A method for hydroprocessing of residual oil

Abstract

The application discloses a residual oil hydroprocessing method. In the method, the hydrogenation catalysts include hydrogenation protection catalyst, hydrogenation demetallization catalyst, hydrogenation desulfurization catalyst and hydrogenation de-residue carbon catalyst; in the initial stage of normal production, the hydrogenation desulfurization catalyst and the hydrogenation de-residue carbon catalyst are in the state of incomplete sulfidation, and the hydrogenation protection catalyst and the hydrogenation demetallization catalyst are in the state of complete sulfidation; in the later stage of normal production, the hydrogenation desulfurization catalyst and the hydrogenation de-residue carbon catalyst are supplemented with hydrogen sulfide in the circulating hydrogen. The method can fully utilize the activity of the catalyst and maximize the operation cycle of the catalyst without affecting the normal production, and can also solve the problems of excessive initial reaction activity of each catalyst and excessive hydrogenation reaction performance in the initial operation.

Description

Technical Field

[0001] This invention belongs to the field of residue oil hydrotreating technology, and specifically relates to a method for treating residue oil with hydrogenation. Background Technology

[0002] In recent years, with the increasing deterioration and heavier nature of global crude oil and the increasingly stringent environmental regulations, residue hydrotreating technology has become increasingly important. However, residue oil is characterized by high density and viscosity, and is rich in non-ideal components such as metals, sulfur, nitrogen, and asphaltenes, making its hydrotreating far more difficult than that of other distillate oils. Currently, the main hydrotreating processes for treating inferior and heavy residue oils include fixed-bed, fluidized-bed, slurry-bed, and moving-bed processes, among which the fixed-bed process is the most widely used and the most mature. However, regardless of the process used, the problem of catalyst deactivation due to metal deposition and coking on the catalyst surface is encountered. Therefore, how to extend catalyst life and improve refinery economic efficiency is one of the biggest challenges currently faced.

[0003] Currently, residual oil hydrotreating methods typically employ a graded combination of oxidized hydroprotective catalysts, hydrodemetallization catalysts, hydrodesulfurization catalysts, and hydrodecarbonization catalysts. After thorough sulfidation, the residual oil and other raw materials are then processed, and most methods utilize in-unit wet sulfidation.

[0004] During normal operation of the unit, coke formation and metal deposition are the main causes of gradual deactivation of hydrogenation catalysts. Catalyst deactivation generally progresses through three stages: initial rapid deactivation, intermediate slow deactivation, and final rapid deactivation. In the initial stage, rapid deactivation is caused by a reduction in catalyst surface area and pore blockage due to extensive coke buildup. During this stage, the catalyst often exhibits excessively high hydrogenation activity, resulting in an initial temperature rise and over-performance of the hydrogenation reaction. After initial deactivation, the catalyst enters a slow deactivation state, primarily due to the deposition of metal impurities in the larger pores and bed voids. As metal impurities continue to deposit, catalyst activity gradually decreases, requiring increased temperature to compensate for the activity loss; this stage is generally the longest it can be maintained. With the continuous accumulation of impurities and a gradual increase in temperature, the catalyst eventually enters a rapid deactivation stage with a sharp decline in activity; the final rapid deactivation stage is generally shorter. Furthermore, the main causes of deactivation differ among different types of catalysts. For the protective catalyst and demetallizing catalyst that first come into contact with the residual oil, coking and metal deposition are the main causes of deactivation. For the desulfurization catalyst and residual carbon removal catalyst located later in the graded catalyst system, since most metal impurities are removed from the earlier catalysts, coking is the primary cause of deactivation. The hydrogenation performance and stability of the main catalyst bed are closely related to the long-term operation of the unit. In summary, extending the medium-term slow deactivation period of the catalyst is crucial to maximizing the hydrogenation performance of the main catalyst bed.

[0005] CN1102452C discloses a method for extending catalyst lifespan. This method is used for catalysts in the hydrotreating of heavy and low-quality residue oils. It includes: during the steady-state deactivation period of the residue oil catalyst under normal operation, switching the residue oil feedstock to a distillate oil containing a sulfiding agent into the catalyst bed without interrupting operation, followed by sulfidation, and then switching back to the normal heavy / residue oil feedstock. This method, by switching to a distillate oil containing a sulfiding agent to re-sulfidate the catalyst during normal unit operation, affects the normal production process and is inefficient.

[0006] CN102041045B discloses a start-up method for a residue hydrotreating process. According to the requirements of the residue hydrotreating process, an oxidized residue hydrotreating series of catalysts is selected, including a residue hydrotreating protective catalyst, a residue hydrotreating demetallization catalyst, a residue hydrotreating desulfurization catalyst, and a residue hydrotreating denitrification catalyst. The oxidized residue hydrotreating desulfurization catalyst and / or the oxidized residue hydrotreating denitrification catalyst are treated using an external pre-sulfurization method. The amount of sulfiding agent introduced into the catalysts undergoing external pre-sulfurization is 95%–150% of the theoretical sulfur requirement of all oxidized residue hydrotreating catalysts. After the required catalysts are loaded into the reactor, heated, and activated, the residue feedstock is switched for hydrotreating. This method introduces the required sulfiding agent for all catalysts into the reactor through external pre-sulfurization of the hydrotreating desulfurization catalyst and / or the hydrotreating denitrification catalyst, and then fully sulfides all catalysts through activation during start-up. This method cannot effectively extend the catalyst operating cycle. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a method for hydrotreating residual oil. This method can fully utilize the activity of the catalyst and maximize its operating cycle without affecting normal production. It also solves the problem of excessively high initial reaction activity of catalysts and over-performance of the hydrotreating reaction in the early stages of operation.

