JP2012081379A - Method for regenerating adsorbent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for regenerating an adsorbent which can prevent remaining of sulfur on the adsorbent and sulfur leakage to raw materials.SOLUTION: The method for regenerating an adsorbent which regenerates an adsorbent for adsorbing sulfur in the raw materials includes a first heating process for heating a regeneration gas and the adsorbent while bringing them into contact with each other to desorb the sulfur from the adsorbent without deteriorating the sulfur, and a second heating process for heating the regeneration gas and the adsorbent after the first heating process while bringing them into contact with each other at a temperature higher than that of the first heating process.

Description

  The present invention relates to a method for regenerating an adsorbent.

Carbon such as n-butene, isobutene, n-butane, isobutane, etc., with the development of technology such as thermal decomposition of naphtha and fluid catalytic cracking of heavy oil such as heavy gas oil, vacuum gas oil, and atmospheric residue A C4 fraction containing a component having a number of 4 (hereinafter referred to as “C4 fraction”) can be easily produced and is available on the market. Since the diene component contained in the C4 fraction can be removed by hydrogenation, a method for effectively using the C4 olefin component obtained by removing the diene component from the C4 fraction has been studied.
Against this background, in recent years, C4 olefin components obtained by pyrolyzing naphtha or by fluid catalytic cracking of heavy oil such as heavy gas oil, vacuum gas oil and atmospheric distillation residue are polymerized. Various methods for producing gasoline base materials have been provided.

In general, polymerization catalysts and reaction catalysts are poisoned by trace impurities (on the order of several mass ppm) such as diene, sulfur, moisture, oxygen-containing compounds contained in raw materials such as C4 fractions, and the catalytic activity of these catalysts is Decrease significantly.
Therefore, various removal apparatuses are installed to remove these trace impurities. And when the density | concentration of a trace amount impurity is several mass ppm-several hundred mass ppm, the adsorption removal method using adsorption agent is employ | adopted (for example, refer patent document 1).
In the adsorption removal method described in Patent Document 1, an adsorbent is provided in the removal device in order to remove the sulfur content in the hydrocarbon oil as a raw material. If the raw material is continuously introduced into the removing device, the adsorption capacity of the adsorbent approaches saturation, so that the adsorbent is regenerated at a predetermined timing before saturation. As a method for regenerating the adsorbent, a method in which a high-temperature inert gas or hydrogen gas is brought into contact with the adsorbent is used.
Usually, the removal is continuously performed by sequentially switching two or more removal devices so that the sulfur content can be removed during regeneration of the adsorbent. That is, while the adsorbent regeneration of the removal apparatus after use is performed, the removal process is performed by switching to another removal apparatus having a new adsorbent or a regenerated adsorbent.

JP 2003-277768 A

  However, as in Patent Document 1, a removal method that sequentially switches the removal device to be used before the adsorption capability of the adsorbent is saturated is adopted, and the adsorbent is regenerated with a high-temperature gas. A decrease in the catalytic activity of the reactor arranged in the process was observed. This decrease in catalyst activity was caused by poisoning of the catalyst by sulfur. In other words, in the conventional adsorbent regeneration method, the adsorption capacity is not sufficiently regenerated, and some form of sulfur remains in the adsorbent. I found out that it was leaked.

  An object of the present invention is to provide a method for regenerating an adsorbent capable of preventing the sulfur content from remaining in the adsorbent.

The present invention
An adsorbent regeneration method for regenerating an adsorbent for adsorbing sulfur in a raw material,
A first heating step in which the regeneration gas and the adsorbent are heated in contact with each other and desorbed from the adsorbent without altering the sulfur content;
After the first heating step, a second heating step of heating the regeneration gas and the adsorbent at a temperature higher than the temperature of the first heating step is provided.

In the adsorbent regeneration method of the present invention,
The raw material is obtained by pyrolyzing a naphtha fraction, which is an atmospheric distillation fraction of crude oil, or by subjecting a heavy gas oil, an atmospheric distillation residue, or an atmospheric distillation residue, which is an atmospheric distillation fraction, to vacuum distillation. The C4 fraction obtained by catalytic cracking of the vacuum gas oil fraction obtained in this manner is preferred.

Furthermore, in the regeneration method of the adsorbent of the present invention,
The sulfur content includes mercaptans,
The adsorbent includes X-type zeolite containing sodium,
The heating temperature in the first heating step is preferably 90 ° C. or higher and 140 ° C. or lower.

  According to the present invention, it is possible to prevent the sulfur content from remaining in the adsorbent.

