JP6420961B2 - Recycling method of heavy oil desulfurization catalyst - Google Patents

Description

  The present invention relates to a method for recycling a heavy oil desulfurization catalyst used for hydrodesulfurization treatment of heavy oil.

  Petroleum refining has many processes for refining various fractions by hydrodesulfurization, and various catalysts have been developed. Such catalysts include desulfurization and denitrification catalysts such as naphtha, kerosene and light oil, desulfurization and denitrification catalysts for heavy gas oil, and desulfurization and denitrification catalysts such as residual oil and heavy oil. Among them, the catalyst used when hydrodesulfurizing naphtha, kerosene, light oil and the like having a relatively low boiling point and almost no metal impurities such as vanadium has a low degree of deterioration due to use.

  The catalyst used when hydrodesulfurizing naphtha, kerosene, light oil and the like is not deteriorated by metal impurities such as vanadium, and the deterioration of the catalyst is due to the accumulation of a small amount of carbonaceous matter. Therefore, if carbon was removed from the catalyst by combustion, the catalyst could be reused. Furthermore, regarding the removal of carbonaceous matter, since the amount of carbonaceous matter on the catalyst was small, the catalyst could be regenerated without requiring strict combustion control. Some of the catalysts used have a low degree of deterioration, and such catalysts can be reused as they are without being regenerated.

  Recently, hydrodesulfurization treatment catalysts such as heavy gas oil and vacuum gas oil have also been regenerated and reused, and a regeneration method and a reuse method of the catalyst have been established. For example, the hydrocracking catalyst used in the heavy gas oil hydrocracking process and the hydrodenitrogenation catalyst used for its pretreatment are regenerated and reused by hydrogen activation or oxygen activation. Since the catalyst used in the hydrodesulfurization treatment of these distillate oils is used as a raw material oil with few metal impurities, there is little deposition on the catalyst of metals such as vanadium. In addition, the amount of carbon deposited on the catalyst is small, and the carbon deposited on the catalyst tends to burn. For this reason, since the catalyst surface does not become so high during regeneration by combustion, the change in the pore structure of the catalyst and the supported state of the active metal by the regeneration process is small, and it is again used for the treatment of distillate oil such as heavy gas oil and vacuum gas oil. It was able to be used (refer nonpatent literature 1).

  However, heavy oil containing a fraction having a higher boiling point or a fraction that cannot be distilled contains a large amount of carbonaceous components such as asphaltenes and metal impurities, and a large amount of the catalyst on the spent catalyst after being used for hydrodesulfurization treatment. Carbonaceous and metallic components are deposited. The carbonaceous matter must be removed at a high combustion temperature because the carbonaceous matter cannot be easily removed from the spent catalyst in which the carbonaceous matter and the metal content are simultaneously accumulated. For this reason, the change in the pore structure of the catalyst and the supported state of the active metal due to the regeneration treatment became large, and the function of the catalyst after removing the carbonaceous matter was remarkably lowered (see Non-Patent Document 2 and Non-Patent Document 3). For this reason, the catalyst used for the hydrodesulfurization treatment of heavy oil has been disposed of without being reused.

However, it is very important to regenerate and reuse the catalyst used in the hydrodesulfurization treatment of heavy oil in order to reduce waste and catalyst costs. As a method for reusing a regenerated catalyst, for example, a method for regenerating a heavy oil hydrotreating catalyst described in Patent Document 1 and a method for hydrodesulfurizing a heavy oil described in Patent Document 2 are known. According to the method for regenerating a heavy oil hydrotreating catalyst described in Patent Document 1, a catalyst deactivated by use in a heavy oil hydrodesulfurization process is regenerated, and its pore volume, pore diameter, vanadium A regenerated hydrotreating catalyst having a specific metal allowance calculated from the amount deposited and the outer surface area per volume can be used again for the hydrotreating of heavy oil. In addition, according to the hydrodesulfurization method for heavy oil described in Patent Document 2, a catalyst that has been deactivated by use in a hydroprocessing process such as heavy oil and has not been used is regenerated and effectively used. be able to.

Japanese Patent No. 3708811 Japanese Patent No. 3527635

Studies in Surface and Catalysis vol. 88 P199 (1994) Catal. Today vol. 17 No. 4 P539 (1993) Catal. Rev. Sci. Eng. 33 (3 & 4) P281 (1991)

  However, in the method for regenerating a heavy oil hydrotreating catalyst described in Patent Document 1, the physical properties of the used catalyst that is the raw material for the regenerated catalyst depend on the raw material and the operating conditions, and this greatly affects the reproducibility. For this reason, in a device having a high driving severity, it cannot always be used as a regenerated catalyst. Moreover, the hydrodesulfurization method of heavy oil described in Patent Document 2 only proposes a one-time one-time regeneration method, and is not a continuous and stable regeneration method. Accordingly, an object of the present invention is to provide a method for recycling a heavy oil desulfurization catalyst that can more effectively reuse a used catalyst.

