage: distillate oil, circulating oil and hydrogen are mixed together and enter the fixed bed selective hydrodesulfurization reaction zone to contact with the hydrotreating catalyst. The reaction effluent enters the gas-liquid separation zone for gas-liquid separation. At least part of the liquid phase is returned to the raw material buffer tank as circulating oil. The reaction conditions of the selective hydrodesulfurization reaction zone are: hydrogen partial pressure of 6.0-12.0MPa, reaction temperature of 350-460℃, hydrogen-oil volume ratio of 200-2500, volume space velocity of 0.1-4.0h -1 .

[0010] In the present invention, the initial distillation point of the distillate oil is in the range of 60-350°C, and the final distillation point is in the range of 180-600°C.

[0011] In one embodiment of the present invention, the distillate oil is selected from one or more of straight-run naphtha, straight-run diesel, straight-run wax oil, catalytic gasoline, catalytic diesel, catalytic slurry, coal tar, coker gasoline, coker diesel, coker wax oil, and deasphalted oil.

[0012] In a preferred embodiment of the present invention, the distillate oil is selected from one or more of catalytic gasoline, catalytic diesel, catalytic slurry oil, coal tar, coker diesel, and coker wax oil.

[0013] In one embodiment of the present invention, the reaction conditions of the selective hydrodesulfurization reaction zone in the reaction stage are: hydrogen partial pressure 1.0-5.0 MPa, reaction temperature 400-450°C, hydrogen-to-oil volume ratio 1000-2000, volume space velocity 0.2-3.0 h -1 .

[0014] The present invention controls the reaction stage of the distillate oil to react in the low-pressure and high-temperature aromatic saturation thermodynamic equilibrium control zone to improve the selectivity of the direct desulfurization reaction path. In a preferred case, during the reaction stage of the present invention, the hydrodesulfurization rate is ≮90%, and the hydrogen mass fraction of the hydrogenated oil differs from the hydrogen mass fraction of the raw material by ≯0.7 mass %. More preferably, during the reaction stage, the hydrodesulfurization rate is ≮90%, and the hydrogen mass fraction of the hydrogenated oil differs from the hydrogen mass fraction of the raw material by ≯0.6 mass %.

[0015] At the same time, in order to overcome the problem of poor catalyst activity stability under low-pressure and high-temperature operating conditions, the present invention adopts an online carbon deposit cleaning method. The online carbon deposit cleaning can partially eliminate the catalyst carbon deposits formed during low-pressure and high-temperature operation and slow down the deactivation rate of the catalyst.

[0016] In one embodiment of the present invention, the duration of the online cleaning of carbon deposits is 1-10 days.

[0017] In one embodiment of the present invention, when the hydrodesulfurization rate of the hydrogenated oil is less than 90%, the online cleaning of carbon deposits is started; or, the online cleaning of carbon deposits is started once every 1-6 months.

[0018] There is no particular limitation on the type and number of fixed bed reactors used in the selective hydrodesulfurization reaction zone. Preferably, the fixed bed reactors can be selected from one or more of an upflow reactor and a downflow reactor.

[0019] In one embodiment of the present invention, the hydroprocessing catalyst comprises one or more catalysts, each of which independently contains a carrier and 0-35 mass % of an active metal component, wherein the active metal component is selected from at least one of Group VIB and / or Group VIIII non-noble metal elements.

[0020] Preferably, the active metal component is selected from at least one of a nickel-tungsten combination, a nickel-tungsten-cobalt combination, a nickel-molybdenum combination and a cobalt-molybdenum combination.

[0021] More preferably, in each of the hydroprocessing catalysts, the content of the active metal component calculated as metal oxide is 0.05-30% by mass.

[0022] Preferably, in each of the hydroprocessing catalysts, the carrier is independently selected from at least one of alumina, silica and titania.

[0023] Preferably, each of the hydroprocessing catalysts independently further contains at least one promoter element selected from boron, germanium, zirconium, phosphorus, chlorine and fluorine.

[0024] Preferably, in each of the hydroprocessing catalysts, the total content of the promoter elements, calculated as elements, is 0-10% by mass.

[0025] In one embodiment of the present invention, the average particle size of each of the hydroprocessing catalysts is independently 0.5-50 mm, and the bulk density of each of the hydroprocessing catalysts is independently 0.3-1.2 g / cm 3 The average pore size of each of the hydroprocessing catalysts is independently 6-30 nm, and the specific surface area of ​​each of the hydroprocessing catalysts is independently 50-400 m 2 / g.

[0026] In a preferred embodiment, the average pore volume of each of the hydroprocessing catalysts is independently 0.1-5 mL / g.

