JP5294663B2 - Method for recycling FT catalyst in FT synthetic oil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To selectively separate highly reactive catalyst particles from Fisher Tropsch synthesis slurry and recycle them to a reactor. <P>SOLUTION: By magnetically separating the catalyst contained in the slurry by 2 stages, higher magnetic particles are separated by a first high gradient magnetic separation process and recycled to the reactor, since they are highly active, and in the second magnetic separation process, particles having a lower magnetism is separated and discharged to the outside of the system. Thus, it becomes possible to selectively recycle the highly active residual catalyst. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention provides a reactor comprising a slurry comprising a synthetic crude oil obtained by a Fischer-Tropsch synthesis method (hereinafter abbreviated as “FT synthesis method”) using carbon monoxide and hydrogen as raw materials and a Fischer-Tropsch catalyst having magnetism. In order to obtain a synthetic crude oil, the catalyst having a large magnetism and a high activity in the slurry is separated and circulated to the reactor, and the catalyst having a small magnetism and the inert catalyst is discharged out of the system. The present invention relates to a method of selectively recycling an FT catalyst having high magnetism and high activity, which is processed by a two-stage high gradient magnetic separator.

  In recent years, clean liquid fuels that are low in sulfur content and aromatic hydrocarbon content and that are friendly to the environment have been demanded from the viewpoint of reducing environmental impact. Therefore, in the petroleum industry, an FT synthesis method using carbon monoxide and hydrogen as raw materials is being studied as a method for producing clean fuel. According to the FT synthesis method, a liquid fuel base material having a high paraffin content and not containing a sulfur content, for example, a diesel fuel base material can be produced. For example, environmentally-friendly fuel oil is also proposed in Patent Document 1.

JP 2004-323626 A

On the other hand, FT synthesis catalysts using carbon monoxide and hydrogen as raw materials have hitherto been many iron-based solid catalysts, but recently, cobalt-based solid catalysts have also been developed because of their high activity.
Here, the reaction form of the FT synthesis method is often an embodiment of a slurry in which a solid catalyst is suspended in a product hydrocarbon. Therefore, in addition to obtaining a synthetic crude oil containing no catalyst, it is necessary to recover and reuse the catalyst in the resulting FT synthesis slurry from the viewpoint of cost reduction of the process.

Since a slurry in which the catalyst is suspended is obtained from the reactor for FT synthesis, it is preferable to collect and reuse the catalyst from the reactor while obtaining a synthetic crude oil containing no catalyst.
In the reactor for FT synthesis, the catalyst may be oxidized by oxygen-containing compounds, and coke deposition may occur on the catalyst due to the FT reaction. In any case, the catalyst becomes less active, thereby reducing the catalyst efficiency. To do.

Since a slurry in which the catalyst is suspended is obtained from the reactor for FT synthesis, it is preferable to collect and reuse the catalyst from the reactor while obtaining a synthetic crude oil containing no catalyst.
In the reactor for FT synthesis, the catalyst may be oxidized by an oxygen-containing compound, and coke deposition may occur on the catalyst due to the FT reaction. descend.

  In the recovery and reuse of the catalyst, it is desired to discard the catalyst having the reduced reaction activity and to recover and reuse only the highly active catalyst.

  The present inventors have found that the magnetic properties of the FT catalyst particles having low reaction activity are weak. For example, catalyst particles on which coke is deposited have a reduced magnetism (magnetic susceptibility) per unit weight. For example, cobalt metal has a low magnetic susceptibility in an oxidized state, so that it is highly active based on the magnitude of magnetism. It is effective to select the catalyst. If the highly active recovered catalyst is selectively recycled to the FT reactor, the reaction efficiency can be improved.

That is, according to the first aspect of the present invention, a slurry containing a synthetic crude oil obtained by the Fischer-Tropsch process and a Fischer-Tropsch catalyst having magnetism is extracted from a reactor for Fischer-Tropsch synthesis, and the slurry is extracted into a two-stage high gradient. Let's treat with a magnetic separator, where
In the first high gradient magnetic separator separating a large catalytic magnetic from the slurry, harvested and which is reused by circulating the Fischer-Tropsch reactor, separation conditions of the first high gradient separator Has a magnetic field strength of 15000 gauss or more, a liquid temperature (treatment temperature) in the separator of 100 ° C. to 400 ° C., a liquid residence time of 10 seconds to 50 seconds,
In the second high gradient magnetic separator, the separated catalyst is discharged out of the system. The separation condition of the second high gradient separator is that the magnetic field strength is 15000 gauss or more, and the liquid temperature (treatment temperature) in the separator is 100 ° C. to 400 ° C., liquid residence time is 50 seconds or more,
The present invention relates to a method for recycling a Fischer-Tropsch catalyst, characterized by obtaining synthetic crude oil.