As a result of intensive studies, the present inventors have determined that the catalyst that has been deactivated by heavy oil hydrodesulfurization treatment and cannot be regenerated conventionally is located at a predetermined stage from the top of the reaction tower. The present inventors have found that the catalyst can be used and completed the present invention. That is, the present invention is as follows.
[1] In one apparatus, a catalyst for use in a hydrodesulfurization apparatus in which raw material heavy oil is introduced from the top side of a reaction tower packed with a catalyst and hydrodesulfurized raw material heavy oil is discharged from the bottom side of the reaction tower. A recycling method in which a heavy oil desulfurization catalyst charged in a reaction tower is divided into two or more stages, and an m-th stage (m is an integer of 2 or more) heavy oil desulfurization catalyst from the top of the reaction tower; Extracting a heavy oil desulfurization catalyst in the n-th stage (n is an integer satisfying n <m) from the top of the reaction tower; and a heavy oil desulfurization catalyst extracted from the m-th stage from the top of the reaction tower. A regenerated step, a catalyst or a new catalyst which is filled with a heavy oil desulfurization catalyst regenerated at the nth stage from the top of the reaction tower and is regenerated by being extracted from a stage farther from the top of the reaction tower than at the mth stage And a step of charging the heavy oil desulfurization catalyst, comprising the step of:
[2] When the heavy oil desulfurization catalyst charged in the m-th stage is regenerated and used in the n-th stage, the allowable metal amount MPr represented by the following formula (1) is n + 1-th stage (where n + 1 <m) The method for recycling the heavy oil desulfurization catalyst according to the above [1], which is larger than the allowable metal amount MPr when the catalyst charged in the catalyst is regenerated and used in the same n + 1 stage.
MPr = (PV / 2Vv) × {8 × 10 ⁵ × (PD) ^1.3 } × (Sp / Vp) − (VA1 + VA2) (1)
In the formula (1), each symbol represents the following.
PV: Pore volume at the time of new catalyst (m ³ / kg)
Vv: Volume when vanadium is deposited by 1 wt% on a new catalyst of 1 kg = volume when considered as vanadium sulfide = 3.8 × 10 ⁻⁶ (m ³ /% kg)
PD: average pore diameter (m) for new catalyst
Sp: average outer surface area of one grain at the time of new catalyst (m ² )
Vp: average volume of one grain at the time of new catalyst (m ³ )
VA1: Vanadium deposition amount (% by weight) on the catalyst before being newly supplied to the hydrodesulfurization unit (new catalyst standard)
VA2: Vanadium deposition amount (% by weight) that is expected to accumulate by being subjected to hydrodesulfurization using the same equipment
[3] Reacting the regenerated heavy oil desulfurization catalyst so that the sum of the allowable metal amount MPr represented by the formula (1) at each stage of the reaction tower packed with the regenerated heavy oil desulfurization catalyst is 0 or more. The method for recycling a heavy oil desulfurization catalyst according to [1] or [2], which is packed in a tower.
[4] The method for recycling a heavy oil desulfurization catalyst according to the above [3], wherein the regenerated heavy oil desulfurization catalyst is charged into a reaction tower so that a sum of metal allowable amounts MPr is 1 or more and 5 or less.

  ADVANTAGE OF THE INVENTION According to this invention, the recycling method of the heavy oil desulfurization catalyst which can reuse a used catalyst still more effectively can be provided.

FIG. 1 is a schematic diagram for explaining an example of the reactor of the present invention. FIG. 2 is a schematic diagram for explaining the downflow type fixed bed reactor used in the examples of the present invention.

  The present invention relates to a catalyst used in a hydrodesulfurization apparatus in which raw material heavy oil is introduced from the top side of a reaction tower packed with a catalyst and the hydrodesulfurized raw material heavy oil is discharged from the bottom side of the reaction tower in one apparatus. The recycling method of the present invention comprises a step of extracting the heavy oil desulfurization catalyst, a step of regenerating the extracted heavy oil desulfurization catalyst, and a step of filling the heavy oil desulfurization catalyst. Hereinafter, the method for recycling the heavy oil desulfurization catalyst of the present invention will be described in detail with reference to FIG. FIG. 1 is a diagram for explaining an example of the reactor of the present invention. In addition, the reactor shown in FIG. 1 is an example of the reactor of this invention to the last, and does not limit this invention.

[Hydrodesulphurization equipment]
As shown in FIG. 1, a hydrodesulfurization apparatus 10 according to the present invention is charged with raw material heavy oil L from a tower top side 12 of a reaction tower filled with a catalyst, and hydrodesulfurized raw material heavy oil L is supplied to the bottom of the reaction tower. Drain from side 14. The catalyst charged in the reaction tower is a heavy oil desulfurization catalyst, and the heavy oil desulfurization catalyst is divided into two or more stages.

  The hydrodesulfurization apparatus in the present invention performs desulfurization, denitrogenation, deoxygenation, and hydrocarbon hydrogenation and decomposition on heavy oil by hydrodesulfurization treatment. The hydrodesulfurization apparatus can perform not only hydrorefining such as desulfurization and denitrogenation, but also demetallization and asphaltene hydrocracking. With this in mind, hydrodesulfurization equipment is used not only for desulfurization of heavy oil, but also in combination with residual oil upgrading processes such as residual oil fluid catalytic cracking (RFCC), coker, and solvent debris. Sometimes used. Product heavy oil obtained by hydrodesulfurization equipment is used as, for example, RFCC raw material, coker raw material, and low sulfur product heavy oil.

