A distillate hydroprocessing method

Abstract

The application discloses a distillate oil hydrogenation method, which comprises a reaction stage and an online cleaning carbon deposition stage. In the reaction stage, the distillate oil is mixed with hydrogen and then enters a fixed-bed selective hydrodesulfurization reaction zone to be reacted with a hydroprocessing catalyst. The application adopts low-pressure high-temperature operating conditions in the reaction stage, improves the hydrodesulfurization selectivity, reduces hydrogen consumption, increases the online cleaning carbon deposition process, and overcomes the problem of poor activity stability of the hydrogenation catalyst caused by carbon deposition. The method has the characteristics of long-period stable production and low hydrogen consumption.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of hydrocarbon oil feedstock processing, and in particular to a distillate oil hydrogenation method. BACKGROUND

[0002] With the increasing global environmental problems, environmental protection regulations have been introduced at home and abroad to more strictly limit the sulfur content of vehicle fuel oil and marine fuel oil. When hydroprocessing hydrocarbon oil feedstock, especially deep hydrodesulfurization, there is a problem of high hydrogen consumption, resulting in high processing cost. Therefore, in the process of oil hydrofining, how to optimize the process conditions according to the product requirements, improve the selectivity of hydrodesulfurization, and thus reduce the hydrogen consumption to a certain extent, is a problem to be solved at present.

[0003] CN112300833A discloses a method for producing low-sulfur residual marine fuel, which comprises sequentially filling a hydrogenation protection catalyst, a hydrodemetallization catalyst and a hydrodemetallization and desulfurization catalyst in the flow direction in a residual oil hydroprocessing device. The method is improved by catalyst grading, thereby producing low-sulfur residual marine fuel at low cost and for a long period.

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

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

[0006] The reactions involved in oil hydrofining process mainly include hydrodesulfurization, hydrodenitrogenation and aromatic saturation, etc., and different reaction paths exist in hydrogenation reaction, which will result in obvious difference in hydrogen consumption of different hydrogenation reactions or different reaction paths of the same hydrogenation reaction. For example, the hydrodesulfurization reaction includes direct desulfurization path and hydrogenation and then desulfurization path, wherein the former does not need to pass through aromatic saturation and directly removes sulfur atom, and the latter needs to saturate aromatic ring beside sulfur atom and then remove sulfur atom, so the hydrogen consumption of the former is lower than that of the latter. The inventors of the present application find through a large number of experiments and systematic thinking and summarization that within the range of conventional operating conditions of distillate oil, the aromatic saturation degree will increase when the hydrodesulfurization rate increases, resulting in increase in hydrogen consumption of the hydrodesulfurization process. However, when the distillate oil hydrogenation process is not within the range of conventional operating conditions, and the reaction is adjusted within the aromatic saturation thermodynamic equilibrium control zone, the hydrogen consumption of the distillate oil hydrodesulfurization process will be reduced. When operating within the zone, the aromatic saturation rate is controlled by thermodynamic equilibrium, and the aromatic saturation rate will decrease with increase in reaction temperature, but the hydrodesulfurization rate will increase with increase in reaction temperature, so the purpose of improving the selectivity of hydrodesulfurization rate and reducing the hydrogen consumption of the hydrodesulfurization process can be achieved. However, the inventors further find that the aromatic saturation thermodynamic equilibrium control zone has the characteristics of low pressure and high temperature, and when operating within the aromatic saturation thermodynamic equilibrium control zone, the activity stability of the catalyst will be poor, so the purpose of long-period operation cannot be achieved.

[0007] In order to achieve the above purpose, the present application provides a distillate oil hydrogenation method, which comprises:

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

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

[0010] In the present application, the initial boiling point of the distillate oil is in the range of 60-350 ℃, and the final boiling point is in the range of 180-600 ℃.

[0011] In one embodiment of the present application, the distillate oil is selected from one or more of straight-run naphtha, straight-run diesel, straight-run gas oil, catalytic gasoline, catalytic diesel, catalytic slurry oil, coal tar, coking gasoline, coking diesel, coking gas oil, de-asphalted oil.

[0012] In one preferred embodiment of the present application, the distillate oil is selected from one or more of catalytic gasoline, catalytic diesel, catalytic slurry oil, coal tar, coking diesel, coking gas oil.