  According to a second aspect of the present invention, in the first aspect of the present invention, the magnetism of the Fischer-Tropsch catalyst removed from the slurry by the first high gradient magnetic separator and returned to the Fischer-Tropsch reactor is the Fischer-Tropsch reaction. The present invention relates to a method for recycling a Fischer-Tropsch catalyst, which is larger than the magnetism of the Fischer-Tropsch catalyst in a slurry at the outlet of the vessel.

  FT reaction synthetic crude oil with reduced residual catalyst is obtained, and a highly active residual catalyst having high magnetism can be selectively recycled.

The present invention is described in detail below.
Hereinafter, a preferred embodiment of the present invention will be described with reference to FIG. As shown in FIG. 1, a synthesis gas containing carbon monoxide gas and hydrogen gas is supplied from a line 1, and liquid hydrocarbons are generated by an FT synthesis reaction in an FT synthesis reactor 10. The synthesis gas can be obtained by, for example, hydrocarbon reforming as appropriate. Typical hydrocarbons include methane, natural gas, LNG (liquefied natural gas), and the like. For example, a partial oxidation reforming method (POX) using oxygen, an autothermal reforming method (ATR) that is a combination of the partial oxidation reforming method and the steam reforming method, a carbon dioxide gas reforming method, or the like can be used. .

Next, FT synthesis will be further described with reference to FIG.
FT synthesis comprises an FT synthesis reactor 10. The reactor 10 can be, for example, a bubble column reactor, which is an example of a reactor that synthesizes synthesis gas into liquid hydrocarbons, and synthesizes liquid hydrocarbons from synthesis gas by an FT synthesis reaction. Functions as a reactor for FT synthesis.

The main body of the reactor 10 is a substantially cylindrical metal container having a diameter of about 1 to 20 m, preferably about 2 to 10 m. The height of the reactor body is about 10 to 50 m, preferably about 15 to 45 m. Inside the reactor main body, a slurry in which solid catalyst particles are suspended in liquid hydrocarbon (product of FT synthesis reaction) is accommodated.
Part of the slurry is discharged from the middle of the reactor to the separators 20 and 30 via the line 3. From the top of the reactor 10, unreacted synthesis gas or the like is discharged through the line 2, and a part of it is returned to the line 1 and circulated through the reactor 10 as appropriate.

  The synthesis gas supplied from the outside through the synthesis gas supply pipe 1 is injected into the slurry inside the reactor 10 from a synthesis gas supply port (not shown). The synthesis gas undergoes a liquid hydrocarbon synthesis reaction (FT synthesis reaction) by a contact reaction that contacts catalyst particles. Specifically, as shown in the chemical reaction formula (1) below, hydrogen gas and carbon monoxide gas cause a synthesis reaction.

2nH ₂ ten _{nCO → (-CH 2 -) n} + nH 2 0. . . . (1)

Specifically, synthesis gas is introduced from the line 1 to the bottom of the reactor 10 to raise the slurry stored in the reactor 10. At this time, in the reactor, carbon monoxide and hydrogen gas contained in the synthesis gas react by the above-described FT synthesis reaction to generate hydrocarbons. Although heat is generated during this synthesis reaction, the heat is removed by an appropriate cooling means.
The FT catalyst includes a supported type and a deposited type, but in any case, it is a solid particle containing an iron group metal. An appropriate amount of metal is contained in the solid particles, but 100% metal may be used. The iron group metal is exemplified by iron, and cobalt is preferable from the viewpoint of high activity.

The composition ratio of the synthesis gas supplied to the FT synthesis reactor 10 is adjusted to a composition ratio (for example, H ₂ : CO = 2: 1 (molar ratio)) suitable for the FT synthesis reaction. In addition, the synthesis gas supplied to the reactor 10 is pressurized to a pressure (for example, 3.6 MPaG) appropriate for the FT synthesis reaction by an appropriate compressor (not shown). However, the compressor may not be provided.