  Next, the hydrodesulfurization process implemented with a hydrodesulfurization apparatus is demonstrated. The hydrodesulfurization treatment performed in the hydrodesulfurization apparatus is not particularly limited as long as heavy oil can be desulfurized. The hydrodesulfurization process performed by the hydrodesulfurization apparatus will be described by taking the hydrodesulfurization process using a fixed bed reactor as an example. The heavy oil used as the raw material for the hydrodesulfurization treatment includes residues such as atmospheric residual oil and vacuum residual oil. However, heavy oil does not include those consisting only of distillate oil such as kerosene, light oil, and vacuum gas oil. For example, heavy oil has a sulfur content of 1% by weight or more, a nitrogen content of 200% by weight or more, a residual carbon content of 5% by weight or more, a vanadium of 5 ppm or more and an asphaltene content of 0. 5 Including at least mass%. Examples of heavy oil include crude oil other than atmospheric residue, asphalt oil, pyrolysis oil, tar sand oil, and mixed oils thereof. The heavy oil used as a raw material for the hydrodesulfurization treatment is not particularly limited as long as it is as described above. It is preferably used as a raw material for treatment.

The reaction temperature of the hydrodesulfurization treatment is preferably 300 to 450 ° C, more preferably 350 to 420 ° C, still more preferably 370 to 410 ° C. The hydrogen partial pressure of the hydrodesulfurization treatment is preferably 7.0 to 25.0 MPa, and more preferably 10.0 to 18.0 MPa. The liquid space velocity of the hydrodesulfurization treatment is preferably 0.01 to 10 h ⁻¹ , more preferably 0.1 to 5 h ⁻¹ , further preferably 0.1 to ¹ h ⁻¹ . The hydrogen / raw oil ratio in the hydrodesulfurization treatment is preferably 500 to 2,500 Nm ³ / kl, and more preferably 700 to 2,000 Nm ³ / kl. The sulfur content and the metal content (vanadium, nickel, etc.) content of the product oil obtained by the hydrodesulfurization treatment can be adjusted, for example, by appropriately adjusting the reaction temperature in the hydrodesulfurization treatment.

[Heavy oil desulfurization catalyst]
The heavy oil desulfurization catalyst in the present invention is a catalyst that is used for hydrodesulfurization treatment of heavy oil at least once a catalyst (including a sulfurized catalyst) that is usually used for desulfurization of heavy oil. Usually, carbon, vanadium and the like are deposited on the catalyst by use. The heavy oil desulfurization catalyst is not particularly limited as long as it is used for hydrodesulfurization treatment of heavy oil. For example, an alumina catalyst having molybdenum supported on an alumina carrier is used as a heavy oil desulfurization catalyst. In this case, cobalt or nickel is used as a promoter.

  The alumina support may contain at least one of phosphorus, silicon and boron. The content in the heavy oil desulfurization catalyst in at least one of phosphorus, silicon and boron when converted in terms of oxide is preferably 30.0% by mass or less, more preferably 0.1 to 10.0% by mass. Yes, more preferably 0.2 to 5.0 mass%. However, the content of at least one of phosphorus, silicon, and boron in the catalyst is at least one of phosphorus, silicon, and boron, based on a reference mass that is oxidized at a temperature of 400 ° C. or higher and no weight loss due to heating occurs. The seed content is expressed in mass%.

  The content of molybdenum in the heavy oil desulfurization catalyst is preferably 0.1 to 25.0% by mass, more preferably 0.2 to 8.0% by mass. The content of cobalt or nickel in the heavy oil desulfurization catalyst is preferably 0.1 to 10.0% by mass, more preferably 0.2 to 8.0% by mass. The metal content in the heavy oil desulfurization catalyst represents the mass of the oxide of the metal to be measured in mass%, based on the oxidation mass at a temperature of 400 ° C. or higher and no loss due to heating. And

  Since heavy oil contains a large amount of asphaltenes and vanadium, carbon and vanadium are deposited on the heavy oil desulfurization catalyst used for hydrodesulfurization treatment of heavy oil. The carbon component covers the catalyst surface of the heavy oil desulfurization catalyst, and reduces the catalytic activity of the heavy oil desulfurization catalyst. However, the carbon content deposited on the heavy oil desulfurization catalyst can be removed by regeneration treatment such as solvent extraction and oxidative combustion treatment, and the catalytic activity of the heavy oil desulfurization catalyst can be increased. The carbon content in the used heavy oil desulfurization catalyst before the regeneration treatment is preferably 10 to 70% by mass, more preferably 0.2 to 8.0% by mass. If the carbon content in the heavy oil desulfurization catalyst is greater than 70% by mass, the catalyst activity does not increase sufficiently even after regeneration, or the catalyst needs to be regenerated at a high temperature to increase the catalyst activity. Therefore, the strength of the catalyst may be reduced. In addition, the carbon content in the heavy oil desulfurization catalyst is expressed by mass% with respect to the mass of the carbon in the target catalyst, based on the oxidation mass at a temperature of 400 ° C. or higher and the weight loss due to heating no longer occurs. Shall.