1 is a schematic view of a gasoline base material production apparatus having a sulfur content removal apparatus in which an adsorbent regeneration method according to an embodiment of the present invention is performed. Schematic which shows the temperature transition of the heating process at the time of adsorbent reproduction | regeneration which concerns on the said embodiment. GC / SCD chromatogram of raw material C4 fraction. GC / SCD chromatogram of C4 fraction after room temperature treatment. The GC / SCD chromatogram figure of C4 fraction after a 90 degreeC process. The GC / SCD chromatogram figure of C4 fraction after a 120 degreeC process. The GC / SCD chromatogram figure of C4 fraction after a 150 degreeC process. The GC / SCD chromatogram figure of C4 fraction after a 220 degreeC process. Schematic which shows the temperature transition of the heating process in the conventional adsorbent reproduction | regeneration method.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In the present embodiment, the adsorbent regeneration method according to the present invention is applied to an adsorbent provided in a sulfur content removing device that constitutes a part of a low sulfur gasoline base material manufacturing apparatus.
<Low sulfur gasoline base material manufacturing equipment>
FIG. 1 is a schematic view of a low sulfur gasoline base material manufacturing apparatus according to the present invention.
As shown in FIG. 1, the low-sulfur gasoline base material manufacturing apparatus 100 thermally decomposes a naphtha fraction that is an atmospheric distillation fraction of crude oil or heavy gas oil or atmospheric distillation residue that is an atmospheric distillation fraction of crude oil. Alternatively, a sulfur removal device 200 for removing sulfur contained in a C4 fraction produced by catalytic cracking of a vacuum gas oil fraction obtained by further subjecting an atmospheric distillation residue to distillation under reduced pressure, and a sulfur removal A diene component removing device 300 for removing a diene component contained in a C4 fraction from which sulfur content has been removed in the apparatus 200 and a C4 fraction from which the diene component has been removed in the diene component removing device 300 are polymerized. And a polymerization apparatus 400.

[Sulfur content removal equipment]
The sulfur content removing device 200 is used in a process (sulfur content adsorption process) for bringing the adsorbent provided therein and the C4 fraction into contact with each other to adsorb the sulfur content in the C4 fraction to the adsorbent. . In addition, the sulfur content removal apparatus 200 can also adsorb impurities other than the sulfur content.
The sulfur removal device 200 is a pyrolysis device (not shown) that thermally decomposes a naphtha fraction that is a fraction obtained by atmospheric distillation of crude oil, a heavy light oil that is an atmospheric distillation fraction of crude oil, or an atmospheric distillation residue. It is connected to a fluid catalytic cracking apparatus (not shown) for carrying out catalytic cracking of a vacuum gas oil fraction obtained by further vacuum distillation of oil or atmospheric distillation residue. The C4 fraction produced by thermal cracking or catalytic cracking is supplied to the sulfur content removing device 200.
Although the shape of the sulfur content removing device 200 used in the present embodiment is not particularly limited, a tower-shaped one is preferably used. The method for bringing the adsorbent into contact with the C4 fraction is not particularly limited, and any of a fixed bed type, a moving bed type, and a fluidized bed type can be adopted, but a fixed bed type is preferred.
As shown in FIG. 1, the sulfur content removing device 200 is composed of two components, a sulfur content removing device 200A and a sulfur content removing device 200B, which are connected in parallel. A method of switching to another refurbished or new apparatus equipped with an adsorbent while regenerating the adsorbent of the apparatus with reduced sulfur content by connecting two sulfur content removing devices in parallel Can be adopted. Therefore, it is possible to continuously operate the low-sulfur gasoline base material production apparatus without stopping, and to minimize the sulfur content removal apparatus. Three or more sulfur content removing devices 200 may be connected in parallel.

(Adsorbent)
The adsorbent adsorbs impurities described later contained in the C4 fraction. As the adsorbent, X-type zeolite containing sodium is used, and preferably, a hybrid type adsorbent in which the X-type zeolite and activated alumina are mixed is used. X-type zeolite is excellent in initial adsorption capacity. Although the hybrid type adsorbent is inferior to the X-type zeolite alone in terms of initial adsorption performance, the adsorption when the C4 fraction and the adsorbent are in contact with each other is subjected to heat treatment (for example, heat regeneration treatment of the adsorbent). In terms of performance, it is superior to the X-type zeolite alone. That is, the adsorption capacity of the hybrid adsorbent is stable even when it is repeatedly used while being regenerated. Therefore, it becomes easy to set the amount of adsorbent filled in the sulfur content removing device 200. In this embodiment, a hybrid type adsorbent is used.
The hybrid adsorbent adsorbs sulfur, moisture, nitrogen and oxygen-containing compounds. In addition, although a dehydration tower may be installed in the previous process of the sulfur content removal apparatus 200 to remove moisture, moisture that cannot be removed may be adsorbed by a hybrid adsorbent. In addition, a water-washing tower may be installed in a pre-process of the sulfur content removal apparatus 200 (a pre-process of the dehydration tower when a dehydration tower is installed) to remove nitrogen and oxygen-containing compounds with water. Nitrogen components that cannot be removed and oxygen-containing compounds may be adsorbed by a hybrid adsorbent.