[0008] This invention provides a method for hydrotreating residual oil, using hydrotreating catalysts including a hydroprotective catalyst, a hydrodemetallization catalyst, a hydrodesulfurization catalyst, and a hydrocarbon removal catalyst. In the initial stage of normal production, the hydrodesulfurization catalyst and the hydrocarbon removal catalyst are incompletely sulfided, while the hydroprotective catalyst and the hydrodemetallization catalyst are fully sulfided. In the later stages of normal production, hydrogen sulfide from the circulating hydrogen supply is used to supplement the sulfidation of the hydrodesulfurization catalyst and the hydrocarbon removal catalyst.

[0009] In this invention, a hydroprotection catalyst, a hydrodemetallization catalyst, a hydrodesulfurization catalyst, and a hydrodecarbonization catalyst (or hydrodenitrogenation catalyst) are sequentially and progressively packed along the flow direction. The residue hydrotreating method employs at least two reactors, preferably two to four reactors. The hydroprotection catalyst and the hydrodemetallization catalyst are packed in at least one reactor, preferably one to two reactors. The hydrodesulfurization catalyst and the hydrodecarbonization catalyst are packed in at least one reactor, preferably one to two reactors. The reactor containing the hydrodesulfurization catalyst and / or the hydrodecarbonization catalyst is different from the reactor containing the hydroprotection catalyst and / or the hydrodemetallization catalyst. The last reactor containing the hydrodemetallization catalyst is denoted as reactor M; the first reactor containing the hydrodesulfurization catalyst is denoted as reactor S. Reactors M and S are adjacent, and a high-pressure gas-liquid separation system, denoted as H, is added between reactors M and S.

[0010] In the method of this invention, controlling the degree of sulfidation of the hydroprotection catalyst and the hydrodemetallization catalyst to a fully sulfidated state means that, during the conventional sulfidation process, the oxidized active metal supported on the catalyst is completely sulfidated into a sulfidated state, with the degree of sulfidation controlled at 85% or higher, and more preferably 85% to 95%. Controlling the degree of sulfidation of the hydrodesulfurization catalyst and the hydrodecarbonization catalyst to a partially sulfidated state means that, during the conventional sulfidation process, the oxidized active metal supported on the catalyst is partially sulfidated into a sulfidated state, with the degree of sulfidation controlled at 60% to 70%, preferably 60% to 65%.

[0011] In the method of this invention, all catalysts loaded can be in an oxidized state and sulfided by an in-unit pre-sulfidation method. During the in-unit pre-sulfidation process, the hydrogenation protection catalyst and the hydrogenation demetallization catalyst can achieve complete sulfidation using conventional methods. Incomplete sulfidation of the hydrogenation desulfurization catalyst and the hydrogenation residual carbon removal catalyst can be achieved by controlling the sulfidation conditions, such as reducing the sulfidation temperature, reducing the gaseous hydrogen sulfide concentration, and reducing the sulfidation time. The in-unit pre-sulfidation method preferably includes a first-stage sulfidation and a second-stage sulfidation, as detailed below:

[0012] (1) Sulfated oil and hydrogen are in contact with the oxidized catalyst. The temperature of each catalyst bed is controlled at 150-220℃. Then, sulfiding agent is injected into the reaction system and constant temperature sulfidation is carried out at 230-260℃ for 4-12 hours to complete the first stage of sulfidation. The cumulative amount of sulfiding agent injected in this stage is 50%-60% of the theoretical sulfur requirement of all catalysts.

[0013] (2) While introducing sulfurized oil and hydrogen, the sulfurizing agent is continuously injected. The temperature of the hydrogenation protection catalyst and the hydrogenation demetallization catalyst bed is controlled at 290–350°C, and preferably isothermal sulfurization is carried out at 300–320°C for 4–12 hours. The temperature of the hydrogenation desulfurization catalyst and the hydrogenation decarbonization catalyst bed is controlled at 260–280°C, and isothermal sulfurization is carried out at 260–280°C for 4–12 hours, thus completing the second stage of sulfurization. The cumulative injection amount of sulfurizing agent in this stage is 40%–60% of the theoretical sulfur requirement of all catalysts, preferably 40%–50%.

[0014] In the method of the present invention, after step (2) is completed, the device is switched to residual oil and normal production begins. The hydrogenation protection catalyst and the hydrogenation demetallization catalyst are in a fully sulfidated state, and the sulfidation degree of the catalyst can be above 85%, and further can be 85% to 95%. The hydrogenation desulfurization catalyst and the hydrogenation decarbonization catalyst are in a partially sulfidated state, and the sulfidation degree is 60% to 70%, preferably 60% to 65%.

[0015] In the method of this invention, during the initial rapid deactivation stage of normal production (preferably, the operating time is less than 2000 h), all the effluent from reactor M enters the high-pressure gas-liquid separation system H for gas-liquid separation. The circulating hydrogen containing hydrogen sulfide in the gas phase enters the circulating hydrogen desulfurization system. Preferably, the mass content of hydrogen sulfide in the circulating hydrogen is controlled below 0.050 wt%, and more preferably 0.010 wt% to 0.030 wt%. The liquid phase is mixed with the circulating hydrogen after desulfurization and then re-enters reactor S and subsequent reactors to continue the reaction. This can maintain the hydrodesulfurization catalyst and the hydrodecarbonization catalyst in an incompletely sulfided state, while also playing a certain role in sulfur replenishment.