  The vanadium content in the used heavy oil desulfurization catalyst before the regeneration treatment is preferably 35% by mass or less, more preferably 20% by mass or less. If the vanadium content is greater than 35% by mass, the catalyst activity does not increase sufficiently even after regeneration, or the catalyst needs to be regenerated at a high temperature to increase the catalyst activity. The strength may decrease. Vanadium deposited on heavy oil desulfurization catalyst cannot usually be removed by regeneration treatment.

  The vanadium content in the spent catalyst is almost unchanged before and after the regeneration treatment. Therefore, based on the vanadium content in the used catalyst, it is possible to discriminate between a catalyst that can be regenerated and a catalyst that cannot be used even if it is regenerated before the regeneration treatment. Since it is useless to regenerate a catalyst that cannot be used even if it is regenerated, it is preferable to select and remove from the used catalyst those catalysts that cannot be clearly regenerated before the regeneration process.

The catalyst used for hydrodesulfurization treatment and the catalyst that was oxidized for regeneration treatment, especially the combustion treatment, changed the catalyst pore structure and the active metal loading state due to the heating of the catalyst during treatment, and the catalyst activity decreased. May end up. As an index for evaluating these, there are specific surface area and pore volume of the catalyst. The specific surface area and pore volume of the catalyst are gradually reduced by hydrodesulfurization treatment and adhesion of impurities, and are easily reduced by regeneration treatment. The specific surface area and pore volume of the used heavy oil desulfurization catalyst are preferably 70% or more of the specific surface area and pore volume of the new catalyst, respectively. The specific surface area of the spent fuel oil desulfurization catalyst is preferably a 60~220m ² / g, more preferably 100 to 200 m ² / g. The pore volume of the used heavy oil desulfurization catalyst is preferably 0.3 to 1.2 cc / g, more preferably 0.4 to 0.8 cc / g.

  The new catalyst is a catalyst that has been produced as a catalyst and has never been used for hydrodesulfurization treatment. Furthermore, the new catalyst includes a catalyst that has been once used for hydrodesulfurization treatment, but has been used for a short period of time due to troubles on the apparatus and used again as it is. In other words, even if it is temporarily used, the hydrogenation activity assumed from the beginning is still sufficient even if it is not specially activated or removed from the reactor and subjected to regeneration such as sorting, washing and oxidation. Catalysts that can be used as they are are also included in the new catalyst. The new catalyst may be a commercially available catalyst or a specially prepared catalyst. In addition, the new catalyst may be a catalyst that has been subjected to sulfurization treatment as a pretreatment for use in the hydrotreatment.

[Process for extracting heavy oil desulfurization catalyst]
The step of extracting the heavy oil desulfurization catalyst in the present invention comprises the m-th stage (m is an integer of 2 or more) heavy oil desulfurization catalyst and the n-th stage (n is n <m) from the top of the reaction tower. This is a step of extracting a heavy oil desulfurization catalyst satisfying an integer). The amount of vanadium accumulated in the catalyst in the reaction tower greatly depends on the packed portion of the reaction tower. The closer the position of the catalyst is to the top of the reaction tower, the more the amount of vanadium accumulated in the catalyst in the reaction tower is. growing. Therefore, the amount of vanadium accumulated in the m-stage heavy oil desulfurization catalyst from the tower top side of the reaction tower is smaller than the amount of vanadium accumulated in the n-stage heavy oil desulfurization catalyst from the tower top side of the reaction tower.

[Regeneration of the extracted heavy oil desulfurization catalyst]
The step of regenerating the extracted heavy oil desulfurization catalyst regenerates the heavy oil desulfurization catalyst extracted from the m-th stage from the top of the reaction tower. The regeneration process carried out in the process of regenerating the heavy oil desulfurization catalyst includes, for example, removal of oil, etc. by solvent washing, removal of carbon, sulfur, and nitrogen, etc. by oxidation treatment, and agglomerated or finely divided catalyst. Including selection of the catalyst in the normal shape by removing it. The oxidation treatment is preferably performed outside the reactor.

  In a preferred regeneration process of a spent catalyst with a large amount of carbon attached, the spent catalyst is first washed with a solvent. Preferred solvents include, for example, toluene, acetone, alcohol and petroleum such as naphtha, kerosene and light oil. In this cleaning treatment, for example, gas oil is circulated while the catalyst is in the hydrodesulfurization treatment reactor to wash the catalyst, and then a gas such as nitrogen gas at about 50 to 300 ° C. is circulated to dry the catalyst. . Alternatively, the gas oil may be circulated and washed and then extracted as it is, and the catalyst may be wetted with the gas oil and dried when necessary in order to prevent heat generation and spontaneous ignition. There is also a method in which the crushed and pulverized catalyst and scale are removed from the spent catalyst extracted from the reactor, and this is washed with light oil and further washed with naphtha to make it easier to dry the catalyst. When the amount of spent catalyst is small, a method of washing the catalyst with toluene is suitable for completely removing oil from the catalyst.