(Components contained in C4 fraction)
In the C4 fraction supplied to the sulfur content removing device 200, in addition to hydrocarbon components having 4 carbon atoms such as n-butene, isobutene, n-butane, isobutane and butadiene, sulfur content, moisture, Contains oxygenates. Of these, the catalyst in the polymerization apparatus 400 is poisoned by diene components such as butadiene, sulfur, moisture, oxygen-containing compounds, and the like, and the polymerization reaction activity decreases. That is, a diene component, a sulfur content, moisture, an oxygen-containing compound, and the like are impurities (catalyst poison) and need to be removed from the C4 fraction.

  Mercaptan is mainly contained as the sulfur content in the C4 fraction. Mercaptan is a sulfur compound RSH (R is a hydrocarbon group such as an alkyl group or an aryl group) having a mercapto group (—SH), and is also called a thiol or a thioalcohol. Examples of mercaptans contained in the C4 fraction include methyl mercaptan and ethyl mercaptan.

[Sulfur content removal process]
Next, a process of removing mercaptan as a sulfur content from the C4 fraction with the sulfur content removing device 200 will be described. Here, a case where the C4 fraction is circulated through one sulfur content removing device 200A and then the adsorbent of the sulfur content removing device 200A is regenerated will be described as an example.
The C4 fraction is sent to the sulfur content removing device 200A by the switching unit 210A in front of the sulfur content removing device 200.
In the sulfur removing device 200A, the adsorbent and the C4 fraction come into contact with each other, and impurities such as sulfur are adsorbed on the adsorbent. The C4 fraction from which impurities have been adsorbed and removed passes through the switching unit 210B and is supplied to the diene component removal apparatus 300.

The temperature at which the adsorbent is brought into contact with the C4 fraction is 0 ° C. or higher and 70 ° C. or lower, preferably 15 ° C. or higher and 40 ° C. or lower.
Moreover, as a pressure at the time of making an adsorbent and a C4 fraction contact, it is 0.02 MPa or more and 2.0 MPa or less, Preferably, it is 0.5 MPa or more and 1.5 MPa or less.

The concentration of the sulfur content in the C4 fraction after the sulfur content removal treatment is preferably less than 10 ppm by mass. This is because, in the sulfur removal step, if the sulfur concentration in the C4 fraction is less than 10 mass ppm, the sulfur concentration contained in the gasoline base material is finally less than 10 mass ppm.
Moreover, it is more preferable if the concentration of the sulfur content is less than 1 ppm by mass. In the sulfur removal step, if the sulfur concentration in the C4 fraction is less than 1 mass ppm, the sulfur concentration contained in the gasoline base material is also less than 1 mass ppm. Therefore, a high value-added gasoline base material having a lower sulfur content can be obtained.

[Adsorbent regeneration process]
Thereafter, the adsorption of impurities is continued in the sulfur content adsorption process, and the supply of the C4 fraction is switched to the sulfur content removal device 200B at the stage where the adsorption capacity has reached saturation or before the saturation is reached, to the sulfur content removal device 200A. The supply of the C4 fraction is stopped. Thereafter, the C4 fraction remaining in the sulfur removing device 200A is extracted. Then, a high-temperature regeneration gas is introduced into the sulfur content removing device 200A, the adsorbent and the regeneration gas are brought into contact with each other, and impurities such as sulfur content are desorbed from the adsorbent. The method for introducing the regeneration gas in the sulfur content removal apparatus 200A is not particularly limited. For example, when the sulfur content removal apparatus 200A has a tower shape, it is preferable to introduce the regeneration gas from the upper part of the tower under predetermined conditions.
As the regeneration gas, inert gas, by-product fuel gas, natural gas, hydrogen gas, and the like can be used. In particular, by-product natural gas is preferable from the viewpoint of being easily available from refineries and factories and from an economical viewpoint. .