[0013] In one embodiment of the present application, the reaction conditions of the selective hydrodesulfurization reaction zone of 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 application controls the reaction stage of the distillate oil to be carried out in the aromatic saturation thermodynamic equilibrium control zone at low pressure and high temperature, improves the selectivity of the direct desulfurization reaction path, and in the preferred case, the hydrogen desulfurization rate in the reaction stage is ≧ 90%, while the hydrogen mass fraction of the hydrogenated oil and the hydrogen mass fraction of the raw material differ by ≯ 0.7 mass%. Further preferably, the hydrogen desulfurization rate in the reaction stage is ≧ 90%, while the hydrogen mass fraction of the hydrogenated oil and the hydrogen mass fraction of the raw material differ by ≯ 0.6 mass%.

[0015] Meanwhile, in order to overcome the problem of poor activity stability of the catalyst under the operating conditions of low pressure and high temperature, the present application adopts the method of online cleaning of the coke. The online cleaning of the coke can partially eliminate the catalyst coke formed under the operating conditions of low pressure and high temperature, and delay the deactivation rate of the catalyst.

[0016] In one embodiment of the present application, the duration of the online cleaning of the coke stage is 1-10 days.

[0017] In one embodiment of the present application, when the hydrogen desulfurization rate of the hydrogenated oil is < 90%, the online cleaning of the coke is started; or, the online cleaning of the coke is started once every 1-6 months.

[0018] The fixed bed reactor type and number adopted by the selective hydrodesulfurization reaction zone are not particularly limited, and preferably, can be selected from one or more of the upflow reactor and the downflow reactor.

[0019] In one embodiment of the present application, the hydrotreating catalyst comprises one or more, and each independently contains a carrier and 0-35 mass% of an active metal component selected from at least one of the VIB group and / or the non-noble metal element of the VIIII group.

[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, the content of the active metal component in each of the hydroprocessing catalysts is 0.05-30 mass% as metal oxide.

[0022] Preferably, the support in each of the hydroprocessing catalysts 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 auxiliary element selected from boron, germanium, zirconium, phosphorus, chlorine and fluorine.

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

[0025] In one embodiment of the present application, the average particle diameter of each of the hydroprocessing catalysts is independently 0.5-50 mm, the bulk density of each of the hydroprocessing catalysts is independently 0.3-1.2 g / cm 3 , the average pore diameter 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 case, 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 can include a hot high separator, a cold high separator, a hot low separator, a cold low separator, a stripper column and a fractionating column, etc., and the operating conditions thereof are also well known to those skilled in the art.

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

[0029] Unless otherwise specified, the pressure in the present application is all expressed in the form of gauge pressure.

[0030] The present application has the following features: the reaction stage of the distillate oil hydrogenation in the present application is controlled to be carried out in the aromatic saturation thermodynamic equilibrium control zone at low pressure and high temperature, thereby improving the hydrogen desulfurization selectivity, reducing the hydrogen consumption, increasing the on-line cleaning of the carbon deposition process, and overcoming the problem of poor activity stability of the hydrogenation catalyst caused by carbon deposition. The distillate oil hydrogenation method of the present application has the characteristics of long-period stable production, low hydrogen consumption and low cost. DETAILED DESCRIPTION

[0031] The application will be further described in connection with the following examples without thereby limiting the application. In the following examples, the various raw materials used are commercially available unless otherwise specified.

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

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

[0034] The hydrotreating catalysts used in the following examples were produced by Sinopec Catalyst Branch Company Changling Catalyst Factory, and their physicochemical properties are shown in Table 2.

[0035] Table 1

[0036]

[0037]

[0038] Table 2

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

[0040] Example 1

[0041] Raw material A was hydrotreated in a selective hydrodesulfurization reaction zone using catalyst A, and the process conditions are shown in Table 3. After 10 days of operation, the desulfurization rate was 99.6%, and the difference in hydrogen mass fraction between the hydrotreated oil and the raw material, i.e., the difference in hydrogen mass fraction before and after hydrogenation, was 0.41 mass%. Thereafter, a carbon deposition cleaning was performed once the desulfurization rate decreased to 90%, and each cleaning lasted for 5 days. During the cleaning, 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 for continued operation, and the continued operation lasted for 1 year (without counting the carbon deposition cleaning time). The desulfurization rate was 95.6%, and the difference in hydrogen mass fraction before and after hydrogenation was 0.48 mass%. The specific results are shown in Table 3.

[0042] Example 2

[0043] The feedstock B was subjected to hydrotreating in a selective hydrodesulfurization reaction zone using catalyst B under the conditions 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 mass%. Thereafter, carbon deposition cleaning was performed once every month of operation, for 5 days each time, with the weight ratio of recycled oil to fresh oil being 1:1, the hydrogen partial pressure being 10.0 MPa, the reaction temperature being 380°C, and the other conditions being unchanged. After each cleaning, the conditions were restored and operation was continued, and after 14 months of operation (not counting the carbon deposition cleaning time), the desulfurization rate was 93.8% and the difference in hydrogen mass fraction before and after hydrogenation was 0.62 mass%. The specific results are shown in Table 3.