  In order to recover the catalytic activity of the catalyst from which oil and impurities have been removed by washing, it is necessary to further remove carbon deposited on the catalyst by oxidation treatment. The oxidation treatment is generally performed by a combustion treatment in which the atmospheric temperature and oxygen concentration are controlled. If the ambient temperature is too high or the oxygen concentration is too high, the catalyst surface will become high temperature, and the crystal form and state of the supported metal will change, or the pores of the carrier will decrease and the catalytic activity will decrease. There is a case. Further, if the ambient temperature is too low or the oxygen concentration is too low, removal of carbon by combustion may be insufficient and the catalyst activity may not be sufficiently recovered. The atmospheric temperature of the combustion treatment is preferably 200 to 800 ° C, more preferably 300 to 600 ° C.

  The oxygen concentration in the combustion treatment is preferably controlled in accordance with the combustion method, particularly the contact state between the combustion gas and the catalyst. For example, the oxygen concentration in the combustion treatment is preferably 1 to 21% by volume. The surface temperature of the catalyst is controlled by adjusting the atmospheric temperature, oxygen concentration, and atmospheric gas flow rate in the combustion process, and changes in the crystal structure of metal such as molybdenum and the support state of the crystal particles in the catalyst during the combustion process are suppressed. It is important to prevent a decrease in the specific surface area and pore volume of the catalyst.

  It is desirable to remove the powdered catalyst from the combustion-treated catalyst and use only a catalyst having a normal shape as a regenerated catalyst. If the pulverized catalyst remains in the catalyst, the catalyst layer in the reactor may become clogged and drifted, and the pressure loss of the fluid in the reactor may increase, resulting in normal operation of the reactor. It may not be possible to continue.

[Step of filling heavy oil desulfurization catalyst]
In the step of filling the heavy oil desulfurization catalyst, the heavy oil desulfurization catalyst regenerated at the nth stage from the top of the reaction tower is filled, and the new catalyst is filled in the stage where the reaction tower is empty. As described above, the amount of vanadium accumulated in the m-stage heavy oil desulfurization catalyst from the tower top side of the reaction tower is smaller than the amount of vanadium accumulated in the n-stage heavy oil desulfurization catalyst from the tower top side of the reaction tower. Therefore, the heavy oil desulfurization catalyst extracted and regenerated from the m-th stage from the tower top side of the reaction tower is charged with the n-th stage heavy oil from the tower top side of the reaction tower, thereby filling the n-th stage heavy oil from the reaction tower top side. The amount of vanadium accumulated in the desulfurization catalyst can be reduced, and the ability to desulfurize heavy oil in the entire reaction tower can be increased. Even if the amount of vanadium accumulated in the m-stage heavy oil desulfurization catalyst from the top of the reaction tower is high, the recovered heavy oil desulfurization catalyst is extracted from the m-th stage from the top of the reaction tower and regenerated. By filling the n-th stage from the top side, the amount of vanadium accumulated in the n-stage heavy oil desulfurization catalyst from the top side of the reaction tower can be reduced. Therefore, it is possible to reuse a spent catalyst that could not be reused due to the high amount of vanadium that has been accumulated in the past, and the spent catalyst can be reused more effectively.

  Since the m-th stage heavy oil desulfurization catalyst is extracted from the top of the reaction tower, the m-th part from the top of the reaction tower becomes empty. The empty stage may be filled with a catalyst regenerated by removing the p-stage (p> m) heavy oil desulfurization catalyst further away from the top of the reaction tower than the m-th stage. It may be filled. When the regenerated catalyst is charged, all of the catalyst in the reaction tower may be extracted, and again packed in the same number of stages and charged sequentially from the bottom of the tower.

[Metal tolerance MPr]
When the heavy oil desulfurization catalyst filled in the m-th stage is regenerated and used in the n-th stage, the allowable metal amount MPr represented by the following formula (1) is filled in the n + 1-th stage (where n + 1 <m). When the catalyst is regenerated and used in the same n + 1 stage, it is preferably larger than the metal allowable amount MPr. Thereby, the stage filled with the regenerated catalyst regenerated from the heavy oil desulfurization catalyst filled in the m-th stage can be appropriately selected, and the allowable metal amount MPr can be effectively increased.

MPr = (PV / 2Vv) × {8 × 10 ⁵ × (PD) ^1.3 } × (Sp / Vp) − (VA1 + VA2) (1)
In the formula (1), each symbol represents the following.
PV: Pore volume at the time of new catalyst (m ³ / kg)
Vv: Volume when vanadium is deposited by 1 wt% on a new catalyst of 1 kg = volume when considered as vanadium sulfide = 3.8 × 10 ⁻⁶ (m ³ /% kg)
PD: average pore diameter (m) for new catalyst
Sp: average outer surface area of one grain at the time of new catalyst (m ² )
Vp: average volume of one grain at the time of new catalyst (m ³ )
VA1: Vanadium deposition amount (% by weight) on the catalyst before being newly supplied to the hydrodesulfurization unit (new catalyst standard)
VA2: Vanadium deposition amount (% by weight) that is expected to accumulate by being subjected to hydrodesulfurization using the same equipment

  The allowable metal amount MPr in the above formula (1) is an index of the amount of vanadium deposited that can be allowed during the scheduled period of using the regenerated catalyst when the used catalyst is regenerated and reused as a regenerated catalyst. Larger metal allowance MPr allows a larger amount of vanadium deposition. When the allowable metal amount MPr is less than 0, the regenerated catalyst means that the vanadium deposition exceeds the allowable amount before the scheduled period for using the regenerated catalyst expires. The MPr value of the commercially available catalyst is usually 50 or less even when the vanadium deposition amount (VA1 + VA2) is 0% (new catalyst), 20 to 35 for a demetallized catalyst, and 10 to 25 for a desulfurized catalyst.