In the present invention, as shown in FIG. 2, a first heating step and a second heating step are provided as heating steps for regenerating the adsorbent. In each heating step, the regeneration gas maintained at a predetermined temperature is circulated through the sulfur content removing device 200 to heat the adsorbent.
In the first heating process as the first stage, the heated regeneration gas is brought into contact with the adsorbent to heat the adsorbent, and in the second heating process as the second stage, the regeneration gas temperature is set higher than that in the first heating process. The temperature is raised to and maintained at a high temperature, and the adsorbent is heated at that temperature. In the first heating step, the sulfur content adsorbed on the adsorbent is desorbed without alteration, and in the second heating step, other impurities (nitrogen content and oxygen-containing compound) are desorbed. Here, desorbing without altering the sulfur content means desorbing the sulfur content adsorbed on the adsorbent from the adsorbent without changing to another substance.
The heating temperature in the first heating step is preferably 90 ° C. or higher and 140 ° C. or lower. By setting the temperature to 90 ° C. or higher, mercaptans contained in the C4 fraction can be easily detached from the adsorbent. Moreover, by setting it as 140 degrees C or less, as mentioned later, other sulfur content (Dimethyl sulfide, tert- butyl mercaptan, etc .. These are named generically and it is also called a modified sulfur content) is prevented from producing | generating. be able to.
In the present embodiment, the heating temperature in the first heating step is 120 ° C. In the present embodiment, the temperature of the second heating step is 270 ° C. in order to sufficiently desorb impurities other than the sulfur content from the adsorbent.
Since the heating time of the first heating step and the second heating step depends on the device size of the sulfur content removing device 200, it is preferable to set after confirming in advance the time during which no impurities remain in the adsorbent.
It is preferable that the regeneration gas flow rate in the first heating process and the second heating process is appropriately used in an amount equal to or greater than the minimum necessary regeneration gas amount depending on the amount of the adsorbed substance such as sulfur and the amount of the adsorbent.

While the adsorbent in the sulfur content removing device 200A is being regenerated, the switching unit 210A and the switching unit 210B are switched, and the sulfur content removing device 200B provided with the regenerated or new adsorbent as described above has a C4 retention. The minute is supplied and the impurity is adsorbed.
Thereafter, when the adsorption capacity of the adsorbent of the sulfur content removal device 200B reaches saturation, the supply of the C4 fraction is switched to the sulfur content removal device 200A that has finished the regeneration process, and the C4 fraction is regenerated with respect to the regenerated adsorbent. Contact. In the present embodiment, removal and regeneration are performed while the sulfur content removing devices 200A and 200B are switched in a 24-hour cycle.

(Check for leaks)
In addition, when confirming the leak of the sulfur content to the C4 fraction adsorbed by the sulfur content removal apparatus 200A, the C4 fraction is collected before the switching unit 210B on the downstream side of the sulfur content removal apparatus 200, Measure the concentration. The measurement is carried out by the sulfur content test method (trace coulometric titration method) of JIS K2240.
The adsorbent regeneration method of this embodiment was performed, and leakage of sulfur to the C4 fraction was confirmed. When the regeneration method of the present embodiment was performed, the sulfur content was not detected even after 24 hours from the start of the circulation of the C4 fraction, and no leak occurred. For the reasons described later, it was confirmed that when the regeneration method of the present embodiment is performed, the sulfur content is prevented from remaining in the adsorbent.

  The reason why the adsorbent regeneration method according to the present invention can prevent the sulfur content from remaining in the adsorbent and the sulfur content from leaking to the raw material by taking the case of adopting the conventional adsorbent regeneration method as an example below. Will be described.

(Conventional adsorbent regeneration method)
For comparison with the playback method of this embodiment, a conventional playback method will be described.
As a conventional regeneration method, a one-step heating process as described in Patent Document 1 is performed. As an example of the heating step in the conventional regeneration method, a schematic diagram is shown in FIG.
Here, the regeneration gas temperature of the adsorbent is increased to 270 ° C., which is the same as the temperature in the second heating step of the present embodiment, so that not only sulfur but also impurities such as nitrogen can be desorbed from the adsorbent. Keep warm.
Other than the above, in the same manner as the adsorbent regeneration method of the present embodiment described above, the flow of the C4 fraction is switched to the sulfur content removal device 200A that has completed the regeneration process, and the C4 fraction is then added to the regenerated adsorbent. Make contact. Further, leakage of sulfur content is performed in the same manner as described above.

(Confirmation of leaks when the conventional adsorbent regeneration method is used)
A conventional adsorbent regeneration method was performed, and leakage of sulfur to the C4 fraction was confirmed. In the case of performing the conventional regeneration method, the sulfur content started to be detected ten hours later after the circulation of the C4 fraction was started, and the sulfur content concentration gradually increased. That is, it was found that a leak occurred.