[0016] In the method of this invention, during the later stages of normal production, i.e., the period of slow catalyst deactivation (preferably, the operating time is 2000-8000 hours), sulfidation is performed at least once, preferably 2-4 times, and more preferably 2-3 times, to gradually increase the degree of sulfidation of the hydrodesulfurization catalyst and the hydrodecarbonization catalyst. The total sulfur mass introduced by hydrogen sulfide during the supplementary sulfidation is more than 30% of the theoretical sulfur mass required by the active metals in the hydrodesulfurization catalyst and the hydrodecarbonization catalyst, preferably 30%-55%. When multiple supplementary sulfidations are used, the sulfur mass introduced by hydrogen sulfide in each supplementary sulfidation accounts for more than 20% of the total sulfur mass introduced by hydrogen sulfide in all supplementary sulfidations. Preferably, in two adjacent supplementary sulfidations, the sulfur mass introduced by hydrogen sulfide in the later supplementary sulfidation is at least 25% higher than the sulfur mass introduced by hydrogen sulfide in the previous supplementary sulfidation, preferably at least 30% higher. Preferably, when multiple vulcanization processes are performed, the interval between two adjacent vulcanization processes is 1000 to 3000 hours, and more preferably 1500 to 2000 hours.

[0017] Furthermore, the specific operation process of the supplementary vulcanization is as follows:

[0018] The effluent from reactor M enters the high-pressure gas-liquid separation system H for gas-liquid separation. A portion of the circulating hydrogen containing hydrogen sulfide in the gas phase enters the circulating hydrogen desulfurization system, while the liquid phase, mixed with the remaining circulating hydrogen containing hydrogen sulfide and a portion of the desulfurized circulating hydrogen, re-enters reactor S and subsequent reactors to continue the reaction. This allows for supplementary sulfidation of the hydrodesulfurization catalyst and the hydrocarbon removal catalyst. Each supplementary sulfidation process lasts at least 4 hours, preferably 4-20 hours. After supplementary sulfidation, the liquid phase in the high-pressure gas-liquid separation system H is mixed only with the desulfurized circulating hydrogen before entering reactor S and subsequent reactors for further reaction.

[0019] In the method of the present invention, during the supplemental sulfidation process, the concentration of hydrogen sulfide in the total circulating hydrogen entering reactor S and subsequent reactors (a mixture of circulating hydrogen containing hydrogen sulfide and circulating hydrogen after desulfurization) is controlled to be at least 0.50 wt%, preferably 0.50 wt% to 2.50 wt%.

[0020] In the method of this invention, the hydroprotection catalyst, hydrodemetallization catalyst, hydrodesulfurization catalyst, and hydrodecarbonization catalyst can all be conventional catalysts in the art, and there are no particular limitations in this invention. Generally, the above-mentioned residue hydrotreating catalysts are generally based on porous refractory inorganic oxides such as alumina as supports, with Group VIB and / or Group VIII metal oxides (such as oxides of at least one of W, Mo, Co, Ni, etc.) as active components, and selectively adding various other additives such as P, Si, F, B, etc., as catalysts, for example, the FZC series heavy and residue hydrotreating catalysts developed by Dalian Petrochemical Research Institute.

[0021] In the method of this invention, there are no special requirements for the loading ratio of the hydrogenation protection catalyst, the hydrogenation demetallization catalyst, the hydrogenation desulfurization catalyst, and the hydrogenation decarbonization catalyst. Based on the total volume of all catalysts, the volume ratio of the hydrogenation protection catalyst is generally 5% to 25%, the volume ratio of the hydrogenation demetallization catalyst is 10% to 40%, the volume ratio of the hydrogenation desulfurization catalyst is 15% to 50%, and the volume ratio of the hydrogenation decarbonization catalyst is 20% to 40%.

[0022] In the method of the present invention, the residue oil may include at least one of atmospheric residue oil and vacuum residue oil, and may also include at least one of wax oil (such as atmospheric wax oil, vacuum wax oil, coking wax oil, catalytic wax oil), deasphalted oil, and BTX, and may also include at least one of various oils obtained from coal, petroleum sands, oil shale and asphalt, synthetic oil from the Fischer-Tropsch process, and oil derived from recycled waste oil and polymers.

[0023] In the method of this invention, the normal operating conditions for fixed-bed hydrotreating of residual oil are: reaction temperature 300–440℃, preferably 340–425℃, more preferably 360–415℃; reaction pressure 10–18 MPa, preferably 13–16 MPa; hydrogen-to-oil volume ratio 500–2000, preferably 700–1500; and liquid hourly space velocity 0.1–1.0 h⁻¹. -1 Preferably, it is 0.2 to 0.4 h. -1 .

[0024] Compared with the prior art, the method of the present invention has the following advantages:

[0025] (1) The method of this invention controls the hydrogenation protection catalyst and the hydrogenation demetallization catalyst to achieve a fully sulfidated state, while the hydrogenation desulfurization catalyst and the hydrogenation decarbonization catalyst achieve an incompletely sulfidated state. During the slow deactivation period of the catalyst in normal production, hydrogen sulfide from recycled hydrogen is used as a sulfiding agent to supplement the sulfidation of the hydrogenation desulfurization catalyst and the hydrogenation decarbonization catalyst, so that the hydrogenation activity is released slowly and fully. This allows for full utilization of the catalyst activity and maximizes the extension of the catalyst's operating cycle. It also solves the problem of excessively high initial reaction activity and excessive hydrogenation reaction performance of the catalyst in the initial stage of operation.