[0027] The gas-liquid separation zone is well known to those skilled in the art and may include a hot high fractionator, a cold high fractionator, a hot low fractionator, a cold low fractionator, a stripping tower and a distillation tower, etc., and its operating conditions are also well known to those skilled in the art.

[0028] Unless otherwise specified, the reaction pressure in the present invention is expressed in the form of hydrogen partial pressure.

[0029] Unless otherwise specified, the pressures described in the present invention are gauge pressures.

[0030] Features of the present invention: The present invention controls the reaction stage of distillate oil hydrogenation to be carried out in the low-pressure and high-temperature aromatic saturation thermodynamic equilibrium control zone, thereby improving the hydrodesulfurization selectivity and reducing the hydrogen consumption. At the same time, an online cleaning carbon deposition process is added, thereby overcoming the problem of poor activity stability of the hydrogenation catalyst caused by carbon deposition. The distillate oil hydrogenation method of the present invention has the characteristics of long-term stable production, low hydrogen consumption and low cost. DETAILED DESCRIPTION

[0031] The present invention is further described below in conjunction with the examples, but the present invention is not limited thereto. In the following examples, unless otherwise specified, all raw materials used can be obtained from commercial channels.

[0032] The reactions in the following examples were carried out in a fixed bed hydroprocessing unit.

[0033] The raw materials used in the following examples and their properties are shown in Table 1, wherein raw material A is catalytic diesel and raw material B is straight-run wax oil.

[0034] The hydroprocessing catalysts used in the following examples are all produced by the Changling Catalyst Plant of Sinopec Catalyst Branch. Their physical and chemical properties are shown in Table 2.

[0035] Table 1

[0036]

[0037]

[0038] Table 2

[0039] catalyst A B <![CDATA[MO3, mass %]]> 15.0 17.5 CoO, mass% 4.0 4.5 Average pore volume, mL / g 0.50 0.45 <![CDATA[Specific surface area, m 2 / g]]> 175 190 <![CDATA[Bulk density, g / cm 3 > 0.65 0.67 Average particle size, mm 1.1 1.1

[0040] Example 1

[0041] The raw material A was hydrogenated in the selective hydrodesulfurization reaction zone, and the catalyst used was A. The process conditions were shown in Table 3. After 10 days of operation, the desulfurization rate was 99.6%, and the difference between the hydrogen mass fraction of the hydrogenated oil and the hydrogen mass fraction of the raw material, that is, the difference between the hydrogen mass fraction before and after hydrogenation was 0.41 mass%. After that, carbon cleaning was carried out each time the desulfurization rate dropped to 90%, and each cleaning lasted for 5 days. During the cleaning period, the weight ratio of the circulating oil to the fresh oil was 1:1, the hydrogen partial pressure was 8.0 MPa, the reaction temperature was 380°C, and the other process conditions remained unchanged. After each cleaning, the original conditions were restored and the operation was continued. After one year of operation (excluding the carbon cleaning time), the desulfurization rate was 95.6%, and the difference between the hydrogen mass fraction before and after hydrogenation was 0.48 mass%. The specific results are listed in Table 3.

[0042] Example 2

[0043] The raw material B was hydrotreated in the selective hydrodesulfurization reaction zone, and the catalyst used was B. The process conditions were shown in Table 3. After 10 days of operation, the desulfurization rate was 99.5%, and the difference in hydrogen mass fraction before and after hydrogenation was 0.53% by mass. Thereafter, carbon deposit cleaning was performed once every month of operation, and each cleaning lasted for 5 days. During the cleaning period, the weight ratio of circulating oil to fresh oil was 1:1, the hydrogen partial pressure was 10.0 MPa, the reaction temperature was 380°C, and the other process conditions remained unchanged. After each cleaning, the original conditions were restored and the operation was continued. After 14 months of operation (excluding the carbon deposit cleaning time), the desulfurization rate was 93.8%, and the difference in hydrogen mass fraction before and after hydrogenation was 0.62% by mass. The specific results are listed in Table 3.

[0044] Comparative Example 1

[0045] Raw material A was subjected to conventional hydrotreatment, the catalyst used was A, and the process conditions were as shown in Table 3. After 10 days of operation, the desulfurization rate was 99.6%, and the difference in hydrogen mass fraction before and after hydrogenation was 1.20 mass%. The specific results are listed in Table 3. Compared with Example 1, it can be seen that the present invention can significantly reduce the hydrogen consumption in the hydrodesulfurization process at the same desulfurization rate.

[0046] Comparative Example 2

[0047] Raw material B was subjected to conventional hydrotreatment, the catalyst used was B, and the process conditions were as shown in Table 3. After 10 days of operation, the desulfurization rate was 99.5%, and the difference in hydrogen mass fraction before and after hydrogenation was 0.96 mass%. The specific results are listed in Table 3. Compared with Example 2, it can be seen that the present invention can significantly reduce the hydrogen consumption in the hydrodesulfurization process at the same desulfurization rate.