(Analysis of leaked sulfur)
The composition of the leaked sulfur was analyzed by gas chromatogram method using a chemiluminescence sulfur detector (SCD). , Referred to as TBM). Since DMS and TBM are contained in natural gas as an odorant, when natural gas is used as an adsorbent regeneration gas, DMS and TBM may be detected, but are contained in natural gas. The amount of leaked DMS and TBM was much larger than the amount of DMS and TBM. Therefore, it was speculated that DMS and TBM were generated from mercaptans as sulfur contained in the C4 fraction in some form.

(Confirmation of DMS and TBM generation)
In order to confirm that DMS and TBM are produced from mercaptan as the sulfur content in the sulfur content removing device, a simple immersion experiment was conducted. In a cylindrical reaction vessel filled with an adsorbent, the C4 fraction was placed and sealed, and the C4 fraction was brought into contact with the adsorbent while holding the reaction vessel under various temperature conditions for 12 hours. The temperature conditions were room temperature, 90 ° C., 120 ° C., 150 ° C. and 220 ° C. The GC / SCD chromatograms of FIGS. 4 to 8 show the state of production of modified sulfur components such as DMS and TBM. For comparison, a GC / SCD chromatogram of the raw material C4 fraction is shown in FIG. The raw C4 fraction, a sulfur mass conversion, 2.7 wt% of the carbonyl sulfide (COS), 90.0% by weight of methyl mercaptan _(CH 3 -SH), 7.3 wt% of ethyl mercaptan _{(C 2} H ₅ -SH) were included.
As a result, formation of DMS (CH ₃ —SH—CH ₃ ) and TBM (t—C ₄ H ₉ —SH) was not confirmed at room temperature and 90 ° C., but DMS and TBM were not observed at 150 ° C. and 220 ° C. Generation was confirmed.
As described above, when the C4 fraction containing mercaptan as the sulfur content and the adsorbent were kept in contact at a high temperature such as 220 ° C., DMS and TBM were generated. That is, in the conventional adsorbent regeneration method, since the regeneration gas temperature of the adsorbent is 270 ° C., DMS and TBM are generated, and these leak in the C4 fraction.

(DMS and TBM generation mechanism)
From the above examination results, the mechanism by which DMS and TBM are generated is estimated as follows.
The following formula (1) shows normal physical adsorption of mercaptans. In the formula (1), * represents a physical adsorption point of the adsorbent. Formula (1) shows that when the temperature is 140 ° C. or lower, the rightward reaction proceeds predominately, and mercaptan is adsorbed by the adsorbent, but when the temperature is 150 ° C. or higher, the leftward reaction proceeds predominately. . That is, when the temperature rises, the desorption of mercaptan from the physical adsorption point is promoted.

  The following formula (2) indicates that the mercaptan adsorbed on the adsorbent is chemically adsorbed with sodium (hereinafter referred to as Na) contained in the adsorbent. Equation (2) is considered to proceed predominantly to the right at high temperatures (150 ° C. or higher).

The following formula (3) indicates that DMS and hydrogen sulfide (hereinafter referred to as H ₂ S) are produced from the reaction product of mercaptan and Na produced in formula (2). Formula (3) proceeds at a high temperature (150 ° C. or higher) during regeneration of the adsorbent.

The following formulas (4) and (5) indicate that DMS and H ₂ S are desorbed from the physical adsorption points, respectively. Formulas (4) and (5) also proceed at a high temperature (220 ° C. or higher) during regeneration of the adsorbent, but the total amount of DMS and H ₂ S adsorbed on the physical adsorption point is not desorbed, but partly adsorbed And remain.
The remaining DMS is desorbed from the physical adsorption point by the mercaptan in the C4 fraction when the C4 fraction is newly distributed. The desorbed DMS is adsorbed at the physical adsorption point of the adsorbent provided downstream with respect to the flow direction of the C4 fraction in the sulfur content removal apparatus 200. In this way, DMS moves in the downstream direction while repeating desorption and adsorption, and leaks from the sulfur content removal device after a predetermined time has elapsed.

The following formula (6) shows that H ₂ S remaining after adsorbing at the physical adsorption point during the regeneration of the adsorbent reacts with isobutene in the C4 fraction to generate TBM. Similarly to DMS, the TBM is also deprived of its physical adsorption point by mercaptan, moves in the downstream direction while repeating desorption and adsorption, and leaks from the sulfur content removal device after a predetermined time.