  Thus, the liquid hydrocarbon synthesized in the reactor 10 is taken out from the reactor 10 as a slurry in which catalyst particles are suspended from a line 3 in the middle of the reactor 10 and used for a catalyst separation and recovery process.

In the catalyst separation and recovery process, as shown in the figure, two high gradient magnetic separators 20 and 30 are arranged in series.
The high gradient magnetic separators 20 and 30 have different operating conditions and the like so that the magnetism of the catalyst separated and recovered by each separator is different.

That is, the first high gradient magnetic separator 20 separates the stronger magnetic catalyst particles, and the stronger magnetic catalyst particles are still highly reactive particles, which are recycled to the FT reactor. . The degree of magnetism to be separated can be set in advance. For example, the magnetism of the FT catalyst removed from the slurry by the first high gradient magnetic separator and returned to the FT reactor is determined at the FT reactor outlet. It can be greater than the magnetism of the FT catalyst in the slurry. Thus, it is possible to selectively recycle only the FT catalyst having higher magnetism and higher reaction activity than the catalyst in the slurry to the FT reactor.
The magnetic measurement method is not particularly limited, but a magnetic susceptibility (emu / g) measured by, for example, a SQUID (superconducting quantum interference device) apparatus or the like can be preferably exemplified. Further, the magnetism of the FT catalyst returned to the FT reactor is not particularly limited as long as it is larger than the magnetism of the FT catalyst in the slurry at the FT reactor outlet. It is preferable that it is larger by 0.5% or more and 1.0% or more based on the susceptibility of the FT catalyst in the slurry.

Since the catalyst separated and recovered from the initial treatment by the high gradient magnetic separator 20 is still highly active as described above, it is returned to the reactor 10 by the line 21 and reused.
The remaining liquid from which the strong magnetic particles have been separated and removed is then sent to the next high gradient magnetic separator 30 via the line 22.

  The catalyst separated and recovered from the next high-gradient magnetic separator 30 is weak in magnetism, and its activity is reduced. Therefore, the catalyst is discharged out of the reaction system and discarded without being reused.

  Hereinafter, the separation operation by the high gradient magnetic separator 20 will be described. In this step, the magnetic fine particles contained in the extracted FT synthetic crude oil are separated and removed by the high gradient magnetic separator 20.

  That is, the FT synthetic crude oil is processed by the high gradient magnetic separator 20 to separate and remove the magnetic fine particles. It has also been found that the iron group metal as the FT synthesis catalyst has a certain magnetic susceptibility and exhibits paramagnetism, whether iron or cobalt. Therefore, removal by magnetic separation is quite effective.

  The high gradient magnetic separator 20 used in the present invention has a ferromagnetic packing disposed in a uniform high magnetic field space generated by an external electromagnetic coil, and is usually 1 to 20 k gauss / cm generated around the packing. It is a magnetic separator designed to attach ferromagnetic or paramagnetic particulate matter to the surface of the packing by a high magnetic field gradient, separate them, and wash the attached particles. For example, as the high gradient magnetic separator, a commercially available machine known by a registered trademark “FEROSEP” or the like can be used.

  As the ferromagnetic filler, an aggregate of ferromagnetic fine wires such as steel wool or steel net having a diameter of 1 to 1000 μm, expanded metal, and shell-shaped metal strips are usually used. As the metal, stainless steel having excellent corrosion resistance, heat resistance and strength is preferable.

  In addition, as proposed in JP-A-7-70568, a ferromagnetic metal piece is a plate-like body having two surfaces, and the area of the larger surface of the two surfaces is the diameter. R = equal to the area of a circle of 0.5 to 4 mm, the ratio of R to the maximum thickness d of the plate, R / d is in the range of 5 to 20, and the plate is mainly made of Fe A ferromagnetic metal piece made of an Fe—Cr alloy containing 5 to 25 wt% of Cr, 0.5 to 2 wt% of Si, and 2 wt% or less of C as components can also be preferably used.