[0048] Comparative Example 3

[0049] The raw material A was hydrotreated in the selective hydrodesulfurization reaction zone, the catalyst used was A, and the process conditions were shown in Table 3. After 10 days of operation, the desulfurization rate was 99.6%, and the difference in hydrogen mass fraction before and after hydrogenation was 0.41 mass%. After continuing to operate for 4 months, the desulfurization rate was 88.6%, and the difference in hydrogen mass fraction before and after hydrogenation was 0.49 mass%. The specific results are listed in Table 3. Compared with Example 1, it can be seen that the carbon cleaning during operation can significantly extend the operation cycle.

[0050] Table 3

[0051]

[0052] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A distillate oil hydrogenation method comprising: Reaction stage: The distillate oil is mixed with hydrogen and enters the fixed bed selective hydrodesulfurization reaction zone to contact and react with the hydrotreating catalyst. The reaction effluent enters the gas-liquid separation zone for gas-liquid separation, and the liquid phase is used as the hydrogenated oil. The reaction conditions of the selective hydrodesulfurization reaction zone are: hydrogen partial pressure 0.1-5.9MPa, reaction temperature 390-460℃, hydrogen-oil volume ratio 800-2500, volume space velocity 0.1-4.0h -1 ; Online cleaning carbon deposition stage: distillate oil, circulating oil and hydrogen are mixed together and enter the fixed bed selective hydrodesulfurization reaction zone to contact with the hydrotreating catalyst. The reaction effluent enters the gas-liquid separation zone for gas-liquid separation. At least part of the liquid phase is returned to the raw material buffer tank as circulating oil. The reaction conditions of the selective hydrodesulfurization reaction zone are: hydrogen partial pressure of 6.0-12.0MPa, reaction temperature of 350-460℃, hydrogen-oil volume ratio of 200-2500, volume space velocity of 0.1-4.0h -1 .

2. The method according to claim 1, characterized in that The reaction conditions of the selective hydrodesulfurization reaction zone in the reaction stage are: hydrogen partial pressure 1.0-5.0MPa, reaction temperature 400-450℃, hydrogen-oil volume ratio 1000-2000, volume space velocity 0.2-3.0h -1 .

3. The method according to claim 1, characterized in that: During the reaction stage, the hydrodesulfurization rate is ≮90%, and the difference between the hydrogen mass fraction of the hydrogenated oil and the hydrogen mass fraction of the raw material is ≯0.7 mass %.

4. The method according to claim 1, characterized in that During the reaction stage, the hydrodesulfurization rate is ≮90%, and the hydrogen mass fraction of the hydrogenated oil differs from that of the raw material by ≯0.6 mass %.

5. The method according to claim 1, characterized in that The duration of the online cleaning carbon deposition stage is 1-10 days.

6. The method according to claim 1, characterized in that When the hydrodesulfurization rate of the hydrogenated oil is less than 90%, start the online cleaning of carbon deposits; or, start the online cleaning of carbon deposits once every 1-6 months.

7. The method according to claim 1, characterized in that The initial boiling point of the distillate oil is within the range of 60-350°C, and the final boiling point is within the range of 180-600°C.

8. The method according to claim 1, characterized in that The distillate oil is selected from one or more of straight-run naphtha, straight-run diesel, straight-run wax oil, catalytic gasoline, catalytic diesel, catalytic slurry oil, coal tar, coker gasoline, coker diesel, coker wax oil, and deasphalted oil; Preferably, the distillate oil is selected from one or more of catalytic gasoline, catalytic diesel, catalytic slurry oil, coal tar, coker diesel, and coker wax oil.

9. The method according to claim 1, characterized in that: The hydroprocessing catalyst comprises one or more, and each of them independently contains a carrier and 0-35 mass % of an active metal component, wherein the active metal component is selected from at least one of the non-precious metal elements of Group VIB and / or Group VIIII; Preferably, the active metal component is selected from at least one of a nickel-tungsten combination, a nickel-tungsten-cobalt combination, a nickel-molybdenum combination and a cobalt-molybdenum combination; Preferably, in each of the hydroprocessing catalysts, the content of the active metal component calculated as metal oxide is 0.05-30 mass %; Preferably, in each of the hydroprocessing catalysts, the carrier is independently selected from at least one of alumina, silica and titania.

10. The method according to claim 9, characterized in that The average particle size of each of the hydroprocessing catalysts is independently 0.5-50 mm, and the bulk density of each of the hydroprocessing catalysts is independently 0.3-1.2 g / cm 3 The average pore size of each of the hydroprocessing catalysts is independently 6-30 nm, and the specific surface area of ​​each of the hydroprocessing catalysts is independently 50-400 m 2 / g.

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