Based on the reaction mechanism of the above formulas (1) to (6), if mercaptan is desorbed from the adsorbent in a temperature range where the mercaptan adsorbed on the adsorbent is not chemically adsorbed with Na contained in the adsorbent, It can be said that the generation of H ₂ S that causes the generation of DMS and TBM is suppressed, and the residual sulfur content in the adsorbent and the leakage of the modified sulfur content can be prevented. However, in order to desorb impurities (nitrogen oxides, etc.) other than sulfur contained in the C4 fraction from the physical adsorption point, the temperature at which the desorption of mercaptan of formula (1) proceeds preferentially is insufficient. It is. For this, it can be said that a heating process for preferentially proceeding with desorption of impurities other than the sulfur content may be provided separately.
From such a study, adsorbent regeneration is performed in two stages, that is, (i) a first heating step in which desorption of mercaptans proceeds in a temperature range in which the mercaptan adsorbed on the adsorbent does not chemically adsorb with Na contained in the adsorbent. And (ii) the second heating step in which desorption of other impurities proceeds predominantly, it is possible to prevent alteration of sulfur content adsorbed on the adsorbent (degradation from mercaptan to DMS or TBM), and altered sulfur. It has been found that it is possible to prevent the remaining of the water in the adsorbent and to prevent the leakage of the modified sulfur to the C4 fraction.

Next, other devices constituting the low-sulfur gasoline base material manufacturing apparatus 100 will also be described.
[Diene component removal equipment]
The diene component removal apparatus 300 is connected to the sulfur content removal apparatus 200 on the upstream side. The C4 fraction sent out from the sulfur removing device 200 is supplied to the diene component removing device 300.

The diene component removal apparatus 300 is an extraction method in which the diene component is extracted and removed from the C4 fraction with a solvent, a hydrogenation removal method in which the diene component is removed by hydrogenation (sometimes referred to as a hydrogenation removal method), and other known methods. The method can be carried out. In this embodiment, a hydrogenation removal method is used.
The extraction method is suitable when the diene component is recovered from the raw material containing the diene component at a high concentration and used as a raw material for synthetic rubber, for example. In the case of extracting and recovering from a diene raw material having a diene concentration of about 1% by mass or less, the equipment costs for the extraction tower, solvent recovery equipment, etc. are high, which is not economical. Further, the cost is high in terms of energy. Therefore, the hydrogenation removal method is suitable.
In this embodiment, since the hydrogenation removal method is used, hydrogen is supplied to the diene component removal apparatus 300 from a different route from the C4 fraction.
In the hydrogenation removal method, usually, palladium / alumina is used as a catalyst, the reaction temperature is 30 ° C. to 150 ° C., the pressure is 0.1 MPa to 3 MPa, SV (Space
Velocity: The space velocity) as 0.1 hr ^-1 or more 10 hr ^-1 or less, may be performed by a known fixed-bed reactor and the like. The processing conditions, the reaction temperature 50 ° C. or higher 100 ° C. or less, more 0.3MPa pressure 1.5MPa or less, particularly preferably at ^{1hr -1} or ^{5 hr -1} or less SV.

[Polymerization equipment]
The polymerization apparatus 400 is connected to the diene component removal apparatus 300 on the upstream side. The C4 fraction sent out from the diene component removing device 300 is supplied to the polymerization device 400.
As described above, the polymerization apparatus 400 is an apparatus for polymerizing (dimerizing) the C4 fraction. The polymerization reaction can be carried out using a known method. For example, silica alumina, zeolite, aluminum chloride or the like is used as a catalyst, the polymerization conditions are a reaction temperature of 20 ° C. to 180 ° C., a pressure of 1 MPa to 10 MPa, and SV of 0.01 hr ^{−1 to} 50 hr ^−1. Just do it. The processing conditions, the reaction temperature 50 ° C. or higher 0.99 ° C. or less, the reaction pressure 2MPa least 6MPa less, and particularly preferably 0.1 hr ^-1 or more 10 hr ^-1 or less SV.

A fractionator (not shown) is connected to the downstream side of the polymerization apparatus 400. This fractionation apparatus is a gasoline base material mainly composed of isooctene, and a fraction having a carbon number smaller than the carbon number of components contained in the gasoline base material, from a polymerization reaction product polymerized by the polymerization apparatus 400. (Unreacted fraction) and a polymerization by-product having more carbon atoms than components contained in the gasoline base material. That is, a gasoline base material mainly composed of isooctene having a high octane number can be recovered by fractional distillation.
The unreacted fraction is supplied to, for example, an ethylene production apparatus and used as an ethylene production raw material. Further, the polymerization by-product is supplied to, for example, a fluid catalytic cracker, and is separately used as a cracked gasoline base material or a petrochemical raw material.