[0026] (2) The method of this invention optimizes the process flow by setting up a high-pressure gas-liquid separation system H between reactor M and reactor S. This ensures that the hydrodesulfurization catalyst and the hydrodecarbonization catalyst remain in an incompletely sulfided state during the initial stage of normal production after sulfidation. Furthermore, when supplemental sulfidation is needed, it can be completed during normal production without affecting the normal operation of the unit. In addition, since the liquid phase after gas-liquid separation mixes with the recycled hydrogen after hydrogen sulfide removal and continues to react in reactor S during normal production, a high hydrogen partial pressure can be maintained in the subsequent reactors, which also delays the catalyst deactivation process due to carbon deposition. This method is most advantageous in achieving ultra-long operating cycles when processing heavy residue oil feedstock with low nickel and vanadium content, where the impact of metal deposition deactivation on the service life of the upstream protective catalyst and the demetallization catalyst is reduced. Attached Figure Description

[0027] Figure 1 This is a schematic flowchart of the method of the present invention;

[0028] The reference numerals in the attached figures are explained as follows:

[0029] 15-Residue oil feedstock; 1-First reactor; 2-Second reactor (M); 3-Third reactor (S); 4-Fourth reactor; 5-High-pressure gas-liquid separation system H; 6-Liquid phase; 7-First sulfur-containing gas phase; 8-Circulating hydrogen desulfurization system; 9-First desulfurized gas phase; 10-Separation and fractionation system; 11-Second sulfur-containing gas phase; 12-Second desulfurized gas phase; 13-Hydrogenated liquid phase product; 14-Third sulfur-containing gas phase. Detailed Implementation

[0030] The method of the present invention will be described in detail below with reference to the embodiments, but the following embodiments do not limit the above invention.

[0031] In this invention, the degree of sulfidation of the catalyst can be characterized and measured using X-ray photoelectron spectroscopy (XPS), a technique well known to those skilled in the art.

[0032] This invention provides a method for hydrotreating residual oil, the schematic flowchart of which is shown below. Figure 1 The process includes: raw residue 15 is mixed with hydrogen (second desulfurized gas phase 12 and supplementary hydrogen) and fed into reactor 1 for hydrogenation; the product of reactor 1 is fed into reactor 2 (M) for hydrogenation; the product of reactor 2 is fed into high-pressure gas-liquid separation system H5; the resulting liquid phase 6 is mixed with first desulfurized gas phase 9 and fed into reactor 3 (S) for hydrogenation; the product of reactor 3 is fed into reactor 4 for hydrogenation; the resulting product is fed into separation and fractionation system 10 for separation; the second sulfur-containing gas phase 11 obtained from the top is fed into circulating hydrogen desulfurization system 8 for desulfurization treatment; and the separation and fractionation system 10 yields hydrogenated liquid phase product 13. Specifically, the gas phase obtained from high-pressure gas-liquid separation system H5, i.e., the first sulfur-containing gas phase 7, is fed into circulating hydrogen desulfurization system 8 for desulfurization treatment; the first desulfurized gas phase 9 after desulfurization treatment can be used as hydrogen feed for reactor 3; and the second desulfurized gas phase 12 after desulfurization treatment can be used as hydrogen feed for reactor 1. When additional sulfidation is required, a portion of the gas phase obtained from the high-pressure gas-liquid separation system H5, i.e., the first sulfur-containing gas phase 7, enters the circulating hydrogen desulfurization system 8 for desulfurization treatment. The remaining portion, i.e., the third sulfur-containing gas phase 14, is mixed with the liquid phase 6 obtained from the high-pressure gas-liquid separation system H5 and the first desulfurized gas phase 9 after desulfurization and enters the third reaction system.

[0033] Example 1

[0034] Sulfidation process tests were conducted on three identical pilot-scale units, A, B, and C, using the FZC series residue hydrotreating catalyst developed by the Dalian Research Institute of Petroleum and Chemical Industry of Sinopec. The start-up medium oil, sulfidizing agent, residue feedstock, operating conditions, catalyst, and its loading scheme were all identical for units A, B, and C. Four identical reactors were used, with the following catalyst loading configurations: Reactor 1 was loaded from top to bottom with FZC-100B, FZC-12B, FZC-103D, and FZC-103E (all reactors in Reactor 1 were hydrogenation protection catalysts), with a loading volume ratio of 2.6:1.6:3.4:15.4; Reactor 2 was loaded from top to bottom with FZC-28A and FZC-204A (Reactor 2 was reactor M, both reactors in Reactor 2 were hydrogenation demetallization catalysts), with a loading volume ratio of 11.8:20.4; Reactor 3 was loaded from top to bottom with FZC-33BT (Reactor 2 was reactor S, both reactors in Reactor 3 were hydrogenation desulfurization catalysts); and Reactor 4 was loaded from top to bottom with FZC-41BT (all reactors in Reactor 4 were hydrogenation decarbonization catalysts), with a loading volume ratio of 23.0:32.2:19.2:25.6 for the four reactors, and the total catalyst loading volume was 850 mL. The main sulfidation conditions of the unit are: reaction pressure 17.0 MPa, hydrogen-to-oil volume ratio 600 (inlet gas flow rate 102 L / h, the same below), and liquid hourly space velocity 0.20 h⁻¹. -1 (The feed rate of the unit is 166 g / h, the same below). Carbon disulfide is used as the sulfiding agent. The main properties of the sulfiding medium oil are shown in Table 1. Based on the amount of active metal loaded on all catalysts, the theoretical sulfur requirement of the catalyst is calculated to be 27 grams, and the corresponding theoretical carbon disulfide requirement is 32 grams.

[0035] The catalyst sulfidation process in each reactor of Unit A is as follows.

[0036] (1) When the temperature of each anticatalyst bed is 150°C, while continuing to introduce hydrogen, sulfidation medium oil (properties shown in Table 1) is introduced into the reaction system; the temperature of each anticatalyst bed continues to rise to 175°C at a rate not exceeding 10°C / h, and then carbon disulfide is injected into the feedstock system.