  In the step of separating the magnetic fine particles in the slurry by the high gradient magnetic separator 20, the fraction is introduced into the magnetic field space of the high gradient magnetic separator 20, and the magnetic fine particles are placed in the ferromagnetic packing placed in the magnetic field space. To remove from the slurry. Next, the process of washing and removing the magnetic fine particles adhering to the packing has a limit in the amount of magnetic fine particles that can be trapped in the packing of a certain area, and if the trapped amount reaches a certain amount or the limit amount, the trapped magnetic Fine particles are washed away from the packing. This washing and removing step is performed by cutting off the magnetic field to desorb the magnetic fine particles, and discharging the magnetic fine particles outside the magnetic separator with the washing liquid. The magnetic separation conditions for the magnetic fine particles contained in the slurry and the cleaning removal conditions for the magnetic fine particles trapped in the packing will be described below.

As a separation condition of the high gradient magnetic separator 20, the magnetic field strength is required to be 15000 gauss or more. Separation machine of the liquid temperature (process temperature) is essential 100 ° C. or higher 400 ° C. or less, 1 00 is preferably 300 ° C. inclusive ° C., preferably 100 ° C. or higher 200 ° C. The following further. Liquid residence time (residence time), it is essential above 10 seconds 50 seconds or less, good preferable more than 50 seconds.
In the present invention, the high gradient magnetic separator 20 can separate particles by magnetism by appropriately setting the separation conditions. For example, the magnetism of the FT catalyst removed from the slurry by the first high gradient magnetic separator and returned to the FT reactor can be greater than the magnetism of the FT catalyst in the slurry at the FT reactor outlet. .

  Next, if the magnetic separation operation of the magnetic fine particles is continued, the removal rate decreases as the amount of the magnetic fine particles trapped in the packing increases. Therefore, in order to maintain the removal rate, it is necessary to perform a washing and removing step of discharging the captured magnetic fine particles to the outside of the magnetic separator after passing oil for a certain time. In actual industrial operation, the liquid containing magnetic fine particles may bypass the magnetic separator during this washing and removal process. However, if the cleaning time is long, the amount of magnetic fine particles flowing into the next process increases and is removed. Since the rate is lowered, a preliminary separator for switching may be provided if necessary.

  In washing and removing, in the present invention, the liquid obtained after magnetic separation can be used as a washing liquid.

  In the washing and removing step, the magnetic field around the packing is lost (the power supply to the magnetic coil for the magnetic separator is stopped), and the cleaning liquid is introduced from the bottom of the separator tower via the line 24 and is simply attached to the packing. This is an operation to wash away magnetic fine particles. The cleaning liquid is discharged from the line 25. As cleaning conditions, the cleaning liquid linear velocity is 1 to 10 cm / sec, preferably 2 to 6 cm / sec.

The magnetic separation process will be described below with reference to FIG.
FIG. 2 is a schematic simplified view of the high gradient magnetic separator 20 used in the present invention. The separation part of the high gradient magnetic separator 20 forms a vertical packed tower and is filled with a ferromagnetic packing. The packed bed 22 filled with the packing is magnetized by the magnetic lines generated by the electromagnetic coil 23 outside the tower to form a high gradient magnetic separation part. This portion is a uniform high magnetic field space generated by the external electromagnetic coil. The liquid heated to an appropriate temperature passes through the separation part from the line 3 from below at a predetermined flow rate, preferably at a flow rate that makes the liquid residence time 15 seconds or more, during which magnetic fine particles adhere to the surface of the packing. To be removed.

  While the FT synthetic crude oil is passing through the magnetic separator 20, the washing liquid is bypassed through a washing oil bypass line (not shown), and when the washing liquid is washing the magnetic separator 20, the slurry is slurry bypass line (not shown). 2) and can be directly fed to the subsequent magnetic separator 30. In this way, it is possible to perform switching between removal operation, cleaning operation, and repeated continuous operation. The washing and removing step can be performed with reference to the method described in JP-A-6-200260. The structure and operation of the second high gradient magnetic separator 30 described below are the same.