<Method for producing low-sulfur gasoline base material>
First, the C4 fraction produced by the thermal cracking of the naphtha fraction, the heavy gas oil, the atmospheric distillation residual oil, or the catalytic cracking of the vacuum gas oil is supplied to the sulfur removal device 200.

[Sulfur content removal process]
The sulfur content removing apparatus 200 removes sulfur content and other impurities in the C4 fraction by the above-described method.

[Diene component removal step]
Next, the diene component removal apparatus 300 removes the diene component contained in the C4 fraction sent out from the sulfur content removal apparatus 200. As a removal method, the hydrogenation removal method described above is used.
Here, the concentration of the diene component in the C4 fraction after the hydrogenation removal treatment is preferably less than 0.1% by mass.
In addition, the composition analysis of C4 fraction is analyzed by the composition analysis method (gas chromatograph method) of JIS K2240.

[Polymerization process]
Next, the polymerization apparatus 400 causes the polymerization reaction (dimerization) of the C4 fraction supplied from the diene component removal apparatus 300. The polymerization reaction can be performed under the conditions described above.
After the polymerization reaction, a fractionation device (not shown) includes a gasoline base material mainly composed of isooctene and a fraction (unreacted fraction) having a carbon number smaller than the carbon number of components contained in the gasoline base material. ) And a polymerization by-product having more carbon atoms than the components contained in the gasoline base material.

<Effects of Embodiment>
According to the above-described embodiment, the following operational effects can be achieved.
In adsorbent regeneration, mercaptans (sulfur content) adsorbed on the adsorbent are desorbed in the first heating step, and other impurities are desorbed in the second heating step. It is possible to prevent residual impurities.
And before it reaches the temperature at which H ₂ S that causes DMS and TBM formation is generated, mercaptan is desorbed from the adsorbent in the first heating step, so that DMS leaking into the C4 fraction Generation of TBM can be prevented. As a result, leakage of DMS or TBM as a sulfur content into the C4 fraction can be prevented.

  Moreover, since sulfur content leakage is prevented by the sulfur content removing device 200, it is possible to prevent a decrease in the catalytic activity of the polymerization reaction caused by the sulfur content as the catalyst poison.

<Modification>
The aspect described above shows one aspect of the present invention, and the present invention is not limited to the above-described embodiment, and is within the scope of achieving the object and effect of the present invention. Needless to say, modifications and improvements are included in the content of the present invention. Further, the specific structure, shape, and the like in carrying out the present invention are not problematic as other structures, shapes, and the like as long as the objects and effects of the present invention can be achieved.

  In the embodiment, the method for regenerating the adsorbent according to the present invention has been described with reference to an example in which the sulfur content removing device 200 is installed on the upstream side of the polymerization apparatus that generates the gasoline base material. However, the present invention is not limited to this. For example, the adsorbent regeneration method according to the present invention can be applied even when a sulfur content removal device 200 is installed as one of the impurity removal devices in a propylene conversion facility. The catalyst charged in the propylene synthesizer of the propylene conversion facility is also poisoned by impurities such as sulfur. Therefore, if the regeneration method of the adsorbent according to the present invention is applied, it is possible to prevent sulfur from leaking to the raw material for propylene synthesis and to prevent poisoning of the catalyst for propylene synthesis.

  Further, the switching cycle of the sulfur content removing device 200 is not limited to 24 hours as described in the above embodiment. Changes are appropriately made depending on the amount of adsorption treatment of C4 fraction, apparatus size, number of apparatuses, adsorbent filling amount, and the like.

  In addition, the first heating process in which the sulfur content adsorbed on the adsorbent is desorbed without alteration may be divided into a plurality of stages.

  EXAMPLES Hereinafter, although an Example and a reference example are given and this invention is demonstrated more concretely, this invention is not limited to the content of an Example etc. at all.

Example 1
Impurity adsorption processing and adsorbent regeneration processing in the C4 fraction were performed in the sulfur content removal apparatus 200 described in the above embodiment, and leakage of sulfur content from the sulfur content removal apparatus 200 was examined.
In each of the sulfur content removing devices 200A and 200B,
A hybrid adsorbent (manufactured by UOP, model number: AZ-300) was filled.
The cracked product obtained by cracking the vacuum gas oil with a fluid catalytic cracking device was separated by distillation, and the C4 fraction contained therein was supplied to the sulfur removing device 200A. The conditions for adsorbing impurities such as sulfur were 25 ° C. and 1.2 MPa. The sulfur concentration in the supplied C4 fraction was 35 ppm by mass. The sulfur concentration in the C4 fraction was measured by the sulfur content test method (trace coulometric titration method) described in JIS K2240.