[0044] Comparative Example 1

[0045] The feedstock A was subjected to conventional hydrotreating using catalyst A under the conditions 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 shown in Table 3. Comparison with Example 1 shows that the present application can significantly reduce hydrogen consumption in the hydrodesulfurization process at the same desulfurization rate.

[0046] Comparative Example 2

[0047] The feedstock B was subjected to conventional hydrotreating using catalyst B under the conditions 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 shown in Table 3. Comparison with Example 2 shows that the present application can significantly reduce hydrogen consumption in the hydrodesulfurization process at the same desulfurization rate.

[0048] Comparative Example 3

[0049] The feedstock A was subjected to hydrotreating in a selective hydrodesulfurization reaction zone using catalyst A under the conditions 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%, and after 4 months of operation, 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 shown in Table 3. Comparison with Example 1 shows that carbon deposition cleaning during operation can significantly extend the operation period.

[0050] Table 3

[0051]

[0052] The preferred embodiments of the present application are described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including that each technical feature is combined in any other suitable manner. These simple modifications and combinations should also be considered as disclosed by the present application and fall within the protection scope of the present application.

Claims

1. A method for hydrogenating distillate oil, comprising: Reaction Stage: After the distillate oil is mixed with hydrogen, it enters the fixed-bed selective hydrodesulfurization reaction zone to react with the hydrotreating catalyst. The reaction effluent enters the gas-liquid separation zone for gas-liquid separation. The liquid phase is used as the hydrotreated oil. The reaction conditions in the selective hydrodesulfurization reaction zone are: hydrogen partial pressure 0.1-5.9 MPa, reaction temperature 390-460℃, hydrogen-to-oil volume ratio 800-2500, and volume hourly space velocity 0.1-4.0 h⁻¹. -1 During the reaction stage, the hydrodesulfurization rate is ≥90%, and the hydrogen mass fraction of the hydrogen-generated oil differs from that of the feedstock by ≤0.7% by mass. Online carbon deposit cleaning stage: Distillate oil, circulating oil, and hydrogen are mixed together and then enter the fixed-bed selective hydrodesulfurization reaction zone to contact the hydrotreating catalyst. The reaction effluent enters the gas-liquid separation zone for gas-liquid separation, and at least a portion of the liquid phase is returned to the feed buffer tank as circulating oil. The reaction conditions in the selective hydrodesulfurization reaction zone are: hydrogen partial pressure of 6.0-12.0 MPa, reaction temperature of 350-460℃, hydrogen-to-oil volume ratio of 200-2500, and volume hourly space velocity of 0.1-4.0 h⁻¹. -1 When the hydrodesulfurization rate of the hydrogenated oil is less than 90%, start online carbon deposit cleaning; or, start online carbon deposit cleaning once every 1-6 months.

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

3. 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 hydrogen-generated oil differs from that of the feedstock by ≤0.6% by mass.

4. The method according to claim 1, characterized in that, The online carbon deposit cleaning stage lasts for 1-10 days.

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

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

7. The method according to claim 1, characterized in that, The distillate oil is selected from one or more of catalytic gasoline, catalytic diesel, catalytic slurry, coal tar, coking diesel, and coking wax oil.

8. The method according to claim 1, characterized in that, The hydrogenation catalyst comprises one or more, each independently containing a support and 0-35% by mass of an active metal component.

9. The method according to claim 8, characterized in that, The active metal component is selected from at least one of nickel-tungsten combination, nickel-tungsten-cobalt combination, nickel-molybdenum combination, and cobalt-molybdenum combination.

10. The method according to claim 8, characterized in that, In each of the aforementioned hydrotreating catalysts, the content of the active metal component, calculated as metal oxide, is 0.05-30% by mass.

11. The method according to claim 8, characterized in that, In each of the aforementioned hydrogenation catalysts, the support is independently selected from at least one of alumina, silicon dioxide, and titanium dioxide.

12. The method according to claim 8, characterized in that, The average particle size of each of the aforementioned hydrotreating catalysts is independently 0.5-50 mm, and the bulk density of each of the aforementioned hydrotreating catalysts is independently 0.3-1.2 g / cm³. 3 The average pore size of each of the aforementioned hydrotreating catalysts is independently 6-30 nm, and the specific surface area of ​​each of the aforementioned hydrotreating catalysts is independently 50-400 m². 2 / g.

Images