[0037] (2) The temperature of each reaction catalyst bed continues to rise to 260°C at a rate not exceeding 10°C / h, and is kept at a constant temperature for 12 hours to complete the first stage of sulfidation. During this stage, a total of 18g of carbon disulfide is injected.

[0038] (3) While introducing sulfiding medium oil and hydrogen, the sulfiding agent is continuously injected. The temperature of the first and second reactor beds is gradually increased to 320°C at a rate not exceeding 10°C / h, and then kept at a constant temperature for 12 hours. The temperature of the third and fourth reactor beds is increased to 280°C at a rate not exceeding 10°C / h, and then kept at a constant temperature for 12 hours. The first and second reactor beds, as well as the third and fourth reactor beds, complete the second stage of sulfidation. A total of 18g of carbon disulfide is injected during this stage.

[0039] At this point, the staged sulfidation process in each reactor of Unit A was completed. The catalysts from reactors one, two, three, and four were then unloaded and stored in cyclohexane. The degree of catalyst sulfidation in different reactors was characterized and measured using X-ray photoelectron spectroscopy (XPS), and the results are shown in Table 2.

[0040] Table 1. Main properties of the experimental sulfurizing medium oil and residual oil feedstock

[0041] project Sulfated medium oil Residue oil feedstock <![CDATA[Density (20 °C), kg / m 3 > 895 976 <![CDATA[Kinematic viscosity (50 °C), mm 2 / s]]> 11 — <![CDATA[Kinematic viscosity (100 °C), mm 2 / s]]> — 68.3 Sulfur, wt% 2.30 3.51 Nitrogen, wt% 430 3196 Residual carbon, wt% — 10.7 Metal (nickel + vanadium), μg / g <0.10 78.9 Initial boiling point, ℃ 219 238 10％，℃ 302 366 30％，℃ 353 467 50％，℃ 388 549 70％，℃ 419 634 90％，℃ 456 740 Final boiling point, ℃ 482 750

[0042] Table 2. Degree of sulfidation of catalysts in different sulfidation processes

[0043] project Set A Set B FZC-103E, % 85.3 85.1 FZC-28A, % 86.4 85.8 FZC-204A, % 85.2 86.7 FZC-33BT, % 63.2 86.5 FZC-41BT, % 64.7 85.4

[0044] Example 2

[0045] The sulfidation process and subsequent life evaluation tests continued on the pilot plant (Unit A). The catalyst loading and sulfidation process were exactly the same as in Example 1.

[0046] After completing the sulfidation process in Example 1, the process gradually transitions to the normal operation stage of the residual oil feedstock.

[0047] Under normal operating conditions, the standard operating conditions are: reaction pressure 17.0 MPa, hydrogen-to-oil ratio 600 (v / v), and liquid hourly space velocity 0.20 h⁻¹. -1 The reaction temperature is 380℃, and the properties of the residue feedstock are shown in Table 1. During normal operation of Unit A, the effluent from the second reactor outlet undergoes gas-liquid separation. The liquid phase is then mixed with hydrogen gas (0.050 wt% hydrogen sulfide concentration) at the inlet of the third reactor and continues to enter subsequent reactors. This is the normal operating state. After stable operation for 2000 hours under the above conditions, and obtaining impurity removal data for the hydrotreated product oil under standard operating conditions, the liquid phase from the second reactor outlet and a mixed hydrogen mixture (1.0 wt% hydrogen sulfide concentration at the inlet of the third reactor, where the third sulfur-containing gas phase from the third reactor outlet is mixed with the first desulfurized gas phase from the circulating hydrogen desulfurization system, with a mixed gas flow rate still 102 L / h) enter the third and fourth reactors. Under standard operating conditions, the third and fourth reactors are subjected to isothermal sulfurization for 1.5 hours (the total sulfur mass introduced by hydrogen sulfide is 11.67% of the total theoretical sulfur required by the active metals in the hydrodesulfurization catalyst and the hydrodecarbonization catalyst). Then, the system was restored to normal operation and the hydrogenated oil was analyzed under standard operating conditions. The test results of the three-stage and four-stage catalysts before and after resulfurization are shown in Table 3.

[0048] Table 3 Experimental process conditions and results

[0049]

[0050]

[0051] Example 3

[0052] After the test conditions in Example 2 were completed, and the hydrogenated oil was operated stably for 4000 hours under normal operating conditions, the impurity removal data of the hydrotreated product oil was obtained under standard operating conditions. The liquid phase from the outlet of the second reactor was mixed with hydrogen gas at a hydrogen sulfide concentration of 1.5 wt% at the inlet of the third reactor and then fed into the third and fourth reactors. The third and fourth reactors were subjected to isothermal sulfidation for 1.5 hours under standard operating conditions (the total sulfur mass introduced by hydrogen sulfide was 17.50% of the total theoretical sulfur mass required by the active metals in the hydrodesulfurization catalyst and the hydrodecarbonization catalyst). Then, the operation was restored to normal operating conditions, and the hydrotreated product oil was analyzed under standard operating conditions. The test results of the third and fourth reactor catalysts before and after re-sulfidation are shown in Table 4.