The first term of the above formula (1) represents the allowable amount of vanadium deposition at the time of the new catalyst, is determined by the initial physical properties such as the pore volume of the new catalyst, and does not change due to the use and regeneration treatment of the catalyst. PV is the pore volume of the new catalyst. Vv is the volume of vanadium when 1% by mass of vanadium is deposited on 1 kg of the new catalyst, and the vanadium is regarded as vanadium sulfide. The constant is 3.8 × 10 ⁻⁶ (m ³ /% kg). It is. In addition, it is considered that vanadium is deposited as vanadium sulfide in a normal hydrodesulfurization treatment. PD is the average pore diameter at the time of the new catalyst. The constant 8 × 10 ⁵ × (PD) ^1.3 is the diffusion depth of vanadium into the pores of the catalyst obtained from the analysis results of the various catalysts studied. The diffusion depth is usually proportional to (diffusion coefficient / reaction rate constant) ^-0.5 , and the diffusion coefficient is proportional to the catalyst pore diameter (see Rev. 5th edition, Chemical Engineering Handbook, Chapter 27). However, according to the study by the present inventors, it was found that the present catalyst is proportional to (catalyst pore diameter PD) ^1.3 as described above.

  Sp is the outer surface area of one grain at the time of the new catalyst, and is actually a value as an average value. Moreover, Vp is the volume of one grain at the time of a new catalyst, and is an average value similarly to Sp. (Sp / Vp) is the outer surface area per volume of the individual catalyst as an average, and is specified by the shape when the new catalyst is produced.

  VA1 in the second term is an actual value or a predicted value of the vanadium deposition amount (new catalyst reference mass%) accumulated when the new catalyst is used in the hydrodesulfurization apparatus for a predetermined period. VA2 is the actual value of the amount of vanadium deposited (new catalyst reference mass%) that is accumulated when the regenerated catalyst obtained by regenerating the new catalyst used in the hydrodesulfurization apparatus is further used in the hydrodesulfurization apparatus. When VA1 is less than 0.5% by mass, there is little deposition of vanadium on the catalyst, and the spent catalyst can be reused without regeneration. Accordingly, the spent catalyst to be regenerated preferably has a VA1 of 1.0% by mass or more. Although VA1 and VA2 are expressed as the amount of vanadium deposited on the catalyst, vanadium contained in the catalyst does not necessarily have to be deposited on the catalyst. For example, the amount of vanadium that enters the pores of the catalyst, enters the catalyst, or reacts with the catalyst component or the like is also included in the amount of vanadium deposited. In many cases, the VA1 and VA2 values of the spent catalyst are usually 0 to 70% by mass. Moreover, the value of VA1 and VA2 is as high as 30 to 70% by mass in the upstream part of the reaction zone of the A apparatus.

  The total allowable metal amount MPr represented by the above formula (1) in each stage of the reaction tower filled with the regenerated heavy oil desulfurization catalyst is preferably 0 or more, and preferably 1 or more and 5 or less. In this way, the reaction tower may be filled with a heavy oil desulfurization catalyst regenerated so as to be more preferably 3 or more and 5 or less. Thereby, before filling the heavy oil desulfurization catalyst extracted from the m-th stage from the tower top side of the reaction tower into the n-th stage from the tower top side of the reaction tower, before the scheduled period of using the regenerated catalyst expires, It is possible to prevent the deposition of vanadium from exceeding an allowable amount.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these Examples.

[Properties of raw fuel oil]
The following evaluation was performed about the raw material heavy oil used for each Example and a comparative example. Atmospheric residual oil was used as the raw material heavy oil.
(density)
The density of the atmospheric residue at 15 ° C. was measured according to JIS K 2249.
(Kinematic viscosity)
Based on JIS K 2283, the kinematic viscosity of the atmospheric residue at 50 ° C. was measured.
(Content of residual coal)
Based on JIS K 2270, the residual carbon content of atmospheric residual oil was measured.
(Content of asphaltene)
In accordance with IP143, the content of asphaltene in the atmospheric residue was measured.
(Sulfur content)
The sulfur content of the atmospheric residue was measured according to JIS K2541.
(Nitrogen content)
In accordance with JIS K 2609, the nitrogen content of the atmospheric residue was measured.
(Vanadium content)
The vanadium content of the atmospheric residue was measured in accordance with the Japan Petroleum Institute method JPI-5S-10-79.
(Nickel content)
The nickel content of the atmospheric residue was measured according to the Petroleum Institute method JPI-5S-11-79.
(Distillation properties)
Based on JIS K 2254, the distillation property of the atmospheric residue was measured.