In the subsequent high gradient magnetic separator 30 of the second magnetic separation step, the same operation as in the first magnetic separation step can be performed. However, the magnetically weaker particles are magnetically separated. As described above, the catalyst remaining in the liquid component fed to the second high gradient magnetic separator 30 has already collected the effective catalyst in the first stage, and the activity of the residual catalyst is low. Therefore, it is appropriate to separate it as much as possible and discharge it out of the system. As a separation condition of the high gradient magnetic separator 30, the magnetic field strength is required to be 15000 gauss or more , and preferably 20000 gauss or more. Separation machine of the liquid temperature (process temperature) is essential 100 ° C. or higher 400 ° C. or less, 1 00 is preferably 300 ° C. inclusive ° C., preferably 100 ° C. or higher 200 ° C. The following further. The liquid residence time (residence time) is preferably 50 seconds or more.
Here, since the particles removed in the second magnetic separation step have weak magnetism and low activity, they are discharged from the line 31 to the outside of the system without being recycled to the reactor 10, and are preferably discarded.
The liquid component from which the particles have been captured and removed is sent from the line 32 to the next rectification column 40, for example, for subsequent processing.
In the high gradient magnetic separator 30 of the second magnetic separation step, it is possible to remove many residual catalysts by appropriately adjusting the operating conditions. Therefore, according to the present invention, the residual catalyst can be removed. FT synthetic crude oil with reduced is obtained.

Next, referring again to FIG. 1, the FT synthetic crude oil from which the particles have been separated by the separator 30 is then sent to the rectification tower 40 where it is rectified and subjected to various purification processes such as hydrogenation. Applied to become a product.
That is, the liquid component obtained by the separation process in the magnetic separation steps 20 and 30 is put into the rectifying column 40 and fractionated. For example, a naphtha fraction (boiling point is less than 150 ° C.) passes from the line 41 to the middle. A fraction (boiling point 150 to 350 ° C.) is fractionated from line 42 and a wax fraction (boiling point 350 ° C. or higher) is fractionated from line 43. Although it is fractionated into 3 fractions in the figure, it may be 2 fractions or 3 fractions or more. Moreover, it can also use for the following appropriate refinement | purification processes, without being especially distilled.

In the present invention, catalyst particles contained in an FT synthetic crude oil obtained by an FT synthesis method using carbon monoxide and hydrogen as raw materials are separated by a magnetic separator, and a highly active catalyst is effectively recovered and recycled. The weak and low-activity magnetic fine particles can be used in a method of discharging out of the system.
The following examples illustrate the invention.

Example 1
A synthesis gas containing carbon monoxide and hydrogen gas obtained by reforming natural gas as main components is sent to a bubble column type hydrocarbon synthesis reactor (FT synthesis reactor) 10 and an FT catalyst (average particle size) Liquid hydrocarbons are synthesized by reacting in a slurry in which 100 μm in diameter and 30% by weight of cobalt as an active metal are suspended. The liquid hydrocarbon synthesized in the FT synthesis reactor is taken out in line 3 as a slurry containing FT catalyst particles.

  The taken slurry (FT catalyst concentration: 100 ppm by mass) is led to a first high gradient magnetic separator (electromagnetic type high gradient magnetic separator (FEROSEP (registered trademark))) 20 arranged at the rear stage of the FT synthesis reactor. A part of the FT catalyst particles (magnetism greater than that of the FT catalyst particles in the slurry at the outlet of the FT reactor) and the FT catalyst particles that could not be captured by the first high gradient magnetic separator 20 under the processing conditions shown in Table 1. Separated into a liquid component (liquid A).

  The FT catalyst particles having a large magnetism separated by the first high gradient magnetic separator and not deactivated are returned to the FT synthesis reactor 10 via the line 21, and the liquid component (liquid A) is returned to the second high gradient magnetic field. It leads to the separator 30 and further separates into FT catalyst particles, which are solid components, and a liquid component (liquid B) under the processing conditions shown in Table 1. The FT catalyst particles with low magnetism and reduced catalytic activity separated by the second high gradient magnetic separator 30 are discarded from the line 31 to the outside of the system, and the liquid component (liquid B) is introduced into the rectification column 40. Fractionation, line 41 to naphtha fraction (boiling point less than 150 ° C.), line 42 to middle distillate (boiling point 150 to 350 ° C.) and column bottom line 43 to wax fraction (boiling point 350 ° C. or more) ) And fractionated. Further, the middle fraction is treated with a hydroisomerization apparatus (not shown), and the wax fraction is treated with a hydrocracking apparatus (not shown), followed by line blending to a second fractionator (not shown). To make a diesel fuel base material.