[0053] Table 4. Experimental process conditions and results

[0054]

[0055] Example 4

[0056] After the test conditions in Example 3 were completed, and the hydrogenated oil was operated stably for 6000 hours under normal operating conditions, the impurity removal data of the hydrotreated product oil was obtained under standard operating conditions. The liquid phase from the outlet of the second reactor was mixed with hydrogen gas at a hydrogen sulfide concentration of 1.5 wt% at the inlet of the third reactor and then fed into the third and fourth reactors. The third and fourth reactors were subjected to isothermal sulfidation for 2 hours under standard operating conditions (the total sulfur mass introduced by hydrogen sulfide was 23.34% of the total theoretical sulfur mass required by the active metals in the hydrodesulfurization catalyst and the hydrodecarbonization catalyst). Then, the operation was restored to normal operating conditions, and the hydrotreated product oil was analyzed under standard operating conditions. The test results of the third and fourth reactor catalysts before and after re-sulfidation are shown in Table 5.

[0057] Table 5. Experimental process conditions and results

[0058]

[0059] Comparative Example 1

[0060] The catalyst loading and implementation process of Unit B before sulfidation is exactly the same as that of Unit A. The specific implementation process of staged sulfidation of catalysts in each reactor of Unit B is as follows:

[0061] (1) When the temperature of each anti-catalyst bed is 150°C, sulfurized medium oil is introduced into the reaction system; the temperature of each anti-catalyst bed continues to rise to 175°C at a rate not exceeding 10°C / h, and then carbon disulfide is injected into the feedstock system.

[0062] (2) The temperature of each reaction catalyst bed continues to rise to 260°C at a rate not exceeding 10°C / h, and is kept at a constant temperature for 12 hours to complete the first stage of sulfidation. During this stage, a total of 18g of carbon disulfide is injected.

[0063] (3) While introducing sulfiding medium oil and hydrogen, continue to inject sulfiding agent. The bed temperature of the first and second reactors is gradually increased to 320°C at a rate not exceeding 10°C / h, and constant temperature sulfidation is carried out for 12 hours. Similarly, the third and fourth reactors are heated to 320°C at a rate not exceeding 10°C / h, and constant temperature sulfidation is carried out for 12 hours. Each reactor completes the second stage of sulfidation, during which a total of 18g of carbon disulfide is injected.

[0064] At this point, the staged sulfidation process in each reactor of Unit B was completed. The catalysts from reactors one, two, three, and four were then unloaded and stored in cyclohexane. The degree of catalyst sulfidation in different reactors was characterized and measured using X-ray photoelectron spectroscopy (XPS), and the results are shown in Table 2.

[0065] Comparative Example 2

[0066] The sulfidation process and subsequent life evaluation tests continued on the pilot unit B. The catalyst loading and sulfidation process on the pilot unit B were exactly the same as in Comparative Example 1.

[0067] After completing the sulfidation process in Comparative Example 1, the process gradually transitions to the normal operation stage of the residual oil feedstock.

[0068] The operating conditions of Unit B during normal operation are the same as those of Unit A. After 2000 hours of operation, the three-stage and four-stage catalysts were re-sulfurized according to the sulfidation conditions of Unit A in Example 2. The test results are shown in Table 3.

[0069] Comparative Example 3

[0070] After the B unit was tested under the conditions of Comparative Example 2, and after 4000 hours of normal operation, the three-trans and four-trans catalysts were re-sulfurized according to the sulfidation conditions of the A unit in Example 3. The test results are shown in Table 4.

[0071] Comparative Example 4

[0072] After the B unit was tested under the conditions of Comparative Example 3, and after 6000 hours of normal operation, the three-trans and four-trans catalysts were re-sulfurized according to the sulfidation conditions of the A unit in Example 4. The test results are shown in Table 5.

[0073] Example 5

[0074] The catalyst loading and sulfidation method for Unit C is the same as that for Unit A in Example 1.

[0075] After the sulfidation process is completed, the process gradually transitions to the normal operation stage of the residual oil feedstock.

[0076] Under normal operating conditions, the standard operating conditions are: reaction pressure 17.0 MPa, hydrogen-to-oil ratio 600 (v / v), and liquid hourly space velocity 0.20 h⁻¹. -1The reaction temperature was 380℃, and the properties of the residue feedstock are shown in Table 1. During normal operation of Unit A, the effluent from the second reactor outlet undergoes gas-liquid separation. The liquid phase is then mixed with hydrogen gas (0.050 wt% hydrogen sulfide concentration) at the inlet of the third reactor and continues to enter subsequent reactors. This is the normal operating state. After stable operation for 2000 hours under the above conditions, and obtaining impurity removal data for the hydrotreated product oil under standard operating conditions, the liquid phase from the second reactor outlet is mixed with hydrogen gas (1.0 wt% hydrogen sulfide concentration) at the inlet of the third reactor and enters the third and fourth reactors. Under standard operating conditions, the third and fourth reactors are subjected to isothermal sulfidation for 0.9 hours (the total sulfur mass introduced by hydrogen sulfide is 7.00% of the theoretical sulfur mass required by the active metals in the hydrodesulfurization catalyst and the hydrodecarbonization catalyst). Then, the system is restored to normal operating conditions, and the hydrotreated product oil is analyzed under standard operating conditions. The test results of the third and fourth reactor catalysts before and after re-sulfidation are shown in Table 3.

[0077] After 4000 hours of stable operation under normal conditions, and obtaining impurity removal data for the hydrotreated product oil under standard operating conditions, the liquid phase from the outlet of the second reactor was mixed with hydrogen gas at the inlet of the third reactor (hydrogen sulfide concentration of 1.5 wt%) and then fed into the third and fourth reactors. Under standard operating conditions, the third and fourth reactors were subjected to isothermal sulfidation for 2.0 hours (the total sulfur mass introduced by hydrogen sulfide was 23.34% of the theoretical sulfur mass required by the active metals in the hydrodesulfurization catalyst and the hydrodecarbonization catalyst). Then, the operation was restored to normal conditions, and the hydrotreated product oil was analyzed under standard operating conditions. The test results of the third and fourth reactor catalysts before and after re-sulfidation are shown in Table 4.