[Catalyst properties]
The following evaluation was performed about the catalyst used for each Example and the comparative example.
For elemental analysis of vanadium and the like, after baking at 650 ° C. for 1 hour, ash was dissolved with acid for molybdenum and vanadium, and then by inductively coupled plasma optical emission spectrometry. For ash and lithium tetraborate for cobalt and nickel A bead was made from this mixture by high-frequency overheating and analyzed by X-ray fluorescence analysis. The carbon content is also 15% (the carbon content in the catalyst is expressed in mass% of the carbon in the target catalyst based on the oxidation of the target catalyst until it is not reduced at 400 ° C. or higher. The same shall apply hereinafter), preferably 10% or less. The carbon content is often about 10 to 70% at the used stage, but the carbon content can be removed from the catalyst by the regeneration treatment to reduce the content. If there is too much carbon, this will cover the catalyst surface and reduce catalyst activity, but if the carbon content is reduced by regeneration treatment, the activity can be recovered. For the analysis of carbon and sulfur, the ground sample was analyzed with a CS simultaneous analyzer. The average length of the catalyst was averaged by measuring the length in the direction perpendicular to the cross section of 10 particles arbitrarily extracted with calipers. The average outer surface area and average volume of one grain were calculated from the shape and average length of the particle cross-sectional area.

[Properties of the product oil]
The same evaluation as the evaluation of the properties of the above-mentioned raw material heavy oil was performed on the product oil obtained from the raw material heavy oil by hydrodesulfurization treatment in each Example and Comparative Example. Since the method for evaluating the properties of the product oil is the same as the method for evaluating the properties of the above-mentioned raw material heavy oil, description of the method for evaluating the properties of the product oil is omitted.

[Production of New Catalyst Used in Each Example and Comparative Example]
630 g of molybdenum oxide and 150 g of basic nickel carbonate in terms of NiO were dissolved in ion-exchanged water using 180 g of malic acid to prepare 2000 ml of impregnation liquid. The water content of this impregnating solution was prepared so as to match the water absorption amount of the following carrier, and 4,000 g of a four-leaf type alumina carrier (specific surface area 230 m ² / g, average pore diameter 120 angstrom, pore volume 0.69 ml / g). ) Was impregnated in this impregnating solution for 15 minutes. The alumina support impregnated with the impregnating solution was dried at 120 ° C. for 3 hours and calcined at 500 ° C. for 5 hours to obtain a new catalyst 1.

[Production of regenerated catalyst used in each example and comparative example]
Example 1
-Hydrodesulfurization treatment with new catalyst-
As shown in FIG. 2, the downflow type fixed bed reactor is divided into 4 beds (4 parts by volume), and a commercially available demetallization catalyst is placed in the uppermost bed (hereinafter referred to as “first bed”). The remaining 3 beds (second to fourth beds) were filled with the new catalyst 1. The physical properties and metal tolerance of the new catalyst 1 are shown in Table 1 below. After performing the normal preliminary sulfidation treatment, the sulfur content becomes constant (0.3% by mass or less) under the reaction conditions shown in Table 3 below using atmospheric residual oil having the properties shown in Table 2 below. The hydrodesulfurization treatment was performed for 330 days while adjusting the reaction temperature. The reaction temperature on the 330th day was 396 ° C. The properties of the product oil 1 obtained from the atmospheric residue by hydrodesulfurization treatment are shown in Table 4 below.

-Reproduction processing-
The catalyst 1 in the reactor was washed with light oil, dried and cooled while circulating nitrogen gas, and then the spent catalyst was taken out from the second to fourth beds of the reactor. The used catalyst taken out from the third bed is hereinafter referred to as a used catalyst 1 and the used catalyst taken out from the fourth bed is hereinafter referred to as a used catalyst 2. The physical properties and metal tolerances of the used catalyst 1 and the used catalyst 2 are shown in Table 1 below. Thereafter, lump and powder were removed from the spent catalyst 1 by sieving. About 100 g of the spent catalyst 1 from which lump and powder were removed was supplied 100% nitrogen gas at a flow rate of 100 cc / min using a rotary calciner (rotation speed: 5 rev / min), Each was dried for 1 hour at a heating temperature of 300 ° C. Thereafter, while supplying a mixed gas of 50% nitrogen gas-50% air at a flow rate of 100 cc / min, the mixture was calcined at a calcining temperature of 450 ° C. for 3 hours. The pulverized product was removed from the spent catalyst 1 to obtain a regenerated catalyst 1. The regenerated catalyst 2 was obtained from the spent catalyst 2 in the same manner. The physical properties and metal tolerance of the regenerated catalyst 1 and the regenerated catalyst 2 are shown in Table 1 below.

-Hydrodesulfurization treatment with regenerated catalyst-
The down flow type fixed bed reactor is divided into 4 beds (4 parts by volume), the first bed is filled with a commercial demetallized catalyst, the second bed just below it is loaded with the regenerated catalyst 2, and the third and The fourth bed was filled with new catalyst 1. After performing normal preliminary sulfidation treatment, the sulfur content was constant (0.3% by mass or less) under the reaction conditions shown in Table 3 below using atmospheric residual oil having the properties shown in Table 2 below. The hydrodesulfurization treatment was performed for 330 days while adjusting the reaction temperature so that The reaction temperature on the 330th day was 400 ° C. Table 4 below shows the properties of the product oil 2A obtained from the atmospheric residue by hydrodesulfurization treatment.