At this time, the magnetic susceptibility of the FT catalyst particles contained in the slurry of the line 3 at the outlet of the FT reactor is 7.30 emu / g, and is separated and removed by the first high gradient magnetic separator 20. The magnetic susceptibility of the FT catalyst particles recycled to the vessel 10 was 7.36 emu / g.
Further, the catalyst concentration of the FT catalyst particles at the outlet of the second high gradient magnetic separator 30 was 9.6 mass ppm.

Here, the magnetic susceptibility is a value measured using a SQUID (superconducting quantum interference device) magnetometer (MPMS-5 manufactured by Quantum Design) (hereinafter the same).
The catalyst concentration (mass ppm) is a value calculated on the basis of the weight of the treated oil based on the measurement result of the laser diffraction particle size distribution analyzer SALD-3100 manufactured by Shimadzu Corporation (hereinafter the same). .

(Examples 2 to 5)
The same processing as in Example 1 was performed except that the processing conditions of the first and second high gradient magnetic separators 20 and 30 were changed. Table 1 shows the magnetic susceptibility of the recycled FT catalyst particles and the catalyst concentration at the outlet of the second high gradient magnetic separator 30.

(Comparative Example 1)
The same treatment as in Example 1 except that a sintered metal filter having an opening of 10 μm was used instead of the first and second high gradient magnetic separators 20 and 30 to separate the FT catalyst particles from the slurry. Went. Table 1 shows the magnetic susceptibility of the recycled FT catalyst particles and the catalyst concentration in the treated oil at the filter outlet (for convenience, this concentration is shown in the catalyst concentration column at the outlet of the second magnetic separator 30 in Table 1). .

(result)
When the FT catalyst particles are removed by the filter as in Comparative Example 1 and recycled, the catalyst having low magnetism and reduced activity is also returned to the FT reactor. On the other hand, as in the example, all of the FT catalyst particles separated by the first high gradient magnetic separator 20 and returned to the FT reactor are higher in magnetism than the FT catalyst particles in the FT reactor outlet slurry. It can be seen that the high activity is recycled to the reactor.

  In any of the examples in which the second high-gradient magnetic separator was introduced, the FT catalyst concentration in the liquid B at the outlet of the second magnetic separator was reduced to less than 10 mass ppm, and the magnetic separator was used. It can be seen that the particle removal effect is equal to or greater than that of Comparative Example 1 using only a filter.

A fuel production plant including an FT synthesis reactor 10 and magnetic separators 20 and 30 for magnetically separating magnetic fine particles in FT synthetic crude oil. It is a model schematic diagram of the high gradient magnetic separators 20 and 30 used for this invention.

Explanation of symbols

10 FT synthesis reactor 20 first high gradient magnetic separator 30 second high gradient magnetic separator 40 rectifying tower for fractionating FT synthetic crude oil

Claims (2)

A slurry containing a synthetic crude oil and a magnetic Fischer-Tropsch catalyst obtained by a Fischer-Tropsch process is extracted from a Fischer-Tropsch synthesis reactor, and the slurry is processed by a two-stage high gradient magnetic separator. here,
The first high gradient magnetic separator separates and collects a magnetically large catalyst from the slurry, which is recycled to the Fischer-Tropsch reactor and reused. The separation conditions of the first high gradient separator Has a magnetic field strength of 15000 gauss or more, a liquid temperature (treatment temperature) in the separator of 100 ° C. to 400 ° C., a liquid residence time of 10 seconds to 50 seconds,
In the second high gradient magnetic separator, the separated catalyst is discharged out of the system. The separation condition of the second high gradient separator is that the magnetic field strength is 15000 gauss or more, and the liquid temperature (treatment temperature) in the separator is 100 ° C. to 400 ° C., liquid residence time is 50 seconds or more,
A method for recycling a Fischer-Tropsch catalyst, characterized by obtaining synthetic crude oil.   The magnetism of the Fischer-Tropsch catalyst removed from the slurry by the first high gradient magnetic separator and returned to the Fischer-Tropsch reactor is greater than the magnetism of the Fischer-Tropsch catalyst in the slurry at the Fischer-Tropsch reactor outlet. The method for recycling a Fischer-Tropsch catalyst according to claim 1, wherein

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