[0078] After 6000 hours of stable operation under normal conditions, and obtaining impurity removal data for the hydrotreated product oil under standard operating conditions, the liquid phase from the outlet of the second reactor was mixed with hydrogen gas at a hydrogen sulfide concentration of 1.5 wt% at the inlet of the third reactor and then fed into the third and fourth reactors. Under standard operating conditions, the third and fourth reactors were subjected to isothermal sulfidation for 1.9 hours (the total sulfur mass introduced by hydrogen sulfide was 22.17% of the theoretical sulfur mass required by the active metals in the hydrodesulfurization catalyst and the hydrodecarbonization catalyst). Then, the operation was restored to normal conditions, and the hydrotreated product oil was analyzed under standard operating conditions. The test results of the third and fourth reactor catalysts before and after re-sulfidation are shown in Table 5.

[0079] During plant operation, when using the same residual oil feedstock, under constant reaction pressure, space velocity, hydrogen-to-oil ratio, and reaction temperature, the impurity removal rate of the hydrotreated oil gradually decreases with prolonged operation. To ensure the hydrotreated oil meets downstream feed requirements, the reaction temperature must be increased to compensate for catalyst activity loss; however, increased temperature inevitably accelerates catalyst deactivation. The method of this invention can slowly release the catalyst's hydrogenation activity, improving the impurity removal rate of the hydrotreated oil, and correspondingly, slowing down the catalyst's heating rate, thereby extending the catalyst's lifespan.

Claims

1. A method for hydroprocessing of residual oil, wherein, The hydrogenation catalysts used include hydrogenation guard catalysts, hydrogenation demetallization catalysts, hydrogenation desulfurization catalysts and hydrogenation de-residue carbon catalysts; in the method, at the beginning of normal production, the hydrogenation desulfurization catalysts and the hydrogenation de-residue carbon catalysts are in an incomplete sulfidation state, and the hydrogenation guard catalysts and the hydrogenation demetallization catalysts are in a complete sulfidation state; in the later stage of normal production, the hydrogenation desulfurization catalysts and the hydrogenation de-residue carbon catalysts are supplemented with sulfidation by using hydrogen sulfide in the circulating hydrogen; the hydrogenation guard catalysts, the hydrogenation demetallization catalysts, the hydrogenation desulfurization catalysts and the hydrogenation de-residue carbon catalysts are sequentially and proportionally loaded along the flow direction; the sulfidation degree of the hydrogenation guard catalysts and the hydrogenation demetallization catalysts is controlled to be in a complete sulfidation state, and the sulfidation degree is controlled to be above 85%; the sulfidation degree of the hydrogenation desulfurization catalysts and the hydrogenation de-residue carbon catalysts is controlled to be in an incomplete sulfidation state, and the sulfidation degree is controlled to be between 60% and 70%.

2. The method of claim 1, wherein, The residue oil hydroprocessing method uses at least two reactors, wherein the hydrogenation guard catalysts and the hydrogenation demetallization catalysts are loaded in at least one reactor, and the hydrogenation desulfurization catalysts and the hydrogenation de-residue carbon catalysts are loaded in at least one reactor.

3. The method of claim 2, wherein, The residue oil hydroprocessing method uses 2 to 4 reactors, wherein the hydrogenation guard catalysts and the hydrogenation demetallization catalysts are loaded in 1 to 2 reactors, and the hydrogenation desulfurization catalysts and the hydrogenation de-residue carbon catalysts are loaded in 1 to 2 reactors.

4. The method according to claim 1 or 2, characterized in that, The reactor in which the hydrogenation desulfurization catalyst and / or the hydrogenation de-residue carbon catalyst is located is different from the reactor in which the hydrogenation guard catalyst and / or the hydrogenation demetallization catalyst is located, wherein the last reactor loaded with the hydrogenation demetallization catalyst is denoted as reactor M; the first reactor loaded with the hydrogenation desulfurization catalyst is denoted as reactor S; wherein the reactor M and the reactor S are adjacent, a high-pressure gas-liquid separation system is additionally arranged between the reactor M and the reactor S, and is denoted as H.

5. The method according to claim 1 or 2, characterized in that, The sulfidation degree of the hydrogenation guard catalysts and the hydrogenation demetallization catalysts is controlled to be in a complete sulfidation state, and the sulfidation degree is controlled to be between 85% and 95%; and / or, the sulfidation degree of the hydrogenation desulfurization catalysts and the hydrogenation de-residue carbon catalysts is controlled to be in an incomplete sulfidation state, and the sulfidation degree is controlled to be between 60% and 65%.

6. The method of claim 1, wherein, Each of the loaded catalysts is an oxidized state catalyst, and is sulfidized by an in-situ sulfidation method.

7. The method of claim 6, wherein, The in-situ sulfidation method includes a first stage sulfidation and a second stage sulfidation, and is specifically as follows: (1) Sulfurized oil and hydrogen are contacted with the oxidized state catalysts, the temperature of each catalyst bed is controlled to be between 150 and 220℃, then a sulfidation agent is injected into the reaction system, and the first stage sulfidation is completed by constant temperature sulfidation at a temperature of 230 to 260℃ for 4 to 12 hours; the cumulative injection amount of the sulfidation agent in this stage is 50% to 60% of the theoretical sulfur requirement of all the catalysts; (2) continue to inject the sulfiding agent under the condition of passing in the sulfided oil and hydrogen, wherein the bed temperature of the hydrogen protection catalyst and the hydrogen demetallization catalyst is controlled at 290-350 DEG C, and the bed temperature of the hydrogen desulfurization catalyst and the hydrogen residual carbon removal catalyst is controlled at 260-280 DEG C, and the sulfiding is carried out at a constant temperature of 300-320 DEG C for 4-12 hours and at a constant temperature of 260-280 DEG C for 4-12 hours respectively to complete the second stage of sulfiding; the cumulative injection amount of the sulfiding agent in this stage is 40%-60% of the theoretical required sulfur amount of all the catalysts.