-Reproduction processing-
The regenerated catalyst 3A was obtained by regenerating the used regenerated catalyst 2 in the same manner as in the regeneration process of the used catalyst 1 described above. The physical properties and metal tolerance of the regenerated catalyst 3A are shown in Table 1 below.

(Comparative Example 1)
-Hydrodesulfurization treatment with new catalyst-
In the same manner as in Example 1, hydrodesulfurization treatment was performed under the reaction conditions shown in Table 3 below using the atmospheric residual oil having the properties shown in Table 2 below and the new catalyst 1.
-Reproduction processing-
In the same manner as in Example 1, the used catalyst 1 and the used catalyst 2 were regenerated to obtain a regenerated catalyst 1 and a regenerated catalyst 2.

-Hydrodesulfurization treatment with regenerated catalyst-
The downflow type fixed bed reactor is divided into 4 beds (4 parts by volume), the first bed is filled with a commercial demetallized catalyst, the second and third beds just below it are charged with the new catalyst 1, The regenerated catalyst 2 was filled in the fourth bed. After performing normal preliminary sulfidation treatment, the sulfur content was constant (0.3% by mass or less) under the reaction conditions shown in Table 3 below using atmospheric residual oil having the properties shown in Table 2 below. The hydrodesulfurization treatment was performed for 330 days while adjusting the reaction temperature so that The reaction temperature on the 330th day was 413 ° C. Table 4 below shows the properties of the product oil 2B obtained from the atmospheric residue by the hydrodesulfurization treatment.

-Reproduction processing-
A used regeneration catalyst 2 was regenerated by the same method as the above regeneration treatment of the used catalyst 1 to obtain a regenerated catalyst 3B. The physical properties and metal tolerance of the regenerated catalyst 3B are shown in Table 1 below.

  From the results of Example 1 and Comparative Example 1, the spent catalyst filled in the fourth bed was compared with the case where the spent catalyst filled in the fourth bed was regenerated and filled in the fourth bed as it was. It was found that the sulfur content and asphaltene content of the product oil obtained by the hydrodesulfurization treatment can be reduced by regenerating and filling the second bed.

DESCRIPTION OF SYMBOLS 1 1st bed 2 2nd bed 3 3rd bed 4 4th bed 10 Hydrodesulfurization equipment 12 Tower top side of reaction tower 14 Tower bottom side of reaction tower

Claims (4)

In one apparatus, recycling of a catalyst used in a hydrodesulfurization apparatus in which raw material heavy oil is introduced from the top side of a reaction tower packed with a catalyst and hydrodesulfurized raw material heavy oil is discharged from the bottom side of the reaction tower. A method,
The heavy oil desulfurization catalyst charged in the reaction tower is divided into two or more stages, and the m-th stage (m is an integer of 2 or more) heavy oil desulfurization catalyst and the top of the reaction tower from the top of the reaction tower. Extracting the n-th stage (n is an integer satisfying n <m) heavy oil desulfurization catalyst from the side;
Regenerating the heavy oil desulfurization catalyst extracted from the m-th stage from the top of the reaction tower;
The regenerated heavy oil desulfurization catalyst is packed in the nth stage from the tower top side of the reaction tower, and the regenerated catalyst or new catalyst is extracted from the stage farther from the tower top of the reaction tower than the mth stage. And a step of filling the m-th stage with a heavy oil desulfurization catalyst recycling method. When the heavy oil desulfurization catalyst charged in the m-th stage is regenerated and used in the n-th stage, the allowable metal amount MPr expressed by the following formula (1) is charged in the n + 1-th stage (where n + 1 <m). The method for reusing a heavy oil desulfurization catalyst according to claim 1, wherein the catalyst is larger than the allowable metal amount MPr when regenerated and used in the same n + 1 stage.
MPr = (PV / 2Vv) × {8 × 10 ⁵ × (PD) ^1.3 } × (Sp / Vp) − (VA1 + VA2) (1)
In the formula (1), each symbol represents the following.
PV: Pore volume at the time of a new catalyst (m ³ / kg)
Vv: Volume when vanadium is deposited on 1 kg of new catalyst on the weight of 1 wt%, assuming that it is vanadium sulfide = 3.8 × 10 ⁻⁶ (m ³ /% kg)
PD: average pore diameter (m) for new catalyst
Sp: average outer surface area of one grain at the time of new catalyst (m ² )
Vp: average volume of one grain at the time of a new catalyst (m ³ )
VA1: Vanadium deposition amount (% by weight) on the catalyst before being newly supplied to the hydrodesulfurization unit (new catalyst standard)
VA2: Vanadium deposition amount (% by weight) that is expected to accumulate by being subjected to hydrodesulfurization using the same equipment The regenerated heavy oil desulfurization catalyst is adjusted so that the sum of the allowable metal amount MPr represented by the formula (1) at each stage of the reaction tower filled with the regenerated heavy oil desulfurization catalyst becomes 0 or more. The method for recycling the heavy oil desulfurization catalyst according to claim 2 , wherein the reaction tower is packed.   The method for reusing a heavy oil desulfurization catalyst according to claim 3, wherein the regenerated heavy oil desulfurization catalyst is charged into the reaction tower so that a sum of the metal allowable amount MPr is 1 or more and 5 or less.

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