24 hours after supplying the C4 fraction to the sulfur content removing device 200A, the switching units 210A and 210B were switched so that the C4 fraction was supplied to the sulfur content removing device 200B. Thereafter, the liquid remaining in the sulfur content removing device 200A was removed, and the adsorbent was regenerated.
Natural gas was used as the regeneration gas. First, 90 ° C. regeneration gas was introduced, and the regeneration gas temperature was raised to 120 ° C. In the first heating step, a regeneration gas at 120 ° C. was introduced into the sulfur content removing device 200A for 70 minutes to heat the adsorbent. Thereafter, the regeneration gas temperature was raised to 270 ° C., and in the second heating step, the regeneration gas at 270 ° C. was introduced into the sulfur content removal apparatus 200A for 420 minutes to heat the adsorbent. The gas flow rate in the first heating step and the second heating step was 132 kNm ³ / D. In Example 1, the time from the start of introducing the regeneration gas at 90 ° C. until the regeneration of the adsorbent was completed was 560 minutes.

  Then, 24 hours after the start of the adsorption treatment in the sulfur content removing device 200B, the supply of the C4 fraction was switched to the sulfur content removing device 200A. And C4 fraction was extract | collected before the switching part 210B of the downstream of the sulfur content removal apparatus 200A, the sulfur content density | concentration was measured, and the time-dependent change of the leak amount of a sulfur content was confirmed.

(Comparative Example 1)
In Comparative Example 1, except that the regeneration conditions during regeneration of the adsorbent in Example 1 were changed, the impurity adsorption treatment and the adsorbent regeneration treatment in the C4 fraction were performed under the same conditions, and the sulfur from the sulfur removing device 200 Checked for leaks in minutes. In Comparative Example 1, without introducing a two-step heating process as in Example 1, the introduction of a regeneration gas at 90 ° C. was started and the temperature was raised to 270 ° C. Thereafter, the regeneration gas at 270 ° C. was introduced into the sulfur content removing device 200A for 420 minutes to heat the adsorbent. In Comparative Example 1, the time from the start of introducing the regeneration gas at 90 ° C. to the end of the regeneration of the adsorbent was 480 minutes.

In Example 1, the sulfur content was not detected until the next switching timing (after 24 hours) from the sulfur content removing device 200A to the sulfur content removing device 200B.
On the other hand, in Comparative Example 1, the sulfur content was detected about 14 hours after switching to the sulfur content removing device 200A. The sulfur content detected here was DMS and TBM.
Thus, as in Example 1, a two-step heating process is provided to regenerate the adsorbent, first desorbing the sulfur (mercaptan) from the adsorbent, and then raising the temperature to adsorb other impurities. It was found that leakage of the sulfur content within the switching time (24 hours) of the sulfur content removal devices 200A and 200B can be prevented by desorption from the agent.
On the other hand, when the sulfur content and other impurities are collectively desorbed from the adsorbent in a single heating step (270 ° C.) as in Comparative Example 1, the switching time of the sulfur content removal devices 200A and 200B ( It was found that the sulfur content leaks within 24 hours).

  The method for regenerating an adsorbent according to the present invention can be used for regenerating an adsorbent that adsorbs a sulfur content contained in a raw material.

100 Low Sulfur Gasoline Base Material Production Equipment 200, 200A, 200B Sulfur Content Removal Equipment 210A, 210B Switching Unit 300 Diene Component Removal Equipment 400 Polymerization Equipment

Claims (3)

An adsorbent regeneration method for regenerating an adsorbent for adsorbing sulfur in a raw material,
A first heating step in which the regeneration gas and the adsorbent are heated in contact with each other and desorbed from the adsorbent without altering the sulfur content;
A second heating step of heating the regeneration gas and the adsorbent in contact with each other at a temperature higher than the temperature of the first heating step, after the first heating step. Method. In the regeneration method of the adsorbent according to claim 1,
The raw material is obtained by pyrolyzing a naphtha fraction, which is an atmospheric distillation fraction of crude oil, or by subjecting a heavy gas oil, an atmospheric distillation residue, or an atmospheric distillation residue, which is an atmospheric distillation fraction, to vacuum distillation. A method for regenerating an adsorbent, which is a C4 fraction obtained by catalytic cracking of a vacuum gas oil fraction obtained in this way. In the regeneration method of the adsorbent according to claim 1 or 2,
The sulfur content includes mercaptans,
The adsorbent includes X-type zeolite containing sodium,
The heating temperature of said 1st heating process is 90 degreeC or more and 140 degrees C or less temperature. The regeneration method of the adsorption agent characterized by the above-mentioned.

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