8. The method of claim 7, wherein, In step (2), the cumulative injection amount of the sulfiding agent in the second stage of sulfiding is 40%-50% of the theoretical required sulfur amount of all the catalysts.

9. The method of claim 4, wherein, In the initial stage of normal production, i.e. the initial rapid deactivation stage, the reactor M reaction effluent is all introduced into the high-pressure gas-liquid separation system H for gas-liquid separation, wherein the circulating hydrogen containing hydrogen sulfide in the gas phase is all introduced into the circulating hydrogen desulfurization system to control the mass content of hydrogen sulfide in the circulating hydrogen to be below 0.050wt%; The liquid phase is mixed with the circulating hydrogen after desulfurization of hydrogen sulfide and then introduced into the reactor S and the subsequent reactors for continuous reaction to maintain the hydrogen desulfurization catalyst and the hydrogen residual carbon removal catalyst in an incomplete sulfided state.

10. The method of claim 9, wherein, The initial stage of normal production refers to the period of less than 2000 hours of operation time.

11. The method of claim 9, wherein, The mass content of hydrogen sulfide in the circulating hydrogen is controlled to be 0.010-0.030wt%.

12. The method of claim 4 or 9, wherein, The supplemental sulfiding is carried out at least once during the middle-late stage of normal production, i.e. the period of slow catalyst deactivation.

13. The method of claim 12, wherein, The middle-late stage of normal production refers to the period of 2000-8000 hours of operation time.

14. The method of claim 12, wherein, The supplemental sulfiding is carried out 2-4 times during the middle-late stage of normal production, i.e. the period of slow catalyst deactivation.

15. The method of claim 1, wherein, The total sulfur mass introduced by hydrogen sulfide in the supplemental sulfiding is more than 30% of the total theoretical required sulfur mass of the active metals in the hydrogen desulfurization catalyst and the hydrogen residual carbon removal catalyst; when multiple supplemental sulfidings are adopted, the sulfur mass introduced by hydrogen sulfide in each supplemental sulfiding is more than 20% of the total sulfur mass introduced by hydrogen sulfide in all the supplemental sulfidings.

16. The method of claim 15, wherein, The total sulfur mass introduced by hydrogen sulfide in the supplemental sulfiding is 30%-55% of the total theoretical required sulfur mass of the active metals in the hydrogen desulfurization catalyst and the hydrogen residual carbon removal catalyst.

17. The method of claim 15, wherein, When multiple supplemental sulfidings are adopted, the sulfur mass introduced by hydrogen sulfide in the later supplemental sulfiding is at least 25% higher than that in the former supplemental sulfiding.

18. The method of claim 17, wherein, When multiple supplemental sulfidings are adopted, the sulfur mass introduced by hydrogen sulfide in the later supplemental sulfiding is at least 30% higher than that in the former supplemental sulfiding.

19. The method of claim 12, wherein, When multiple supplemental sulfidings are adopted, the interval time between the adjacent two supplemental sulfidings is 1000-3000 hours.

20. The method of claim 19, wherein, When multiple supplemental sulfidings are adopted, the interval time between the adjacent two supplemental sulfidings is 1500-2000 hours.

21. The method of claim 1, wherein, The specific operation process of the supplemental sulfiding is as follows: The reactor M reaction effluent all enters a high-pressure gas-liquid separation system H for gas-liquid separation, wherein a part of the circulating hydrogen containing hydrogen sulfide in the gas phase enters a circulating hydrogen desulfurization system, and the liquid phase is mixed with another remaining part of the circulating hydrogen containing hydrogen sulfide and a part of the circulating hydrogen after desulfurization to enter the reactor S and subsequent reactors again to continue the reaction, so that the hydrogen desulfurization catalyst and the hydrogen residual carbon removal catalyst are supplemented with sulfidation, and the sulfidation time is at least 4 hours each time; after the completion of the sulfidation, the liquid phase in the high-pressure gas-liquid separation system H is mixed with the circulating hydrogen after desulfurization to enter the reactor S and subsequent reactors again to continue the reaction.

22. The method of claim 21, wherein, During the supplement sulfidation process, the concentration of hydrogen sulfide in the total circulating hydrogen entering the reactor S and subsequent reactors is controlled to be at least 0.50 wt%.

23. The method of claim 22, wherein, During the supplement sulfidation process, the concentration of hydrogen sulfide in the total circulating hydrogen entering the reactor S and subsequent reactors is controlled to be 0.50 wt% to 2.50 wt%.

24. The method of claim 1, wherein, The residue includes at least one of atmospheric residue and vacuum residue.

25. The method of claim 1, wherein, The normal operating conditions of the fixed bed of residual oil hydrogenation are: reaction temperature 300-440℃, reaction pressure 10-18 MPa, hydrogen oil volume ratio 500-2000, liquid hourly space velocity 0.1-1.0h -1 .

26. The method of claim 1, wherein, The normal operating conditions of the fixed bed of residual oil hydrogenation are: reaction temperature 340~425℃, reaction pressure 13~16 MPa, hydrogen oil volume ratio 700~1500, liquid hourly space velocity 0.2~0.4h -1 .

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